Experimental CARS therapy breaks through relapsed CLL

ATLANTA – Responses to chimeric antigen receptor–modified T-cell therapy have been sustained beyond 2 years in a small cohort of patients with advanced chronic lymphocytic leukemia and no other curable options.

Three patients remain in complete remission at 7, 27, and 28 months, with no evidence of disease in their blood or bone marrow and complete resolution of all abnormal adenopathy.

Partial responses have been reported in four patients, including two with no evidence of CLL in their blood and bone marrow and more than a 50% reduction in bulky nodes at 2 and 3 months’ follow-up. The two other partial responders were treated earlier with an older vector lot that may not have been as potent, and had responses lasting approximately 4 months, Dr. David Porter said at the annual meeting of the American Society of Hematology.

Two of the nine evaluable patients had no response, for an overall response rate of 78%. Another patient was treated too recently to evaluate.

The findings represent a potential paradigm shift in the treatment of blood cancers, particularly for patients with advanced disease or with high-risk features. These patients are incurable except by allogeneic bone marrow or stem cell transplants, which are associated with extensive morbidity and mortality, he said.

In previous trials of chimeric antigen receptor (CAR) T cells, responses were modest and in vivo proliferation of the modified cells was not sustained. Investigators at the Hospital of the University of Pennsylvania, Philadelphia, then developed a second-generation CAR that targeted the B-cell antigen CD19, but was also linked to the CD3-zeta and CD137 (4-1BB) signaling domains. Preclinical observations showed that CD137 promotes the persistence of antigen-specific and antigen-nonspecific CAR T cells.

A pilot study reported a complete response within 3 weeks of treatment with the genetically modified T cells in a patient with advanced chronic lymphoid leukemia, who remains in remission today (N. Engl. J. Med. 2011;365:725-33). The therapy also resulted in the recovery of a 6-year-old with acute lymphoblastic leukemia as recently reported in the New York Times.

"So it’s now been in a definitive medical journal," quipped Dr. Porter.

On a more serious note, he acknowledged that in addition to its curative potential, "there is significant toxicity associated with this therapy." Five responders experienced grade 3-4 hepatotoxicity, with one patient on transient dialysis on several occasions for renal failure related to tumor lysis syndrome and hypotension.

Persistent B-cell aplasia with hypogammaglobulinemia developed in all patients achieving a complete remission, although treatment with intravenous immunoglobulin has been successful in preventing excessive or frequent infections.

In addition, all responding patients developed a rather profound cytokine release syndrome at the time of T-cell expansion, manifested by very high fevers, nausea, hypotension, and even capillary leak and hypoxia, said Dr. Porter, director of the blood and marrow transplantation program at the hospital.

Research revealed high levels of interleukin (IL)-6 (6-400x), interferon-gamma (89-1000), and IL-2R (5-25), but no significant increase in tumor necrosis factor–alpha or IL-2. Steroids reversed the syndrome in one patient. Given the cytokine profile, however, the switch was made to anticytokine therapy with tocilizumab (Actemra).

Cytokine release syndrome "can be treated effectively with anticytokine therapy, but what we don’t know is whether earlier treatment for the cytokine release syndrome is going to abrogate the T-cell activity and response," Dr. Porter said.

The 10 adult patients he reported had CD19-positive CLL that had been treated with at least two prior therapies (median 5; range 2-10) and progressed within 2 years of the last treatment. Three patients had the high-risk deletion 17p. Their median age was 66 years.

The patients received lympho-depleting chemotherapy 4-7 days before reinfusion with their genetically modified T cells using a lentivirus vector. The median cell dose was 7.5 x 10⁸ (range 1.7-50 x 10⁸), the infused dose of modified T cells was 1.4 x 10⁸ per kilogram, and the median follow-up was 8 months. There was no significant infusion-related toxicity, Dr. Porter said.

Responders experienced a massive expansion of T cells – 1,000- to 10,000-fold in vivo. This translated into a 2-log expansion in patients with a partial response and more than a 3-log expansion in complete responders. The expansion was associated with tumor lysis syndrome in complete responders.

The cells are at very high numbers early on after therapy, representing almost 15% of all the CD3-positive cells at 12 months and 1.2% at 18 months. The two long-term patients have levels of about 1% at 2 years, he said.

