Laherparepvec

Laherparepvec, also known as talimogene laherparepvec and marketed under the brand name Imlygic, is an oncolytic viral therapy used in the treatment of melanoma. It is a genetically engineered herpes simplex virus type 1 (HSV-1) that is replication-competent but modified to reduce virulence and to express human granulocyte-macrophage colony-stimulating factor (GM-CSF).

Mechanism of action is based on selective infection and lysis of tumor cells followed by stimulation of an anti-tumor immune response. After intralesional injection into melanoma lesions, the virus replicates within tumor cells, causing cell rupture and release of tumor antigens. The expressed GM-CSF recruits and activates dendritic cells, promoting presentation of tumor antigens to T cells and potentially generating systemic anti-tumor immunity, including effects on non-injected lesions.

Indications and administration focus on adults with melanoma that is unresectable or metastatic, with at least one injectable lesion. Treatment is delivered by intralesional injections into accessible tumors on a defined schedule, typically continued for a limited period based on response and tolerability. The approach is generally used as monotherapy or in combination with other therapies in selected patients, depending on regulatory guidance and clinical judgment.

Clinical evidence from pivotal trials demonstrated improvements in durable response rate and, in some analyses, overall survival compared with control therapy in injected melanoma lesions. Regulatory approvals have established its use for eligible patients with injectable cutaneous, subcutaneous, or nodal melanoma lesions.

Safety concerns include flu-like symptoms (fever, fatigue, chills), injection-site reactions, and other inflammatory responses. Because the therapy uses a live HSV-1 vector, there is a risk of herpetic infections and disseminated HSV in severely immunocompromised individuals. Laherparepvec is contraindicated or used with caution in such populations according to labeling.