Amgen's closely-watched cancer vaccine T-Vec has again impressed in late-stage trials for melanoma.

The biotech major has presented results from a retrospective analysis of patients with metastatic melanoma injected with T-Vec, also known as talimogene laherparepvec. The oncolytic immunotherapy is injected directly into tumour tissue then replicates until the membrane of the cancer cells rupture, thereby destroying them.

The data showed a 50% or greater reduction in size in 64% of injected tumours, one-third of uninjected non-visceral tumours, and 15% of visceral tumours were also reduced by at least 50%. There were 35 melanoma-related surgeries performed during this trial of which 30% successfully removed all residual disease.

Amgen R&D chief Sean Harper said "these data add to the body of evidence supporting [T-Vec's] local and distant effect, and its potential ability to stimulate a systemic anti-tumour immune response. Noting that "melanoma remains a devastating and difficult-to-treat disease", T-Vec "continues to demonstrate encouraging results in this setting".

Observers are now waiting for survival data which is likely to be published in the next few months and are particularly excited about its potential as a combination treatment. T-Vec is already being evaluated in a combo with Bristol-Myers Squibb's melanoma drug Yervoy (ipilimumab).

Also last month, Amgen announced a Phase Ib/II study of T-Vec in combination with Merck & Co's experimental anti-PD-1 immunotherapy MK-3475 for mid-to-late-stage melanoma.