US-based Amgen has released positive results from its Phase III trial evaluating talimogene laherparepvec in patients with injectable unresected stage IIIB, IIIC or IV melanoma compared with granulocyte-macrophage colony-stimulating factor (GM-CSF).
Results showed that talimogene laherparepvec reduced the size of injected tumours and also non-injected tumours that had metastasised to other parts of the body.
Talimogene laherparepvec is an investigational oncolytic immunotherapy designed to selectively replicate in tumour tissue and to start a systemic anti-tumour immune response.
Out of the 295 patients treated with talimogene laherparepvec, almost 4,000 tumour lesions were tracked for the analysis.
The company said that half of these lesions were injected with talimogene laherparepvec at least once, while the rest were not injected, including visceral tumour lesions.
Results of the Phase III trial showed a 50% or greater reduction in tumour size in 64% of injected tumours, and in addition, one-third of uninjected non-visceral tumours as well as 15% of visceral tumours were also reduced by at least 50%.
During the trial, about 35 melanoma-related surgeries were conducted, with 30% successfully having all residual disease removed.
Fatigue, chills and pyrexia were the most frequently observed adverse events in the Phase III trial and the most common serious adverse events include disease progression in both groups, and cellulitis and pyrexia in the talimogene laherparepvec group.
The company said that serious adverse events occurred in 26% of talimogene laherparepvec patients and 13% of GM-CSF patients.
Amgen executive vice-president of R&D Sean Harper said: "Melanoma remains a devastating and difficult-to-treat disease, and talimogene laherparepvec continues to demonstrate encouraging results in this setting."
Talimogene laherparepvec 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-derived antigens.
It is also engineered to express granulocyte-macrophage colony-stimulating factor (GM-CSF), a white blood cell growth factor, which can help to activate the immune system.