PALO ALTO, California—Adalimumab (Humira®, Abbott Laboratories) is safe and effective in patients with active psoriatic arthritis (PsA) who showed an inadequate response to disease- modifying antirheumatic drugs (DMARDs), according to a second phase III trial for this TNF-inhibitor. The findings appear in the May issue of the Journal of Rheumatology.¹

"Despite the relatively small size of this study, adalimumab was found to have been well tolerated, to have significantly reduced the signs and symptoms of arthritis, and to have significantly improved psoriasis and disability," conclude researchers led by Mark C. Genovese, MD, associate professor of medicine at Stanford University Medical Center, in California.

In the new study, 51 PsA patients were treated for 12 weeks with subcutaneous injections of adalimumab 40 mg every other week, and 49 PsA patients received placebo. This was followed by a period of open-label treatment with adalimumab of 40 mg every other week.

At week 12, 39% of PsA patients receiving adalimumab achieved an ACR20 response, compared with 16% of participants who received placebo (P = .012). In addition, 51% of patients taking adalimumab achieved a Psoriatic Arthritis Response Criteria (PsARC) response, compared with 24% of patients on placebo (P = .007). Measures of skin lesions and disability were also improved with adalimumab at week 12, the study found.

After week 12, placebo patients who opted into the open-label adalimumab trial achieved rapid improvements, and patients initially in the adalimumab arm continued to improve. At week 24, 65% of patients initially randomized to receive adalimumab achieved an ACR20 response, as did 57% of patients who switched over from placebo.

Adalimumab safe and well tolerated

Serious adverse events had similar frequencies during treatment with placebo (4.1%), blinded adalimumab (2%), and open-label adalimumab (3.1%).  Infections, most of which were upper respiratory, occurred in adalimumab-treated patients about half as frequently as they did in placebo patients, but these differences did not reach statistical significance. There were no cases of tuberculosis, granulomatous infection, demyelination, drug-induced lupus, or congestive heart failure during 24 weeks of observation.

No patients treated with adalimumab developed cancer, but three patients in the placebo group did develop malignancies. One malignancy was diagnosed 3 days after the patient switched over to adalimumab, and another was retrospectively apparent before the patient began treatment with the TNF-blocker, leading the researchers to conclude that the malignancies were unrelated to TNF-inhibition.

"All [studies] point to the value of anti-TNF therapy in treating joint, skin, function, and QOL manifestations of PsA," study coauthor Philip J. Mease, MD, told CIAOMed. "Usually governmental agencies or insurance companies force us to start with methotrexate, but in a significant portion of patients, this will prove to be  inadequate, in which case we would add anti-TNF therapy. My sense is that there is a gradually increasing number of  patients being treated with anti-TNFs. The safety profile is good and is no different from the experience with these drugs in RA."

Reference

1. Genovese MC, Mease PJ, Thomson GTD, et al. Safety and efficacy of adalimumab in treatment of patients with psoriatic arthritis who had failed disease modifying antirheumatic drug therapy. J Rheumatol. 2007;34:1040-1050.