Partner Therapeutics’ Bizengri (bispecific antibody targeting NRG1 fusions) received FDA approval for advanced cholangiocarcinoma driven by NRG1 gene fusions. The approval makes Bizengri the first FDA-approved therapy for this ultra-rare molecular subset, moving a previously hard-to-treat population toward a targeted option. Partner Therapeutics acquired U.S. rights to the program from Merus in 2024, positioning the company to commercialize in the U.S. market and potentially expand evidence generation around fusion-positive disease. The decision narrows the therapeutic focus to a specific biomarker-defined oncology niche. For biotech investors and pipeline teams, the event underscores continued regulatory support for biomarker-stratified drug development in oncology, where small patient populations can still be supported by clear molecular selection.