Study to Evaluate the Safety and Tolerability of GBT440 Administered to Subjects With IPF

Inclusion Criteria:

- Documented diagnosis of IPF.

- Oxygen desaturation with exercise.

- Completion of the baseline 6MWT

- Weight ≥ 50 kg

- Male or female of child bearing potential willing and able to use highly effective
methods of contraception from study start to 3 months after the last dose of study
drug.

Exclusion Criteria:

- FEV1/FVC < 70%.

- Subjects on supplemental oxygen therapy at rest.

- History of other interstitial lung diseases.

- Significant polycythemia.

- Female who is breast-feeding or pregnant.

- Known current malignancy or history of malignancy within the last 2 years prior to
screening.

- Use of cytotoxic and/or immunosuppressant medications within 30 days screening.

- Hospitalization due to an exacerbation of IPF within 30 days of screening

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

- Corticosteroids (> 10 mg per day of prednisone or an equivalent) within 30 days of
screening.

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

- Currently or, in the opinion of the investigator, soon to be listed for lung
transplant.

- History of unstable or deteriorating cardiac or pulmonary disease (other than IPF)
within 6 months of screening.

- Any condition possibly affecting drug absorption.

- 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).

- Subject who, for any reason, is deemed by the investigator to be inappropriate for
this study.