The U.S. Food and Drug Administration has granted accelerated approval to Bristol Myers Squibb’s ZENBEXUS™ (iberdomide), marking the first FDA approval for a therapy from the company’s new CELMoD class and opening another treatment option for previously treated multiple myeloma.
The FDA approved iberdomide on August 13, 2026, in combination with daratumumab and hyaluronidase-fihj plus dexamethasone for adults with multiple myeloma who have received at least one previous line of therapy containing both a proteasome inhibitor and an immunomodulatory agent.
ZENBEXUS is the first FDA-approved CELMoD, or cereblon E3 ligase modulator, representing a new generation of targeted protein-degradation medicines developed from the scientific foundation established by earlier immunomodulatory drugs.
The approval therefore carries importance beyond a single multiple myeloma product.
It provides the first regulatory validation of Bristol Myers Squibb’s CELMoD platform.
Iberdomide binds to cereblon, a component of an E3 ubiquitin ligase complex, and promotes degradation of proteins involved in the survival of myeloma cells. The approach builds on the biological mechanisms used by established immunomodulatory agents while aiming to provide stronger and more selective protein degradation.
The FDA’s accelerated approval was based on the Phase 3 EXCALIBER-RRMM trial.
The study compared iberdomide plus daratumumab and hyaluronidase-fihj and dexamethasone with daratumumab, bortezomib and dexamethasone in patients with relapsed or refractory multiple myeloma.
In the primary efficacy population, 41% of patients receiving the iberdomide regimen achieved minimal residual disease-negative complete response, compared with 21% in the control group. The difference was statistically significant.
Minimal residual disease, or MRD, refers to very small numbers of cancer cells that remain after treatment and may not be detectable using conventional clinical assessments.
Achieving MRD negativity is regarded as a marker of particularly deep response in multiple myeloma and has become increasingly important in clinical development.
The regulatory decision is especially notable because it represents the first FDA approval in relapsed or refractory multiple myeloma based on MRD-negative complete response.
However, the distinction between accelerated and full approval is important.
ZENBEXUS has not yet received conventional full approval for the indication.
Its continued authorization may depend on verification of clinical benefit through ongoing confirmatory evidence. EXCALIBER-RRMM continues to evaluate progression-free survival, another of the study’s dual primary endpoints.
This means Bristol Myers Squibb has achieved an important regulatory milestone before the complete progression-free survival dataset has matured.
For patients and the company, the advantage is earlier access to a potentially meaningful new therapy.
For regulators, the trade-off is that longer-term clinical benefit still needs to be confirmed.
Safety will also be an important part of ZENBEXUS use.
The prescribing information carries boxed warnings for embryo-fetal toxicity and serious venous and arterial thromboembolism. Additional warnings include neutropenia, infections and secondary primary malignancies.
Because of embryo-fetal risk, ZENBEXUS is available only through a restricted Risk Evaluation and Mitigation Strategy, or REMS, distribution program.
In the EXCALIBER-RRMM program, neutropenia and infections were common among patients receiving the ZENBEXUS combination, making monitoring and supportive care important components of treatment.
Commercially, the launch gives Bristol Myers Squibb a potential successor platform in a market where the company has long played a major role through immunomodulatory drugs.
Multiple myeloma treatment has evolved rapidly over the past decade.
Anti-CD38 antibodies, proteasome inhibitors, immunomodulatory drugs, CAR-T therapies and bispecific antibodies have substantially expanded treatment options.
That success has also created a more complex competitive environment.
Patients increasingly move through several drug classes over the course of their disease, making medicines that can remain effective after prior therapy especially valuable.
ZENBEXUS has been approved as early as the first relapse, giving Bristol Myers Squibb an opportunity to position CELMoD therapy relatively early in the treatment sequence rather than limiting it to heavily pretreated disease.
Reuters reported that Bristol Myers Squibb has set a U.S. list price of approximately $29,500 for a 28-day cycle, with commercial availability expected within weeks of the approval.
The company is also developing another CELMoD, mezigdomide, reinforcing the view that ZENBEXUS is intended to establish a broader therapeutic platform rather than function as a stand-alone product. Bristol Myers Squibb said mezigdomide is also under FDA review in another multiple myeloma regimen.
This pipeline matters strategically.
The pharmaceutical industry has invested heavily in targeted protein degradation because it offers a way to remove disease-driving proteins rather than simply blocking their activity.
CELMoDs represent one implementation of that broader concept.
ZENBEXUS now provides one of the clearest examples of targeted protein degradation moving from research strategy into routine commercial medicine.
The approval also demonstrates how regulatory endpoints in oncology are evolving.
Traditional cancer approvals often focus on progression-free survival or overall survival. Using MRD-negative complete response as the basis for accelerated approval allows regulators to act on an earlier biomarker of treatment depth while waiting for mature long-term outcomes.
That approach could influence future multiple myeloma development programs if confirmatory data ultimately validate the clinical benefit.
For Bristol Myers Squibb, the next major question is therefore no longer whether CELMoD technology can reach the market.
It has.
The more important issues will be how ZENBEXUS performs against an increasingly crowded range of myeloma therapies, how widely physicians use the regimen after first relapse and whether ongoing progression-free survival data support conversion to full approval.
The August 13 decision marks both a new multiple myeloma treatment and the commercial arrival of an entirely new Bristol Myers Squibb drug class.
