Venetoclax and ibrutinib have “clinically complimentary activity” that provided a rationale for combining the two, Dr. Wierda said at ASCO. Ibrutinib is a BTK inhibitor that has a high rate of response and durable disease control, though continuous treatment is indicated, he said, because most patients achieve partial remissions as best response and continue to have residual disease in blood or bone marrow. Venetoclax, he added, is a BCL-2 inhibitor that produces durable partial remissions, though “residual disease is typically present in the form of persistently enlarged lymph nodes,” he said. “Venetoclax is highly effective at clearing disease from blood and bone marrow.”
The phase 2 CAPTIVATE trial includes a total of 164 patients younger than 70 years of age who receive a 3-cycle ibrutinib lead-in, followed by ibrutinib plus venetoclax for 12 cycles. At that point, patients are randomized according to MRD status. Patients with confirmed undetectable MRD are randomized to further treatment with ibrutinib or placebo, and those with undetectable MRD not confirmed are randomized to ibrutinib versus ibrutinib plus venetoclax.
In addition to early efficacy data, Dr. Wierda also reported some safety data. Compared with the single-agent ibrutinib lead-in period, combined ibrutinib plus venetoclax treatment had more gastrointestinal-associated events and neutropenia. Almost half of patients (45%) have had a treatment-related grade 3-4 adverse event, though just 18 (11%) have had treatment-related adverse events classified as serious, and there have been no adverse event-related deaths on study.
The high activity of ibrutinib plus venetoclax in CAPTIVATE supports further study of the combination, Dr. Wierda said. A randomized, open-label phase 3 trial of ibrutinib plus venetoclax versus chlorambucil plus obinutuzumab as first-line treatment for CLL is currently recruiting.
The study was sponsored by Pharmacyclics, an AbbVie company. Dr. Wierda reported consulting and research funding from Pharmacyclics, AbbVie, and several other companies.
SOURCE: Wierda WG et al. ASCO 2018, Abstract 7502.