Real-world Treatment Durations of Venetoclax in CLL, SLL

Venetoclax is approved for the treatment of chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL) when combined with obinutuzumab as a first-line therapy or with rituximab in relapsed or refractory patients. Researchers, led by Anna Teschemaker, analyzed real-world data on treatment patterns in the United States for venetoclax plus obinutuzumab or rituximab. Their findings were presented at the European Hematology Association 2023 Hybrid Congress.

Based on retrospective cohort analysis, the researchers found median duration of treatment (DoT) was approximately 12 months for venetoclax plus obinutuzumab and 24 months for venetoclax plus rituximab, both of which were consistent with approved first-line and relapsed or refractory regimens. However, the authors noted a high number of patients did not maintain the fixed-dosing schedule.

Fixed Venetoclax Dosing Schedule May Hamper Treatment

The final analysis included 115 patients in the first-line venetoclax plus obinutuzumab group (mean age, 62.3 years; 73.3% male) and 133 in the relapsed or refractory venetoclax plus rituximab group (mean age, 64.2 years; 73.8% male). Authors noted 48.3% of relapsed or refractory patients had received prior targeted therapies.

The DoT was defined as the time from the start of the treatment regimen until either treatment discontinuation or end of follow-up. Investigators used Kaplan-Meier models to estimate the odds of remaining on treatment for both groups.

The venetoclax plus obinutuzumab group had a median follow-up of 11.4 months, a median DoT of 12.4 months (95% CI, 11.5-13.4), and a probability of remaining on treatment at month 12, 18, and 24 of 56.4%, 20.2%, and 5.1%, respectively. In 55 (47.8%) first-line patients with 12 or more months of follow-up, 9.1% had fixed-duration treatment cycles and 38.2% discontinued early, with a median DoT of 4.6 months.

Comparatively, the venetoclax plus rituximab group had a median follow-up of 15.5 months, a median DoT of 24.5 months (95% CI, 13.4-25.2), and a probability of remaining on treatment at month 24, 30, and 36 of 53.8%, 19.0%, and 19.0%, respectively. Among 39 (29.3%) relapsed or refractory patients with 24 or more months of follow-up, 5.1% had fixed cycles and 46.2% discontinued early, with a median DoT of 7.1 months.

Overall, the authors suggested “this study provides evidence that a [venetoclax]-based approach may not be suitable for all patients with CLL/SLL. Future studies should include additional follow-up with a larger sample, reasons for treatment discontinuation, and patient molecular genetic profile.”

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