The invited discussant of the GARNET study, John C. Krauss, MD, Medical Oncology Director of the Multidisciplinary Colorectal Cancer Clinic, Rogel Cancer Center of the University of Michigan, Ann Arbor, observed that “impressive” response rates to dostarlimab were demonstrated in a “relatively large number” of patients with mismatch repair–deficient (dMMR) disease, including 40% with colorectal cancer and 40% with other gastrointestinal tumors.1
“The majority of patients achieved some type of response, even if they didn’t meet the Response Evaluation Criteria in Solid Tumors, and the majority of those responses were long-lived,” he noted. “There are some responses ongoing for more than 2 years in this trial.”
Dr. Krauss further noted the relatively easy dosing schedule for the drug; however, he pointed out that pembrolizumab is now approved for every-6-week dosing, so dosing has become easier for that PD-1 inhibitor as well. Toxicity and also efficacy with dostarlimab appear to be in line with those of other anti–PD-1/PD-L1 inhibitors approved in the United States, he observed.
John C. Krauss, MD
Dr. Krauss looks forward to seeing data from further testing, including the evaluation of 14 different primary outcome measures in a phase IIb trial of more than 700 patients. However, he predicted the current phase I data from this large trial could be enough to gain approval.
“Immunotherapy with single-agent PD-1 inhibitors is safe and offers long-term disease control for a substantial number of patients,” Dr. Krauss commented. However, with efficacy so far limited to the 5% or so of patients with dMMR tumors, the question remains: “How can we get more patients with gastrointestinal cancer invited to the immunotherapy party?”
DISCLOSURE: Dr. Krauss has received research funding from Cardiff Oncology; has received institutional research funding from AbbVie, ACCRU, Amgen, AstraZeneca/MedImmune, Boehringer Ingelheim, Boston Biomedical, Hutchison MediPharma, Ignyta, Isofol Medical, Novartis, NSABP Foundation, and Tempest Therapeutics.
1. André T, Berton D, Curigliano G, et al: Safety and efficacy of anti–PD-1 antibody dostarlimab in patients with mismatch repair-deficient solid cancers: Results from GARNET study. 2021 Gastrointestinal Cancers Symposium. Abstract 9. Presented January 16, 2021.