Deep whole transcriptome sequencing revealed no evidence of minimal residual disease in patients with a complete response.

The term "serial killer cells" has been coined because there has been an effector-to-target ratio of 1 in 1,000 to 1 in 93,000, meaning that the infused T cells, or their progeny, can kill up to 93,000 tumor cells, Dr. Porter said.

"When we do the math, we estimate that’s between 2.9 and 7.5 pounds of tumor in these patients that we’ve treated," he added.

During a discussion of the results, Dr. Porter said that in patients with cytokine release syndrome, anti-IL-6 therapy is typically given at the first sign of hemodynamic instability and that improvement is almost instantaneous. To address the B-cell dysplasia, he said, there is a lot of interest in developing either more specific targets or technology such as a suicide vector where the CARS are self-limited to allow for normal B-cell development.

In August 2012, the University of Pennsylvania and Novartis announced an exclusive global research and licensing agreement to study and commercialize CAR therapies for other cancers at a Center for Advanced Cellular Therapies to be built on the university campus.

The research was supported in part by grants from the National Institutes of Health, the Leukemia and Lymphoma Society, and the Alliance for Cancer Gene Therapy. Dr. Porter reported patents and royalties from Novartis, honoraria from Celgene, spouse employment with Genentech, and research funding from Pfizer. His coauthors reported commercial relationships with TxCell and Novartis.

[email protected]

ATLANTA – Responses to chimeric antigen receptor–modified T-cell therapy have been sustained beyond 2 years in a small cohort of patients with advanced chronic lymphocytic leukemia and no other curable options.

Three patients remain in complete remission at 7, 27, and 28 months, with no evidence of disease in their blood or bone marrow and complete resolution of all abnormal adenopathy.

Partial responses have been reported in four patients, including two with no evidence of CLL in their blood and bone marrow and more than a 50% reduction in bulky nodes at 2 and 3 months’ follow-up. The two other partial responders were treated earlier with an older vector lot that may not have been as potent, and had responses lasting approximately 4 months, Dr. David Porter said at the annual meeting of the American Society of Hematology.

Two of the nine evaluable patients had no response, for an overall response rate of 78%. Another patient was treated too recently to evaluate.

The findings represent a potential paradigm shift in the treatment of blood cancers, particularly for patients with advanced disease or with high-risk features. These patients are incurable except by allogeneic bone marrow or stem cell transplants, which are associated with extensive morbidity and mortality, he said.

In previous trials of chimeric antigen receptor (CAR) T cells, responses were modest and in vivo proliferation of the modified cells was not sustained. Investigators at the Hospital of the University of Pennsylvania, Philadelphia, then developed a second-generation CAR that targeted the B-cell antigen CD19, but was also linked to the CD3-zeta and CD137 (4-1BB) signaling domains. Preclinical observations showed that CD137 promotes the persistence of antigen-specific and antigen-nonspecific CAR T cells.

A pilot study reported a complete response within 3 weeks of treatment with the genetically modified T cells in a patient with advanced chronic lymphoid leukemia, who remains in remission today (N. Engl. J. Med. 2011;365:725-33). The therapy also resulted in the recovery of a 6-year-old with acute lymphoblastic leukemia as recently reported in the New York Times.

"So it’s now been in a definitive medical journal," quipped Dr. Porter.

On a more serious note, he acknowledged that in addition to its curative potential, "there is significant toxicity associated with this therapy." Five responders experienced grade 3-4 hepatotoxicity, with one patient on transient dialysis on several occasions for renal failure related to tumor lysis syndrome and hypotension.

Persistent B-cell aplasia with hypogammaglobulinemia developed in all patients achieving a complete remission, although treatment with intravenous immunoglobulin has been successful in preventing excessive or frequent infections.

In addition, all responding patients developed a rather profound cytokine release syndrome at the time of T-cell expansion, manifested by very high fevers, nausea, hypotension, and even capillary leak and hypoxia, said Dr. Porter, director of the blood and marrow transplantation program at the hospital.

