Day One Biopharmaceuticals announced the acceptance of three abstracts at the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting to take place in Chicago, IL from June 2 -- 6, 2023. An oral presentation will include new clinical data from the ongoing, open label, pivotal Phase 2 FIREFLY-1 trial evaluating the investigational agent tovorafenib in recurrent or progressive pediatric low-grade glioma (pLGG). Details of the oral presentation are as follows: Title: Clinical activity of pan-RAF inhibitor tovorafenib in the registrational pediatric low-grade glioma arm of the phase 2 FIREFLY-1 (PNOC026) study.

Abstract Number: 10004 Abstract Session: Pediatric Oncology I Date/Time: June 4, 2023, 9:45 AM - 12:45 PM Presenter: Lindsay Kilburn, M.D., Neuro-Oncology Center for Cancer and Blood Disorders, Children's National Medical Center The abstract highlighting topline data from FIREFLY-1 as of September 28(,) 2022 will be available on meetings.asco.org on May 25 at 5:00 PM ET. The oral presentation on June 4, 2023 will highlight new data from the registrational study, including patient follow-up beyond September 28, 2022. The presentation will be available on the Day One website shortly after the live presentation, with a conference call to follow later that evening.

In addition, two posters will be presented on tovorafenib and healthcare resource data: Poster Presentation Details Title: A phase 3, randomized trial of tovorafenib vs. chemotherapy in pediatric and young adult patients with newly diagnosed low-grade glioma harboring an activating RAF alteration. Abstract Number: TPS10067 Abstract Session: Pediatric Oncology Date/Time: June 5, 2023, 1:15 PM - 4:15 PM Presenter: Cornelis M. van Tilburg, MD, PhD, Hopp Children's Cancer Center Heidelberg, Heidelberg University Hospital and German Cancer Research Center Title: Healthcare resource use for pediatric low-grade glioma care: A cohort of linked electronic health records and claims data.

Abstract Number: 10038 Abstract Session: Pediatric Oncology Date/Time: June 5, 2023, 1:15 PM - 4:15 PM Presenter: Tab Cooney, MD, Day One Biopharmaceuticals Day One will also have a Medical Information booth at the 2023 ASCO Annual Meeting at booth number 27155.