A new weapon against deadly melanoma became available on October 27 when the Food and Drug Administration (FDA) approved Imlygic (talimogene laherparepvec) for the treatment of the malignancy. Imlygic is the first FDA-approved oncolytic virus therapy for the cancer; it is a genetically modified live oncolytic herpes virus therapy that is used to treat melanoma lesions that cannot be removed completely by surgery. Imlygic is injected directly into the melanoma lesions, where it divides within the malignant cells and causes them to rupture and die.
Skin cancer is the most common form of cancer in the US, and melanoma is the leading cause of skin cancer related deaths, and is most often caused by exposure to ultraviolet (UV) light. Approximately 74,000 Americans will be diagnosed with melanoma and nearly 10,000 will die from the disease in 2015, according to the National Cancer Institute. “Melanoma is a serious disease that can advance and spread to other parts of the body, where it becomes difficult to treat,” explained Karen Midthun, M.D., director of the FDA’s Center for Biologics Evaluation and Research. She added, “This approval provides patients and healthcare providers with a novel treatment for melanoma.”
Imlygic is manufactured by BioVex Inc., a subsidiary of Amgen Inc., based in Thousand Oaks, California. Amgen expects the average cost of Imlygic therapy to be about $65,000, and that it will be available to patients in the United States within a week. The company said it is evaluating the drug in combination with other immunotherapies in advanced melanoma and other solid tumor cancers. A treatment course with Imlygic involves a series of injections into the melanoma lesions. After the initial injection, a second dose is given three weeks later, followed by additional doses every two weeks for at least six months, unless other treatment is required or until there are no remaining injectable lesions to treat.
The safety and effectiveness of Imlygic were evaluated in a multicenter study of 436 metastatic melanoma patients who had lesions that could not be surgically removed. The melanoma lesions in the skin and lymph nodes were treated with Imlygic or an alternative therapy for at least six months, or until there were no remaining injectable lesions. The study found that 16.3% of the patients who received Imlygic experienced a decrease in size of their skin and lymph node lesions, lasting for a minimum of six months, compared to 2.1% of the study participants administered the alternative therapy. However, on the down side, Imlygic has not been shown to improve overall survival or to have an effect on melanoma that has spread to the brain, bone, liver, lungs, or other internal organs.
The most common side effects observed were fatigue, chills, fever, nausea, flu-like symptoms, and pain at the injection site. Imlygic is a modified live oncolytic herpes virus therapy; therefore, herpes virus infection can also occur. Due to this factor, Imlygic should not be given to individuals with suppressed immune systems or who are pregnant.