Targeted treatment can be wonderful, producing dramatically effective patient improvement with little or no adverse effects.
One apparent, new example of a highly targeted, remarkably effective treatment reported last month at the annual European Congress of Rheumatology (EULAR) came from a study of 112 children and adolescents with systemic juvenile idiopathic arthritis (JIA) randomized to treatment with the interleukin (IL)-6 inhibitor tocilizumab or placebo.
After 12 weeks of treatment, the 75 patients randomized to a tocilizumab infusion every 2 weeks had a 85% ACR50 response rate, a 71% ACR70 response rate, and even a 37% ACR90 response rate, compared with respective response rates of 11%, 8%, and 5% among 37 patients randomized to placebo treatment in a multicenter study. These responses occurred with just three of the 75 patients on tocilizumab having a serious adverse event.
An ACR70 response rate of 71% is spectacular, especially compared with a matched placebo rate of 8% and after just 12 weeks of treatment. An ACR70 response means that the patient had a 70% reduction in swollen and tender joints as well as in at least three of five other response categories, and is at the upper end of response levels usually measured in arthritis trials. (Some studies only look at ACR20 responses, patients having a 20% improvement in their joint counts and other symptoms.)
By comparison, in one of the phase III trials that led to tocilizumab’s approval as a treatment for rheumatoid arthritis earlier this year, the TOWARD trial with more than 1,200 rheumatoid arthritis patients, the ACR70 response rate after 24 weeks of treatment was 21% in the tocilizumab recipients and 3% in the placebo group.
Why did tocilizumab do so well for systemic JIA? “A vast body of evidence suggests that IL-6 drives” the disease, said Dr. Fabrizio De Benedetti, the Italian rheumatologist who led the new study.
Apply the right drug to the right patients, and the results can be incredibly successful. The only problem is that systemic JIA is not very common. It constitutes about 10%-15% of all JIA, itself a relatively uncommon disorder. Dr. De Benedetti estimated that perhaps about 3,000 patients with systemic JIA exist throughout the entire European Union, a population of about 500 million.
—Mitchel Zoler (on Twitter @mitchelzoler)