FDA approves Bristol Myers Squibb's Zenbexus, first CELMoD drug for multiple myeloma

Aug 14, 2026

The FDA has granted accelerated approval to Bristol Myers Squibb's Zenbexus (iberdomide), marking the debut of the CELMoD class of protein degraders for multiple myeloma. Approved for second-line use alongside Darzalex and dexamethasone, Zenbexus is the first drug cleared using minimal residual disease (MRD) as a surrogate endpoint. In the Phase 3 Excaliber-RRMM trial, the Zenbexus combo achieved a 41% MRD-negative complete response rate versus 21% for the comparator. Priced at $29,500 per cycle, Zenbexus is expected to help BMS offset generic erosion of its blockbusters Revlimid and Pomalyst.

Zenbexus FDA accelerated approval

▪Zenbexus is approved for use in combination with Johnson & Johnson's Darzalex and dexamethasone in patients who have received at least one prior line of therapy.
▪The FDA granted accelerated approval to Bristol Myers Squibb's Zenbexus, also known as iberdomide, on August 13, 2026, for treating adults with relapsed or refractory multiple myeloma.

CELMoD protein degradation mechanism

▪Zenbexus carries a boxed warning on its label for embryo-fetal toxicity, serious venous and arterial thromboembolism, and cardiovascular complications.
▪CELMoD protein degraders bind to cereblon to leverage a cell's built-in disposal system, marking disease-driving proteins for destruction with tighter binding and more rapid degradation than legacy immunomodulatory drugs.
▪Zenbexus is the first FDA-approved cereblon-modulating (CELMoD) protein degrader, establishing a new class of medicines for multiple myeloma.

MRD-negative complete response endpoint

▪Zenbexus is the first new drug in multiple myeloma to win FDA accelerated approval driven directly by minimal residual disease (MRD) as a surrogate endpoint.
▪The FDA issued draft guidance in January 2026 regarding the potential use of MRD and complete response to support accelerated approvals in multiple myeloma.

Excaliber-RRMM phase 3 results

▪In the Phase 3 Excaliber-RRMM trial, 41% of patients in the Zenbexus combination cohort achieved an MRD-negative complete response compared to 21% in the comparator arm.
▪The Phase 3 Excaliber-RRMM trial evaluated 939 patients with relapsed or refractory multiple myeloma, comparing the Zenbexus combination against a regimen of Darzalex, Velcade, and dexamethasone.
▪In the Excaliber-RRMM trial, 7.8% of patients discontinued the Zenbexus combination due to adverse reactions, and ultimately fatal adverse reactions were reported in 10 patients.

Bristol Myers myeloma franchise

▪William Blair analyst Matt Phipps reported that Zenbexus has a list price of $29,500 per 28-day treatment cycle and forecasts annual U.S. sales will surpass $1 billion in 2031.
▪Bristol Myers Squibb is turning to its CELMoD franchise to offset declining revenues from its legacy blockbusters Revlimid and Pomalyst, which face generic competition.
▪Bristol Myers Squibb's second CELMoD drug, mezigdomide, is currently under FDA review for multiple myeloma with a regulatory decision expected by May 13, 2027.