Schéma : The primary objective of this study is to provide extended access of momelotinib (MMB) in participants with primary myelofibrosis (PMF) or post-polycythemia vera or post-essential thrombocythemia myelofibrosis (Post-PV/ET MF) enrolled in studies GS-US-352-0101 (NCT01969838), GS-352-1214 (NCT02101268), GS-US-352-1154 (NCT02124746), who are currently receiving treatment with MMB (available as 100 mg, 150 mg and 200 mg tablets) and have not experienced progression of disease.

Study arms:
- Cohort 1: Study GS-US-352-0101
Participants will continue to receive the same dosage regimen as in the previous MMB study GS-US-352-0101 for a maximum duration of 96 weeks.
Intervention: Drug: MMB, Tablet(s) administered orally once daily
- Cohort 2: Study GS-US-352-1214
Participants will continue to receive the same dosage regimen as in the previous MMB study GS-US-352-1214 for a maximum duration of 96 weeks.
Intervention: Drug: MMB, Tablet(s) administered orally once daily
- Cohort 3: Study GS-US-352-1154
Participants will continue to receive the same dosage regimen as in the previous MMB study GS-US-352-1154 for a maximum duration of 96 weeks.
Intervention: Drug: MMB, Tablet(s) administered orally once daily

Current primary outcome:
Number of Participants Who Had Access to, and Received the Intervention [ Time Frame: Up to 96 Weeks ]