OP0253 The JAK Inhibitor Tofacitinib Suppresses Synovial JAK1-STAT1 Signalling in Rheumatoid Arthritis

Evaluation of the Short-, Mid-, and Long-Term Effects of Tofacitinib on Lymphocytes in Patients With Rheumatoid Arthritis

OBJECTIVE

Tofacitinib is an oral JAK inhibitor for the treatment of rheumatoid arthritis (RA). Altered lymphocyte cell counts and a potential association with increased infection rates have been reported in RA patients treated with JAK inhibitors. This analysis was undertaken to evaluate the short-, mid-, and long-term effects of tofacitinib on lymphocytes and infection rates in patients with RA.

METHODS

In this post hoc analysis, absolute lymphocyte counts (ALCs) were obtained from phase III studies (12-24 months; n = 717-958) and phase I/II/III/long-term extension studies of tofacitinib (≤117 months) (All RA population; n = 7,061); lymphocyte subset counts (LSCs) were from phase II studies (1.5-6 months' exposure; n = 236-486), an ORAL Sequel vaccine substudy (~22 months; n = 198), and an ORAL Sequel lymphocyte substudy (~50 months; n = 55-1,035) of tofacitinib. The reversibility of ALC/LSC changes was evaluated. The relationship of ALC and LSC to infections was analyzed in the All RA population. The value of monitoring ALC alone was assessed by examining correlations between ALCs and LSCs.

RESULTS

Tofacitinib treatment resulted in an initial increase in ALC versus pretreatment baseline, which gradually declined to steady state by ~48 months. CD4+ and CD8+ T cell counts decreased over long-term treatment, and ALC and LSC changes were reversible upon treatment cessation. Patients with ALCs of <500 cells/mm³ had an increased risk of serious infections. There was no strong association between CD4+ T cell, CD8+ T cell, B cell, or natural killer cell counts and serious infection incidence rates. ALC and CD4+ or CD8+ T cell counts correlated well (R = 0.65-0.86).

CONCLUSION

Our findings indicate that monitoring of ALC alone appears to be adequate to assess infection risk in tofacitinib-treated patients with RA.

Safety and efficacy of tofacitinib, an oral janus kinase inhibitor, for the treatment of rheumatoid arthritis in open-label, longterm extension studies

OBJECTIVE

To describe the longterm safety and efficacy profile of tofacitinib in patients with moderate to severe active rheumatoid arthritis (RA).

METHODS

Data were pooled from 2 open-label studies (NCT00413699, NCT00661661) involving patients who had participated in qualifying phase I, II, or III index studies of tofacitinib. Safety data included over 60 months of observation; efficacy data are reported up to Month 48. Treatment was initiated with tofacitinib 5 or 10 mg twice daily. Primary endpoints were adverse events (AE) and laboratory safety data. Secondary endpoints included American College of Rheumatology (ACR) response rates, and Disease Activity Score (28 joints) (DAS28)-4[erythrocyte sedimentation rate (ESR)] and Health Assessment Questionnaire-Disability Index (HAQ-DI) assessments.

RESULTS

Overall, 4102 patients were treated for 5963 patient-years; mean (maximum) treatment duration was 531 (1844) days; 20.8% of patients discontinued treatment over 60 months. The most common AE were nasopharyngitis (12.7%) and upper respiratory tract infection (10.5%). Serious AE were reported in 15.4% of patients with an exposure-estimated incidence rate of 11.1 events/100 patient-years. Serious infections were reported in 4.5% of patients with an exposure-estimated incidence rate of 3.1 events/100 patient-years (95% CI: 2.66-3.55). Mean values for laboratory variables were stable over time and consistent with phase II and III studies. Persistent efficacy was demonstrated through Month 48, as measured by ACR response rate (ACR20/50/70) DAS28-4-ESR, and HAQ-DI. Safety and efficacy were similar for patients receiving tofacitinib as monotherapy or with background nonbiologic disease-modifying antirheumatic drugs.

CONCLUSION

Tofacitinib demonstrated consistent safety and persistent efficacy over 48 months in patients with RA.