Cleary Gottlieb Steen & Hamilton and Wachtell Lipton Rosen & Katz are among a host of US firms to take lead roles on GlaxoSmithKline's (GSK) $2.8bn (£1.8bn) acquisition of Human Genome Sciences (HGS), ending a three-month hostile pursuit of the biotech company after bettering its offer.

Cleary and Wachtell shared the mandate for GSK, with New York-based corporate heavyweights Victor Lewkow and Adam Emmerich taking the lead for the respective firms.

Britain's biggest drugmaker will pay around $14 (£9) per share, up from a $13 (£8) offer rejected by HGS – an early pioneer of gene-based drug discovery – earlier this year.

HGS instructed Skadden Arps Slate Meagher & Flom and DLA Piper as joint counsel on the deal. Skadden fielded a Washington DC-based team for HGS, which is headquartered in nearby Rockville, Maryland. The US firm's team was led by corporate partners Marc Gerber and Michael Rogan.

HGS decided to go public with GSK's initial offer earlier this year – thereby putting itself up for sale – anticipating interest from other pharmaceutical giants may drive up the price.

GSK has a host of regular advisers on European deals, with magic circle firm Slaughter and May earlier this year collaborating with German and Italian best friends Hengeler Mueller and Bonelli Erede Pappalardo to advise the pharma giant on its €470m (£393m) divestment of a portfolio of European over-the-counter (OTC) healthcare products to Omega Pharma.