When first-line chemotherapy fails patients, there is no accepted standard of care. In the phase-2 KEYNOTE-180 study, pembrolizumab, a monoclonal anti-PD-1 antibody, provided durable responses in patients with esophageal cancer that had progressed after two or more prior therapies.
Dr. Toshihiko Doi of National Cancer Center Hospital East, in Kashiwa, Japan, and colleagues in the open-label, randomized, phase-3 KEYNOTE-181 study evaluated the outcomes of treatment with pembrolizumab versus the investigator's choice of paclitaxel, docetaxel, or irinotecan in patients with advanced or metastatic esophageal cancer who had progressed after one line of prior therapy.
Among the 628 patients included in the study, expression of PD-L1 scores of at least 10 was similar in the pembrolizumab group (107/314, 34%) and in the chemotherapy group (115/314, 37%).
At the final analysis, median overall survival of patients with PD-L1 scores of at least 10 was significantly longer in the pembrolizumab group (9.3 months) than in the chemotherapy group (6.7 months), the researchers report in the Journal of Clinical Oncology.
The 12-month survival rate was 43.0% in the pembrolizumab group and 20.4% in the chemotherapy group.
In the analysis of all patients (regardless of PD-L1 score), median overall survival did not differ significantly between the pembrolizumab and chemotherapy groups (7.1 months in both groups). And in subgroup analyses, median overall survival did not differ between groups in patients with squamous-cell carcinoma (8.2 months vs. 7.1 months, respectively).
Among patients with PD-L1 scores of at least 10, median progression-free survival was nominally lower in the pembrolizumab group, but tumor response rates were higher, compared with the chemotherapy group.
Treatment-related adverse event rates were lower in the pembrolizumab group (64%) than in the chemotherapy group (86%), but immune-mediated adverse events and infusion reactions were more common with pembrolizumab (23.2% vs. 7.4%).
"These data contributed to the current US Food and Drug Administration approval of pembrolizumab for patients with metastatic or locally advanced, esophageal squamous cell carcinoma with PD-L1 scores of 10 or higher in the second-line setting," the authors conclude.
Dr. Doi did not respond to a request for comments.
Merck Sharpe and Dohme funded the study, employed three of the authors and had various relationships with many others.
By Reuters Staff
SOURCE: https://bit.ly/2SNyIyO Journal of Clinical Oncology, online October 7, 2020.
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