Standard care and investigational drugs in the treatment of myelofibrosis

Janus kinase inhibitor ruxolitinib in combination with nilotinib and prednisone in patients with myelofibrosis (RuNiC study): A phase Ib, multicenter study

This phase Ib, non-randomized, open-label study evaluates the safety and tolerability of ruxolitinib in combination with nilotinib and prednisone in patients with naïve or ruxolitinib-resistant myelofibrosis (MF). A total of 15 patients with primary or secondary MF received the study treatment; 13 patients had received prior ruxolitinib treatment (86.7%). Eight patients completed seven cycles (53.3%) and six patients completed twelve cycles of treatment (40%). All the patients experienced at least one adverse event (AE) during the study (the most common AEs were hyperglycemia, asthenia, and thrombocytopenia), and 14 patients registered at least one treatment-related AE (the most common treatment-related AEs were hyperglycemia (22.2%; three grade 3 cases). Five treatment-related serious AEs (SAEs) were reported in two patients (13.3%). No deaths were registered throughout the study. No dose-limiting toxicity was observed. Four out of fifteen (27%) patients experienced a 100% spleen size reduction at Cycle 7, and two additional patients achieved a >50% spleen size reduction, representing an overall response rate of 40% at Cycle 7. In conclusion, the tolerability of this combination was acceptable, and hyperglycemia was the most frequent treatment-related AE. Ruxolitinib in combination with nilotinib and prednisone showed relevant clinical activity in patients with MF. This trial was registered with EudraCT Number 2016-005214-21.

Safety and Efficacy of Ruxolitinib in Patients with Myelofibrosis and Low Platelet Counts (50 - 100 × 109/L): Final Analysis of an Open-Label Phase 2 Study

INTRODUCTION

Treatment options in patients with myelofibrosis (MF) presenting with thrombocytopenia are limited. Final results of the phase 2 study (NCT01348490) of ruxolitinib in patients with MF and low baseline platelet counts (50 - 100 × 10⁹/L) are reported.

PATIENTS AND METHODS

Patients received ruxolitinib 5 mg twice daily (BID), with optional up-titration to a maximum of 15 mg BID, provided platelet count remained ≥40 × 10⁹/L. Assessments included spleen volume and length, Total Symptom Score (TSS), quality of life, and safety.

RESULTS

Of 66 patients, 52 (78.8%) completed the first 24 weeks of treatment. Median (range) percentage change from baseline in spleen volume and TSS (coprimary endpoints) were -20.5% (-55.8% to 38.5%, n=51) and -39.8% (-98.6% to 226.4%, n=53), respectively; greatest median reductions were in the 10 mg BID final titrated dose group. Of patients achieving ≥35% or ≥10% reduction in spleen volume, 8/11 (72.7%) and 21/34 (61.8%), respectively, were in the 10 mg BID final titrated dose group. Thirty-seven of 65 patients (56.9%) had ≥20% improvement in TSS, and 35/66 patients (53.0%) were Patient Global Impression of Change responders. Treatment-emergent adverse events led to dose interruption in 17/66 patients (25.8%), most commonly thrombocytopenia (n=3).

CONCLUSION

A starting dose of ruxolitinib 5 mg BID with gradual up-titration and dose optimization based on hematologic parameters and response was efficacious and generally well-tolerated in patients with MF and low platelet counts. Median improvement in spleen volume and symptoms was greatest for patients receiving ruxolitinib 10 mg BID.

A Prognostic Model to Predict Survival After 6 Months of Ruxolitinib in Patients with Myelofibrosis

RUX dose, spleen response, and transfusion requirement in the first 6 months of RUX treatment predict overall survival in MF.

The RR6 model overcomes conventional risk stratification in RUX-treated MF.

Ruxolitinib (RUX) is extensively used in myelofibrosis (MF). Despite its early efficacy, most patients lose response over time and, after discontinuation, have a worse overall survival (OS). Currently, response criteria able to predict OS in RUX-treated patients are lacking, leading to uncertainty regarding the switch to second-line treatments. In this study, we investigated predictors of survival collected after 6 months of RUX in 209 MF patients participating in the real-world ambispective observational RUXOREL-MF study (NCT03959371). Multivariable analysis identified the following risk factors: (1) RUX dose <20 mg twice daily at baseline, months 3 and 6 (hazard ratio [HR], 1.79; 95% confidence interval [CI], 1.07-3.00; P = .03), (2) palpable spleen length reduction from baseline ≤30% at months 3 and 6 (HR, 2.26; 95% CI, 1.40-3.65; P = .0009), (3) red blood cell (RBC) transfusion need at months 3 and/or 6 (HR, 1.66; 95% CI, 0.95-2.88; P = .07), and (4) RBC transfusion need at all time points (ie, baseline and months 3 and 6; HR, 2.32; 95% CI, 1.19-4.54; P = .02). Hence, we developed a prognostic model, named Response to Ruxolitinib After 6 Months (RR6), dissecting 3 risk categories: low (median OS, not reached), intermediate (median OS, 61 months; 95% CI, 43-80), and high (median OS, 33 months; 95% CI, 21-50). The RR6 model was validated and confirmed in an external cohort comprised of 40 MF patients. In conclusion, the RR6 prognostic model allows for the early identification of RUX-treated MF patients with impaired survival who might benefit from a prompt treatment shift.