US-based Amgen has reported interim overall survival (OS) results from a Phase III trial assessing the safety and efficacy talimogene laherparepvec (T-VEC) in patients with unresected stage IIIB, IIIC or IV melanoma compared to granulocyte-macrophage colony-stimulating factor (GM-CSF).

As per the predefined interim analysis of the global, randomised, open-label Phase III trial, median OS was 23.3 months in the talimogene laherparepvec arm compared with 19 months in the GM-CSF arm.

According to the company, differences in survival rates were pronounced in the subset of patients with stage IIIB, IIIC or IV M1a disease or who received talimogene laherparepvec as first-line treatment, each comprising about 50% of the trial population.

Amgen executive vice-president of research and development Sean Harper said: “The interim overall survival subset results complement the durable response data we reported earlier this year and these endpoints appear to correlate with each other in terms of where the most benefit is being seen in this trial.”

“A favourable trend in overall survival was observed in patients who received talimogene laherparepvec.”

In the trial, the most frequently observed adverse events were fatigue, chills and pyrexia, while the most common serious adverse events include disease progression in both arms, and cellulitis and pyrexia in the talimogene laherparepvec arm, which occurred in 26% of talimogene laherparepvec patients and 13% of GM-CSF patients.

Rush University Medical Center in Chicago professor Howard Kaufman said: “A favourable trend in overall survival was observed in patients who received talimogene laherparepvec and the trend was pronounced in patients with stage III and IV M1a disease where an important clinical need exists for patients whose disease has not yet spread to distant organs.”

In the trial, patients were randomised 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, while the treatment could last for about 18 months.

Talimogene laherparepvec, an investigational oncolytic immunotherapy, is injected directly into tumour tissue and is intended to replicate preferentially in tumour cells causing lytic cell death and releasing an array of tumour specific antigens.

Image: Histopathologic image of malignant melanoma. Photo: courtesy of KGH.