Jakafi® (ruxolitinib) prolongs survival in patients with intermediate- or high-risk primary myelofibrosis compared with patients who receive conventional therapy, according to the results of a study published in the journal Blood.

Primary myelofibrosis is a type of blood cancer known as a myeloproliferative neoplasm. It involves the abnormal development and function of bone marrow cells that produce blood cells and leads to the formation of scar tissue in the bone marrow. This can cause anemia, enlargement of the spleen and liver, fatigue, and other problems. In some patients with myelofibrosis, the condition progresses to acute myeloid leukemia.

Jakafi—approved in 2011—is currently the only drug that has been approved specifically for myelofibrosis diseases. It is a targeted therapy known as a JAK inhibitor. Jakafi can help to relieve the signs and symptoms of myelofibrosis, such as enlargement of the spleen, night sweats, itching, and bone or muscle pain.

The international prognostic scoring system (IPSS) is a risk assessment tool used upon diagnosis of primary myelofibrosis. (During follow-up, the dynamic IPSS (DIPSS) and DIPSS-plus time-dependent models are used.) Patients with primary myelofibrosis who are categorized with intermediate-2 or high IPSS risk have a median life expectancy of 4 years or less.

There have been two prospective, randomized, phase III studies of Jakafi. The COMFORT-1 study compared Jakafi and placebo, while the COMFORT-2 study compared Jakafi and best available therapy. Both of these studies allowed crossover to Jakafi.

In the current study, researchers analyzed the cohort of Jakafi-naive patients used for developing the DIPSS. They compared survival from diagnosis of 100 PMF patients who received Jakafi (COMFORT-2 cohort) with that of a comparable group of 350 conventionally treated PMF patients (DIPSS cohort).

The analysis revealed that PMF patients with higher IPSS risks who receive Jakafi survive longer than those who receive conventional therapy. Median survival was 5 years in the COMFORT-2 cohort compared with 3.5 years in the DIPSS cohort. The 8-year survival probability from initial diagnosis was 32.2 percent for the COMFORT-2 cohort and 15.9% for the DIPSS cohort. After adjusting for age at diagnosis and IPSS risk at the time of entering the analysis, Jakafi still maintained an effect on survival.

The researchers concluded that patients treated with Jakafi at some point during their disease history survived longer than those who continued with conventional treatment throughout the whole duration of their disease. As a result, they speculated that Jakafi might affect the natural history of the disease.


Passamonti F, Maffioli M, Cervantes F, et al: Impact of ruxolitinib on the natural history of primary myelofibrosis: a comparison of the DIPSS and the COMFORT-2 cohorts. Blood. 2014; 123(12): 1833-1835.


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