Oncolytiques

Oncolytiques are therapeutic agents designed to selectively infect, replicate in, and destroy cancer cells while limiting damage to normal tissues. The most studied oncolytics are genetically modified viruses, though non-viral approaches are explored. They combine direct oncolysis with stimulation of anti-tumor immunity: viral replication kills tumor cells and releases tumor antigens and inflammatory signals that recruit immune cells; some oncolytics are engineered to express immune-modulating proteins such as GM‑CSF to enhance this response. The selectivity often relies on cancer-specific defects in antiviral defenses or modifications that restrict replication to the tumor microenvironment.

Common platforms include herpes simplex virus, adenovirus, vaccinia, measles, and reovirus, with talimogene laherparepvec (T-VEC, an HSV-1 derived virus expressing GM‑CSF) being the best known example. T-VEC has regulatory approval for melanoma in several regions; other agents are in various stages of clinical testing, including combinations with immune checkpoint inhibitors.

Delivery and limitations: intratumoral administration is common; systemic delivery faces barriers such as pre-existing immunity and rapid clearance. Tumor accessibility and heterogeneity influence effectiveness. Immune responses may neutralize subsequent doses. Safety profile is generally favorable; most side effects are flu-like symptoms or local injection-site reactions; serious risks include viral dissemination in immunocompromised individuals.

Outlook: research aims to enhance tumor targeting, expand approved indications, and combine with other systemic therapies to improve outcomes. Biomarkers to select patients and monitor responses are under investigation.