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The co-opting and weakening of the immune system by hematologic malignancies and many of their treatments – and the blunting of the immune system’s response to vaccines – may be more salient during the COVID-19 pandemic than ever before.
Hematologic malignancies have been associated in large cancer-and-COVID-19 registries with more severe COVID-19 outcomes than solid tumors, and COVID-19 mRNA vaccines have yielded suboptimal responses across multiple studies. Clinicians and researchers have no shortage of questions, like what is the optimal timing of vaccines relative to cancer-directed therapy? What is the durability and impact of the immune response? What is the status of the immune system in patients who do not produce antispike antibodies after COVID-19 vaccination?
Moreover, will there be novel nonvaccine strategies – such as antibody cocktails or convalescent plasma – to ensure protection against COVID-19 and other future viral threats? And what really defines immunocompromise today and moving forward?
“We don’t know what we don’t know,” said Jeremy L. Warner, MD, associate professor of medicine (hematology/oncology) and biomedical informatics at Vanderbilt University, Nashville, Tenn., and cofounder of the international COVID-19 and Cancer Consortium. “The immune system is incredibly complex and there are numerous defenses, in addition to the humoral response that we routinely measure.”
Another of the pressing pandemic-time questions for infectious disease specialists working in cancer centers concerns a different infectious threat: measles. “There is a lot of concern in this space about the reported drop in childhood vaccinations and the possibility of measles outbreaks as a follow-up to COVID-19,” said Steven A. Pergam, MD, MPH, associate professor in the vaccine and infectious disease division and the clinical research division of the Fred Hutchinson Cancer Research Center, Seattle Cancer Care Alliance.
Whether recipients of hematopoietic cell transplantation (HCT) and cellular therapy should be revaccinated earlier than 2 years post treatment is a question worthy of preemptive discussion, he said.
What about timing?
“A silver lining of the pandemic is that it’s improving our understanding of response to vaccinations and outcomes with respiratory viruses in patients with hematologic malignancies,” said Samuel Rubinstein, MD, of the division of hematology at the University of North Carolina at Chapel Hill. “We’re going to learn a lot more about how to ensure that our patients are optimally protected from respiratory viruses.”
Dr. Rubinstein focuses on plasma cell disorders, mostly multiple myeloma, and routinely explains to patients consenting to use daratumumab, an anti-CD38 monoclonal antibody, or a BCMA-directed therapy, that these therapies “in particular probably do impair vaccine immune response.”
He has handled the timing of the COVID-19 vaccines – currently boosters, in most cases – as he has with influenza and other immunizations such as the pneumococcal vaccine, administering the vaccines agnostic to therapy unless the patient is about to start daratumumab or a BCMA-directed therapy. In this case, he considers vaccinating and waiting 2 weeks (for an immune response to occur) before starting therapy.
However, “if I have any concern that a delay will result in suboptimal cancer control, then I don’t wait,” Dr. Rubinstein said. Poor control of a primary malignancy has been consistently associated with worse COVID-19–specific outcomes in cancer–COVID-19 studies, he said, including an analysis of almost 5,000 patients recorded to the COVID-19 and Cancer Consortium .1
(The analysis also documented that patients with a hematologic malignancy had an odds ratio of higher COVID-19 severity of 1.7, compared with patients with a solid tumor, and an odds ratio of 30-day mortality of 1.44.)
Ideally, said Dr. Warner, patients will get vaccinated with the COVID-19 vaccines or others, “before starting on any cytotoxic chemotherapy and when they do not have low blood counts or perhaps autoimmune complications of immunotherapy.” However, “perfect being the enemy of good, it’s better to get vaccinated than to wait for the exact ideal time.”
Peter Paul Yu, MD, physician-in-chief at Hartford (Conn.) Healthcare Cancer Institute, said that for most patients, there’s no evidence to support an optimal timing of vaccine administration during the chemotherapy cycle. “We looked into that [to guide administration of the COVID-19 vaccines], thinking there might be some data about influenza vaccination,” he said. “But there isn’t much. … And if we make things more complicated than the evidence suggests, we may have fewer people getting vaccinations.”
