HPN217 Receives FDA Fast Track Designation for Relapsed/Refractory Multiple Myeloma

The FDA granted fast track designation to the BCMA-targeting Tri-specific T-cell Activating Construct, HPN217, for patients with relapsed or refractory multiple myeloma who received at least 4 lines of prior therapy.

The FDA granted fast track designation to HPN217 for the treatment of patients with relapsed or refractory multiple myeloma who received at least 4 previous lines of therapy, according to a press release from the developer, Harpoon Therapeutics.1

This fast track designation is intended to facilitate the development and expedite the review of drugs to treat serious conditions and fulfill an existing medical unmet need. HPN217 is currently being assessed as part of the ongoing, multicenter phase 1/2 clinical trial (NCT04184050) in a population of patients with relapsed or refractory multiple myeloma.

“We are pleased that HPN217 has received FDA Fast Track designation because it highlights the serious unmet medical need for patients with relapsed/refractory multiple myeloma who received multiple lines of therapy,” Julie Eastland, president and chief executive officer at Harpoon Therapeutics, said in a press release. “We are focused on selecting an initial dose to study in the expansion phase of the ongoing phase 1/2 clinical trial in the first half of this year as we progress HPN217 forward as an innovative new treatment option for these patients.”

Interim results for the phase 1/2 trial were presented at the 2021 American Society of Hematology Annual Meeting and Exposition, confirming the safety of administering HPN217 at a weekly dose of 2150 µg.2 Dose escalation for the BCMA-targeting Tri-specific T-cell Activating Construct (TriTAC), HPN217, is ongoing.

The primary end points for the interim analysis were safety, tolerability, and determining the maximum tolerated dose and/or the recommended phase 2 dose. Secondary end points include investigated pharmacokinetics, pharmacodynamics, immunogenicity, and preliminary anti-myeloma activity.

As of July 5, 2021, a total of 22 patients had received treatment with HPN217 in 8 cohorts with doses ranging from 5 to 2150 µg. The median number of prior systemic therapies was 8 (range, 4-16), with 5 patients receiving BCMA-targeted belantamab mafodotin-blmf (Blenrep) or orvacabtagene autoleucel.

Common treatment-emergent adverse effects included anemia, neutropenia, and thrombocytopenia. No evidence of cytokine release syndrome (CRS) was observed among patients receiving a weekly dose between 5 to 270 µg. Grade 1 and 2 CRS was observed in 4 patients who received a weekly dose of 810 µg or greater.

Moreover, transient elevated liver transaminases (grade 4 AST and grade 3 ALT) were observed in a patient treated at a weekly dose of 810 µg. Another patient treated with a weekly dose of 270 µg experienced a grade 1 AST increase. All CRS events and liver enzyme increases were resolved, and patients were successfully re-treated with escalating doses.


  1. Harpoon Therapeutics receives FDA fast track designation for HPN217. News release. Harpoon Therapeutics. March 2, 2022. Accessed March 8, 2022. https://tinyurl.com/3dhfcyuf
  2. Madan S, Abdallah A-O, Cowan AJ, et al. An interim report on a phase 1/2 study of HPN217, a half-life extended Tri-specific T Cell Activating Construct (TriTAC®) targeting B cell maturation antigen for the treatment of relapsed/refractory multiple myeloma. Blood. 2021;138(suppl 1):1654. doi:10.1182/blood-2021-148176