Merck has recently agreed to acquire cancer drug developer Harpoon Therapeutics for about $680 million. The deal includes promising compounds undergoing Phase II trials for malignancies and access to the Tri-specific T cell Activating Construct (TriTAC) platform, positioning the US-based pharmaceutical giant for significant advancements in therapeutic innovation. The focus lies on contesting the evolving bispecific T-cell engager market, leveraging the TriTAC platform, says GlobalData, a leading data and analytics company.

Thomas Wales, MSc, Oncology Analyst at GlobalData, says: “Merck seeks to capitalize on the recent delta-like canonical Notch ligand 3 (DLL3) craze as well as B-cell maturation antigen (BCMA) targeting therapy with its acquisition of Harpoon Therapeutics.”

The deal includes the novel HPN-217 and HPN-328 compounds, which are currently undergoing Phase II clinical trials for various malignancies. The deal also gives Merck access to a host of therapies currently being evaluated in pre-clinical development, as well as the proprietary TriTAC platform.

Interim results from HPN-328’s Phase I/II clinical trial, showed promise as it produced a response in patients and was tolerable.

Wales continues: “GlobalData’s analysis of HPN-328’s likelihood of advancing to Phase III trials is relatively high. Traditionally, therapies within the SCLC indication would have a 25% phase transition success rate (PTSR) for advancing from Phase II to Phase III clinical trials, whereas HPN-328 is evaluated as having a PTSR of 44%.”

Following the success of Amgen’s tarlatamab Phase II clinical trial in previously treated SCLC, the FDA has assigned a priority review which will likely see the bispecific T-cell engager (BiTE) receive approval within the next year. The clinical results demonstrated good objective response rates in patients.

GlobalData analyst consensus forecast predicts that tarlatamab will rake in $781 million by 2029 and will establish itself as a market leader for SCLC treatment.

Wales concludes: “While the acquisition of Harpoon therapeutics will give the clinical and financial support needed to bring HPN-328 to Phase III clinical trials, it is unlikely that HPN-328 will surpass tarlatamab in the SCLC indication. Globaldata analyst consensus forecast predicts HPN-217 and -328 to reach global sales of $161 and $192 million, respectively, by 2029.

“As these global sales fall short of the $680 million acquisition, Merck will seek to manifest its own T-cell engager portfolio using TriTAC technology. If TriTAC therapies can demonstrate marked improvements in dosing regimens compared to BiTEs in a clinical setting, Merck could quickly de-throne Amgen as the lead developer in advanced SCLC therapeutics.”