The 3-year follow-up results from the CAPTIVATE trial, which evaluated the fixed-duration combination therapy of ibrutinib plus venetoclax in treatment-naive chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL), demonstrated significant and sustained survival outcomes, including in patients with high-risk disease. These findings will be presented at the 2022 ASCO Annual Meeting (Abstract 7519).
Bruton's tyrosine kinase (BTK) inhibitors, like ibrutinib, and B-cell lymphoma 2 (BCL2) inhibitors, such as venetoclax, have revolutionized CLL treatment. However, long-term therapies until disease progression are costly and pose risks of toxicity and resistance. Targeting both BTK and BCL2 simultaneously may result in deeper remissions, allow for off-treatment periods, and help prevent resistance. The CAPTIVATE study is testing this hypothesis.”
A Powerful New Combination
BTK and BCL2 inhibitors have significantly transformed first-line CLL treatment by providing daily oral therapy, eliminating the need for ongoing systemic chemoimmunotherapy. However, more research is required to fully understand the long-term survival benefits and potential risks of doublet therapy regimens. This research could inform future treatment decisions.
The multicenter, phase 2, randomized CAPTIVATE trial was designed to investigate both minimal residual disease (MRD)–guided treatment discontinuation and fixed-duration therapy in untreated CLL or SLL patients, who were randomly assigned to receive either the ibrutinib/venetoclax combination therapy or a placebo.
Preclinical and clinical data have shown synergistic effects of the ibrutinib/venetoclax combination, with the potential to achieve undetectable MRD. However, the optimal duration of therapy—whether fixed-duration or MRD-guided—remains uncertain. The CAPTIVATE study, which explores both strategies, is expected to influence clinical practice and shape future trials.
Earlier analyses in the MRD cohort of the CAPTIVATE trial showed that nearly two-thirds of patients had undetectable MRD in either bone marrow or peripheral blood after completing 12 cycles of the combination therapy. Primary analyses of the fixed-duration cohort showed promising outcomes, with 55% of patients achieving a complete response.
3-Year Findings: Durable Remission
The current analysis, focusing on 3-year outcomes in the fixed-duration therapy cohort (159 patients), provides further evidence of the potential for durable remission. Results indicate that the combination therapy of ibrutinib and venetoclax yields deep and lasting responses.
Among the 57% of patients who achieved complete response (an increase from 55% in the primary analysis), 93% maintained their response for at least 12 months after treatment. Additionally, 78% of patients had undetectable MRD 1 year after completing therapy. By 3 years post-treatment, progression-free survival (PFS) was 88%, and overall survival (OS) was 98%.
Notably, 17% of patients in the cohort (27 patients) had TP53 aberrations (deletions or mutations in chromosome 17p), which are associated with poorer prognosis. Among this subgroup, PFS was 80%. In the 89 patients with unmutated immunoglobulin heavy chain genes—a factor linked to worse survival outcomes—PFS was 86%. These findings demonstrate that the fixed-duration ibrutinib/venetoclax combination is effective even in high-risk patients.
“These results reflect excellent disease control,” said Dr. Barr. “We anticipate that CAPTIVATE and other studies involving BTK/BCL2 combinations will reshape treatment strategies, making it essential for clinicians to stay informed about these efficacy and safety outcomes to better guide CLL patients.”
Maximizing Patient Benefit
In addition to strong survival outcomes, the ibrutinib/venetoclax combination offers an oral, chemotherapy-free treatment, reducing the burden on patients. Patients prefer avoiding infusion centers. In the COVID-19 era, using fixed-duration regimens could also enhance vaccine responses and protect against infections, including COVID-19.
Fixed-duration therapy has an advantage over continuous therapy because it reduces long-term treatment exposure, which could help lower the risks of treatment-related toxicity and resistance. However, the comparative efficacy and safety of fixed-duration regimens versus chemoimmunotherapy, as well as the potential benefits of doublet versus triplet combinations, remain areas of active investigation.