IMLYGIC or T-VEC Melanoma Drug Shrinks Tumors in Phase III Trial

FDA Approved Imlygic - T-VEC for clinical use in melanoma.

by Dr. C.H. Weaver M.D. updated 1/2019

An advisory panel to the U.S. Food and Drug Administration (FDA) recommended approval of Imlygic or T-VEC (talimogene laherparepvec) for the treatment of metastatic melanoma.

Of the more than one million new diagnoses of skin cancer each year, roughly 76,000 involve melanoma. More than 9,000 people die of melanoma each year in the United States. Melanoma is dangerous because it is more likely than other types of skin cancer to spread (metastasize) to other parts of the body. Important progress has been made in the treatment of this disease in recent years, but researchers continue to seek new and more effective drugs.

The recommendation for approval is based on findings from a Phase III clinical trial in which T VEC produced durable responses in people with advanced melanoma.

The trial results demonstrated that T-VEC is active against advanced melanoma, and, according to the advisory panel, justify FDA approval of T-VEC.Melanoma is dangerous because it is more likely than other types of skin cancer to spread (metastasize) to other parts of the body. Researchers continue to seek new and more effective drugs for the treatment of melanoma.

T-VEC Investigational Melanoma Drug Shrinks Tumors in Phase III Trial

T-VEC is a type of immunotherapy that uses a specially designed virus to destroy cancer cells. It is injected directly into the tumor. After acting locally within the tumor, it is intended to prompt an immune response against cancer cells elsewhere in the body.

To evaluate T-VEC for the treatment of advanced melanoma, researchers conducted a Phase III clinical trial that enrolled more than 400 patients. The patients had Stage IIIB, IIIC, or IV melanoma that could not be surgically removed. Patients were treated with either T-VEC or GM-CSF for up to 18 months.

The primary outcome of interest was a durable response (a partial or complete elimination of cancer that lasted for at least six months).

  • Durable responses occurred in 16% of patients in the T-VEC group and 2% of patients in the GM-CSF group. In the T-VEC group, durable responses were most common among patients with Stage III melanoma.
  • The overall response rate was 26% among patients in the T-VEC group and 6% among patients in the GM-CSF group.
  • The most common side effects of T-VEC were fatigue, chills, and fever.

Using data from the phase III study researchers additionally analyzed 3,219 tumor lesions (in 286 patients) to study the response to the drug in injected versus non-injected tumors. Overall, 2,043 lesions were injected with T-VEC at least once, 1,022 were un-injected non-visceral, and 154 were un-injected visceral lesions. The results showed

  • 64 percent of injected tumors shrank by half
  • 16 percent of un-injected visceral lesions shrank by half.
  • A total of 6 patients converted from inoperable to operable melanoma after receiving T-VEC.
  • In total, 37 surgeries were performed during the course of the trial: 15 resulted in no evidence of disease and 3 showed a pathologic complete response.

The vaccine shrank tumors that were directly injected as well as those that were not injected—indicating that the vaccine was triggering the immune system to fight the distant tumors. The researchers concluded that this promising new agent warrants further study.

These results demonstrate that T-VEC is active against advanced melanoma. Study participants will continue to be followed in order to assess the effect of T-VEC on overall survival. There is currently a trend toward improved overall survival with T-VEC, but final survival results require longer follow-up.


  1. Amgen to Discuss Details of the Biologics License Application for Talimogene Laherparepvec For Patients With Metastatic Melanoma [news release]. Amgen website. Available at: . Accessed April 30, 2015.
  2. Andtbacka RHI, Collichio FA, Amatruda T et al. OPTiM: A randomized phase III trial of talimogene laherparepvec (T-VEC) versus subcutaneous (SC) granulocyte-macrophage colony-stimulating factor (GM-CSF) for the treatment (tx) of unresected stage IIIB/C and IV melanoma. Presented at the 49thAnnual Meeting of the American Society of Clinical Oncology. May 31-June 4, 2013; Chicago, IL. Abstract LBA9008.
  3. Andtbacka RH, Ross MI, Delman K, et al: Responses of injected and uninjected lesions to intralesional tal-imogene laherparepvec (T-VEC) in the OPTiM Study and the Contribution of Surgery to Response. Presented at the Society of Surgical Oncology Cancer Symposium in Phoenix, Arizona March 12-15, 2014. Abstract 52.