An NK cell in action

Credit: Bjorn Onfelt/Dan Davis

In vitro experiments suggest a patient’s own natural killer (NK) cells can be expanded and modified to fight acute lymphoblastic leukemia (ALL).

Researchers successfully expanded CD56+ cells isolated from the bone marrow and peripheral blood of ALL patients.

And these cells exhibited cytotoxicity against the patients’ own ALL cells. The effect was enhanced by the addition of IL-15 and a monoclonal antibody (mAb) targeting BAFF-R.

Hisham Abdel-Azim, MD, of Children’s Hospital Los Angeles, and his colleagues reported these results in Leukemia.

The researchers first used flow cytometry to detect CD56+ cells in bone marrow and peripheral blood samples from ALL patients. The team discovered these cells were detectable at diagnosis, post-induction, and relapse.

To expand the cells, the researchers cocultured them with artificial antigen-presenting K562 clone 9.mbIL-21 cells. The expanded CD56+ cells demonstrated allogeneic cytotoxicity against ALL cells, even in the absence of antibody.

The addition of a mAb targeting BAFF-R enhanced CD56+ cells’ cytotoxicity against ALL cells. The activity of these CD56+ cells was comparable to that of NK cells derived from healthy patients.

The researchers also compared CD56+CD3- cells to CD56+CD3+ cells and found the CD3- cells exhibited increased levels of activation in antibody-mediated cellular cytotoxicity reactions. The CD56+CD3+ cells were not stimulated by BAFF-R mAbs.

The team then tested the NK cells’ autologous cytotoxicity. And, as in previous experiments, the CD56+ cells from ALL samples demonstrated nonantibody-dependent cytotoxicity and enhanced cytotoxicity in the presence of BAFF-R mAbs.

Finally, the researchers decided to investigate whether the addition of IL-2 or IL-15 could further stimulate CD56+ cells’ cytotoxicity. And while they found that both cytokines did the job, IL-15 proved more successful.

“These results are very promising, with potential as a part of first-line therapy and also as a treatment for eliminating any remaining cancer cells . . . following standard chemotherapy,” Dr Abdel-Azim said. “We anticipate additional preclinical testing and then a clinical trial to evaluate the therapy in children with leukemia.”

An NK cell in action

Credit: Bjorn Onfelt/Dan Davis

In vitro experiments suggest a patient’s own natural killer (NK) cells can be expanded and modified to fight acute lymphoblastic leukemia (ALL).

Researchers successfully expanded CD56+ cells isolated from the bone marrow and peripheral blood of ALL patients.

And these cells exhibited cytotoxicity against the patients’ own ALL cells. The effect was enhanced by the addition of IL-15 and a monoclonal antibody (mAb) targeting BAFF-R.

Hisham Abdel-Azim, MD, of Children’s Hospital Los Angeles, and his colleagues reported these results in Leukemia.

The researchers first used flow cytometry to detect CD56+ cells in bone marrow and peripheral blood samples from ALL patients. The team discovered these cells were detectable at diagnosis, post-induction, and relapse.

To expand the cells, the researchers cocultured them with artificial antigen-presenting K562 clone 9.mbIL-21 cells. The expanded CD56+ cells demonstrated allogeneic cytotoxicity against ALL cells, even in the absence of antibody.

The addition of a mAb targeting BAFF-R enhanced CD56+ cells’ cytotoxicity against ALL cells. The activity of these CD56+ cells was comparable to that of NK cells derived from healthy patients.

The researchers also compared CD56+CD3- cells to CD56+CD3+ cells and found the CD3- cells exhibited increased levels of activation in antibody-mediated cellular cytotoxicity reactions. The CD56+CD3+ cells were not stimulated by BAFF-R mAbs.

The team then tested the NK cells’ autologous cytotoxicity. And, as in previous experiments, the CD56+ cells from ALL samples demonstrated nonantibody-dependent cytotoxicity and enhanced cytotoxicity in the presence of BAFF-R mAbs.

Finally, the researchers decided to investigate whether the addition of IL-2 or IL-15 could further stimulate CD56+ cells’ cytotoxicity. And while they found that both cytokines did the job, IL-15 proved more successful.

“These results are very promising, with potential as a part of first-line therapy and also as a treatment for eliminating any remaining cancer cells . . . following standard chemotherapy,” Dr Abdel-Azim said. “We anticipate additional preclinical testing and then a clinical trial to evaluate the therapy in children with leukemia.”

An NK cell in action

Credit: Bjorn Onfelt/Dan Davis

In vitro experiments suggest a patient’s own natural killer (NK) cells can be expanded and modified to fight acute lymphoblastic leukemia (ALL).

Researchers successfully expanded CD56+ cells isolated from the bone marrow and peripheral blood of ALL patients.

And these cells exhibited cytotoxicity against the patients’ own ALL cells. The effect was enhanced by the addition of IL-15 and a monoclonal antibody (mAb) targeting BAFF-R.

Hisham Abdel-Azim, MD, of Children’s Hospital Los Angeles, and his colleagues reported these results in Leukemia.

The researchers first used flow cytometry to detect CD56+ cells in bone marrow and peripheral blood samples from ALL patients. The team discovered these cells were detectable at diagnosis, post-induction, and relapse.

To expand the cells, the researchers cocultured them with artificial antigen-presenting K562 clone 9.mbIL-21 cells. The expanded CD56+ cells demonstrated allogeneic cytotoxicity against ALL cells, even in the absence of antibody.

The addition of a mAb targeting BAFF-R enhanced CD56+ cells’ cytotoxicity against ALL cells. The activity of these CD56+ cells was comparable to that of NK cells derived from healthy patients.

The researchers also compared CD56+CD3- cells to CD56+CD3+ cells and found the CD3- cells exhibited increased levels of activation in antibody-mediated cellular cytotoxicity reactions. The CD56+CD3+ cells were not stimulated by BAFF-R mAbs.

The team then tested the NK cells’ autologous cytotoxicity. And, as in previous experiments, the CD56+ cells from ALL samples demonstrated nonantibody-dependent cytotoxicity and enhanced cytotoxicity in the presence of BAFF-R mAbs.

Finally, the researchers decided to investigate whether the addition of IL-2 or IL-15 could further stimulate CD56+ cells’ cytotoxicity. And while they found that both cytokines did the job, IL-15 proved more successful.

“These results are very promising, with potential as a part of first-line therapy and also as a treatment for eliminating any remaining cancer cells . . . following standard chemotherapy,” Dr Abdel-Azim said. “We anticipate additional preclinical testing and then a clinical trial to evaluate the therapy in children with leukemia.”

Aspergillus fumigatus

Results of a retrospective study may have revealed the most accurate way to diagnose invasive aspergillosis (IA).

The fungal infection can be life-threatening, particularly for immunosuppressed patients, but it remains difficult to diagnose.

So researchers compared 3 tests used to diagnose IA and found the combination of nucleic acid sequence-based amplification (NASBA) and real-time quantitative PCR (qPCR) had a 100% positive predictive value.

The team reported this discovery in The Journal of Molecular Diagnostics.

IA is caused by the fungus Aspergillus fumigatus, which is considered by many pathologists to be the world’s most harmful mold.

“Traditional diagnostic methods, such as culture and histopathology of infected tissues, often fail to detect Aspergillus,” said study investigator Yun Xia, PhD, of the First Affiliated Hospital of Chongqing Medical University in China.

With this in mind, he and his colleagues evaluated the diagnostic performance of 2 nucleic acid amplification assays—qPCR and NASBA—and 1 antigen-detection method—galactomannan enzyme-linked immunosorbent assay (GM-ELISA)—using blood samples from 80 patients at high risk of IA.

The researchers evaluated the tests alone and in combination. Of the 80 patients, 42.5% had proven or probable IA.

Tests showed that NASBA predicted IA with the highest sensitivity—76.47%, compared to 67.65% for qPCR and 52.94% for GM-ELISA. But qPCR offered the highest specificity—89.13%, compared to 80.43% for both NASBA and GM-ELISA.

NASBA had the highest negative predictive value—82.22%, compared to 78.85% for qPCR and 69.81% for GM-ELISA. And qPCR had the highest positive predictive value—82.14%, compared to 74.29% for NASBA and 66.67% for GM-ELISA.

NASBA and qPCR each had a high Youden index as well—0.5690 and 0.5678, respectively—compared to GM-ELISA—0.3337.

And combining the tests improved their accuracy. The combination of NASBA and qPCR led to 100% specificity and a 100% positive predictive value.

