** Canadian drugmaker’s U.S.-listed shares plunge 20 pct to $1.21, second biggest decliner across U.S. exchanges in premarket
** Co raises substantial doubt about its ability to continue as a going concern due to liquidity issues
** As of March 31, co had cash and cash equivalents of about $43.9 million
** Posts a wider-than-expected Q1 loss; withdraws previous guidance
** Says to immediately wind down its U.S. commercial business and ultimately shut down U.S. operations; to focus on Canadian business
** U.S.-listed shares set to more that erase YTD gains of 7 pct; Canadian-listed shares rose ~8 pct YTD (Reporting by Shreyashi Sanyal in Bengaluru)
