In cohort A, median time to first response was 0.99 months (range, 0.7 to 3.3) and median time to best response was 3.25 months (range, 0.9 to 13.6), with a 24-month duration of response (DOR) rate of 73.3% , while cohort B demonstrated median times of 0.95 months (range, 0.9 to 9.7) and 5.1 months (range, 0.9 to 11.8), with a 24-month DOR rate of 70.5%.
At that time of the median follow-up the overall survival (OS; time patients live before death of any cause), progression-free survival (PFS; time patients live before their disease worsening), and duration of response (DOR) were not estimable in both cohorts. However, the 24-month OS rates in cohorts A and B were 75% and 84.2%, respectively, and the 24-month PFS rates were 75% and 73.3%.
There were no new safety signals reported; however, one neurotoxicity event occurred in cohort B. Regarding grade 3 and 4 (moderate to severe) side effects of special interest, two patients (10%) in cohort A and 1 patient (5.3%) in cohort B experienced cytokine release syndrome (CRS; when the body releases too many inflammatory molecules, called cytokines, into the blood). The median time to onset of CRS was seven days in cohort A and eight days in cohort B, and the median duration was three and four days, respectively.
Other grade 3 and 4 treatment-emergent side effects in cohorts A and B included CAR T-cell neurotoxicity (5% and 5.3%, respectively) and other neurotoxicity (5% and 5.3%). Movement and neurocognitive were found only in cohort B (5.3%), and second primary malignancy was also found only in cohort B (5.3%).
Overall, cytopenia-related grade 3 and 4 side effects in cohorts A and B were neutropenia (95% and 89.5%, respectively), lymphopenia (80% and 47.4%), thrombocytopenia (40% and 26.3%), anemia (45% and 47.4%) and leukopenia (60% and 31.6%).
Patients in cohort A had 1 to 3 prior lines of therapy and were lenalidomide (Revlimid) refractory MM, while patients in cohort B had experienced early relapse of less than 12 months after autologous stem cell transplant (ASCT) or the start of antimyeloma treatment if no transplant was conducted.Specifically in cohort B, 16% of patients had high-risk cytogenetic abnormalities, 79% were refractory to their last lines of therapy, 16% had triple-class refractory disease and 79% had prior ASCT.
The median age was 60 years in cohort A and 58 years in cohort B, and the majority of patients were male in both cohorts (65% and 73.7%, respectively). Regarding race, 90% were White and 10% were Black in cohort A, compared with 73.7% and 10.5%, respectively cohort B.
“We believe these [data] show that early introduction of cilta-cel in these patient cohorts is promising, and CARTITUDE-4 trial has also done a phase 3 study evaluating these early lines of therapy,” Hillengass stated.“Cohort A provides insight into longer-term survival outcomes that may be expected in the CARTITUDE-4 trial and cohort B data highlight the durable efficacy of cilta-cel in patients with early relapse where there is unmet need.”
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