GSK's cancer drug Jemperli (dostarlimab) hit its primary goal in a mid-stage trial for a specific type of locally advanced rectal cancer, with patients showing no detectable signs of cancer for a year or more. The targeted subtype involves tumors that can't properly repair DNA damage — making them highly responsive to immunotherapy. GSK plans to share the data with global regulators.
GSK's immunotherapy drug Jemperli (dostarlimab) has cleared a key milestone, meeting the primary endpoint of the phase II AZUR-1 trial in locally advanced rectal cancer. The trial focused on a genetically distinct subtype — tumors with deficient DNA mismatch repair (dMMR) — where mutations accumulate and make the cancer highly responsive to checkpoint inhibitors like Jemperli. A clinically significant proportion of patients showed no detectable cancer for one year or more after treatment.
This is meaningful because the current standard of care for these patients — chemotherapy, radiation, and surgery — often results in lifelong consequences like colostomy bag use and infertility. An effective immunotherapy-based alternative could dramatically improve quality of life for this patient population. The drug's safety and tolerability profile was also consistent with previous studies in solid tumors.
By the Numbers
Why it matters: If approved for rectal cancer, Jemperli could offer a surgery-sparing, life-changing option for tens of thousands of patients annually — while also strengthening GSK's oncology pipeline heading into the next decade.
