Earlier today researchers released top-line results from the Phase III trial in melanoma, evaluating the efficacy and safety of talimogene laherparepvec (Amgen; T-VEC, originally called OncovexGM-CSF, the trial drug was initially under development by BioVex Inc, Oxford, UK, until it was purchased by Amgen in January 2011 and renamed). The trial drug is investigated for the treatment of unresected stage IIIB, IIIC or IV melanoma compared to treatment with subcutaneous granulocyte-macrophage colony-stimulating factor (GM-CSF).
Talimogene laherparepvec herpes simplex virus type 1. The investigational oncolytic immunotherapy is designed to selectively replicate in tumor tissue. Talimogene laherparepvec is injected directly into tumor tissue and then replicates until the membrane of the cancer cells rupture, thereby destroying the cells, in a process known as cell lysis. The virus that was contained in these cells is then released locally in the tumor tissue along with GM-CSF, a white blood cell growth factor that the virus is engineered to express. This is intended to lead to the activation of a systemic immune response to kill tumor cells throughout the body.
The study met its primary endpoint of durable response rate (DRR), defined as the rate of complete or partial response lasting continuously for at least six months. A statistically significant difference was observed in DRR: 16% in the talimogene laherparepvec arm versus 2% in the GM-CSF arm. The analysis of overall survival (OS), a key secondary endpoint of the study, is event driven. A pre-planned interim analysis conducted with the analysis of DRR has shown an OS trend in favor of talimogene laherparepvec as compared to GM-CSF. The OS data is expected to mature in late 2013 in line with previous guidance.
"These are the first Phase III results of this novel approach to cancer therapy," said Sean E. Harper, M.D., executive vice president of Research and Development at Amgen. "A high unmet need exists in melanoma and we believe the innovative mechanism of action of talimogene laherparepvec may offer a promising approach for these patients."
Observed adverse events
The most frequent adverse events observed in this trial were fatigue, chills and pyrexia. The most common serious adverse events include disease progression, cellulitis and pyrexia.
Among the various types of skin cancer, melanoma is the most aggressive and also the most serious. Although melanoma accounts for less than 5% of skin cancer cases, or 132,000 cases globally each year, melanoma accounts for 75% of all skin cancer deaths.
Additional safety and efficacy data will be submitted to the American Society of Clinical Oncology (ASCO) for the 2013 Annual Meeting.
Trial Design (NCT00769704)
This clinical trial was a global, randomized, open-label, Phase III trial to evaluate the safety and efficacy of talimogene laherparepvec compared to a control therapy with GM-CSF in over 400 patients with unresected stage IIIB, IIIC or IV melanoma.
Patients were randomized 2:1 to receive either talimogene laherparepvec intralesionally every two weeks or GM-CSF subcutaneously for the first 14 days of each 28 day cycle. Treatment could last for up to 18 months. Where appropriate, stable or responding patients could receive additional treatment on an extension protocol.
For more information
 Skin Cancers. World Health Organization, last accessed March 8, 2013
 NCT00769704 - Efficacy and Safety Study of OncoVEXGM-CSF Compared to GM-CSF in Melanoma
 Kaufman H, Wagner VJ, Goldsweig H, Yao B, Coffin R. OPTiM: A randomized phase III trial to evaluate the efficacy and safety of talimogene laherparepvec (T-VEC) compared with subcutaneously (sc) administered GM-CSF for the treatment (tx) of unresectable stage IIIb, IIIc, and IV melanoma. General Poster Session, Melanoma/Skin Cancers; J Clin Oncol 30, 2012 (suppl; abstr TPS8604)
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