FDA OKs New Frontline Endometrial Cancer Regimen, First in Decades

The FDA approved the immune checkpoint inhibitor dostarlimab (Jemperli) plus chemotherapy as a frontline option for certain patients with advanced or recurrent endometrial cancer, the agency announced on Monday.

For adults with primary advanced or recurrent endometrial cancer that is mismatch repair-deficient (dMMR) or microsatellite instability-high (MSI-H), dostarlimab is now approved as part of a combination regimen with carboplatin and paclitaxel, followed by single-agent use of the PD-1 inhibitor.

Dostarlimab’s approval represents “the first new frontline treatment option in decades” for patients with endometrial cancer, drugmaker GSK said in a press release.

Approval was based on interim results from the phase III RUBY trial, which showed that adding dostarlimab to frontline chemotherapy in the dMMR/MSI-H population reduced the risk for disease progression or death by 71% versus chemotherapy alone (HR 0.29, 95% CI 0.17-0.50, P<0.001).

“As a clinician, I celebrate the practice-changing potential of adding Jemperli to chemotherapy for patients with dMMR/MSI-H primary advanced or recurrent endometrial cancer who have had limited treatment options,” said principle investigator Matthew Powell, MD, of the Washington University School of Medicine in St. Louis, in a statement. “Based on the results from the RUBY clinical trial, I look forward to the addition of Jemperli to chemotherapy becoming a new standard of care for patients.”

RUBY randomized 494 patients with primary advanced or recurrent stage III/IV endometrial cancer not amenable to curative therapy. Participants were randomly assigned 1:1 to receive dostarlimab 500 mg or placebo plus carboplatin and paclitaxel every 3 weeks, followed by dostarlimab 1,000 mg or placebo every 6 weeks for up to 3 years.

Of these, 122 patients had dMMR/MSI-high disease, a group that formed the basis for the current approval. Median progression-free survival (PFS) in this subgroup reached 30.3 months in the dostarlimab arm versus 7.7 months in the placebo arm. Overall survival data continue to be assessed, noted GSK. According to findings in the dMMR/MSI-high subgroup published in the New England Journal of Medicine, 83.3% of patients in the dostarlimab arm were alive at 24 months compared with 58.7% of those in the placebo arm.

According to the drug labeling, treatment-emergent adverse events (AEs) occurring in 20% or more patients receiving dostarlimab included rash, diarrhea, hypothyroidism, and hypertension. Immune-mediated AEs in dostarlimab-treated patients included pneumonitis, colitis, hepatitis, endocrinopathies, nephritis with renal dysfunction, and skin adverse reactions.

Dostarlimab was previously approved as monotherapy for patients with dMMR recurrent or advanced endometrial cancer that has progressed on or following a prior platinum-containing regimen in any setting and who are not candidates for curative surgery or radiation.