NEW YORK – In Merck's Phase III Keynote-091 trial, adjuvant treatment with pembrolizumab (Keytruda) significantly improved disease-free survival over placebo in early-stage non-small cell lung cancer patients, regardless of PD-L1 expression status, the company said on Monday.
In the interim analysis, Merck's checkpoint inhibitor also improved disease-free survival over placebo in the subgroup of patients with PD-L1 expression in at least 50 percent of tumor cells but didn't reach statistical significance according to a prespecified statistical plan, the company said.
In Keynote-091, Merck, the European Organization for Research and Treatment of Cancer, and the European Thoracic Oncology Platform, are comparing pembrolizumab against placebo in 1,177 patients with stage IB to IIIA NSCLC after surgery. Disease-free survival in all comers and in high PD-L1 expressers are coprimary endpoints in the study.
After this interim analysis of the coprimary endpoints, Merck will continue to analyze disease-free survival in patients with PD-L1 expression in at least 50 percent of tumor cells and assess overall survival as a secondary endpoint. Merck will also submit data from this trial to regulatory authorities.
"We are encouraged by these results supporting the potential role of Keytruda in stage IB-IIIA non-small cell lung cancer," Roy Baynes, senior VP, head of global clinical development, and chief medical officer at Merck Research Laboratories, said in a statement. He added that the company will share data from this study at an upcoming medical meeting.
In contrast to the findings of Keynote-091, data from the IMPower010 trial led to the US Food and Drug Administration's approval last year of Roche/Genentech's checkpoint inhibitor atezolizumab (Tecentriq) for adjuvant treatment of PD-L1-positive NSCLC patients after surgery and platinum-based chemotherapy. The FDA stipulated patients must have PD-L1 expression in at least 1 percent of tumor cells to receive the immunotherapy, even though exploratory analysis in the IMPower010 trial had shown that patients with high PD-L1 expression had far better outcomes than those with low-to-intermediate levels of PD-L1 expression.
There are important differences between the two trials, however. Unlike Keynote-091, which compares pembrolizumab to placebo, the IMPower010 trial compares atezolizumab against best supportive care in the adjuvant NSCLC setting.