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Efficacy and Safety of PF-06651600 (Ritlecitinib), a Novel JAK3/TEC Inhibitor, in Patients With Moderate-to-Severe
Michael F Robinson1, Nemanja Damjanov2, Bojana Stamenkovic3
1California Medical Research Associates, Northridge.
Objective:
To evaluate the efficacy and safety of PF-06651600 (ritlecitinib), an irreversible inhibitor of JAK3 and the tyrosine kinase expressed in hepatocellular carcinoma (TEC) kinase family, in comparison with placebo in patients with rheumatoid arthritis (RA).
Methods:
An 8-week, phase II, double-blind, parallel-group study was conducted. Seventy patients who were seropositive for anti-citrullinated protein antibodies and/or rheumatoid factor were randomized 3:2 to receive oral PF-06651600 (200 mg once daily) or placebo for 8 weeks. Eligible patients had an inadequate response to methotrexate, and the study design allowed up to 50% of patients to have previously received 1 tumor necrosis factor inhibitor that was inadequately effective and/or not tolerated. The primary end point was change from baseline in the Simplified Disease Activity Index (SDAI) score at week 8, assessed by Bayesian analysis using an informative prior distribution for placebo response.
Results:
Mean change from baseline in the SDAI score at week 8 was greater in the PF-06651600 group (-26.1 [95% credible interval -29.7, -22.4]) than in the placebo group (-16.8 [95% credible interval -20.9, -12.7]; P < 0.001). Most adverse events (AEs) were mild in severity, and no treatment-related serious AEs, severe AEs, or deaths were reported. The most common classes of AE were infections and infestations as well as skin and subcutaneous tissue disorders; there was 1 mild case of herpes simplex in the PF-06651600 group that was considered to be treatment related, which resolved within 3 days without study treatment discontinuation or antiviral therapy.
Conclusion:
Treatment with the oral JAK3/TEC inhibitor PF-06651600 (200 mg once daily) was associated with significant improvements in RA disease activity and was generally well-tolerated in this small 8-week study.
Insights
PF-06651600 (ritlecitinib), an oral JAK3/TEC inhibitor, significantly improved rheumatoid arthritis (RA) disease activity in an 8-week study. The treatment was well-tolerated with mild adverse events, showing promise for RA management.
Area of Science:
- Rheumatology
- Immunology
- Pharmacology
Background:
- Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by joint inflammation and damage.
- Current RA treatments, including methotrexate and TNF inhibitors, do not provide adequate relief for all patients.
- Targeting specific signaling pathways, such as JAK/STAT, offers a potential therapeutic strategy for RA.
Purpose of the Study:
- To evaluate the efficacy and safety of PF-06651600 (ritlecitinib), an irreversible JAK3 and TEC kinase inhibitor, compared to placebo in patients with RA.
- To assess the impact of PF-06651600 on disease activity as measured by the Simplified Disease Activity Index (SDAI).
Main Methods:
- An 8-week, phase II, double-blind, randomized, placebo-controlled study.
- Seventy RA patients with inadequate response to methotrexate received either PF-06651600 (200 mg once daily) or placebo.
- The primary endpoint was the change from baseline in SDAI score at week 8.
Main Results:
- PF-06651600 demonstrated a significantly greater mean reduction in SDAI score from baseline at week 8 compared to placebo (-26.1 vs. -16.8, P < 0.001).
- Adverse events were predominantly mild, with no treatment-related serious adverse events, severe adverse events, or deaths reported.
- The most common adverse events were infections and infestations, and skin/subcutaneous tissue disorders.
Conclusions:
- Oral PF-06651600 (200 mg once daily) significantly improved disease activity in RA patients over 8 weeks.
- The JAK3/TEC inhibitor was generally well-tolerated in this study population.
- PF-06651600 shows potential as a new therapeutic option for managing rheumatoid arthritis.
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