Rgenta Therapeutics Presents Preclinical Data on RGT-61159, a Potent, Selective Oral Small Molecule Inhibitor of MYB, Demonstrating Robust Anti-Tumor Activity in Several Monotherapy Models of AML and Synergistic Activity when Combined with Standard of Care for AML

On April 25, 2025 Rgenta Therapeutics, a clinical-stage biotechnology company pioneering the development of a new class of oral small molecules targeting RNA and RNA regulation for oncology and neurological disorders, reported that preclinical data from its lead program, RGT-61159 were presented at the American Association for Cancer Research (AACR) (Free AACR Whitepaper) 2025 Annual Meeting, which is being held from April 25-30, 2025, in Chicago, IL (Press release, Rgenta Therapeutics, APR 25, 2025, View Source [SID1234652159]). The data demonstrate robust anti-tumor activity of RGT-61159 in several cell-derived xenograft (CDX) models of AML and synergistic benefit when combined with standard of care for AML highlighting the potential of RGT-61159 to treat a broad AML patient population.

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"The data presented at the AACR (Free AACR Whitepaper) meeting highlight the ability of RGT-61159 to reduce levels of both MYB RNA transcripts and correspondingly MYB protein in a dose dependent fashion, which translates to potent killing activity in cells that overexpress MYB," said Travis Wager, Ph.D. co-founder and chief scientific officer. "Importantly, we see robust antitumor activity with RGT-61159 across a range of AML models that carry genetic alterations that are common in patients with AML highlighting its potential to treat a broad AML patient population."

"Using RGT-61159, which specifically acts at the RNA level, we are able to address MYB which has been shown to function as an oncogenic driver in a variety of cancers including AML, colorectal cancer (CRC) and adenoid cystic carcinoma (ACC), and until now, has been a difficult target to drug," said Simon Xi, Ph.D., cofounder and chief executive officer of Rgenta. "Our ongoing Phase 1a/b clinical trial of RGT- 61159 in patients with relapsed or refractory ACC or CRC is advancing well and we look forward to broadening that program and initiating a new Phase 1/2 study of RGT-61159 in adults with AML/high risk myelodysplastic syndromes the second half of 2025."

In a poster titled RGT-61159, Best-in-class Oral Small Molecule Inhibitor of MYB via Selective RNA Splicing Alteration, Synergistic Anti-Tumor Activity When Combined with Standards of Care in Leukemia Disease Models Harboring AML Common Genetic Lesions, data were presented highlighting the close correlation between the elimination of MYB RNA and protein by RGT-61159 and its potent killing activity against leukemia and lymphoma cancer cell lines that over express MYB, demonstrating on-target therapeutic activity of this potent, orally available small molecule. RGT-61159 also inhibited AML cell proliferation and downregulated the expression of master oncogenes controlled by MYB, including MYC, BCL2, FLT3 and IDH1. Data from several CDX models of AML with genetic alterations seen commonly in AML, demonstrated the robust anti-tumor activity of tolerated doses of RGT-61159 and synergistic activity both in vitro and in vivo when administered in combination with agents used in AML standard of care.

About RGT-61159
RGT-61159 is an orally available small molecule designed to specifically modulate splicing of the transcription factor MYB resulting in the inhibition of the oncogenic MYB protein and potential cell death of the cancer cells that overexpress the MYB protein. MYB acts as a master regulator of cell proliferation, self-renewal, and differentiation processes and its aberrant expression has been demonstrated in multiple forms of human cancer including adenoid cystic carcinoma (ACC), acute myeloid leukemia (AML), T-cell acute lymphoblastic leukemia (T-ALL), colorectal cancer (CRC), small cell lung cancer (SCLC) and breast cancer. Rgenta is evaluating RGT-61159 in an ongoing multi-center, open-label Phase 1a/b clinical trial in patients with advanced relapsed or refractory ACC or CRC. The Phase 1a/b study is designed to evaluate safety, tolerability, pharmacokinetics, target engagement and clinical efficacy of RGT-61159 in patients with ACC or CRC. Additional information about the Phase 1a/b clinical trial can be accessed at ClinicalTrials.gov (NCT06462183).