A Study of Parsaclisib in Combination With Ruxolitinib in Subjects With Myelofibrosis

Inclusion Criteria:

- Diagnosis of primary myelofibrosis, post-polycythemia vera myelofibrosis, or
post-essential thrombocythemia myelofibrosis

- Palpable spleen of > 10 cm below the left subcostal margin on physical examination at
the screening visit OR

- Palpable splenomegaly of 5 to 10 cm below left subcostal margin on physical exam AND
active symptoms of MF at the screening visit as demonstrated by presence of 1 symptom
score ≥ 5 or 2 symptom scores ≥ 3 using the Screening Symptom Form

- Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2

Exclusion Criteria:

- Use of experimental drug therapy for myelofibrosis, or any other standard drug (eg,
danazol, hydroxyurea, etc) with the exception of ruxolitinib within 6 months of
starting study (combination) therapy and/or lack of recovery from all toxicities from
previous therapy (except ruxolitinib) to Grade 1 or better

- Inability to swallow food or any condition of the upper gastrointestinal tract that
precludes administration of oral medications

- Unwillingness to be transfused with blood components

- Recent history of inadequate bone marrow reserve as demonstrated by the following:

- Platelet count < 50 × 10^9/L in the 4 weeks before screening or platelet
transfusion(s) within 8 weeks before screening

- Absolute neutrophil count levels < 0.5 × 10^9/L in the 4 weeks before screening

- Subjects with peripheral blood blast count of > 10% at the screening or baseline
hematology assessments

- Subjects who are not willing to receive red blood cell (RBC) transfusions to
treat low hemoglobin levels

- Inadequate liver function at screening as demonstrated by the following:

- Direct bilirubin ≥ 2.0 × the upper limit of laboratory normal (ULN). (NOTE:
direct bilirubin will only be determined if total bilirubin is ≥ 2.0 × ULN)

- alanine aminotransferase (ALT) or aspartate aminotransferase (AST) > 2.5 × ULN

- Inadequate renal function at screening as demonstrated by creatinine clearance < 50
mL/min or glomerular filtration rate < 50 mL/min/1.73 m^2