The National Comprehensive Cancer Network offered several timing recommendations in its August 2021 COVID-19 vaccination guidance – mainly that patients receiving intensive cytotoxic chemotherapy (such as those on cytarabine/anthracycline-based induction regimens for acute myeloid leukemia) delay COVID-19 vaccination until absolute neutrophil count recovery, and that patients on long-term maintenance therapy (for instance, targeted agents for chronic lymphocytic leukemia or myeloproliferative neoplasms) be vaccinated as soon as possible.
Vaccination should be delayed for at least 3 months, the NCCN noted, following HCT or engineered cell therapy (for example, chimeric antigen receptor [CAR] T cells) “in order to maximize vaccine efficacy.”
More known unknowns
The tempered efficacy of the COVID-19 vaccines in patients with hematologic malignancies “has been shown in multiple studies of multiple myeloma, chronic lymphocytic leukemia (CLL), and other malignancies, and we know it’s true in transplant,” said Dr. Pergam.
In a study of 67 patients with hematologic malignancies at the University of Pittsburgh Medical Center Hillman Cancer Center, for instance, 46.3% did not generate IgG antibodies against the SARS-CoV-2 spike protein receptor–binding domain after completing their two-dose mRNA vaccine series. Patients with B-cell CLL were especially unlikely to develop antibodies.2A much larger study of more than 1,400 patients from investigators at the Mayo Clinics in Rochester, Minn., and Jacksonville, Fla., found that approximately 25% of all patients with hematologic malignancies did not produce antispike IgG antibodies, and that those with the most common B-cell malignancies had the lowest rate of seropositivity (44%-79%).3There’s a clear but challenging delineation between antibody testing in the research space and in clinical practice, however. Various national and cancer societies recommended earlier this year against routine postvaccine serological monitoring outside of clinical trials, and the sources interviewed for this story all emphasized that antibody titer measurements should not guide decisions about boosters or about the precautions advised for patients.
Titers checked at a single point in time do not capture the kinetics, multidimensional nature, or durability of an immune response, Dr. Warner said. “There are papers out there that say zero patients with CCL seroconverted … but they do still have some immunity, and maybe even a lot of immunity.”
Antibody testing can create a false sense of security, or a false sense of dread, he said. Yet in practice, the use of serological monitoring “has been all over the place [with] no consistency … and decisions probably being made at the individual clinic level or health system level,” he said.
To a lesser degree, so have definitions of what composes significant immunocompromise in the context of COVID-19 vaccine eligibility. “The question comes up, what does immunocompromised really mean?” said Dr. Yu, whose institution is a member of the Memorial Sloan Kettering (MSK) Cancer Alliance.
As of September, the MSK Cancer Center had taken a more granular approach to describing moderate to severe immunocompromise than did the Centers for Disease Control and Prevention. The CDC said this level of immunocompromise includes people receiving active cancer treatment for tumors or cancers of the blood, and those who’ve received a stem cell transplant within the past 2 years. MSK extended the recommendation, as it concerns hematologic malignancies, to patients who are within 12 months after treatment with B-cell depleting drugs, patients who have been treated for blood cancers within the last 6 months, and patients who received CAR T therapy within the past 2 years.
Dr. Yu, who was not involved in creating the MSK recommendations for third COVID-19 vaccines, said that he has been thinking more broadly during the pandemic about the notion of immunocompetence. “It’s my opinion that patients with hematologic malignancies, even if they’re not on treatment, are not fully immune competent,” he said. This includes patients with CLL stage 0 and patients with plasma cell dyscrasias who don’t yet meet the criteria for multiple myeloma but have a monoclonal gammopathy, and those with lower-risk myelodysplastic syndromes, he said.
“We’re seeing [variable] recommendations based on expert opinion, and I think that’s justifiable in such a dynamic situation,” Dr. Yu said. “I would [even] argue it’s desirable so we can learn from different approaches” and collect more rigorous observational data.
Immunocompetence needs to be “viewed in the context of the threat,” he added. “COVID changes the equation. … What’s immunocompromised in my mind has changed [from prepandemic times].”
