Study to Evaluate the Effect of GBT440 Administered to Subjects With IPF on Supplemental Oxygen at Rest

Inclusion Criteria:

- Documented diagnosis of IPF.

- Receiving supplemental oxygen for use at rest.

- Weight ≥ 40 kg.

- Male or female of child bearing potential willing and able to use highly effective
methods of contraception from study start to 30 days after the last dose of study
drug.

Exclusion Criteria:

- FEV1/FVC < 70%

- History of other interstitial lung diseases.

- Subject plans to begin or has commenced pulmonary rehabilitation within 30 days of
screening.

- Corticosteroid (> 10 mg per day of prednisone or an equivalent) administered for 7
days or longer, within 30 days of screening.

- Participated in another clinical trial of an investigational drug (or medical device)
within 30 days or 5-half-lives, whichever is longer, prior to screening, or is
currently participating in another trial of an investigational drug (or medical
device).

- Female who is breast-feeding or pregnant

- Current smoker or history of smoking within 3 months from screening