** Shares of Biotech firm Holista CollTech HCT.AX fall 20% to A$0.024, set for biggest one-day drop in four months
** Co says its appeal against damages totalling $2.1 mln for distribution agreement disputes with ProImmune was dismissed by the U.S. Court of Appeals
** Adds that it intends to "vigorously defend" any proceedings commenced in Australia, claiming the judgment was obtained by fraud due to ProImmune's false representations
** Stock slumped as much as 30% earlier in the day
** Over 295,000 shares change hands, 1.2x the 30-day avg
** Stock trims YTD gains to 84.6%
(Reporting by Kumar Tanishk in Bengaluru)
((Tanishk.Kumar@thomsonreuters.com; X: @thatstanishk http://www.x.com/thatstanishk;))