Design and rationale for the prospective treatment efficacy in IPF using genotype for NAC selection (PRECISIONS) clinical trial

Background: Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with few treatment options. N-acetylcysteine (NAC) is a well-tolerated, inexpensive treatment with antioxidant and anti-fibrotic properties. The National Heart, Lung, and Blood Institute (NHLBI)-sponsored PANTHER (Prednisone Azathioprine and NAC therapy in IPF) trial confirmed the harmful effects of immunosuppression in IPF, and did not show a benefit to treatment with NAC. However, a post hoc analysis revealed a potential beneficial effect of NAC in a subgroup of individuals carrying a specific genetic variant, TOLLIP rs3750920 TT genotype, present in about 25% of patients with IPF. Here, we present the design and rationale for the Phase III, multi-center, randomized, double-blind, placebo-controlled Prospective Treatment Efficacy in IPF Using Genotype for NAC Selection (PRECISIONS) clinical trial. Methods: The PRECISIONS trial will randomize 200 patients with IPF and the TOLLIP rs3750920 TT genotype 1:1 to oral N-acetylcysteine (600 mg tablets taken three times a day) or placebo for a 24-month duration. The primary endpoint is the composite of time to 10% relative decline in forced vital capacity (FVC), first respiratory hospitalization, lung transplantation, or death from any cause. Secondary endpoints include change in patient-reported outcome scores and proportion of participants with treatment-emergent adverse events. Biospecimens, including blood, buccal, and fecal will be collected longitudinally for future research purposes. Study participants will be offered enrollment in a home spirometry substudy, which explores time to 10% relative FVC decline measured at home, and its comparison with study visit FVC. Discussion: The sentinel observation of a potential pharmacogenetic interaction between NAC and TOLLIP polymorphism highlights the urgent, unmet need for better, molecularly focused, and precise therapeutic strategies in IPF. The PRECISIONS clinical trial is the first study to use molecularly-focused techniques to identify patients with IPF most likely to benefit from treatment. PRECISIONS has the potential to shift the paradigm in how trials in this condition are designed and executed, and is the first step toward personalized medicine for patients with IPF. Trial Registration ClinicalTrials.gov identifier: NCT04300920. Registered March 9, 2020. https://clinicaltrials.gov/ct2/show/NCT04300920