Amgen has announced top-line results from the phase 3 trial in melanoma, which has evaluated the efficacy and safety of Talimogene Laherparepvec for the treatment of unresected stage IIIB, IIIC or IV melanoma compared to treatment with subcutaneous granulocyte-macrophage colony-stimulating factor ( GM-CSF ).

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, a key secondary endpoint of the study, is event driven. A pre-planned interim analysis conducted with the analysis of DRR has shown an overall survival trend in favor of Talimogene Laherparepvec as compared to GM-CSF.

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.

This trial was a global, randomized, open-label, phase 3 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.

Talimogene Laherparepvec is an investigational oncolytic immunotherapy 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.

Source: Amgen, 2013