Preparing for measles
Measles lit up on Dr. Pergam’s radar screen in 2019, when an outbreak occurred in nearby Clark County, Wash. This and other outbreaks in New York, California, and other states highlighted declines in measles herd immunity in the United States and prompted him to investigate the seroprevalence of measles antibodies in the Fred Hutchinson Cancer Research Center’s outpatient population.
Of 959 consecutive patients seen at the center, they found, 25% lacked protective antibodies for measles. For patients with hematologic malignancies and those with a history of HCT, seroprevalence was worse: 37% and 54%, respectively, were without the IgG antibodies.4 Measles “is the most contagious human virus we have at the moment,” he said, and “revaccinating people is hard when it comes to cancer because it is a live virus vaccine.”
Vaccine hesitancy, a rise in nonmedical exemptions, and other factors were threatening herd immunity before the pandemic began. Now, with declines in routine childhood medical visits and other vaccination opportunities and resources here and in other countries – and declining immunization rates documented by the CDC in May 2021 – the pandemic has made measles outbreaks more likely, he said. (Measles outbreaks in West Africa on the tail end of the Ebola outbreak in 2014-2015 caused more deaths in children than Ebola, he noted.)
The first priority is vaccination “cocooning,” a strategy that has long been important for patients with hematologic malignancies. But it also possible, Dr. Pergam said, that in the setting of any future community transmission, revaccination for HCT recipients could occur earlier than the standard 2-year post-transplantation recommendation.
In a 2019 position statement endorsed by the American Society for Transplantation and Cellular Therapy, Dr. Pergam and other infectious disease physicians and oncologists provide criteria for considering early revaccination on a case-by-case basis for patients on minimal immunosuppressive therapy who are at least 1-year post transplantation.5
“Our thinking was that there may be lower-risk patients to whom we could offer the vaccine” – patients for whom the risk of developing measles might outweigh the risk of potential vaccine-related complications, he said.
And if there were community cases, he added, there might be a place for testing antibody levels in post-transplant patients, however imperfect the window to immunity may be. “We’re thinking through potential scenarios,” he said. “Oncologists should think about measles again and have it on their back burner.”
References
1. Grivas P et al. Ann Oncol. 2021 Jun;32(6):787-800.
2. Agha ME et al. Open Forum Infect Dis. 2021 July;8(7):ofab353.
3. Greenberger LM et al. Cancer Cell. 2021 Aug 9;39(8):1031-3.
4. Marquis SR et al. JAMA Netw Open. 2021 July;4(7):e2118508.
5. Pergam SA et al. Biol Blood Marrow Transplant. 2019 Nov;25:e321-30.
The co-opting and weakening of the immune system by hematologic malignancies and many of their treatments – and the blunting of the immune system’s response to vaccines – may be more salient during the COVID-19 pandemic than ever before.
Hematologic malignancies have been associated in large cancer-and-COVID-19 registries with more severe COVID-19 outcomes than solid tumors, and COVID-19 mRNA vaccines have yielded suboptimal responses across multiple studies. Clinicians and researchers have no shortage of questions, like what is the optimal timing of vaccines relative to cancer-directed therapy? What is the durability and impact of the immune response? What is the status of the immune system in patients who do not produce antispike antibodies after COVID-19 vaccination?
Moreover, will there be novel nonvaccine strategies – such as antibody cocktails or convalescent plasma – to ensure protection against COVID-19 and other future viral threats? And what really defines immunocompromise today and moving forward?
“We don’t know what we don’t know,” said Jeremy L. Warner, MD, associate professor of medicine (hematology/oncology) and biomedical informatics at Vanderbilt University, Nashville, Tenn., and cofounder of the international COVID-19 and Cancer Consortium. “The immune system is incredibly complex and there are numerous defenses, in addition to the humoral response that we routinely measure.”
