8-K
0001845337false00018453372023-11-062023-11-06

 

 

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

 

 

FORM 8-K

 

 

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): November 06, 2023

 

 

DAY ONE BIOPHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

 

 

 

Delaware

001-40431

83-2415215

(State or other jurisdiction
of incorporation)

(Commission File Number)

(IRS Employer
Identification No.)

 

 

 

 

 

2000 Sierra Point Parkway, Suite 501

 

Brisbane, California

 

94005

(Address of principal executive offices)

 

(Zip Code)

 

Registrant’s telephone number, including area code: (650) 484-0899

 

 

N/A

 

(Former name or former address, if changed since last report)

 

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:


Title of each class

 

Trading
Symbol(s)

 


Name of each exchange on which registered

Common Stock, par value $0.0001 per share

 

DAWN

 

Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.

 

 

 


 

Item 2.02 Results of Operations and Financial Condition.

On November 6, 2023, Day One Biopharmaceuticals, Inc. (the "Company") issued a press release announcing its financial results for the quarter ended September 30, 2023. A copy of the press release is attached as Exhibit 99.1 to this report.

Item 7.01 Regulation FD Disclosure.

On November 6, 2023, the Company updated its corporate presentation. A copy of the updated presentation is attached as Exhibit 99.2 to this report.

 

The information in this Current Report on Form 8-K, including Exhibit 99.1 and Exhibit 99.2 to this report, shall not be deemed to be “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended (the “Securities Act”). The information contained in this Current Report on Form 8-K and in the accompanying Exhibit 99.1 and Exhibit 99.2 shall not be incorporated by reference into any other filing under the Exchange Act or under the Securities Act, except as shall be expressly set forth by specific reference in such filing.

Item 9.01 Financial Statements and Exhibits.

(d)

Exhibits

 

 

 

Exhibit

Number

Description

 

 

99.1

Press release issued by Day One Biopharmaceuticals, Inc. regarding its financial results for the quarter ended September 30, 2023, dated November 6, 2023.

 

 

 

99.2

 

Corporate Presentation.

 

 

 

104

Cover Page Interactive Data File (embedded within the Inline XBRL document).

 

 

 


 

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

 

 

 

DAY ONE BIOPHARMACEUTICALS, INC.

 

 

 

 

Date:

November 6, 2023

By:

/s/ Charles N. York II, M.B.A.

 

 

 

Charles N. York II, M.B.A.
Chief Operating Officer and Chief Financial Officer

 

 


EX-99.1

Exhibit 99.1

https://cdn.kscope.io/8a457af83df6c64cc18fe885cb658ce1-img109617361_0.jpg 

 

Day One Reports Third Quarter 2023 Financial Results and Corporate Progress

 

NDA for tovorafenib in relapsed or progressive pLGG accepted for FDA priority review

 

PDUFA target action date of April 30, 2024

 

 

BRISBANE, Calif., Nov. 6, 2023 – Day One Biopharmaceuticals (Nasdaq: DAWN) (“Day One” or the “Company”), a clinical-stage biopharmaceutical company dedicated to developing and commercializing targeted therapies for people of all ages with life-threatening diseases, today announced its third quarter 2023 financial results and highlighted recent corporate achievements.

 

“Day One made significant progress this past quarter towards potentially bringing tovorafenib to children with cancer, most notably with the completion of the tovorafenib rolling submission to the FDA,” said Jeremy Bender, Ph.D., chief executive officer of Day One. “We’re excited the FDA has granted a Priority Review and set a PDUFA date of April 30. Our commercial launch preparation is fully underway, including the hiring of a national sales force.”

 

Program Highlights

 

In September 2023, the Company announced updated FIREFLY-1 data for tovorafenib and completion of the rolling New Drug Application (NDA) submission to the U.S. Food and Drug Administration (FDA) for relapsed or progressive pediatric low-grade glioma (pLGG).

 

In October 2023, Day One announced that the FDA accepted its NDA for Priority Review. The Company anticipates being eligible for a Priority Review Voucher upon potential approval of tovorafenib.

 

The FDA has assigned a Prescription Drug User Fee Act (PDUFA) target action date of April 30, 2024.

 

Day One presented two case reports at the 2023 Connective Tissue Oncology Society Annual Meeting in November 2023, documenting fusion-driven sarcoma case reports from the FIREFLY-1 and FIRELIGHT-1 studies.

 

Day One has concluded enrollment in the Phase 2a FIRELIGHT-1 substudy trial of tovorafenib as a monotherapy in patients 12 years and older with relapsed, progressive, or refractory solid tumors harboring MAPK pathway aberrations. Despite observing responses with a generally well-tolerated therapy, a limited duration of response in this relatively rare patient population was observed. Day One will discontinue this monotherapy substudy and re-direct resources to

Page 1 of 6

 


Exhibit 99.1

other programs. Results from the substudy will be shared for presentation or publication after the final dataset becomes available.

 

Patient enrollment continues in the Phase 1b/2 substudy (102b) of the FIRELIGHT-1 trial evaluating the combination of tovorafenib with the Company’s investigational MEK inhibitor, pimasertib.

 

The pivotal Phase 3 FIREFLY-2/LOGGIC clinical trial evaluating tovorafenib as a front-line therapy in patients aged 6 months to 25 years with pLGG continues to enroll in the United States, Canada, Europe, Australia and Asia, with approximately 70 sites activated.

 

Corporate Highlights and Upcoming Milestones

 

In August 2023, Day One entered into a research collaboration and license agreement with Sprint Biosciences AB for its Vaccinia Related Kinase 1 (VRK1) program, augmenting the Company’s portfolio of targeted therapies in oncology.

 

The Company has appointed Adam Dubow, Day One’s current General Counsel, as one of its executive officers under Section 16 of the Securities Exchange Act of 1934, as amended. Mr. Dubow joined Day One in October 2022 and leads the legal and compliance functions.

 

Third Quarter 2023 Financial Highlights

 

Cash Position: Cash, cash equivalents and short-term investments totaled $405.5 million on September 30, 2023. Based on Day One’s current operating plan, management believes it has sufficient capital resources to fund anticipated operations into 2026.

 

R&D Expenses: Research and development expenses were $33.2 million for the third quarter of 2023 compared to $22.0 million for the third quarter of 2022. The increase was primarily due to additional employee compensation costs, an upfront license payment, as well as clinical trial and manufacturing activities related to Day One’s lead product candidate, tovorafenib.

 

G&A Expenses: General and administrative expenses were $18.3 million for the third quarter of 2023 compared to $17.7 million for the third quarter of 2022. The increase was primarily due to additional employee compensation costs, as well as the ongoing build-out of commercial capabilities.

 

Net Loss: Net loss totaled $46.2 million for the third quarter of 2023 with non-cash stock compensation expense of $9.6 million, compared to $37.8 million for the third quarter of 2022 with non-cash stock compensation expense of $8.6 million.

 

Upcoming Events

 

Clinical data from the ongoing, open-label, pivotal Phase 2 FIREFLY-1 clinical trial evaluating the investigational agent tovorafenib in relapsed or progressive pLGG will be presented in two plenary presentations at the 2023 Society for Neuro-Oncology Annual Meeting on November 17, 2023.

Page 2 of 6

 


Exhibit 99.1

 

Piper Sandler 35th Annual Healthcare Conference, November 28-30, 2023.

