Targeting of the Hedgehog pathway in myeloid malignancies: still a worthy chase?

Deregulated Hedgehog (Hh) signalling activity may be associated with a broad range of cancer types and hence has become an attractive target for therapeutic intervention. Although initial haematological interest focused on the therapeutic targeting of this pathway in chronic myeloid leukaemia), small molecule inhibitors targeting the Hh pathway are now being tested in a range of other myeloid disorders, including myelofibrosis, myelodysplasia and acute myeloid leukaemia. In this review we will evaluate the rationale for targeting of the Hh pathway in myeloid diseases and discuss the novel agents that have entered the clinical arena. We will discuss pre-clinical models, emerging clinical trial data, and suggest how these targeted therapies may address current unmet medical needs. Finally, we will explore potential limitations of these therapies due to the emergence of secondary resistance mechanisms and speculate on future developments within this arena.

Splenomegaly in patients with primary or secondary myelofibrosis who are candidates for allogeneic hematopoietic cell transplantation: a Position Paper on behalf of the Chronic Malignancies Working Party of the EBMT

Splenomegaly is a hallmark of myelofibrosis, a debilitating haematological malignancy for which the only curative option is allogeneic haematopoietic cell transplantation (HCT). Considerable splenic enlargement might be associated with a higher risk of delayed engraftment and graft failure, increased non-relapse mortality, and worse overall survival after HCT as compared with patients without significantly enlarged splenomegaly. Currently, there are no standardised guidelines to assist transplantation physicians in deciding optimal management of splenomegaly before HCT. Therefore, the aim of this Position Paper is to offer a shared position statement on this issue. An international group of haematologists, transplantation physicians, gastroenterologists, surgeons, radiotherapists, and radiologists with experience in the treatment of myelofibrosis contributed to this Position Paper. The key issues addressed by this group included the assessment, prevalence, and clinical significance of splenomegaly, and the need for a therapeutic intervention before HCT for the control of splenomegaly. Specific scenarios, including splanchnic vein thrombosis and COVID-19, are also discussed. All patients with myelofibrosis must have their spleen size assessed before allogeneic HCT. Myelofibrosis patients with splenomegaly measuring 5 cm and larger, particularly when exceeding 15 cm below the left costal margin, or with splenomegaly-related symptoms, could benefit from treatment with the aim of reducing the spleen size before HCT. In the absence of, or loss of, response, patients with increasing spleen size should be evaluated for second-line options, depending on availability, patient fitness, and centre experience. Splanchnic vein thrombosis is not an absolute contraindication for HCT, but a multidisciplinary approach is warranted. Finally, prevention and treatment of COVID-19 should adhere to standard recommendations for immunocompromised patients.

Current and future role of fedratinib in the treatment of myelofibrosis

Fedratinib (INREBIC^® [fedratinib] capsules, Impact Biomedicines, Inc., a wholly owned subsidiary of Celgene Corporation), is a potent JAK2 inhibitor that has been approved for use in myelofibrosis, both as a first-line agent and also in second line following ruxolitinib (Novartis Pharmaceuticals, Basel, Switzerland) failure or intolerance. Within this article, we will review relevant preclinical and early/late clinical trial data concerning the use of fedratinib to treat myeloproliferative neoplasms. Moreover, we will review in detail the assumed safety issues that led to temporary cessation of all programs with the agent in 2013 which subsequently re-entered the clinical arena in 2017. We will discuss how physicians may safely transition a patient across from ruxolitinib to fedratinib following intolerance or lack of efficacy. At last, we will discuss potential future applications of this agent within the field.

Practice harmonization workshops of EBMT: an expert-based approach to generate practical and contemporary guidelines within the arena of hematopoietic cell transplantation and cellular therapy

For hematopoietic cell transplantation (HCT) and cellular therapy (CT), clinical patient care is localized, and practices may differ between countries and from center to center even within the same country. Historically, international guidelines were not always adapted to the changing daily clinical practice and practical topics there were not always addressed. In the absence of well-established guidelines, centers tended to develop local procedures/policies, frequently with limited communication with other centers. To try to harmonize localized clinical practices for malignant and non-malignant hematological disorders within EBMT scope, the practice harmonization and guidelines (PH&G) committee of the EBMT will co-ordinate workshops with topic-specific experts from interested centers. Each workshop will discuss a specific issue and write guidelines/recommendations that practically addresses the topic under review. To provide clear, practical and user-friendly guidelines when international consensus is lacking, the EBMT PH&G committee plans to develop European guidelines by HCT and CT physicians for peers’ use. Here, we define how workshops will be conducted and guidelines/recommendations produced, approved and published. Ultimately, there is an aspiration for some topics, where there is sufficient evidence base to be considered for systematic reviews, which are a more robust and future-proofed basis for guidelines/recommendations than consensus opinion.

