Posted: Friday, June 10, 2022
According to a 4-year follow-up of a phase II trial, presented at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract 7540), a fixed-duration treatment regimen of obinutuzumab, ibrutinib, and venetoclax continued to yield durable remission rates for patients with chronic lymphocytic leukemia (CLL). Kerry Anne Rogers, MD, of The Ohio State University, Columbus, and colleagues concluded that the safety and efficacy profiles of the triplet regimen justified further study and will be compared with ibrutinib plus obinutuzumab in two phase III cooperative group trials.
In this phase II study, the authors divided 75 patients with CLL into three cohorts: two of treatment-naive patients (25 each) and one of 25 patients with relapsed or refractory CLL. All patients received obinutuzumab, ibrutinib, and venetoclax in 14 28-day cycles. The patients began taking obinutuzumab in cycle 1, ibrutinib in cycle 2, and venetoclax in cycle 3.
For the second cohort of treatment-naive patients, the overall response rate after 14 cycles of treatment was 96%, including a complete remission with an undetectable measurable residual disease (MRD) rate of 20%. The combined overall response rate for both treatment-naive groups was 90%, including a complete remission with an undetectable MRD rate of 24%.
After a median follow-up of 56 months, one patient died in each cohort. There were six cases of disease progression—four in the relapsed and refractory group and two in the first treatment-naive cohort—and no cases in the second treatment-naive group. The estimated 48-month progression-free survival rates for the first treatment-naive cohort and relapsed/refractory cohorts were both 96%, with overall survival rates of 85% and 100%, respectively. The second treatment-naive cohort had a 48-month progression-free survival rate of 96% and an overall survival rate of 96%.
The most frequent adverse events for all groups were neutropenia (95%), leukopenia (93%), and thrombocytopenia (91%). The only grade 3 or higher nonhematologic toxicity that occurred at a rate greater than 20% was hypertension (85%).
Disclosure: For full disclosures of the study authors, visit coi.asco.org.