Fedratinib in patients with myelofibrosis previously treated with ruxolitinib: An updated analysis of the JAKARTA2 study using stringent criteria for ruxolitinib failure

FRACTION: protocol of a phase II study of Fedratinib and Nivolumab combination in patients with myelofibrosis and resistance or suboptimal response to JAK-inhibitor treatment of the German MPN study group (GSG-MPN)

Development of Janus-kinase (JAK) inhibitors has revolutionized the therapeutic landscape for patients with myeloproliferative neoplasia (MPN). Following approval of the first JAK1/2-inhibitor Ruxolitinib, symptoms of this inflammatory disease, characterized by splenomegaly, release of inflammatory cytokines and appearance of thrombosis, could be effectively reduced for the first time. However, JAK-inhibitor treatment is limited in several aspects: 1) duration of response: 3 years after initiation of therapy more than 50% of patients have discontinued JAK-inhibitor treatment due to lack of efficacy or resistance; 2) reduction of disease burden: while effective in reducing inflammation and constitutional symptoms, JAK-inhibitors fail to reduce the malignant clone in the majority of patients and therefore lack long-term efficacy. Early clinical trials for patients with myelofibrosis (MF) have tried to address these issues for patients with suboptimal response to Ruxolitinib therapy while combination therapies with Fedratinib are rare. Recent reports provided first evidence on how the JAK2-V617F mutated myeloid cells may influence T-cell responses. JAK2-V617F promoted the synthesis of PD-L1 in MPN cells leading to limited anti-neoplastic T-cell responses, metabolic changes in T-cells and eventually JAK2-V617F-driven immune-escape of MPN cells. These findings may facilitate the use of immunotherapeutic approaches for JAK-mutated clones. Immune checkpoints refer to a variety of inhibitory pathways that are crucial for maintaining self-tolerance and modulating the duration and amplitude of physiological immune responses in peripheral tissues in order to minimize collateral tissue damage. The FRACTION study is a single arm, open label Phase II trial investigating the combination of Fedratinib with the PD-1 inhibitor Nivolumab in patients with myelofibrosis and suboptimal or lack of response to JAK-inhibitor therapy. Over a 12 months period the trial assesses longer term outcomes, particularly the effects on clinical outcomes, such as induction of clinical remissions, quality of life and improvement of anemia. No prospective clinical trial data exist for combinations of JAK- and immune-checkpoint-inhibitors in the planned MF study population and this study will provide new findings that may contribute to advancing the treatment landscape for MF patients with suboptimal responses and limited alternatives.

Advances with janus kinase inhibitors for the treatment of myeloproliferative neoplasms: an update of the literature

INTRODUCTION

The hallmark discovery of hyperactivation of the janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway was a sentinel moment in the history of myeloproliferative neoplasms (MPNs). This finding paved the way for the development of JAK inhibitors, which now represent the foundation of myelofibrosis therapy. With four JAK inhibitors now approved for myelofibrosis, awareness of their clinical efficacy and safety data and recognition of their unique pharmacologic attributes are of critical importance. Additionally, ruxolitinib represents an integral part of the therapeutic arsenal for polycythemia vera.

AREAS COVERED

This review provides a broad overview of the published literature supporting JAK inhibitor therapy for MPNs. Primarily focusing on myelofibrosis, each of the four available JAK inhibitors is reviewed in detail, including pharmacology, efficacy, and safety data. Failure of JAK inhibitors and future directions in JAK inhibitor therapy are also discussed.

EXPERT OPINION

JAK inhibitors revolutionized the treatment of MPNs and have dramatically improved patient outcomes. However, data informing selection between currently available JAK inhibitors is limited. These agents are not curative and eventually fail most patients with myelofibrosis. Combining JAK inhibitors with novel targeted agents appears to be the most promising path to further improve outcomes.

Myeloproliferative neoplasms in the adolescent and young adult population: A comprehensive review of the literature

Myeloproliferative neoplasms (MPN) are characterized by a clonal proliferation of myeloid lineage cells within the bone marrow. The classical BCR-ABL negative MPNs are comprised of polycythaemia vera, essential thrombocythaemia and primary myelofibrosis. Historically, the majority of MPNs are diagnosed in adults older than 60 years of age; however, in recent years, there has been recognition of MPNs in the adolescent and young adult (AYA) population. AYAs with MPN, typically defined as between the ages of 15 and 39 years old, may comprise up to 20% of patients diagnosed with MPN. They demonstrate unique patterns of driver mutations and thrombotic events and remain at risk for progression to more aggressive disease states. Given the likely long length of time they will live with their disease, there is a significant unmet need in identifying well-tolerated and effective treatment options for these patients, particularly with the advent of disease modification. In this review, we provide a comprehensive overview of the clinical features, disease course and management of AYA patients with MPN and, in doing so, highlight key characteristics that distinguish them from their older counterparts.

The "Heater" of "Cold" Tumors-Blocking IL-6

The resolution of inflammation is not simply the end of the inflammatory response but rather a complex process that involves various cells, inflammatory factors, and specialized proresolving mediators following the occurrence of inflammation. Once inflammation cannot be cleared by the body, malignant tumors may be induced. Among them, IL-6, as an immunosuppressive factor, activates a variety of signal transduction pathways and induces tumorigenesis. Monitoring IL-6 can be used for the diagnosis, efficacy evaluation and prognosis of tumor patients. In terms of treatment, improving the efficacy of targeted and immunotherapy remains a major challenge. Blocking IL-6 and its mediated signaling pathways can regulate the tumor immune microenvironment and enhance immunotherapy responses by activating immune cells. Even transform "cold" tumors that are difficult to respond to immunotherapy into immunogenic "hot" tumors, acting as a "heater" for "cold" tumors, restarting the tumor immune cycle, and reducing immunotherapy-related toxic reactions and drug resistance. In clinical practice, the combined application of IL-6 inhibition with targeted therapy and immunotherapy may produce synergistic results. Nevertheless, additional clinical trials are imperative to further validate the safety and efficacy of this therapeutic approach.

Safety and efficacy of fedratinib in patients with myelofibrosis previously treated with ruxolitinib: primary analysis of FREEDOM trial

The phase 3b FREEDOM trial (ClinicalTrials.gov: NCT03755518) evaluates efficacy/safety of fedratinib in intermediate- or high-risk myelofibrosis patients with platelet count ≥50 × 109/L, previously treated with ruxolitinib. The trial design included protocol specified strategies to mitigate the risk for gastrointestinal (GI) adverse events (AEs), thiamine supplementation, and encephalopathy surveillance. Due to COVID-19, accrual was cut short with 38 patients enrolled. In the efficacy evaluable population (n = 35), nine (25.7%; 95% confidence interval 12.5-43.3) patients achieved primary endpoint of ≥35% spleen volume reduction (SVR) at end of cycle (EOC) 6; and 22 (62.9%) patients showed best overall response of ≥35% SVR up to end of treatment. Sixteen (44.4%) patients showed ≥50% reduction in total symptom score at EOC6 (n = 36). Compared to previously reported JAKARTA-2 trial, rates of GI AEs were lower, and no patient developed encephalopathy. Overall, FREEDOM study showed clinically relevant spleen and symptom responses with fedratinib, and effective mitigation of GI AEs.

Recent advances in JAK2 inhibition for the treatment of myelofibrosis

INTRODUCTION

Myelofibrosis (MF) is a BCR-ABL-negative myeloproliferative neoplasm characterized by splenomegaly, constitutional symptoms, cytopenias, a potential for leukemic transformation, and increased mortality. Patients who are ineligible for stem cell transplant rely on pharmacologic therapies of noncurative intent, whose cornerstone consists of JAK inhibitors (JAKi). While current JAKi are efficacious in controlling symptoms and splenic volume, none meaningfully reduce clonal burden nor halt disease progression, and patients oftentimes develop JAKi intolerant, relapsed, or refractory MF. As such, there remains an urgent necessity for second-line options and novel therapies with disease-modifying properties.