Current and future therapies for myelofibrosis

Myelofibrosis is classified as a 'Philadelphia-chromosome negative' clonal myeloproliferative disorder. The heterogeneity of this condition and patient population and array of often challenging clinical manifestations can frequently make therapeutic decisions challenging. Despite many advances in therapy with targeted and combination approaches, following an enhanced understanding of underlying disease pathogenesis, cure only remains achievable with allogeneic stem cell transplant. This option is often limited to a small group of younger transplant-eligible patients with more advanced disease who have both a suitable donor and no or few co-morbidities. In this article, we will discuss up-to-date disease prognostication, common clinical challenges associated with myelofibrosis and both standard and novel therapeutic approaches. Increasingly complex prognostic modelling utilises patient-specific, haematological and genomic parameters to improve the accuracy of risk assessment and predict disease progression. We will also focus on difficult clinical scenarios such as disease-associated anaemia, thrombocytopenia and extremes of age. Future and evolving therapies within this field are highly anticipated and novel JAK inhibitor and non-JAK inhibitor-based therapy will also be discussed, including the new challenge of how to switch from one JAK inhibitor therapy to another.

Pneumonitis post-haematopoeitic stem cell transplant - cytopathology clinches diagnosis

BACKGROUND

Primary BK virus (BKV) infection is probably acquired by the respiratory route in childhood, and latent virus persists principally in the urinary tract. BKV reactivation is implicated in late onset haemorrhagic cystitis (HC) post Haematopoietic Stem Cell Transplant (HSCT). There is emerging evidence that BKV can cause life-threatening pneumonitis in immunocompromised individuals.

OBJECTIVES

To describe the first known case of BKV pneumonitis in an adult HSCT recipient.

STUDY DESIGN/RESULTS

A 19-year old male underwent an ABO-incompatible, volunteer unrelated donor allogeneic HSCT for high risk AML. The post-transplant period was complicated by moderate-severe cutaneous and gut acute graft-versus-host disease (aGVHD) and severe HC, attributable to BKV. Treatment encompassed intensification of immunosupression for aGVHD and weekly intravenous (IV) cidofovir (2.5mg/Kg) for BK viruria. He was readmitted with presumed septic shock and acute renal failure. After a transient improvement on broad spectrum antibacterials, he suffered significant respiratory deterioration. CT imaging revealed diffuse 'ground-glass' attenuation. Cytopathological assessment of a broncho-alveolar sample (BAL) was consistent with polyomavirus pneumonitis. No other cause was found to account for the respiratory deterioration. He did not respond to therapy and died of multi-organ failure.

CONCLUSIONS

BKV is implicated in haemorrhagic cystitis in HSCT recipients but not routinely considered as a cause of pneumonitis. There are just 5 other cases in the literature, including 3 patients with AIDS. BKV should be considered as a possible cause of pneumonitis in HSCT recipients.

Altered immune response to the annual influenza A vaccine in patients with myeloproliferative neoplasms

The seasonal influenza A vaccine is recommended for patients with myeloproliferative neoplasms (MPNs). We hypothesised that immune deregulation associated with MPNs may affect the immune response gained following vaccinations when compared to healthy controls. Using deep immunophenotyping with high-dimensional single-cell analysis and mass cytometry we could demonstrate an altered immune response in MPN patients following vaccination. We found that prior to vaccination, MPN patients had reduced numbers of naive CD4 T cells. Furthermore, at 3-weeks and 3-months post-vaccination there was evidence of both delayed and impaired B- and T-memory cells responses. Thus, although, the immune systems of MPN patients can 'recognise' the Influenza A vaccine, the response appears inferior compared to healthy controls.

