FoRx Therapeutics presents preclinical data on FORX-428, a PARG inhibitor in Phase 1 development for solid tumours, at ACS Spring 2026

FoRx Therapeutics has presented preclinical data on its PARG inhibitor FORX-428 at the American Chemical Society Spring 2026 meeting, outlining its activity across multiple solid tumour models and positioning the programme within the DNA damage response (DDR) field.

The data include the first public disclosure of the compound’s molecular structure and discovery process, alongside results from in vitro and in vivo studies. According to the company, FORX-428 demonstrated high potency across a range of tumour cell lines, including models resistant to PARP inhibitors.

PARG is emerging as a potential next-generation target within the DDR pathway, particularly for cancers that no longer respond to PARP inhibition. While PARP inhibitors have been used in oncology for more than a decade, resistance remains a major challenge, creating demand for alternative approaches targeting DNA repair mechanisms.

In preclinical testing, FORX-428 showed anti-tumour activity in three key settings: homologous recombination-deficient tumours, PARP inhibitor-resistant cancers and tumours with high replication stress. The company reported broader activity compared with a reference compound, which was primarily active in more sensitive models.

FoRx also presented data suggesting favourable pharmacokinetics and selectivity, as well as a safety profile that supported progression into clinical testing. The compound is currently being evaluated in an open-label Phase 1 trial in patients with advanced solid tumours who have exhausted standard treatment options.

Tarig Bashir, chief executive officer of FoRx Therapeutics, said: “The robust preclinical data presented at ACS Spring 2026 support FORX-428’s best-in-class potential and why we believe it has the potential to meaningfully improve treatment options for patients.” He added that the Phase 1 study is progressing towards an initial data readout expected in mid-2026.

The trial, which began recruitment in 2025, is assessing safety, tolerability, pharmacokinetics and early signs of efficacy across multiple cancer types. No clinical data have been disclosed to date.

The presentation highlights continued interest in expanding the DDR toolkit beyond PARP inhibitors, particularly in resistant disease. However, as the findings are based on preclinical data, the relevance of the results will depend on whether the compound demonstrates similar activity and tolerability in patients.