Bristol Myers drug shows survival benefit in breast cancer trial
Iza-bren becomes first bispecific ADC to achieve dual primary endpoints in Phase 3 triple-negative breast cancer study
Bristol Myers Squibb's experimental cancer drug izalontamab brengitecan achieved statistically significant improvements in both progression-free and overall survival in a Phase 3 trial for advanced triple-negative breast cancer, marking a potential breakthrough for a disease with limited treatment options.
The interim analysis of the China-based BL-B01D1-307 study, which enrolled 418 patients whose disease had progressed after prior taxane therapy, showed that the bispecific antibody-drug conjugate met both primary endpoints. According to Bristol Myers, these topline results represent the first time a bispecific antibody-drug conjugate has demonstrated dual benefits in both progression-free and overall survival in a Phase 3 trial for triple-negative breast cancer.
Despite the positive clinical news, Bristol Myers shares declined 0.5% to $61.01 in Thursday trading, giving the pharmaceutical giant a market capitalization of $125.4 billion. The company's growth portfolio, which includes newer oncology drugs, climbed 23% in 2025 to $16.3 billion, now accounting for more than half of total revenue.
Triple-negative breast cancer, which accounts for approximately 15% of all breast cancers, is an aggressive form of the disease that lacks receptors for estrogen, progesterone, and HER2, making it unresponsive to targeted therapies that work for other breast cancer subtypes. Patients with advanced or metastatic disease face poor outcomes, with median survival typically measured in months.
Izalontamab brengitecan, developed in partnership with SystImmune, targets both epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 3 (HER3) while delivering a topoisomerase I inhibitor payload. The drug has received Breakthrough Therapy Designation from the US Food and Drug Administration for previously treated advanced EGFR-mutated non-small cell lung cancer, as well as Breakthrough Therapy Designation from China's National Medical Products Administration for seven indications.
The Phase 3 success represents the third trial in which izalontamab brengitecan has achieved its primary endpoints, strengthening the drug's profile as Bristol Myers seeks to replenish its oncology pipeline amid a significant patent cliff. The company faces declining sales from its blockbuster blood cancer drug Revlimid, with revenue from legacy products expected to fall 18-20% in 2025 due to generic competition.
Bristol Myers licensed izalontamab brengitecan from SystImmune in 2023 for development outside China, part of a broader strategy to secure external innovation as internal research faces patent expirations. The company anticipates six pivotal readouts in 2026 across neurology, cardiovascular disease, immunology, and oncology, as it aims to launch 10 new drugs with 30 label expansions over the next five years.
"The dual survival benefit demonstrated in this Phase 3 study is particularly meaningful for patients with triple-negative breast cancer who have exhausted standard treatment options," said Adam Friedman, an analyst at Piper Sandler. "If these results hold in broader patient populations, izalontamab brengitecan could become a cornerstone of Bristol Myers' oncology portfolio and help offset revenue losses from Revlimid generics."
Full data from the interim analysis are expected to be presented at an upcoming medical conference, with primary completion and data collection for the trial anticipated in June 2026. Bristol Myers did not disclose the magnitude of the survival benefit or specify the chemotherapy comparator used in the study.
The company currently trades at 17.8 times trailing earnings but just 7.6 times forward earnings, reflecting investor concerns about the patent cliff. Analysts have an average price target of $61.71 on the stock, with six rating it a buy, 17 a hold, and one a sell, according to market data.