Symptomatic benefit of momelotinib in patients with myelofibrosis: Results from the SIMPLIFY phase III studies

BACKGROUND

Myelofibrosis (MF)-associated constitutional symptoms can severely impact health-related quality of life. Clinical trials in MF traditionally measure symptom response to treatment as a landmark endpoint of total symptom score (TSS) reduction ≥50% from baseline. However, this dichotomous assessment provides a limited view of clinically relevant symptomatic changes. Herein we evaluated longitudinal change from baseline in TSS over the continuous 24-week period and individual symptom scores to obtain a more comprehensive understanding of symptom benefits experienced by patients with MF receiving therapy.

METHODS

Longitudinal symptom change was evaluated using mixed-effect model repeated measure (MMRM) methodology with individual item-level analyses to complement the interpretation of the landmark symptom results in the completed phase III SIMPLIFY studies of momelotinib in MF. MMRM compared mean change in TSS from baseline with Week 24 using data from all patient visits. Generalized estimating equations were used to estimate item-level odds ratios using multiple predictive imputations for missing data.

RESULTS

Momelotinib and ruxolitinib groups reported similar overall symptom improvements, with a TSS difference of <1.5 points between groups for each post-baseline visit in SIMPLIFY-1. In SIMPLIFY-2, the improvement in TSS observed in momelotinib-treated patients was consistent with that observed in SIMPLIFY-1, whereas progressive TSS deterioration was observed with control. Item-level scores were heterogeneous in both studies. A similar and greater proportion of momelotinib-treated patients were categorized as "improved" or "stable" compared with control in SIMPLIFY-1 and SIMPLIFY-2, respectively. Odds ratios for between-group comparison ranged from 0.75 to 1.21 in SIMPLIFY-1, demonstrating similarity in likelihood of symptom improvement. In SIMPLIFY-2, the likelihood of symptom improvement in each item was higher in the momelotinib arm.

CONCLUSIONS

These findings suggest that momelotinib provides clinically relevant symptom benefits in the JAK inhibitor-naïve and JAK inhibitor-exposed settings.

MOMENTUM: Phase 3 randomized study of momelotinib (MMB) versus danazol (DAN) in symptomatic and anemic myelofibrosis (MF) patients previously treated with a JAK inhibitor

7002

Background: MMB, an oral JAK1/2 and ACVR1/ALK2 inhibitor, showed clinical activity on MF symptoms, RBC transfusion requirements (anemia), and spleen volume in the SIMPLIFY trials. This pivotal phase 3 study of MF patients (pts) previously treated with a JAK inhibitor (JAKi) tested MMB vs DAN on key symptom, anemia, and spleen volume endpoints at 24 weeks (wks). Methods: Eligibility: Primary or post-ET/PV MF; DIPSS high risk, Int-2, or Int-1; MF Symptom Assessment Form Total Symptom Score (MFSAF TSS) ≥10; Hgb <10 g/dL; prior JAKi for ≥90 days, or ≥28 days if RBC transfusions ≥4 units in 8 wks or Gr 3/4 thrombocytopenia, anemia, or hematoma; palpable spleen ≥5 cm. Stratification: TSS, palpable spleen, and RBC units transfused. JAKi taper and washout was ≥21 days. Randomization: 2:1 to MMB 200 mg QD plus DAN placebo or DAN 600 mg QD plus MMB placebo for 24 wks, after which pts could receive open-label MMB. Assessments: Pt reported symptoms using a daily eDiary and spleen volume by MRI or CT. The primary endpoint was TSS response (≥50% reduction from baseline [BL]) rate at wk 24. Secondary endpoints, assessed sequentially at wk 24, were RBC transfusion independence (TI) rate, splenic response rate (SRR; ≥25% reduction in volume from BL), change from BL in TSS, SRR (≥35% reduction from BL) and rate of zero transfusions since BL. Results: 94 of 130 (72%) MMB pts and 38 of 65 (58%) DAN pts completed the 24-wk randomized treatment (RT) phase. Median BL TSS were 28 (MMB) and 26 (DAN), Hgb were 8.1 (MMB) and 7.9 (DAN) g/dL, and platelets were 97 (MMB) and 94 (DAN) x109/L. BL TI was 13% (MMB) and 15% (DAN). Prior JAKi was ruxolitinib in 195 pts (100%) and fedratinib in 9 pts (5%). All primary and key secondary endpoints were met (Table). Most common Gr ≥3 TEAEs in the RT phase of the study were thrombocytopenia (MMB, 22%; DAN, 12%) and anemia (MMB, 8%; DAN, 11%). Gr ≥3 infections occurred in 15% of MMB and 17% of DAN pts. Peripheral neuropathy occurred in 5 (4%) of MMB (all Gr ≤2) and 1 (2%) of DAN (Gr ≤2) pts in the RT phase, and none discontinued study drug. Overall, TEAEs led to study drug discontinuation in 18% of MMB and 23% of DAN pts in RT phase. A trend toward improved OS up to wk 24 was seen with MMB vs DAN (HR=0.506, p=0.0719). Conclusions: In symptomatic and anemic MF pts, MMB was superior to DAN for symptom responses, transfusion requirements, and spleen responses with comparable safety and favorable survival. MMB may address a critical unmet need, particularly in MF pts with anemia. Clinical trial information: NCT04173494. [Table: see text]

