Janux Therapeutics saw a steep stock decline after releasing an updated cut of early clinical data for its masked T‑cell engager JANX007 in metastatic castration-resistant prostate cancer. The company reported lower-than-expected response rates in the new data set, prompting investor concern despite the biotech characterizing the broader Phase 1 safety and activity profile as still encouraging. Analysts noted the market reaction may reflect high expectations for first-in-class T‑cell engagers and the sector’s sensitivity to early efficacy signals. Company communications emphasized ongoing dose escalation and further data maturation. The episode underscores how small, early clinical datasets can drive outsized valuation swings for immuno-oncology developers and how investor sentiment can diverge from clinical teams’ interpretation of evolving safety and efficacy signals.