Organization	6 Months Ended
Jun. 30, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	1. Organization Description of the Business IDEAYA Biosciences, Inc. (the “Company”) is a precision medicine oncology company committed to the discovery, development and commercialization of transformative therapies to address unmet medical needs in cancer. The Company is headquartered in South San Francisco, California and was incorporated in the State of Delaware in June 2015. Follow-On Offering In June 2026, the Company completed an underwritten public follow-on offering. The offering consisted of 7,222,225 shares of common stock at an offering price to the public of $27.00 per share, including 1,666,669 shares of common stock upon the exercise in full of the overallotment option by the underwriters, as well as pre-funded warrants to purchase 5,555,576 shares of common stock at a public offering price of $26.9999 per underlying share, in each case before underwriting discounts and commissions. Pursuant to the offering, the Company received aggregate gross proceeds of approximately $345.0 million and net proceeds of $323.4 million, after deducting underwriting discounts and commissions and other offering expenses. At-the-Market Offering On January 19, 2024, the Company entered into an Open Market Sales Agreement (the “January 2024 Sales Agreement”) with Jefferies, relating to an at-the-market offering program under which the Company may offer and sell, from time to time at its sole discretion, shares of common stock having aggregate gross proceeds of up to $350.0 million through Jefferies as sales agent. During the year ended December 31, 2025, the Company sold an aggregate of 984,000 shares of its common stock for aggregate net proceeds of $25.0 million at a weighted average sales price of approximately $26.00 per share under the at-the-market offering pursuant to the January 2024 Sales Agreement with Jefferies as sales agent. During the three months ended June 30, 2026, the Company sold an aggregate of 1,196,423 shares of the Company's common stock for aggregate net proceeds of $33.1 million at a weighted average sales price of approximately $28.38 per share under the at-the-market offering pursuant to the January 2024 Sales Agreement with Jefferies as sales agent. As of June 30, 2026, approximately $122.6 million of common stock remained available to be sold pursuant to the January 2024 Sales Agreement. The Company may cancel its at-the-market offering program at any time upon written notice, pursuant to its terms. Liquidity The Company has primarily incurred significant losses and negative cash flows from operations in all periods since inception and had an accumulated deficit of $947.5 million as of June 30, 2026. The Company has financed its operations primarily through the sale and issuance of common stock, the upfront payment and certain milestone payments received under the Company's former collaboration agreement with GSK (as defined below) and the upfront payment received from Servier under the Servier License Agreement. To date, none of the Company’s product candidates have been approved for sale, and the Company has not generated any revenue from commercial products since inception. Management expects operating losses to continue and increase for the foreseeable future, as the Company progresses clinical development activities for its lead product candidates. The Company’s prospects are subject to risks, expenses and uncertainties frequently encountered by companies in the biotechnology industry as discussed under Risks and Uncertainties in Note 2. While the Company has been able to raise multiple rounds of financing, there can be no assurance that in the event the Company requires additional financing, such financing will be available on terms which are favorable or at all. Failure to generate sufficient cash flows from operations, raise additional capital or reduce certain discretionary spending would have a material adverse effect on the Company’s ability to achieve its intended business objectives. As of June 30, 2026, the Company had cash, cash equivalents and marketable securities of approximately $1.24 billion. Management believes that the Company’s current cash, cash equivalents and marketable securities will be sufficient to fund its planned operations for at least twelve months from the date of the issuance of this Quarterly Report on Form 10-Q.

Organization

6 Months Ended

Jun. 30, 2026

Organization, Consolidation and Presentation of Financial Statements [Abstract]

1. Organization

Description of the Business

IDEAYA Biosciences, Inc. (the “Company”) is a precision medicine oncology company committed to the discovery, development and commercialization of transformative therapies to address unmet medical needs in cancer. The Company is headquartered in South San Francisco, California and was incorporated in the State of Delaware in June 2015.

Follow-On Offering

In June 2026, the Company completed an underwritten public follow-on offering. The offering consisted of 7,222,225 shares of common stock at an offering price to the public of $27.00 per share, including 1,666,669 shares of common stock upon the exercise in full of the overallotment option by the underwriters, as well as pre-funded warrants to purchase 5,555,576 shares of common stock at a public offering price of $26.9999 per underlying share, in each case before underwriting discounts and commissions. Pursuant to the offering, the Company received aggregate gross proceeds of approximately $345.0 million and net proceeds of $323.4 million, after deducting underwriting discounts and commissions and other offering expenses.

At-the-Market Offering

On January 19, 2024, the Company entered into an Open Market Sales Agreement (the “January 2024 Sales Agreement”) with Jefferies, relating to an at-the-market offering program under which the Company may offer and sell, from time to time at its sole discretion, shares of common stock having aggregate gross proceeds of up to $350.0 million through Jefferies as sales agent.

During the year ended December 31, 2025, the Company sold an aggregate of 984,000 shares of its common stock for aggregate net proceeds of $25.0 million at a weighted average sales price of approximately $26.00 per share under the at-the-market offering pursuant to the January 2024 Sales Agreement with Jefferies as sales agent.

During the three months ended June 30, 2026, the Company sold an aggregate of 1,196,423 shares of the Company's common stock for aggregate net proceeds of $33.1 million at a weighted average sales price of approximately $28.38 per share under the at-the-market offering pursuant to the January 2024 Sales Agreement with Jefferies as sales agent.

As of June 30, 2026, approximately $122.6 million of common stock remained available to be sold pursuant to the January 2024 Sales Agreement.

The Company may cancel its at-the-market offering program at any time upon written notice, pursuant to its terms.

Liquidity

The Company has primarily incurred significant losses and negative cash flows from operations in all periods since inception and had an accumulated deficit of $947.5 million as of June 30, 2026.

The Company has financed its operations primarily through the sale and issuance of common stock, the upfront payment and certain milestone payments received under the Company's former collaboration agreement with GSK (as defined below) and the upfront payment received from Servier under the Servier License Agreement.

To date, none of the Company’s product candidates have been approved for sale, and the Company has not generated any revenue from commercial products since inception. Management expects operating losses to continue and increase for the foreseeable future, as the Company progresses clinical development activities for its lead product candidates. The Company’s prospects are subject to risks, expenses and uncertainties frequently encountered by companies in the biotechnology industry as discussed under Risks and Uncertainties in Note 2. While the Company has been able to raise multiple rounds of financing, there can be no assurance that in the event

the Company requires additional financing, such financing will be available on terms which are favorable or at all. Failure to generate sufficient cash flows from operations, raise additional capital or reduce certain discretionary spending would have a material adverse effect on the Company’s ability to achieve its intended business objectives.

As of June 30, 2026, the Company had cash, cash equivalents and marketable securities of approximately $1.24 billion. Management believes that the Company’s current cash, cash equivalents and marketable securities will be sufficient to fund its planned operations for at least twelve months from the date of the issuance of this Quarterly Report on Form 10-Q.