AREAS COVERED

In this review, we delineate the mechanistic rationale, along with the latest safety and efficacy data, of investigational JAKi-based MF treatment strategies, with a focus on JAKi monotherapies and combinations of novel agents with approved JAKi. Our literature search consisted of extensive review of PubMed and clinicaltrials.gov.

EXPERT OPINION

A myriad of promising MF-directed therapies are in late-phase studies. Following their approval, treatment selection should be tailored to patient-specific treatment goals and disease characteristics, with an emphasis on combination therapies of JAKi with novel agents of differing mechanistic targets that possess anti-clonal properties, in attempt to alter disease course and concurrently limit dose-dependent JAKi toxicities.

Incidence of blast phase in myelofibrosis patients according to anemia severity at ruxolitinib start and during therapy

BACKGROUND

Anemia is frequently present in patients with myelofibrosis (MF), and it may be exacerbated by treatment with the JAK2-inhibitor ruxolitinib (RUX). Recently, a relevant blast phase (BP) incidence has been reported in anemic MF patients unexposed to RUX.

METHODS

The authors investigated the incidence of BP in 886 RUX-treated MF patients, included in the "RUX-MF" retrospective study.

RESULTS

The BP incidence rate ratio (IRR) was 3.74 per 100 patient-years (3.74 %p-y). At therapy start, Common Terminology Criteria for Adverse Events grade 3-4 anemia (hemoglobin [Hb] <8 g/dL) and severe sex/severity-adjusted anemia (Hb <8/<9 g/dL in women/men) were present in 22.5% and 25% patients, respectively. IRR of BP was 2.34 in patients with no baseline anemia and reached respectively 4.22, 4.89, and 4.93 %p-y in patients with grade 1, 2, and 3-4 anemia. Considering the sex/severity-adjusted Hb thresholds, IRR of BP was 2.85, 4.97, and 4.89 %p-y in patients with mild/no anemia, moderate, and severe anemia. Transfusion-dependent patients had the highest IRR (5.03 %p-y). Progression-free survival at 5 years was 70%, 52%, 43%, and 27% in patients with no, grade 1, 2, and 3-4 anemia, respectively (p < .001). At 6 months, 260 of 289 patients with no baseline anemia were receiving ruxolitinib, and 9.2% had developed a grade 3-4 anemia. By 6-month landmark analysis, BP-free survival was significantly worse in patients acquiring grade 3-4 anemia (69.3% vs. 88.1% at 5 years, p < .001).

CONCLUSIONS

This study highlights that anemia correlates with an increased risk of evolution into BP, both when present at baseline and when acquired during RUX monotherapy. Innovative anemia therapies and disease-modifying agents are warranted in these patients.

Real-World Electronic Medical Records Data Identify Risk Factors for Myelofibrosis and Can Be Used to Validate Established Prognostic Scores

Myelofibrosis (MF) is a myeloproliferative neoplasia arising de novo as primary myelofibrosis (PMF) or secondary to polycythemia vera or essential thrombocythemia. Patients experience a high symptom burden and a marked reduction in life expectancy. Despite progress in molecular understanding and treatment, the clinical and prognostic heterogeneity of MF complicates treatment decisions. The International Prognostic Scoring System (IPSS) integrates clinical factors for risk stratification in MF. This study leverages the TriNetX database with more than 64,000 MF patients to assess the impact of accessible parameters on survival and complicating events, including AML transformation, cachexia, increased systemic inflammation, thrombosis and hemorrhage. Age over 65 years correlated with increased risks of death, AML transformation, thrombosis and hemorrhage. Anemia (Hb < 10 g/dL), leukocytosis (>25 × 103/µL) and thrombocytopenia (<150 × 103/µL) reduced survival and increased risks across all assessed events. Monocytosis is associated with decreased survival, whereas eosinophilia and basophilia were linked to improved survival. Further, as proof of concept for the applicability of TriNetX for clinical scores, we devised a simplified IPSS, and confirmed its value in predicting outcomes. This comprehensive study underscores the importance of age, anemia, leukocytosis and thrombocytopenia in predicting disease trajectory and contributes to refining prognostic models, addressing the challenges posed by the disease's heterogeneity.

Relative bioavailability of fedratinib through various alternative oral administration methods in healthy adults

Fedratinib is an oral Janus kinase 2-selective inhibitor for the treatment of adult patients with intermediate-2 or high-risk myelofibrosis; however, some patients have difficulty with oral dosing. This randomized, phase 1, open-label, 2-part crossover study evaluated the relative bioavailability, safety, tolerability, taste, and palatability of fedratinib resulting from various alternative oral administration methods in healthy adults. Participants could receive fedratinib 400 mg orally as intact capsules along with a nutritional supplement; as contents of capsules dispersed in a nutritional supplement, delivered via nasogastric tube; or as a divided dose of 200 mg orally twice daily as intact capsules with a nutritional supplement. Fifty-eight participants received treatment. Total exposure to fedratinib was similar after oral administration of intact capsules or when dispersed in a nutritional supplement (area under the plasma concentration-time curve from time 0 to the time of the last quantifiable concentration geometric mean ratio [AUC0-t GMR] [90% CI], 1.007 [0.929-1.092]). Total exposure to fedratinib was slightly reduced following nasogastric administration (AUC0-t GMR 0.850 [0.802-0.901]) and as a divided dose (AUC0-t GMR 0.836 [0.789-0.886]). No new safety signals were identified for fedratinib, and most participants found the taste and palatability acceptable when dispersed in a nutritional supplement. Overall, results suggest no clinically meaningful differences in total exposure to fedratinib between the tested oral administration methods. These findings may facilitate administration of fedratinib to patients who are intolerant of swallowing the capsule dosage form. (ClinicalTrials.gov: NCT05051553).

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.

Real-World Use of Fedratinib for Myelofibrosis Following Prior Ruxolitinib Failure: Patient Characteristics, Treatment Patterns, and Clinical Outcomes

BACKGROUND

There is a lack of established clinical outcomes for patients with myelofibrosis (MF) receiving fedratinib following ruxolitinib failure. This study examined real-world patient characteristics, treatment patterns, and clinical outcomes of patients with MF treated with fedratinib following ruxolitinib failure in US clinical practice.

PATIENTS AND METHODS

This retrospective patient chart review included adults with a physician-reported diagnosis of MF, who initiated fedratinib after discontinuing ruxolitinib. Descriptive analyses characterized patient characteristics, clinical outcomes, and treatment patterns from MF diagnosis through ruxolitinib and fedratinib treatment.

RESULTS

Twenty-four physicians abstracted data for 150 eligible patients. Approximately 55.3% of the patients were male, 68.0% were White, and median age at MF diagnosis was 68 (range, 35-84) years. Median duration of ruxolitinib therapy was 7.6 (range, 0.7-65.5) months. At initiation of fedratinib, 88.0% of patients had palpable spleen and a mean spleen size of 16.0 (standard deviation [SD], 5.9) cm. Spleen size decreased by 19.4% to 13.2 (SD, 7.9) cm at month 3 (P = .0001) and by 53.4% to 7.2 (SD, 7.4) cm at month 6 (P = .01) of fedratinib treatment, respectively. Almost one-third (26.8%) of patients had achieved ≥ 50% spleen reduction by month 6. Mean number of symptoms also decreased significantly at month 3 (P < .0001) and month 6 (P = .01).

CONCLUSION

Fedratinib appears to deliver spleen and symptom benefits in real-world patients with MF previously treated with ruxolitinib.

Evolving landscape of JAK inhibition in myelofibrosis: monotherapy and combinations

Myeloproliferative neoplasms (MPNs) are characterized by clonal myeloproliferation in 1 or more of the hematopoietic stem cell lineages. Primary myelofibrosis (MF), post-polycythemia vera MF, and post-essential thrombocythemia MF have the worst prognosis and are characterized by the presence of cytokine-mediated symptom complex, splenomegaly, progressive marrow failure, and clonal instability, leading to leukemic transformation. The key therapeutic aims encompass the management of symptoms, splenomegaly, and anemia and the improvement of survivals. These therapeutic aims have evolved with the availability of Jak inhibitors and novel agents, making disease modification potentially achievable. Novel agents may potentially target MPN stem cells, epigenetic alterations, signaling pathways, and apoptotic pathways. In this case-based review, we outline our approach to the management of MF and discuss the therapeutic landscape of MF, highlighting the utility of Jak inhibitors and novel Jak inhibitor-based combinations.

