and the attached Exhibit 99.1 are being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall they be deemed to be incorporated by reference in any filing made by the Company under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Other Events. Underwriting Agreement On June 8, 2026, IDEAYA Biosciences, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with J.P. Morgan Securities LLC, Jefferies LLC, TD Securities (USA) LLC, UBS Securities LLC and Cantor Fitzgerald & Co., as representatives (the “Representatives”) of the several underwriters named therein (collectively, the “Underwriters”), pursuant to which the Company agreed to issue and sell 5,555,556 shares (the “Shares”) of…

Other Events. Clinical Collaboration with Roche in MTAP-Deleted RAS-Mutant Pancreatic Cancer On June 3, 2026, IDEAYA Biosciences, Inc. (the “Company”) announced it has entered into a clinical collaboration with F. Hoffmann-La Roche Ltd (“Roche”) to evaluate the efficacy and safety of IDE892, its investigational, potential best-in-class PRMT5 inhibitor, in combination with Roche’s RG6505, a pan-RAS inhibitor, in patients with pancreatic ductal adenocarcinoma (“PDAC”) that carry an MTAP deletio…

Other Events. On May 5, 2026, IDEAYA Biosciences, Inc. (the “Company”) filed with the Securities and Exchange Commission (the “SEC”) an automatic shelf registration statement on Form S-3ASR (Registration No. 333-295560) (the “New Registration Statement”) to replace its existing automatic shelf registration statement on Form S-3 (Registration No. 333-272936) filed with the SEC on June 26, 2023 (the “Prior Registration Statement”), which was scheduled to expire on June 26, 2026 pursuant to Rule…

and the attached Exhibit 99.1 are being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall they be deemed to be incorporated by reference in any filing made by the Company under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Other Events. On April 8, 2026, IDEAYA Biosciences, Inc. (the “Company”) entered into a clinical collaboration agreement with AstraZeneca plc (“AstraZeneca”) to evaluate the efficacy and safety of IDE849, the Company’s investigational, potential first-in-class DLL3 TOP1 antibody-drug conjugate, in combination with AstraZeneca’s Imfinzi ® (durvalumab), a programmed death-ligand 1 (PD-L1) inhibitor, in extensive-stage small cell lung cancer (“SCLC”). The Company will sponsor the clinical combin…

and the attached Exhibit 99.1 are being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall they be deemed to be incorporated by reference in any filing made by the Company under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Other Events. On January 11, 2026, IDEAYA Biosciences, Inc. (the “Company”) provided a business update including an overview of key corporate objectives for 2026. The company will review these updates during its presentation at the 44th Annual J.P. Morgan Healthcare Conference on Monday, January 12, 2026. Among other things, the Company will review its plan to advance four registrational trials, including for IDE849, the Company’s Phase 1 DLL3 TOP1 ADC, as a monotherapy agent in neuroendocrin…

Termination of a Material Definitive Agreement. On December 9, 2025, GlaxoSmithKline Intellectual Property (No. 4) Limited (“GSK”) delivered written notice to IDEAYA Biosciences, Inc. (the “Company”) of its election to terminate the Collaboration, Option and License Agreement, dated June 15, 2020 (as amended, the “Agreement”). This written notice constituted GSK’s formal written follow-up to its December 4 communication to the Company regarding the termination, as referenced in the Company’s…

Other Events. On December 4, 2025, GLAXOSMITHKLINE INTELLECTUAL PROPERTY (NO. 4) (“GSK”) communicated to IDEAYA Biosciences, Inc. (the “Company”) its election to terminate the Collaboration, Option and License Agreement, dated June 15, 2020 (as amended, the “Agreement”). Pursuant to the terms of the Agreement, such termination will be effective ninety (90) days following the date of GSK’s written notice. During the ninety-day transition period, GSK will transfer the Werner Helicase (IDE275) a…

and the attached Exhibit 99.1 are being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall they be deemed to be incorporated by reference in any filing made by the Company under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Other Events. Positive Median Overall Survival Data from Phase 2 Trial of the Darovasertib and Crizotinib Combination in First-line Metastatic Uveal Melanoma On October 17, 2025, IDEAYA Biosciences, Inc. (the “Company”) announced the first reported median overall survival (“OS”) results from its Phase 1/2 clinical trial (OptimUM-01) evaluating darovasertib, the Company’s investigational oral protein kinase C (“PKC”) inhibitor, in combination with Pfizer’s crizotinib, a c-MET inhibitor, as a f…