 

About Tovorafenib

Tovorafenib is an investigational, oral, brain-penetrant, highly-selective type II RAF kinase inhibitor designed to target a key enzyme in the MAPK signaling pathway, which is being investigated in primary brain tumors or brain metastases of solid tumors. Tovorafenib has been studied in over 325 patients to date and is currently under evaluation in two pivotal clinical trials for pLGG. Tovorafenib is also being evaluated as a combination therapy for adolescent and adult patient populations with recurrent or progressive solid tumors with MAPK pathway aberrations (FIRELIGHT-1).

 

Tovorafenib has been granted Breakthrough Therapy and Rare Pediatric Disease designations by the U.S. Food and Drug Administration (FDA) for the treatment of patients with pLGG harboring an activating RAF alteration. Tovorafenib has also received Orphan Drug designation from the FDA for the treatment of malignant glioma, and from the European Commission for the treatment of glioma.

 

About Day One Biopharmaceuticals

Day One Biopharmaceuticals is a clinical-stage biopharmaceutical company that believes when it comes to pediatric cancer, we can do better. We put kids first and are developing targeted therapies that deliver to their needs. Day One was founded to address a critical unmet need: the dire lack of therapeutic development in pediatric cancer. The Company’s name was inspired by “The Day One Talk” that physicians have with patients and their families about an initial cancer diagnosis and treatment plan. Day One aims to re-envision cancer drug development and redefine what’s possible for all people living with cancer—regardless of age—starting from Day One.

 

Day One partners with leading clinical oncologists, families, and scientists to identify, acquire, and develop important emerging cancer treatments. The Company’s lead product candidate, tovorafenib, is an investigational, oral, brain-penetrant, highly-selective type II RAF kinase inhibitor. The Company’s pipeline also includes pimasertib, an investigational, oral, highly-selective small molecule inhibitor of mitogen‐activated protein kinases 1 and 2 (MEK-1/-2). Day One is based in Brisbane, California. For more information, please visit www.dayonebio.com or find the Company on LinkedIn or Twitter.

 

Cautionary Note Regarding Forward-Looking Statements

This press release contains “forward-looking” statements within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995, including, but not limited to: Day One’s plans to develop cancer therapies, expectations from current clinical trials, the execution of the Phase 2 and Phase 3 clinical trials for tovorafenib as designed, any expectations about safety, efficacy, timing and ability to complete clinical trials, release data results, the ability of Day One to obtain regulatory approvals for and to commercialize tovorafenib and other candidates in development, and the ability of tovorafenib to treat pLGG or related indications.

 

Statements including words such as “believe,” “plan,” “continue,” “expect,” “will,” “develop,” “signal,” “potential,” or “ongoing” and statements in the future tense are forward-looking statements. These forward-looking statements involve risks and uncertainties, as well as assumptions, which, if they do not fully materialize or prove incorrect, could cause our results to differ materially from those expressed or implied by such forward-looking statements.

 

Page 3 of 6

 


Exhibit 99.1

Forward-looking statements are subject to risks and uncertainties that may cause Day One’s actual activities or results to differ significantly from those expressed in any forward-looking statement, including risks and uncertainties in this press release and other risks set forth in our filings with the Securities and Exchange Commission, including Day One’s ability to develop, obtain regulatory approval for or commercialize any product candidate, Day One’s ability to protect intellectual property, the potential impact of global business or macroeconomic conditions, including as a result of inflation, rising interest rates, cybersecurity events, instability in the global banking system, government shutdowns, uncertainty with respect to the federal budget, geopolitical conflicts and the sufficiency of Day One’s cash, cash equivalents and investments to fund its operations. These forward-looking statements speak only as of the date hereof and Day One specifically disclaims any obligation to update these forward-looking statements or reasons why actual results might differ, whether as a result of new information, future events or otherwise, except as required by law.

 

Day One Biopharmaceuticals, Inc.

Consolidated Statements of Operations

(unaudited)

(in thousands, except shares)

 

 

 

Three Months Ended
September 30,

 

Nine Months Ended
September 30,

 

2023

 

2022

 

2023

 

2022

Operating expenses:

 

 

 

 

 

 

 

Research and development

$ 33,163

 

$ 22,035

 

$ 93,173

 

$ 59,598

General and administrative

    18,275

 

  17,664

 

  53,374

 

  44,568

Total operating expenses

  51,438

 

  39,699

 

  146,547

 

  104,166

Loss from operations

  (51,438)

 

  (39,699)

 

  (146,547)

 

  (104,166)

Investment income, net

  5,291

 

  1,895

 

  12,163

 

  2,086

Other (expense) income, net

  (3)

 

  9

 

  (22)

 

  8

Net loss attributable to common stockholders

  (46,150)

 

  (37,795)

 

  (134,406)

 

  (102,072)

Net loss per share, basic and diluted

$ (0.54)

 

$ (0.53)

 

$ (1.73)

 

$ (1.61)

Weighted-average number of common shares used in computing net loss per share, basic and diluted

85,952,501

 

71,008,993

 

77,682,237

 

63,522,774

 

 

 

 

Day One Biopharmaceuticals, Inc.

Selected Consolidated Balance Sheet Data

(unaudited)

(in thousands)

 

 

 

 

September 30,
2023

 

December 31,
2022

Cash, cash equivalents and short-term investments

 

$ 405,538

 

$ 342,269

Total assets

 

  414,179

 

  349,062

Total liabilities

 

  24,552

 

  17,023

Accumulated deficit

 

  (404,074)

 

  (269,668)

Total stockholders’ equity

 

  389,627

 

  332,039

 

Page 4 of 6

 


Exhibit 99.1

 

 

 

DAY ONE MEDIA

Laura Cooper, Head of Communications

media@dayonebio.com

 

DAY ONE INVESTORS

LifeSci Advisors, PJ Kelleher

pkelleher@lifesciadvisors.com

 

#####

 

 

 

Page 5 of 6

 


Slide 1

Day One Biopharmaceuticals Targeted Therapies for People of All Ages November 2023


Slide 2

Disclaimer This presentation and the accompanying oral commentary contain forward-looking statements that are based on our management’s beliefs and assumptions and on information currently available to our management. Forward-looking statements are inherently subject to risks and uncertainties, some of which 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, cash equivalents and short-term investments to fund our operations, business plans and objectives, timing and success of our planned nonclinical and clinical development activities, the results of any of our strategic collaborations, including the potential achievement of milestones and provision of royalty payments thereunder, timing and results of nonclinical studies and clinical trials, efficacy and safety profiles of our product candidates, execution of the Phase 2 and Phase 3 clinical trials 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 obtain regulatory approvals for tovorafenib and other candidates in development, the ability of tovorafenib to treat pediatric low-grade glioma (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, our ability to protect intellectual property and the impact of global business or macroeconomic conditions, including as a result of inflation, rising interest rates, cybersecurity incidents, instability in the global banking system, government shutdowns, uncertainty with respect to the federal budget and geopolitical conflicts, including the conflicts in Israel and Ukraine, on our business and operations. Forward-looking statements are subject to known and unknown risks, uncertainties, assumptions and other factors. It is not possible 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 cause 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 results, performance or achievements to differ materially and adversely from those anticipated or implied by our forward-looking statements. In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of this presentation, and although we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted a thorough inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and investors are cautioned not to unduly rely upon these statements. Furthermore, if our forward-looking statements prove to be inaccurate, the inaccuracy may be material. In light of the significant uncertainties in these forward-looking statements, you should not regard these statements as a representation or warranty by us or any other person that we will achieve our objectives and plans in any specified time frame, or at all. We undertake no obligation to publicly update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law. This presentation also contains estimates and other statistical data made by independent parties and by us relating to market size and growth and other data about our industry. This data involves a number of assumptions and limitations, and you are cautioned not to give undue weight to such estimates. In addition, projections, assumptions and estimates of our future performance and the future performance of the markets in which we operate are necessarily subject to a high degree of uncertainty and risk.


