This study will be divided into 2 parts. Part 1 is a randomized, double-blind, single centre, placebo-controlled, single ascending dose (SAD) phase I study designed to assess the safety, tolerability, PK and PD (Pharmacodynamic) of TD139 in up to 36 healthy male subjects. Part 2 will be a randomized, double-blind, multi-centre, placebo-controlled, multiple dose expansion cohort, designed to assess the safety, tolerability, PK and PD of TD139 in up to 24 male subjects and female subjects of non child-bearing potential with IPF.