Rgenta Therapeutics Presents Preclinical Data Demonstrating Anti-Tumor Activity of Oral Small Molecule MYB Inhibitor, RGT-61159, in Multiple Models of AML at the 66th American Society of Hematology (ASH) Annual Meeting

Data provide support for planned expanded clinical development of best-in-class RGT-61159 in MYB-dependent hematologic cancers, including AML

Potent anti-tumor activity observed, providing further evidence for the promising mechanism of RGT-61159 as the company advances the drug candidate in its ongoing Phase 1a/b clinical trial in patients with relapsed or refractory ACC or CRC

WOBURN, Mass., Dec. 9, 2024 /PRNewswire/ -- Rgenta Therapeutics, a clinical-stage biotechnology company pioneering the development of a new class of oral small molecules targeting RNA for oncology and neurological disorders, announced today the presentation of preclinical data demonstrating anti-tumor activity of RGT-61159, a potent, selective oral small molecule inhibitor of MYB, a master oncogene in human malignancies.  The data, which are being presented at the 66th American Society of Hematology Annual Meeting and Exposition being held December 7-10, 2024, in San Diego, CA, support the development of RGT-61159 as a potential treatment for acute myeloid leukemia (AML).

"As demonstrated by the data being presented at ASH, RGT-61159 leads to the elimination of MYB RNA and protein in cancer cells and results in significant anti-tumor activity," said Simon Xi, Ph.D., co-founder and chief executive officer of Rgenta. "Importantly, RGT-61159 is active in a range of AML models harboring the most prevalent genetic alterations found in patients that often lead to resistance to current treatments. These data support our plans to extend our clinical development of RGT-61159 beyond our existing programs in solid tumors, adenoid cystic carcinoma (ACC) and colorectal cancer (CRC), and into hematologic malignancies such as AML."

RGT-61159 is a potent, selective oral small molecule inhibitor of the MYB oncogene that functions by inducing the inclusion of a cryptic exon into MYB RNA transcripts, resulting in the activation of the nonsense mediated decay pathway and promoting MYB mRNA depletion and thus, MYB protein degradation. The data presented at ASH demonstrate that RGT-61159 potently eliminates MYB RNA and protein in a dose-dependent manner in AML cancer cell lines. As a single agent, RGT-61159 showed significant anti-tumor activity in several AML cell line-derived xenograft (CDX) models that harbor the most prevalent genetic alterations found in patients. In addition, RGT-61159 driven MYB inhibition led to a robust, dose-dependent increase in the differentiation markers CD11b and CD14 on the surface of THP-1 AML cells and the reduction of master oncogenes such as MYC and BCL2 across a broad panel of AML cell lines, providing a strong rationale for its development as a treatment for patients with AML.

"Genomic analyses of different AML cell lines treated with RGT-61159 shed further light on key oncogenes including BCL2 and MYC that are significantly regulated by MYB inhibition and further demonstrate RGT-61159's anti-tumor activity of leukemic cells is driven by inhibition of MYB signaling," said Travis Wager, Ph.D., co-founder, president and chief scientific officer. "These data also confirm the role of MYB as a convergent dependency across AML tumors and highlight the potential of RGT-61159, a best-in-class MYB inhibitor, as a novel therapeutic approach to address this malignancy."

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 production, which has the potential to induce cell death of the cancer cells overexpressing 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 leukemias (AML), T-cell acute lymphoblastic leukemias (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 and 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).

About Acute Myeloid Leukemia (AML)
AML is a blood cancer that starts in the bone marrow, begins to make large numbers of abnormal cells, is characteristically fast growing, and moves quickly into the blood. AML is the most common type of acute leukemia in adults, and it accounts for about 10% of all new blood cancers each year. In the United States, there are about 20,000 new cases of AML per year. The average age of people diagnosed with AML is 68 years old, and while it is uncommon in people under 45, it can occur in adolescents and children. While complete remission can be achieved in up to 70% of patients with newly diagnosed AML, prognosis remains poor with only approximately 32% of patients that remain alive 5 years after diagnosis. Allogeneic hematopoietic cell transplantation (HCT) remains the only potentially curative strategy for most patients. Up to 40% of patients relapse after allogeneic HCT, and 5-year overall survival (OS) rates for these patients are low,  approximately 30–40%.

About Rgenta Therapeutics
Rgenta Therapeutics is a clinical stage biotechnology company developing a pipeline of oral RNA-targeting small molecule medicines with an initial focus on oncology and neurological disorders. Our proprietary platform mines the massive genomics data to identify targetable RNA processing events and design small-molecule glues to modulate the interactions among the spliceosome, regulatory proteins, and RNAs. Our lead programs and unique approach are unlocking the therapeutic potential of historically undruggable targets in human diseases. Learn more at: http://www.rgentatx.com.

Contacts
Investors:
Sylvia Wheeler
Wheelhouse Life Science Advisors
[email protected]

Elizabeth Wolffe, Ph.D.
Wheelhouse Life Science Advisors
[email protected]

Media
Aljanae Reynolds
Wheelhouse Life Science Advisors
[email protected]

SOURCE Rgenta Therapeutics