SAN DIEGO – Ibrutinib treatment continued before, during, and after infusion of the CD19-specific chimeric antigen receptor (CAR) T-cell therapy JCAR014 in patients with relapsed or refractory chronic lymphocytic leukemia (CLL) appears to improve patient responses and decrease the risk of severe cytokine release syndrome.
The findings come from a comparison of sequential cohorts from a phase 1/2 study.
At 4 weeks after infusion, the approach was highly efficacious; overall response rates by 2008 International Workshop on CLL (IWCLL) criteria were 83% in 24 patients who received the uninterrupted ibrutinib regimen along with the JCAR014 therapy – a combination of CD4 and CD8 T cells – and 65% in 19 patients from a prior cohort who did not receive continuous ibrutinib, Jordan Gauthier, MD, reported at the annual meeting of the American Society of Hematology.
Concurrent ibrutinib was generally well tolerated, with 13 of 19 patients in the ibrutinib cohort receiving treatment as planned without discontinuation. The rates of grade 1 or higher cytokine release syndrome (CRS) were statistically similar in the ibrutinib and no-ibrutinib cohorts (74% and 92%, respectively). However, the rates of severe CRS (grade 3 or higher) were, strikingly, 0% and 25%, respectively, said, a senior fellow in the Turtle Lab at Fred Hutchinson Cancer Center, Seattle.
Neurotoxicity occurred in 32% and 42% of patients in the groups; severe neurotoxicity occurred in 26% and 29%, respectively.
In the ibrutinib cohort, one patient with grade 2 CRS developed fatal presumed cardiac arrhythmia; in the no-ibrutinib cohort, one patient died from a CAR T cell–related toxicity.
Notably, a trend toward better expansion of CD8 CAR T cells and a significantly greater expansion of CD4 CAR T cells was observed in the ibrutinib cohort, he said.
The study was designed to assess JCAR014, and based on the initial cohort findingsin 2017, established a regimen of cyclophosphamide and fludarabine (Cy/Flu) lymphodepletion followed by JCAR014 infusion at 2 x 106 CAR T cells/kg. The study was not a randomized, head-to-head comparison but the groups were similar with respect to both patient and disease characteristics, Dr. Gauthier noted.
The outcomes in the first cohort were then compared retrospectively with those from the subsequent cohort of patients who received Cy/Flu with 2 x 106 CAR T cells/kg with concurrent ibrutinib administered at 420 mg per day from at least 2 weeks prior to leukapheresis until at least 3 months after JCAR014 infusion.
The rationale for uninterrupted ibrutinib in relapsed/refractory CLL patients receiving JCAR014 included potential prevention of tumor flare, mobilization of CLL cells into the blood from the lymph nodes, improvement of CAR T-cell function, and a decrease in CAR T-cell related toxicity, he said.
The concurrent administration of ibrutinib and JCAR014 was feasible for most patients. “[It] induced high response rates and deep responses early on at 4 weeks, and it was associated with higher in vivo expansion of CD4 CAR T cells and with lower rates of severe toxicity,” Dr. Gauthier said. “The next step is to hopefully validate these findings in a prospective phase 1/2 study.”
Dr. Gauthier reported having no financial disclosures.
SOURCE: Gauthier J et al. ASH 18, .