A simple prognostic system in patients with myelofibrosis undergoing allogeneic stem cell transplantation: a CIBMTR/EBMT analysis

To develop a prognostic model for patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT) for myelofibrosis (MF), we examined the data of 623 patients undergoing allo-HCT between 2000 and 2016 in the United States (the Center for International Blood and Marrow Transplant Research [CIBMTR] cohort). A Cox multivariable model was used to identify factors prognostic of mortality. A weighted score using these factors was assigned to patients who received transplantation in Europe (the European Bone Marrow Transplant [EBMT] cohort; n = 623). Patient age >50 years (hazard ratio [HR], 1.39; 95% confidence interval [CI], 0.98-1.96), and HLA-matched unrelated donor (HR, 1.29; 95% CI, 0.98-1.7) were associated with an increased hazard of death and were assigned 1 point. Hemoglobin levels <100 g/L at time of transplantation (HR, 1.63; 95% CI, 1.2-2.19) and a mismatched unrelated donor (HR, 1.78; 95% CI, 1.25-2.52) were assigned 2 points. The 3-year overall survival (OS) in patients with a low (1-2 points), intermediate (3-4 points), and high score (5 points) were 69% (95% CI, 61-76), 51% (95% CI, 46-56.4), and 34% (95% CI, 21-49), respectively (P < .001). Increasing score was predictive of increased transplant-related mortality (TRM; P = .0017) but not of relapse (P = .12). The derived score was predictive of OS (P < .001) and TRM (P = .002) but not of relapse (P = .17) in the EBMT cohort as well. The proposed system was prognostic of survival in 2 large cohorts, CIBMTR and EBMT, and can easily be applied by clinicians consulting patients with MF about the transplantation outcomes.

Evaluating the Safety, Efficacy, and Therapeutic Potential of Momelotinib in the Treatment of Intermediate/High-Risk Myelofibrosis: Evidence to Date

Myelofibrosis is a heterogeneous disorder with regard to both molecular pathogenesis and clinical phenotype, ranging from an initial fairly indolent condition in some through to an aggressive and debilitating scenario with profound constitutional symptoms, cytopenia frequently requiring transfusional support, and massive splenomegaly. Many advances have been made within the therapeutic arena, and an increasing array of novel agents are now available for disease management. Within this review, we focus on the current and predicted role of the JAK inhibitor momelotinib (Sierra Oncology) in myelofibrosis, with an emphasis on clinical trial evaluation, drug efficacyand safety, and discuss the suggested place in the therapeutic paradigm of myelofibrosis in 2020 and beyond.

