This phase II trial studies the long-term side effects of ruxolitinib in treating patients with myelofibrosis. Collecting data about the long-term safety and tolerability of ruxolitinib may better help future patients with myelofibrosis.

PRIMARY OBJECTIVES:

I. To collect long term safety and tolerability data in patients with myelofibrosis previously treated with ruxolitinib on protocol 2007-0169.

OUTLINE:

Patients continue to receive ruxolitinib orally (PO) once daily (QD) or twice daily (BID). Cycles repeat every 28 days in the absence of disease progression or unacceptable toxicity. Patients undergo follow-up assessment for safety over 10 minutes every 3 cycles.

Inclusion Criteria:

1. Currently enrolled in study 2007-0169 and benefiting from therapy as determined by treating physician
2. Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2 at enrollment of this study
3. Ability and agreement to attend protocol-specified visits at the study site
4. Able to comprehend and willing to sign the informed consent form
5. Negative pregnancy test in females of childbearing potential; male patients with female partners of child-bearing potential and female patients of childbearing potential are required to use two forms of acceptable contraception, including one barrier method, during their participation in the study and for 30 days following last dose; acceptable forms of contraception include 1 highly effective method such as an intrauterine device (IUD), hormonal (birth control pills, injections, or implants), tubal ligation, or partner's vasectomy and at least 1 additional approved barrier method such as a latex condom, diaphragm, or cervical cap; female patients of childbearing potential must not be breast-feeding or planning to breast feed and must have a negative pregnancy test 7 days before first study treatment

Exclusion Criteria:

1. none

Up to the date of failure or death from any cause, up to 7 years, 3 months and 24 days.