Safety, pharmacokinetics and dose-response characteristics of GSK2269557, an inhaled PI3Kδ inhibitor under development for the treatment of COPD

BackgroundWhile current therapies reduce symptoms in chronic obstructive pulmonary disease (COPD) patients, substantial unmet need remains and novel treatments are highly desired. Phosphoinositide 3-kinase δ (PI3Kδ) is a lipid kinase specifically expressed in leucocytes and involved in their recruitment and activation. This study evaluated the safety, pharmacokinetics (PK) and dose-response characteristics of inhaled GSK2269557, a PI3Kδ inhibitor, in moderate-to-severe COPD patients with stable disease.MethodsIn this randomised, double-blind, placebo controlled, parallel group study, patients received once daily inhaled treatment with GSK2269557 1000 μg or placebo for 14 days (Part A, primary aim safety, N = 28 patients). In part B of the study (primary aim pharmacodynamic dose-response, N = 36 patients), GSK2269557 100, 200, 500, 700, 1000, 2000 μg or placebo was given for 14 days. In both Part A and B, GSK2269557 was added to the usual maintenance therapy. Safety, PK assessments and induced sputum collection for cytokine analysis were conducted at baseline and after 7 and 14 days of treatment. Adverse events (AEs) were monitored throughout.ResultsIn Part A, mean age was 61.7 years (SD 6.7), 29% were females, and mean FEV1% predicted was 59.7% (SD 11.4)2. In Part B, mean age was 63.3 years (SD 6.3), 44% were females, and mean FEV1% predicted was 56.5% (SD 11.5)2. GSK2269557 was well tolerated in both parts of the study; the most commonly reported AEs were cough and headache, with cough being reported with a greater incidence in the GSK2269557 groups vs. placebo (Part A: 19% vs. 14% and Part B: range of 0-80% for different doses vs. 0% on placebo). No drug-related serious AEs or clinically significant changes in any other safety parameters were reported. GSK2269557 was rapidly absorbed into plasma following all doses with a maximum peak at approximately 2 h. Following repeat administration, accumulation in plasma was approximately 2-3 fold from Day 1 to Day 7. At Day 14, relative to placebo, sputum interleukin (IL)-8 and IL-6 levels were reduced on average by 32% and 29% respectively after inhalation of GSK2269557 1000 μg in Part A. In Part B, although inhibition of both IL-8 and IL-6 levels was observed, the levels were variable and there was insufficient evidence to support a monotonic dose-response.ConclusionsIn this study, inhaled GSK2269557 had an acceptable safety profile for progression into larger studies in COPD patients. Moreover, inhalation of GSK2269557 resulted in suppression of sputum IL-8 and IL-6 levels, consistent with the known anti-inflammatory activity of a PI3Kδ inhibitor. Inhibition of inflammatory cytokines in the airway compartment may contribute to the potential therapeutic benefit of a PI3Kδ inhibitor in chronically inflamed COPD patients.