Dr Xia and his colleagues also noted that NASBA offers the advantages of rapid amplification (90 minutes) and simple operation with low instrument cost, compared with qPCR and GM-ELISA.

Finally, the team stressed that although GM-ELISA is widely and routinely used for aspergillosis diagnosis, this study indicates that it is inferior to both NASBA and qPCR.

Aspergillus fumigatus

Results of a retrospective study may have revealed the most accurate way to diagnose invasive aspergillosis (IA).

The fungal infection can be life-threatening, particularly for immunosuppressed patients, but it remains difficult to diagnose.

So researchers compared 3 tests used to diagnose IA and found the combination of nucleic acid sequence-based amplification (NASBA) and real-time quantitative PCR (qPCR) had a 100% positive predictive value.

The team reported this discovery in The Journal of Molecular Diagnostics.

IA is caused by the fungus Aspergillus fumigatus, which is considered by many pathologists to be the world’s most harmful mold.

“Traditional diagnostic methods, such as culture and histopathology of infected tissues, often fail to detect Aspergillus,” said study investigator Yun Xia, PhD, of the First Affiliated Hospital of Chongqing Medical University in China.

With this in mind, he and his colleagues evaluated the diagnostic performance of 2 nucleic acid amplification assays—qPCR and NASBA—and 1 antigen-detection method—galactomannan enzyme-linked immunosorbent assay (GM-ELISA)—using blood samples from 80 patients at high risk of IA.

The researchers evaluated the tests alone and in combination. Of the 80 patients, 42.5% had proven or probable IA.

Tests showed that NASBA predicted IA with the highest sensitivity—76.47%, compared to 67.65% for qPCR and 52.94% for GM-ELISA. But qPCR offered the highest specificity—89.13%, compared to 80.43% for both NASBA and GM-ELISA.

NASBA had the highest negative predictive value—82.22%, compared to 78.85% for qPCR and 69.81% for GM-ELISA. And qPCR had the highest positive predictive value—82.14%, compared to 74.29% for NASBA and 66.67% for GM-ELISA.

NASBA and qPCR each had a high Youden index as well—0.5690 and 0.5678, respectively—compared to GM-ELISA—0.3337.

And combining the tests improved their accuracy. The combination of NASBA and qPCR led to 100% specificity and a 100% positive predictive value.

Dr Xia and his colleagues also noted that NASBA offers the advantages of rapid amplification (90 minutes) and simple operation with low instrument cost, compared with qPCR and GM-ELISA.

Finally, the team stressed that although GM-ELISA is widely and routinely used for aspergillosis diagnosis, this study indicates that it is inferior to both NASBA and qPCR.

Aspergillus fumigatus

Results of a retrospective study may have revealed the most accurate way to diagnose invasive aspergillosis (IA).

The fungal infection can be life-threatening, particularly for immunosuppressed patients, but it remains difficult to diagnose.

So researchers compared 3 tests used to diagnose IA and found the combination of nucleic acid sequence-based amplification (NASBA) and real-time quantitative PCR (qPCR) had a 100% positive predictive value.

The team reported this discovery in The Journal of Molecular Diagnostics.

IA is caused by the fungus Aspergillus fumigatus, which is considered by many pathologists to be the world’s most harmful mold.

“Traditional diagnostic methods, such as culture and histopathology of infected tissues, often fail to detect Aspergillus,” said study investigator Yun Xia, PhD, of the First Affiliated Hospital of Chongqing Medical University in China.

With this in mind, he and his colleagues evaluated the diagnostic performance of 2 nucleic acid amplification assays—qPCR and NASBA—and 1 antigen-detection method—galactomannan enzyme-linked immunosorbent assay (GM-ELISA)—using blood samples from 80 patients at high risk of IA.

The researchers evaluated the tests alone and in combination. Of the 80 patients, 42.5% had proven or probable IA.

Tests showed that NASBA predicted IA with the highest sensitivity—76.47%, compared to 67.65% for qPCR and 52.94% for GM-ELISA. But qPCR offered the highest specificity—89.13%, compared to 80.43% for both NASBA and GM-ELISA.

NASBA had the highest negative predictive value—82.22%, compared to 78.85% for qPCR and 69.81% for GM-ELISA. And qPCR had the highest positive predictive value—82.14%, compared to 74.29% for NASBA and 66.67% for GM-ELISA.

NASBA and qPCR each had a high Youden index as well—0.5690 and 0.5678, respectively—compared to GM-ELISA—0.3337.

And combining the tests improved their accuracy. The combination of NASBA and qPCR led to 100% specificity and a 100% positive predictive value.

Dr Xia and his colleagues also noted that NASBA offers the advantages of rapid amplification (90 minutes) and simple operation with low instrument cost, compared with qPCR and GM-ELISA.

Finally, the team stressed that although GM-ELISA is widely and routinely used for aspergillosis diagnosis, this study indicates that it is inferior to both NASBA and qPCR.

Plasmodium parasite infecting

an RBC; Credit: St Jude

Children’s Research Hospital

Researchers say laser optical tweezers have allowed them to study how Plasmodium falciparum interacts with red blood cells (RBCs) at the single-cell level.

The research has revealed new insights into malaria biology and may pave the way for more effective drugs or vaccines.

Julian Rayner, PhD, of the Wellcome Trust Sanger Institute in Cambridge, UK, and his colleagues described their use of laser optical tweezers in Biophysical Journal.

“Using laser tweezers to study red blood cell invasion gives us an unprecedented level of control over the whole process and will help us to understand this critical process at a level of detail that has not been possible before,” Dr Rayner said.

He and his colleagues noted that P falciparum merozoites usually leave one RBC and invade another in less than a minute. And the merozoites lose the ability to infect host cells within 2 or 3 minutes of release.

So the researchers used laser optical tweezers to study this transient event. The tweezers allow for precise control over the movements of cells by exerting extremely small forces with a highly focused laser beam.

The team used the tweezers to pick up individual merozoites that had just emerged from an RBC and deliver them to another RBC, demonstrating that the technique is suitable for studying the invasion process.

The researchers also used the tweezers to measure how strongly the merozoites adhere to RBCs. They discovered that attachment is probably mediated by multiple weak interactions, which could potentially be blocked by a combination of drugs or antibodies.

Finally, the team used the tweezers to shed light on how 3 different invasion-inhibiting drugs—heparin, cytochalasin D, and chymotrypsin—affect interactions between merozoites and RBCs.

The tweezers revealed that heparin blocks merozoite attachment to any surface, including glass slides. This suggests a receptor-independent mode of action, which contradicts the previously proposed mechanism.

Cytochalasin D, on the other hand, had no effect on attachment force, a finding that also contradicts previous thought.

And with chymotrypsin, the researchers observed 2 different effects. When merozoites adhered to chymotrypsin-treated RBCs, they did so with a reduction in the force of attachment that was similar to the effect the enzyme had on the overall efficiency of invasion.

However, merozoites that had been released more than 3 minutes previously were no longer able to adhere to chymotrypsin-treated RBCs. This suggests that chymotrypsin affects both the force of merozoite attachment and the time in which invasion can occur.

Taken together, these findings show that optical tweezers enable the study of malaria biology and drug mechanisms at the single-cell level.

“We now plan to apply this technology to dissect the process of invasion and understand what genes and proteins function at what step,” Dr Rayner said. “This will allow us to design better inhibitors or vaccines that block invasion by targeting multiple steps at the same time.”

Plasmodium parasite infecting

an RBC; Credit: St Jude

Children’s Research Hospital

Researchers say laser optical tweezers have allowed them to study how Plasmodium falciparum interacts with red blood cells (RBCs) at the single-cell level.

The research has revealed new insights into malaria biology and may pave the way for more effective drugs or vaccines.

Julian Rayner, PhD, of the Wellcome Trust Sanger Institute in Cambridge, UK, and his colleagues described their use of laser optical tweezers in Biophysical Journal.

“Using laser tweezers to study red blood cell invasion gives us an unprecedented level of control over the whole process and will help us to understand this critical process at a level of detail that has not been possible before,” Dr Rayner said.

He and his colleagues noted that P falciparum merozoites usually leave one RBC and invade another in less than a minute. And the merozoites lose the ability to infect host cells within 2 or 3 minutes of release.

So the researchers used laser optical tweezers to study this transient event. The tweezers allow for precise control over the movements of cells by exerting extremely small forces with a highly focused laser beam.

The team used the tweezers to pick up individual merozoites that had just emerged from an RBC and deliver them to another RBC, demonstrating that the technique is suitable for studying the invasion process.

