The tyrosine kinase inhibitor masitinib blunts airway inflammation and improves associated lung mechanics in a feline model of chronic allergic asthma.

BACKGROUND

Blockade of tyrosine kinase signaling by masitinib, a c-kit/PDGF receptor tyrosine kinase inhibitor, can modulate allergic airway inflammation, but effects on lung mechanics have not been well characterized. We hypothesized masitinib would decrease airway eosinophilia and consequently improve pulmonary mechanics in a feline allergic asthma model.

METHODS

Asthma was induced in 12 cats using Bermuda grass allergen (BGA). Cats received 50 mg/day oral masitinib or placebo. Bronchoalveolar lavage fluid (BALF) was analyzed for eosinophils, total protein (TP) and BGA-specific IgE. Ventilator-acquired mechanics after methacholine (MCh) challenge determined MCh concentration needed to increase baseline airway resistance by 200% (EC(200)R(aw)), positive end expiratory occlusion pressure (PEEP) and end inspiratory breath hold pressure (P(plat)). An inverse correlate of respiratory system compliance P(plat)-PEEP was also calculated. Data were analyzed using the Wilcoxon test, with one-tailed significance set at p < 0.1.

RESULTS

After 4 weeks, percent eosinophils in BALF was lower in masitinib-treated cats (7 ± 9%) versus controls (30 ± 27%, p = 0.023). BALF TP significantly differed (p = 0.047) between groups, decreasing with masitinib and increasing with placebo. BALF BGA-specific IgE was unaffected by masitinib. Both groups showed an improvement in EC(200)R(aw) (masitinib, p = 0.015; control, p = 0.078) but no significant change in PEEP after 4 weeks. Masitinib-treated cats demonstrated decreased P(plat) (p = 0.033) and P(plat)-PEEP (p = 0.075) at week 4, suggesting an improvement in respiratory compliance.

CONCLUSIONS

Masitinib reduced BALF eosinophilia and TP, indicating improved airway inflammation and edema, and improved P(plat) and P(plat)-PEEP, suggesting benefit to respiratory compliance influenced by airway inflammation/edema. Masitinib deserves further study in humans with chronic allergic asthma.