Patients with ankylosing spondylitis gain a significant therapeutic benefit from treatment with Abbott Laboratories’ Humira for at least a year, according to new data from the ATLAS study.

And the results raise expectations that using TNF blockers such as Humira in ankylosing spondylitis patients could, with early diagnosis, achieve long-term remission in 40%-50% of patients, whilst even in late-stage patients a remission rate of around 25% can be hoped for, according to Joachim Sieper of Campus Benjamin Franklin at the University of Berlin.

Ankylosing spondylitis, an arthritis-like syndrome predominantly affecting the spine but also sometimes involving other organs in the body, is surprisingly common, with a prevalence of around 0.5% of the population, rising to around 1% in some countries. That puts it on a par with rheumatoid arthritis, with a prevalence of 0.5% to 0.8%, although ankylosing spondylitis is not as well recognised and, as a result, chronically under-diagnosed.

The first results of the ATLAS study, which compared six months’ treatment with Humira with placebo in patients with active ankylosing spondylitis, formed the basis of EU approval and showed that the drug could reduce symptoms by 20% (ASAS20 response) in around 60% of patients, while around half of the patients on Humira saw a 40% improvement or better (ASAS40).

Those on placebo then crossed over to Humira treatment for the remainder of the two-year study, and results at 12 months were presented at the European league against Rheumatism (EULAR) meeting in Amsterdam last Friday. This showed that after 12 months, the proportion of patients meeting the ASAS20 criteria rose to 74%, while ASAS40 responses were seen in around 55%.

The new analysis also revealed significant improvements in pain and fatigue with Humira compared to placebo at six months.

Humira was cleared for ankylosing spondylitis in Europe on June 7, joining Schering-Plough’s Remicade (infliximab) and Wyeth’s Enbrel (etanercept), two other TNF blockers that are also cleared for the disease as well as various other indications including rheumatoid arthritis.

Sieper told PharmaTimes that while the TNF blockers are cleared for use as a second-line treatment after conventional non-steroidal anti-inflammatory drugs, two clinical trials are now ongoing to test Humira as a first-line treatment in ankylosing spondylitis.

But the main problem is that the disease is under-diagnosed, mainly because it is hard to differentiate from other causes of back pain. There is a need for a diagnostic test, he said, with genetic testing for the HLA-B27 gene – closely linked to the development of the disease - one option that is under consideration. This is relatively inexpensive at around 40 euros a go, and while unable to give a definitive diagnosis could certainly aid in the identification of ankylosing spondylitis patients early on.

Meanwhile, Abbott will be hoping that the dosing regimen for Humira – a subcutaneous injection every two weeks – will help its drug win market share in the ankylosing spondylitis sector versus its more established rivals. Remicade is given by infusion at weeks 0,2 and 6 weeks and every 6-8 weeks thereafter, while Enbrel is given once or twice a week by subcutaneous injection.

- Abbott also said yesterday that the FDA had approved Humira Pen, a new patient-friendly device for administering the rheumatoid arthritis and psoriatic arthritis drug. The Humira Pen will be available in the USA beginning in August.