Durable Responses and Optimized Dosing Shine in Nurix’s Bexobrutideg Data for Relapsed CLL

Efficacy: 83% Response Rate and Over 22 Months Median PFS

Nurix Therapeutics has unveiled updated Phase 1 data at the ASH Annual Meeting showing that bexobrutideg (NX-5948), an investigational BTK degrader, delivers promising efficacy for patients with relapsed or refractory chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL)—diseases where treatment options can be limited. Across 47 evaluable Phase 1a patients, the objective response rate (ORR) was 83%, with a median progression-free survival (PFS) of 22.1 months and a median duration of response (DOR) of 20.1 months. Notably, deepening of responses led to two complete remissions, an improvement over prior results as more patients reached longer-term follow-up.

Higher Dose Yields Stronger Responses in Randomized Comparison

Data from the randomized Phase 1b cohort comparing 200 mg versus 600 mg daily doses provide further insight: among 37 efficacy-evaluable patients, the 600 mg group achieved an ORR of 83.3%, notably higher than the 73.7% seen with 200 mg. The higher dose also trended towards longer progression-free survival, strengthening the rationale for advancing 600 mg as the recommended phase 2 dose.

Safety Remains Consistent and Favorable at Higher Dose

Bexobrutideg’s safety profile remained favorable even at the 600 mg recommended dose. Across all 126 patients in Phase 1a/1b, the most common treatment-emergent adverse events included mild bruising and neutropenia. No dose-limiting toxicities, systemic fungal infections, or Grade 4 infections occurred. Only one new atrial fibrillation event was observed, consistent with expected rates for the study population’s age group.

Robust Activity Across Difficult Patient Subsets

The trial population included heavily pretreated patients: the median number of prior therapies was three, with many having failed BTK and BCL-2 inhibitors and possessing high-risk mutations (e.g., TP53, BTK, and PLCG2). Even within these challenging groups, bexobrutideg achieved robust response rates and reductions in lymph node burden, independent of baseline mutation status.

Clinical Program Advancing: Pivotal Trial Now Enrolling

Encouraged by these results, Nurix is advancing the pivotal DAYBreak-CLL-201 Phase 2 trial with the 600 mg dose and continues global enrollment. The ongoing results not only reinforce bexobrutideg’s promise in CLL/SLL but may position it as a best-in-class therapy for patients who have exhausted existing treatment options. Investors and clinicians can tune into Nurix’s webcast on December 8, 2025, for deeper insights.

Key Takeaway: Dose Selection and Durability Set the Stage for Bexobrutideg’s Next Chapter

For investors and the medical community, the clear signals are hard to ignore: bexobrutideg’s 600 mg dose achieves a strong balance of efficacy and safety, particularly in difficult-to-treat CLL patients. With a new pivotal trial now open and a durable response profile, Nurix’s latest update marks a potentially important step for targeted therapies in blood cancers. Readers may want to monitor results from the upcoming DAYBreak program for further clinical validation and potential market impact.

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