August 2023: Dostarlimab-gxly (Jemperli, GlaxoSmithKline), followed by dostarlimab-gxly as a single agent, was approved by the Food and Drug Administration for the treatment of primary advanced or recurrent endometrial cancer (EC) that is mismatch repair deficient (dMMR), as determined by an FDA-approved test, or microsatellite instability-high (MSI-H).
RUBY (NCT03981796), a randomised, multicenter, double-blind, placebo-controlled trial, assessed efficacy. A predetermined subgroup of 122 patients with primary advanced or recurrent dMMR/MSI-H EC underwent an assessment of efficacy. When local data were not available, central testing (IHC) utilising the Ventana MMR RxDx Panel was used to assess the MMR/MSI tumour status.
Patients were randomly assigned (1:1) to receive either placebo with carboplatin and paclitaxel, followed by placebo, or dostarlimab-gxly with carboplatin and paclitaxel, followed by dostarlimab-gxly. The aforementioned link provides detailed prescribing information on several chemotherapy regimens. MMR/MSI status, past external pelvic irradiation, and disease stage (recurrent, primary Stage III, or primary Stage IV) were all taken into account when stratifying the randomization process.
Investigator-assessed progression-free survival (PFS) using RECIST v. 1.1 was the main efficacy outcome measure. With a median PFS of 30.3 versus 7.7 months (Hazard Ratio=0.29 [95% CI: 0.17, 0.50]; p-value0.0001) for the dostarlimab-gxly and placebo-containing regimens, respectively, a statistically significant PFS improvement was seen in the dMMR/MSI-H group.
Pneumonitis, colitis, hepatitis, endocrinopathies such as hypothyroidism, nephritis with renal failure, and skin adverse responses are examples of immune-mediated adverse reactions that can occur with dostarlimab-gxly. Rash, diarrhoea, hypothyroidism, and hypertension were the most frequent adverse events (20%) with dostarlimab-gxly in combination with carboplatin and paclitaxel. For a complete list of side effects, refer to the prescribed information.
Dostarlimab-gxly is to be administered at a dose of 500 mg every three weeks for six doses with carboplatin and paclitaxel, then 1,000 mg once every six weeks until the illness progresses or there is intolerable toxicity, which might take up to three years. When given on the same day as chemotherapy, dostarlimab-gxly should be given first.