Management of classical Philadelphia chromosome-negative myeloproliferative neoplasms in Asia: consensus of the Asian Myeloid Working Group

Myeloproliferative neoplasms (MPN) are a heterogeneous group of clonal hematopoietic stem cell disorders characterized clinically by the proliferation of one or more hematopoietic lineage(s). The classical Philadelphia-chromosome (Ph)-negative MPNs include polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). The Asian Myeloid Working Group (AMWG) comprises representatives from fifteen Asian centers experienced in the management of MPN. This consensus from the AMWG aims to review the current evidence in the risk stratification and treatment of Ph-negative MPN, to identify management gaps for future improvement, and to offer pragmatic approaches for treatment commensurate with different levels of resources, drug availabilities and reimbursement policies in its constituent regions. The management of MPN should be patient-specific and based on accurate diagnostic and prognostic tools. In patients with PV, ET and early/prefibrotic PMF, symptoms and risk stratification will guide the need for early cytoreduction. In younger patients requiring cytoreduction and in those experiencing resistance or intolerance to hydroxyurea, recombinant interferon-α preparations (pegylated interferon-α 2A or ropeginterferon-α 2b) should be considered. In myelofibrosis, continuous risk assessment and symptom burden assessment are essential in guiding treatment selection. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) in MF should always be based on accurate risk stratification for disease-risk and post-HSCT outcome. Management of classical Ph-negative MPN entails accurate diagnosis, cytogenetic and molecular evaluation, risk stratification, and treatment strategies that are outcome-oriented (curative, disease modification, improvement of quality-of-life).

Real-world outcomes with fedratinib therapy in patients who discontinued ruxolitinib for primary myelofibrosis

Aim: Fedratinib is an oral selective JAK2 inhibitor approved in the USA for the treatment of adult patients with intermediate-2 or high-risk primary or secondary myelofibrosis (MF). Methods: This observational study assessed adult US patients who received ruxolitinib for primary MF (Flatiron Health database: 1 January 2011-31 October 2020). Patients were stratified by post-ruxolitinib treatment (fedratinib vs non-fedratinib). Results: Characteristics were comparable between fedratinib (n=70) and non-fedratinib (n=159) groups (median age: 71.0 vs 70.0 years; females: 55.7 vs 50.3%; median follow-up: 7.0 vs 6.0 months). Median overall survival (not reached vs 17 months) and 12 month survival (71.6 vs 53.5%) were improved with fedratinib versus the non-fedratinib therapies. Conclusion: In MF patients who received frontline ruxolitinib, survival was improved with subsequent fedratinib versus non-fedratinib care.

New era for myelofibrosis treatment with novel agents beyond Janus kinase-inhibitor monotherapy: Focus on clinical development of BCL-XL /BCL-2 inhibition with navitoclax

Myelofibrosis is a heterogeneous myeloproliferative neoplasm characterized by chronic inflammation, progressive bone marrow failure, and hepatosplenic extramedullary hematopoiesis. Treatments like Janus kinase inhibitor monotherapy (e.g., ruxolitinib) provide significant spleen and symptom relief but demonstrate limited ability to lead to a durable disease modification. There is an urgent unmet medical need for treatments with a novel mechanism of action that can modify the underlying pathophysiology and affect the disease course of myelofibrosis. This review highlights the role of B-cell lymphoma (BCL) protein BCL-extra large (BCL-XL ) in disease pathogenesis and the potential role that navitoclax, a BCL-extra large/BCL-2 inhibitor, may have in myelofibrosis treatment.

Current therapies for classic myeloproliferative neoplasms: A focus on pathophysiology and supportive care

PURPOSE

This article concisely evaluates current therapies that have received regulatory approval for the treatment of classic myeloproliferative neoplasms (MPNs). Pertinent pathophysiology and supportive care are discussed. Emerging therapies are also briefly described.

SUMMARY

MPNs are a heterogeneous group of diseases characterized by acquired abnormalities of hematopoietic stem cells (HSCs), resulting in the generation of transformed myeloid progenitor cells that overproduce mature and immature cells within the myeloid lineage. Mutations in JAK2 and other driver oncogenes are central to the genetic variability of these diseases. Cytoreductive therapies such as hydroxyurea, anagrelide, interferon, and therapeutic phlebotomy aim to lower the risk of thrombotic events without exposing patients to an increased risk of leukemic transformation. However, no comparisons can be made between these therapies, as reduction of thrombotic risk has not been used as an endpoint. On the other hand, Janus kinase (JAK) inhibitors such as ruxolitinib, fedratinib, pacritinib, and momelotinib (an investigational agent at the time of writing) directly target the constitutively activated JAK-signal transducer and activator of transcription (JAK-STAT) pathway of HSCs in the bone marrow. Mutations of genes in the JAK-STAT signaling pathway provide a unifying understanding of MPNs, spur therapeutic innovations, and represent opportunities for pharmacists to optimize mitigation strategies for both disease-related and treatment-related adverse effects.

CONCLUSION

Treatment options for MPNs span a wide range of disease mechanisms. The growth of targeted therapies holds promise for expanding the treatment arsenal for these rare, yet complex diseases and creates opportunities to optimize supportive care for affected patients.

Momelotinib (JAK1/JAK2/ACVR1 inhibitor): mechanism of action, clinical trial reports, and therapeutic prospects beyond myelofibrosis

Janus kinase (JAK) 2 inhibitors are now part of the therapeutic armamentarium for primary and secondary myelofibrosis (MF). Patients with MF endure shortened survival and poor quality of life. Allogeneic stem cell transplantation (ASCT) is currently the only treatment modality in MF with the potential to cure the disease or prolong survival. By contrast, current drug therapy in MF targets quality of life and does not modify the natural history of the disease. The discovery of JAK2 and other JAK-STAT activating mutations (i.e., CALR and MPL) in myeloproliferative neoplasms, including MF, has facilitated the development of several JAK inhibitors that are not necessarily specific to the oncogenic mutations themselves but have proven effective in countering JAK-STAT signaling, resulting in suppression of inflammatory cytokines and myeloproliferation. This non-specific activity resulted in clinically favorable effects on constitutional symptoms and splenomegaly and, consequently, approval by the Food and Drug Administration (FDA) of three small molecule JAK inhibitors: ruxolitinib, fedratinib, and pacritinib. A fourth JAK inhibitor, momelotinib, is poised for FDA approval soon and has been shown to provide additional benefit in alleviating transfusion-dependent anemia in MF. The salutary effect of momelotinib on anemia has been attributed to inhibition of activin A receptor, type 1 (ACVR1) and recent information suggests a similar effect from pacritinib. ACRV1 mediates SMAD2/3 signaling which contributes to upregulation of hepcidin production and iron-restricted erythropoiesis. Targeting ACRV1 raises therapeutic prospects in other myeloid neoplasms associated with ineffective erythropoiesis, such as myelodysplastic syndromes with ring sideroblasts or SF3B1 mutation, especially those with co-expression of a JAK2 mutation and thrombocytosis.

A Prognostic Model to Predict Ruxolitinib Discontinuation and Death in Patients with Myelofibrosis

Most patients with myelofibrosis (MF) discontinue ruxolitinib (JAK1/JAK2 inhibitor) in the first 5 years of therapy due to therapy failure. As the therapeutic possibilities of MF are expanding, it is critical to identify patients predisposed to early ruxolitinib monotherapy failure and worse outcomes. We investigated predictors of early ruxolitinib discontinuation and death on therapy in 889 patients included in the "RUX-MF" retrospective study. Overall, 172 patients were alive on ruxolitinib after ≥5 years (long-term ruxolitinib, LTR), 115 patients were alive but off ruxolitinib after ≥5 yrs (short-term RUX, STR), and 123 patients died while on ruxolitinib after <5 yrs (early death on ruxolitinib, EDR). The cumulative incidence of the blast phase was similar in LTR and STR patients (p = 0.08). Overall survival (OS) was significantly longer in LTR pts (p = 0.002). In multivariate analysis, PLT < 100 × 109/L, Hb < 10 g/dL, primary MF, absence of spleen response at 3 months and ruxolitinib starting dose <10 mg BID were associated with higher probability of STR. Assigning one point to each significant variable, a prognostic model for STR (STR-PM) was built, and three groups were identified: low (score 0-1), intermediate (score 2), and high risk (score ≥ 3). The STR-PM may identify patients at higher risk of failure with ruxolitinib monotherapy who should be considered for alternative frontline strategies.

