IDEAYA Announces First Patient Dosed in Phase 1 Clinical Trial for IDE161 as Potential First-in-Class PARG Inhibitor Targeting HRD Solid Tumors

• Evaluating IDE161 in patients having solid tumors with HRD, with expansion focus in ER+ / Her2- breast cancer with HRD, representing approximately 10% to 14% of breast cancer
• Dose escalation in patients having HRD solid tumors, with initial dose at one-half of the projected human efficacious dose, based on preclinical efficacy and tolerability studies
• IDE161 is a potent, selective, small-molecule inhibitor of PARG – a mechanistically-differentiated target in the clinically-validated DNA damage repair (DDR) pathway
• AACR presentation profiling IDE161 on Wednesday, April 19, 2023

SOUTH SAN FRANCISCO, Calif., April 19, 2023 /PRNewswire/ -- IDEAYA Biosciences, Inc. (NASDAQ: IDYA), a precision medicine oncology company committed to the discovery and development of targeted therapeutics, announced achievement of First-Patient-In in the Phase 1 clinical trial evaluating IDE161 (NCT 05787587) and release of a poster presentation profiling IDE161 at AACR 2023. IDE161 is a potent, selective, small-molecule inhibitor of PARG, a novel and mechanistically-differentiated target in the same clinically validated pathway as poly (ADP-ribose) polymerase (PARP).

“We are excited to clinically investigate IDE161 as a potential first-in-class synthetic lethality treatment for cancer patients with homologous recombination deficiencies (HRD). We believe IDE161 may be impactful for ER+ / Her2- breast cancer patients with HRD, as well as for patients having ovarian cancer and other solid tumors with HRD, for whom current treatment options are limited,” said Dr. Darrin M. Beaupre, M.D., Ph.D., Chief Medical Officer, IDEAYA Biosciences. “Based on its preclinical tolerability profile, IDE161 may also be suitable for evaluation with several distinct classes of combination agents, providing multiple paths to demonstrate patient benefit in these populations,” continued Dr. Beaupre.

Dr. Timothy Yap, M.D., Ph.D., Associate Professor of Investigational Cancer Therapeutics at The University of Texas MD Anderson Cancer Center in Houston, the site which dosed the first patient, is a leading principal investigator for the Phase 1 clinical trial evaluating IDE161.

IDEAYA’s Phase 1 clinical trial will evaluate the safety, tolerability, pharmacokinetic and pharmacodynamic properties and preliminary efficacy of IDE161 as monotherapy in patients having tumors with homologous recombination deficiency (HRD). The clinical protocol includes dose escalation in solid tumors with HRD. Subject to selection of an expansion dose, the company is planning expansion in cohorts for patients having HRD tumors in breast cancer, ovarian cancer, and a basket of other solid tumors. The breast cancer cohort will focus on estrogen receptor positive (ER+), human epidermal growth factor receptor 2 negative (Her2-) tumors with HRD, which represent approximately 10% to 14% of breast cancer patients.

IDEAYA is planning to present a poster with preclinical data profiling IDE161 at the 2023 Annual Meeting of the American Association for Cancer Research (AACR) on Wednesday, April 19, 2023:

• Abstract 6093: “IDE161, a potential first-in-class clinical candidate PARG inhibitor, selectively targets Homologous-Recombination-Deficient and PARP inhibitor resistant breast and ovarian tumors” (Abed, M. et al.)
• Date/Time: Wednesday April 19, 2023 at 9:00 am - 12:30 pm ET
• Session / Location: Molecular/Cellular Biology and Genetics, Targeting DNA Damage Response and Novel Pathways; Poster Section 13, Poster Board 1

The IDE161 abstract is available online at http://www.aacr.org in connection with the 2023 Annual Meeting of AACR, and the poster will be available online at https://ir.ideayabio.com/events following the presentation.

An updated corporate presentation, reflecting updates from AACR 2023 for IDE161 (PARG), as well as for IDE397 (MAT2A), co-published with Amgen, and Werner Helicase, co-published with GSK, will also be available on the IDEAYA website at its Investor Relations page: https://ir.ideayabio.com/.

IDEAYA owns or controls all commercial rights in IDE161, subject to certain economic obligations under its exclusive, worldwide license with Cancer Research UK and University of Manchester.

About IDEAYA Biosciences
IDEAYA is a precision medicine oncology company committed to the discovery and development of targeted therapeutics for patient populations selected using molecular diagnostics. IDEAYA’s approach integrates capabilities in identifying and validating translational biomarkers with drug discovery to select patient populations most likely to benefit from its targeted therapies. IDEAYA is applying its early research and drug discovery capabilities to synthetic lethality – which represents an emerging class of precision medicine targets.

Forward-Looking Statements
This press release contains forward-looking statements, including, but not limited to, statements related to (i) possible combination agents with IDE161, (ii) possible expansion cohorts and (iii) the presentation at the 2023 Annual Meeting of AACR. IDEAYA undertakes no obligation to update or revise any forward-looking statements. For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to the business of IDEAYA in general, see IDEAYA’s Annual Report on Form 10-K filed on March 7, 2023 and any current and periodic reports filed with the U.S. Securities and Exchange Commission.

Investor and Media Contact
IDEAYA Biosciences
Paul A. Stone
Senior Vice President and Chief Financial Officer
investor@ideayabio.com

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SOURCE IDEAYA Biosciences, Inc.

Company Codes: NASDAQ-NMS:IDYA