DUBLIN – A 2.5 percent share price drop – or a €2.5 billion (US$3 billion) loss of value – is not the best way to begin a pipeline update. But amid continued uncertainty about the leadership situation at Sanofi Group, that was the hand its chairman and interim CEO, Serge Weinberg, had to play as the company set out its stall Thursday on a late-stage pipeline that it contended will deliver cumulative revenues of €30 billion over the first five years of sales.