Accent Therapeutics Announces First Patient Dosed in Phase 1/2 Trial of ATX-559 and Chief Scientific Officer Transition

On December 11, 2024 Accent Therapeutics, a clinical-stage biopharmaceutical company pioneering novel, targeted, small molecule cancer therapeutics, reported that the first patient has been dosed in the Phase 1/2 clinical trial evaluating the safety and tolerability of ATX-559, a first-in-class oral DHX9 inhibitor (Press release, Accent Therapeutics, DEC 11, 2024, View Source [SID1234649057]). The company also announced the retirement of Robert A. Copeland, Ph.D., Co-Founder, President, and Chief Scientific Officer (CSO), and the promotion of Serena Silver, Ph.D., to CSO.

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ATX-559 is a first-in-class potent and selective inhibitor of DHX9, a novel and previously undrugged RNA and DNA/RNA helicase, which is reported to play a critical role in tumors with high levels of replication stress (including breast, ovarian, colorectal, endometrial, gastric, and others), representing large patient populations with significant unmet medical need. The ATX-559 Phase 1/2 study (NCT06625515) is designed to evaluate the molecule’s safety profile at multiple dose levels, assessing tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy. The trial is enrolling solid tumor patients, with a particular focus on patients with BRCA1- or BRCA2-deficient breast cancer and patients with MSI-H and/or dMMR solid tumors (including certain patients with colorectal, endometrial, gastric, and other cancers). The advancement of ATX-559 into the clinic, followed closely by the KIF18A program, which is expected to enter the clinic in 1H 2025, marks a critical milestone for the company to advance potentially transformative therapies for cancer patients.

"We are thrilled to begin evaluating ATX-559 in cancer patients. 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. Likewise, about half of patients with MSI-H/dMMR colorectal cancer patients will need additional treatments following PD-(L)1 inhibitors," said Jason Sager, M.D., Chief Medical Officer of Accent Therapeutics. "With ATX-559 entering clinical trials and Accent’s KIF18A inhibitor poised to begin Phase 1 studies, we are well-positioned to translate our rigorous scientific research into the development of multiple new medicines for treating cancer. These programs represent years of the Accent Therapeutics team’s pioneering research and scientific rigor as we seek to identify meaningful new treatment options for patients who face these challenging malignancies."

Effective January 1, 2025, Serena Silver, Ph.D., will be promoted to the position of Chief Scientific Officer. Dr. Silver joined Accent in September 2022 as Vice President of Biology, bringing a breadth of experience across target discovery, drug discovery, and translational research. Prior to joining Accent, Dr. Silver was Vice President of Discovery Biology and Technologies at Fulcrum Therapeutics, where she led scientific teams to develop and deploy new assay modalities and complex cellular models of disease to identify targets and discover therapeutics for rare diseases. Previously, Dr. Silver led the Molecular Pharmacology group at Novartis Oncology, the Target ID and Validation team at Sanofi Oncology, and worked at the forefront of functional genomics screening technology at the Broad Institute. Dr. Silver holds a Ph.D. in Biology from the Massachusetts Institute of Technology and completed a postdoctoral fellowship at Harvard Medical School.

"We are delighted to promote Dr. Silver to the position of Chief Scientific Officer. Her exceptional expertise in cancer biology and strategic vision make her the ideal scientific leader as we continue to advance the science underlying our novel DHX9 and KIF18A programs in our mission to bring innovative treatments to patients," said Shakti Narayan, Ph.D., J.D., Chief Executive Officer of Accent Therapeutics. "Since co-founding Accent in 2017 and serving as President and CSO, Dr. Copeland’s visionary leadership has been instrumental in shaping our scientific direction. We want to thank Bob for his invaluable contributions to Accent and wish him the best for the future."

Dr. Copeland has served as Co-Founder, President, and Chief Scientific Officer at Accent since the company’s founding in 2017. He was formerly President of Research and CSO of Epizyme, Inc. and before that, Vice President of Cancer Biology in the Oncology Center of Excellence in Drug Discovery at GlaxoSmithKline. He has contributed to drug discovery and development efforts leading to 20 investigational new drugs entering human clinical trials. He is a member of the editorial boards of Molecular Cancer Therapeutics (AACR) (Free AACR Whitepaper) and ACS Medicinal Chemistry Letters. He also serves on multiple biotechnology scientific advisory boards. Dr. Copeland received his doctorate in chemistry from Princeton University and was the Chaim Weizmann Fellow at the California Institute of Technology. He was elected a Fellow of the American Association for the Advancement of Science (AAAS) and of the Royal Society of Chemistry.

"I am honored to step into the role of CSO at Accent," said Dr. Silver. "Our team has made significant strides towards advancing transformative medicines for cancer patients, and I am excited to lead our scientific efforts as we enter the clinic. I look forward to leveraging our exceptional talent and rigorous scientific foundation to continue translating our discoveries into impactful therapies for patients."

In addition to ATX-559, Accent anticipates initiating a Phase 1 trial in 1H 2025 for its second program targeting KIF18A in chromosomally instable tumors. The transition to a clinical-stage company marks a meaningful inflection point as Accent continues to advance its pipeline of innovative cancer therapies.

About ATX-559

ATX-559 is a first-in-class potent and selective inhibitor of DHX9, a novel and previously undrugged RNA and DNA/RNA helicase, which is reported to play a critical role in tumors with high levels of replication stress (including breast, ovarian, colorectal, endometrial, gastric, and others), representing large patient populations with significant unmet medical need. DHX9 has been reported to play important roles in replication, transcription, translation, RNA splicing, RNA processing, and maintenance of genomic stability. In addition to exploiting key tumor vulnerabilities in DNA repair deficient backgrounds (e.g., BRCA) and hyper-mutated states (e.g., MSI-H/dMMR), Accent is exploring the sensitivity of other tumor types to DHX9 inhibition, and the potential to combine DHX9 inhibitors with other cancer treatments to maximize its full potential for helping patients. Therefore, this enzyme represents a compelling novel oncology target. Accent retains full worldwide rights to ATX-559, currently being evaluated in a Phase 1/2 clinical trial (NCT06625515), and the DHX9 program.

About KIF18A

Accent’s second lead program is a potential best-in-class inhibitor for KIF18A which may address a large patient population across several cancer indications, including ovarian and triple negative breast cancer (TNBC). KIF18A is a mitotic kinesin motor protein critical for cell division in select tumors with chromosomal instability, but not in healthy cells. KIF18A inhibitor treatment results in rapid cell death for cancers with an abnormal number of chromosomes (aneuploid) in vitro and in vivo, while cells with normal numbers of chromosomes (euploid) are unaffected. Accent retains full worldwide rights to the KIF18A program, which is anticipated to enter the clinic in 1H 2025.