Will the Balance of JAK inhibition Yield Better Outcomes? Results of New JAK inhibitor - Peficitinib Save

Researchers from Keio University have published their results using novel JAK inhibitor peficitinib (ASP015K) as a monotherapy in moderate to severe RA patients. 

Peficitinib is a novel orally bioavailable JAK inhibitor in development for the treatment of RA. Peficitinib inhibits JAK1, JAK2, JAK3 and Tyk2 enzyme activities and has moderate selectivity for JAK3 inhibition. Increased interest in peficitinib is attributed to its potentially milder JAK 2 inhibitory effects on red blood cells and platelets. 

In this of 12-week, randomized, double-blind, placebo-controlled phase IIb trial 281 adult moderate to severe RA, patients were randomized receive to once-daily placebo or peficitinib 25,50,100 or 150 mg (without background DMARDs).

At week 12 the ACR20 response rates at week 12 were 10.7%, 23.6%, 31.6%, 54.5% and 65.5% in the placebo and peficitinib 25, 50, 100 and 150 mg groups, respectively (all statistically significant).
Treatment-emergent adverse events were similar between the placebo (64.3%), and peficitinib 25, 50, 100 and 150 mg roups (70.9%, 64.9%, 52.7% and 67.2% respectively). One death (cerebral haemorrhage) was reported in the peficitinib 50 mg group in a patient with hypertension and type 2 diabetes mellitus. Malignancy was not observed in any of the peficitinib groups. No cases of serious infections were reported. Herpes zoster occurred in four patients (two each in the peficitinib 25 and 100 mg groups); all of these events were assessed as grade 2.

Study concluded perificitib monotherapy provided statistically significant dose dependent clinical response and acceptable short-term safety profile after 12 weeks of treatment.