WASHINGTON (FRONTLINE MEDICAL NEWS) – Tofacitinib demonstrated efficacy comparable to adalimumab in patients with active psoriatic arthritis (PsA) and an inadequate response to conventional disease-modifying antirheumatic drugs in the phase III OPAL Broaden study.

“This is the first study to demonstrate efficacy of a JAK [Janus kinase] inhibitor in PsA,” said lead author Philip J. Mease, MD, of Swedish Medical Center, Seattle. “The primary endpoints were achieved with tofacitinib [Xeljanz] versus placebo. Onset of efficacy of tofacitinib on the ACR20 [the American College of Rheumatology 20% improvement criteria] was observed as early as week 2. Radiographic non-progression rates were low and similar to placebo. Improvement was seen in enthesitis and dactylitis as well as in joint and skin symptoms, and efficacy was maintained through month 12. Tofacitinib is a potential future option for the treatment of PsA.”

“The study was designed to estimate the treatment difference between tofacitinib and adalimumab, not to demonstrate inferiority or superiority [of one treatment over another],” Dr. Mease told listeners during a plenary session at the annual meeting of the American College of Rheumatology.

The study enrolled 422 patients with active PsA diagnosed within the last 6 months or longer, and all also had plaque psoriasis at screening. The primary endpoint was ACR20 response at 3 months.

Patients were randomized to receive tofacitinib 5 mg twice daily, tofacitinib 10 mg twice daily, adalimumab (Humira) 40 mg subcutaneously every 2 weeks, or placebo. At 3 months, placebo patients were re-randomized to tofacitinib 5 mg or 10 mg twice daily. The trial was completed by 372 patients (88.4%).

At baseline, groups had similar demographic and disease characteristics. Patients had a median age just under 50 years, tended to be overweight, and had disease duration that ranged from 5 to 7 years. The majority of patients had enthesitis and dactylitis, and all were on background disease-modifying antirheumatic drugs.

All of the active treatment arms achieved statistically significant rates versus placebo on the primary endpoint of ACR20 response at 3 months: 50% in the tofacitinib 5-mg group, 61% in the tofacitinib 10-mg group, and 52% in the adalimumab group, compared with 33% of placebo-treated patients. ACR20 responses increased out to 12 months in 68%, 70%, and 60%, respectively in the three active treatment arms. At 3 months, ACR50 responses in the three active treatment arms were 28%, 40%, and 33%, respectively, and for ACR70 were 17%, 14%, and 19%.

Health Assessment Questionnaire Disability Index (HAQ-DI) responses were statistically significant for all three active dosing arms, compared with placebo.

“Placebo patients re-randomized to tofacitinib also had good ACR responses at month 12,” Dr. Mease said.

The rate of radiographic non-progression at month 12 was similar in all treatment arms at about 95%, including former placebo patients who switched to tofacitinib.

Skin responses, according to Psoriasis Area and Severity Index (PASI) 75, were 43% for tofacitinib 5 mg twice daily, 44% for tofacitinib 10 mg twice daily, and 39% for adalimumab. At 12 months, the percentage of patients achieving PASI 75 increased for all three treatment arms.

The same pattern was observed for enthesitis and dactylitis.

Minimal disease activity was seen at 3 months in about 25% of all the active treatment arms, and the rates improved at month 12.

There were few discontinuations due to adverse events in any group. Adverse event rates were similar across all treatment arms at month 3, including the placebo arm. The rate of serious adverse events reported at month 12 was 5% for tofacitinib 5 mg twice daily, 2.9% for tofacitinib 10 mg twice daily, 7.8% for adalimumab, and 6% in placebo patients switched to either dose of tofacitinib at month 3.

Laboratory changes were similar to those reported with tofacitinib monotherapy in rheumatoid arthritis.

The study was sponsored by Pfizer. Dr. Mease’s financial disclosures included Pfizer as well as a long list of companies that make conventional and biologic disease-modifying antirheumatic drugs. Another four authors disclosed financial ties to Pfizer and other pharmaceutical companies. Five coauthors were employees of Pfizer.