Researchers at Loyola University Chicago Stritch School of Medicine have found that the combination of new immunotherapies with radiation therapy offers a promising therapeutic approach for melanoma patients.
The study, “The integration of radiation therapy and immunotherapy in melanoma management,” was published in the Journal of Radiation Oncology.
Melanoma, an aggressive form of skin cancer, exhibits intriguing immunological phenomena that suggest immunotherapeutic approaches can be employed to treat patients. Extensive data documents the interface between the immune system and the disease.
Spontaneous regression of melanoma is a rare but well-documented occurrence. The regression has been observed both in primary melanoma lesions and in metastatic melanoma, but only the latter has been shown to be a positive prognostic factor for patients. Although it is unclear why spontaneous regression of melanoma occurs, it is known that the immune system plays an important role in this process.
One other key observation that supports the involvement of the immune system in melanoma is the abscopal effect: a rare phenomenon defined as a spontaneous regression of metastatic melanoma following locally-directed treatment, often radiation therapy.
The radiation, which reduces tumor size by damaging the tumor cells’ DNA, seems to activate a systemic immune response that is able to attack cancer cells – not only in the site receiving treatment, but also in the remaining parts of the body.
Dr. James S. Welsh, a professor in the department of radiation oncology at Stritch School of Medicine, and the lead author of the recent study, witnessed the abscopal effect when he administered radiation therapy to a melanoma patient with bone and liver metastasis. Although the treatment was used to decrease the tumor size in the patient’s femur and reduce risk of fracture, the cancer completely regressed three months after the radiation was administered.
Considering the role of the immune system in melanoma, a large number of immunotherapies are being tested in patients. Checkpoint inhibitors, a class of drugs that allow immune cells to efficiently fight cancer cells by removing the inhibitory signals that impair their function, have been gaining particular attention.
Combining the checkpoint inhibitors or other immunotherapeutic agents with chemotherapy is being increasingly used and is showing encouraging results.
“Perhaps, truly successful strategies will involve combinations of different agents such as cytokines and checkpoint inhibitors,” the study concluded. “From this review, it appears quite possible that radiation therapy will also be an integral component of such successful strategies.”
