Io Therapeutics, Inc. announces publication of studies on the company’s RXR agonist compound IRX4204 for breast cancer prevention

SPRING, Texas, March 11, 2026 (GLOBE NEWSWIRE) -- Io Therapeutics, Inc. in Spring, Texas, announces collaborative publication of data from preclinical studies with scientists at The University of Texas MD Anderson Cancer Center demonstrating effectiveness of the retinoid X receptor (RXR) agonist compound IRX4204 in models of prevention of estrogen receptor-negative and triple-negative breast cancers in three different genetically predisposed mouse models.

The research report titled: “Targeting the RXR Pathway for the Prevention of Triple-Negative Breast Cancer”, was led by MD Anderson researchers Cassandra L. Moyer, Ph.D., former postdoctoral fellow; Abhijit Mazumdar, Ph.D., associate professor of Clinical Cancer Prevention; and Powel H. Brown, M.D., Ph.D., professor Clinical Cancer Prevention. The study was published in the March 1, 2026, issue of Cancer Prevention Research.

The studies demonstrate that RXR agonism mediated by IRX4204 significantly delays the formation of mammary tumors in three estrogen receptor-negative mouse models: MMTV-ErbB2, C3(1)SV40-Tag, and Brca1-deficient, with minimal toxicities. In some cases, IRX4204 completely prevented mammary tumor formation. Biomarker analysis revealed that delayed tumors arising after IRX4204 treatment had decreased Ki-67 expression (a marker of how rapidly cancer cells are dividing) and increased immune infiltration of cytotoxic T cells. This supports that IRX4204 has direct inhibitory effects on breast cancer cell growth and promotes cancer cell killing by immune cells. Both mechanisms may be critical for IRX4204 prevention of triple-negative breast cancer. This preclinical data supports the further evaluation of use of IRX4204 for the prevention of estrogen receptor-negative and triple-negative breast cancers.

Dr. Mazumdar stated: “While prophylactic treatment with selective estrogen receptor (ER) modulators and aromatase inhibitors targeting the nuclear ER can prevent the formation of ER-positive tumors in women at high risk of breast cancer, these agents do not prevent ER-negative and triple-negative breast cancers. A substantial unmet need remains to prevent formation of ER-negative and triple negative breast cancers, which are often highly aggressive and associated with poorer survival. This study opens the door to the future research to evaluate the possibility of using RXR agonists, like IRX4204, to prevent these cancers.”

Martin E. Sanders, M.D., Chief Executive Officer of Io Therapeutics stated “IRX4204 is a clinical stage compound which was invented by Vidyasagar, Ph.D., Chief Science Officer at Io Therapeutics. IRX4204 more potently and more selectively activates RXR than earlier generation RXR agonists. It has demonstrated an excellent safety profile in clinical trials in over 100 patients. IRX4204 has a safety profile that should allow it to be suitable as an agent for chronic treatment to effect prevention of triple negative breast cancers. This outcome would provide major benefit to millions of women now and in the future, who are at risk over the course of their lifetimes for the development of aggressive, poorly treatable estrogen receptor-negative or triple-negative breast cancers.”

About Io Therapeutics: Io Therapeutics, Inc. is a privately held company headquartered in Spring, Texas. More information on Io Therapeutics and its product development programs is available on the company’s web site: www.io-therapeutics.com

Forward Looking Statements: This new release contains "forward-looking statements" within the meaning of the safe harbor provisions of the United States Private Securities Litigation Reform Act of 1995.

Contact: info@io-therapeutics.com