Pacritinib is a potent ACVR1 inhibitor with significant anemia benefit in patients with myelofibrosis

In patients with cytopenic myelofibrosis, treatment with the JAK2/IRAK1 inhibitor pacritinib was associated with anemia benefit in the phase 3 PERSIST-2 study. The impact of pacritinib on transfusion independence (TI) has not been previously described, nor has the mechanism by which pacritinib improves anemia been elucidated. Because it has been previously postulated that inhibition of activin A receptor, type 1 (ACVR1)/activin receptor-like kinase-2 improves anemia in patients with myelofibrosis via suppression of hepcidin production, we assessed the relative inhibitory potency of pacritinib compared with other JAK2 inhibitors against ACVR1. Pacritinib inhibited ACVR1 with greater potency (half-maximal inhibitory concentration [IC50] = 16.7 nM; Cmax:IC50 = 12.7) than momelotinib (IC50 = 52.5 nM; Cmax:IC50 = 3.2), fedratinib (IC50 = 273 nM; Cmax:IC50 = 1.0), or ruxolitinib (IC50 > 1000; Cmax:IC50 < 0.01). Pacritinib's inhibitory activity against ACVR1 was corroborated via inhibition of downstream SMAD signaling in conjunction with marked suppression of hepcidin production. Among patients on PERSIST-2 who were not transfusion independent at baseline based on Gale criteria, a significantly greater proportion achieved TI on pacritinib compared with those treated on best available therapy (37% vs 7%, P = .001), and significantly more had a ≥50% reduction in transfusion burden (49% vs 9%, P < .0001). These data indicate that the anemia benefit of the JAK2/IRAK1 inhibitor pacritinib may be a function of potent ACVR1 inhibition.

Safety and efficacy of jaktinib (a novel JAK inhibitor) in patients with myelofibrosis who are relapsed or refractory to ruxolitinib: A single-arm, open-label, phase 2, multicenter study

Ruxolitinib has demonstrated efficacy in patients with myelofibrosis (MF). However, substantial number of patients may not respond after 3-6 months of treatment or develop resistance over time. In this phase 2 trial, patients with a current diagnosis of intermediate or high-risk MF who either had an inadequate splenic response or spleen regrowth after ruxolitinib treatment were enrolled. All patients received jaktinib 100 mg Bid. The primary endpoint was the proportion of patients with ≥35% reduction in spleen volume (SVR 35) at week 24. The secondary endpoints included change of MF-related symptoms, anemic response, and safety profile. From July 6, 2021, to January 24, 2022, 34 ruxolitinib-refractory or relapsed patients were enrolled, 52.9% (18 of 34) were DIPSS intermediate 2 or high risk. SVR 35 at week 24 was 32.4% (11 of 34, 95% CI 19.1%-49.2%) in all patients and 33.3% (6 of 18, 95% CI 16.3%-56.3%) in the intermediate 2 or high-risk group. A total of 50% (8 of 16) transfusion-independent patients with hemoglobin (HGB) <100 g/L at baseline had HGB elevation ≥20 g/L within 24 weeks. Furthermore, 46.4% (13 of 28) of patients had a ≥ 50% decrease in the total symptom score (TSS 50) at week 24. The most common grade ≥3 treatment-emergent adverse events (TEAEs) were thrombocytopenia (32.4%), anemia (32.4%), and leukocytosis (20.6%). In total, 13 (38.2%) of 34 patients had serious adverse events (SAE), of which drug-related SAEs were found in 5 patients (14.7%). These results indicate that jaktinib can be a promising treatment option for patients with MF who have either become refractory to or relapsed after ruxolitinib treatment.

Safety and efficacy of jaktinib (a novel JAK inhibitor) in patients with myelofibrosis who are intolerant to ruxolitinib: A single-arm, open-label, phase 2, multicenter study

Although ruxolitinib improves splenomegaly and constitutional symptoms in patients with myelofibrosis (MF), a substantial proportion of patients discontinue ruxolitinib because of intolerance. This phase 2 trial investigated the safety and efficacy of jaktinib, a novel JAK inhibitor in patients with ruxolitinib-intolerant MF. The primary endpoint was the proportion of patients with ≥35% reduction in spleen volume (SVR35) at week 24. The secondary endpoints included change of MF-related symptoms, anemic response, and safety profiles. Between December 18, 2019, and November 24, 2021, 51 patients were enrolled, 45 treated with jaktinib 100 mg bid (100 mg bid group) and six received non-100 mg bid doses (non-100 mg bid group). The SVR35 at week 24 in the 100 mg bid group was 43.2% (19/44, 95% CI 29.7%-57.8%). There were 41.9% (13/31) of transfusion-independent patients with hemoglobin (HGB) ≤100 g/L who had HGB elevation ≥20 g/L within 24 weeks. The proportion of patients with a ≥50% decrease in the total symptom score (TSS 50) at week 24 was 61.8% (21/34). The most commonly reported grade ≥3 treatment-emergent adverse events (TEAEs) in the 100 mg bid group were anemia 31.1%, thrombocytopenia 22.2%, and infectious pneumonia 17.8%. A total of 16 (35.6%) in the 100 mg bid group had serious adverse events, and 4 (8.9%) were considered possibly drug related. These results indicate jaktinib can provide a treatment option for patients with MF who are intolerant to ruxolitinib.

Recent progress of JAK inhibitors for hematological disorders

JAK inhibitors are important therapeutic options for hematological disorders, especially myeloproliferative neoplasms. Ruxolitinib, the first JAK inhibitor approved for clinical use, improves splenomegaly and ameliorates constitutional symptoms in both myelofibrosis and polycythemia vera patients. Ruxolitinib is also useful for controlling hematocrit levels in polycythemia vera patients who were inadequately controlled by conventional therapies. Furthermore, pretransplantation use of ruxolitinib may improve the outcome of allo-hematopoietic stem cell transplantation in myelofibrosis. In contrast to these clinical merits, evidence of the disease-modifying action of ruxolitinib, i.e., reduction of malignant clones or improvement of bone marrow pathological findings, is limited, and many myelofibrosis patients discontinued ruxolitinib due to adverse events or disease progression. To overcome these limitations of ruxolitinib, several new types of JAK inhibitors have been developed. Among them, fedratinib was proven to provide clinical merits even in patients who were resistant or intolerant to ruxolitinib. Pacritinib and momelotinib have shown merits for myelofibrosis patients with thrombocytopenia or anemia, respectively. In addition to treatment for myeloproliferative neoplasms, recent studies have demonstrated that JAK inhibitors are novel and attractive therapeutic options for corticosteroid-refractory acute as well as chronic graft versus host disease.

Emerging Treatment Options for Myelofibrosis: Focus on Anemia

Myelofibrosis (MF) is a hematologic malignancy characterized by abnormal proliferation of myeloid cells and the release of pro-inflammatory cytokines, leading to progressive bone marrow dysfunction. The introduction of ruxolitinib just over a decade ago marked a significant advancement in MF therapy, with JAK inhibitors now being the first-line treatment for reducing spleen size and managing symptoms. However, early JAK inhibitors (ruxolitinib and fedratinib) are often associated with cytopenias, particularly thrombocytopenia and anemia, which limit their tolerability. To address these complications, pacritinib has been developed and recently approved for patients with thrombocytopenia, while momelotinib is in development for those with anemia. Although JAK inhibitors have significantly improved the quality of life of MF patients, they have not demonstrated the ability to reduce leukemic transformation and their impact on survival is debated. Numerous drugs are currently being developed and investigated in clinical trials, both as standalone therapy and in combination with JAK inhibitors, with promising results enhancing the benefits of JAK inhibitors. In the near future, MF treatment strategies will involve selecting the most suitable JAK inhibitor based on individual patient characteristics and prior therapy. Ongoing and future clinical trials are crucial for advancing the field and expanding therapeutic options for MF patients.

