Nurix Therapeutics Presents Phase 1 Data for BTK Degrader Bexobrutideg in Chronic Spontaneous Urticaria

Nurix Therapeutics has disclosed Phase 1 translational and preclinical data for bexobrutideg (NX-5948) in chronic spontaneous urticaria, with findings that carry direct implications for formulation scientists and clinical manufacturing teams preparing for broader inflammation and immunology development. The data were presented at the 2026 Society for Investigative Dermatology Annual Meeting in Chicago, May 13–16.

Bexobrutideg is an orally bioavailable BTK degrader that recruits the cereblon E3 ligase complex to mark BTK for proteasomal elimination, removing both the kinase-dependent and scaffolding functions of the protein. In preclinical assays across primary human B cells, basophils, and mast cells, the compound demonstrated selective BTK degradation confirmed by global proteomic analysis of more than 8,700 proteins. Against remibrutinib, a BTK inhibitor, bexobrutideg showed approximately 25-fold greater potency in suppressing FcεRI-driven mast cell and basophil degranulation, the central pathogenic mechanism in CSU.

The Phase 1 healthy-volunteer data are particularly relevant to process and formulation teams: both single- and multiple-ascending-dose oral administration of a new tablet formulation produced rapid and robust BTK degradation in blood and skin compartments. Achieving tissue-level target engagement in skin using an oral tablet is a meaningful pharmacokinetic benchmark for a targeted protein degradation molecule, and the company has indicated this formulation will advance into inflammation and immunology indications. Manufacturing teams supporting scale-up should note that the cereblon E3 ligase recruitment mechanism places bexobrutideg within the PROTAC-adjacent degrader class, which carries distinct stability, solubility, and process validation considerations relative to conventional small molecules.

For regulatory affairs leads, the translational package presented at SID 2026 establishes the mechanistic rationale linking preclinical selectivity data to early clinical observations, a documentation pathway consistent with ICH Q8 quality-by-design principles as the program moves toward pivotal-stage filings. The breadth of the proteomic selectivity dataset, spanning more than 8,700 proteins, is likely to feature prominently in future IND amendments and investigator brochure updates as the CSU indication is pursued.

Nurix retains full ownership of bexobrutideg, and the Phase 1 dataset now supports expansion into additional inflammation and immunology indications beyond the hematologic oncology programs already in the clinic.

The measurable outcome to track is tissue BTK degradation depth in the forthcoming CSU efficacy cohorts, where the healthy-volunteer skin data will serve as the translational benchmark against which patient-level pharmacodynamic readouts are assessed.

Source: Nurix Therapeutics via GlobeNewswire, May 14, 2026.