FDA Grants Orphan Drug Designation to BCMA-targeting Specific T Cell Activating Recombinant Protein (HPN217) for Patients with Multiple Myeloma

FDA Grants Orphan Drug Designation to BCMA-targeting Specific T Cell Activating Recombinant Protein (HPN217) for Patients with Multiple Myeloma TrialsiteN

The U.S. Food and Drug Administration decided to open the Orphan Drug Designation (ODD) to an investigational drug for the treatment of patients with multiple myeloma. A B-cell maturation antigen BCMA-targeting specific T cell activating recombinant protein product known as HPN217, the ODD opens up research for Harpoon Therapeutics as to whether this drug is safe and effective for patients with multiple myeloma.

What is the FDA Orphan Drug Designation?

This program offered by the U.S. FDA provides orphan status to drugs defined as those intended for the safe and effective treatment, diagnosis or prevention of rare disease that affect fewer than 200,000 people in the United States. ODD qualifies the sponsor, such as Harpoon Therapeutics, for certain development incentives, including tax credits for qualified clinical testing, prescription drug user fee exemptions and seven-year marketing exclusivity upon FDA approval.

What is the drug?

HPN217, a tri-specific T cell activating recombinant protein construct (TriTAC®) targets B-cell maturation antigen (BCMA), a well validated antigen expressed on malignant multiple myeloma cells. The biotech company has four product candidates in clinical development for the treatment of solid and hematologic malignancies based on this proprietary TriTAC platform.

Why is this Orphan Drug Designation an important milestone?

Well, according to Harpoon Therapeutics’ President and CEO Jerry McMahon, PhD, the move by the FDA in fact “represents a significant milestone in the development of HPN217 and recognizes its potential to address a significant unmet medical need in patients suffering from this position.”

Clinical Research

By April 2020 Harpoon shared with the market they dosed the first patient with HPN217 (BMCA TriTAC) in a Phase 1/2 clinical trial (NCT04184050) focused on relapsed/refractory multiple myeloma (RRMM). HPN217 is covered by a global development and option agreement with AbbVie, Inc. Dose escalation for HPN217 in the Phase 1/2 clinical trial is progressing rapidly. Thus far the therapy has been well tolerated and as of the firm’s press release earlier in January no DLTs had been observed as of the most recent December 1, 2020 data cutoff date. The company explains that it anticipates a presentation of interim data sometime in 2021 with initiation of a dose expansion cohort in the second half of 2021.

Estimated primary completion date for this study is January 2, 2024.

Research Sites

According to the company’s ClinicalTrials.gov disclosure the study includes several sites in the U.S. and one in Spain. In the U.S. they include Banner MD Anderson Cancer Center in Arizona; Colorado Blood Cancer Institute, CO; the University of Kansas Cancer Center, KS; Roswell Park Comprehensive Cancer Center, Buffalo, NY; University of Rochester James P Wilmot Cancer Institute, Rochester, NY; OHSU, Portland, OR; Swedish Medical Center, Seattle, WA and University of Washington, Seattle Cancer Center Alliance, Seattle, WA. In Spain the study is conducted at Clinica Universidad de Navarra, Pamplona, Navara, Spain and Hospital Universitario Fundacion Jimenez Diaz (UAM-FJD), Madrid, Spain.

Harpoon Therapeutics

Harpoon Therapeutics is a clinical-stage immunotherapy venture 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 TriTAC platform mentioned previously, the company is developing a pipeline of novel TriTACs initially focused on the treatment of solid and hematologic malignancies. For example HPN424 targets PSMA and is in a Phase 1/2a trial for metastatic castration-resistant prostate cancer. While HPN424 targets PSMA and is in a Phase 1/2a trial for metastatic castration resistant prostate cancer. HPN536 targets mesothelin and is in a Phase 1/2a trial for cancers expressing mesothelin, initially focused on ovarian and pancreatic cancers. HPN217 targets BCMA and is in a Phase 1/2 trial for relapsed, refractory multiple myeloma. HPN328 targets DLL3 and is in a Phase 1/2 trial for small cell lung cancer and other DLL3-associated tumors. 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.

Founded in 2015 the company is publicly traded (HARP) with a current price of 19.28 and a 52 week high/low of 10.27 to 25.24. Like many biotech the firm loses money while it develops its products and lives off a combination of venture capital and then public investors.

The firm’s top five investors include MPM Asset Management LLC (17.83%); MPM Oncology Impact Management LP (15.36%); New Leaf Venture Partners LLC (11.51%); Orbimed Advisors LLC (7.23%) and Avidity Partners Management LP (4.62%) totaling 56.5% of total outstanding shares.

Lead Research/Investigators

·         Sumit Madan, MD, Banner MD Anderson

·         Henning Schade, MD, Colorado Blood Cancer Institute

·         Jens Hillengass, MD, PhD, Roswell Park Comprehensive Cancer Center

·         Brea Lipe, MD, University of Rochester

·         Eva Medvedova, MD, OHSU

·         William Bensigner, MD, Swedish Medical Center

·         Andrew Cowan, MD, University of Washington, Seattle Cancer Care Alliance

·         Daniel Morillo, MD, Hospital Universitario Fundacion Jimenez Diaz