Early-stage study results detailed at the ASCO annual meeting suggest that Merck & Co.'s PD-1 inhibitor Keytruda (pembrolizumab) is effective as monotherapy in heavily pre-treated patients with recurrent or metastatic head and neck cancer, regardless of PD-L1 expression status. Data showed that the overall response rate (ORR) was 24.8 percent, with similar rates observed among patients with or without human papillomavirus (HPV) infection, a risk factor for the disease.
"The totality of the data...furthers our understanding of the clinical potential of Keytruda in head and neck cancer, regardless of PD-L1 expression or HPV status," commented Roger Dansey, head of global clinical oncology development at Merck Research Laboratories. "Based on the results observed to date, we are advancing multiple registrational studies in head and neck cancer, including randomised evaluations of overall survival (OS) and progression-free survival (PFS) with Keytruda, as monotherapy and in combination with chemotherapy, compared to standard of care," Dansey added.
The ongoing Phase Ib KEYNOTE-012 trial included 132 pre-treated patients with recurrent or metastatic head and neck cancer. Primary endpoints of the study, whose results were first presented at last year's ASCO annual meeting, include overall safety, tolerability and anti-tumour activity of Keytruda monotherapy, while secondary endpoints will assess PFS, OS and duration of response.
The latest results showed that 56 percent of evaluable patients displayed tumour shrinkage, including shrinkage of at least 30 percent in a quarter of the participants. The company said the median duration of response was not reached, but that 86 percent of those who had achieved a response to treatment continued to do so at the time of analysis. Regarding HPV status, Merck reported that the ORR was 20.6 percent among HPV-positive patients and 27.2 percent among those with HPV-negative disease.
Commenting on the findings, lead investigator Tanguy Seiwert said "this is remarkable because we don't usually see this level of activity with new agents," which he pointed out "have a track record of failure." Seiwert noted that currently "the only thing that works is [Eli Lilly's Erbitux (cetuximab)] and [Keytruda] looks at least twice as good."
Keytruda became the first PD-1 inhibitor approved by the FDA following its clearance last year for the treatment of advanced or unresectable melanoma. Earlier this month, the European Medicines Agency's Committee for Medicinal Products for Human Use issued a positive opinion recommending approval of the therapy for advanced melanoma in the first-line setting, as well as for previously treated patients. Merck also recently announced that Keytruda was submitted for FDA approval to treat advanced non-small-cell lung cancer, an indication for which the medicine has been granted breakthrough therapy status.
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