Slide 3

Cancer Drug Development For People Of All Ages NDA data set included analysis of primary (ORR by RANO-HGG) and secondary (ORR by RAPNO-LGG, PFS) efficacy endpoints, safety, and exploratory analyses (including ORR by RANO-LGG). A Mission That Creates Value Develop medicines for genomically-defined cancers Establish first-in-class position through rapid registration pathways Expand to adolescent and adult populations in parallel and pursue those opportunities with the same commitment we do for children Nasdaq: DAWN IPO: 2021 Founded: 2018 Financial Position Runway into 2026 Growing Portfolio Lead program FIREFLY-1: FDA acceptance of NDA and priority review granted with PDUFA target action of date of April 30, 2024 Frontline trial (FIREFLY-2) underway Clinical-stage MEKi asset (pimasertib), in-licensed for combination trial with tovorafenib Research collaboration and license agreement for preclinical program targeting VRK1


Slide 4

Our Pipeline Product Candidate Indication Preclinical Phase 1 Phase 2 Phase 3 Recent & Anticipated Milestones Tovorafenib (DAY101) Type II RAF Inhibitor Relapsed pLGG Frontline pLGG Pimasertib MEK 1/2 Inhibitor MAPK-altered solid tumors2 (Combo w/tovorafenib) VRK1 Program3 VRK1 Inhibitor Pediatric and adult cancers FDA Breakthrough Therapy Designation for relapsed pLGG FDA Orphan Drug Designation for malignant glioma EC Orphan Designation for glioma FDA Rare Pediatric Disease Designation (PRV Eligible) for pLGG FIREFLY-11 (pivotal) FIREFLY-2 (pivotal) FIRELIGHT-1* First patient dosed: March 2023 First patient dosed: May 2022 Topline data presented: September 2023 FDA acceptance of NDA: October 2023 PDUFA target action date: April 30, 2024 In-licensed: August 2023 *Includes patients ≥12 years of age. 1 FIREFLY-1 Arm 1 expected to support registration. 2 Pimasertib Phase 1 dose escalation and expansion trial previously completed. 3 Research collaboration and license agreement with Sprint Bioscience for exclusive worldwide rights to a research-stage program targeting VRK1. pLGG, pediatric low-grade glioma. Tovorafenib and Pimasertib are investigational products. Safety and efficacy have not been established by any health authority.


Slide 5

Tovorafenib (DAY101) Type II RAF Inhibitor


Slide 6

Pediatric Low-Grade Glioma (pLGG): The Most Common Type Of Brain Tumor In Children PLGGs are chronic and relentless, with patients suffering profound tumor and treatment-associated morbidity that can impact their life trajectory over the long term6 A Serious and Life-Threatening Disease Disease Symptoms7 Cerebral gliomas: Seizures, muscle weakness, behavioral changes Hypothalamic gliomas: Endocrine dysfunction and visual deficits Optic pathway gliomas: Decreased vision (acuity and/or fields), bulging or misalignment of eyes Cerebellar gliomas: Impaired balance, coordination or depth perception Brain stem gliomas: Difficulty swallowing or with speech, abnormal breathing An estimated 26,000 children/young adults are living with BRAF-altered pLGGs in the U.S. today1,2 Surgery plays a significant role in treatment, but 70% of patients require systemic therapy3,4 For the majority of patients in the relapse setting, there is no standard of care and no approved therapies ~70% of pLGGs have BRAF alterations, of these ~85% are BRAF fusions and ~15% are BRAF V600E mutations5 Majority of patients have many years of treatment until the tumors typically senesce by their mid-20s 1 CBTRUS, Qaddoumi et al 2009, Schreck et al 2019, ClearView Analysis; 2 SEER US complete prevalence counts of patients aged under 25 with Brain and Other Nervous Systems tumors as of January 1, 2017. Estimated prevalence are Day One calculations based on publicly available data. 3 Ostrum QT et al., Neuro Oncol. 2015; 16(Suppl 10):x1-x36; 4 De Blank P. et al., Curr Opin Pediatr. 2019 Feb; 31(1):21-27. 5 Jones DTW et al., Cancer Res. 2008; 68:8673–77. 6 Traunwieser T et al., Neurooncol Adv. 2020; 2:vdaa094. 7 Sievert AJ, Fisher MJ. Pediatric low-grade gliomas. J Child Neurol. 2009;24(11):1397-1408. doi:10.1177/0883073809342005.


Slide 7

Conventional Treatments Can Be Disruptive To Childhood and Can Have Significant Long-Term Consequences Significant recovery times Risks of complications Resection may be limited by location of tumor Potential for functional deficits based on location of tumor and extent of resection Risk of secondary malignancy Risk of malignant transformation Risk of vascular proliferation and stroke Neurocognitive impact, depending on location of tumor and radiation field Surgery Chemotherapy Radiation Requirement for indwelling catheter and weekly infusions Risk of neutropenia, hypersensitivity reactions, nausea and vomiting and peripheral neuropathy High unmet need for an effective therapy for the majority of pLGG relapsed or progressive patients that is minimally disruptive to their lives. Source: 1. Heitzer AM, Raghubar K, Ris MD, et al. Neuropsychological functioning following surgery for pediatric low-grade glioma: a prospective longitudinal study. J Neurosurg Pediatr. 2019;1-9. doi:10.3171/2019.9.PEDS19357. 2. Bryant R. Managing side effects of childhood cancer treatment. J Pediatr Nurs. 2003;18(2):113-125. doi:10.1053/jpdn.2003.11. 3. Zahnreich S, Schmidberger H. Childhood cancer: occurrence, treatment and risk of second primary malignancies. Cancers (Basel). 2021;13(11):2607. doi:10.3390/cancers/13112607. 4. National Cancer Institute. Fertility issues in girls and women with cancer. http://www.cancer.gov. Accessed June 13, 2022. 5. Alessi I., Caroleo A.M., de Palma L., Mastronuzzi A., Pro S., Colafati G.S., Boni A., Della Vecchia N., Velardi M., Evangelisti M., et al. Short and Long-Term Toxicity in Pediatric Cancer Treatment: Central Nervous System Damage. Cancers. 2022;14:1540. doi: 10.3390/cancers14061540.


Slide 8

Tovorafenib (DAY101) Inhibits Both BRAF Fusions And BRAF V600 Mutations Tovorafenib (DAY101) is an investigational, oral, selective, CNS-penetrant, type II RAF inhibitor that was designed to inhibit both monomeric and dimeric RAF kinase Activity in tumors driven by both RAF fusions and BRAF V600E mutations Tablet and pediatric-friendly liquid suspension Once weekly dosing Currently approved type I BRAFi are indicated for use in patients with tumors bearing BRAF V600E mutations Type I BRAF inhibitors cause paradoxical MAPK activation in the setting of wild-type RAF, increasing the risk of tumor growth in BRAF fusion-driven RAS-independent activation of the MAPK pathway MAPK pathway RAS RAF MEK ERK Proliferation and survival RAF mutation RAF fusion Proliferation and survival Proliferation and survival Tovorafenib Source: 1. Sun Y et al., Neuro Oncol. 2017; 19: 774–85; 2. Sievart AJ et al., PNAS. 2013; 110:5957-62; 3. Karajannis MA et al., Neuro Oncol 2014;16(10):1408-16.


