Mixed Results for Keytruda in Advanced Small-Cell Lung Cancer Trial

Improvement in overall survival fails to reach statistical significance

A phase 3 study comparing pembrolizumab (Keytruda, Merck) plus chemotherapy to chemotherapy alone as a first-line treatment for extensive-stage small-cell lung cancer led to mixed results, Merck announced. The KEYNOTE-604 trial met one of its two primary endpoints by reporting a statistically significant improvement in progression-free survival (PFS), but improvements in overall survival (OS) failed to reach statistical significance.

Pembrolizumab plus chemotherapy (etoposide plus cisplatin or carboplatin) improved PFS compared to chemotherapy alone (hazard ratio [HR], 0.75). At the final analysis of the study, OS also improved for patients treated with pembrolizumab plus chemotherapy compared to chemotherapy alone. However, these OS results did not reach statistical significance under the pre-specified statistical plan (HR, 0.80).

The safety profile of pembrolizumab was consistent with that seen in previous studies. Results will be presented at an upcoming medical meeting and discussed with regulatory authorities.

“Results of KEYNOTE-604 demonstrated the potential of Keytruda, in combination with chemotherapy, to improve outcomes for patients newly diagnosed with extensive-stage small-cell lung cancer, a highly aggressive malignancy,” said Roy Baynes, MD, PhD, senior vice president, head of global clinical development, and chief medical officer of Merck Research Laboratories. The five-year survival rate for U.S. patients diagnosed with any stage of small-cell lung cancer is estimated to be 6%.

KEYNOTE-604, a randomized, double-blind, placebo-controlled phase 3 trial (NCT03066778), enrolled 453 patients. They were randomized to receive either pembrolizumab in combination with etoposide and investigator's choice of platinum chemotherapy (carboplatin or cisplatin), or placebo in combination with etoposide and investigator's choice of platinum chemotherapy (carboplatin or cisplatin).

Source: Merck, January 6, 2020