The researchers also used the tweezers to measure how strongly the merozoites adhere to RBCs. They discovered that attachment is probably mediated by multiple weak interactions, which could potentially be blocked by a combination of drugs or antibodies.

Finally, the team used the tweezers to shed light on how 3 different invasion-inhibiting drugs—heparin, cytochalasin D, and chymotrypsin—affect interactions between merozoites and RBCs.

The tweezers revealed that heparin blocks merozoite attachment to any surface, including glass slides. This suggests a receptor-independent mode of action, which contradicts the previously proposed mechanism.

Cytochalasin D, on the other hand, had no effect on attachment force, a finding that also contradicts previous thought.

And with chymotrypsin, the researchers observed 2 different effects. When merozoites adhered to chymotrypsin-treated RBCs, they did so with a reduction in the force of attachment that was similar to the effect the enzyme had on the overall efficiency of invasion.

However, merozoites that had been released more than 3 minutes previously were no longer able to adhere to chymotrypsin-treated RBCs. This suggests that chymotrypsin affects both the force of merozoite attachment and the time in which invasion can occur.

Taken together, these findings show that optical tweezers enable the study of malaria biology and drug mechanisms at the single-cell level.

“We now plan to apply this technology to dissect the process of invasion and understand what genes and proteins function at what step,” Dr Rayner said. “This will allow us to design better inhibitors or vaccines that block invasion by targeting multiple steps at the same time.”

Plasmodium parasite infecting

an RBC; Credit: St Jude

Children’s Research Hospital

Researchers say laser optical tweezers have allowed them to study how Plasmodium falciparum interacts with red blood cells (RBCs) at the single-cell level.

The research has revealed new insights into malaria biology and may pave the way for more effective drugs or vaccines.

Julian Rayner, PhD, of the Wellcome Trust Sanger Institute in Cambridge, UK, and his colleagues described their use of laser optical tweezers in Biophysical Journal.

“Using laser tweezers to study red blood cell invasion gives us an unprecedented level of control over the whole process and will help us to understand this critical process at a level of detail that has not been possible before,” Dr Rayner said.

He and his colleagues noted that P falciparum merozoites usually leave one RBC and invade another in less than a minute. And the merozoites lose the ability to infect host cells within 2 or 3 minutes of release.

So the researchers used laser optical tweezers to study this transient event. The tweezers allow for precise control over the movements of cells by exerting extremely small forces with a highly focused laser beam.

The team used the tweezers to pick up individual merozoites that had just emerged from an RBC and deliver them to another RBC, demonstrating that the technique is suitable for studying the invasion process.

The researchers also used the tweezers to measure how strongly the merozoites adhere to RBCs. They discovered that attachment is probably mediated by multiple weak interactions, which could potentially be blocked by a combination of drugs or antibodies.

Finally, the team used the tweezers to shed light on how 3 different invasion-inhibiting drugs—heparin, cytochalasin D, and chymotrypsin—affect interactions between merozoites and RBCs.

The tweezers revealed that heparin blocks merozoite attachment to any surface, including glass slides. This suggests a receptor-independent mode of action, which contradicts the previously proposed mechanism.

Cytochalasin D, on the other hand, had no effect on attachment force, a finding that also contradicts previous thought.

And with chymotrypsin, the researchers observed 2 different effects. When merozoites adhered to chymotrypsin-treated RBCs, they did so with a reduction in the force of attachment that was similar to the effect the enzyme had on the overall efficiency of invasion.

However, merozoites that had been released more than 3 minutes previously were no longer able to adhere to chymotrypsin-treated RBCs. This suggests that chymotrypsin affects both the force of merozoite attachment and the time in which invasion can occur.

Taken together, these findings show that optical tweezers enable the study of malaria biology and drug mechanisms at the single-cell level.

“We now plan to apply this technology to dissect the process of invasion and understand what genes and proteins function at what step,” Dr Rayner said. “This will allow us to design better inhibitors or vaccines that block invasion by targeting multiple steps at the same time.”

Ticagrelor tablets

Credit: AstraZeneca

The US Department of Justice (DOJ) is closing its investigation of PLATO, a clinical trial of the antiplatelet agent ticagrelor (Brilinta), according to the drug’s developer, AstraZeneca.

The company also said the government is not planning any further action.

The DOJ began its investigation in October 2013, issuing a civil investigative demand requiring AstraZeneca to provide the department with documents and information related to the PLATO trial.

The trial compared ticagrelor to the antiplatelet agent clopidogrel in 18,624 patients with acute coronary syndromes (ACS), with or without ST-segment elevation.

The results suggested that ticagrelor significantly reduced the rate of myocardial infarction and death from any cause, although it did not decrease the risk of stroke. Ticagrelor did not increase the rate of overall bleeding, but it did increase the rate of bleeding not related to procedures.

These results led to ticagrelor’s approval in the US and more than 100 other countries. But members of the medical community questioned PLATO’s results, with some even suggesting the possibility of trial misconduct.

So the DOJ launched its investigation. The details of the inquiry are unclear, but AstraZeneca said it “focused on questions that have been raised previously in public about the trial.”

Many of those questions have been raised in the International Journal of Cardiology, in articles by Victor Serebruany, MD, PhD, of HeartDrug Research Laboratories in Towson, Maryland, and James DiNicolantonio, PharmD, of Wegmans Pharmacy in Ithaca, New York.

In the years since PLATO’s results were first published, Drs DiNicolantonio and Serebruany have pointed out differences between trial data published in the NEJM paper and FDA reviews of the data, noted the geographic discrepancies in results observed with ticagrelor, and raised questions about site monitoring, blinding practices, and patient deaths, among other issues.

PLATO investigators addressed these questions and allegations in an article of their own, which appeared in the International Journal of Cardiology in December 2013. The overall message was that PLATO’s results are valid.

“We have always had absolute confidence in the integrity of the PLATO trial, and we are proud of the important benefit [ticagrelor] offers to patients around the world suffering from acute coronary syndrome,” said Pascal Soriot, AstraZeneca’s Chief Executive Officer.

As for the future of ticagrelor, AstraZeneca recently announced the start of the SOCRATES trial, a study of the drug for patients with acute ischemic stroke or transient ischemic attack, and the THEMIS study in patients with type 2 diabetes and coronary atherosclerosis.

These studies form part of PARTHENON, a trial program involving more than 80,000 patients worldwide. The program also includes 2 trials that have recently completed recruitment—EUCLID, a study of patients with peripheral artery disease and PEGASUS, a study of ticagrelor for secondary prevention in patients with previous myocardial infarction.

AstraZeneca expects headline results from PEGASUS to be available in the first quarter of 2015.

Ticagrelor tablets

Credit: AstraZeneca

The US Department of Justice (DOJ) is closing its investigation of PLATO, a clinical trial of the antiplatelet agent ticagrelor (Brilinta), according to the drug’s developer, AstraZeneca.

The company also said the government is not planning any further action.

The DOJ began its investigation in October 2013, issuing a civil investigative demand requiring AstraZeneca to provide the department with documents and information related to the PLATO trial.

The trial compared ticagrelor to the antiplatelet agent clopidogrel in 18,624 patients with acute coronary syndromes (ACS), with or without ST-segment elevation.

The results suggested that ticagrelor significantly reduced the rate of myocardial infarction and death from any cause, although it did not decrease the risk of stroke. Ticagrelor did not increase the rate of overall bleeding, but it did increase the rate of bleeding not related to procedures.

These results led to ticagrelor’s approval in the US and more than 100 other countries. But members of the medical community questioned PLATO’s results, with some even suggesting the possibility of trial misconduct.

So the DOJ launched its investigation. The details of the inquiry are unclear, but AstraZeneca said it “focused on questions that have been raised previously in public about the trial.”

Many of those questions have been raised in the International Journal of Cardiology, in articles by Victor Serebruany, MD, PhD, of HeartDrug Research Laboratories in Towson, Maryland, and James DiNicolantonio, PharmD, of Wegmans Pharmacy in Ithaca, New York.

In the years since PLATO’s results were first published, Drs DiNicolantonio and Serebruany have pointed out differences between trial data published in the NEJM paper and FDA reviews of the data, noted the geographic discrepancies in results observed with ticagrelor, and raised questions about site monitoring, blinding practices, and patient deaths, among other issues.

PLATO investigators addressed these questions and allegations in an article of their own, which appeared in the International Journal of Cardiology in December 2013. The overall message was that PLATO’s results are valid.

