FDA OKs Dostarlimab Plus Chemo for Endometrial Cancer

M. Alexander Otto, PA, MMS

July 31, 2023

The US Food and Drug Administration (FDA) has approved dostarlimab-gxly (Jemperli, GlaxoSmithKline) with carboplatin and paclitaxel, followed by single-agent dostarlimab, for primary advanced or recurrent endometrial cancer that is mismatch repair–deficient (dMMR), as determined by an FDA-approved test or microsatellite instability–high (MSI-H).

The approval was based on GSK's RUBY trial. Across 122 patients with dMMR/MSI-H primary advanced or recurrent endometrial cancer, progression-free survival was 30.3 months in women randomly assigned to dostarlimab on a background of carboplatin and paclitaxel, followed by dostarlimab monotherapy, vs 7.7 months among women randomly assigned to placebo (hazard ratio [HR], 0.29; P < .0001), according to the FDA's press release.

MMR/MSI tumor status was determined by local testing or by the Ventana MMR RxDx Panel when local testing was unavailable.

"Until now, chemotherapy alone has been the standard of care with many patients experiencing disease progression," GSK executive Hesham Abdullah said in the company's press release. The trial results "and today's approval underscore our belief in the potential for Jemperli to transform cancer treatment as a backbone immuno-oncology therapy."

Dostarlimab was already approved in the US as monotherapy for adults with dMMR recurrent or advanced endometrial cancer that has progressed on or following a platinum-containing chemotherapy and is not a candidate for curative surgery or radiation. The latest approval means that the agent "is now indicated earlier in treatment in combination with chemotherapy," GSK said.

Dostarlimab also carries an indication for dMMR recurrent or advanced solid tumors that have progressed on or following prior treatment when there are no satisfactory alternative treatment options.

Immune-mediated adverse reactions with dostarlimab include pneumonitis, colitis, hepatitis, endocrinopathies such as hypothyroidism, nephritis with renal dysfunction, and skin adverse reactions. The most common adverse reactions (≥ 20%) with carboplatin and paclitaxel in the Ruby trial were rash, diarrhea, hypothyroidism, and hypertension.

The recommended dostarlimab dose is 500 mg every 3 weeks for 6 doses with carboplatin and paclitaxel, followed by 1000 mg monotherapy every 6 weeks until disease progression or unacceptable toxicity, or up to 3 years.

Drugs.com lists dostarlimab's price at $11,712.66 for 500 mg/10 mL intravenous solution.

M. Alexander Otto is a physician assistant with a master's degree in medical science and a journalism degree from Newhouse. He is an award-winning medical journalist who worked for several major news outlets before joining Medscape. Alex is also an MIT Knight Science Journalism fellow. Email: aotto@mdedge.com.

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