A retrospective analysis of a phase III study found that talimogene laherparepvec reduced the size of injected tumors and non-injected metastatic melanoma tumors that had metastasized to other parts of the body.
The study evaluated talimogene laherparepvec in patients with injectable unresected stage IIIB, IIIC or IV melanoma compared to granulocyte-macrophage colony-stimulating factor. Full results were presented during an oral session at the Society of Surgical Oncology Annual Cancer Symposium in Phoenix.
Talimogene laherparepvec is an investigational oncolytic immunotherapy designed to selectively replicate in tumor tissue and to initiate a systemic anti-tumor immune response. It is also engineered to express GM-CSF, a white blood cell growth factor, which can help to activate the immune system.
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 talimogene laherparepvec at least once, while the rest were not injected, including visceral tumor lesions, such as tumors involving solid organs such as the lungs and liver.
The results showed a 50 percent or greater reduction in tumor size in 64 percent of injected tumors. In addition, one-third of uninjected non-visceral tumors, and 15 percent of visceral tumors were also reduced by at least 50 percent. There were 35 melanoma-related surgeries performed during this trial of which 30 percent successfully removed all residual disease.
The most frequently observed adverse events in the phase III 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 percent of talimogene laherparepvec patients and 13 percent of GM-CSF patients. Immune-mediated events were reported infrequently.