“We have always had absolute confidence in the integrity of the PLATO trial, and we are proud of the important benefit [ticagrelor] offers to patients around the world suffering from acute coronary syndrome,” said Pascal Soriot, AstraZeneca’s Chief Executive Officer.

As for the future of ticagrelor, AstraZeneca recently announced the start of the SOCRATES trial, a study of the drug for patients with acute ischemic stroke or transient ischemic attack, and the THEMIS study in patients with type 2 diabetes and coronary atherosclerosis.

These studies form part of PARTHENON, a trial program involving more than 80,000 patients worldwide. The program also includes 2 trials that have recently completed recruitment—EUCLID, a study of patients with peripheral artery disease and PEGASUS, a study of ticagrelor for secondary prevention in patients with previous myocardial infarction.

AstraZeneca expects headline results from PEGASUS to be available in the first quarter of 2015.

Ticagrelor tablets

Credit: AstraZeneca

The US Department of Justice (DOJ) is closing its investigation of PLATO, a clinical trial of the antiplatelet agent ticagrelor (Brilinta), according to the drug’s developer, AstraZeneca.

The company also said the government is not planning any further action.

The DOJ began its investigation in October 2013, issuing a civil investigative demand requiring AstraZeneca to provide the department with documents and information related to the PLATO trial.

The trial compared ticagrelor to the antiplatelet agent clopidogrel in 18,624 patients with acute coronary syndromes (ACS), with or without ST-segment elevation.

The results suggested that ticagrelor significantly reduced the rate of myocardial infarction and death from any cause, although it did not decrease the risk of stroke. Ticagrelor did not increase the rate of overall bleeding, but it did increase the rate of bleeding not related to procedures.

These results led to ticagrelor’s approval in the US and more than 100 other countries. But members of the medical community questioned PLATO’s results, with some even suggesting the possibility of trial misconduct.

So the DOJ launched its investigation. The details of the inquiry are unclear, but AstraZeneca said it “focused on questions that have been raised previously in public about the trial.”

Many of those questions have been raised in the International Journal of Cardiology, in articles by Victor Serebruany, MD, PhD, of HeartDrug Research Laboratories in Towson, Maryland, and James DiNicolantonio, PharmD, of Wegmans Pharmacy in Ithaca, New York.

In the years since PLATO’s results were first published, Drs DiNicolantonio and Serebruany have pointed out differences between trial data published in the NEJM paper and FDA reviews of the data, noted the geographic discrepancies in results observed with ticagrelor, and raised questions about site monitoring, blinding practices, and patient deaths, among other issues.

PLATO investigators addressed these questions and allegations in an article of their own, which appeared in the International Journal of Cardiology in December 2013. The overall message was that PLATO’s results are valid.

“We have always had absolute confidence in the integrity of the PLATO trial, and we are proud of the important benefit [ticagrelor] offers to patients around the world suffering from acute coronary syndrome,” said Pascal Soriot, AstraZeneca’s Chief Executive Officer.

As for the future of ticagrelor, AstraZeneca recently announced the start of the SOCRATES trial, a study of the drug for patients with acute ischemic stroke or transient ischemic attack, and the THEMIS study in patients with type 2 diabetes and coronary atherosclerosis.

These studies form part of PARTHENON, a trial program involving more than 80,000 patients worldwide. The program also includes 2 trials that have recently completed recruitment—EUCLID, a study of patients with peripheral artery disease and PEGASUS, a study of ticagrelor for secondary prevention in patients with previous myocardial infarction.

AstraZeneca expects headline results from PEGASUS to be available in the first quarter of 2015.

The ALS ice bucket challenge has taken the social media world by storm and surprised many by how fast and far it has spread. People simply make a video of themselves dumping a bucket of ice water on their heads and then post it on a social media site and challenge others to do the same within 24 hours or make a donation to ALS research (or both).

The stunt, which began early in the summer as a challenge unrelated to amyotrophic lateral sclerosis, has resonated with many people in the dog days of summer and has been helped by many celebrities taking up the challenge. It became linked to ALS when Peter Frates, a 29-year-old man with the disease, took the challenge – albeit by nodding his head to the song "Ice Ice Baby" instead of having ice water dumped on him – and asked others to do the same.

Courtesy Wikimedia Commons/slgckgc/Creative Commons License

According to the ALS Association, as of Aug. 19, existing donors and more than 450,000 new donors have contributed $22.9 million since July 29, compared with $1.9 million during the same period last year. The ALS has a four-out-of-four stars rating on Charity Navigator, and an overall score of 90.73 out of 100. Overall, 72% of its expenses are spent on the programs and services it delivers, 11% on administration, and 17% on fundraising.

Some critics have suggested that the stunt promotes click and post activism, keeping people from doing real activism, or is "narcissism masked as altruism," but most people have embraced it as fun for a good cause.

I asked a few Clinical Neurology News editorial advisory board members to weigh in:

• Dr. Richard J. Caselli, professor of neurology at the Mayo Clinic, Scottsdale, Ariz.: "If it is raising money for ALS research, what’s not to like? Not everyone was destined to be a molecular biologist or clinical trialist, and this gives people a way to contribute that seems to be culturally in synch with the ‘social media’ community. ... The ice water is an interesting twist in that it implies that if you turn a blind eye to this cause you should punish yourself, and I suspect many people harbor feelings of at least slight guilt when they feel they are not contributing to worthwhile needs."

• Matthew Huentelman, Ph.D., associate professor of neurogenomics at the Translational Genomics Research Institute, Phoenix: "If a campaign works (and doesn’t harm) then it is hard to argue against. I think that any awareness campaign that actually gets a response from the White House has probably been a useful one. President Obama confirmed he would be donating but not doing the ice bucket thing. ... I suspect that a lot of research foundations are going to be having ‘tough’ conversations at this month’s board meetings as they compare their awareness and fundraising attempts to the simple ALS ice bucket challenge. It just demonstrates to all of us again that social media is relevant for both spreading the word and getting results. There are a few keys from this too: (1) visual "stuff" matters – short video clips is now how the world communicates; (2) challenging your friends/colleagues by name is important, too – it sort of forces a response from them; and (3) celebs are still key to pushing something viral in a truly short period of time."

(While you contemplate taking the ice bucket challenge, you might as well visit Dr. Huentelman’s social media project, MindCrowd, a site leveraging social media to recruit participants into a brain research study.)

[email protected]

The ALS ice bucket challenge has taken the social media world by storm and surprised many by how fast and far it has spread. People simply make a video of themselves dumping a bucket of ice water on their heads and then post it on a social media site and challenge others to do the same within 24 hours or make a donation to ALS research (or both).

The stunt, which began early in the summer as a challenge unrelated to amyotrophic lateral sclerosis, has resonated with many people in the dog days of summer and has been helped by many celebrities taking up the challenge. It became linked to ALS when Peter Frates, a 29-year-old man with the disease, took the challenge – albeit by nodding his head to the song "Ice Ice Baby" instead of having ice water dumped on him – and asked others to do the same.

Courtesy Wikimedia Commons/slgckgc/Creative Commons License

According to the ALS Association, as of Aug. 19, existing donors and more than 450,000 new donors have contributed $22.9 million since July 29, compared with $1.9 million during the same period last year. The ALS has a four-out-of-four stars rating on Charity Navigator, and an overall score of 90.73 out of 100. Overall, 72% of its expenses are spent on the programs and services it delivers, 11% on administration, and 17% on fundraising.

Some critics have suggested that the stunt promotes click and post activism, keeping people from doing real activism, or is "narcissism masked as altruism," but most people have embraced it as fun for a good cause.

I asked a few Clinical Neurology News editorial advisory board members to weigh in:

• Dr. Richard J. Caselli, professor of neurology at the Mayo Clinic, Scottsdale, Ariz.: "If it is raising money for ALS research, what’s not to like? Not everyone was destined to be a molecular biologist or clinical trialist, and this gives people a way to contribute that seems to be culturally in synch with the ‘social media’ community. ... The ice water is an interesting twist in that it implies that if you turn a blind eye to this cause you should punish yourself, and I suspect many people harbor feelings of at least slight guilt when they feel they are not contributing to worthwhile needs."

• Matthew Huentelman, Ph.D., associate professor of neurogenomics at the Translational Genomics Research Institute, Phoenix: "If a campaign works (and doesn’t harm) then it is hard to argue against. I think that any awareness campaign that actually gets a response from the White House has probably been a useful one. President Obama confirmed he would be donating but not doing the ice bucket thing. ... I suspect that a lot of research foundations are going to be having ‘tough’ conversations at this month’s board meetings as they compare their awareness and fundraising attempts to the simple ALS ice bucket challenge. It just demonstrates to all of us again that social media is relevant for both spreading the word and getting results. There are a few keys from this too: (1) visual "stuff" matters – short video clips is now how the world communicates; (2) challenging your friends/colleagues by name is important, too – it sort of forces a response from them; and (3) celebs are still key to pushing something viral in a truly short period of time."

