Cell survival assay is performed using MTT. Briefly, K562, KCL22, and THP-1 cells (1×10⁵ cells/well) are plated onto 96-well microplates and treated with or without IMA (0.06-1.0 μM) and/or Tofacitinib (10-1,000 nM) or RUX (10-1,000 nM) for 72 h at 37°C in a humidified 5% (v/v) CO₂ atmosphere. The medium (200 μL) is then incubated with 10 μL of 5 mg/ml MTT solution for 4 h at 37°C. After being centrifuged at 352 g for 5 min, the culture medium is removed, and 100 μL of DMSO are added to each well to dissolve the formazan. Absorbance is measured at 570 nm using a microplate reader. The results are expressed as percentages^[4].

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

Mice^[2]
Female BALB/c mice (6-8 weeks old) are used. Mice receive Tofacitinib in PEG300 (100 mg/mL) or vehicle alone (PEG300) by osmotic pump infusion (0.25 μL/hour, 28 days). Four days prior to immunization, mice are anesthetized and their dorsal surface is shaved. A one cm incision is made on the back to create a subcutaneous pocket and insert the pump. The incision site is closed with wound clips. Mice are injected weekly (i.p.) with SS1P recombinant immunotoxin (RIT; 5 μg/mouse) beginning on day 0; control mice received injections of saline alone. Every week before SS1P or vehicle immunization, 50 μL of blood is drawn to obtain serum samples. Sera are stored at -80°C until analyzed.
Rats^[3]
Adjuvant-induced arthritis (AIA) is induced in female Lewis rats. Rats are randomized according to hind paw volume and assigned to Tofacitinib or vehicle treatment regimens. Groups of 7-8 rats per treatment group, and normal naive rats (n=4 per group), are euthanized either 4 hours, 4 days, or 7 days after beginning treatment (days 16, 20, and 23 after immunization, respectively). Once-daily oral administration of vehicle or Tofacitinib (6.2 mg/kg) is initiated on day 16 following immunization and continued through day 23. Paw volumes are reassessed 4 and 7 days after the beginning of treatment (days 20 and 23 after immunization, respectively). For micro-computed tomography (micro-CT) imaging, as well as tartrate-resistant acid phosphatase (TRAP) staining in paw tissue, AIA is induced in a separate cohort of Lewis rats.

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

• [1]. Jiang JK, et al. Examining the chirality, conformation and selective kinase inhibition of 3-((3R,4R)-4-methyl-3-(methyl(7H-pyrrolo[2,3-d]pyrimidin-4-yl)amino)piperidin-1-yl)-3-oxopropanenitrile (CP-690,550). J Med Chem. 2008 Dec 25;51(24):8012-8.  [Content Brief]

  [2]. Onda M, et al. Tofacitinib suppresses antibody responses to protein therapeutics in murine hosts. J Immunol. 2014 Jul 1;193(1):48-55.  [Content Brief]

  [3]. LaBranche TP, et al. JAK inhibition with tofacitinib suppresses arthritic joint structural damage through decreased RANKL production. Arthritis Rheum. 2012 Nov;64(11):3531-42.  [Content Brief]

  [4]. Yagi K, et al. Pharmacological inhibition of JAK3 enhances the antitumor activity of STI571 in human chronic myeloid leukemia. Eur J Pharmacol. 2018 Apr 15;825:28-33.  [Content Brief]