TransCode Advances TTX-MC138 in Phase 1a Cancer Trial

Boston, Massachusetts, U.S., September 28, 2026

TTX-MC138 Shows Durable Disease Control

In the updated analysis, 71.4% of efficacy-evaluable patients achieved stable disease as their best overall response based on investigator assessment. The disease-control rate was 57.1% at three months and 35.7% at six months, demonstrating that disease stabilization was observed beyond an initial treatment assessment in a subset of patients. Three of the 14 efficacy-evaluable patients remained progression-free at nine and 12 months, according to the company. The findings are notable because the Phase 1a study enrolled patients with advanced and heavily pretreated solid tumors, a population in which treatment options can be limited and disease progression can occur despite multiple prior therapies. However, the study was primarily designed as a first-in-human dose-escalation trial, meaning the small efficacy-evaluable population limits the ability to draw definitive conclusions about clinical effectiveness. The reported disease stabilization therefore represents an early clinical signal requiring confirmation in larger and more focused studies. TransCode also conducted a post-hoc Growth Modulation Index (GMI) analysis comparing progression-free survival on TTX-MC138 with the patient’s most recent prior systemic anticancer treatment. Six of 15 evaluable patients, or 40%, had a GMI greater than 1.3, a threshold commonly used in oncology research to indicate a potentially meaningful improvement in treatment duration. Because this was a post-hoc analysis, the result should be considered exploratory.

RNA Therapeutic Targets Metastatic Cancer Biology

TTX-MC138 is an investigational therapeutic designed to inhibit microRNA-10b, or miR-10b. TransCode identifies miR-10b as a molecular driver associated with the emergence and progression of metastatic disease. The candidate is part of the company’s broader RNA-based immuno-oncology platform, with development focused on advanced cancers and tumors expressing the relevant biomarker. The Phase 1a program previously established a recommended Phase 2 dose of 4.8 mg/kg and met its primary safety objective. Earlier results showed no dose-limiting toxicities across the evaluated dose levels. The June 2026 analysis also reported that nine of 14 evaluable patients had stable disease lasting six months, providing an earlier indication of potentially durable disease control. The September update adds longer follow-up to that earlier dataset. TransCode reported that a total of 98 doses had been administered by the September 1 cutoff and that treatment exceeding one year had been well tolerated in patients who remained on therapy. No dose-limiting toxicities were reported, including at the highest evaluated dose of 4.8 mg/kg, and no treatment-emergent adverse events resulted in treatment discontinuation.

TransCode Moves Toward Further Clinical Evaluation

The updated findings support TransCode’s plans to continue evaluating safety, pharmacokinetics, pharmacodynamics and antitumor activity while exploring dose-expansion strategies in selected cancers and molecularly defined patient populations. The company has already initiated a Phase 2a study in patients with circulating tumor DNA-positive colorectal cancer, narrowing development toward a defined patient population.

For cGxP.wire readers, the program is particularly relevant because it combines RNA therapeutics, molecular oncology and biomarker-guided cancer treatment. The continued disease stabilization reported in the Phase 1a follow-up provides additional clinical data for TTX-MC138, while the absence of dose-limiting toxicities supports continued investigation. Nevertheless, TTX-MC138 remains investigational, and its safety and efficacy have not been established by the FDA or another regulatory agency. Larger, disease-specific studies will be needed to determine whether the early signals translate into meaningful clinical benefit.

Source: TransCode Therapeutics press release