(While you contemplate taking the ice bucket challenge, you might as well visit Dr. Huentelman’s social media project, MindCrowd, a site leveraging social media to recruit participants into a brain research study.)

[email protected]

The ALS ice bucket challenge has taken the social media world by storm and surprised many by how fast and far it has spread. People simply make a video of themselves dumping a bucket of ice water on their heads and then post it on a social media site and challenge others to do the same within 24 hours or make a donation to ALS research (or both).

The stunt, which began early in the summer as a challenge unrelated to amyotrophic lateral sclerosis, has resonated with many people in the dog days of summer and has been helped by many celebrities taking up the challenge. It became linked to ALS when Peter Frates, a 29-year-old man with the disease, took the challenge – albeit by nodding his head to the song "Ice Ice Baby" instead of having ice water dumped on him – and asked others to do the same.

Courtesy Wikimedia Commons/slgckgc/Creative Commons License

According to the ALS Association, as of Aug. 19, existing donors and more than 450,000 new donors have contributed $22.9 million since July 29, compared with $1.9 million during the same period last year. The ALS has a four-out-of-four stars rating on Charity Navigator, and an overall score of 90.73 out of 100. Overall, 72% of its expenses are spent on the programs and services it delivers, 11% on administration, and 17% on fundraising.

Some critics have suggested that the stunt promotes click and post activism, keeping people from doing real activism, or is "narcissism masked as altruism," but most people have embraced it as fun for a good cause.

I asked a few Clinical Neurology News editorial advisory board members to weigh in:

• Dr. Richard J. Caselli, professor of neurology at the Mayo Clinic, Scottsdale, Ariz.: "If it is raising money for ALS research, what’s not to like? Not everyone was destined to be a molecular biologist or clinical trialist, and this gives people a way to contribute that seems to be culturally in synch with the ‘social media’ community. ... The ice water is an interesting twist in that it implies that if you turn a blind eye to this cause you should punish yourself, and I suspect many people harbor feelings of at least slight guilt when they feel they are not contributing to worthwhile needs."

• Matthew Huentelman, Ph.D., associate professor of neurogenomics at the Translational Genomics Research Institute, Phoenix: "If a campaign works (and doesn’t harm) then it is hard to argue against. I think that any awareness campaign that actually gets a response from the White House has probably been a useful one. President Obama confirmed he would be donating but not doing the ice bucket thing. ... I suspect that a lot of research foundations are going to be having ‘tough’ conversations at this month’s board meetings as they compare their awareness and fundraising attempts to the simple ALS ice bucket challenge. It just demonstrates to all of us again that social media is relevant for both spreading the word and getting results. There are a few keys from this too: (1) visual "stuff" matters – short video clips is now how the world communicates; (2) challenging your friends/colleagues by name is important, too – it sort of forces a response from them; and (3) celebs are still key to pushing something viral in a truly short period of time."

(While you contemplate taking the ice bucket challenge, you might as well visit Dr. Huentelman’s social media project, MindCrowd, a site leveraging social media to recruit participants into a brain research study.)

[email protected]

Doctor consults with cancer

patient and her father

Credit: Rhoda Baer

Guidelines developed almost 20 years ago can accurately predict infertility in girls with cancer, according to research published in The Lancet Oncology.

Researchers found the criteria in these guidelines can help healthcare professionals select which girls should be given the option of ovarian tissue cryopreservation.

The team noted that taking the initial samples of ovarian tissue involves a surgical technique that is still relatively experimental.

So it is crucial to accurately predict which patients are most likely to benefit from the procedure and when it can be safely performed.

The guidelines, known as the Edinburgh selection criteria, were instituted in 1996 to help healthcare professionals decide which girls should be given the option of cryopreservation, based on their age, type of cancer treatment, and their chance of cure.

Specifically, patients were required to meet the following criteria:

• Age younger than 35 years
• No previous chemotherapy or radiotherapy if 15 years or older at diagnosis, but mild, non-gonadotoxic chemotherapy was acceptable if a patient was younger than 15
• A realistic chance of surviving for 5 years
• A high risk of premature ovarian insufficiency (>50%)
• Informed consent (from parents and the patient, if possible)
• Negative serology results for HIV, syphilis, and hepatitis B
• Not pregnant and no existing children.

Testing the guidelines

To validate the selection criteria, W. Hamish B. Wallace, MD, of the Royal Hospital for Sick Children in Edinburgh, UK, and his colleagues analyzed 410 female cancer patients who were younger than 18 years at their time of diagnosis.

The patients were treated between January 1, 1996, and June 30, 2012, at the Edinburgh Children’s Cancer Centre, which serves the southeast region of Scotland.

In all, 34 patients (8%) met the Edinburgh selection criteria and were given the option of ovarian tissue cryopreservation before starting cancer treatment. Thirteen patients declined, 21 consented, and 20 had a successful procedure.

The researchers were able to assess ovarian function in 14 of the 20 patients with successful cryopreservation and 6 of the 13 patients who declined the procedure.

Of the 14 evaluable patients who underwent cryopreservation, 6 developed premature ovarian insufficiency at a median age of 13.4 years (range, 12.5–14.6), but 1 of these patients also had a natural pregnancy.

One patient each among the 6 evaluable patients who declined cryopreservation and the 141 evaluable patients who were not offered cryopreservation developed premature ovarian insufficiency.

So, overall, the probability of ovarian insufficiency was significantly higher for patients who met the Edinburgh selection criteria than for those who did not. The 15-year probability was 35% and 1%, respectively (P<0.0001).

The researchers said these results validate the use of the selection criteria, as they can accurately identify patients who will likely develop premature ovarian insufficiency.

“Advances in life-saving treatments mean that more and more young people with cancer are surviving the disease,” Dr Wallace said. “Here, we have an opportunity to help young women to have families of their own when they grow up, if they so choose.”

Doctor consults with cancer

patient and her father

Credit: Rhoda Baer

Guidelines developed almost 20 years ago can accurately predict infertility in girls with cancer, according to research published in The Lancet Oncology.

Researchers found the criteria in these guidelines can help healthcare professionals select which girls should be given the option of ovarian tissue cryopreservation.

The team noted that taking the initial samples of ovarian tissue involves a surgical technique that is still relatively experimental.

So it is crucial to accurately predict which patients are most likely to benefit from the procedure and when it can be safely performed.

The guidelines, known as the Edinburgh selection criteria, were instituted in 1996 to help healthcare professionals decide which girls should be given the option of cryopreservation, based on their age, type of cancer treatment, and their chance of cure.

Specifically, patients were required to meet the following criteria:

• Age younger than 35 years
• No previous chemotherapy or radiotherapy if 15 years or older at diagnosis, but mild, non-gonadotoxic chemotherapy was acceptable if a patient was younger than 15
• A realistic chance of surviving for 5 years
• A high risk of premature ovarian insufficiency (>50%)
• Informed consent (from parents and the patient, if possible)
• Negative serology results for HIV, syphilis, and hepatitis B
• Not pregnant and no existing children.

Testing the guidelines

To validate the selection criteria, W. Hamish B. Wallace, MD, of the Royal Hospital for Sick Children in Edinburgh, UK, and his colleagues analyzed 410 female cancer patients who were younger than 18 years at their time of diagnosis.

The patients were treated between January 1, 1996, and June 30, 2012, at the Edinburgh Children’s Cancer Centre, which serves the southeast region of Scotland.

In all, 34 patients (8%) met the Edinburgh selection criteria and were given the option of ovarian tissue cryopreservation before starting cancer treatment. Thirteen patients declined, 21 consented, and 20 had a successful procedure.

The researchers were able to assess ovarian function in 14 of the 20 patients with successful cryopreservation and 6 of the 13 patients who declined the procedure.

Of the 14 evaluable patients who underwent cryopreservation, 6 developed premature ovarian insufficiency at a median age of 13.4 years (range, 12.5–14.6), but 1 of these patients also had a natural pregnancy.

One patient each among the 6 evaluable patients who declined cryopreservation and the 141 evaluable patients who were not offered cryopreservation developed premature ovarian insufficiency.

