Tofacitinib versus etanercept or placebo in moderate-to-severe chronic plaque psoriasis: a phase 3 randomised non-inferiority trial

Type I/II cytokines, JAKs, and new strategies for treating autoimmune diseases

Cytokines are major drivers of autoimmunity, and biologic agents targeting cytokines have revolutionized the treatment of immune-mediated diseases. Despite the effectiveness of these drugs, they do not induce complete remission in all patients, prompting the development of alternative strategies - including targeting of intracellular signal transduction pathways downstream of cytokines. Many cytokines that bind type I and type II cytokine receptors are critical regulators of immune-mediated diseases and employ the Janus kinase (JAK) and signal transducer and activator of transcription (STAT) pathway to exert their effect. Pharmacological inhibition of JAKs blocks the actions of type I/II cytokines, and within the past 3 years therapeutic JAK inhibitors, or Jakinibs, have become available to rheumatologists. Jakinibs have proven effective for the treatment of rheumatoid arthritis and other inflammatory diseases. Adverse effects of these agents are largely related to their mode of action and include infections and hyperlipidemia. Jakinibs are currently being investigated for a number of new indications, and second-generation selective Jakinibs are being developed and tested. Targeting STATs could be a future avenue for the treatment of rheumatologic diseases, although substantial challenges remain. Nonetheless, the ability to therapeutically target intracellular signalling pathways has already created a new paradigm for the treatment of rheumatologic disease.

Secukinumab (AIN457) for the treatment of psoriasis

Psoriasis is a chronic inflammatory disease with a multifactorial origin that appears in patients with genetic predisposition and is induced by environmental factors, and characterized by alterations in the innate and adaptive immunity. IL-17A is one of the specific cytokines involved in the pathogenesis of psoriasis and its inhibition is highly effective in the treatment of patients with moderate and severe psoriasis. Secukinumab is a monoclonal antibody that specifically binds to IL-17A and inhibits the interaction to its receptor, and it has demonstrated its efficacy and safety in the treatment of psoriasis. Phase II and III clinical trials indicate that > 80% of the patients receiving secukinumab achieve Psoriasis Area Severity Index (PASI) 75 at week 12. In the Phase III efficacy of response and safety of two fixed secukinumab regimens in psoriasis trial, PASI 75 rates were 81.6% with 300 mg secukinumab, 71.6% with 150 mg secukinumab and 4.5% with placebo, and responses were maintained up to 52 weeks in the majority of patients. In the Phase III Full Year Investigative Examination Of Secukinumab versus Etanercept Using Two Dosing Regimens To Determine Efficacy in Psoriasis study, the efficacy of secukinumab was compared to etanercept. The results indicate that both doses of secukinumab (150 and 300 mg) showed superior efficacy compared with etanercept throughout the study; PASI 75 rates at week 12 were 77.1% with 300 mg secukinumab, 67% with 150 mg of secukinumab, 44% with etanercept and 4.9% with placebo. PASI 90 and PASI 100 were 54 and 24% with secukinumab 300 mg and 21 and 4% with etanercept at week 12. At week 52, PASI 90 continued to be higher in the secukinumab group (65%) compared with the etanercept group (33%). Regarding safety, the most common side effects were nasopharyngitis and headache. The rate of infections was higher with secukinumab than placebo. This was especially the case for Candida infections, which were more common in the secukinumab group (4.7% with secukinumab 300 mg and 2.3% with secukinumab 150 mg), but all cases were resolved with conventional treatment. Secukinumab is a well-tolerated treatment that has demonstrated efficacy in treating moderate-to-severe plaque psoriasis. Nevertheless, long-term studies are necessary to confirm Phase II and Phase III data.

Pharmacologic inhibition of JAK-STAT signaling promotes hair growth

Several forms of hair loss in humans are characterized by the inability of hair follicles to enter the growth phase (anagen) of the hair cycle after being arrested in the resting phase (telogen). Current pharmacologic therapies have been largely unsuccessful in targeting pathways that can be selectively modulated to induce entry into anagen. We show that topical treatment of mouse and human skin with small-molecule inhibitors of the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway results in rapid onset of anagen and subsequent hair growth. We show that JAK inhibition regulates the activation of key hair follicle populations such as the hair germ and improves the inductivity of cultured human dermal papilla cells by controlling a molecular signature enriched in intact, fully inductive dermal papillae. Our findings open new avenues for exploration of JAK-STAT inhibition for promotion of hair growth and highlight the role of this pathway in regulating the activation of hair follicle stem cells.

Effects of tofacitinib on lymphocyte sub-populations, CMV and EBV viral load in patients with plaque psoriasis

Background

Plaque psoriasis is a debilitating skin condition that affects approximately 2% of the adult population and for which there is currently no cure. Tofacitinib is an oral Janus kinase inhibitor that is being investigated for psoriasis.

Methods

The design of this study has been reported previously (NCT00678210). Patients with moderate to severe chronic plaque psoriasis received tofacitinib (2 mg, 5 mg, or 15 mg) or placebo, twice daily, for 12 weeks. Lymphocyte sub-populations, cytomegalovirus (CMV) and Epstein-Barr virus (EBV) DNA were measured at baseline and up to Week 12.

Results

Tofacitinib was associated with modest, dose-dependent percentage increases from baseline in median B cell count at Week 4 (24–68%) and Week 12 (18–43%) and percentage reductions from baseline in median natural killer cell count at Week 4 (11–40%). The proportion of patients with detectable CMV and EBV DNA (defined as >0 copies/500 ng total DNA) increased post-baseline in tofacitinib-treated patients. However, multivariate analyses found no relationship between changes in CMV or EBV viral load and changes in lymphocyte sub-populations or tofacitinib treatment.

Conclusions

Twelve weeks of treatment with tofacitinib had no clinically significant effects on CMV or EBV viral load, suggesting that lymphocyte sub-populations critical to the response to chronic viral infections and viral reactivation were not significantly affected. Replication of these findings during long-term use of tofacitinib will allow confirmation of this observation.