Research revealed high levels of interleukin (IL)-6 (6-400x), interferon-gamma (89-1000), and IL-2R (5-25), but no significant increase in tumor necrosis factor–alpha or IL-2. Steroids reversed the syndrome in one patient. Given the cytokine profile, however, the switch was made to anticytokine therapy with tocilizumab (Actemra).

Cytokine release syndrome "can be treated effectively with anticytokine therapy, but what we don’t know is whether earlier treatment for the cytokine release syndrome is going to abrogate the T-cell activity and response," Dr. Porter said.

The 10 adult patients he reported had CD19-positive CLL that had been treated with at least two prior therapies (median 5; range 2-10) and progressed within 2 years of the last treatment. Three patients had the high-risk deletion 17p. Their median age was 66 years.

The patients received lympho-depleting chemotherapy 4-7 days before reinfusion with their genetically modified T cells using a lentivirus vector. The median cell dose was 7.5 x 10⁸ (range 1.7-50 x 10⁸), the infused dose of modified T cells was 1.4 x 10⁸ per kilogram, and the median follow-up was 8 months. There was no significant infusion-related toxicity, Dr. Porter said.

Responders experienced a massive expansion of T cells – 1,000- to 10,000-fold in vivo. This translated into a 2-log expansion in patients with a partial response and more than a 3-log expansion in complete responders. The expansion was associated with tumor lysis syndrome in complete responders.

The cells are at very high numbers early on after therapy, representing almost 15% of all the CD3-positive cells at 12 months and 1.2% at 18 months. The two long-term patients have levels of about 1% at 2 years, he said.

Deep whole transcriptome sequencing revealed no evidence of minimal residual disease in patients with a complete response.

The term "serial killer cells" has been coined because there has been an effector-to-target ratio of 1 in 1,000 to 1 in 93,000, meaning that the infused T cells, or their progeny, can kill up to 93,000 tumor cells, Dr. Porter said.

"When we do the math, we estimate that’s between 2.9 and 7.5 pounds of tumor in these patients that we’ve treated," he added.

During a discussion of the results, Dr. Porter said that in patients with cytokine release syndrome, anti-IL-6 therapy is typically given at the first sign of hemodynamic instability and that improvement is almost instantaneous. To address the B-cell dysplasia, he said, there is a lot of interest in developing either more specific targets or technology such as a suicide vector where the CARS are self-limited to allow for normal B-cell development.

In August 2012, the University of Pennsylvania and Novartis announced an exclusive global research and licensing agreement to study and commercialize CAR therapies for other cancers at a Center for Advanced Cellular Therapies to be built on the university campus.

The research was supported in part by grants from the National Institutes of Health, the Leukemia and Lymphoma Society, and the Alliance for Cancer Gene Therapy. Dr. Porter reported patents and royalties from Novartis, honoraria from Celgene, spouse employment with Genentech, and research funding from Pfizer. His coauthors reported commercial relationships with TxCell and Novartis.

[email protected]

ATLANTA – Responses to chimeric antigen receptor–modified T-cell therapy have been sustained beyond 2 years in a small cohort of patients with advanced chronic lymphocytic leukemia and no other curable options.

Three patients remain in complete remission at 7, 27, and 28 months, with no evidence of disease in their blood or bone marrow and complete resolution of all abnormal adenopathy.

Partial responses have been reported in four patients, including two with no evidence of CLL in their blood and bone marrow and more than a 50% reduction in bulky nodes at 2 and 3 months’ follow-up. The two other partial responders were treated earlier with an older vector lot that may not have been as potent, and had responses lasting approximately 4 months, Dr. David Porter said at the annual meeting of the American Society of Hematology.

Two of the nine evaluable patients had no response, for an overall response rate of 78%. Another patient was treated too recently to evaluate.

The findings represent a potential paradigm shift in the treatment of blood cancers, particularly for patients with advanced disease or with high-risk features. These patients are incurable except by allogeneic bone marrow or stem cell transplants, which are associated with extensive morbidity and mortality, he said.

In previous trials of chimeric antigen receptor (CAR) T cells, responses were modest and in vivo proliferation of the modified cells was not sustained. Investigators at the Hospital of the University of Pennsylvania, Philadelphia, then developed a second-generation CAR that targeted the B-cell antigen CD19, but was also linked to the CD3-zeta and CD137 (4-1BB) signaling domains. Preclinical observations showed that CD137 promotes the persistence of antigen-specific and antigen-nonspecific CAR T cells.

