Startups, BioPharma

Harpoon Therapeutics files for $86.25M IPO

The company's Form S-1 filing comes less than two months after it completed a $70 million Series C financing.

T-cells attacking cancer cell illustration of microscopic photosT-cells attacking cancer cell illustration of microscopic photos

Less than two months after closing its latest round of venture capital funding, a company developing monoclonal antibodies that engage the body’s own T cells has filed to go public.

South San Francisco, California-based Harpoon Therapeutics said Thursday that it had filed an S-1 form with the Securities and Exchange Commission for an initial public offering. The company would trade on the Nasdaq under the ticker symbol “HARP.”

According to the filing, the company is seeking to raise $86.25 million in the IPO. Citigroup and Leerink Partners are acting as book runners, while Canaccord Genuity and Wedbush PacGrow are co-managers. Harpoon said on Nov. 13 that it had raised $70 million in a Series C funding round, led by OrbiMed.

The company’s drug-development platform is dubbed TriTAC, for Tri-specific T-cell Activating Construct. Like other T-cell engagers, the monoclonal antibodies work by redirecting T cells to attack the tumor cells they have targeted. The company is currently running a Phase I study of its lead product candidate, HPN424, for metastatic, castration-resistant prostate cancer, which opened at the end of July and is planned to enroll 40 patients. Next year, the company plans to bring two additional product candidates into the clinic. One is HPN536, which targets mesothelin in cancers that express that antigen. The other is HPN217, which targets the antigen BCMA in the blood cancer multiple myeloma.

The only T-cell engager currently on the market is Amgen’s Blincyto (blinatumomab), which targets the CD19 antigen in acute lymphoblastic leukemia and was developed using the company’s BiTE platform, whose name stands for Bi-specific T-cell Engager. Another BiTE antibody is AMG 420, which – like HPN217 – targets BCMA in multiple myeloma. Phase I data were presented at the American Society of Hematology meeting last month.

Another company developing T-cell engagers is Rockville, Maryland-based MacroGenics, which calls its bispecific antibody platform DART. Last month, the Food and Drug Administration placed a partial clinical hold on two studies of MGD009, a bispecific antibody that targets B7-H3, due to concerns about liver toxicity. The partial hold means the trial cannot enroll new study participants, but current participants may continue receiving the drug.

Photo: royaltystockphoto, Getty Images

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