Another of the pressing pandemic-time questions for infectious disease specialists working in cancer centers concerns a different infectious threat: measles. “There is a lot of concern in this space about the reported drop in childhood vaccinations and the possibility of measles outbreaks as a follow-up to COVID-19,” said Steven A. Pergam, MD, MPH, associate professor in the vaccine and infectious disease division and the clinical research division of the Fred Hutchinson Cancer Research Center, Seattle Cancer Care Alliance.
Whether recipients of hematopoietic cell transplantation (HCT) and cellular therapy should be revaccinated earlier than 2 years post treatment is a question worthy of preemptive discussion, he said.
What about timing?
“A silver lining of the pandemic is that it’s improving our understanding of response to vaccinations and outcomes with respiratory viruses in patients with hematologic malignancies,” said Samuel Rubinstein, MD, of the division of hematology at the University of North Carolina at Chapel Hill. “We’re going to learn a lot more about how to ensure that our patients are optimally protected from respiratory viruses.”
Dr. Rubinstein focuses on plasma cell disorders, mostly multiple myeloma, and routinely explains to patients consenting to use daratumumab, an anti-CD38 monoclonal antibody, or a BCMA-directed therapy, that these therapies “in particular probably do impair vaccine immune response.”
He has handled the timing of the COVID-19 vaccines – currently boosters, in most cases – as he has with influenza and other immunizations such as the pneumococcal vaccine, administering the vaccines agnostic to therapy unless the patient is about to start daratumumab or a BCMA-directed therapy. In this case, he considers vaccinating and waiting 2 weeks (for an immune response to occur) before starting therapy.
However, “if I have any concern that a delay will result in suboptimal cancer control, then I don’t wait,” Dr. Rubinstein said. Poor control of a primary malignancy has been consistently associated with worse COVID-19–specific outcomes in cancer–COVID-19 studies, he said, including an analysis of almost 5,000 patients recorded to the COVID-19 and Cancer Consortium .1
(The analysis also documented that patients with a hematologic malignancy had an odds ratio of higher COVID-19 severity of 1.7, compared with patients with a solid tumor, and an odds ratio of 30-day mortality of 1.44.)
Ideally, said Dr. Warner, patients will get vaccinated with the COVID-19 vaccines or others, “before starting on any cytotoxic chemotherapy and when they do not have low blood counts or perhaps autoimmune complications of immunotherapy.” However, “perfect being the enemy of good, it’s better to get vaccinated than to wait for the exact ideal time.”
Peter Paul Yu, MD, physician-in-chief at Hartford (Conn.) Healthcare Cancer Institute, said that for most patients, there’s no evidence to support an optimal timing of vaccine administration during the chemotherapy cycle. “We looked into that [to guide administration of the COVID-19 vaccines], thinking there might be some data about influenza vaccination,” he said. “But there isn’t much. … And if we make things more complicated than the evidence suggests, we may have fewer people getting vaccinations.”
The National Comprehensive Cancer Network offered several timing recommendations in its August 2021 COVID-19 vaccination guidance – mainly that patients receiving intensive cytotoxic chemotherapy (such as those on cytarabine/anthracycline-based induction regimens for acute myeloid leukemia) delay COVID-19 vaccination until absolute neutrophil count recovery, and that patients on long-term maintenance therapy (for instance, targeted agents for chronic lymphocytic leukemia or myeloproliferative neoplasms) be vaccinated as soon as possible.
Vaccination should be delayed for at least 3 months, the NCCN noted, following HCT or engineered cell therapy (for example, chimeric antigen receptor [CAR] T cells) “in order to maximize vaccine efficacy.”
More known unknowns
The tempered efficacy of the COVID-19 vaccines in patients with hematologic malignancies “has been shown in multiple studies of multiple myeloma, chronic lymphocytic leukemia (CLL), and other malignancies, and we know it’s true in transplant,” said Dr. Pergam.
