An FDA advisory panel on Wednesday voted 22-1 in favour of approval of Amgen's talimogene laherparepvec (T-Vec) for the treatment of metastatic melanoma. Earlier this week, FDA reviewers suggested that the therapy should not be considered for accelerated approval and questioned whether clinical trial data demonstrated that the drug improves overall survival.
In previously reported data, Amgen disclosed that T-Vec met its primary endpoint of durable response rate versus granulocyte-macrophage colony-stimulating factor (GM-CSF). However, the drugmaker announced earlier this month that top-line results of a Phase III trial of patients with melanoma did not uncover a benefit of T-Vec on overall survival compared to GM-CSF. "Considering that melanoma patients now have multiple treatment options, it is unclear whether [T-Vec] offers an acceptable benefit-risk profile for the proposed indicated population," stated FDA staff on April 27.
Although the panel also questioned whether T-Vec prolonged survival, the panellists acknowledged that in Amgen's trial, a subset of patients had a durable response to the drug. While overall 16 percent of patients displayed a durable response, 33 percent of participants with stage IIIB or IIIC disease exhibited a durable response.
Further, Amgen presented data showing that T-Vec ablated 995 of 2116 melanoma injected tumours, in addition to 212 tumours that were not injected. The panel questioned whether the data were sufficiently robust enough to confirm that a sustained immune response occurred and pondered whether tumour shrinkage would translate into a clinically meaningful benefit for patients.
Sean Harper, executive vice president of research and development at Amgen, commented that the company believes the study data "demonstrated a statistically significant improvement in the primary endpoint—durable response rate—which was associated with clinical benefit to patients", adding that "even with the remarkable recent advances in the melanoma field, there is still a need for additional treatment options."
The FDA is expected to issue a decision on whether to clear T-Vec on October 27, after postponing the decision from July 28.
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