Significant improvement of bone marrow fibrosis in patients with chronic myeloproliferative neoplasms (CMPN) treated with ruxolitinib.

Abstract Ruxolitinib offers significant benefits for patients with myelofibrosis, particularly in enhancing survival rates and improving symptoms related to the disease, however, there are scarce reports of the effect of Ruxolitinib on the evolution of bone marrow fibrosis. Objectives: To assess the effect of long-term treatment with Ruxolitinib on bone marrow fibrosis of patients with chronic myeloproliferative neoplasms. Methods: We analyzed the bone marrow biopsies of 16 patients with CMPN, 8 men and 8 women were included with a median age of 63 years; 4 patients with primary Myelofibrosis, 3 with Myelofibrosis post Polycythemia vera and 9 with Myelofibrosis post essential Thrombocythemia. The median follow-up was 10 years. The patients started with a dose of 20 mg Ruxolitinib orally every 12 hours. The analysis was done before the start of treatment and 10 years after. Results: There was an important change, from fibrosis grade 3 to grade 1 in 6 patients (4 with thrombocythemia and 2 with Polycitemia). Five patients with fibrosis grade 2 changed to minimal fibrosis (all of them with thrombocythemia) and 5 patients remained with stable fibrosis (4 with primary myelofibrosis and 1 with polycythemia). Conclusions: A very significant decrease in the grade of myelofibrosis was found, mainly in patients with thrombocythemia and polycythemia (68.7 %) and in 5 patients (31.3 %) there was no progression. Although the sample of patients is small, the results are encouraging. Studies with a larger number of patients are required.