In a study of 67 patients with hematologic malignancies at the University of Pittsburgh Medical Center Hillman Cancer Center, for instance, 46.3% did not generate IgG antibodies against the SARS-CoV-2 spike protein receptor–binding domain after completing their two-dose mRNA vaccine series. Patients with B-cell CLL were especially unlikely to develop antibodies.2A much larger study of more than 1,400 patients from investigators at the Mayo Clinics in Rochester, Minn., and Jacksonville, Fla., found that approximately 25% of all patients with hematologic malignancies did not produce antispike IgG antibodies, and that those with the most common B-cell malignancies had the lowest rate of seropositivity (44%-79%).3There’s a clear but challenging delineation between antibody testing in the research space and in clinical practice, however. Various national and cancer societies recommended earlier this year against routine postvaccine serological monitoring outside of clinical trials, and the sources interviewed for this story all emphasized that antibody titer measurements should not guide decisions about boosters or about the precautions advised for patients.
Titers checked at a single point in time do not capture the kinetics, multidimensional nature, or durability of an immune response, Dr. Warner said. “There are papers out there that say zero patients with CCL seroconverted … but they do still have some immunity, and maybe even a lot of immunity.”
Antibody testing can create a false sense of security, or a false sense of dread, he said. Yet in practice, the use of serological monitoring “has been all over the place [with] no consistency … and decisions probably being made at the individual clinic level or health system level,” he said.
To a lesser degree, so have definitions of what composes significant immunocompromise in the context of COVID-19 vaccine eligibility. “The question comes up, what does immunocompromised really mean?” said Dr. Yu, whose institution is a member of the Memorial Sloan Kettering (MSK) Cancer Alliance.
As of September, the MSK Cancer Center had taken a more granular approach to describing moderate to severe immunocompromise than did the Centers for Disease Control and Prevention. The CDC said this level of immunocompromise includes people receiving active cancer treatment for tumors or cancers of the blood, and those who’ve received a stem cell transplant within the past 2 years. MSK extended the recommendation, as it concerns hematologic malignancies, to patients who are within 12 months after treatment with B-cell depleting drugs, patients who have been treated for blood cancers within the last 6 months, and patients who received CAR T therapy within the past 2 years.
Dr. Yu, who was not involved in creating the MSK recommendations for third COVID-19 vaccines, said that he has been thinking more broadly during the pandemic about the notion of immunocompetence. “It’s my opinion that patients with hematologic malignancies, even if they’re not on treatment, are not fully immune competent,” he said. This includes patients with CLL stage 0 and patients with plasma cell dyscrasias who don’t yet meet the criteria for multiple myeloma but have a monoclonal gammopathy, and those with lower-risk myelodysplastic syndromes, he said.
“We’re seeing [variable] recommendations based on expert opinion, and I think that’s justifiable in such a dynamic situation,” Dr. Yu said. “I would [even] argue it’s desirable so we can learn from different approaches” and collect more rigorous observational data.
Immunocompetence needs to be “viewed in the context of the threat,” he added. “COVID changes the equation. … What’s immunocompromised in my mind has changed [from prepandemic times].”
Preparing for measles
Measles lit up on Dr. Pergam’s radar screen in 2019, when an outbreak occurred in nearby Clark County, Wash. This and other outbreaks in New York, California, and other states highlighted declines in measles herd immunity in the United States and prompted him to investigate the seroprevalence of measles antibodies in the Fred Hutchinson Cancer Research Center’s outpatient population.
Of 959 consecutive patients seen at the center, they found, 25% lacked protective antibodies for measles. For patients with hematologic malignancies and those with a history of HCT, seroprevalence was worse: 37% and 54%, respectively, were without the IgG antibodies.4 Measles “is the most contagious human virus we have at the moment,” he said, and “revaccinating people is hard when it comes to cancer because it is a live virus vaccine.”
Vaccine hesitancy, a rise in nonmedical exemptions, and other factors were threatening herd immunity before the pandemic began. Now, with declines in routine childhood medical visits and other vaccination opportunities and resources here and in other countries – and declining immunization rates documented by the CDC in May 2021 – the pandemic has made measles outbreaks more likely, he said. (Measles outbreaks in West Africa on the tail end of the Ebola outbreak in 2014-2015 caused more deaths in children than Ebola, he noted.)
