Efficacy and safety of ruxolitinib in patients with myelofibrosis: a retrospective and multicenter experience in Turkey

Background/aim

The aim of this study is to assess the efficacy and safety of ruxolitinib in patients with myelofibrosis.

Materials and methods

From 15 centers, 176 patients (53.4% male, 46.6% female) were retrospectively evaluated.

Results

The median age at ruxolitinib initiation was 62 (28–87) and 100 (56.8%) of all were diagnosed as PMF. Constitutional symptoms were observed in 84.7%. The median initiation dose of ruxolitinib was 30 mg (10–40). Dose change was made in 69 (39.2%) patients. Forty seven (35.6%) and 20 (15.2%) of 132 patients had hematological and nonhematological adverse events, respectively. The mean spleen sizes before and after ruxolitinib treatment were 219.67 ± 46.79 mm versus 199.49 ± 40.95 mm, respectively (p < 0.001). There was no correlation between baseline features and subsequent spleen response. Overall survival at 1-year was 89.5% and the median follow up was 10 (1–55) months. We could not show any relationship between survival and reduction in spleen size (p = 0.73).

Conclusion

We found ruxolitinib to be safe, well tolerated, and effective in real-life clinical practice in Turkey. Ruxolitinib dose titration can provide better responses in terms of not only clinical benefit but also for long term of ruxolitinib treatment.

Risk factors for infections and secondary malignancies in patients with a myeloproliferative neoplasm treated with ruxolitinib: a dual-center, propensity score-matched analysis

Ruxolitinib is a JAK1/2 inhibitor approved for the treatment of myelofibrosis (MF) and polycythemia vera (PV). Recent data have suggested the possibility of increased infectious and secondary malignancy rates in patients treated with ruxolitinib. We conducted a dual-center, retrospective study of 202 myeloproliferative neoplasm (MPN) patients receiving ruxolitinib and a control cohort of 73 ruxolitinib-naïve MPN patients. We utilized propensity score matching to analyze the primary outcome of development of any grade infection. Infections occurred in 38.4% of ruxolitinib-naïve patients and 42.6% of ruxolitinib-treated patients and were primarily grade 1/2. After propensity score weighting, there was no difference in risk of infection between ruxolitinib-treated and -naïve patients with MF (HR 1.15 [95% CI 0.80-1.65], p = .466) and non-MF MPNs (HR = 0.52 [95% CI 0.21-1.28, p = .152). These results suggest that there is not an increased risk of infection with ruxolitinib therapy.

IL-6 stimulation of DNA replication is JAK1/2 mediated in cross-talk with hyperactivated ERK1/2 signaling

Myeloproliferative neoplasms (MPNs) are developing resistance to therapy by JAK1/2 inhibitor ruxolitinib. To explore the mechanism of ruxolitinib's limited effect, we examined the JAK1/2 mediated induction of proliferation related ERK1/2 and AKT signaling by proinflammatory interleukin-6 (IL-6) in MPN granulocytes and JAK2V617F mutated human erythroleukemia (HEL) cells. We found that JAK1/2 or JAK2 inhibition prevented the IL-6 activation of STAT3 and AKT pathways in polycythemia vera and HEL cells. Further, we showed that these inhibitors also blocked the IL-6 activation of the AKT pathway in primary myelofibrosis (PMF). Only JAK1/2 inhibitor ruxolitinib largely activated ERK1/2 signaling in essential thrombocythemia and PMF (up to 4.6 fold), with a more prominent activation in JAK2V617F positive granulocytes. Regarding a cell cycle, we found that IL-6 reduction of HEL cells percentage in G2M phase was reversed by ruxolitinib (2.6 fold). Moreover, ruxolitinib potentiated apoptosis of PMF granulocytes (1.6 fold). Regarding DNA replication, we found that ruxolitinib prevented the IL-6 augmentation of MPN granulocytes frequency in the S phase of the cell cycle (up to 2.9 fold). The inflammatory stimulation induces a cross-talk between the proliferation linked pathways, where JAK1/2 inhibition is compensated by the activation of the ERK1/2 pathway during IL-6 stimulation of DNA replication.

Ruxolitinib-associated infections: A systematic review and meta-analysis

Ruxolitinib exerts immunosuppressive activity that may increase the risk of infectious complications. We performed a systematic review of the literature with the aim of estimating the risk of infections in patients treated with ruxolitinib. Studies were identified by electronic search of MEDLINE and EMBASE database. Differences in the incidence of infectious events between ruxolitinib and comparison groups were expressed as odds ratios (ORs) and 95% confidence intervals (95% CI). Five phase III randomized clinical trials (RCTs) (3 phase IIIa with their extended phase and 2 phase IIIb), 6 phase IV studies and 28 case reports were included in this systematic review. Ruxolitinib was associated with a statistically significant increased risk of herpes zoster infection compared to control group in 3 RCTs including patients with polycythemia vera (OR 7.39 [1.33, 41.07]) and in a pooled analysis of the extended phase IIIa RCTs (OR 5.20 [95%CI 1.27, 21.18]). In the larger phase IV post-marketing study, the incidence of the most frequent infections was 8% for herpes zoster, 6.1% for bronchitis and 6% for urinary tract infections. In the published case reports, the most frequent infections were tuberculosis (N = 10), hepatitis B reactivation (N = 5) and pneumocystis jeroveci infection (N = 2). Evidence is not solid enough to accurately estimate the risk of infection in ruxolitinib-treated patients. However, published data clearly suggest that the infection risk may be clinically relevant. Well-designed studies are warranted to evaluate the risk of ruxolitinib-associated infection, in order to identify the most appropriate antimicrobial prophylactic strategy.

Clinical use of ruxolitinib in an academic medical center in unselected patients with myeloproliferative neoplasms not on clinical study

Ruxolitinib is the only approved therapy for myelofibrosis (MF). However, its use in patients with myeloproliferative neoplasms (MPN) not participating in clinical studies has been poorly described. We reviewed the medical records of 45 patients (35 MF, 10 others) treated with ruxolitinib at our center, off clinical study, during the year after its approval. Patients had advanced features and were refractory to multiple therapies. Ruxolitinib was effective in reducing splenomegaly (51% response rate) and constitutional symptoms (42% response rate). It controlled blood counts in patients with polycythemia and thrombocythemia but was not effective in patients with non-classic MPNs. Ruxolitinib was an active therapy in patients previously treated with a JAK inhibitor and was safely combined with hypomethylating agents in patients with elevated blasts. Median overall survival was 24 months; 10 patients transformed to acute leukemia. Its use in combination with other active agents should be further explored in clinical studies.