Chinese drugmaker Sichuan Kelun Pharmaceutical Co said on Monday that Merck & Co Inc was abandoning the joint development of two candidate cancer drugs which have yet to start clinical trials. Representatives for Merck did not immediately respond to a Reuters request for comment. The move comes days after Merck said it would pay Daiichi Sankyo $5.5 billion to jointly develop three of its candidate cancer drugs in a deal that could be worth up to $22 billion for the Japanese firm.