The first priority is vaccination “cocooning,” a strategy that has long been important for patients with hematologic malignancies. But it also possible, Dr. Pergam said, that in the setting of any future community transmission, revaccination for HCT recipients could occur earlier than the standard 2-year post-transplantation recommendation.
In a 2019 position statement endorsed by the American Society for Transplantation and Cellular Therapy, Dr. Pergam and other infectious disease physicians and oncologists provide criteria for considering early revaccination on a case-by-case basis for patients on minimal immunosuppressive therapy who are at least 1-year post transplantation.5
“Our thinking was that there may be lower-risk patients to whom we could offer the vaccine” – patients for whom the risk of developing measles might outweigh the risk of potential vaccine-related complications, he said.
And if there were community cases, he added, there might be a place for testing antibody levels in post-transplant patients, however imperfect the window to immunity may be. “We’re thinking through potential scenarios,” he said. “Oncologists should think about measles again and have it on their back burner.”
References
1. Grivas P et al. Ann Oncol. 2021 Jun;32(6):787-800.
2. Agha ME et al. Open Forum Infect Dis. 2021 July;8(7):ofab353.
3. Greenberger LM et al. Cancer Cell. 2021 Aug 9;39(8):1031-3.
4. Marquis SR et al. JAMA Netw Open. 2021 July;4(7):e2118508.
5. Pergam SA et al. Biol Blood Marrow Transplant. 2019 Nov;25:e321-30.
The co-opting and weakening of the immune system by hematologic malignancies and many of their treatments – and the blunting of the immune system’s response to vaccines – may be more salient during the COVID-19 pandemic than ever before.
Hematologic malignancies have been associated in large cancer-and-COVID-19 registries with more severe COVID-19 outcomes than solid tumors, and COVID-19 mRNA vaccines have yielded suboptimal responses across multiple studies. Clinicians and researchers have no shortage of questions, like what is the optimal timing of vaccines relative to cancer-directed therapy? What is the durability and impact of the immune response? What is the status of the immune system in patients who do not produce antispike antibodies after COVID-19 vaccination?
Moreover, will there be novel nonvaccine strategies – such as antibody cocktails or convalescent plasma – to ensure protection against COVID-19 and other future viral threats? And what really defines immunocompromise today and moving forward?
“We don’t know what we don’t know,” said Jeremy L. Warner, MD, associate professor of medicine (hematology/oncology) and biomedical informatics at Vanderbilt University, Nashville, Tenn., and cofounder of the international COVID-19 and Cancer Consortium. “The immune system is incredibly complex and there are numerous defenses, in addition to the humoral response that we routinely measure.”
Another of the pressing pandemic-time questions for infectious disease specialists working in cancer centers concerns a different infectious threat: measles. “There is a lot of concern in this space about the reported drop in childhood vaccinations and the possibility of measles outbreaks as a follow-up to COVID-19,” said Steven A. Pergam, MD, MPH, associate professor in the vaccine and infectious disease division and the clinical research division of the Fred Hutchinson Cancer Research Center, Seattle Cancer Care Alliance.
Whether recipients of hematopoietic cell transplantation (HCT) and cellular therapy should be revaccinated earlier than 2 years post treatment is a question worthy of preemptive discussion, he said.
What about timing?
“A silver lining of the pandemic is that it’s improving our understanding of response to vaccinations and outcomes with respiratory viruses in patients with hematologic malignancies,” said Samuel Rubinstein, MD, of the division of hematology at the University of North Carolina at Chapel Hill. “We’re going to learn a lot more about how to ensure that our patients are optimally protected from respiratory viruses.”
Dr. Rubinstein focuses on plasma cell disorders, mostly multiple myeloma, and routinely explains to patients consenting to use daratumumab, an anti-CD38 monoclonal antibody, or a BCMA-directed therapy, that these therapies “in particular probably do impair vaccine immune response.”
He has handled the timing of the COVID-19 vaccines – currently boosters, in most cases – as he has with influenza and other immunizations such as the pneumococcal vaccine, administering the vaccines agnostic to therapy unless the patient is about to start daratumumab or a BCMA-directed therapy. In this case, he considers vaccinating and waiting 2 weeks (for an immune response to occur) before starting therapy.
