Merck & Co. (MSD) has concluded the acquisition of Harpoon Therapeutics to broaden its oncology pipeline.

In January 2024, MSD entered a definitive agreement to acquire all the outstanding shares of the US-based company for $680m.

Harpoon will function as a wholly owned subsidiary of MSD and its common stock will not be publicly traded or listed on the Nasdaq exchange.

MSD has gained access to Harpoon's portfolio of T-cell engagers, including MK-6070 (formerly HPN328).

A leading candidate of the company, MK-6070 is a T-cell engager that targets delta-like ligand 3 (DLL3).

DLL3 is an inhibitory canonical Notch ligand prevalent in small-cell lung cancer (SCLC) and neuroendocrine tumours.

A Phase I/II clinical trial is assessing the tolerability, safety and pharmacokinetics of MK-6070 as a monotherapy for patients with advanced DLL3-associated cancers.

The study is also assessing the drug with atezolizumab for SCLC.

MK-6070 obtained orphan drug designation from the US Food and Drug Administration (FDA) to treat SCLC in March 2022.

The acquisition also includes pipeline assets such as HPN217, a T-cell engager targeting B-cell maturation antigen.

It is under development to treat relapsed/refractory multiple myeloma treatment in a Phase I clinical trial.

Preclinical stage candidates such as HPN601 are also being developed to treat epithelial cell adhesion molecule-expressing tumours.

Merck Research Laboratories president Dr Dean Li stated: “We continue to augment and diversify our oncology pipeline with innovative approaches to help people with cancer worldwide.

“We are pleased to welcome our Harpoon colleagues to Merck and look forward to working together to advance a novel portfolio of T-cell engagers, including MK-6070.”

Last month, the Committee for Medicinal Products for Human Use of the European Medicines Agency provided a positive opinion recommending approval for MSD’s Keytruda in combination with chemotherapy for non-small cell lung cancer.