UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-40431 DAY ONE BIOPHARMACEUTICALS, INC. (Exact Name of Registrant as Specified in its Charter) Delaware 83-2415215 (State or oth ...

Exhibit 99.1 Day One Reports First Quarter 2024 Financial Results and Corporate Progress OJEMDA™ (tovorafenib) launch underway following U.S. FDA accelerated approval for relapsed or refractory BRAF-altered Pediatric Low-Grade Glioma (pLGG) First prescriptions received in the U.S. BRISBANE, Calif., May 6, 2024 – Day One Biopharmaceuticals (Nasdaq: DAWN) ("Day One" or the "Company"), a commercial-stage biopharmaceutical company dedicated to developing and commercializing targeted therapies for people of all ...

OJEMDA™ (tovorafenib) launch underway following U.S. FDA accelerated approval for relapsed or refractory BRAF-altered Pediatric Low-Grade Glioma (pLGG) First prescriptions received in the U.S. BRISBANE, Calif., May 06, 2024 (GLOBE NEWSWIRE) -- Day One Biopharmaceuticals (NASDAQ:DAWN) ("Day One" or the "Company"), a commercial-stage biopharmaceutical company dedicated to developing and commercializing targeted therapies for people of all ages with life-threatening diseases, today announced its first quarter ...

First and only FDA-approved type II RAF inhibitor for patients with relapsed or refractory pLGG harboring a BRAF fusion or rearrangement, or BRAF V600 mutation RAPNO LGG overall response rate (ORR) of 51% Day One receives rare pediatric disease priority review voucher Conference call and webcast to be April 24, 8:30 a.m. Eastern Time BRISBANE, Calif., April 23, 2024 (GLOBE NEWSWIRE) -- Day One Biopharmaceuticals, Inc. (NASDAQ:DAWN) ("Day One" or the "Company"), a commercial-stage biopharmaceutical company ...

PDUFA target action date for tovorafenib NDA in relapsed or progressive pLGG remains set for April 30, 2024 Phase 2 FIREFLY-1 tovorafenib registrational data published in Nature Medicine Ended 2023 with $366.3 million in cash, cash equivalents and short-term investments providing runway into 2026 BRISBANE, Calif., Feb. 26, 2024 (GLOBE NEWSWIRE) -- Day One Biopharmaceuticals (NASDAQ:DAWN) ("Day One" or the "Company"), a clinical-stage biopharmaceutical company dedicated to developing and commercializing targ ...

Exhibit 99.1 Day One Reports Fourth Quarter and Full Year 2023 Financial Results and Corporate Progress PDUFA target action date for tovorafenib NDA in relapsed or progressive pLGG remains set for April 30, 2024 Phase 2 FIREFLY-1 tovorafenib registrational data published in Nature Medicine Ended 2023 with $366.3 million in cash, cash equivalents and short-term investments providing runway into 2026 BRISBANE, Calif., Feb. 26, 2024 – Day One Biopharmaceuticals (Nasdaq: DAWN) ("Day One" or the "Company"), a cl ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number 001-40431 DAY ONE BIOPHARMACEUTICALS, INC. (Exact name of Registrant as specified in its Charter) Delaware 83-2415215 (State or other jur ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-40431 DAY ONE BIOPHARMACEUTICALS, INC. (Exact Name of Registrant as Specified in its Charter) Delaware 83-2415215 (State or ...

MR(includes 4 uMR) PD# All 4 patients with uPR and 3 patients with uMR remain on treatment as of May 23, 2023 20 (26%) MAPKi-naive Prior MAPKi therapy BRAF V600E mutation Best Tumor Response (%) -100 -80 -60 -40 -20 0 20 40 60 80 180 100 PD SD PR CR MR SD PD# Best overall response, n (%) CR Dec 22, 2022 data cutoff. Percents may not add to 100% due to rounding. #PD for RANO-LGG was not used to determine treatment discontinuation; patients could continue treatment if there was no PD based on RANO-HGG per inv ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-40431 DAY ONE BIOPHARMACEUTICALS, INC. (Exact Name of Registrant as Specified in its Charter) Delaware 83-2415215 (State or othe ...