However, “if I have any concern that a delay will result in suboptimal cancer control, then I don’t wait,” Dr. Rubinstein said. Poor control of a primary malignancy has been consistently associated with worse COVID-19–specific outcomes in cancer–COVID-19 studies, he said, including an analysis of almost 5,000 patients recorded to the COVID-19 and Cancer Consortium .1
(The analysis also documented that patients with a hematologic malignancy had an odds ratio of higher COVID-19 severity of 1.7, compared with patients with a solid tumor, and an odds ratio of 30-day mortality of 1.44.)
Ideally, said Dr. Warner, patients will get vaccinated with the COVID-19 vaccines or others, “before starting on any cytotoxic chemotherapy and when they do not have low blood counts or perhaps autoimmune complications of immunotherapy.” However, “perfect being the enemy of good, it’s better to get vaccinated than to wait for the exact ideal time.”
Peter Paul Yu, MD, physician-in-chief at Hartford (Conn.) Healthcare Cancer Institute, said that for most patients, there’s no evidence to support an optimal timing of vaccine administration during the chemotherapy cycle. “We looked into that [to guide administration of the COVID-19 vaccines], thinking there might be some data about influenza vaccination,” he said. “But there isn’t much. … And if we make things more complicated than the evidence suggests, we may have fewer people getting vaccinations.”
The National Comprehensive Cancer Network offered several timing recommendations in its August 2021 COVID-19 vaccination guidance – mainly that patients receiving intensive cytotoxic chemotherapy (such as those on cytarabine/anthracycline-based induction regimens for acute myeloid leukemia) delay COVID-19 vaccination until absolute neutrophil count recovery, and that patients on long-term maintenance therapy (for instance, targeted agents for chronic lymphocytic leukemia or myeloproliferative neoplasms) be vaccinated as soon as possible.
Vaccination should be delayed for at least 3 months, the NCCN noted, following HCT or engineered cell therapy (for example, chimeric antigen receptor [CAR] T cells) “in order to maximize vaccine efficacy.”
More known unknowns
The tempered efficacy of the COVID-19 vaccines in patients with hematologic malignancies “has been shown in multiple studies of multiple myeloma, chronic lymphocytic leukemia (CLL), and other malignancies, and we know it’s true in transplant,” said Dr. Pergam.
In a study of 67 patients with hematologic malignancies at the University of Pittsburgh Medical Center Hillman Cancer Center, for instance, 46.3% did not generate IgG antibodies against the SARS-CoV-2 spike protein receptor–binding domain after completing their two-dose mRNA vaccine series. Patients with B-cell CLL were especially unlikely to develop antibodies.2A much larger study of more than 1,400 patients from investigators at the Mayo Clinics in Rochester, Minn., and Jacksonville, Fla., found that approximately 25% of all patients with hematologic malignancies did not produce antispike IgG antibodies, and that those with the most common B-cell malignancies had the lowest rate of seropositivity (44%-79%).3There’s a clear but challenging delineation between antibody testing in the research space and in clinical practice, however. Various national and cancer societies recommended earlier this year against routine postvaccine serological monitoring outside of clinical trials, and the sources interviewed for this story all emphasized that antibody titer measurements should not guide decisions about boosters or about the precautions advised for patients.
Titers checked at a single point in time do not capture the kinetics, multidimensional nature, or durability of an immune response, Dr. Warner said. “There are papers out there that say zero patients with CCL seroconverted … but they do still have some immunity, and maybe even a lot of immunity.”
Antibody testing can create a false sense of security, or a false sense of dread, he said. Yet in practice, the use of serological monitoring “has been all over the place [with] no consistency … and decisions probably being made at the individual clinic level or health system level,” he said.
To a lesser degree, so have definitions of what composes significant immunocompromise in the context of COVID-19 vaccine eligibility. “The question comes up, what does immunocompromised really mean?” said Dr. Yu, whose institution is a member of the Memorial Sloan Kettering (MSK) Cancer Alliance.
