Day One Biopharmaceuticals Investor Presentation — November 2022

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Targeted Therapies for People of

June 2022Disclaimer

This presentation and the accompanying oral commentary contain forward -looking statements that are based on our management’s bel iefs and assumptions and on information

currently available to our management. Forward -looking statements are inherently subject to risks and uncertainties, some of whi ch cannot be predicted or quantified. In some

cases, you can identify forward -looking statements by terminology such as “may,” “will,” “should,” “could,” “expect,” “plan,” anticipate,” “believe,” “estimate,” “predict,” “intend,”

“potential,” “would,” “continue,” “ongoing” or the negative of these terms or other comparable terminology. Forward -looking statements include all statements other than

statements of historical fact contained in this presentation, including information concerning our future financial performance, including the sufficiency of our cash and cash

equivalents to fund our operations, business plans and objectives, timing and success of our planned nonclinical and clinical development activities, timing and results of

nonclinical studies and clinical trials, efficacy and safety profile of our product candidates, the execution of the Phase 2 cli nical trial for tovorafenib and the Phase 1b/2 clinical trial

for tovorafenib and pimasertib as designed, any expectations about safety, efficacy, timing and ability to complete clinical trials and to ob tain regulatory approvals for tovorafenib

and other candidates in development, the ability of tovorafenib to treat pLGG or related indications, the potential therapeutic benefits and economic value of our product

candidates, potential growth opportunities, competitive position, industry environment and potential market opportunities, ou r ability to protect intellectual property, and the

impact of global business or macroeconomic conditions, including as a result of the COVID -19 pandemic, inflation, and rising interest rates, on our business and operations.

Forward -looking statements are subject to known and unknown risks, uncertainties, assumptions and other factors. It is not possi ble for our management to predict all risks, nor

can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cau se actual results to differ materially from those

contained in any forward -looking statements we may make. These factors, together with those that are described under the heading “Risk Factors” contained in our most recent

Quarterly Report on Form 10 -Q filed with the Securities and Exchange Commission (“SEC”) and other documents we file from time to time with the SEC, may cause our actual