So, overall, the probability of ovarian insufficiency was significantly higher for patients who met the Edinburgh selection criteria than for those who did not. The 15-year probability was 35% and 1%, respectively (P<0.0001).

The researchers said these results validate the use of the selection criteria, as they can accurately identify patients who will likely develop premature ovarian insufficiency.

“Advances in life-saving treatments mean that more and more young people with cancer are surviving the disease,” Dr Wallace said. “Here, we have an opportunity to help young women to have families of their own when they grow up, if they so choose.”

Doctor consults with cancer

patient and her father

Credit: Rhoda Baer

Guidelines developed almost 20 years ago can accurately predict infertility in girls with cancer, according to research published in The Lancet Oncology.

Researchers found the criteria in these guidelines can help healthcare professionals select which girls should be given the option of ovarian tissue cryopreservation.

The team noted that taking the initial samples of ovarian tissue involves a surgical technique that is still relatively experimental.

So it is crucial to accurately predict which patients are most likely to benefit from the procedure and when it can be safely performed.

The guidelines, known as the Edinburgh selection criteria, were instituted in 1996 to help healthcare professionals decide which girls should be given the option of cryopreservation, based on their age, type of cancer treatment, and their chance of cure.

Specifically, patients were required to meet the following criteria:

• Age younger than 35 years
• No previous chemotherapy or radiotherapy if 15 years or older at diagnosis, but mild, non-gonadotoxic chemotherapy was acceptable if a patient was younger than 15
• A realistic chance of surviving for 5 years
• A high risk of premature ovarian insufficiency (>50%)
• Informed consent (from parents and the patient, if possible)
• Negative serology results for HIV, syphilis, and hepatitis B
• Not pregnant and no existing children.

Testing the guidelines

To validate the selection criteria, W. Hamish B. Wallace, MD, of the Royal Hospital for Sick Children in Edinburgh, UK, and his colleagues analyzed 410 female cancer patients who were younger than 18 years at their time of diagnosis.

The patients were treated between January 1, 1996, and June 30, 2012, at the Edinburgh Children’s Cancer Centre, which serves the southeast region of Scotland.

In all, 34 patients (8%) met the Edinburgh selection criteria and were given the option of ovarian tissue cryopreservation before starting cancer treatment. Thirteen patients declined, 21 consented, and 20 had a successful procedure.

The researchers were able to assess ovarian function in 14 of the 20 patients with successful cryopreservation and 6 of the 13 patients who declined the procedure.

Of the 14 evaluable patients who underwent cryopreservation, 6 developed premature ovarian insufficiency at a median age of 13.4 years (range, 12.5–14.6), but 1 of these patients also had a natural pregnancy.

One patient each among the 6 evaluable patients who declined cryopreservation and the 141 evaluable patients who were not offered cryopreservation developed premature ovarian insufficiency.

So, overall, the probability of ovarian insufficiency was significantly higher for patients who met the Edinburgh selection criteria than for those who did not. The 15-year probability was 35% and 1%, respectively (P<0.0001).

The researchers said these results validate the use of the selection criteria, as they can accurately identify patients who will likely develop premature ovarian insufficiency.

“Advances in life-saving treatments mean that more and more young people with cancer are surviving the disease,” Dr Wallace said. “Here, we have an opportunity to help young women to have families of their own when they grow up, if they so choose.”

Nude mouse

Credit: Armin Kübelbeck

Preclinical experiments may have revealed why some cancer patients do not respond to retinoic acid.

Investigators found that a protein known as AEG-1 blocks the effects of retinoic acid in acute myeloid leukemia (AML) and liver cancer.

They also noted that AEG-1 is overexpressed in nearly every cancer type, so these findings could impact the care of countless cancer patients.

The team reported their findings in Cancer Research.

The group’s experiments revealed that AEG-1 binds to retinoid X receptors (RXR), which help regulate cell growth and development. RXR is typically activated by retinoic acid, but the overexpressed AEG-1 proteins found in cancer cells block these signals and help promote tumor growth.

“Our findings are the first to show that AEG-1 interacts with the retinoid X receptor,” said study author Devanand Sarkar, MBBS, PhD, of Virginia Commonwealth University Massey Cancer Center in Richmond.

Specifically, he and his colleagues found that AEG-1 protected hepatocellular carcinoma cells and AML cells from retinoid- and rexinoid-induced cell death.

But in nude mouse models, blocking the production of AEG-1 allowed all-trans retinoic acid to kill hepatocellular carcinoma cells.

The investigators therefore believe that targeting AEG-1 could sensitize AML patients and those with hepatocellular carcinoma to retinoid- and rexinoid-based therapies.

“This research has immediate clinical relevance, such that physicians could begin screening cancer patients for AEG-1 expression levels in order to determine whether retinoic acid should be prescribed,” Dr Sarkar added.

He and his colleagues have been studying AEG-1 for years. They were the first to create a mouse model demonstrating the role of AEG-1 in liver cancer, and they have been working to develop targeted therapies that block AEG-1 production.

The present study expanded their knowledge of the molecular interactions of AEG-1.

“We are continuing to test combination therapies involving AEG-1 inhibition and retinoic acid in animal models, and the initial results are promising,” Dr Sarkar said. “If we continue to see these results in more complex experiments, we hope to eventually propose a phase 1 clinical trial in patients with liver cancer.”

Nude mouse

Credit: Armin Kübelbeck

Preclinical experiments may have revealed why some cancer patients do not respond to retinoic acid.

Investigators found that a protein known as AEG-1 blocks the effects of retinoic acid in acute myeloid leukemia (AML) and liver cancer.

They also noted that AEG-1 is overexpressed in nearly every cancer type, so these findings could impact the care of countless cancer patients.

The team reported their findings in Cancer Research.

The group’s experiments revealed that AEG-1 binds to retinoid X receptors (RXR), which help regulate cell growth and development. RXR is typically activated by retinoic acid, but the overexpressed AEG-1 proteins found in cancer cells block these signals and help promote tumor growth.

“Our findings are the first to show that AEG-1 interacts with the retinoid X receptor,” said study author Devanand Sarkar, MBBS, PhD, of Virginia Commonwealth University Massey Cancer Center in Richmond.

Specifically, he and his colleagues found that AEG-1 protected hepatocellular carcinoma cells and AML cells from retinoid- and rexinoid-induced cell death.

But in nude mouse models, blocking the production of AEG-1 allowed all-trans retinoic acid to kill hepatocellular carcinoma cells.

The investigators therefore believe that targeting AEG-1 could sensitize AML patients and those with hepatocellular carcinoma to retinoid- and rexinoid-based therapies.

“This research has immediate clinical relevance, such that physicians could begin screening cancer patients for AEG-1 expression levels in order to determine whether retinoic acid should be prescribed,” Dr Sarkar added.

He and his colleagues have been studying AEG-1 for years. They were the first to create a mouse model demonstrating the role of AEG-1 in liver cancer, and they have been working to develop targeted therapies that block AEG-1 production.

The present study expanded their knowledge of the molecular interactions of AEG-1.

“We are continuing to test combination therapies involving AEG-1 inhibition and retinoic acid in animal models, and the initial results are promising,” Dr Sarkar said. “If we continue to see these results in more complex experiments, we hope to eventually propose a phase 1 clinical trial in patients with liver cancer.”

Nude mouse

Credit: Armin Kübelbeck

Preclinical experiments may have revealed why some cancer patients do not respond to retinoic acid.

Investigators found that a protein known as AEG-1 blocks the effects of retinoic acid in acute myeloid leukemia (AML) and liver cancer.

They also noted that AEG-1 is overexpressed in nearly every cancer type, so these findings could impact the care of countless cancer patients.

The team reported their findings in Cancer Research.

The group’s experiments revealed that AEG-1 binds to retinoid X receptors (RXR), which help regulate cell growth and development. RXR is typically activated by retinoic acid, but the overexpressed AEG-1 proteins found in cancer cells block these signals and help promote tumor growth.

“Our findings are the first to show that AEG-1 interacts with the retinoid X receptor,” said study author Devanand Sarkar, MBBS, PhD, of Virginia Commonwealth University Massey Cancer Center in Richmond.

Specifically, he and his colleagues found that AEG-1 protected hepatocellular carcinoma cells and AML cells from retinoid- and rexinoid-induced cell death.

But in nude mouse models, blocking the production of AEG-1 allowed all-trans retinoic acid to kill hepatocellular carcinoma cells.

The investigators therefore believe that targeting AEG-1 could sensitize AML patients and those with hepatocellular carcinoma to retinoid- and rexinoid-based therapies.