As of September, the MSK Cancer Center had taken a more granular approach to describing moderate to severe immunocompromise than did the Centers for Disease Control and Prevention. The CDC said this level of immunocompromise includes people receiving active cancer treatment for tumors or cancers of the blood, and those who’ve received a stem cell transplant within the past 2 years. MSK extended the recommendation, as it concerns hematologic malignancies, to patients who are within 12 months after treatment with B-cell depleting drugs, patients who have been treated for blood cancers within the last 6 months, and patients who received CAR T therapy within the past 2 years.
Dr. Yu, who was not involved in creating the MSK recommendations for third COVID-19 vaccines, said that he has been thinking more broadly during the pandemic about the notion of immunocompetence. “It’s my opinion that patients with hematologic malignancies, even if they’re not on treatment, are not fully immune competent,” he said. This includes patients with CLL stage 0 and patients with plasma cell dyscrasias who don’t yet meet the criteria for multiple myeloma but have a monoclonal gammopathy, and those with lower-risk myelodysplastic syndromes, he said.
“We’re seeing [variable] recommendations based on expert opinion, and I think that’s justifiable in such a dynamic situation,” Dr. Yu said. “I would [even] argue it’s desirable so we can learn from different approaches” and collect more rigorous observational data.
Immunocompetence needs to be “viewed in the context of the threat,” he added. “COVID changes the equation. … What’s immunocompromised in my mind has changed [from prepandemic times].”
Preparing for measles
Measles lit up on Dr. Pergam’s radar screen in 2019, when an outbreak occurred in nearby Clark County, Wash. This and other outbreaks in New York, California, and other states highlighted declines in measles herd immunity in the United States and prompted him to investigate the seroprevalence of measles antibodies in the Fred Hutchinson Cancer Research Center’s outpatient population.
Of 959 consecutive patients seen at the center, they found, 25% lacked protective antibodies for measles. For patients with hematologic malignancies and those with a history of HCT, seroprevalence was worse: 37% and 54%, respectively, were without the IgG antibodies.4 Measles “is the most contagious human virus we have at the moment,” he said, and “revaccinating people is hard when it comes to cancer because it is a live virus vaccine.”
Vaccine hesitancy, a rise in nonmedical exemptions, and other factors were threatening herd immunity before the pandemic began. Now, with declines in routine childhood medical visits and other vaccination opportunities and resources here and in other countries – and declining immunization rates documented by the CDC in May 2021 – the pandemic has made measles outbreaks more likely, he said. (Measles outbreaks in West Africa on the tail end of the Ebola outbreak in 2014-2015 caused more deaths in children than Ebola, he noted.)
The first priority is vaccination “cocooning,” a strategy that has long been important for patients with hematologic malignancies. But it also possible, Dr. Pergam said, that in the setting of any future community transmission, revaccination for HCT recipients could occur earlier than the standard 2-year post-transplantation recommendation.
In a 2019 position statement endorsed by the American Society for Transplantation and Cellular Therapy, Dr. Pergam and other infectious disease physicians and oncologists provide criteria for considering early revaccination on a case-by-case basis for patients on minimal immunosuppressive therapy who are at least 1-year post transplantation.5
“Our thinking was that there may be lower-risk patients to whom we could offer the vaccine” – patients for whom the risk of developing measles might outweigh the risk of potential vaccine-related complications, he said.
And if there were community cases, he added, there might be a place for testing antibody levels in post-transplant patients, however imperfect the window to immunity may be. “We’re thinking through potential scenarios,” he said. “Oncologists should think about measles again and have it on their back burner.”
References
1. Grivas P et al. Ann Oncol. 2021 Jun;32(6):787-800.
2. Agha ME et al. Open Forum Infect Dis. 2021 July;8(7):ofab353.
3. Greenberger LM et al. Cancer Cell. 2021 Aug 9;39(8):1031-3.
4. Marquis SR et al. JAMA Netw Open. 2021 July;4(7):e2118508.
5. Pergam SA et al. Biol Blood Marrow Transplant. 2019 Nov;25:e321-30.