The US Food and Drug Administration (FDA) has approved its first oncolytic virus therapy, talimogene laherparepvec (Imlygic), a drug for the treatment of patients with melanoma lesions in the skin and lymph nodes.
Talimogene laherparepvec is a genetically modified live oncolytic herpes virus therapy that is injected directly into melanoma lesions where it replicates inside the cancer cells producing granulocyte-macrophage colony-stimulating factor (GM-CSF). The drug causes cell death and then rupture, which releases tumor-derived antigens and GM-CSF, which may promote an antitumor response.
The FDA made the approval based on the efficacy results of the phase III OPTiM study, which included 436 patients with unresectable advanced melanoma. Patients were randomly assigned to talimogene laherparepvec intratumorally or GM-CSF every 14 days for 28 days. After the initial injection, talimogene laherparepvec was administered again 3 weeks later, followed by additional doses every 2 weeks for at least 6 months. The primary endpoint of the analysis was durable response rate.
More patients assigned to talimogene laherparepvec achieved a durable response—a decrease in size of their skin and lymph node lesions—compared with patients assigned GM-CSF (16.3% vs 2.1%; P < .001). Patients assigned talimogene laherparepvec had a response that lasted a minimum of 6 months. Of the patients achieving a durable response, 29.1% had a durable complete response and 70.8% had a durable partial response. The median time to response among patients assigned talimogene laherparepvec was 4.1 months.
“Advanced melanoma remains a complex disease to treat, requiring the use of several modalities over the course of a patient's therapeutic journey,” said OPTiM trial principal investigator Howard L. Kaufman, MD, associate director for clinical science at the Rutgers Cancer Institute of New Jersey and president of the Society for Immunotherapy of Cancer, in a press release. “As an oncolytic viral therapy, Imlygic has a unique approach, and provides another option for treating eligible patients with unresectable disease that has recurred after initial surgery.”
The most common adverse events seen in the OPTiM study were fatigue, chills, fever, nausea, flu-like symptoms, and pain at the injection site.
The FDA noted that talimogene laherparepvec was not associated with any improvement in overall survival and has not been shown to have an effect on melanoma spreading to the brain, bone, liver, lungs, or other internal organs. In addition, because the injection include a live herpes virus, herpes virus infection can also occur; therefore, the treatment should not be given to individuals with suppressed immune systems or who are pregnant.