Evolving cognition of the JAK-STAT signaling pathway: autoimmune disorders and cancer

The Janus kinase (JAK) signal transducer and activator of transcription (JAK-STAT) pathway is an evolutionarily conserved mechanism of transmembrane signal transduction that enables cells to communicate with the exterior environment. Various cytokines, interferons, growth factors, and other specific molecules activate JAK-STAT signaling to drive a series of physiological and pathological processes, including proliferation, metabolism, immune response, inflammation, and malignancy. Dysregulated JAK-STAT signaling and related genetic mutations are strongly associated with immune activation and cancer progression. Insights into the structures and functions of the JAK-STAT pathway have led to the development and approval of diverse drugs for the clinical treatment of diseases. Currently, drugs have been developed to mainly target the JAK-STAT pathway and are commonly divided into three subtypes: cytokine or receptor antibodies, JAK inhibitors, and STAT inhibitors. And novel agents also continue to be developed and tested in preclinical and clinical studies. The effectiveness and safety of each kind of drug also warrant further scientific trials before put into being clinical applications. Here, we review the current understanding of the fundamental composition and function of the JAK-STAT signaling pathway. We also discuss advancements in the understanding of JAK-STAT-related pathogenic mechanisms; targeted JAK-STAT therapies for various diseases, especially immune disorders, and cancers; newly developed JAK inhibitors; and current challenges and directions in the field.

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

Ruxolitinib has been the cornerstone of pharmacologic therapy for myelofibrosis for over a decade. However, the last several years have witnessed the regulatory approval of other Janus kinase (JAK) inhibitors for myelofibrosis, i.e. fedratinib, pacritinib, and US approval of momelotinib is widely anticipated in 2023. Due to the multifaceted clinical presentation of myelofibrosis, a watertight definition of ruxolitinib failure has remained elusive, as "progression" on ruxolitinib can take many forms and management is highly nuanced. Yet, the availability of other JAK inhibitors and potential future availability of non-JAK inhibitor agents for myelofibrosis make a consensus on management of ruxolitinib failure critically important. This consensus paper summarizes a discussion between multiple academic and community physician experts, a pharmacist and an advanced practice provider around the issues to be considered for the optimal care of patients with myelofibrosis whose disease is refractory to or does not respond adequately to ruxolitinib, or who exhibit intolerance to ruxolitinib. The panel identified several areas of consensus, as well as some areas where more data to inform evidence-based practice are needed. In some situations, maintaining ruxolitinib while adding another agent, e.g. to address anemia, is appropriate, whereas in others, switching to a different drug has merit.

Defining ruxolitinib failure and transition to next-line therapy for patients with myelofibrosis: a modified Delphi panel consensus study

Aim: To define ruxolitinib failure and develop parameters to guide transition to next-line therapy for patients with myelofibrosis. Methods: A modified Delphi panel with 14 hematologists-oncologists. Survey concepts included defining primary refractory status, loss of response, disease progression, intolerance and transition to next-line therapy. Results: Ruxolitinib failure may be defined as no improvement in symptoms or spleen size, progressive disease or ruxolitinib intolerance, following a maximally tolerated dose for ≥3 months. Loss of spleen response 1 month after initial response may prompt discontinuation. Lack of evidence to inform transition to next-line therapy was noted; tapering ruxolitinib should be considered according to ruxolitinib dose and patient characteristics. Conclusion: Expert consensus was provided on defining ruxolitinib failure and transition to next-line therapy as summarized in this position paper, which may support considerations in the development of future clinical practice guidelines.

A chatbot for mental health support: exploring the impact of Emohaa on reducing mental distress in China

Introduction

The growing demand for mental health support has highlighted the importance of conversational agents as human supporters worldwide and in China. These agents could increase availability and reduce the relative costs of mental health support. The provided support can be divided into two main types: cognitive and emotional. Existing work on this topic mainly focuses on constructing agents that adopt Cognitive Behavioral Therapy (CBT) principles. Such agents operate based on pre-defined templates and exercises to provide cognitive support. However, research on emotional support using such agents is limited. In addition, most of the constructed agents operate in English, highlighting the importance of conducting such studies in China. To this end, we introduce Emohaa, a conversational agent that provides cognitive support through CBT-Bot exercises and guided conversations. It also emotionally supports users through ES-Bot, enabling them to vent their emotional problems. In this study, we analyze the effectiveness of Emohaa in reducing symptoms of mental distress.

Methods and Results

Following the RCT design, the current study randomly assigned participants into three groups: Emohaa (CBT-Bot), Emohaa (Full), and control. With both Intention-To-Treat (N=247) and PerProtocol (N=134) analyses, the results demonstrated that compared to the control group, participants who used two types of Emohaa experienced considerably more significant improvements in symptoms of mental distress, including depression (F[2,244]=6.26, p=0.002), negative affect (F[2,244]=6.09, p=0.003), and insomnia (F[2,244]=3.69, p=0.026).

Discussion

Based on the obtained results and participants' satisfaction with the platform, we concluded that Emohaa is a practical and effective tool for reducing mental distress.

Ten years after ruxolitinib approval for myelofibrosis: a review of clinical efficacy

Myelofibrosis (MF) is a chronic myeloproliferative neoplasm characterized by splenomegaly, abnormal cytokine expression, cytopenias, and progressive bone marrow fibrosis. The disease often manifests with burdensome symptoms and is associated with reduced survival. Ruxolitinib, an oral Janus kinase (JAK) 1 and JAK2 inhibitor, was the first agent approved for MF. As a first-in-class targeted treatment, ruxolitinib approval transformed the MF treatment approach and remains standard of care. In addition, targeted inhibition of JAK1/JAK2 signaling, a key molecular pathway underlying MF pathogenesis, and the large volume of literature evaluating ruxolitinib, have led to a better understanding of the disease and improved management in general. Here we review ruxolitinib efficacy in patients with MF in the 10 years following approval, including demonstration of clinical benefit in the phase 3 COMFORT-I/II trials, real-world evidence, translational studies, and expanded access data. Lastly, future directions for MF treatment are discussed, including ruxolitinib-based combination therapies.

Myelofibrosis

The clinical phenotype of primary and post-polycythemia vera and postessential thrombocythemia myelofibrosis (MF) is dominated by splenomegaly, symptomatology, a variety of blood cell alterations, and a tendency to develop vascular complications and blast phase. Diagnosis requires assessing complete cell blood counts, bone marrow morphology, deep genetic evaluations, and disease history. Driver molecular events consist of JAK2V617F, CALR, and MPL mutations, whereas about 8% to 10% of MF are "triple-negative." Additional myeloid-gene variants are described in roughly 80% of patients. Currently available clinical-based and integrated clinical/molecular-based scoring systems predict the survival of patients with MF and are applied for conventional treatment decision-making, indication to stem cell transplant (SCT) and allocation in clinical trials. Standard treatment consists of anemia-oriented therapies, hydroxyurea, and JAK inhibitors such as ruxolitinib, fedratinib, and pacritinib. Overall, spleen volume reduction of 35% or greater at week 24 can be achieved by 42% of ruxolitinib-, 47% of fedratinib-, 19% of pacritinib-, and 27% of momelotinib-treated patients. Now, it is time to move towards new paradigms for evaluating efficacy like disease modification, that we intend as a robust and unequivocal effect on disease biology and/or on patient survival. The growing number of clinical trials potentially pave the way for new strategies in patients with MF. Translational studies of some molecules showed an early effect on bone marrow fibrosis and on variant allele frequencies of myeloid genes. SCT is still the only curative option, however, it is associated with relevant challenges. This review focuses on the diagnosis, prognostication, and treatment of MF.