Slide 9

The Current pLGG Treatment Paradigm Reflects The Unrelenting Nature Of This Chronic Brain Tumor Because many pLGGs undergo senescence when patients reach their 20s, the goal of therapy is to maximize tumor control while minimizing treatment-associated toxicities from surgery, chemotherapy, and radiation. As a result, a large number of pLGG patients will undergo multiple lines of systemic therapy over the course of their disease. Surgical Intervention Suspected pLGG GTR No Recurrence Eventual Recurrence ~80% ~20% ~35% Presentation 1L ~35% 2L Response, no recurrence 3L Chemo (~90%) Chemo (~50%) Chemo (~35%) Other (<5%) Other (<5%) Other (<20%) Targeted Tx (5-10%) Targeted Tx (40-50%) Targeted Tx (40-50%) Response, no recurrence ~50% Biopsy Only ~40% ~20% Molecular Testing Biopsy1 (>95%) No Biopsy (~5%) ≤ Partial Resection ~65% ~50% ~50% Additional lines of therapy Source: Physician Interviews, Bandopadhayay et al. Pediatric Blood Cancer. 2014; Sievert and Fischer. J Child Neurol. 2009; ClearView Analysis. GTR: Gross Total Resection 1Molecular testing of biopsied samples occurs in all patients. Kandels et. al. Retrospective analysis of comprehensive SIOP registry; Hargrave et. al. Phase I/II;Fangusaro et. al. Phase II


Slide 10

Pivotal Phase 2 Trial Of Monotherapy Tovorafenib (DAY101) In Relapsed Or Progressive pLGG (FIREFLY-1) – Fully Enrolled & Data Submitted to FDA Primary endpoint: ORR based on RANO-HGG1, assessed by blinded independent central review Secondary endpoints: ORR by RAPNO-LGG2 assessed by blinded independent central review; PFS, DoR; TTR, CBR; safety Exploratory analyses: ORR and CBR by RANO-LGG3 assessed by blinded independent central review Three arm, open-label, global registrational phase 2 trial Pivotal Arm 1 (recurrent/progressive pLGG, n=77): harboring a KIAA1549-BRAF fusion or BRAF V600E mutation Arm 2 (expanded access recurrent/progressive LGG, n=60): harboring an activating RAF alteration Arm 3 (extracranial solid tumors): harboring an activating RAF fusion Endpoints (Pivotal Arm 1) Trial Design Day –28 to 0 Study Drug Administration 420mg/m2 QW (not to exceed 600mg), QW in 28-day cycles After Cycle 27: patients may either continue treatment or enter drug holiday period at any time (at discretion of investigator) Screening C27D1 Enrollment/ Baseline (C1D1) End of Trial Clinical and radiological evaluations at baseline, and every 3rd cycle for pLGG and every 2nd cycle for solid tumors Eligibility evaluation Treatment period: minimum of 2 years or until progression or toxicity/intolerability Key Inclusion Criteria 6 months – 25 years of age RAF-altered tumor ≥1 prior line of systemic therapy with radiographic progression Prior use of MAPK pathway targeted therapy was permitted June 5, 2023 data cutoff. 1 Wen PY, et al. J Clin Oncol. 2010;28(11):1963-1972. 2 Fangusaro J, et al. Lancet Oncol. 2020;21(6):e305–316. 3 van den Bent MJ, et al. Lancet Oncol. 2011;12(6):583-593. Abbreviations: CBR, clinical benefit rate; IRC, independent review committee; C, cycle; D, day; LGG, low-grade glioma; ORR, objective response rate; PFS, progression-free survival; DoR, duration of response; QW, once weekly; TTR, time to response; RANO, Response Assessment in Neuro-Oncology; RAPNO, Response Assessment in Pediatric Neuro-Oncology; MAPK, mitogen-activated protein kinase. For more information, please refer to NCT04775485


Slide 11

Topline Data from Pivotal Phase 2 FIREFLY-1 Trial June 5, 2023 data cutoff


Slide 12

FIREFLY-1 Baseline Patient Characteristics Characteristic Arm 1 (n=77) Median age, years (range) 8 (2-21) Sex, n (%) Male Female 40 (52) 37 (48) Race, n (%) Black or African American Asian White Multiple Other Not reported 2 (3) 5 (6) 41 (53) 3 (4) 6 (8) 20 (26) Number of lines of prior systemic therapy Median (range) 1, n (%) 2, n (%) ≥3, n (%) 3 (1-9) 17 (22) 21 (27) 39 (51) Prior MAPK pathway targeted therapy, n (%) 46 (60) BRAF alteration (n=77) Location (n=77) Optic pathway 51% BRAF V600E 17% BRAF fusion# 83% Cerebellum 6% Deep midline structures 12% Brain stem 8% Cerebral hemisphere 8% Other 16%* June 5, 2023 data cutoff. *Includes tumors that were extending into multiple regions of the brain, leptomeningeal disease, and/or spinal disease. #Includes 6 patients with BRAF duplication and 2 with BRAF rearrangement per FISH (Fluorescence in situ hybridization) or ISH (in situ hybridization). MAPK, mitogen-activated protein kinase.


Slide 13

Topline Data From Ongoing, Fully Enrolled And NDA Submitted Pivotal Phase 2 FIREFLY-1 Trial – June 5, 2023 Data Cutoff June 5, 2023 data cutoff. RANO-HGG ORR (CR + PR). RAPNO-LGG & RANO-LGG ORR (CR + PR + MR), SPPD, Sum of Perpendicular Diameters. CBR, Clinical Benefit Rate (CR + PR + MR + SD). * Indicates the response criteria–evaluable patients within the n=77 Arm 1 population. RANO-HGG (n=69)* RAPNO-LGG (n=76)* RANO-LGG (N=76)* ORR, n (%) 46 (67%) 39 (51%) 40 (53%) CBR, n (%) 64 (93%) 62 (82%) 63 (83%) Best Overall Response, n (%) Complete Response (CR) 12 (17%) - - Partial Response (PR; >=50% reduction in SPPD) 34 (49%) 28 (37%) 20 (26%) Minor Response (MR; >=25 to <50% reduction in SPPD) NA 11 (14%) 20 (26%) Stable Disease (SD; +25% to -25% change in SPPD) 18 (26%) 23 (30%) 23 (30%) Duration of Response (DOR) (months) Median DOR (95% CI) 16.6 (11.6, not estimable) 13.8 (11.3, not estimable) 14.4 (11.0, not estimable) Median duration of tovorafenib treatment of 15.8 months, with 66% of patients remaining on treatment


