Venetoclax plus rituximab induces durable responses among patients with relapsed/refractory chronic lymphocytic leukemia (CLL), according to an abstract presented at the XVII International Workshop on Chronic Lymphocytic Leukemia (iwCLL).1
Venetoclax is a BCL-2 inhibitor approved for the treatment of relapsed/refractory CLL. This ongoing phase 1b study is evaluating the combination of venetoclax and rituximab.
The study treated 49 patients with venetoclax plus rituximab until complete remission (CR) or minimal residual disease (MRD)-negativity was achieved, after which patients could discontinue venetoclax. Patients with progressive disease after discontinuation could reinitiate the combination. The patients had received a median of 2 prior regimens.
The overall response rate was 86%, with 51% achieving CR. MRD-negativity was observed in 28 patients (57%), which occurred within 7 months by 22 of the patients; the remaining patients experienced MRD-negativity between 12 and 22 months.
The progression-free survival was estimated to be 78.8% at 24 months, with a duration of response of 87.8%.
The study was discontinued by 20 (41%) of patients due to progressive disease (11), withdrawn consent (3), lost to follow-up (1), and adverse events (AEs) related (2) or not related to therapy (3).
Seventeen patients remain on study treatment, with a median duration of response of 27.9 months.
Venetoclax was discontinued by 17 patients as allowed by the protocol. In this subset, the median time on venetoclax was 16.3 months (range, 5-38). Of these patients, 12 remain in active follow-up and 4 discontinued without evidence of progression. Venetoclax was reinitiated by 2 patients to treat progressive disease.
According to investigators, this study demonstrates “that it is possible to discontinue venetoclax and maintain prolonged treatment-free remission.”
- Lash LL, Brander D, Anderson MA, et al. Durability of responses on continuous therapy and following drug cessation in deep responders with venetoclax and rituximab. Paper presented at: XVII International Workshop on Chronic Lymphocytic Leukemia; May 12-15, 2017; New York, NY.