Sanofi abruptly stopped development of a key early-stage immunology degrader program with Nurix, ending work on SAR448272 (NX-3911), a STAT6 degrader in a Phase I study. Nurix said the collaboration remains in place for other targets and programs, but investors punished the news, sending the stock down sharply. The termination also interrupts an ongoing European Phase I effort that had begun recruitment in Germany and planned broader expansion across additional countries. The halted program had been positioned within a multi-year protein degradation collaboration between the two companies. For the sector, the move underscores how early clinical readouts and evolving risk assessments can quickly reshape platform portfolios—even when overall cash runway and other clinical assets remain unchanged.