Human Genome Sciences has set a deadline of July 16 for offers to acquire the company but its efforts to get hostile bidder GlaxoSmithKline to join the process seem to have fallen on deaf ears.

The US biotech says that in connection with its ongoing strategic alternative review, potential buyers have a month or so "for the submission of definitive proposals" to purchase all its outstanding common shares. The firm announced the review in April when GSK first made its $13.00 per share offer, which valued HGS at $2.60 billion.

GSK's offer has been repeatedly rejected and there has been much to-ing and fro-ing between the two firms. HGS, which adopted a shareholder rights plans, or 'poison pill' to thwart GSK after the drugs giant declined to enter the review process. Last week, the latter extended its tender offer to June 29 from June 7 without changing the terms.

HGS has now sent a letter once again inviting GSK to participate in the ongoing process and provide by July 16 its "final bid terms". However the company is clearly not interested in that approach.

Indeed, GSK responded promptly, saying it "continues to believe that participation in the process is unnecessary given the company's offer is not conditioned on due diligence or financing and can be completed expeditiously". It will continue to progress with its offer direct to HGS stockholders, although by the last deadline, less than 1% of HGS' outstanding shares had tendered.

It has also been reported previously that GSK will seek the backing from HGS shareholders to replace the entire board with 12 independent directors. No other companies have made their interest public in HGS, which developed the lupus drug Benlysta (belimumab) with GSK. The firms are also partners on the late-stage cardiovascular treatment darapladib and albiglutide, currently in Phase III for the treatment of type 2 diabetes.

GSK gets FDA thumbs-up for MenHibrix

Meantime, GSK also announced that the US Food and Drug Administration has finally approved MenHibrix, which combines its meningococcal and Hib vaccine. It is indicated to prevent invasive disease caused by Neisseria meningitidis serogroups C and Y and Haemophilus influenzae type b.

The vaccine had previously been turned down twice by the agency. Leonard Friedland at GSK Vaccines, said that MenHibrix gives doctors the option of combining Hib with meningococcal C and Y immunisation without increasing the number of shots for infants and toddlers".