Bristol Myers, SystImmune breast cancer drug cuts progression risk in study

Oct 23 — Bristol Myers Squibb and partner SystImmune said on Friday their experimental ​breast cancer treatment slowed disease progression compared to standard chemotherapy in a late-stage study.

The drug, izalontamab brengitecan, reduced the ‌risk of disease worsening or death by 59% in patients with advanced hormone-receptor-positive, HER2-negative ⁠breast cancer — the most common ​form of breast cancer — who ⁠had failed at least one prior line of chemotherapy.

Izalontamab brengitecan ‌belongs to a class ‌of treatments known as antibody-drug conjugates, often called "guided missiles". ⁠It targets two specific proteins, EGFR ⁠and HER3, to deliver a cancer-killing payload directly to tumor cells.

In the study, which enrolled 383 patients, those treated with the drug lived for a median of 8.2 months without their cancer growing, compared to four months for the participants ‌on standard chemotherapy.

About 40.5% of patients on ​iza-bren saw their tumors shrink, compared to 20.2% on chemotherapy. The response lasted a median of 6.9 months, versus 4.2 months for chemotherapy.

Data on overall survival, how long patients lived in total, was not yet mature at the time of the interim analysis. The full results will be presented at the ​European Society for Medical Oncology congress in Madrid.

Bristol Myers had partnered ‌with SystImmune, a ‌unit of ⁠Chinese drugmaker Sichuan Biokin Pharmaceutical, in an up to $8.4 billion deal announced in 2023 to develop and commercialize the drug outside mainland China.

Its side effects were manageable and no new safety concerns ‌emerged, Bristol Myers said. ​Only 1.6% of patients stopped treatment ‌because of side effects, ⁠while two ​patients developed mild-to-moderate lung inflammation.

(Reporting by Kamal Choudhury in Bengaluru; Editing by ​Shilpi Majumdar)

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