Bristol Myers drug halves risk of myeloma progression in pivotal trial

Bristol Myers Squibb (NYSE:BMY) announced positive late-breaking results from its Phase 3 SUCCESSOR-2 clinical trial, demonstrating that its experimental oral therapy mezigdomide significantly extends the time patients with relapsed or refractory multiple myeloma live without their disease worsening.

The data, presented today in a late-breaking oral session at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting and simultaneously published in Annals of Oncology, represent the first Phase 3 results for mezigdomide.

The drug belongs to a novel class of therapies known as cereblon E3 ligase modulators, or CELMoDs, which are designed to optimize cancer cell destruction and immune system activation.

In the trial, a three-drug regimen combining oral mezigdomide with carfilzomib and dexamethasone extended median progression-free survival to 18 months, compared to 8.3 months for patients receiving carfilzomib and dexamethasone alone.

The findings represent a 52% reduction in the risk of disease progression or death, achieving a statistically significant result with a p-value less than 0.0001.

The therapeutic benefit remained consistent across multiple patient subgroups, including those receiving the regimen as a second- or third-line option and individuals presenting with higher-risk disease.

Secondary endpoints also favored the mezigdomide triplet regimen.

The overall response rate reached 80.2% in the mezigdomide cohort compared to 53.4% in the control arm, while the rate of patients achieving a complete response or better nearly tripled to 26.7% from 8.9%.

Median overall survival data remained immature at the time of analysis as the majority of patients continued to survive.

The improved clinical efficacy was accompanied by an increase in severe side effects, a common trade-off in aggressive oncology combinations.

Grade 3 to 4 treatment-emergent adverse events were reported in 83.7% of patients in the mezigdomide group compared to 56.5% in the control arm.

Severe neutropenia, a drop in white blood cell counts, occurred in 61.1% of patients receiving the triplet regimen versus 9.1% in the doublet group, while the incidence of severe infections stood at 34% compared to 15.6% in the control group.

Bristol Myers Squibb indicated that the overall safety profile was manageable and consistent with previous observations of the drug combination.