NEW YORK – The European Commission on Tuesday approved Merck's Keytruda (pembrolizumab) plus Genentech's Herceptin (trastuzumab) and chemotherapy as first-line treatment for HER2-positive gastric and gastroesophageal cancer patients whose cancers express PD-L1.
The approval, which follows a positive opinion from the European Medicines Agency's Committee for Medicinal Products for Human Use in July, is based on the results of the Phase III KEYNOTE-811 trial, in which Keytruda plus Herceptin and chemo improved patients' progression-free survival and objective response rates compared to Herceptin and chemo alone.
Although the clinical trial did not limit patient enrollment to those whose cancers expressed PD-L1, more than 80 percent of patients in the trial did have tumors that were PD-L1 positive, according to Merck.
In 2021, the US Food and Drug Administration approved Keytruda plus Herceptin and chemo for this patient population regardless of PD-L1 expression. But recently, Merck said it was working with the FDA to limit the indication to the biomarker-defined population based on updated data from KEYNOTE-811 showing that the benefit in PD-L1 expressors was driving the benefit seen in all comers.
The European approval — which makes the combination available to eligible patients in the EU's 27 member states plus Iceland, Liechtenstein, Norway and Northern Ireland — limits the eligible population to those gastric and gastroesophageal cancer patients whose cancers express PD-L1 with a combined positive score of at least one.
Merck plans to present updated date from KEYNOTE-811 at the European Society for Medical Oncology annual meeting this fall.