GlaxoSmithKline has extended its offer to acquire all of the outstanding shares of Human Genome Sciences for 1,300 cents per share until 17:00 on July 20th. GSK's tender offer will expire after 16 July, the deadline set by HGS for submission of definitive acquisition proposals, after which GSK will consider all available options regarding its offer, but said it can make no assurance that the tender offer will be further extended. The company reitered that it "remains willing to meet and review its offer with HGS at any time".The offer represents a premium of 81% to HGS's closing share price of $7.17 on April 18th , the last trading day before HGS publicly disclosed GSK's private offer."Given its near 20-year relationship with HGS and ownership of 50% of Benlysta as well as the vast majority of the economics associated with albiglutide and darapladib, GSK continues to believe it is uniquely positioned to deliver on the opportunity of the proposed combination," GSK commented. GSK's share price fell 0.69% to 1,436p by 13:10.NR