Harpoon Therapeutics Announces First Patients with Small Cell Lung Cancer Dosed in HPN328 Combination Cohort

SOUTH SAN FRANCISCO, Calif., Sept. 15, 2023 (GLOBE NEWSWIRE) -- Harpoon Therapeutics, Inc. (Nasdaq: HARP), a clinical-stage immuno-oncology company developing novel T cell engagers, today announced dosing of the first patients with small cell lung cancer (SCLC) in an ongoing Phase 1/2 trial of HPN328, a DLL3 targeting TriTAC^®, in combination with atezolizumab (Tecentriq^®). Harpoon previously entered a Master Clinical Supply Agreement with F. Hoffmann-La Roche for the supply of atezolizumab. Under this agreement, Harpoon is the sponsor of the trial and Roche will supply atezolizumab. This announcement is being made in conjunction with Harpoon’s investor event, “DLL3 Market Opportunity and KOL Discussion of HPN328,” held virtually and in person today in New York beginning at 8 a.m. ET.

“Dosing the first patients in these combination cohorts for HPN328 with atezolizumab in patients with SCLC marks a significant milestone for this clinical program,” said Luke Walker, M.D., Chief Medical Officer for Harpoon Therapeutics. “Building on the strength of our Phase 1 data, we remain committed to realizing the full potential of HPN328 as an important treatment option for patients with SCLC and other neuroendocrine tumors across early and late lines of therapy.”

About the HPN328 + Atezolizumab Combination Cohort

Previously treated extensive stage SCLC patients enrolled in these combination cohorts will be dosed with HPN328 administered once every 2 weeks (Q2W) by IV infusion during each 28-day cycle. Atezolizumab will be administered once every 4 weeks (Q4W) by IV infusion on day 1 of each 28-day cycle. Primary outcome measures will include frequency and severity of treatment emergent adverse events (TEAEs), number and severity of dose limiting toxicities (DLTs), and pharmacokinetic parameters. Secondary outcome measures will include objective response rate (ORR), progression-free survival (PFS), overall survival (OS), duration of response (DOR), and anti-drug antibody (ADA) formation. Enrollment in the combination cohorts has been initiated at the 12 mg Q2W HPN328 dose level, and escalation is planned per protocol dependent on data, with initial results from these combination cohorts expected in 2024. Separately, HPN328 interim Phase 1 monotherapy data will be presented at the European Society for Medical Oncology (ESMO) held on October 20-24, 2023.

Webcast Information for “DLL3 Market Opportunity and KOL Discussion of HPN328”

• The webcast will begin at 8 a.m. ET and can be accessed using this link:
  
  
• A live webcast and archived replay of the event will be accessible on the Investor Relations page of the Harpoon website at .

About Harpoon Therapeutics

Harpoon Therapeutics is a clinical-stage immuno-oncology company developing a novel class of T cell engagers that harness the power of the body’s immune system to treat patients suffering from cancer and other diseases. T cell engagers are engineered proteins that direct a patient’s own T cells to kill target cells that express specific proteins, or antigens, carried by the target cells. Using its proprietary Tri-specific T cell Activating Construct (TriTAC^®) platform, Harpoon is developing a pipeline of novel TriTACs initially focused on the treatment of solid tumors and hematologic malignancies. Harpoon has also developed a proprietary ProTriTAC™ platform, which applies a prodrug concept to its TriTAC platform to create a therapeutic T cell engager that remains inactive until it reaches the tumor. Harpoon’s third proprietary technology platform, extended release TriTAC-XR, is designed to mitigate cytokine release syndrome. For additional information about Harpoon Therapeutics, please visit and follow us on and .

Tecentriq^® (atezolizumab) is a registered trademark of F. Hoffmann La-Roche Ltd.

Cautionary Note on Forward-looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as “continue,” “will” and similar expressions (as well as other words or expressions referencing future events, conditions, or circumstances) are intended to identify forward-looking statements. These forward-looking statements are based on Harpoon Therapeutics’ expectations and assumptions as of the date of this press release. These forward-looking statements involve risks and uncertainties that could cause Harpoon Therapeutics’ clinical development programs, future results, or performance to differ significantly from those expressed or implied by the forward-looking statements. Forward-looking statements in this press release include, but are not limited to, statements relating to the effects of advancing Harpoon Therapeutics’ platforms, the company’s future business growth and partnerships, expectations regarding strengthening the company’s business team, and other statements that are not historical fact. These and other factors that may cause Harpoon Therapeutics’ actual results to differ from those expressed or implied in the forward-looking statements in this press release are discussed in Harpoon Therapeutics’ filings with the U.S. Securities and Exchange Commission, including under “Risk Factors” in Harpoon Therapeutics’ quarterly report on Form 10-Q for the quarter ended June 30, 2023, and future filings by Harpoon Therapeutics. Except as required by law, Harpoon Therapeutics assumes no obligation to update any forward-looking statements contained herein to reflect any change in expectations, even as new information becomes available.

Contact:

ICR Westwicke

Robert H. Uhl

Managing Director

858-356-5932