Merck & Co. is pruning its pipeline of antibody-drug conjugates (ADCs). Days after the Big Pharma paid $4 billion for three Daiichi Sankyo assets, Kelun-Biotech has revealed the Big Pharma has decided (PDF) to pass over two of its preclinical ADCs.
China’s Kelun has played a starring role in Merck’s drive into ADCs over the past 18 months. The companies penned three pacts in short order, giving Merck rights to a trio of clinical candidates against targets such as TROP2 and CLDN18.2 as well as up to six preclinical prospects. Now, having quickly built a pipeline of nine partnered programs, Merck has told Kelun it is backing out of two of the preclinical projects.
Merck is terminating its license to one preclinical ADC and turning down an option to pick up a second preclinical program. The Big Pharma told Kelun it remains committed to the broader ADC collaboration and plans to “rapidly advance the clinical development program” for the TROP2-directed MK-2870.
The core of the collaboration remains in place, with Merck continuing to work with Kelun to advance the lead partnered program MK-2870, the CLDN18.2-directed MK-1200 and a third phase 1 asset. The three candidates are part of a Merck pipeline that, with the addition of the Daiichi assets, hits many of the top targets for ADCs.
Merck contacted Kelun the day after disclosing the Daiichi deal. The timing of the news, and the fact that ADC developers are clustered around a small set of targets, suggests Merck may have severed its ties to the two preclinical Kelun programs because they are directed at the same receptors as the clinical-phase ADCs it is picking up from Daiichi. The Daiichi deal covers ADCs aimed at HER3, B7-H3 and CDH6.
Whatever the reason for the action, Merck’s decision to walk away puts two ADCs back in play. Kelun will continue to work on the candidates and explore opportunities to collaborate with other partners. Several Western drugmakers have identified China as a productive source of ADCs, with AstraZeneca, BioNTech and GSK among the companies to pick up programs in the country.