A pilot study reported a complete response within 3 weeks of treatment with the genetically modified T cells in a patient with advanced chronic lymphoid leukemia, who remains in remission today (N. Engl. J. Med. 2011;365:725-33). The therapy also resulted in the recovery of a 6-year-old with acute lymphoblastic leukemia as recently reported in the New York Times.

"So it’s now been in a definitive medical journal," quipped Dr. Porter.

On a more serious note, he acknowledged that in addition to its curative potential, "there is significant toxicity associated with this therapy." Five responders experienced grade 3-4 hepatotoxicity, with one patient on transient dialysis on several occasions for renal failure related to tumor lysis syndrome and hypotension.

Persistent B-cell aplasia with hypogammaglobulinemia developed in all patients achieving a complete remission, although treatment with intravenous immunoglobulin has been successful in preventing excessive or frequent infections.

In addition, all responding patients developed a rather profound cytokine release syndrome at the time of T-cell expansion, manifested by very high fevers, nausea, hypotension, and even capillary leak and hypoxia, said Dr. Porter, director of the blood and marrow transplantation program at the hospital.

Research revealed high levels of interleukin (IL)-6 (6-400x), interferon-gamma (89-1000), and IL-2R (5-25), but no significant increase in tumor necrosis factor–alpha or IL-2. Steroids reversed the syndrome in one patient. Given the cytokine profile, however, the switch was made to anticytokine therapy with tocilizumab (Actemra).

Cytokine release syndrome "can be treated effectively with anticytokine therapy, but what we don’t know is whether earlier treatment for the cytokine release syndrome is going to abrogate the T-cell activity and response," Dr. Porter said.

The 10 adult patients he reported had CD19-positive CLL that had been treated with at least two prior therapies (median 5; range 2-10) and progressed within 2 years of the last treatment. Three patients had the high-risk deletion 17p. Their median age was 66 years.

The patients received lympho-depleting chemotherapy 4-7 days before reinfusion with their genetically modified T cells using a lentivirus vector. The median cell dose was 7.5 x 10⁸ (range 1.7-50 x 10⁸), the infused dose of modified T cells was 1.4 x 10⁸ per kilogram, and the median follow-up was 8 months. There was no significant infusion-related toxicity, Dr. Porter said.

Responders experienced a massive expansion of T cells – 1,000- to 10,000-fold in vivo. This translated into a 2-log expansion in patients with a partial response and more than a 3-log expansion in complete responders. The expansion was associated with tumor lysis syndrome in complete responders.

The cells are at very high numbers early on after therapy, representing almost 15% of all the CD3-positive cells at 12 months and 1.2% at 18 months. The two long-term patients have levels of about 1% at 2 years, he said.

Deep whole transcriptome sequencing revealed no evidence of minimal residual disease in patients with a complete response.

The term "serial killer cells" has been coined because there has been an effector-to-target ratio of 1 in 1,000 to 1 in 93,000, meaning that the infused T cells, or their progeny, can kill up to 93,000 tumor cells, Dr. Porter said.

"When we do the math, we estimate that’s between 2.9 and 7.5 pounds of tumor in these patients that we’ve treated," he added.

During a discussion of the results, Dr. Porter said that in patients with cytokine release syndrome, anti-IL-6 therapy is typically given at the first sign of hemodynamic instability and that improvement is almost instantaneous. To address the B-cell dysplasia, he said, there is a lot of interest in developing either more specific targets or technology such as a suicide vector where the CARS are self-limited to allow for normal B-cell development.

In August 2012, the University of Pennsylvania and Novartis announced an exclusive global research and licensing agreement to study and commercialize CAR therapies for other cancers at a Center for Advanced Cellular Therapies to be built on the university campus.

The research was supported in part by grants from the National Institutes of Health, the Leukemia and Lymphoma Society, and the Alliance for Cancer Gene Therapy. Dr. Porter reported patents and royalties from Novartis, honoraria from Celgene, spouse employment with Genentech, and research funding from Pfizer. His coauthors reported commercial relationships with TxCell and Novartis.

[email protected]