MEK Inhibition Synergizes with TYK2 Inhibitors in NF1-Associated Malignant Peripheral Nerve Sheath Tumors

PURPOSE

Malignant peripheral nerve sheath tumors (MPNST) are aggressive sarcomas with limited treatment options and poor survival rates. About half of MPNST cases are associated with the neurofibromatosis type 1 (NF1) cancer predisposition syndrome. Overexpression of TYK2 occurs in the majority of MPNST, implicating TYK2 as a therapeutic target.

EXPERIMENTAL DESIGN

The effects of pharmacologic TYK2 inhibition on MPNST cell proliferation and survival were examined using IncuCyte live cell assays in vitro, and downstream actions were analyzed using RNA-sequencing (RNA-seq), qPCR arrays, and validation of protein changes with the WES automated Western system. Inhibition of TYK2 alone and in combination with MEK inhibition was evaluated in vivo using both murine and human MPNST cell lines, as well as MPNST PDX.

RESULTS

Pharmacologic inhibition of TYK2 dose-dependently decreased proliferation and induced apoptosis over time. RNA-seq pathway analysis on TYK2 inhibitor-treated MPNST demonstrated decreased expression of cell cycle, mitotic, and glycolysis pathways. TYK2 inhibition resulted in upregulation of the MEK/ERK pathway gene expression, by both RNA-seq and qPCR array, as well as increased pERK1/2 levels by the WES Western system. The compensatory response was tested with dual treatment with TYK2 and MEK inhibitors, which synergistically decreased proliferation and increased apoptosis in vitro. Finally, combination therapy was shown to inhibit growth of MPNST in multiple in vivo models.

CONCLUSIONS

These data provide the preclinical rationale for the development of a phase I clinical trial of deucravacitinib and mirdametinib in NF1-assosciated MPNST.

An evaluation of fedratinib for adult patients with newly diagnosed and previously treated myelofibrosis

INTRODUCTION

Myelofibrosis (MF) is a life-shortening myeloproliferative neoplasm that has multiple features such as clonal proliferation, fibrosis and splenomegaly. Until recently, ruxolitinib, a Janus Kinase (JAK) 1/2 inhibitor was the only targeted therapy approved for transplant-ineligible patients with MF and who require treatment for symptoms and/or splenomegaly. However, the discontinuation rate with ruxolitinib at 3 to 5 years is high and mostly due to loss of response or toxicity, and these patients had no subsequent treatment.

AREAS COVERED

Fedratinib, a selective JAK2 inhibitor, was approved by the Food and Drug Administration (FDA) in August 2019 for the treatment of intermediate-2 or high-risk primary or secondary MF, regardless of prior JAK inhibitor treatment for the management of symptoms and splenomegaly. We discuss herein the development of fedratinib and its pharmacology and pharmacokinetics as well as the clinical development and the future directions. We used PubMed for the search of articles related to fedratinib and myelofibrosis.

EXPERT OPINION

Fedratinib provided a second-line treatment for patients with MF who failed or discontinued ruxolitinib. New combinations of JAK inhibitors with other targeted therapies are a must in order to improve the management of MF.

SOHO State of the Art Updates and Next Questions: Novel Therapeutic Strategies in Development for Myelofibrosis

Development of myelofibrosis (MF) therapeutics has reached fruition as the transformative impact of JAK2 inhibitors in the MPN landscape is complemented/expanded by a profusion of novel monotherapies and rational combinations in the frontline and second line settings. Agents in advanced clinical development span various mechanisms of action (eg, epigenetic or apoptotic regulation), may address urgent unmet clinical needs (cytopenias), increase the depth/duration of spleen and symptom responses elicited by ruxolitinib, improve other aspects of the disease besides splenomegaly/constitutional symptoms (eg, resistance to ruxolitinib, bone marrow fibrosis or disease course), provide personalized strategies, and extend overall survival (OS). Ruxolitinib had a dramatic impact on the quality of life and OS of MF patients. Recently, pacritinib received regulatory approval for severely thrombocytopenic MF patients. Momelotinib is advantageously poised among JAK inhibitors given its differentiated mode of action (suppression of hepcidin expression). Momelotinib demonstrated significant improvements in anemia measures, spleen responses, and MF-associated symptoms in MF patients with anemia; and will likely receive regulatory approval in 2023. An array of other novel agents combined with ruxolitinib, such as pelabresib, navitoclax, parsaclisib, or as monotherapies (navtemadlin) are evaluated in pivotal phase 3 trials. Imetelstat (telomerase inhibitor) is currently evaluated in the second line setting; OS was set as the primary endpoint, marking an unprecedented goal in MF trials, wherein SVR35 and TSS50 at 24 weeks have been typical endpoints heretofore. Transfusion independence may be considered another clinically meaningful endpoint in MF trials given its correlation with OS. Overall, therapeutics are at the cusp of an exponential expansion and advancements that will likely lead to the golden era in treatment of MF.

Pharmacotherapeutic advances for splenomegaly in myelofibrosis

INTRODUCTION

Myelofibrosis is a hematologic malignancy with a variety of clinical manifestations including splenomegaly, which is present in approximately 80% of newly diagnosed patients. JAK inhibitors are the mainstay of pharmacologic treatment for splenomegaly in myelofibrosis, although spleen size reduction is not universal, and the duration of benefit is only moderately durable.

AREAS COVERED

We first discuss the pathobiology of splenomegaly in myelofibrosis before detailing approved and novel pharmacotherapies that can reduce spleen size while also highlighting non-pharmacologic approaches. In this review, efficacy of these treatments is measured solely by spleen volume reduction, acknowledging that other outcome measures such as symptom improvement and survival are also critical.

EXPERT OPINION

Currently, ruxolitinib can be administered to the majority of frontline patients although those with severe thrombocytopenia should receive pacritinib to address spleen burden. Momelotinib may be particularly well suited for patients with significant anemia and novel combination treatments in clinical development may improve the depth and duration of spleen responses. After frontline treatment failure, fedratinib, or pacritinib are commercial options for patients with persistent symptomatic splenomegaly. Novel agents given alone or in combination with a JAK inhibitor are being explored in trials, which may ameliorate splenomegaly and ultimately improve disease progression.

2-Aminopyrimidine derivatives as selective dual inhibitors of JAK2 and FLT3 for the treatment of acute myeloid leukemia

Dual inhibitors of JAK2 and FLT3 can synergistically control the development of acute myeloid leukemia (AML), and overcome secondary drug resistance of AML that is associated with FLT3 inhibition. We therefore designed and synthesized a series of 4-piperazinyl-2-aminopyrimidines as dual inhibitors of JAK2 and FLT3, and improved their selectivity for JAK2. Screening cascades revealed that compound 11r exhibited inhibitory activity with IC₅₀ values of 2.01, 0.51, and 104.40 nM against JAK2, FLT3, and JAK3, respectively. Compound 11r achieved a high selectivity for JAK2 at a ratio of 51.94, and also showed potent antiproliferative activity in HEL (IC₅₀ = 1.10 μM) and MV4-11 (IC₅₀ = 9.43 nM) cell lines. In an in vitro metabolism assay, 11r exhibited moderate stability in human liver microsomes (HLMs), with a half-life time of 44.4 min, and in rat liver microsomes (RLMs), with a half-life of 143 min. In pharmacokinetic studies, compound 11r showed moderate absorption (Tmax = 5.33 h), with a peak concentration of 38.7 ng/mL and an AUC of 522 ng h/mL in rats, and an oral bioavailability of 25.2%. In addition, 11r induced MV4-11 cell apoptosis in a dose-dependent manner. These results indicate that 11r is a promising selective JAK2/FLT3 dual inhibitor.