Allogeneic hematopoietic cell transplantation in patients with chronic phase chronic myeloid leukemia in the era of third generation tyrosine kinase inhibitors: A retrospective study by the chronic malignancies working party of the EBMT

Following the introduction of tyrosine kinase inhibitors (TKI), the number of patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT) for chronic phase (CP) chronic myeloid leukemia (CML) has dramatically decreased. Imatinib was the first TKI introduced to the clinical arena, predominantly utilized in the first line setting. In cases of insufficient response, resistance, or intolerance, CML patients can subsequently be treated with either a second or third generation TKI. Between 2006 and 2016, we analyzed the impact of the use of 1, 2, or 3 TKI prior to allo-HCT for CP CML in 904 patients. A total of 323-, 371-, and 210 patients had 1, 2, or 3 TKI prior to transplant, respectively; imatinib (n = 778), dasatinib (n = 508), nilotinib (n = 353), bosutinib (n = 12), and ponatinib (n = 44). The majority had imatinib as first TKI (n = 747, 96%). Transplants were performed in CP1, n = 549, CP2, n = 306, and CP3, n = 49. With a median follow-up of 52 months, 5-year OS for the entire population was 64.4% (95% CI 60.9-67.9%), PFS 50% (95% CI 46.3-53.7%), RI 28.7% (95% CI 25.4-32.0%), and NRM 21.3% (95% CI 18.3-24.2%). No difference in OS, PFS, RI, or NRM was evident related to the number of TKI prior to allo-HCT or to the type of TKI (p = ns). Significant factors influencing OS and PFS were > CP1 versus CP1 and Karnofsky performance (KPS) score > 80 versus ≤80, highlighting CP1 patients undergoing allo-HCT have improved survival compared to >CP1 and the importance of careful allo-HCT candidate selection.

Pacritinib: a new agent for the management of myelofibrosis?

INTRODUCTION

Myelofibrosis (MF) is a clonal haematological disease associated with recurrent somatic gene mutations (JAK2V617F, MPL, CALR) and constitutive activation of the Janus kinase (JAK)/Signal Transducer and Activator of Transcription pathway. MF is often characterised by debilitating symptoms and JAK inhibitors (JAKIs) have revolutionised available therapeutic options. Ruxolitinib, a JAK1 and 2 inhibitor, is the only currently approved agent. Several other JAKIs are undergoing evaluation in the clinical trial setting and Pacritinib , a novel JAK2 and FLT3 inhibitor, is at an advanced stage of investigation with recent completion of a Phase III trial and another ongoing.

AREAS COVERED

Within this article we focus on pacritinib, summarising the development, preclinical and up-to-date results from the Phase I - III trials. We present the most recent data on efficacy and safety and indirectly compare this novel JAKI with ruxolitinib.

EXPERT OPINION

The kinome array data for pacritinib suggests that it has a range of targets differing to those for ruxolitinib. Pacritinib appears to be an effective agent for the control of MF-related symptoms and splenomegaly with potentially fewer haematological side-effects when compared with ruxolitinib and seems a particularly promising agent for anaemic and thrombocytopenic patients. It is also an attractive drug for potential combination studies due to its good tolerability.

Clinicopathological characterisation of myeloproliferative neoplasm-unclassifiable (MPN-U): a retrospective analysis from a large UK tertiary referral centre

Myeloproliferative neoplasm-unclassifiable (MPN-U) presents an MPN-type phenotype that fails to meet diagnostic criteria for other MPN variants. Variability in the clinicopathological phenotypes presents many challenges. Amongst a registry cohort of 1512 patients with MPN, 82 with MPN-U were included, with a median (range) age of 49·7 (13-79) years. Albeit heterogeneous, common presentation features included raised lactate dehydrogenase, thrombocytosis and clustered/pleomorphic megakaryocytes on trephine biopsy. Thrombosis was common (21%), necessitating vigilance. The median event-free survival was 11·25 years (95% confidence interval 9·3-not reached), significantly shortened in cases with lower platelet counts (<500 × 10⁹ /l) and a leucocytosis (≥12 × 10⁹ /l) at presentation. Generation of potential MPN-U prognostic scores is required.

