New Drug Shown to Reduce Size in Both Injected and Metastasized Melanoma Tumors

The analysis documented tumor-level responses from a pivotal phase 3 study evaluating the agent, called talimogene laherparepvec, in patients with injectable unresected stage IIIB, IIIC, or IV melanoma compared to granulocyte-macrophage colony-stimulating factor (GM-CSF). The findings were presented March 14, 2014, at the Society of Surgical Oncology (SSO) 67th annual Cancer Symposium in Phoenix (AZ, USA).

Talimogene laherparepvec, developed by Amgen (Thousand Oaks, CA, USA), is a research oncolytic immunotherapeutic agent designed to selectively replicate in tumor tissue and to initiate a systemic antitumor immune response. Of the 295 patients treated with talimogene laherparepvec, almost 4,000 tumor lesions were tracked for this analysis. Half of these lesions were injected with the drug at least once, while the rest were not injected, including visceral tumor lesions (tumors involving solid organs such as the lungs and liver). The study’s findings showed a 50% or greater reduction in tumor size in 64% of injected tumors. Furthermore, one-third of uninjected nonvisceral tumors, and 15% of visceral tumors were also reduced by at least 50%. There were 35 melanoma-related surgeries performed during this trial of which 30% successfully removed all residual disease.

The most frequently seen adverse events in the phase 3 study were fatigue, chills and pyrexia. The most common serious adverse events include disease progression in both groups, and cellulitis and pyrexia in the talimogene laherparepvec group. Serious adverse events occurred in 26% of talimogene laherparepvec patients and 13% of GM-CSF patients. Immune-mediated events were reported infrequently.

“These data add to the body of evidence supporting talimogene laherparepvec’s local and distant effect, and its potential ability to stimulate a systemic antitumor immune response,” said Sean E. Harper, MD, executive vice president of research and development at Amgen. “Melanoma remains a devastating and difficult-to-treat disease, and talimogene laherparepvec continues to demonstrate encouraging results in this setting.”

The agent is injected directly into tumor tissue and is intended to replicate preferentially in tumor cells causing lytic cell death and releasing an array of tumor-derived antigens. Talimogene laherparepvec is also engineered to express granulocyte-macrophage colony-stimulating factor (GM-CSF), a white blood cell growth factor, which can help to activate the immune system. The aim of this combination of actions is to initiate a systemic antitumor immune response that targets tumor cells throughout the body.

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