** Shares of Mayne Pharma MYX.AX climb as much as 26.1% to A$6.040, posting their biggest pct gain since February 21
** Australia’s Takeovers Panel declares “unacceptable circumstances” in Cosette Pharmaceuticals’ A$7.40 per share bid
** Panel says Cosette’s plan to close or sell MYX's Salisbury manufacturing site was inconsistent with earlier disclosures
** Last month, a court ruled Cosette’s termination notice was invalid, keeping the deal alive
** Stock last up 17.5%, taking YTD gains to 13.3%
(Reporting by Kumar Tanishk in Bengaluru)
((Tanishk.Kumar@thomsonreuters.com; X: @thatstanishk http://www.x.com/thatstanishk;))