Size of CLL Population Creates Limitations for Subgroup Analyses

William G. Wierda, MD, PhD, D. B. Lane Cancer Research Distinguished Professor, section chief of Chronic Lymphocytic Leukemia, and center medical director in the Department of Leukemia, Division of Cancer Medicine, and executive medical director of The University of Texas MD Anderson Cancer Center, discusses challenges faced in when investigating ibrutinib (Imbruvica) and venetoclax (Venclexta) in the CAPTIVATE trial (NCT02910583) for patients with chronic lymphocytic leukemia (CLL).

Researchers in this setting are interested in finding out who the high-risk patients are, who are most likely to respond, and who are more likely to have minimal residual disease (MRD) negative status. Wierda says that, the patient numbers are limited, so subgroup analyses and reports on factors that correlate with the likelihood of achieving undetectable MRD or longer disease-free survival can’t be reported. Though with further follow-up data along with combining the analysis of the MRD cohort and fixed-duration cohort in the CAPTIVATE trial, this may be possible.

The fixed-duration cohort was a similar size to the MRD cohort; a large group of about 150 patients who got fixed-duration treatment only. Patients received 3 months of single-agent ibrutinib, followed by 12 cycles of combined therapy. All the patients stopped treatment after the 12 cycles of ibrutinib and venetoclax. In total, there will be more than 300 patients evaluable for a subgroup analysis to identify those who are likely to achieve undetectable MRD with 3 cycles of ibrutinib plus 12 cycles of combination therapy, according to Wierda.