JAK inhibition in myelofibrosis: how to sequence treatment in this new era of multiple options

The management of myelofibrosis has improved following approval of the JAK1/JAK2 inhibitor, ruxolitinib. This agent laid the foundation for JAK inhibitor therapy, yet limitations have included myelosuppression and other adverse events (skin cancer, weight gain, and infection), as well as loss of response. Recently, two additional JAK inhibitors were approved for use in myelofibrosis. Fedratinib can be used front-line and has demonstrated impressive responses as a salvage option after ruxolitinib loss of response. Previously, patients with severe thrombocytopenia had limited treatment options; approval of pacritinib offers an option to address splenomegaly and/or symptoms in these patients. A significant unmet need has been the treatment of anemia; momelotinib (not approved at the time of writing) has demonstrated spleen, symptom, and anemia responses. The possibility of having four approved options for myelofibrosis may be soon realized. This speaks to progress in the past decade, though achieving clinical and molecular remissions remain paramount.

Trends in overall mortality among US veterans with primary myelofibrosis

BACKGROUND

Primary myelofibrosis [PMF] is a myeloproliferative neoplasm associated with reduced overall survival (OS). Management strategies for PMF have evolved over the last two decades, including approval of ruxolitinib as the first Janus kinase 1 (JAK1)/JAK2 inhibitor for patients with intermediate or high-risk myelofibrosis. This study assessed changes in mortality before and after ruxolitinib approval, independent of ruxolitinib treatment.

METHODS

This retrospective study investigated mortality trends among US veterans with PMF in 2 time periods, pre-ruxolitinib approval (01/01/2007-12/31/2010) and post-ruxolitinib approval (01/01/2015-09/30/2018). Deidentified patient-level data were extracted from US Veterans Health Administration (VHA) databases using PMF diagnosis codes; index was the first PMF diagnosis date. The analysis included adults with ≥2 PMF claims during the analysis periods who were continuously enrolled in the VHA plan 1 calendar year prior to and 6 months post-index and had ≥1 available International Prognostic Scoring System (IPSS) risk factor (available factors were age > 65, hemoglobin < 10 g/dL, and white blood cell count > 25 × 10⁹/L; each counted as one point). Patients with ≥1 MF diagnosis for 12 months before the index period were excluded. Ruxolitinib treatment was not a requirement to be included in the post-ruxolitinib approval cohort. Mortality rates and OS were estimated using the Kaplan-Meier approach; all-cause mortality hazard ratio was estimated using univariate Cox regression.

RESULTS

The pre- and post-ruxolitinib approval cohorts included 193 and 974 patients, respectively, of which 80 and 197 had ≥2 IPSS risk factors. Ruxolitinib use in the post-ruxolitinib cohort was 8.5% (83/974). At end of follow-up, median (95% CI) OS was significantly shorter in the pre-ruxolitinib cohort (1.7 [1.2-2.6] years vs not reached [3.4-not reached]; P < 0.001). Overall mortality rates for the pre- versus post-ruxolitinib approval cohorts were 79.8% versus 47.3%, respectively, and overall risk of death was 53% lower in the post-ruxolitinib period (hazard ratio, 0.47; 95% CI, 0.37-0.58; P < 0.001). Mortality rates were lower among patients with < 2 vs ≥2 IPSS risk factors.

CONCLUSIONS

Although veterans with PMF have high overall mortality rates, and results in this population might not be generalizable to the overall population, there was a significant lowering of mortality rate in the post-ruxolitinib period.

The STAT family: Key transcription factors mediating crosstalk between cancer stem cells and tumor immune microenvironment

Signal transducer and activator of transcription (STAT) proteins compose a family of transcription factors critical for cancer stem cells (CSCs), and they are involved in maintaining stemness properties, enhancing cell proliferation, and promoting metastasis. Recent studies suggest that STAT proteins engage in reciprocal communication between CSCs and infiltrate immune cell populations in the tumor microenvironment (TME). Emerging evidence has substantiated the influence of immune cells, including macrophages, myeloid-derived suppressor cells, and T cells, on CSC survival through the regulation of STAT signaling. Conversely, dysregulation of STATs in CSCs or immune cells contributes to the establishment of an immunosuppressive TME. Thus, STAT proteins are promising therapeutic targets for cancer treatment, especially when used in combination with immunotherapy. From this perspective, we discuss the complex roles of STATs in CSCs and highlight their functions in the crosstalk between CSCs and the immune microenvironment. Finally, cutting-edge clinical trial progress with STAT signaling inhibitors is summarized.

New approaches to tackle cytopenic myelofibrosis

Myelofibrosis (MF) is a clonal hematopoietic stem cell neoplasm characterized by constitutional symptoms, splenomegaly, and risks of marrow failure or leukemic transformation and is universally driven by Jak/STAT pathway activation. Despite sharing this pathogenic feature, MF disease behavior can vary widely. MF can generally be categorized into 2 distinct subgroups based on clinical phenotype: proliferative MF and cytopenic (myelodepletive) MF. Compared to proliferative phenotypes, cytopenic MF is characterized by lower blood counts (specifically anemia and thrombocytopenia), more frequent additional somatic mutations outside the Jak/STAT pathway, and a worse prognosis. Cytopenic MF presents unique therapeutic challenges. The first approved Jak inhibitors, ruxolitinib and fedratinib, can both improve constitutional symptoms and splenomegaly but carry on-target risks of worsening anemia and thrombocytopenia, limiting their use in patients with cytopenic MF. Supportive care measures that aim to improve anemia or thrombocytopenia are often ineffective. Fortunately, new treatment strategies for cytopenic MF are on the horizon. Pacritinib, selective Jak2 inhibitor, was approved in 2022 to treat patients with symptomatic MF and a platelet count lower than 50 × 109/L. Several other Jak inhibitors are in development to extend therapeutic benefits to those with either anemia or thrombocytopenia. While many other novel non-Jak inhibitor therapies are in development for MF, most carry a risk of hematologic toxicities and often exclude patients with baseline thrombocytopenia. As a result, significant unmet needs remain for cytopenic MF. Here, we discuss clinical implications of the cytopenic MF phenotype and present existing and future strategies to tackle this challenging disease.

Safety and efficacy of jaktinib in the treatment of Janus kinase inhibitor-naïve patients with myelofibrosis: Results of a phase II trial

Myelofibrosis (MF) is associated with several constitutional symptoms. Currently, there are few therapeutic options for MF. Jaktinib, a novel, small-molecule inhibitor of JAK, is currently being studied for its potential to treat MF. This phase 2 trial investigated efficacy and safety of jaktinib in the treatment of MF patients. The primary end point was the proportion of patients with ≥35% reduction in spleen volume (SVR35, proportion of patients with ≥35% reduction in spleen volume) at week 24. The secondary end points included improvement of anemia, rates of symptom response, and safety profile. Between January 8, 2019 and August 29, 2020, 118 patients were recruited and treated with either jaktinib 100 mg BID or 200 mg QD. At week 24, 54.8% (34/62) of patients in the 100 mg BID group and 31.3% (15/48) in the 200 mg QD group achieved SVR35 (p = .0199). Jaktinib treatment increased hemoglobin level to ≥20 g/L in 35.6% (21/59) of patients with hemoglobin ≤100 g/L at baseline. The proportion of patients who achieved a ≥50% improvement in total symptom score at week 24 was 69.6% (39/56) in the BID group and 57.5% (23/40) in the QD group. The most common ≥ grade 3 hematological treatment-emergent adverse events (TEAEs; ≥ 10%) were anemia (100 mg BID: 24.2%, 200 mg QD: 28.8%), thrombocytopenia (16.7%, 11.5%), and neutropenia (3.0%, 11.5%). All non-hematological TEAEs were mild. These results indicate that jaktinib can shrink the spleen, improve anemia, and other clinical symptoms with good tolerability.

Novel therapeutic agents for myelofibrosis after failure or suboptimal response to JAK2 inhbitors

PURPOSE OF REVIEW

JAK2 inhibitors have changed the therapeutic strategies for the management of primary and secondary myelofibrosis. Ruxolitinib, the first available agent, improved disease-related symptoms, spleen volume, and overall survival compared to conventional chemotherapy. It has been revealed that after 3 years of treatment, about 50% of patients discontinued ruxolitinib for resistance and/or intolerance and should be candidate to a second line of treatment.

RECENT FINDINGS

Second-generation tyrosine kinase inhibitors have been tested in this setting, but all these new drugs do not significantly impact on disease progression. Novel agents are in developments that target on different pathways, alone or in combination with JAK2 inhibitors.

