Long-term safety and exploratory efficacy of fevipiprant in patients with inadequately controlled asthma: the SPIRIT randomised clinical trial

The prostaglandin D (PGD ) receptor 2 (DP receptor) pathway is an important regulator of the inflammatory cascade in asthma, which can be stimulated by allergic or non-allergic triggers. Fevipiprant is an oral, non-steroidal, highly selective, reversible antagonist of the DP receptor that inhibits the binding of PGD and its metabolites. SPIRIT, a 2-treatment period (52-week, double-blind and optional 104-week single-blind), randomised, placebo-controlled, multicentre, parallel-group study, assessed the long-term safety of fevipiprant (150 mg and 450 mg o.d.) added to standard of care in patients ≥ 12 years with uncontrolled asthma. Stratified block randomisation was used. Patients were randomised in an approximate ratio of 3:3:1 (fevipiprant 150 mg, fevipiprant 450 mg or placebo). Patients were either newly enrolled or had participated in a previous fevipiprant Phase 3 trial. Primary endpoints were: time-to-first treatment emergent adverse event (AE); serious AE; and AE leading to discontinuation from study treatment. Data from both treatment periods were combined for analyses. Data were collected during study site visits. In total, 1093 patients were randomised to receive fevipiprant 150 mg, 1085 to fevipiprant 450 mg, and 360 to placebo. Overall, 1184 patients had ≥ 52 weeks' treatment, while 163 received ≥ 104 weeks' treatment. Both doses were well tolerated, with a safety profile similar to placebo both in new patients and in those enrolled from previous studies. In exploratory analyses, reduced rates of moderate-to-severe asthma exacerbations, increased time-to-first moderate-to-severe asthma exacerbation and improved FEV were observed for both doses of fevipiprant versus placebo; these were without multiplicity adjustment and should be interpreted with caution. SPIRIT was terminated early, on 16 December 2019, by the Sponsor. In patients with uncontrolled asthma, the addition of fevipiprant had a favourable long-term safety profile. Clinicaltrials.gov, NCT03052517, prospectively registered 23 January 2017, https://clinicaltrials.gov/ct2/show/NCT03052517 .