• ~67% eye preservation rate (6 of 9 enucleation patients) with darovasertib monotherapy neoadjuvant uveal melanoma treatment
• Median tumor shrinkage (maximum volume change) of ~39% after 6 months
• Clinical data on additional enucleation patients and with further follow-up from the abstract-summary cut-off date will be presented at ASCO 2024
• Darovasertib was generally well tolerated with no drug-related serious adverse events
• Oral presentation at ASCO 2024 scheduled for Monday, June 3, 2024 at 9:51am CDT

SOUTH SAN FRANCISCO, Calif., May 23, 2024 /PRNewswire/ -- IDEAYA Biosciences, Inc. (Nasdaq: IDYA), a precision medicine oncology company committed to the discovery and development of targeted therapeutics, today announced the publication of the abstract for an oral presentation of preliminary clinical results from its investigator-sponsored Phase 2 trial of darovasertib, a first-in-class oral, small molecular inhibitor of protein kinase C (PKC), as neoadjuvant/adjuvant treatment in uveal melanoma (UM) at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting.

Anthony Joshua, MBBS, PhD, FRACP, Head Department of Medical Oncology, Kinghorn Cancer Centre, St. Vincent's Hospital in Sydney, who is the leading principal investigator of the Phase 2 study, will present the clinical data from the Phase 2 Neoadjuvant / Adjuvant trial of Darovasertib in Ocular Melanoma" (NADOM) study. Details of the presentation are as follows:

• Session: Melanoma / Skin Cancers
• Title: A Phase 2 Safety and Efficacy Study of Neoadjuvant/Adjuvant Darovasertib for Localized Ocular Melanoma
• Date: Monday, June 3, 2024, at 9:51 AM CDT

In summary, 15 patients planned for enucleation with localized UM were treated with darovasertib 300mg twice daily. An initial safety cohort of 3 patients were treated for one month, and the remaining 12 patients were treated in an expansion cohort for up to six months as neoadjuvant treatment prior to their primary intervention (enucleation, plaque brachytherapy or external beam radiotherapy (EBRT)) across three Australian centers.

As of the database lock, 11 patients had completed primary treatment, four remained on neoadjuvant treatment, and six patients received adjuvant darovasertib after primary treatment of their UM with three patients completing the planned six months. At that time, approximately 67% (6 of 9 patients) had confirmed Eye Saved (i.e., converted to plaque brachytherapy or EBRT). Median tumor shrinkage (maximum volume change) was approximately 39% after six months.

The darovasertib monotherapy neoadjuvant treatment was generally well tolerated. Drug-related adverse events (AEs) were predominantly Grade 1 or Grade 2. Thirteen percent of patients reported at least one drug-related Grade 3 adverse event and no drug-related serious adverse events were observed.

Additional patients and further follow up from the abstract summary cut-off date will be presented on the June 3, 2024, ASCO oral presentation. A copy of the ASCO oral presentation will be available at approximately 10:00am CDT at its Investor Relations portal under "Events" (https://ir.ideayabio.com/) on the day of the presentation.

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 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 the content and timing of the ASCO oral presentation. Such forward-looking statements involve substantial risks and uncertainties that could cause IDEAYA's preclinical and clinical development programs, future results, performance or achievements to differ significantly from those expressed or implied by the forward-looking statements. Such risks and uncertainties include, among others, the uncertainties inherent in the drug development process, including IDEAYA's programs' early stage of development, the process of designing and conducting preclinical and clinical trials, the regulatory approval processes, the timing of regulatory filings, the challenges associated with manufacturing drug products, IDEAYA's ability to successfully establish, protect and defend its intellectual property, and other matters that could affect the sufficiency of existing cash to fund operations. 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 dated February 20, 2024 and any current and periodic reports filed with the U.S. Securities and Exchange Commission.

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