How immunotherapy works, which drugs are used for melanoma, squamous cell, basal cell, and Merkel cell cancers, and the side effects to watch for.
Immunotherapy helps a person's own immune system find and attack cancer cells. Since 2011 it has changed the outlook for advanced melanoma more than any other treatment. It now has a place in several other skin cancers too.
Immune cells carry natural brakes called checkpoints. Cancer cells press on those brakes to hide. Checkpoint inhibitors block the brakes so immune cells can go back to work. These drugs are given through a vein, usually every few weeks.
Imiquimod is a cream that triggers an immune reaction in the skin where it is applied. Doctors use it for some superficial basal cell cancers and actinic keratoses, and for selected stage 0 melanomas where surgery isn't practical.
Talimogene laherparepvec (T-VEC) is a modified virus injected directly into melanoma tumors in the skin or lymph nodes that can't be removed with surgery. A newer injected virus therapy, vusolimogene oderparepvec, is given together with nivolumab for advanced melanoma that has stopped responding to PD-1 inhibitors.
Lifileucel is a tumor-infiltrating lymphocyte (TIL) therapy. A surgeon removes a piece of the tumor. A lab grows the immune cells found inside it into the billions, and the care team returns them by infusion after a short course of chemotherapy. It is used for advanced melanoma after other treatments, and only at specialized centers.
High-dose interleukin-2 and interferon were the main immunotherapies before checkpoint inhibitors arrived. Interferon is rarely used today. Interleukin-2 still has a limited role.
Releasing the immune system's brakes can also turn it against healthy organs. The skin, gut, liver, lungs, and hormone glands are affected most often. Most of these reactions can be managed when they're caught early, but some are serious. Report new diarrhea, shortness of breath, rash, or severe fatigue to the care team right away.
The right choice depends on the type and stage of the cancer and on a person's overall health. A medical oncologist who treats skin cancer can explain the options. Drug approvals change often. This article reflects the American Cancer Society treatment summaries as revised through August 2026.