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Tovorafenib (DAY101) Safety Data (n=137) June 5, 2023 data cutoff. Safety data, based on the 137 patients treated in both Arm 1 and Arm 2 of FIREFLY-1, indicated monotherapy tovorafenib to be generally well-tolerated The vast majority of adverse events were Grade 1 or Grade 2, with most common treatment-related side effects, excluding laboratory abnormalities, being change in hair color (76%), fatigue (44%), maculopapular rash (41%), dry skin (33%) and dermatitis acneiform (30%) The most commonly reported treatment-related lab abnormalities were CPK elevation, LDH elevation, anemia, hypophosphatemia and AST elevation. Nearly all of the lab abnormalities had no clinical manifestations and did not require clinical intervention or change in study treatment


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Data from Pivotal Phase 2 FIREFLY-1 Trial December 22, 2022 data cutoff


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Tumor Response To Tovorafenib (DAY101) For All Patients With RANO-HGG Evaluable Lesions (n=69) – December 22, 2022 Data Cutoff Response (IRC) RANO-HGG1 Evaluable n=69 ORR (cCR + cPR + uPR), n (%) 46 (67%)* Clinical benefit rate, n (%) cCR, cPR/uPR, or SD cCR, cPR/uPR, or SD for 12 mo+ 64 (93%) 49 (71%) Best overall response, n (%) CR PR (includes 3 uPR) SD PD Not evaluable 4 (6%) 42 (61%) 18 (26%) 4 (6%) 1 (1%) All 3 patients with uPR remain on treatment as of May 23, 2023 Dec 22, 2022 data cutoff. Percents may not add to 100% due to rounding. Two of 69 patients are not shown in the waterfall plot; one patient passed away due to progressive disease (not related to tovorafenib) before the first imaging assessment and one did not receive T1 Gd+ follow-up imaging. *P<0.001 from two-sided exact binomial test to test null hypothesis of ORR=21% based on Bouffet et al.2 1 Wen PY, et al. J Clin Oncol. 2010;28(11):1963-1972. 2 Bouffet E, et al. J Clin Oncol. 2012;30(12):1358-1363. CBR, clinical benefit rate; cCR, confirmed completed response; cPR, confirmed partial response; CR, complete response; HGG, high-grade glioma; IRC, independent radiology review committee; MAPKi, mitogen-activated protein kinase inhibitor; MR, minor response; ORR, overall response rate; PD, progressive disease; PR, partial response; RANO, Response Assessment in Neuro-Oncology; SD, stable disease; uPR, unconfirmed partial response. There are 17 patients with stable disease of less than 12 months duration and at the time of the data cutoff, 11 remain on treatment.


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Tumor Response To Tovorafenib (DAY101) For All Patients With RAPNO-LGG Evaluable Lesions (n=69*) – December 22, 2022 Data Cutoff Response (IRC) RAPNO-LGG1 Evaluable n=69 ORR (cCR + cPR/uPR + cMR/uMR), n (%) 35 (51%) Clinical benefit rate, n (%) cCR, cPR/uPR, cMR/uMR, or SD cCR, cPR/uPR, cMR/uMR, or SD for 12mo+ 60 (87%) 36 (52%) Best overall response, n (%) CR PR (includes 4 uPR) MR (includes 4 uMR) SD PD# Not evaluable 0 (0%) 17 (25%) 18 (26%) 25 (36%) 8 (12%) 1 (1%) All 4 patients with uPR and 3 patients with uMR remain on treatment as of May 23, 2023 Dec 22, 2022 data cutoff. Percents may not add to 100% due to rounding. Two of 69 patients not shown in waterfall plot; one patient passed away due to progressive disease (not related to tovorafenib) before the first imaging assessment and one patient had visual progressive disease but no evaluable T2 measurements at the time of progression. *Pending adjudication. 1 Fangusaro J, et al. Lancet Oncol. 2020;21(6):e305-316. #PD for RAPNO-LGG was not used to determine treatment discontinuation; patients could continue treatment if there was no PD based on RANO-HGG per investigator’s assessment. CBR, clinical benefit rate; cCR, confirmed completed response; cMR, confirmed minor response; cPR, confirmed partial response; CR, complete response; HGG, high-grade glioma; IRC, independent radiology review committee; LGG, low-grade glioma; MAPKi, mitogen-activated protein kinase inhibitor; MR, minor response; ORR, overall response rate; PD, progressive disease; PR, partial response; RANO, Response Assessment in Neuro-Oncology; RAPNO, Response Assessment in Pediatric Neuro-Oncology; SD, stable disease; uMR, unconfirmed minor response; uPR, unconfirmed partial response. There are 28 patients with stable disease of less than 12 months duration and at the time of the data cutoff, 11 remain on treatment.


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Tumor Response To Tovorafenib (DAY101) For All Patients With RANO-LGG Evaluable Lesions (n=76) – December 22, 2022 Data Cutoff Response (IRC) RANO-LGG1 Evaluable n=76 ORR (cCR + cPR/uPR + cMR/uMR), n (%) 37 (49%) Clinical benefit rate, n (%) cCR, cPR/uPR, cMR/uMR, or SD cCR, cPR/uPR, cMR/uMR, or SD for 12mo+ 63 (83%) 39 (51%) Best overall response, n (%) CR PR (includes 8 uPR) MR (includes 2 uMR) SD PD# Not evaluable§ 0 (0%) 20 (26%) 17 (22%) 26 (34%) 11 (14%) 2 (3%) All 8 patients with uPR and 2 patients with uMR remain on treatment as of May 23, 2023 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 investigator’s assessment. §Two of 76 patients are not shown in the waterfall plot; one patient passed away due to progressive disease (not related to tovorafenib) before the first imaging assessment, and one patient with missing T1 Gd+ imaging at baseline was deemed NE at all timepoints but had a best SPPD decrease of 65% on T2 imaging. 1 van den Bent MJ, et al. Lancet Oncol. 2011;12(6):583-593. BL, baseline; CBR, clinical benefit rate; cCR, confirmed completed response; cMR, confirmed minor response; cPR, confirmed partial response; CR, complete response; HGG, high-grade glioma; IRC, independent radiology review committee; LGG, low-grade glioma; MAPKi, mitogen-activated protein kinase inhibitor; MR, minor response; ORR, overall response rate; PD, progressive disease; PR, partial response; RANO, Response Assessment in Neuro-Oncology; SD, stable disease; SPPD, sum of the products of perpendicular diameters; uMR, unconfirmed minor response; uPR, unconfirmed partial response. There are 27 patients with stable disease of less than 12 months duration and at the time of the data cutoff, 19 remain on treatment.


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Duration Of Tovorafenib (DAY101) Therapy For All Patients With RANO-HGG & RANO-LGG Evaluable Lesions – December 22, 2022 Data Cutoff RANO-HGG (n=69) RANO-LGG (n=76) As of the data cutoff, the median IRC-assessed DOR based on RANO-LGG criteria was 14.4 months (95% CI: 8.4, not estimable)* As of the data cutoff, the median IRC-assessed DOR based on RANO-HGG criteria was not yet reached (95% CI: 9.0, not estimable)* * * * Analysis for median time to response and median duration of response only included confirmed responses. BOR is shown; circles indicate start of response. PD for the purpose of treatment was based on RANO-HGG, not RANO-LGG. BOR, best overall response; HGG, high-grade glioma; LGG, low-grade glioma; PD, progressive disease; RANO, Response Assessment in Neuro-Oncology; DOR, duration of response; CI, confidence interval. Dec 22, 2022 data cutoff.


