** Hong Kong-listed shares of WuXi AppTec 2359.HK climb 3.8% to HK$121.2, on track for the biggest one-day pct gain since May 29

** Stock on course to snap two sessions of losses

** Shanghai-listed stock 603259.SS gains 4% to 97.26 yuan, set for the biggest one-day pct rise since April 28

** Chinese new drug developer and manufacturer plans to buy back up to 1 bln yuan ($147.64 mln) worth of company A-shares

** YTD, Hong Kong shares up 21.6%, Shanghai-listed shares up 7.2%, while Hang Seng Biotech Index .HSBIO down 16.5%

($1 = 6.7733 Chinese yuan renminbi)