• Data published today in the Am J Respir Crit Care Med highlight the novel mechanism of action of QTI571, which targets an underlying cause of PAH1
• Although the study failed to achieve the primary efficacy endpoint, a post hoc analysis showed statistically significant improvement in exercise function and haemodynamics among severe PAH patients1
• Phase III trial continues to recruit severe PAH patients to further investigate the efficacy and safety of QTI5712
Basel, July 9, 2010 – The proof of concept study to assess the safety, tolerability and efficacy of QTI571 (imatinib) in patients with pulmonary arterial hypertension (PAH) is published today in the American Journal of Respiratory and Critical Care Medicine (Am J Respir Crit Care Med, also known as The Blue Journal)1. QTI571, a tyrosine kinase inhibitor, was studied in patients with PAH not adequately controlled with currently licensed medications1. QTI571 significantly improved exercise capacity and pulmonary haemodynamics compared with placebo in patients with severe PAH1.
The 24-week proof of concept study, which involved 59 patients in the intention to treat (ITT) population, showed a significant decrease in pulmonary vascular resistance (PVR) (p=0.0004)1 and a significant increase in cardiac output (p=0.02)1 when compared with placebo, but the primary endpoint, mean 6-minute walking distance (6MWD), did not change significantly (p=0.21)1. However, a post-hoc subgroup analysis of the same data among severe patients demonstrated a significant increase in 6MWD1. This difference suggests that more severe PAH patients may respond better to QTI571. QTI571 was generally well-tolerated in PAH patients1. While nausea and headache were more common with QTI571 than with placebo, the majority of adverse events in both groups was deemed to be mild or moderate in intensity1.
An open-label extension study in 16 patients who had been treated with QTI571 for two to three years, looking at long-term safety and tolerability, was presented in May at the American Thoracic Society 2010 International Conference in New Orleans, USA. The initial improvement in exercise capacity (6MWD) was maintained in these patients over this period2.
As a result of the proof of concept findings, a Phase III trial (IMPRES: Imatinib in Pulmonary arterial hypertension, a Randomized Efficacy Study) continues to recruit 200 patients in 14 countries to further investigate the efficacy and safety of QTI571 in severe PAH2.
“These published results are encouraging, although we need to await the results of the ongoing Phase III trial to provide definitive evidence of safety and efficacy,’’ said Professor Ardeschir Ghofrani, MD, Giessen, Germany. “For patients with a poor prognosis and few remaining treatment options, clinicians need new approaches to treat this rapidly progressive disease.”
Current treatment options for PAH focus on vasodilation, whereas QTI571 primarily targets the underlying cause of the disease by counteracting uncontrolled growth of arterial smooth muscle cells. QTI571 works by inhibiting the activity of several proteins called tyrosine kinases, such as Bcr-Abl, c-KIT and platelet-derived growth factor receptor (PDGFR), which is thought to be involved in the progression of PAH. In patients with PAH, PDGFR may cause smooth muscle cells in the pulmonary arteries to multiply, resulting in the constriction of these arteries5.
“New treatment options for PAH need to go beyond treating symptoms and look at the underlying cause of the disease,” said Trevor Mundel, MD, Global Head of Development at Novartis Pharma AG. “These latest data reinforce the Novartis commitment to improving patients’ respiratory health, especially for patients with serious diseases such as PAH.”
PAH is a debilitating disease characterized by a marked and sustained elevation in pulmonary artery pressure6. PAH affects approximately 130,000 to 260,000 people worldwide5 and is progressive, leading to heart failure and death6. Apart from transplantation, there is no known cure for PAH and the goal of current treatments is to control symptoms of the disease7. The prognosis for many PAH patients is similar to that of some advanced cancers8. QTI571 is in the early stages of investigation as a potential therapy for PAH and is not approved in any market for treatment of PAH. Imatinib is approved under the trade names Gleevec®/Glivec® for the treatment of certain cancers.
*In this study severe PAH was defined as patients with a pulmonary vascular resistance (PVR) of ≥ 1,000.
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Last updated on: 27/08/2010
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