The Rett Syndrome Research Trust Funds Herophilus’ Rett Syndrome Lead Candidate Studies

The Rett Syndrome Research Trust Funds Herophilus’ Rett Syndrome Lead Candidate Studies

The Rett Syndrome Research Trust Funds Herophilus’ Rett Syndrome Lead Candidate Studies

SAN FRANCISCO–(BUSINESS WIRE)–#drugdiscovery–Herophilus announced today that in vivo studies underway of its lead candidate HRP-12975 are funded in part by the Rett Syndrome Research Trust (RSRT). HRP-12975 is the first small molecule therapy for Rett Syndrome with the potential to reverse the root cause of the disease, MECP2 deficiency.

HRP-12975 is the first novel disease-modifying chemical entity discovered with any brain organoid discovery platform and thus represents an industry first and validation for the approach of human-led in vitro experimental drug discovery. HRP-12975 causes reactivation of the MECP2 gene on the silenced X chromosome in brain cells of Rett patients. This strategy avoids the risk of MECP2 overexpression inherent with many proposed gene therapies. MECP2 overexpression is known to cause MECP2 duplication syndrome, an extremely severe and often fatal neurodevelopmental disease.

HRP-12975 was discovered by screening a highly curated chemical library of 12,000 target-annotated compounds for MeCP2 reactivation in neurons and astrocytes using 3D Rett patient organoid models on Herophilus’ discovery platform. With the support of RSRT, Herophilus is now generating efficacy and safety data of HRP-12975 using genetic mouse models of Rett Syndrome.

We are thrilled to support the next phase of therapeutic development for molecules identified from Herophilus’ novel approach to discovering x-reactivators using patient-derived brain organoids. Reactivation of the silent MECP2 gene is an important therapeutic strategy for us and we are encouraged by Herophilus’ progress,” said Monica Coenraads, CEO of the Rett Syndrome Research Trust.

The Rett Syndrome Research Trust has been instrumental in catalyzing therapeutics development for a devastating, currently incurable, neurodevelopmental disease, and we are grateful for the support and recognition of the potential of our program,” said Saul Kato, PhD, CEO and co-founder of Herophilus.

Herophilus has worked with the RSRT since 2018. As a foundation for Herophilus’ Rett Syndrome discovery program, they collaborated on the most comprehensive biobank of inducible pluripotent stem cell lines and organoids derived from Rett patients.

About the Rett Syndrome Research Trust

RSRT is a nonprofit organization singularly focused on achieving a cure for Rett syndrome and related disorders caused by defects in the MECP2 gene. Since its founding in 2008, RSRT has awarded $64 million, more than any other Rett organization in the world, to leading scientists pursuing targeted research on Rett. RSRT funds and spearheads global scientific and clinical activities advancing the most promising curative approaches. To date, every biopharmaceutical company pursuing a cure for Rett syndrome is doing so because they leveraged discoveries and resources incubated with RSRT funding.

About Herophilus

Herophilus is a San Francisco-based neurotherapeutics company focused on curing complex brain diseases. The company’s platform combines brain organoid science, systems neuroscience approaches, robotic automation, and advanced machine learning techniques to scale the ability to discover novel drugs for complex neurological and psychiatric diseases. In an industry-first approach, the company employs multi-modal phenotypic screening to discover characterizations of diseases never before achievable. These “deep phenotypes” are exploited to identify novel therapeutic targets and drug treatments for disorders for which current discovery techniques have proved least successful, including neurodevelopmental, psychiatric and neurodegenerative diseases. To learn more, visit


Herophilus – Media Contact

Jessica Sims