Cambridge Antibody Technology, the UK biotechnology company that could be snapped up by AstraZeneca, swung into its first-ever profit for the six months to March 31 on a sterling performance from its arthritis treatment Humira (adalimimab).

Profits for the first half amounted to £4.6 million on revenues of £27.7 million, comparing nicely to last year when it recorded a net loss of £16.5 million and income of just £9.8 million. The figures exclude the $225 million (£120 million) received in October last year from Abbott Laboratories in settlement of its royalty battle over Humira.

And a 2.68% return on sales of the arthritis agent certainly helped the UK biotech’s fortunes; Abbott recorded 2005 Humira sales of $1.4 billion and has forecasted this figure will jump to almost $2 billion this year. As a consequence, CAT says it received £12.9 million in Humira royalties during the period, and a further £10.9 million in annual payments from Abbott.

Shares in the UK biotechnology company edged only slightly higher on the news this morning, although that is perhaps expected as the stock is already trading at a 52-week high following the announcement of AstraZeneca’s £567-million offer for the remaining 81% of the firm it does not already own, valuing it at £702 million. The 1,302 pence offer is a 67% premium over CAT's closing price on Friday May 12, but the UK’s Office of Fair Trading has already announced that it is investigating the proposed takeover to see if it breaches competition rules.