Talimogene laherparepvec in addition to pembrolizumab for metastatic melanoma

Talimogene laherparepvec is licensed for the treatment of melanoma skin cancer, and is proposed for the treatment of melanoma skin cancer in combination with pembrolizumab. Melanoma is the commonest skin cancer in the UK and is characterised by changes to mole size or shape. Metastatic melanoma is when the cancer has spread outside the original tumour site and is not usually curative. Unresectable cancer means that the tumour cannot be removed by surgery. As survival is poor in those with unresectable or metastatic melanoma skin cancer, additional treatment options are needed.
Talimogene laherparepvec is a type of gene therapy called an oncolytic virus that is administered intralesionally. It is derived from herpes simplex virus 1 (the cold sore virus), and is modified so that it can infect melanoma cells and multiply inside the cells until it overwhelms and kills them. Pembrolizumab is an antibody (protein) that binds to programmed death-1 receptor (PD-1) to block the binding of programmed death-ligand (PD-L) 1 and PD-L2, increasing the response of a type of immune cell called T-cells, which are then able to kill the cancer cells. Pembrolizumab is administered intravenously. Both treatments have been shown to be effective monotherapies for the treatment of melanoma and it is anticipated that their complementary mechanisms of action could enhance their tumour-killing capacity. Therefore, if licenced, talimogene laherparepvec in combination with pembrolizumab could offer an additional treatment option for patients with unresectable or metastatic melanoma.