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Estimated BRAF-Altered pLGG Patient Population In The U.S. 1 Selt F, van Tilburg CM, Bison B, et al. Response to trametinib treatment in progressive pediatric low-grade glioma patients. J Neurooncol. 2020;149(3):499-510. doi:10.1007/s11060-020-03640-3. 2 Ryall S, Tabori U, Hawkins C. Pediatric low-grade glioma in the era of molecular diagnostics. Acta Neuropathol Commun. 2020;8(1):30. doi:10.1186/s40478-020-00902-z.  3 SEER US complete prevalence counts of patients aged under 25 with Brain and Other Nervous Systems tumors as of January 1, 2017. 4 CBTRUS, Qaddoumi et al 2009, Schreck et al 2019, ClearView Analysis. 5 US Census. Estimated annual incidence, estimated prevalence, and estimated recurrent/progressive total addressable patient population are Day One calculations based on publicly available data. 6 Source: Internal market research conducted by EpidStrategies, A Division of ToxStrategies, Inc. on behalf of Day One. An estimated 26,000 children/young adults are living with BRAF-altered (BRAF fusions or BRAF V600E mutations) pLGGs in the U.S. today1-5 Despite significant disease burden, many pLGGs undergo senescence when patients reach their 20s driving the need to both maximize tumor control while minimizing treatment-associated toxicities As a result, a large number of pLGG patients will undergo multiple lines of systemic therapy over the course of their disease Based on progression free survival curves modeled from published literature, the estimated addressable pool of recurrent or progressive pLGG patients is ~2,000-3,0006 per year at steady state Estimated BRAF-Altered Patients in the U.S. Prevalence of Systemically-Treated Patients Under 253,4 Recurrent/Progressive Total Addressable Patient Population per Year6 Incidence of Treatment-Eligible Frontline Patients4,5 ~26,000 ~2,000-3,000 ~1,100


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Key Takeaways From FIREFLY-1 Data And Next Steps Next Steps Priority review granted with PDUFA target action date April 30, 2024 Clinically meaningful data from FIREFLY-1 for pediatric patients with recurrent or progressive LGG harboring BRAF fusions or BRAF V600E mutations (“BRAF-altered”) 67% ORR by RANO-HGG (primary endpoint) 51% ORR by RAPNO-LGG (secondary endpoint) 53% ORR by RANO-LGG (exploratory endpoint) Deepening of responses observed in patients from December 2022 to June 2023 data cutoffs across all three assessment criteria Responses were observed in patients with either BRAF fusion or BRAF V600E mutations (“BRAF-altered”) Responses seen in a heavily-pretreated population where the majority (60%) of patients progressed on or after one or more prior MAPK inhibitors Safety and tolerability profile indicating monotherapy tovorafenib to be generally well-tolerated June 5, 2023 data cutoff.


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FIREFLY-2/LOGGIC Pivotal Phase 3 Trial of Tovorafenib (DAY101) in Frontline pLGG


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FIREFLY-2/LOGGIC Pivotal Phase 3 Trial Of Tovorafenib (DAY101) In Frontline pLGG 1:1 Randomization Tovorafenib, 420mg/m2 QW (not to exceed 600 mg) Investigator's choice of vincristine/carboplatin* or vinblastine Long-term follow-up (48 months) Stratified by Location of tumor Genomic alteration CDKN2A status Infant CHG diagnosis Non-resectable or sub-total resected LGG AND Requiring first-line systemic therapy N ≈ 400 Primary endpoint: ORR based on RANO-LGG criteria, assessed by blinded independent central review1 The ORR primary analysis is expected to occur ~12 months after the last patient randomized Key secondary endpoints: PFS and DoR by RANO criteria, ORR by RAPNO criteria Other secondary endpoints: changes in neurological and visual function, safety, and tolerability Key exploratory objectives: QoL and health utilization measures Randomized, global, registrational Phase 3 trial of monotherapy tovorafenib (DAY101) vs SoC chemotherapy Eligibility: Patients aged 6 months to <25 years with LGG harboring a RAF alteration and requiring first-line systemic therapy Tovorafenib (DAY101) available as tablets and pediatric-friendly liquid suspension Patients who progress after stopping tovorafenib (DAY101) may be re-challenged Patients who progress in the SoC arm during or post-treatment may cross-over to receive tovorafenib Endpoints Trial Design * COG or SIOPe-LGG regimen. Abbreviations: CHG, chiasmatic, hypothalamic glioma; DoR, duration of response; LGG, low-grade glioma; ORR, objective response rate; QoL, quality of life; QW, once weekly; SoC, standard of care. 1 Primary endpoint of FIREFLY-2 will be ORR by RANO-LGG (2017) following full approval by FDA on March 16, 2023 of dabrafenib with trametinib in pediatric patients with low-grade glioma with a BRAF V600E mutation who require systemic therapy based on a study with the same primary endpoint.


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FIRELIGHT-1 Phase 1b/2 Trials Evaluating Tovorafenib (DAY101) as a Combination with Pimasertib


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Pimasertib: Investigational Allosteric MEK1/2 Inhibitor With Demonstrated Activity In MAPK-Driven Solid Tumors Pimasertib is an investigational orally-bioavailable, selective, non-competitive MEK1/2 inhibitor in-licensed from Merck KGaA in February 2021 Extensive non-clinical and clinical development work through Phase 2, including a solid tumor trial in Japan and combinations with other MOAs Main AEs typical for all in-class allosteric MEK inhibitors (GI, CPK elevation, skin rash, visual disturbances) Nearly three-fold higher CNS penetration than other MEKi inhibitors (trametinib or selumetinib) Pimasertib showed monotherapy clinical activity, including an improvement in median PFS versus dacarbazine in NRAS mutant melanoma Combination with tovorafenib (DAY101) and other targeted therapies may unlock the full value of pimasertib in advanced solid tumors Sources: Pimasertib Investigator Brochure, v12, 2019; de Gooijer et al., Int J Cancer, 2018; Shaw et al., AACR LB-456, 2012; Lebbe et al., Cancers, 2020.


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Vertical MAPK Pathway Inhibition With Tovorafenib (DAY101) And Pimasertib May Unlock Potential Synergy For Adult Solid Tumors Type II RAFi + MEKi is synergistic in BRAF fusion melanoma PDX model ex vivo (internal data) Sensitivity of KRAS Q61 mutant cells to pimasertib is enhanced when cells are treated with the type II BRAF inhibitor BGB-283 (Yuan et al., Mol Onc 2020) Tovorafenib (DAY101) + MEK inhibitor is synergistic in KRAS G12C and Q61 mutant tumor cells (Venetsanakos et al., 2021 AACR poster presentation) B C Type II RAFi + MEKi KRAS or NRAS mutant Proliferation, survival RAF/ MEK/ERK RAL PI3K/m TOR A Type II RAFi + MEKI BRAF non-V600 mutant Targeting multiple nodes of MAPK pathway will drive deeper and more durable response Non V600 BRAF dimers are effectively inhibited by type II RAFi , but not type I BRAFi Proliferation, survival MEK ERK


