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FDA Advisors Recommend Approval of Skin Cancer Immunotherapy
The skin cancer immunotherapy talimogene laherparepvec (T-Vec, Amgen) showed enough efficacy in the treatment of melanoma to receive marketing approval, an independent advisory panel to the FDA has ruled.
The panel voted 22 to 1 supporting approval of the treatment, an engineered virus that kills cancer cells when injected into tumors and also primes the immune system to attack the disease.
The recommendation comes 2 days after FDA staff expressed concerns over the design and results of a key study of T-Vec and raised questions about the interpretation of data from a late-stage trial. At that time, the reviewers said it was unclear whether the treatment improved overall survival.
T-Vec is built out of a herpes simplex virus that has been engineered to produce granulocyte macrophage colony-stimulating factor (GM-CSF), a growth factor that stimulates stem cells to produce immune cells. As an immunotherapy, T-Vec is injected directly into tumors. There, it replicates inside the tumor cells, causing them to rupture and die. The cell rupture releases tumor-derived particles along with GM-CSF, which stimulates the immune system to attack the cancer cells.
Pivotal clinical data were provided by the phase III OPTiM trial, an open-label, randomized study that compared T-Vec with GM-CSF in 436 patients with advanced melanoma that was not surgically resectable. T-Vec significantly improved the durable response rate (DDR), with 16.3% of treated patients achieving a complete or partial response during the first 12 months of therapy.
Amgen announced on April 29 that T-Vec was more effective in melanoma patients whose cancer had not spread to internal organs.
Analysts believe that, if approved, T-Vec could be the first of a new class of virus-based cancer drugs. Amgen acquired the rights to T-Vec in 2011 from its inventor, Biovex.
The product would enter a market that already has a number of new and effective therapies for melanoma, including ipilimumab (Yervoy, Bristol-Myers Squibb), nivolumab (Opdivo, Bristol-Myers Squibb), and pembrolizumab (Keytruda, Merck).
Sources: Reuters; April 30, 2015; and BioSpace; April 30, 2015.