GlaxoSmithKline (NYSE: GSK) is not giving up in its hostile takeover offer for Human Genome Sciences Inc. (Nasdaq: HGSI), which reiterated last week that it rejects GSK’s $2.6 billion bid.

GSK “confirmed that it has received a renewed invitation from Human Genome Sciences’ \to participate in its strategic alternatives review process which started in April,” the drug giant said in a statement Friday.

“GSK also notes the newly announced date of 16 July 2012 for submission of definitive acquisition proposals.”

HGSI had issued a statement about that invitation earlier.

“GSK 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,” the company added. “GSK knows HGS well based on a 20-year relationship and is uniquely positioned to deliver on the opportunity of the combination. GSK has therefore today sent a letter to HGS declining again to participate in this process.”

Few shares have been tendered to GSK, which is offering $13 for each.

“The company continues to believe that this offer reflects full and fair value and is in the interest of shareholders of both companies,” GSK said in the statement. “The transaction is well aligned to GSK’s long-term strategy of delivering sustainable growth, simplifying GSK’s business model, enhancing R&D returns and deploying capital with discipline. For HGS shareholders, it provides immediate liquidity at a substantial premium while eliminating further exposure to the significant execution risk inherent in HGS achieving its future growth objectives. GSK’s offer reflects the value of Benlysta, darapladib, albiglutide, HGS’s operating and financial assets, and expected cost synergies of at least US$200 million.”

GSK, which maintains its U.S. headquarters in RTP, recently extended its tender offer to June 29.

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