A new U.S.-China drug discovery deal focused on developing bispecific therapies for cancer could bring Woburn, Mass.-based Abpro Therapeutics Inc. as much $4 billion, including $60 million in near-term R&D funding from its Chinese partner, NJCTTQ, a subsidiary of Nanjing Chia Tai Tianqing Pharmaceutical Group Co. Ltd. Outside of China and Thailand, Abpro will retain all commercial rights for any approved molecules, while NJCTTQ will retain rights in China.