Day One Biopharmaceuticals, Inc. Q3 FY2024 earnings call

OJEMDA Launch and Commercialization - OJEMDA net product revenue in Q3 was $20.1 million, more than double the previous quarter. - Over 850 total prescriptions in five months since approval, with high payer approval rates. - Median duration of response for patients in Arm 1 of FIREFLY-1 extended to 18 months. - Focus on enrollment in FIREFLY-2, the global Phase 3 front-line pLGG trial. - Ex-U.S. partnership with Ipsen for OJEMDA registration and commercialization in EU and other territories. ### Pipeline Progress - On track to dose first patients in Q4 2024 or early Q1 2025 in the Phase 1 trial of DAY301, a PTK7-targeted ADC in-licensed midyear. ### Business Development - Actively seeking differentiated clinical stage programs to expand portfolio and drive shareholder value. - Strong financial position with over $0.5 billion in cash to fund operations and portfolio expansion.

The key product segment is OJEMDA. In Q3, OJEMDA net product revenue was $20.1 million, a 145% increase from the previous quarter. Year-to-date, OJEMDA net product revenue is $28.3 million. Additionally, Day One recorded $73.7 million of license revenue in Q3 from the ex-U.S. commercial rights license of tovorafenib to Ipsen, with an incremental $4.5 million of license revenue to be recognized over future years.

FIREFLY-2 - Focus on enrollment in the global Phase 3 front-line pLGG trial. ### DAY301 - On track to dose first patients in Q4 2024 or early Q1 2025. ### Partnership with Ipsen - Working closely with Ipsen to support OJEMDA registration and commercialization in ex-U.S. territories.

• Forward-looking statements may differ from actual results due to risks, uncertainties, and factors in SEC filings. - Need time to fully penetrate the pLGG market due to slow disease progression and infrequent treatment decisions.

Q: Comment on inventory levels in 3Q and going forward A: Charles York mentioned similar guidance of approximately two to four weeks of channel stock on hand, not providing individual numbers further.

Q: Cadence of new patient starts in 3Q A: Jeremy Bender said cadence was very consistent, no significant seasonality, consistent with previous quarters.

Q: Number of patients on drug, EAP vs De Novo, continuation rate A: Lauren Merendino said EAP transition completed, all new patient starts De Novo in Q3, continuation rate in low single-digits.

Q: Traction in community setting physicians A: Lauren Merendino said significant uptake in both academic and community physicians, 80% of prescribers had no prior experience.

Q: Front-line trial enrollment A: Samuel Blackman said front-line trial is for patients needing first systemic therapy, not for those who had MEK inhibitors before.

Q: Cadence of new patient adds in 3Q A: Jeremy Bender said cadence was consistent, no significant seasonality.

Q: Duration of response data translation to real world A: Samuel Blackman commented on clinical side, updated duration of response data gives confidence to prescribers.

Q: Patients on treatment, DAY301 data expectations A: Jeremy Bender said not focusing on specific patient numbers, DAY301 trial to start in Q4 2024 or early Q1 2025, no specific early data guidance yet.

Q: Ipsen collaboration, PTK7 combination work A: Jeremy Bender and Samuel Blackman discussed Ipsen alignment on OJEMDA registration, PTK7 Phase 1 trial focused on monotherapy signal, combination work for later stages if needed.