Two rivals aiming to muscle in on Johnson & Johnson and Schering-Plough’s Remicade in the market for Crohn’s disease treatments reported strong Phase III data yesterday at the Digestive Diseases Week conference in Los Angeles, USA.

Remicade (infliximab) is currently the only biologic approved to treat Crohn’s, a chronic inflammatory condition affecting the bowel. But UCB’s Cimzia (certolizumab pegol) and Abbott Laboratories’ Humira (adalimumab) are both aiming to grab a slice of the market. All three work by inhibiting the inflammatory mediator tumour necrosis factor (TNF).

UCB reported results from the PRECiSE1 study showing that its long-acting, once-monthly drug was more effective than placebo at maintaining clinical response in moderate to severe Crohn’s patients – defined as a 100-point improvement on the Crohn’s disease activity index scale – over six months.

The results were particularly significant, according to UCB, because unlike other trials of biologics in Crohn’s disease the study did not include a screening phase, in which non-responders were weeded out from the trial population.

Olav Hellebo, president of inflammation operations at UCB, said: “when looking at different anti-TNF studies, we found that the overall remission rate at 26 weeks is a key indicator of treatment success.”

He noted that the six month remission rates were 30% for PRECiSE 1, which tallies with a 31% rate seen in an earlier trial (PRECiSE 2). Moreover, just under 30% of patients on Cimzia went into full remission after six months, compared to 18% of the placebo group.

Meanwhile, Abbott reported new data from the CHARM study of Humira, given either weekly or every other week, showing that it was able to maintain remission in patients with moderate to severe Crohn’s disease out to one year.

On the weekly dose, 46% were in remission at six months, dipping to 41% at the end of the year-long study. With every other week dosing the proportions were 40% and 36%, respectively.

In this 854-patient study, an open-label induction period and initial randomisation out to four weeks was used to identify non-responders and early withdrawals. 499 patients were included in the efficacy analysis.

Remicade was first approved in 1998 for the treatment of adults with Crohn's disease, and has just had its indications extended to include children with the disease. The drug made up the lion’s share of the $1 billion Crohn’s disease market in 2004, according to a report published last year by Decision Resources, as other drugs used to treat the condition – corticosteroids, azathioprine, 6-mercaptopurine and the salicylates, are generic and cheaply available.

The report, published last October, suggested that Cimzia and Humira will quickly win market share from Remicade, as they offer advantages in terms of safety, efficacy and convenience. UCB filed for approval of Cimzia in both Europe and the USA earlier this year, while Abbott plans to submit an application for Humira before the end of 2006.

Other drugs which could compete with Remicade and potentially Humira and Cimzia in the Crohn’s disease sector in the coming years include Abbott’s IL-12 inhibitor ABT-874 (Phase II) and Elan/Biogen Idec’s suspended but set to return to market multiple sclerosis drug Tysabri (natalizumab; Phase III in Crohn’s disease). There is also an immune stimulator in clinical development for Crohn’s disease – Berlex’ sargramostim - which addresses the hypothesis that a defect of the intestinal immune system may be in part to blame for Crohn’s disease.