Merck & Daiichi Sankyo strengthen partnership with new DLL3 cancer drug deal

Merck & Co. and Daiichi Sankyo are enhancing their collaboration in oncology through a new agreement to jointly develop and commercialize MK-6070, a DLL3-targeting T-cell engager. The announcement on Tuesday extends their existing partnership, which initially involved a $4 billion upfront payment by Merck last October to support the development of three of Daiichi Sankyo's antibody-drug conjugates (ADCs).

As part of the new deal, Daiichi Sankyo will provide an upfront payment of $170 million to Merck. Both companies will share the costs related to research and development, commercialization, and profits on a global scale, with the exception of Japan. In Japan, Merck holds exclusive rights and Daiichi Sankyo will receive royalties based on sales.

MK-6070, which Merck acquired earlier this year through its $680-million acquisition of Harpoon Therapeutics, is currently undergoing a Phase I/II clinical trial. This trial involves patients with advanced cancers that are associated with DLL3, a Notch inhibitory ligand prevalent in small-cell lung cancer (SCLC) and neuroendocrine tumors, but with minimal to no expression in healthy cells. The study, expected to give results in 2025, is evaluating MK-6070 both as a standalone treatment and in combination with Roche's Tecentriq (atezolizumab).

In addition to these trials, Merck and Daiichi Sankyo plan to explore the use of MK-6070 in combination with ifinatamab deruxtecan (I-DXd), one of the ADCs included in their initial agreement, for specific SCLC patients. The companies are also considering other combination treatments. Ken Takeshita, global head of R&D at Daiichi Sankyo, stated that the inclusion of MK-6070 could create synergies with their established ADC collaboration, particularly with ifinatamab deruxtecan.

The original agreement from last October, which has the potential to reach up to $22 billion considering various payments and future sales milestones, included two other ADC candidates: patritumab deruxtecan and raludotatug deruxtecan.

This new agreement follows the recent rapid FDA approval of Amgen's Imdelltra (tarlatamab), a bispecific T-cell engager (BiTE) targeting DLL3 and CD3. Imdelltra is indicated for the treatment of extensive-stage SCLC in patients whose disease has progressed after platinum-based chemotherapy. The approval of Imdelltra sets a precedent for other DLL3-targeting therapies as a viable treatment option for SCLC, though it also underscores the challenges that come with these treatments. The drug’s label includes a boxed warning about potentially life-threatening cytokine release syndrome and neurologic toxicity.