Press Release

PTK7 Expression Remained Stable Following Standard-of-Care Therapies, Supporting Its Relevance as
a Target in Second- or Later-Line EGFR NSCLC

Findings Reinforce the Scientific Rationale for HWK-007, Whitehawk's Next-Generation PTK7-Directed
ADC Currently in Phase 1 Development

MORRISTOWN, N.J., Sept. 13, 2026 /PRNewswire/ -- Whitehawk Therapeutics, Inc. (Nasdaq: WHWK), a clinical-stage oncology therapeutics company applying advanced technologies to established tumor biology to efficiently develop improved antibody drug conjugate (ADC) cancer treatments, today announced the presentation of two real-world analyses supporting protein tyrosine kinase 7 (PTK7) as a durable and clinically relevant ADC target in patients with pretreated, EGFR wild-type non-small cell lung cancer (NSCLC). The data will be presented at the IASLC 2026 World Conference on Lung Cancer (WCLC) hosted by the International Association for the Study of Lung Cancer, taking place September 12-15, 2026, in Seoul, Republic of Korea.

In tumor samples from patients with EGFR wild-type lung adenocarcinoma, PTK7 expression remained largely stable following standard-of-care (SoC) treatments, including chemotherapy and immunotherapy, and demonstrated less treatment associated variation than several other ADC targets in late-stage development. PTK7 expression was also generally consistent regardless of the presence or absence of other actionable genomic alterations (AGA). These findings indicate PTK7 remains available for targeted ADCs for patients that have progressed through multiple lines of SoC therapy and across clinically relevant subgroups.

A separate analysis of patients with advanced EGFR wild-type lung adenocarcinoma found that real-world overall survival was not impacted based on PTK7-expression, supporting PTK7 as a target-engagement biomarker for ADC payload delivery independent of prognosis in NSCLC.

"The development strategy for our PTK7-directed ADC, HWK-007, is grounded in understanding not only where PTK7 is expressed, but also how that expression behaves in a real-world treatment setting," said Margaret Dugan, MD, Chief Medical Officer of Whitehawk Therapeutics. "The stability of PTK7 expression after standard of care therapies, in particular compared to other therapies in late-stage development, add important translational context as we evaluate HWK-007 in patients with EGFR wild-type NSCLC."

Key Findings:

Durable and Treatment-Agnostic PTK7 Expression in EGFR Wild-Type Lung Adenocarcinoma Supports Targeted ADC Development

• PTK7 expression remained largely stable following standard-of-care immunotherapy, chemotherapy, chemoimmunotherapy and tyrosine kinase inhibitor treatment, suggesting that the target may remain available for PTK7-directed therapy after prior treatment.
• Stable PTK7 expression is also observed in paired tumor samples.
• PTK7 demonstrated less treatment-associated variation than several late-stage ADC targets, including MET, PD-L1 and ITGB6.
• PTK7 expression was generally consistent across tumors with or without other AGA, including KRAS G12C, ALK and MET alterations, suggesting relevance of PTK7 as an ADC target across both AGA+ and AGA- NSCLC subgroups.

Association Between PTK7 Expression and Real-World Survival in Pretreated Patients With EGFR Wild-Type Lung Adenocarcinoma

• PTK7 expression was not independently associated with real-world overall survival or progression-free survival in patients with advanced EGFR wild-type lung adenocarcinoma receiving second- or later-line therapy, supporting PTK7 as a target-engagement biomarker rather than a marker of prognosis.
• Clinical outcomes were driven primarily by established prognostic factors, including Eastern Cooperative Oncology Group performance status and extent of prior therapy.
• PTK7-low tumors were enriched for KEAP1 and STK11 alterations, suggesting biological heterogeneity of EGFR wild-type NSCLC.

"Understanding whether a therapeutic target remains present after prior treatment is particularly important in advanced lung cancer, where patients often receive multiple lines of therapy," said Aaron E. Lisberg, MD, Associate Professor of Medicine at the David Geffen School of Medicine at UCLA. "The stability of PTK7 expression across standard treatments and clinically relevant molecular subgroups supports further investigation of PTK7-directed ADCs in patients with previously treated EGFR wild-type lung adenocarcinoma."

Poster Presentation Details:

Title: Durable and Treatment-Agnostic PTK7 Expression in EGFR Wild-Type Lung Adenocarcinoma Supports Targeted ADC Development
Poster: P2.241
Presenter: Aaron E. Lisberg, MD, University of California Los Angeles, Los Angeles, CA, USA
Date & Time: Monday, September 14, 2026, at 10:30 AM KST

Title: Association Between PTK7 Expression and Real-World Survival in Pretreated Patients With EGFR Wild-Type Lung Adenocarcinoma
Poster: P2.147
Presenter: Grace Dy, MD, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
Date & Time: Monday, September 14, 2026, at 10:30 AM KST

HWK‑007 is PTK7-directed, next-generation ADC being evaluated in an ongoing Phase 1 clinical trial in patients with non-squamous, EGFR wild-type NSCLC, platinum-resistant ovarian cancer and endometrial cancer (NCT07444814). 

These analyses were conducted as part of a previously announced collaboration between Whitehawk and Tempus AI. The posters will be accessible on the Presentations page of the Investors & News section of the Company's website at www.whitehawktx.com.

About Whitehawk Therapeutics
Whitehawk Therapeutics is a clinical-stage oncology therapeutics company applying advanced technologies to established tumor biology to efficiently develop improved cancer treatments. Whitehawk's portfolio includes HWK-007, HWK-016 and HWK-206, ADCs engineered to overcome the limitations of first-generation predecessors to deliver a meaningful impact for patients with difficult-to-treat cancers. These assets are in-licensed from WuXi Biologics under an exclusive development and global commercialization agreement.

Whitehawk's underlying ADC platform leverages CPT113 as the core linker-payload technology, enhanced with its proprietary Carbon Bridge Cysteine Re-pairing (CBCR) bioconjugation process to support improved stability and therapeutic index. More information on the Company is available at www.whitehawktx.com and connect with us on LinkedIn. Any references to the Company's website or other online resources are provided solely for convenience and are not incorporated by reference into this press release. Investors should rely only on the information contained in this press release and the Company's filings with the Securities and Exchange Commission.

Forward-Looking Statements
This press release contains certain forward-looking statements regarding the business of Whitehawk Therapeutics that are not a description of historical facts within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements are based on the Company's current beliefs and expectations and may include, but are not limited to, statements relating to the potential therapeutic value and market opportunity for HWK-007 and  expectations regarding the beneficial characteristics, design features and the potential targeted markets with respect to HWK-007. Actual results could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation, uncertainties associated with preclinical and clinical development of HWK-007 .

Additional risks and uncertainties that could cause actual outcomes and results to differ materially from those contemplated by the forward-looking statements are included in the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2025, including under the caption "Item 1A. Risk Factors," and in Whitehawk's subsequent Quarterly Reports on Form 10-Q, and elsewhere in Whitehawk's reports and other documents that Whitehawk has filed, or will file, with the SEC from time to time and available at www.sec.gov.

All forward-looking statements in this press release are current only as of the date hereof and, except as required by applicable law, Whitehawk undertakes no obligation to revise or update any forward-looking statement, or to make any other forward-looking statements, whether as a result of new information, future events or otherwise. All forward-looking statements are qualified in their entirety by this cautionary statement. This cautionary statement is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995.

Contact:
IR@whitehawktx.com

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SOURCE Whitehawk Therapeutics, Inc.