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Immunotherapies use the immune system to fight cancer, cancers like melanoma have found ways to turn off the immune system, allowing them to resist treatments and leading to recurrence. University of Colorado Cancer Center describes a promising strategy to remove one of melanoma’s defenses: Researchers added retinoic acid to standard-of-care treatment and were able to turn off myeloid-derived suppressor cells MDSCs that turn off the immune system, leading to more immune system activity directed at melanoma.
The immune response and MDSCs must balance each other: the immune system will fight an infection if MDSCs is shut down. Melanoma induces these cells to be around the tumor microenvironment. MDSCs are immature, undifferentiated cells that are produced in the bone marrow. When healthy, MDSCs quickly mature into cell types that aid immune function. Cancers like melanoma encourage MDSCs to remain immature, and this population of immature MDSCs turns off the immune system.
Retinoic acid is a compound derived from the breakdown of Vitamin A. It encourages cells to differentiate, transitioning from stem-like cells into the mature cells the body needs for structure and function. Retinoic acid is a common ingredient in topical acne treatments and is also used to treat acute promyelocytic cancer. The form of retinoic acid called ATRA could force MDSCs to mature, switching their function from immune suppression to immune support.