“This research has immediate clinical relevance, such that physicians could begin screening cancer patients for AEG-1 expression levels in order to determine whether retinoic acid should be prescribed,” Dr Sarkar added.

He and his colleagues have been studying AEG-1 for years. They were the first to create a mouse model demonstrating the role of AEG-1 in liver cancer, and they have been working to develop targeted therapies that block AEG-1 production.

The present study expanded their knowledge of the molecular interactions of AEG-1.

“We are continuing to test combination therapies involving AEG-1 inhibition and retinoic acid in animal models, and the initial results are promising,” Dr Sarkar said. “If we continue to see these results in more complex experiments, we hope to eventually propose a phase 1 clinical trial in patients with liver cancer.”

P falciparum gametocytes

Credit: Swiss TPH

Malaria parasites exploit the epigenetic regulator HP1 to promote their survival and transmission between human hosts, a new study suggests.

It appears that Plasmodium falciparum uses HP1 to control the expression of surface antigens and escape the body’s immune responses. This prolongs the parasite’s survival and enables its transmission.

Researchers believe this discovery paves the way for new strategies to prevent malaria transmission.

Till Voss, PhD, of the Swiss Tropical and Public Health Institute in Basel, and his colleagues detailed the discovery in Cell Host & Microbe.

The team knew that HP1 induces heritable condensation of chromosomal regions. As a result, genes located within these regions are not expressed.

Since this conformation is reversible, HP1-controlled genes can become activated without requiring changes in the underlying DNA sequence.

With this in mind, the researchers engineered a mutant P falciparum parasite in which HP1 expression can be shut down. And the team observed that, in HP1-depleted parasites, all of the 60 var genes became highly active.

Each var gene encodes a distinct variant of the virulence factor PfEMP1, which is displayed on the surface of the parasite-infected red blood cell. PfEMP1 is a major target of the immune system in infected humans.

Individual parasites normally express only 1 of the 60 var/PfEMP1 proteins, while keeping all other members silenced. By switching to another var/PfEMP1 variant, the parasite is able to escape existing immune responses raised against previous variants.

Dr Voss and his colleagues found that HP1 protects the PfEMP1 antigenic repertoire from being exposed to the immune system all at once.

“This finding is a major step forward in understanding the complex mechanisms responsible for antigenic variation,” Dr Voss said. “Furthermore, the tools generated in our study may be relevant for future research on malaria vaccines and immunity.”

The researchers also found that parasites lacking HP1 fail to copy their genomes and are therefore unable to proliferate. Initially, this led the team to believe that all the parasites they had cultured were dead.

However, more than 50% of these parasites turned out to be fully viable and differentiated into gametocytes, the sexual form of the malaria parasite. Gametocytes are the only form of the parasite capable of infecting a mosquito and are a prerequisite to transmit malaria between humans.

“Such a high sexual conversion rate is unprecedented,” Dr Voss said. “Usually, only around 1% of parasites undergo this switch.”

Further experiments revealed that a master transcription factor triggering sexual differentiation—AP2-G—is expressed at much higher levels in parasites lacking HP1. Under normal conditions, HP1 silences the expression of AP2-G and therefore prevents sexual conversion in most parasites.

“The switch from parasite proliferation to gametocyte differentiation is controlled epigenetically by an HP1-dependent mechanism,” Dr Voss said.

“With this knowledge in hand, and with the identification of another epigenetic regulator involved in the same process [also published in Cell Host & Microbe], we are now able to specifically track the sexual conversion pathway in molecular detail.”

This may enable the development of new drugs to prevent sexual conversion and, consequently, malaria transmission.

P falciparum gametocytes

Credit: Swiss TPH

Malaria parasites exploit the epigenetic regulator HP1 to promote their survival and transmission between human hosts, a new study suggests.

It appears that Plasmodium falciparum uses HP1 to control the expression of surface antigens and escape the body’s immune responses. This prolongs the parasite’s survival and enables its transmission.

Researchers believe this discovery paves the way for new strategies to prevent malaria transmission.

Till Voss, PhD, of the Swiss Tropical and Public Health Institute in Basel, and his colleagues detailed the discovery in Cell Host & Microbe.

The team knew that HP1 induces heritable condensation of chromosomal regions. As a result, genes located within these regions are not expressed.

Since this conformation is reversible, HP1-controlled genes can become activated without requiring changes in the underlying DNA sequence.

With this in mind, the researchers engineered a mutant P falciparum parasite in which HP1 expression can be shut down. And the team observed that, in HP1-depleted parasites, all of the 60 var genes became highly active.

Each var gene encodes a distinct variant of the virulence factor PfEMP1, which is displayed on the surface of the parasite-infected red blood cell. PfEMP1 is a major target of the immune system in infected humans.

Individual parasites normally express only 1 of the 60 var/PfEMP1 proteins, while keeping all other members silenced. By switching to another var/PfEMP1 variant, the parasite is able to escape existing immune responses raised against previous variants.

Dr Voss and his colleagues found that HP1 protects the PfEMP1 antigenic repertoire from being exposed to the immune system all at once.

“This finding is a major step forward in understanding the complex mechanisms responsible for antigenic variation,” Dr Voss said. “Furthermore, the tools generated in our study may be relevant for future research on malaria vaccines and immunity.”

The researchers also found that parasites lacking HP1 fail to copy their genomes and are therefore unable to proliferate. Initially, this led the team to believe that all the parasites they had cultured were dead.

However, more than 50% of these parasites turned out to be fully viable and differentiated into gametocytes, the sexual form of the malaria parasite. Gametocytes are the only form of the parasite capable of infecting a mosquito and are a prerequisite to transmit malaria between humans.

“Such a high sexual conversion rate is unprecedented,” Dr Voss said. “Usually, only around 1% of parasites undergo this switch.”

Further experiments revealed that a master transcription factor triggering sexual differentiation—AP2-G—is expressed at much higher levels in parasites lacking HP1. Under normal conditions, HP1 silences the expression of AP2-G and therefore prevents sexual conversion in most parasites.

“The switch from parasite proliferation to gametocyte differentiation is controlled epigenetically by an HP1-dependent mechanism,” Dr Voss said.

“With this knowledge in hand, and with the identification of another epigenetic regulator involved in the same process [also published in Cell Host & Microbe], we are now able to specifically track the sexual conversion pathway in molecular detail.”

This may enable the development of new drugs to prevent sexual conversion and, consequently, malaria transmission.

P falciparum gametocytes

Credit: Swiss TPH

Malaria parasites exploit the epigenetic regulator HP1 to promote their survival and transmission between human hosts, a new study suggests.

It appears that Plasmodium falciparum uses HP1 to control the expression of surface antigens and escape the body’s immune responses. This prolongs the parasite’s survival and enables its transmission.

Researchers believe this discovery paves the way for new strategies to prevent malaria transmission.

Till Voss, PhD, of the Swiss Tropical and Public Health Institute in Basel, and his colleagues detailed the discovery in Cell Host & Microbe.

The team knew that HP1 induces heritable condensation of chromosomal regions. As a result, genes located within these regions are not expressed.

Since this conformation is reversible, HP1-controlled genes can become activated without requiring changes in the underlying DNA sequence.

With this in mind, the researchers engineered a mutant P falciparum parasite in which HP1 expression can be shut down. And the team observed that, in HP1-depleted parasites, all of the 60 var genes became highly active.

Each var gene encodes a distinct variant of the virulence factor PfEMP1, which is displayed on the surface of the parasite-infected red blood cell. PfEMP1 is a major target of the immune system in infected humans.

Individual parasites normally express only 1 of the 60 var/PfEMP1 proteins, while keeping all other members silenced. By switching to another var/PfEMP1 variant, the parasite is able to escape existing immune responses raised against previous variants.

Dr Voss and his colleagues found that HP1 protects the PfEMP1 antigenic repertoire from being exposed to the immune system all at once.

“This finding is a major step forward in understanding the complex mechanisms responsible for antigenic variation,” Dr Voss said. “Furthermore, the tools generated in our study may be relevant for future research on malaria vaccines and immunity.”

The researchers also found that parasites lacking HP1 fail to copy their genomes and are therefore unable to proliferate. Initially, this led the team to believe that all the parasites they had cultured were dead.

However, more than 50% of these parasites turned out to be fully viable and differentiated into gametocytes, the sexual form of the malaria parasite. Gametocytes are the only form of the parasite capable of infecting a mosquito and are a prerequisite to transmit malaria between humans.

“Such a high sexual conversion rate is unprecedented,” Dr Voss said. “Usually, only around 1% of parasites undergo this switch.”

