FDA Approves First Companion Diagnostic for Dostarlimab-gxly in dMMR Solid Tumors

The FDA has approved the VENTANA MMR RxDx Panel, which marks the first approval of a companion diagnostic that can help in identifying patients with DNA mismatch repair–deficient (dMMR) solid tumors who may be eligible for treatment with single-agent dostarlimab-gxly (Jemperli), according to a press release from assay’s developer Roche.¹

The approval notably provides access to a fully automated panel of MMR biomarkers that are tested via immunohistochemistry. This allows for informed and impactful treatment decisions for patients with dMMR solid tumors.

“As the first companion diagnostic of its kind, this test can help qualify patients with solid tumours that are deficient in MMR who have progressed in their disease and who have no other suitable treatment options,” Thomas Schinecker, chief executive officer at Roche Diagnostics, said in a press release. “Based on the results of our MMR biomarker test, these patients may be eligible to receive GSK’s Jemperli. We are pleased that our innovative companion diagnostic label continues to grow to serve more patients.”

The VENTANA MMR RxDx Panel assesses the expression of MMR proteins with formalin-fixed, paraffin-embedded tumor tissue that has been stained with OptiView DAB immunohistochemistry Detection Kit and ancillary reagents.

Dostarlimab recently received expanded approval by the FDA for the treatment of dMMR solid tumors in August 2021 following an accelerated approval for dMMR endometrial cancer granted in April 2021.^2,3 The approval was based on the results of the phase 1 GARNET trial (NCT02715284) in which the agent demonstrated an objective response rate of 41.6% (95% CI, 34.9%-48.6%), which included a complete response rate of 9.1% and a partial response rate of 32.5%. Among patients with non-endometrial tumors (n = 106), the ORR was 38.7% (95% CI, 29.4%-48.6%).

Additional findings indicated that the overall study population (n = 209) experienced a median duration of response of 34.7 months (range, 2.6-35.8+), with a 6-month maintained response rate of 95.4%.

“Dostarlimab is an important new treatment option for patients with mismatch repair-deficient recurrent or advanced solid cancers who have progressed and have no alternative options. As we saw in the GARNET trial, of those patients who respond to treatment with dostarlimab, nearly all continued to respond for six months or longer,” Jubilee Brown, MD, professor and Division Director of Gynecologic Oncology at Atrium Health, Levine Cancer Institute, noted in a press release.

References

1. Roche receives FDA approval for first companion diagnostic to identify dMMR solid tumour patients eligible for anti-PD-1 immunotherapy. News release. Roche. August 18, 2021. Accessed August 19, 2021. https://bit.ly/3mhONwG
2. GSK receives FDA accelerated approval for JEMPERLI (dostarlimab-gxly) for adult patients with mismatch repair-deficient (dMMR) recurrent or advanced solid tumours. GlaxoSmithKline. News release. August 17, 2021. Accessed August 17, 2021. https://bit.ly/3iQxHnj
3. FDA Approves Immunotherapy for Endometrial Cancer with Specific Biomarker. News release. FDA. April 21, 2021. Accessed April 22, 2021. https://bit.ly/3yWzYTD