Moving Beyond Ruxolitinib Failure in Myelofibrosis: Evolving Strategies for Second Line Therapy

Disease Phenotype Significantly Influences the Outcome After Discontinuation of Ruxolitinib in Chronic Phase Myelofibrosis

INTRODUCTION

In patients with myelofibrosis (MF), overall survival (OS) after ruxolitinib discontinuation is poor, with leukemic transformation, clonal evolution and thrombocytopenia as the main factors worsening prognosis.

PATIENTS AND METHODS

To assess the impact of disease phenotype on outcome after ruxolitinib discontinuation in chronic phase patients, we performed a sub-analysis of the "RUX-MF" study (NCT06516406), which now includes 1055 MF patients who received ruxolitinib in a real-life context.

RESULTS

After a median follow-up of 3.3 years, 397 patients discontinued ruxolitinib therapy while in chronic phase. At treatment end, 208 patients (52.4%) had a severely cytopenic phenotype (defined as platelets < 100 × 109/L and/or hemoglobin < 8 g/dL); among the remaining myeloproliferative 189 patients, 97 had no cytopenia (51.3%) and 92 (48.7%) had mild anemia only (hemoglobin between 8 and 10 g/dL). Overall, 175 patients (44.1%) had a large splenomegaly (palpable at ≥ 10 cm below costal margin). After ruxolitinib discontinuation, 3-year OS was 33.4% in severely cytopenic and 54.4% in myeloproliferative patients (P < .001); this was confirmed after adjustment for risk categories. Noncytopenic and mildly anemic patients had comparable OS (P = .73). Patients with large splenomegaly had significantly poorer OS compared to nonsplenomegalic patients (OS: 33.5% vs. 51.6% P = .01). Large splenomegaly confirmed its negative prognostic impact on OS of patients with myeloproliferative MF (60.7% vs. 44.5%, P = .05). In patients with severe cytopenia, the presence of a large splenomegaly did not influence OS (41.7% vs. 26.1%, P = .26).

CONCLUSIONS

Cytopenic phenotype and large splenomegaly in myeloproliferative MF are key prognostic determinants of outcome after ruxolitinib discontinuation.

Electrochemical Behavior of Janus Kinase Inhibitor Ruxolitinib at a Taurine-Electropolymerized Carbon Paste Electrode: Insights into Sensing Mechanisms

Ruxolitinib (RXL) is a Janus kinase inhibitor used for treating intermediate- or high-risk myelofibrosis. This study presents an electrode modified with electrochemically polymerized taurine on a carbon paste electrode via cyclic voltammetry (CV). The surface characterization of the poly(taurine)-CP electrode was evaluated by using electrochemical (electrochemical impedance spectroscopy─EIS, CV), morphological (scanning electron microscope─SEM), and spectroscopic (Fourier-transform infrared spectroscopy─FT-IR) techniques. Under optimized conditions, RXL exhibited good linearity within the 0.01-1.0 μM concentration range, with a limit of detection (LOD) of 0.005 μM. The proposed electrochemical sensor demonstrated excellent selectivity, accuracy, precision, and repeatability. Furthermore, it effectively detected RXL in human urine and pharmaceutical samples.

Advances in pharmacotherapy for myelofibrosis: what is the current state of play?

INTRODUCTION

The introduction of the first JAK inhibitor (JAKi) ruxolitinib 10 years ago represented a pivotal advancement in myelofibrosis (MF) treatment, mostly in terms of spleen and symptoms response. Nowadays three more JAKi, fedratinib, pacritinib, and momelotinib, are available for both ruxolitinib-resistant and naïve patients. Moreover, many drugs are currently being investigated, both alone and in combination with JAKi.

AREAS COVERED

In this review we discuss the long-term data of ruxolitinib and more recent evidence coming from clinical trials of fedratinib, pacritinib, and momelotinib, used as first- or second-line MF therapy. More, focus is set on data from non-JAKi drugs, such as the quite extensively studied BET-inhibitors (pelabresib) and BCL-inhibitors (navitoclax), novel target therapies, and drugs aimed to improve anemia, still representing a major determinant of reduced survival in MF.

EXPERT OPINION

It's now evident that JAKi monotherapy, though clinically effective, is rarely able to change MF natural history; novel drugs are promising but long-term data are inevitably lacking. We feel that soon MF treatment will require clinicians to select the most appropriate JAKi inhibitor, based on patient characteristics, associating either front-line or in case of early suboptimal response, non-JAKi drugs with the aim to pursue disease modification.

Association of Myelofibrosis Phenotypes with Clinical Manifestations, Molecular Profiles, and Treatments

Myelofibrosis (MF) presents an array of clinical manifestations and molecular profiles. The two distinct phenotypes- myeloproliferative and myelodepletive or cytopenic- are situated at the two poles of the disease spectrum and are largely defined by different degrees of cytopenias, splenomegaly, and distinct molecular profiles. The myeloproliferative phenotype is characterized by normal/higher peripheral blood counts or mildly decreased hemoglobin, progressive splenomegaly, and constitutional symptoms. The myeloproliferative phenotype is typically associated with secondary MF, higher JAK2 V617F burden, fewer mutations, and superior overall survival (OS). The myelodepletive phenotype is usually associated with primary MF, ≥2 cytopenias, modest splenomegaly, lower JAK2 V617F burden, higher fibrosis, greater genomic complexity, and inferior OS. Cytopenias are associated with mutations in epigenetic regulators/splicing factors, clonal evolution, disease progression, and shorter OS. Clinical variables, in conjunction with the molecular profiles, inform integrated prognostication and disease management. Ruxolitinib/fedratinib and pacritinib/momelotinib may be more suitable to treat patients with the myeloproliferative and myelodepletive phenotypes, respectively. Appreciation of MF heterogeneity and two distinct phenotypes, the different clinical manifestations and molecular profiles associated with each phenotype alongside the growing treatment expertise, the development of non-myelosuppressive JAK inhibitors, and integrated prognostication are leading to a new era in patient management. Physicians can increasingly tailor personalized treatments that will address the unique unmet needs of MF patients, including those presenting with the myelodepletive phenotype, to elicit optimal outcomes and extended OS across the disease spectrum.