SUMMARY

In this review, we summarize all the clinical efficacy and safety data of these drugs providing a vision of the possible future.

Fedratinib: a pharmacotherapeutic option for JAK-inhibitor naïve and exposed patients with myelofibrosis

INTRODUCTION

Ruxolitinib is the most commonly used JAK-inhibitor (JAKi) for the management of symptoms related to splenomegaly and cytokine-mediated inflammation in patients with myelofibrosis (MF), but is limited by variable durability of response with most patients experiencing failure after 2-3 years. Long-term data on other approved JAKi, fedratinib and pacritinib, are not available due to the clinical hold put on pivotal trials for toxicity concerns.

AREAS COVERED

Following the initial hold for concern of Wernicke's encephalopathy, fedratinib was approved by the Food and Drug Administration (FDA) in 2019 for MF. We review the data available from early, and late phase critical trials, outline a role for fedratinib in the current treatment landscape of MF, and highlight the knowledge gaps in optimizing use of fedratinib.

EXPERT OPINION

The JAKARTA and JAKARTA2 trials established efficacy in spleen volume response (SVR) and symptom reduction in JAKi-naïve and ruxolitinib-exposed MF patients, respectively. Further trials, FREEDOM and FREEDOM2, are in progress to understand long-term effects of fedratinib; and include strategies to mitigate gastrointestinal toxicity, monitor thiamine levels and surveil for encephalopathy. We use fedratinib for symptomatic MF following ruxolitinib failure in patients without significant cytopenias; with practical strategies for monitoring and managing potential toxicity.

Myeloproliferative Neoplasms, Version 3.2022, NCCN Clinical Practice Guidelines in Oncology

The classic Philadelphia chromosome-negative myeloproliferative neoplasms (MPN) consist of myelofibrosis, polycythemia vera, and essential thrombocythemia and are a heterogeneous group of clonal blood disorders characterized by an overproduction of blood cells. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for MPN were developed as a result of meetings convened by a multidisciplinary panel with expertise in MPN, with the goal of providing recommendations for the management of MPN in adults. The Guidelines include recommendations for the diagnostic workup, risk stratification, treatment, and supportive care strategies for the management of myelofibrosis, polycythemia vera, and essential thrombocythemia. Assessment of symptoms at baseline and monitoring of symptom status during the course of treatment is recommended for all patients. This article focuses on the recommendations as outlined in the NCCN Guidelines for the diagnosis of MPN and the risk stratification, management, and supportive care relevant to MF.

The odyssey of pacritinib in myelofibrosis

Myelofibrosis (MF) can present with symptomatic splenomegaly and/or cytopenias including thrombocytopenia. Disease-related thrombocytopenia is a poor prognostic factor with a median overall survival of less than 2 years. Currently approved JAK1/2 inhibitors have not been evaluated in patients with platelets ≤ 50 × 109/L and in fact could potentiate thrombocytopenia because of their combined JAK1/2 inhibitory activity. Pacritinib (PAC), a selective JAK2, fms-like tyrosine kinase 3, interleukin-1 receptor-associated kinase 1 multikinase inhibitor was developed to meet this unmet need. PAC was evaluated in 2 randomized phase 3 trials in the frontline setting (PERSIST-1, PAC 400 mg daily vs best available therapy) and second-line setting in patients with MF with platelets ≤ 100 × 109/L (PERSIST-2, PAC 400 mg daily or 200 mg twice daily vs best available therapy). PERSIST-1 met its primary end point; however, the development of PAC hit a brief pause because of a US Food and Drug Administration-mandated clinical hold for excess of bleeding and cardiac events in the PAC 400 mg daily arm in the PERSIST-1 study. Although the PERSIST-2 study was terminated abruptly because of this clinical hold, it met its splenic response end point and demonstrated a trend toward symptom improvement. Subsequent, diligent review of the PERSIST-1 and PERSIST-2 studies did not confirm an excess of severe bleeding or cardiac events on the PAC arm. Additionally, the dose finding PAC203 study endorsed the safety and efficacy of 200 mg twice daily, leading to the approval of PAC for the treatment of patients with MF with platelets ≤ 50 × 109/L.

Pacritinib for the treatment of patients with myelofibrosis and thrombocytopenia

INTRODUCTION

: Myelofibrosis (MF) is a rare myeloproliferative neoplasm characterized by a complex symptom profile, cytopenias, splenomegaly, and potential for leukemic progression. Severe thrombocytopenia is common in patients with MF and correlates with poor prognosis; however, until recently, treatment options for these patients were limited. Pacritinib, a potent Janus kinase (JAK) 2/interleukin-1 receptor-associated kinase 1 (IRAK1) inhibitor, has demonstrated significant reduction in splenomegaly, improved symptom control, and a manageable safety profile in patients with MF regardless of the severity of thrombocytopenia.

AREAS COVERED

: This review will outline the pacritinib drug profile and summarize key efficacy and safety data, focusing on the 200 mg twice daily dose from phase 2 and 3 studies that formed the basis for the recent US Food and Drug Administration approval of pacritinib in patients with MF and severe thrombocytopenia (platelet counts <50 x 10⁹/L).

EXPERT OPINION

Pacritinib, with its unique mechanism of action targeting both JAK2 and IRAK1, offers patients with MF and severe thrombocytopenia a new treatment option, providing consistent disease and symptom control. Adverse events are easily manageable. Further analyses to identify ideal patient characteristics for pacritinib and other JAK inhibitors along with studies of pacritinib combinations are warranted, including in related myeloid malignancies.

JAK2 Alterations in Acute Lymphoblastic Leukemia: Molecular Insights for Superior Precision Medicine Strategies

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer, arising from immature lymphocytes that show uncontrolled proliferation and arrested differentiation. Genomic alterations affecting Janus kinase 2 (JAK2) correlate with some of the poorest outcomes within the Philadelphia-like subtype of ALL. Given the success of kinase inhibitors in the treatment of chronic myeloid leukemia, the discovery of activating JAK2 point mutations and JAK2 fusion genes in ALL, was a breakthrough for potential targeted therapies. However, the molecular mechanisms by which these alterations activate JAK2 and promote downstream signaling is poorly understood. Furthermore, as clinical data regarding the limitations of approved JAK inhibitors in myeloproliferative disorders matures, there is a growing awareness of the need for alternative precision medicine approaches for specific JAK2 lesions. This review focuses on the molecular mechanisms behind ALL-associated JAK2 mutations and JAK2 fusion genes, known and potential causes of JAK-inhibitor resistance, and how JAK2 alterations could be targeted using alternative and novel rationally designed therapies to guide precision medicine approaches for these high-risk subtypes of ALL.

Fedratinib, the first selective JAK2 inhibitor approved for treatment of myelofibrosis - an option beyond ruxolitinib

Introduction: Myelofibrosis, a life shortening clonal disorder, presents with a constellation of features: bone marrow fibrosis, abnormal blood counts, extramedullary hematopoiesis, splenomegaly, thrombohemorrhagic complications and constitutional symptoms. Until recently Ruxolitinib, a JAK1 and 2 inhibitor, has been the only targeted therapy available for transplant-ineligible patients requiring treatment for splenomegaly and disease related symptoms. However, most patients discontinue Ruxolitinib after 3-5 years, mostly due to loss of response. There has been an unmet need for this patient group. In August 2019 Fedratinib (INREBIC® capsules, Impact Biomedicines, Inc., a wholly owned subsidiary of Bristol Meyer Squibb), a JAK2 inhibitor, was approved by US FDA for treatment of myelofibrosis in both JAK inhibitor naïve and pre-treated patients for the management of symptoms and splenomegaly.Areas covered: Here, we discuss the development, evidence base to date for Fedratinib. Including early and late phase, and ongoing trials, safety issues, potential role and current position of Fedratinib in the treatment of myelofibrosis, as well as future direction of targeted therapy in myelofibrosis.Expert opinion: Fedratinib presents a much needed option of treatment, particularly, for patients failing Ruxolitinib, with response rates that are quite similar. Nonetheless, there remain important questions including sequencing and options for combining therapy.