Momelotinib Versus Ruxolitinib in Subjects With Myelofibrosis

Key Inclusion Criteria:

- Palpable splenomegaly at least 5 cm below the left costal margin

- Confirmed diagnosis of PMF or post-PV/ET MF

- Requires myelofibrosis therapy, in the opinion of the investigator

- Classified as high risk OR intermediate-2 risk as defined by the International
Prognostic Scoring System (IPSS) for PMF, or intermediate-1 risk (IPSS) associated
with symptomatic splenomegaly, hepatomegaly, anemia (hemoglobin < 10.0 g/dL), and/or
unresponsive to available therapy

- Acceptable laboratory assessment obtained within 14 days prior to the first dose of
study drug:

- Absolute neutrophil count (ANC) ≥ 0.75 x 10^9/L in the absence of growth factor
in the prior 7 days

- Platelet Count ≥ 50 x 10^9/L (≥ 100 x 10^9/L if aspartate aminotransferase [AST]
or alanine aminotransferase [ALT] is ≥ 2 x the upper limit of the normal range
[ULN]) in the absence of platelet transfusion(s) or thrombopoietin mimetics in
the prior 7 days

- Peripheral blood blast count < 10%

- AST and ALT ≤ 3 x ULN (≤ 5 x ULN if liver is involved by extramedullary
hematopoiesis as judged by the investigator or if related to iron chelator
therapy that was started within the prior 60 days)

- Calculated creatinine clearance (CrCL) of ≥ 45 mL/min

- Direct bilirubin ≤ 2.0 x ULN

- Life expectancy of > 24 weeks

- Males and females of childbearing potential must agree to use protocol-specified
method(s) of contraception

- Females who are nursing must agree to discontinue nursing before the first dose of
study drug

- Able to understand and willing to sign the informed consent form

Key Exclusion Criteria:

- Prior splenectomy

- Splenic irradiation within 3 months prior to the first dose of study drug

- Eligible for allogeneic bone marrow or stem cell transplantation

- Uncontrolled inter-current illness, per protocol.

- Known positive status for human immunodeficiency virus (HIV)

- Chronic active or acute viral hepatitis A, B, or C infection, or a hepatitis B or C
carrier

- Prior use of a JAK1 or JAK2 inhibitor

- Use of chemotherapy, immunomodulating therapy, biologic therapy, radiation therapy, or
investigational therapy within 4 weeks of the first dose of study drug

- Presence of peripheral neuropathy ≥ Common Terminology Criteria for Adverse Events
(CTCAE) Grade 2

- Unwilling or unable to undergo a magnetic resonance imaging (MRI) or computed
tomography (CT) scan

Note: Other protocol defined Inclusion/Exclusion criteria may apply.