Further experiments revealed that a master transcription factor triggering sexual differentiation—AP2-G—is expressed at much higher levels in parasites lacking HP1. Under normal conditions, HP1 silences the expression of AP2-G and therefore prevents sexual conversion in most parasites.

“The switch from parasite proliferation to gametocyte differentiation is controlled epigenetically by an HP1-dependent mechanism,” Dr Voss said.

“With this knowledge in hand, and with the identification of another epigenetic regulator involved in the same process [also published in Cell Host & Microbe], we are now able to specifically track the sexual conversion pathway in molecular detail.”

This may enable the development of new drugs to prevent sexual conversion and, consequently, malaria transmission.

Nick Huntington, PhD

Credit: Walter and Eliza Hall

Institute of Medical Research

New research suggests the Mcl-1 protein is crucial for the survival of natural killer (NK) cells and, therefore, innate immune responses.

Researchers deleted Mcl-1 from NK cells in mice and observed a loss of the cells from all tissues.

This made the mice more receptive to allogeneic hematopoietic stem cell transplants and resistant to toxic shock following a sepsis challenge, but it also made the mice susceptible to melanoma metastases.

The researchers believe their findings, published in Nature Communications, will help to determine how NK cells can be manipulated to treat a range of disorders.

They said Mcl-1 could be a target for boosting or depleting NK cell populations when necessary.

The researchers first discovered that Mcl-1 is highly expressed in NK cells. And Mcl-1 is regulated by IL-15 in a dose-dependent manner via STAT5 phosphorylation and subsequent binding to the 3′-UTR of Mcl-1.

“We showed Mcl-1 levels inside the cell increase in response to [IL-15],” said study author Nick Huntington, PhD, of the Walter and Eliza Hall Institute of Medical Research in Victoria, Australia.

“We previously knew IL-15 boosted production and survival of natural killer cells, and we have shown that IL-15 does this by initiating a cascade of signals that tell the natural killer cell to produce Mcl-1 to keep it alive.”

To further explore this phenomenon, the researchers deleted Mcl-1 from NK cells in mice and observed depletion of the cells in all tissues. The team said this was the result of a failure to antagonize pro-apoptotic proteins in the outer mitochondrial membrane.

Additional experiments showed that the mice needed the NK cells to fight off invading melanoma cells that had spread past the original cancer site.

“Without natural killer cells, the body was unable to destroy melanoma metastases that had spread throughout the body, and the cancers overwhelmed the lungs,” Dr Huntington said.

However, the loss of NK cells also made mice more receptive to allogeneic stem cell transplants and resistant to toxic shock after polymicrobial sepsis challenge.

“Natural killer cells led the response that caused rejection of donor stem cells in bone marrow transplantations,” Dr Huntington said. “They also produced inflammatory signals that can result in toxic shock syndrome, a potentially fatal illness caused by bacterial toxins that causes a whole-body inflammatory reaction.”

The researchers said these results clearly show a non-redundant pathway linking IL-15 to Mcl-1 in the maintenance of NK cells and innate immune responses.

Dr Huntington said the discovery provides a solid lead to look for ways of boosting or depleting NK cells when necessary.

“Now that we know the critical importance of Mcl-1 in the survival of natural killer cells,” he said, “we are investigating how we might manipulate this protein, or other proteins in the pathway, to treat disease.”

Nick Huntington, PhD

Credit: Walter and Eliza Hall

Institute of Medical Research

New research suggests the Mcl-1 protein is crucial for the survival of natural killer (NK) cells and, therefore, innate immune responses.

Researchers deleted Mcl-1 from NK cells in mice and observed a loss of the cells from all tissues.

This made the mice more receptive to allogeneic hematopoietic stem cell transplants and resistant to toxic shock following a sepsis challenge, but it also made the mice susceptible to melanoma metastases.

The researchers believe their findings, published in Nature Communications, will help to determine how NK cells can be manipulated to treat a range of disorders.

They said Mcl-1 could be a target for boosting or depleting NK cell populations when necessary.

The researchers first discovered that Mcl-1 is highly expressed in NK cells. And Mcl-1 is regulated by IL-15 in a dose-dependent manner via STAT5 phosphorylation and subsequent binding to the 3′-UTR of Mcl-1.

“We showed Mcl-1 levels inside the cell increase in response to [IL-15],” said study author Nick Huntington, PhD, of the Walter and Eliza Hall Institute of Medical Research in Victoria, Australia.

“We previously knew IL-15 boosted production and survival of natural killer cells, and we have shown that IL-15 does this by initiating a cascade of signals that tell the natural killer cell to produce Mcl-1 to keep it alive.”

To further explore this phenomenon, the researchers deleted Mcl-1 from NK cells in mice and observed depletion of the cells in all tissues. The team said this was the result of a failure to antagonize pro-apoptotic proteins in the outer mitochondrial membrane.

Additional experiments showed that the mice needed the NK cells to fight off invading melanoma cells that had spread past the original cancer site.

“Without natural killer cells, the body was unable to destroy melanoma metastases that had spread throughout the body, and the cancers overwhelmed the lungs,” Dr Huntington said.

However, the loss of NK cells also made mice more receptive to allogeneic stem cell transplants and resistant to toxic shock after polymicrobial sepsis challenge.

“Natural killer cells led the response that caused rejection of donor stem cells in bone marrow transplantations,” Dr Huntington said. “They also produced inflammatory signals that can result in toxic shock syndrome, a potentially fatal illness caused by bacterial toxins that causes a whole-body inflammatory reaction.”

The researchers said these results clearly show a non-redundant pathway linking IL-15 to Mcl-1 in the maintenance of NK cells and innate immune responses.

Dr Huntington said the discovery provides a solid lead to look for ways of boosting or depleting NK cells when necessary.

“Now that we know the critical importance of Mcl-1 in the survival of natural killer cells,” he said, “we are investigating how we might manipulate this protein, or other proteins in the pathway, to treat disease.”

Nick Huntington, PhD

Credit: Walter and Eliza Hall

Institute of Medical Research

New research suggests the Mcl-1 protein is crucial for the survival of natural killer (NK) cells and, therefore, innate immune responses.

Researchers deleted Mcl-1 from NK cells in mice and observed a loss of the cells from all tissues.

This made the mice more receptive to allogeneic hematopoietic stem cell transplants and resistant to toxic shock following a sepsis challenge, but it also made the mice susceptible to melanoma metastases.

The researchers believe their findings, published in Nature Communications, will help to determine how NK cells can be manipulated to treat a range of disorders.

They said Mcl-1 could be a target for boosting or depleting NK cell populations when necessary.

The researchers first discovered that Mcl-1 is highly expressed in NK cells. And Mcl-1 is regulated by IL-15 in a dose-dependent manner via STAT5 phosphorylation and subsequent binding to the 3′-UTR of Mcl-1.

“We showed Mcl-1 levels inside the cell increase in response to [IL-15],” said study author Nick Huntington, PhD, of the Walter and Eliza Hall Institute of Medical Research in Victoria, Australia.

“We previously knew IL-15 boosted production and survival of natural killer cells, and we have shown that IL-15 does this by initiating a cascade of signals that tell the natural killer cell to produce Mcl-1 to keep it alive.”

To further explore this phenomenon, the researchers deleted Mcl-1 from NK cells in mice and observed depletion of the cells in all tissues. The team said this was the result of a failure to antagonize pro-apoptotic proteins in the outer mitochondrial membrane.

Additional experiments showed that the mice needed the NK cells to fight off invading melanoma cells that had spread past the original cancer site.

“Without natural killer cells, the body was unable to destroy melanoma metastases that had spread throughout the body, and the cancers overwhelmed the lungs,” Dr Huntington said.

However, the loss of NK cells also made mice more receptive to allogeneic stem cell transplants and resistant to toxic shock after polymicrobial sepsis challenge.

“Natural killer cells led the response that caused rejection of donor stem cells in bone marrow transplantations,” Dr Huntington said. “They also produced inflammatory signals that can result in toxic shock syndrome, a potentially fatal illness caused by bacterial toxins that causes a whole-body inflammatory reaction.”

The researchers said these results clearly show a non-redundant pathway linking IL-15 to Mcl-1 in the maintenance of NK cells and innate immune responses.

Dr Huntington said the discovery provides a solid lead to look for ways of boosting or depleting NK cells when necessary.

“Now that we know the critical importance of Mcl-1 in the survival of natural killer cells,” he said, “we are investigating how we might manipulate this protein, or other proteins in the pathway, to treat disease.”