Herpes Virus-Immunotherapy Combo Improves Melanoma Treatment

Patients with drug-resistant melanoma treated with a herpes virus-pembrolizumab drug combination showed a complete or partial response.

Melanoma is known to be a very aggressive and deadly form of skin cancer. Treatment can be challenging due to the likelihood of metastasis and drug-resistance.

A new study published by Cell shows that a combination of immunotherapy and a herpes virus could be a promising treatment for advanced melanoma.

In the 2-year study, approximately two-thirds of patients with advanced melanoma responded to a novel combination of pembrolizumab (Keytruda) plus the herpes virus talimogene laherpareovec (T-VEC). Patients in the study were resistant to monotherapy with the drugs, highlighting the efficacy of the new combination.

Importantly, the authors found that the side effects were manageable, with a similar safety profile to pembrolizumab or T-VEC monotherapy, according to the study.

T-VEC is a modified version of the herpes simplex virus that causes cold sores, but it is safe to use in humans and has been approved to treat melanoma. T-VEC uses a protein to bring immune cells to the cancer, which results in cell death.

Pembrolizumab is an immunotherapy approved to treat numerous cancers, including melanoma. It harnesses the immune system to increase the body’s natural ability to fight disease.

The authors report that patients whose melanoma is resistant to pembrolizumab often lack CD8+ in their tumors. The researchers hypothesize that patients whose tumors are resistant to pembrolizumab may benefit from the combination therapy, as T-VEC attracts CD8+ immune cells to the tumors, according to the study. This action allows pembrolizumab to launch a full attack against the cancer.

Included in the phase 1 study were 21 patients with advanced melanoma who received T-VEC injections for 6 weeks plus infusions of pembrolizumab.

The authors discovered that 62% of patients achieved a partial or complete response to therapy, with some tumors no longer detectable, according to the study.

These results suggest that this novel combination therapy may be able to provide an alternative therapy for patients with melanoma whose tumors are unresponsive to current therapies.

Due to the promising findings, the authors are also testing the combination among patients with head, neck, and colon cancers, according to the study.

“In conclusion, the high response rate in this phase 1 clinical trial and the mechanistic changes documented in patient biopsies suggest that the combination of talimogene laherparepvec and pembrolizumab may be able to overcome some limitations of either single-agent therapy and provide responses beyond what would be expected with either talimogene laherparepvec or pembrolizumab administered alone,” the authors concluded.