By Millie Turner Investors have bailed out of GlaxoSmithKline (GSK) after the British pharmaceutical booked its second late-trial pipeline disappointment in just a few weeks. GSK’s stock price plunged more than four per cent to £13.48 per share by mid-afternoon. The firm announced this morning that its blood cancer drug Blenrep was no more effective than existing treatments. The drug had been pegged by GSK bosses as having the potential to help the firm achieve combined peak-year sales of more than £20bn. The disappointment follows that of rheumatoid arthritis drug Otilimab in late October, wh…