Abbott Laboratories is hoping to expand the indications for its anti-inflammatory blockbuster Humira and has filed for paediatric approvals in the USA and Europe.

The company has simultaneously submitted a supplemental Biologics License Application with the US Food and Drug Administration and a Type II Variation to the European Medicines Agency seeking approval to market Humira (adalimumab) as a treatment for juvenile rheumatoid arthritis (or juvenile idiopathic arthritis as it is referred to in Europe), marking the first paediatric indication sought for Humira.

It is the most common form of arthritis in children and normally begins before the age of 16, notes Abbott. Typical symptoms include persistent joint pain and stiffness that are usually worse in the morning or after a nap and the pain may limit movement of the affected joint, although many children will not complain of the pain. Walking with a limp is an early sign of JRA due to an affected knee and “if left untreated, JRA may slow a child's growth and cause disability into adulthood," said Daniel Lovell of the Cincinnati Children's Hospital Medical Center.

The filings are based on the results of a Phase III, 48-week study that included 171 children (4 to 17 years old) with polyarticular JRA, a form of arthritis affecting five or more joints. In the first part of the study, one group of patients taking methotrexate (MTX) and another group not on the latter, received Humira subcutaneously every other week for 16 weeks. 133 children who showed a positive clinical response entered the second part of the study and they had significantly fewer disease flares than children on placebo, both without MTX (43% versus 71%) and with that drug (37% versus 65%).

Additionally, twice as many children on Humira achieved ACR Ped 70 (that is a 70% improvement in JRA symptoms deemed important by the American College of Rheumatology) compared to those on placebo (56% versus 28%, respectively) at week 48. Further data will be submitted from an ongoing open label extension study evaluating the long-term efficacy and safety of Humira.

Humira is currently being studied in paediatric Crohn's disease and Abbott plans to initiate trials for paediatric and adolescent psoriasis later this year. All these moves are likely to push sales of the drug, which reached $571 million in the first quarter, even further.

Stock upgrade from Lehman Bros

Meantime, Tony Butler at Lehman Brothers has upgraded Abbott from ‘equal weight’ to ‘overweight’, while raising his estimates from $60 to $65. In a research note, the analyst says the firm’s pharmaceutical business could be doing better and although he believes Humira sales for the first quarter were disappointing, recent progress on label expansions may result in the drug beating expectations in the second half of this year and 2008.

Mr Butler believes that the current valuation of Abbott’s stock does not fully reflect its growth prospects, and earnings per share estimates for 2007 and 2008 have been raised from $2.85 to $2.86 and from $2.26 to $3.32, respectively.