Merck has announced that the Phase III KEYNOTE-604 trial met with mixed results fulfilling one of its dual primary endpoints.

The study involved assessing the efficacy of cancer drug Keytruda in combination with chemotherapy (etoposide plus cisplatin or carboplatin) for treating extensive-stage small cell lung cancer (ES-SCLC).

It identified a significant improvement in progression-free survival (PFS) in patients treated with Keytruda in combination with chemotherapy over patients undergoing chemotherapy alone.

The final analysis also observed an increase in overall survival (OS) for patients treated with the combination.

However, the results did not fulfil statistical significance as per the pre-specified plan.

The KEYNOTE-604 study enrolled 453 patients.

Merck Research Laboratories chief medical officer, senior vice-president and head of global clinical development Dr Roy Baynes said: “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.

“We sincerely thank the patients and investigators for their participation in this study and are committed to helping patients who face difficult-to-treat types of lung cancer.”

The company discussed the trial results with regulatory authorities and will present it at an upcoming medical meeting.

Keytruda is currently indicated for treating five indications in lung cancer. Merck is continuing to study the drug to broaden its application. The comprehensive clinical programme is expected to feature more than 10,000 patients across 20 Merck-sponsored clinical studies.

It is estimated that SCLC accounts for around 10% to 15% of all lung cancers and has a very low five-year survival rate.