On May 11, 2023 Harpoon Therapeutics, Inc. (Nasdaq: HARP), a clinical-stage immuno-oncology company developing novel T cell engagers, reported its financial results for the first quarter ended March 31, 2023 and provided a corporate update (Press release, Harpoon Therapeutics, MAY 11, 2023, View Source [SID1234631596]).
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"Harpoon is executing its business plan in 2023 with a strengthened balance sheet, advancing multiple programs based on the TriTAC platform, and ProTriTAC IND candidates ready for further development," said Julie Eastland, President and Chief Executive Officer of Harpoon Therapeutics. "Following the $25 million preferred equity financing in March 2023, we have the financial strength to fund current operations into the second half of 2024. Additionally, we expect to see a positive impact on our cash burn over the course of the year from the restructuring implemented in the fourth quarter of last year. We also anticipate completion of enrollment for two of our Phase 1 clinical programs, HPN217 and HPN328, and achievement of key data milestones this year. Our clinical and leadership teams remain focused on advancing a rich pipeline of next-generation T cell engagers to address a broad patient population with unmet needs in both solid tumor and blood cancer indications."
Corporate Update / Recent and Upcoming Highlights
Tri-specific T cell Activating Construct (TriTAC) Platform
HPN217 (BCMA) Phase 1 trial for relapsed, refractory multiple myeloma
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Interim results reported at the 64th American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting (cut-off of October 17, 2022) demonstrated continued evidence of clinical activity with 77% (10/13) ORR observed in the two highest target dose levels (12 and 24 mg).
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Overall low incidence of cytokine release syndrome (CRS) across the patient population studied to date.
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Completion of Phase 1 dose exploration is expected in the first half of 2023, with identification of a recommended Phase 2 dose(s) expected by the end of 2023.
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Data presentation anticipated in the second half of 2023.
HPN328 (DLL3) Phase 1/2 trial in small cell lung cancer (SCLC) and neuroendocrine cancers
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Observations in the monotherapy cohorts, as of February 2023, included early signs of anti-tumor activity, with two confirmed partial responses per RECIST in patients with SCLC.
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Phase 1/2 dose and schedule optimization trial ongoing with monotherapy cohorts enrolling at the 24 mg target dose.
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Enrollment in combination therapy of HPN328 with atezolizumab (Tecentriq) in patients with SCLC, as part of the Phase 1/2 dose escalation trial, is anticipated to begin in the second half of 2023.
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Phase 1 dose exploration is expected to complete in the second half of 2023, including the identification of a recommended Phase 2 dose(s) in the monotherapy setting by the end of 2023.
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Data presentation anticipated in the second half of 2023.
ProTriTAC
HPN601 (EpCAM)
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HPN601 is Harpoon’s first conditionally active T cell engager based on the ProTriTAC platform. EpCAM is expressed in a broad range of solid tumors, potentially enabling HPN601 to address multiple indications with high unmet medical need.
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IND filing timeline to enable a Phase 1 dose exploration study dependent on resource allocation.
Two additional candidates
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Two new candidates for potential IND-enabling studies from the ProTriTAC platform have been identified against the targets trophoblast cell surface antigen 2 (TROP2) and Integrin-ß6 (ITGB6).
TriTAC-XR
The proprietary TriTAC-XR extended-release T cell engager platform is designed to minimize on-target CRS, a characteristic of many T cell engagers that can lead to dose limiting toxicities and can reduce the efficacy of these potent anti-tumor drugs.
AACR 2023 – Five Preclinical Posters Presented
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HPN217: Poster presented on April 18, 2023:
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"Anti-tumor activity of HPN217, a BCMA-targeting tri-specific T cell engager, is enhanced by y-secretase inhibitors in preclinical models"
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In preclinical mouse models, y-secretase inhibitors increased the potency of HPN217 in vitro in multiple cell lines.
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Combination therapy with 1mg/kg LY-3039478 and a subtherapeutic dose of 4ug/kg HPN217 led to decreased tumor burden and increased survival in a disseminated MOLP8 xenograft compared to either monotherapy alone.
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HPN328: Two posters presented on April 18, 2023:
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"Long-term anti-tumor immunity induced by HPN328, a DLL3-targeting tri-specific, half-life extended T cell engager, in a preclinical immunocompetent mouse model"
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These results suggest that HPN328 can induce epitope spreading and prolonged anti-tumor immunity, with an increase in memory T cells, suggesting a novel mechanism for its activity and efficacy in vivo.
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These findings suggest that long-term anti-tumor immunity induced by HPN328 can potentially lead to more durable anti-tumor responses in cancer patients
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"Anti-tumor activity of HPN328, a DLL3-targeting tri-specific, half-life extended T cell engager, is enhanced by combining with an anti-PD-L1 antibody in an immunocompetent mouse model"
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These results demonstrate the utility of combining anti-PD-L1 antibodies to enhance the anti-tumor activity of HPN328 and further supports investigation of this combination approach in patients.
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Clinical studies of HPN328 in combination with atezolizumab are planned.
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ProTriTAC: Two posters presented on April 17, 2023 introducing new candidates for IND-enabling studies:
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"TROP2 ProTriTAC, a protease-activated T cell engager prodrug targeting TROP2 for the treatment of solid tumors"
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"ITGB6 ProTriTAC, a protease-activated T cell engager prodrug targeting Integrin-ß6 for the treatment of solid tumors"
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Both data sets support further investigation of Harpoon’s conditionally active next-generation T cell engager platform, ProTriTAC, with demonstrated therapeutic potential in a broad range of TROP2- and ITGB6-expressing solid tumors.
Corporate Update
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$25 million preferred equity financing closed in March 2023, extending cash runway into the second half of 2024.
First Quarter 2023 Financial Results
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Harpoon ended the first quarter of 2023 with $61.4 million in cash and cash equivalents compared to $53.1 million as of December 31, 2022. Following the $25.0 million preferred equity financing and year to date ATM sales, cash and cash equivalents are expected to fund current operations into the second half of 2024.
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Revenue for the quarter ended March 31, 2023 was $8.6 million, compared to $5.9 million for the first quarter ended March 31, 2022. The increase in revenue was primarily due to revenue recognized in first quarter 2023 for research and development services performed on the fourth target under Harpoon’s Restated Collaboration Agreement with AbbVie, and an increase in revenue recognized related to Harpoon’s Development and Option Agreement with AbbVie for research and development services performed.
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Research and development (R&D) expense for the quarter ended March 31, 2023 was $15.2 million, reduced from $20.8 million during the first quarter ended March 31, 2022. The decrease primarily arose from lower personnel-related costs due to corporate restructuring implemented in November 2022 and lower clinical and development costs due to the wind down of the HPN424 and HPN536 programs.
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General and administrative (G&A) expense for the quarter ended March 31, 2023 decreased to $4.2 million, compared to $5.4 million for the first quarter ended March 31, 2022. The decrease was primarily attributable to lower personnel-related expenses, lower legal costs, and lower professional service fees to support Harpoon’s operations.
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Net loss for the first quarter ended March 31, 2023 was $11.3 million, improved from $20.3 million for the first quarter ended March 31, 2022.