Germline predisposition traits in allogeneic hematopoietic stem-cell transplantation for myelodysplastic syndromes: a survey-based study and position paper on behalf of the Chronic Malignancies Working Party of the EBMT

The recent application of whole exome or whole genome sequencing unveiled a plethora of germline variants predisposing to myeloid disorders, particularly myelodysplastic neoplasms. The presence of such variants in patients with myelodysplastic syndromes has important clinical repercussions for haematopoietic stem-cell transplantation, from donor selection and conditioning regimen to graft-versus-host disease prophylaxis and genetic counselling for relatives. No international guidelines exist to harmonise management approaches to this particular clinical scenario. Moreover, the application of germline testing, and how this informs clinical decisions, differs according to the expertise of individual clinical practices and according to different countries, health-care systems, and legislations. Leveraging the global span of the European Society for Blood and Marrow Transplantation (EBMT) network, we took a snapshot of the current European situation on these matters by disseminating an electronic survey to EBMT centres experienced in myelodysplastic syndromes transplantation. An international group of haematologists, transplantation physicians, paediatricians, nurses, and experts in molecular biology and constitutional genetics with experience in myelodysplastic syndromes contributed to this Position Paper. The panel met during multiple online meetings to discuss the results of the EBMT survey and to establish suggested harmonised guidelines for such clinical situations, which are presented here.

Essential thrombocythaemia treated with recombinant interferon: 'real world' United Kingdom referral centre experience

Standard first-line therapy choice for essential thrombocythaemia (ET) requiring cytoreduction, supported by randomized trials, is low-dose aspirin with hydroxycarbamide, but the role of recombinant interferon-alfa (IFNα)-2a/2b and pegylated (PEG)-IFN-α-2a/2b is increasingly highlighted. Longer-term outcome data, however, remains somewhat scarce, particularly in the 'real world'. We hereby report on a large, well-annotated cohort of ET patients from a single referral centre undergoing therapy with either IFNα or (PEG)-IFN-α-2a/2b and demonstrate high rates of complete haematological responses, good tolerability and safety, low rates of thromboembolic events in compliant patients and confirm feasibility of long-term therapy in a significant proportion of patients.

An early post-transplant relapse prediction score in multiple myeloma: a large cohort study from the chronic malignancies working party of EBMT

Early relapse (ER) following Autologous Hematopoietic Cell Transplantation (AHCT) confers a poor prognosis. We therefore developed a novel scoring system to predict ER. A total of 14,367 AHCT-1 patients were transplanted between 2014 and 2019, and were conditioned with Melphalan 200 mg/m2 (Mel200) (n = 7228; 2014-2017) (training cohort); Mel200 (n = 5616; 2018-2019) or Mel140 (n = 1523; 2018-2019) (validation cohorts). PFS-12 and the Cumulative Incidence of Relapse at 12 months were 84.1% and 14.7% (training Mel200), 87.2% and 11.6% (validation Mel200), and 80.3% and 16.9% (validation Mel140), respectively. The points in the risk score were: 0, 1,2 for ISS stages I, II, and III; Disease status: 0 (CR/VGPR); 1 (PR); 2 (SD/MR); 4 (Relapse/Progression); and 1 for Karnofsky ≤ 70. The distribution of scores: 0 (24%), 1 (33.9%), 2 (29.6 %), 3 (9.5%), and ≥4 (2.7%). The score separated PFS-12, with the lowest risk group (n = 1752) having a PFS-12 of 91.7% and the highest risk group (n = 195) 57.1%. This also applied in cytogenetically high-risk patients. If the pre-score baseline risks are 15% (standard risk) and 25% (high-risk), a score of ≥4 confers calculated risks of 38% and 54%, respectively. This novel EBMT ER score, therefore, allows for the identification of five discrete prognostic groups.

Forging ahead or moving back: dilemmas and disappointments of novel agents for myeloproliferative neoplasms

The common 'Philadelphia chromosome'-negative myeloproliferative neoplasms (MPN) comprise essential thrombocythaemia, polycythaemia vera and myelofibrosis. These are clinically diverse disorders and present many challenges during their course, ranging from the management of very indolent, chronic-phase disease through to very aggressive stages frequently associated with poor quality of life, heavy symptom burdens and potentially life expectancies of <18 months. Their management also requires expertise in thrombosis and haemostasis in addition to marrow failure, debilitating symptom control and balancing the 'pros and cons' of intensive therapy such as allogeneic stem cell transplant versus novel and established therapies. In the past 15 years this field has seen rapid advances following an understanding of the pivotal importance of constitutive Janus kinase/signal transducers and activators of transcription (JAK/STAT) signalling, the interplay of the wider genomic landscape and the development of updated diagnostic criteria, prognostic scores and targeted therapies. In this article, we review the successes and failures of novel agents and approaches to MPN management.