UCLA scientists have developed a potential new treatment for melanoma that has shown promising early clinical results. In a two-year UCLA-led study, nearly two-thirds of people with advanced melanoma responded positively to a treatment that combines the immunotherapy drug keytruda (pembrolizumab) with a herpes virus called T-VEC (talimogene laherpareovec).
Researchers found that the treatment’s side effects were manageable, and comparable to side effects for people who took either keytruda or T-VEC as a standalone treatment.
T-VEC is a genetically modified version of the herpes simplex virus that causes cold sores but is safe to use. T-VEC has already been approved for the treatment of melanoma and it works both by directly killing cancer cells and using a protein that attracts immune cells into the cancers.
Keytruda has become a standard-of-care treatment for advanced melanoma, and it is also being used to treat non-small-cell-lung cancer, cancers of the head, neck, kidney and bladder, and Hodgkin’s disease. It works by taking the “brakes” off of the body’s immune system, enabling it to attack cancer.
According to the study authors people whose melanoma does not respond to keytruda often lack a type of T cell called CD8+ in their tumors; the lack of CD8+ cells seems to prevent immunotherapy drugs from working. But the researchers believe those people might benefit from a combination therapy, because T-VEC attracts CD8+ immune cells to the tumors and keytruda allows them to attack the cancer cells.
The phase 1 clinical trial evaluated 21 people with advanced melanoma. Researchers injected patients’ melanoma tumors with T-VEC for six weeks and then gave them infusions of keytruda. Sixty-two percent of the patients had a partial or complete response, meaning that their tumors either shrank or were no longer detectable.
The combination therapy could provide an alternative treatment for people with melanoma whose tumors don’t respond to other therapies. It also being tested in people with head, neck and colon cancers.