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Tovorafenib (DAY101) / Pimasertib Combination In Solid Tumors (FIRELIGHT-1) Pre-identified patients with advanced solid tumors and available clinical molecular profiling information. Phase 1b Tumors with MAPK pathway alterations *Additional biomarker-selected cohorts may be pursued based on developing data Phase 2* NRASmut Selected tumors BRAF fusion selected tumors BRAF Class 1 (non-E/K) and Class 2 mutant tumors DAY101 + Pimasertib until disease progression3 Safety Follow Up Phase 1b: PK, PD and Safety, MTD/RP2D Phase 2: Efficacy (ORR, DOR) Combination dose escalation, global phase 1b/2 trial2 Phase 1b, BOIN (adaptive), n = 10/cohort (approximately) Phase 2, Simon 2-stage, n = 25/cohort (approximately) Eligibility: Patients aged 12 years and older, dose escalation will be performed in advanced solid tumor patients with any MAPK alteration. Expansion cohorts will focus on indications with a potential path to accelerated approval Endpoints Trial Design1 Abbreviations: BOIN, Bayesian Optimal Interval Design; BRAF, B-Raf proto-oncogene, serine/threonine kinase; MAPK, mitogen-activated protein kinase; NRAS, neuroblastoma rat sarcoma viral oncogene. 1Umbrella master study – DAY101-102 (main protocol) DAY101 and MAPK pathway aberration, Sub-study 1 monotherapy (DAY101-102a), Sub-study 2 MEK combo (DAY101-102b).2Intend to open U.S. and ex-U.S. clinical sties. 3DAY101 + Pimasertib until disease progression, intolerable toxicity, withdrawal of consent, or death


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Summary


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Financial Summary: DAWN $ Millions Nine Months Ended 9/30/23 Nine Months Ended 9/30/22 R&D Expense $93.2 $59.6 G&A Expense $53.4 $44.6 Net Loss $134.4 $102.1 Projected cash runway into 2026 FIREFLY-1: Pivotal Phase 2 clinical trial of tovorafenib (DAY101) Initiated rolling NDA1 in May 2023 Topline data presented in September 2023 FDA acceptance of NDA and priority review granted in October 2023 PDUFA target action date of April 30, 2024 FIREFLY-2/LOGGIC: Pivotal Phase 3 clinical trial of tovorafenib (DAY101) in newly diagnosed pLGG First patient dosed in March 2023 Cash, cash equivalents and short-term investments as of September 30, 2023: $405.5 million (no debt) ~87.0 million shares of common stock outstanding as of November 1, 2023 All financial and share information is unaudited. 1NDA data set includes analysis of primary (ORR by RANO-HGG) and secondary (ORR by RAPNO, PFS) efficacy endpoints, safety, and exploratory analyses (including ORR by RANO-LGG).


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Next Steps FIREFLY-1 Initiated rolling NDA in May 2023 New topline data presented in September 2023 FDA acceptance of NDA and priority review granted in October 2023 PDUFA target action date of April 30, 2024 FIREFLY-2 Advance tovorafenib as a frontline therapy for patients with pLGG Currently activating sites and enrolling patients Commercial Continue investment in market and launch preparation activities Business Development Research collaboration and license agreement for preclinical program targeting VRK1 Further investment in business development activities to expand our multiple asset portfolio FIRELIGHT-1 Evaluate tovorafenib in combination in adolescent and adult populations


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Appendix


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Duration Of Tovorafenib (DAY101) Therapy For All Patients With RANO-HGG Evaluable Lesions (n=69) 11/17 patients with stable disease <12 months remain on treatment as of data cutoff Partial response Complete response Progressive disease Discontinuation due to AE Death Ongoing treatment Discontinued treatment Follow-up after discontinuation of treatment BRAF V600E mutation Prior MEK inhibitor therapy Prior BRAF inhibitor therapy 10.8 MONTHS Median duration of treatment* 2.8 MONTHS Median time to response* * Analysis for median time to response and median duration of treatment only included confirmed responses. HGG, high-grade glioma; RANO, Response Assessment in Neuro-Oncology. Dec 22, 2022 data cutoff.


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All RANO-LGG Unconfirmed PR Patients Continue On Treatment With Demonstrable Deepening Of Response (n=8) Responses for Patients with Unconfirmed Partial Response by RANO-LGG Percent Change from Baseline (%) Months from Baseline SD MR PR CR All 8 patients with unconfirmed partial response by RANO-LGG remain on treatment as of May 23, 2023 Spider plot for SPPD – baseline and after treatment (RANO-LGG by IRC) – unconfirmed PR patients EOT status based on May 23, 2023 EDC data. Individual patient response data is current as of the data cutoff of December 22, 2022; treatment status data is current as of May 23, 2023.


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Nearly Half Of Patients With Best Response Of PD By RANO-LGG Have Tumor Stabilization And Response With Continued Treatment (n=11) 5/11 patients with best response of PD by RANO-LGG remain on treatment as of May 23, 2023 Ongoing treatment Discontinued treatment Individual patient response data is current as of the data cutoff of December 22, 2022; treatment status data is current as of May 23, 2023.


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Tovorafenib (DAY101) Safety Data (n=136) Preferred term, n (%) Treatment-emergent AEs Treatment-related AEs Any grade Grade ≥3 Any grade Grade ≥3 Any AE 136 (100) 68 (50) 133 (98) 47 (35) Hair color changes 96 (71) - 96 (71) - Fatigue 68 (50) 4 (3) 54 (40) 4 (3) Vomiting 59 (43) 3 (2) 24 (18) 3 (2) Rash maculo-papular 56 (41) 10 (7) 51 (38) 10 (7) Headache 53 (39) 1 (1) 27 (20) - Pyrexia 43 (32) 2 (1) 15 (11) 1 (1) Nausea 40 (29) - 21 (15) - Dry skin 39 (29) - 34 (25) - Dermatitis acneiform 37 (27) 1 (1) 36 (26) 1 (1) Constipation 36 (26) - 28 (21) - Decreased appetite 35 (26) 4 (3) 25 (18) 3 (2) Epistaxis 34 (25) - 22 (16) - The vast majority of treatment-emergent AEs were Grade 1 or 2 39 patients (29%) required dose modifications due to treatment-related AEs Dose interruptions were brief, with the median time of dose interruption being 2 weeks 5 patients (4%)* discontinued due to AE, with 4 patients (3%) discontinuing due to treatment-related AEs The most commonly reported lab abnormalities were CPK elevation, anemia, hypophosphatemia, and AST elevation Nearly all had no clinical manifestations and did not require clinical intervention or change in study treatment Dec 22, 2022 data cutoff. Table shows treatment-emergent AEs with frequency ≥25% of any grade. Rash erythematous treatment-emergent: any grade, 14 (10%); grade ≥3 1 (1%); treatment-related: any grade, 14 (10%), grade ≥3 1 (1%). *One patient had 2 events (shunt malfunction [not related to tovorafenib] and tumor hemorrhage [related to tovorafenib]). AEs, adverse events.


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Diagnostic biopsy Months A 7-years-old female child with an optic pathway glioma, with very poor vision, entropion, folliculitis, eczema, mouth ulceration and xerosis Case Study: Activity Of Tovorafenib (DAY101) In KIAA1549-BRAF Fusion Optic Pathway Glioma PR 1L: Vincristine/carboplatin Best response SD 2L: Trametinib Best response PD 3L: Tovorafenib -24 -18 -12 -6 0 6 -30 -36 PR (-58%) and improvement in vision reported at cycle 3 AEs included grade 3 erythematous rash requiring dose interruption and dose reduction (400 mg QW to 300 mg QW in cycle 1), and grade 2 eczema and maculopapular rash Patient continues to receive weekly tovorafenib Tumor kinetics (RANO) Tovorafenib After 6 cycles Baseline Apr 14, 2022 data cutoff. Tovorafenib is an investigational agent. Safety and efficacy have not been established by any health authority.


