For three whirlwind days in June, U.S. scientist Zhi Hong went shopping at the Boston Bio Conference to find drugs to fill the pipeline of his 2-week-old drug company.

Crammed in tight, four-person booths that executives use for private conversations, the former GlaxoSmithKline PLC executive pitched dozens of U.S. biotech companies to partner with his startup, Brii Biosciences.

Months earlier, Hong had raised $260 million — much of it from Chinese and Asian investors — with a strategy to bring U.S. biotechnology drugs to China, the world's second-largest prescription drug market and home to a rapidly growing biotech sector.