FoRx Therapeutics has dosed the first patient in a Phase 1 trial of FORX-428, an oral PARG inhibitor, in patients with advanced solid tumors. Initial data from this open-label U.S. study are anticipated by mid-2026, focusing on safety, tolerability, pharmacokinetics, and preliminary efficacy in patients who have exhausted standard treatment options.
This first-in-human trial marks a significant step in FoRx’s strategy to capitalize on the clinical success of PARP inhibitors by targeting a next-generation DNA damage response (DDR) pathway. The company is betting that PARG inhibition offers a viable treatment avenue for patients whose cancers are resistant to existing PARP inhibitors, a patient segment with growing unmet need as PARP inhibitor use expands. This trial also highlights FoRx’s broader bet on the DDR pathway beyond PARP.
Preclinical data suggest that FORX-428 exhibits strong anti-tumor activity and a favorable safety profile in various solid tumor models. FoRx is emphasizing the “best-in-class” potential of its molecule, likely aiming to attract further investment and establish early differentiation in a competitive field. The speed from IND clearance in June 2025 to the first patient dosed in August underscores operational efficiency and collaborative effectiveness between the company and the START Midwest research site.
For research sites, the emergence of PARG inhibitors represents a new avenue for patient recruitment and participation in cutting-edge oncology trials. For pharmaceutical developers, FoRx’s trial will be a key indicator of the broader viability of the PARG pathway. For regulators, this trial represents another test of DDR-targeting agents and how they may expand the clinical utility of precision oncology.
Several critical questions remain. The Phase 1 data will need to confirm the preclinical safety and efficacy signals in humans. The durability of response and identification of optimal tumor types for PARG inhibition will be essential for later-stage development. FoRx will need to navigate a complex regulatory landscape, potentially including biomarker-driven patient selection and combination therapy strategies, as it advances FORX-428 through the clinical pipeline.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