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Months An 8-years-old female child with a posterior fossa pilocytic astrocytoma, eczema, nausea and constipation Case Study: Activity Of Tovorafenib (DAY101) In KIAA1549-BRAF Fusion Posterior Fossa Pilocytic Astrocytoma Suboccipital craniotomies 2L: Carboplatin/vincristine Best response PR PR 3L: Vinblastine Best response SD -84 -48 -36 -24 -12 0 12 -72 4L: Trametinib Best response SD 5L: Tovorafenib -60 1L: Carboplatin Best response PD After 6 cycles After 3 cycles After 9 cycles Tumor kinetics Tovorafenib Baseline PR (-69%) at cycle 3 with 500 mg QW tovorafenib, with a deepening of response (80% and 91% in cycles 6 and 9, respectively) over time AEs included grade 2 decrease in neutrophil count, pustular rash, and upper respiratory infection Patient continues to receive weekly tovorafenib Apr 14, 2022 data cutoff. Tovorafenib is an investigational agent. Safety and efficacy have not been established by any health authority.


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Months A 9-year-old female child with deep midline BRAF V600E-mutant astrocytoma with precocious puberty -60 Case Study: Activity Of Tovorafenib (DAY101) In BRAF V600E Mutation Deep Midline Astrocytoma PR -48 -36 -24 -12 0 12 2L: Dabrafenib Best response PR 3L: Tovorafenib 1L: Carboplatin/vincristine Best response PR Subtotal resection Tumor kinetics Tovorafenib After 6 cycles After 3 cycles Baseline PR (-74%) at cycle 3, with a deepening of response (-94%) at cycle 6 AEs included grade 3 maculopapular rash and increased CPK, requiring drug interruption and dose reduction (500 mg QW to 400 mg QW in cycle 1) Tovorafenib dose was re-escalated back to 500 mg QW in cycle 4; patient continues on treatment Apr 14, 2022 data cutoff. Tovorafenib is an investigational agent. Safety and efficacy have not been established by any health authority.


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Case Study: Activity Of Tovorafenib (DAY101) In KIAA1549-BRAF Fusion Optic Pathway Glioma Tumor kinetics Trametinib Tovorafenib Months -48 -36 -24 -12 0 12 -60 24 VC Binimetinib PR Initiated treatment with tovorafenib 400 mg/QW following 3 prior therapies, including binimetinib and trametinib, which were discontinued due to PD At cycle 3, PR (-88%) per RANO-HGG, and MR (-32% and -40%) per RAPNO-LGG and RANO-LGG, respectively Sustained improvements in visual acuity reported; logMAR change 0.2 → 0 PD criteria met (-94% to -91%) with RANO-HGG at cycle 15; continued treatment as investigator deemed no radiographic progression with subsequent reduction in target lesion (-97%) AEs were G2 (drug eruption, elevated CPK) and G1 (hair color change, paronychia, growth retardation) 8-year-old boy with relapsed pilomyxoid astrocytoma of the optic pathway, with visual loss in right eye, visual field loss in left eye, fatigue, intermittent nausea/vomiting, intermittent headaches, anorexia, and temperature regulation disorder T1 + C (baseline and post-cycle 3) T2 (baseline and post-cycles 3 & 12) Dec 22, 2022, data cut-off. AEs, adverse events; C, contrast; CPK, creatine phosphokinase; G, grade; HGG, high-grade glioma; LGG, low-grade glioma; logMAR, Logarithm of the Minimum Angle of Resolution; MR, minor response; PD, progressive disease; PR, partial response; QW, once weekly; RANO, Response Assessment in Neuro-Oncology; RAPNO, Response Assessment in Pediatric Neuro-Oncology; VC, vincristine-carboplatin.


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Collaboration between Day One and the LOGGIC consortium, internationally recognized experts in pLGG research Coupled with the LOGGIC-CORE molecular diagnostic program Worked jointly on the study design and discussions with the U.S. and EU regulatory authorities FIREFLY-2/LOGGIC: Pivotal Phase 3 Study Of Tovorafenib (DAY101) In Newly Diagnosed pLGG ~5 Sites Approximately 100 potential sites (~65 from the LOGGIC consortium) ~20 Sites ~65 Sites ~10 Sites


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Results From Independent Radiology Review Of PNOC014 RAPNO: Response assessment for pediatric neuro-oncology (exploratory) RANO-HGG: Response assessment for neuro-oncology-high grade glioma Volumetric image analysis (exploratory) Best response from baseline Date of data cutoff: 02 JAN 2020. Wright K et. al. Neuro Oncology Abstract CTNI-19. 2020


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Multiple Rapid, Deep And Durable Responses Observed Following Initiation Of Tovorafenib (DAY101) Treatment Of pLGG Patients In PNOC014 Growth kinetics of Target Lesions from Screening Date of data cutoff: 02 JAN 2020. Adapted from Wright K et. al. Neuro Oncology Abstract CTNI-19. 2020. Fangusaro J et al. Lancet Oncol 2019


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Drug-related Adverse Events Observed for Tovorafenib (DAY101) in PNOC014 Showed Favorable Safety and Tolerability Profile in pLGG Toxicities Grade 1-2 Grade 3 Grade 4 Anemia 6 (67%) Hypophosphatemia 4 (44%) Fatigue 5 (55%) Rash 8 (89%) Achromotrichia 7 (78%) Pruritis 6 (67%) Photosensitivity 1 (11%) Nevus 7 (78%) Alopecia 3 (34%) Epistaxis 2 (22%) Dry skin 3 (34%) Myalgias/arthralgias 3 (34%) Anorexia 2 (22%) Cheilitis 3 (34%) Hypermagnesemia 1 (11%) Bleeding gums 1 (11%) Increased AST 4 (44%) Nausea/vomiting 3 (33%) CPK elevation 1 (11%) Weight loss 2 (22%) DAY101 AE summary Most common toxicity: skin AEs reversible and all manageable Single, reversible Grade 3 event No Grade 4 AEs No dose reductions (vs. 40% of patients on selumetinib montherapy required dose reductions) Drug-related AEs for Tovorafenib (DAY101) Toxicities Grade 1-2 Grade 3 Grade 4 Increased ALT 20 (40%) 1 (2%) CPK elevation 34 (68%) 5 (10%) Diarrhea 27 (54%) 2 (4%) Decreased ejection fraction 19 (38%) 1 (2%) Gastric haemorrhage 1 (2%) Headache 14 (28%) 1 (2%) Decreased lymphocyte count 19 (38%) 1 (2%) Neutropenia 14 (28%) 3 (6%) Paronychia 19 (38%) 3 (6%) Rash (acneiform) 29 (58%) 2 (4%) Rash (maculopapular) 26 (52%) 5 (10%) Skin infection 7 (14%) 1 (2%) Tooth infection 1 (2%) Weight gain 5 (10%) 1 (2%) Vomiting 22 (44%) Nausea 21 (42%) Increased AST 25 (50%) Anemia 28 (56%) Pruritis 10 (20%) Dyspnea 30 (60%) Drug-related AEs for selumetinib Date of DAY101 data cutoff: 02 JAN 2020; Wright K et. al. Neuro Oncology Abstract CTNI-19. 2020; Fangusaro J et al. Lancet Oncol 2019