On May 21, 2026 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 positive preliminary data from its ongoing Phase 1a/b clinical trial of RGT-61159, an oral small molecule targeting MYB, in patients with advanced, relapsed or refractory adenoid cystic carcinoma (ACC) or colorectal cancer (CRC) at the 2026 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Meeting being held this week in Chicago. The early data supports promising and durable anti-tumor activity in advanced ACC, demonstrated MYB target engagement and an attractive, well-tolerated safety profile at RP2Ds for once-daily oral administration of RGT-61159.
Schedule your 30 min Free 1stOncology Demo!
Discover why more than 1,500 members use 1stOncology™ to excel in:
Early/Late Stage Pipeline Development - Target Scouting - Clinical Biomarkers - Indication Selection & Expansion - BD&L Contacts - Conference Reports - Combinatorial Drug Settings - Companion Diagnostics - Drug Repositioning - First-in-class Analysis - Competitive Analysis - Deals & Licensing
Schedule Your 30 min Free Demo!
"While still early, these data are encouraging and supportive of the potential of RGT-61159 as a promising anti-tumor agent with a favorable safety profile in a particularly aggressive form of cancer, ACC," said Dr. Ho, M.D., Chief of Head and Neck Medical Oncology at Memorial Sloan Kettering Cancer Center. "Further, these data demonstrate that RGT-61159 knockdown of MYB protein, an oncogene that drives cancer progression, is a promising approach for treating cancers that over-express MYB. I look forward to the final results from this study and seeing the continued maturity of efficacy, safety and durability data."
Simon Xi, Ph.D., co-founder and chief executive officer of Rgenta added, "These are the first clinical data generated for RGT-61159 and we are pleased with the early results showing an impressive disease control rate and anti-tumor activity in ACC that deepens over time. In addition, RGT-61159 has demonstrated a favorable, well-tolerated safety profile. We look forward to initially advancing RGT-61159 into further development in ACC, an indication with a high unmet need, and plan to expand into other MYB-driven cancers in the future."
Rgenta’s Phase 1a/b clinical trial of RGT-61159 is a multi-center, open-label dose escalation and expansion study in patients with advanced relapsed or refractory ACC or CRC. The Phase 1a/b study is evaluating 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).
Preliminary data from the initial patients in the trial showed clinically meaningful disease control of 84.6% in 39 evaluable patients, with 3 patients achieving partial response according to RECIST criteria (2 confirmed). Responses continued to deepen with longer treatment duration. Patients with partial responses have remained on study for a mean of 8.2 months, while all ongoing patients across the trial have a mean on-study duration of 7.3 months. RGT-61159 was well tolerated with the most common adverse events being fatigue, anemia, diarrhea and nausea.
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 oncogenic MYB protein production, which has the potential to inhibit proliferation or induce cell death of cancer cells that overexpress MYB protein. MYB acts as a master regulator of cell proliferation 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.
About Adenoid Cystic Carcinoma (ACC)
It is estimated that approximately 200,000 people are living with ACC throughout the world including 11,000 in the US. While it is a rare cancer, ACC is the second most common cancer type arising in the salivary gland and is an aggressive malignancy with a tendency to infiltrate surrounding nerves and metastasize to distant sites. Overactivation of the MYB oncogene has been described as a hallmark of ACC and is noted in over 90% of ACC. Treatment for ACC is extremely challenging and may include surgery and/or radiation, which often fails to control local tumor recurrence and distant metastases. There are no effective targeted therapies available for patients with recurrent and/or metastatic disease. There is thus an unmet medical need for new therapeutic targets and treatment strategies for patients with this fatal cancer.
About Colorectal Cancer (CRC)
CRC is the third most prevalent cancer and the second leading cause of cancer-related mortality worldwide. According to the World Health Organization, in 2022, more than 1.9 million cases of CRC were diagnosed. Despite the improved early detection of CRC and the recent success of targeted therapeutics, approximately 15%-30% of patients present with metastases and 20%-50% of patients with initially localized disease will develop metastases. Patients with relapsed or refractory CRC who have exhausted all the available standard of care therapy options, have a very poor prognosis. MYB is significantly overexpressed in 80-85% of CRC and has been frequently found to be a predictive biomarker of tumor aggressiveness and poor prognosis. Developing novel therapies to treat patients with metastatic CRC remains a major unmet medical need.
(Press release, Rgenta Therapeutics, MAY 21, 2026, View Source [SID1234665991])