Effects Of CP-690,550 (Tasocitinib) On Cholesterol Metabolism In Patients With Active Rheumatoid Arthritis

• High-density Lipoprotein Cholesterol (HDL-C) Concentration at Baseline [ Time Frame: Baseline ] [ Designated as safety issue: No ]
  Blood level of HDL-C was measured following a 12-hours fasting.
• High-density Lipoprotein Cholesterol (HDL-C) Concentration at Week 6 [ Time Frame: Week 6 ] [ Designated as safety issue: No ]
  Blood level of HDL-C was measured following a 12-hours fasting.
• Cholesterol Ester Production Rate at Baseline [ Time Frame: Baseline ] [ Designated as safety issue: No ]
  Cholesterol ester production rate was calculated using a 3-pool model with a simulation, analysis and modeling (SAAM II) program.
• Cholesterol Ester Production Rate at Week 6 [ Time Frame: Week 6 ] [ Designated as safety issue: No ]
  Cholesterol ester production rate was calculated using a 3-pool model with a simulation, analysis and modeling (SAAM II) program.

• High Density Lipoprotein Apolipoprotein A1 (HDL-apoA1) production rate (mg/kg/hr) and fractional catabolic rate (%/hr) [ Time Frame: 6 weeks ] [ Designated as safety issue: No ]
• High Density Lipoproteins (HDL), Low Density Lipoproteins (LDL) and total cholesterol concentrations [ Time Frame: 6 weeks ] [ Designated as safety issue: No ]
• Low Density Lipoprotein Apolipoprotein B (LDL-apoB) production rate (mg/kg/hr) and fractional catabolic rate (%/hr) [ Time Frame: 6 weeks ] [ Designated as safety issue: No ]
• Cholesterol ester production rate (mg/kg/hr) and cholesterol ester fractional catabolic rate (%/hr) [ Time Frame: 6 weeks ] [ Designated as safety issue: No ]

• Low-density Lipoprotein Cholesterol (LDL-C) and Total Cholesterol Concentration [ Time Frame: Baseline, Week 6 ] [ Designated as safety issue: No ]
  Blood level of LDL-C and total cholesterol (TC) was measured following a 12-hours fasting.
• Cholesterol Ester Fractional Catabolic Rate [ Time Frame: Baseline, Week 6 ] [ Designated as safety issue: No ]
  Cholesterol ester fractional catabolic rate were calculated using a 3-pool model with a simulation, analysis and modeling (SAAM II) program. Fractional catabolic rate was the percentage of cholesterol ester which was replaced, transferred or lost per unit of time.
• Low-density Lipoprotein Associated With Apolipoprotein B (LDL-apoB) Production Rate [ Time Frame: Baseline, Week 6 ] [ Designated as safety issue: No ]
  LDL-apoB production rate were calculated using a 3-pool model with a simulation, analysis and modeling (SAAM II) program.
• Low-density Lipoprotein Associated With Apolipoprotein B (LDL-apoB) Fractional Catabolic Rate [ Time Frame: Baseline, Week 6 ] [ Designated as safety issue: No ]
  Fractional catabolic rate for LDL ApoB were calculated using the 13 carbon (13C) isotopic enrichment of very low density lipoprotein (VLDL) as the limiting value. Isotope 13C in plasma was measured using Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry (GC-C-IRMS).
• High-density Lipoprotein Associated With Apolipoprotein A1 (HDL-apoA1) Production Rate [ Time Frame: Baseline, Week 6 ] [ Designated as safety issue: No ]
  HDL-apoA1 production rate were calculated using a 3-pool model with a simulation, analysis and modeling (SAAM II) program.
• High-density Lipoprotein Associated With Apolipoprotein A1 (HDL-apoA1) Fractional Catabolic Rate [ Time Frame: Baseline, Week 6 ] [ Designated as safety issue: No ]
  Fractional catabolic rate for HDL-apoA1 were calculated using the 13C isotopic enrichment of VLDL as the limiting value. Isotope 13C in plasma was measured using GC-C-IRMS.
• Cholesterol Efflux Rate [ Time Frame: Baseline, Week 6 ] [ Designated as safety issue: No ]
  Cholesterol efflux rate was measured using isotope dilution method in which rate of appearance of isotope 13C-free cholesterol in plasma representing whole body efflux from tissues was assessed. Isotope 13C in plasma was measured using GC-C-IRMS.

• Incidence and severity of adverse events [ Time Frame: 6 weeks ] [ Designated as safety issue: Yes ]
• Incidence and severity of clinical laboratory abnormalities [ Time Frame: 6 weeks ] [ Designated as safety issue: Yes ]
• Mean change from baseline in vital signs (blood pressure, heart rate, and temperature) measurements [ Time Frame: 6 weeks ] [ Designated as safety issue: Yes ]

The purpose of study is to explore the effect of CP-690,550 (tasocitinib) on cholesterol metabolism in patients with active rheumatoid arthritis (RA).

• Experimental: CP-690,550 (tasocitinib) 10 mg twice daily (BID)
  Intervention: Drug: CP-690,550 (tasocitinib)
• No Intervention: Healthy Volunteers
  No intervention

Inclusion Criteria:

• Males or females, 18 years of age or older with active rheumatoid arthritis; Or male and female healthy volunteers 18 years of age and older

Exclusion Criteria:

• Pregnant or lactating women
• Clinically significant systemic disease (other than RA for RA arm)
• Use of lipid-regulating agents