Entry into a Material Definitive Agreement. On August 29, 2025, IDEAYA Biosciences, Inc. (the “Company”) entered into a License Agreement (the “Agreement”) with Les Laboratoires Servier (“Servier”) pursuant to which the Company granted to Servier an exclusive license under certain intellectual property rights controlled by the Company relating to darovasertib to develop and commercialize products in all countries worldwide except for the United States for all diagnostic, prophylactic and ther…

and the attached Exhibit 99.1 are being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall they be deemed to be incorporated by reference in any filing made by the Company under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Chief Financial Officer and Principal Financial Officer — Joshua Bleharski, Ph.D.: Dr. Joshua Bleharski was promoted to Chief Financial Officer and Principal Financial Officer.

and the attached Exhibit 99.1 are being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall they be deemed to be incorporated by reference in any filing made by the Company under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Director — Susan L. Kelley, M.D.: Dr. Kelley decided not to stand for re-election and will transition into an advisory role.

and the attached Exhibit 99.1 are being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall they be deemed to be incorporated by reference in any filing made by the Company under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Chief Financial Officer — Joshua Bleharski, Ph.D.: The company appointed a new Chief Financial Officer from an external firm.

Entry into a Material Definitive Agreement. On December 29, 2024, IDEAYA Biosciences, Inc. (the “Company”) announced that it had entered into a License Agreement (the “Agreement”), dated December 27, 2024 (the “Effective Date”), with Jiangsu Hengrui Pharmaceuticals Co., Ltd. (“Hengrui Pharma”) pursuant to which Hengrui Pharma granted to the Company an exclusive worldwide license outside of Greater China to develop and commercialize SHR-4849, a novel DLL3-targeting Topo-I-payload antibody drug…

and the attached Exhibit 99.1 are being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall they be deemed to be incorporated by reference in any filing made by the Company under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Other Events. Clinical Update On October 25, 2024, IDEAYA Biosciences, Inc. (the “Company”) announced clinical data from the Company’s Phase 1 expansion dose of IDE397 in patients with methylthioadenosine phosphorylase (“MTAP”)-deletion urothelial cancer and non-small cell lung cancer (“NSCLC”) in a late breaker abstract oral presentation at the 36th edition of the EORTC-NCI-AACR Symposium (“ENA 2024”) in Barcelona, Spain. The Company had additional poster presentations at ENA 2024 that highl…

Other Events. Clinical Update On September 23, 2024, IDEAYA Biosciences, Inc. (the “Company”) announced interim clinical data for darovasertib in neoadjuvant uveal melanoma (“UM”) from the Company’s ongoing company-sponsored Phase 2 trial and guidance from the U.S. Food and Drug Administration (“FDA”) in a Type C meeting, which the Company believes supports the initiation of a potential registration-enabling Phase 3 randomized clinical trial in neoadjuvant UM patients. Darovasertib is a poten…

and the attached Exhibit 99.1 are being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall they be deemed to be incorporated by reference in any filing made by the Company under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Entry into a Material Definitive Agreement. On July 31, 2024, IDEAYA Biosciences, Inc. (the “Company”) announced that it had entered into an Option and License Agreement (the “Agreement”), dated July 30, 2024 (the “Effective Date”), with Biocytogen Pharmaceuticals (Beijing) Co., Ltd. (“Biocytogen”), pursuant to which Biocytogen granted to the Company an option for an exclusive worldwide license to develop and commercialize products in connection with a potential first-in-class B7H3/PTK7 topo-…