Abstract
Pulmonary arterial hypertension (PAH) results in progressive increases in pulmonary vascular resistance (PVR), right ventricular failure and death. There is currently no pharmacological cure for PAH, which is associated with low survival rates if patients do not receive effective specific therapy. Current treatment approaches focus on vasodilator outcomes. Imatinib has been associated with beneficial effects in some patients in a proof-of-concept study. The phase III, multinational, multicenter, double-blind, parallel-group IMPRES study evaluated the efficacy and safety and tolerability of imatinib to confirm these preliminary findings. Patients enrolled in IMPRES had severe symptomatic PAH on at least two PAH-specific therapies and PVR ≥800 dynes sec cm-5 and were randomized to imatinib or placebo. Treatment was initiated at a dose of 200 mg once daily, which was increased to 400 mg once daily after 2 weeks if well tolerated. Doses could then be reduced to 200 mg once daily if treatment was not well tolerated. The primary objective was to evaluate the efficacy of imatinib versus placebo for the change in 6-minute walk distance (6MWD) from baseline to week 24. Secondary objectives included evaluation of time to clinical worsening (all cause mortality, hospitalization for worsening PAH, worsening of World Health Organization [WHO] functional class or a 15% drop in 6MWD), safety and tolerability (including adverse events, laboratory data and vital signs), changes in pulmonary hemodynamics, changes in Borg dyspnea scores and pharmacokinetics. The study has enrolled a total of 202 patients. Findings from the IMPRES study will be available during 2011 and will be presented.
- © 2011 ERS