WOBURN, Massachusetts, May 21, 2026
Rgenta Therapeutics announced positive preliminary results from its ongoing Phase 1a/b clinical trial evaluating RGT-61159, an investigational oral small molecule targeting the oncogene MYB, in patients with advanced adenoid cystic carcinoma (ACC) and colorectal cancer (CRC). The data, presented at the ASCO Annual Meeting 2026 in Chicago, demonstrated encouraging anti-tumor activity, strong disease control, and a favorable safety profile in heavily pretreated patients with relapsed or refractory cancers. Investigators reported that patients treated at or below the recommended Phase 2 dose achieved an 84.6% disease control rate, with multiple partial responses and evidence that tumor responses continued to deepen over time. The findings position RGT-61159 as one of the emerging RNA-targeting oncology candidates designed to attack previously “undruggable” cancer-driving transcription factors.
Early Clinical Data Show Durable Anti-Tumor Activity in ACC
The ongoing multi-center Phase 1a/b study is evaluating the safety, tolerability, pharmacokinetics, target engagement, and preliminary efficacy of RGT-61159 in patients with advanced ACC or CRC who have exhausted standard treatment options. Among 39 evaluable patients treated at or below the recommended Phase 2 dose, investigators observed 33 patients achieving disease control, including three partial responses according to RECIST criteria, with two responses already confirmed and one awaiting confirmation.
Researchers also noted that anti-tumor responses appeared to deepen with longer treatment duration, suggesting the therapy may produce increasingly durable benefit over time. Patients who achieved partial responses remained on treatment for an average of 8.2 months, while ongoing participants across the broader study maintained a mean treatment duration of 7.3 months. Investigators highlighted the significance of these findings in adenoid cystic carcinoma, a rare and aggressive cancer with extremely limited therapeutic options and no approved targeted treatments for recurrent or metastatic disease.
RNA-Targeting Strategy Aims to Block MYB Cancer Driver
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RGT-61159 is designed to specifically target and modulate RNA splicing associated with the MYB transcription factor, a major oncogenic driver implicated in multiple cancers. The therapy works by disrupting MYB protein production, which may inhibit cancer cell proliferation and trigger tumor cell death in MYB-overexpressing tumors. MYB overactivation is considered a hallmark feature in more than 90% of ACC tumors and is also frequently overexpressed in colorectal cancer, leukemia, small cell lung cancer, and breast cancer. Unlike conventional therapies that directly target proteins, Rgenta’s approach focuses on manipulating RNA processing using oral small molecules capable of modulating spliceosome activity and regulatory protein interactions. Company executives stated that the early data validate the broader potential of RNA-targeting therapies as a new class of precision oncology medicines capable of addressing difficult-to-treat cancers that have historically lacked effective molecular targets.
Safety findings from the study were also encouraging. RGT-61159 was generally well tolerated at the recommended Phase 2 dose, with the most common adverse events including fatigue, anemia, diarrhea, and nausea. Researchers additionally reported clinically relevant dose-dependent reductions in MYB mRNA levels, confirming direct biological target engagement. Pharmacokinetic data demonstrated a half-life supportive of convenient once-daily oral dosing, an important potential advantage for long-term treatment management in cancer patients.
ACC Represents Major Unmet Need in Precision Oncology
Adenoid cystic carcinoma remains one of the most challenging rare cancers to treat due to its tendency for local recurrence, nerve invasion, and distant metastasis. Although considered rare, approximately 200,000 patients worldwide are estimated to be living with ACC, including roughly 11,000 patients in the United States. Standard treatment approaches such as surgery and radiation often fail to prevent disease progression, while metastatic and recurrent ACC currently lack effective targeted therapies. Similarly, metastatic colorectal cancer continues to represent a major global health burden despite recent advances in targeted medicine, with patients who progress after standard therapies facing poor survival outcomes.
Rgenta executives indicated the company plans to initially prioritize further development of RGT-61159 in ACC before potentially expanding into additional MYB-driven cancers. The company believes its proprietary RNA-targeting platform may unlock entirely new therapeutic opportunities across oncology and neurological diseases by enabling precise control over disease-related RNA processing pathways.
Source: Rgenta Therapeutics press release
