NEW YORK – Accent Therapeutics on Wednesday said it has treated the first cancer patient with the investigational DHX9 inhibitor ATX-559 in a Phase I/II clinical trial.
The study is designed to evaluate the safety, tolerability, and preliminary efficacy of ATX-559 in 100 patients with either BRCA1- or BRCA2-deficient, HER2-negative metastatic breast cancer or solid tumors, including ovarian, colorectal, endometrial, gastric, and other cancers, with DNA mismatch repair deficiencies or high microsatellite instability.
The target that ATX-559 is directed against, DHX9, is a DNA/RNA helicase that Accent believes plays a role in replication, transcription, translation, RNA splicing, RNA processing, and genomic stability maintenance.
"While PARP inhibitors are useful standard treatments for BRCA1- and BRCA2-deficient breast cancer, the majority of patients with metastatic disease will likely need a different treatment within a year or two [and] about half of patients with MSI-H/dMMR colorectal cancer patients will need additional treatments following PD-(L)1 inhibitors," Accent Chief Medical Officer Jason Sager said in a statement.
In addition to the ATX-559 trial, the firm is planning to begin a Phase I trial of an investigational KIF18A inhibitor in the first half of 2025. That trial will enroll patients with chromosomally instable tumors, potentially including triple-negative breast and ovarian cancers.
Earlier this year, Lexington, Massachusetts-based Accent raised $75 million in a Series C funding round, which the firm is using to clinically advance these pipeline agents.
Also on Wednesday, Accent said that President, Cofounder, and CSO Robert Copeland will retire at the end of this year, and that VP of Biology Serena Silver will replace him as CSO.