** Shares of ImmuneOnco Biopharmaceuticals Shanghai 1541.HK drop 13.5% to HK$14.41, on course for their biggest one-day pct decline since April 7

** The China-based tumor immunotherapy developer plans sale of 24.2 mln new shares to third party investors in share placement, raising HK$350.9 mln ($45.10 mln) for R&D of therapy for treatment of solid tumors in China, among others

** The new shares will be issued at HK$14.50 apiece, or nearly 13% discount to Wednesday close of HK$16.66 each

** YTD, stock up 180.8%, Hang Seng Biotech Index .HSBIO up 104.6%

($1 = 7.7806 Hong Kong dollars)

(Reporting by Donny Kwok)

((donny.kwok@thomsonreuters.com))