Cross, Nicholas C.P.

Abstract “Nonclassical” myeloproliferative neoplasms (MPNs) and myelodysplastic/myeloproliferative neoplasms (MDS/MPNs) represent a heterogeneous group of malignancies characterized by a wide range of clinical manifestations. Unlike classical MPNs, there is no standardized management approach for these conditions, particularly concerning the indications for and management of allogeneic hematopoietic cell transplantation. To address this gap, the European Society for Blood and Marrow Transplantation (EBMT) Practice Harmonization and Guidelines (PH&G) Committee and the Chronic Malignancies Working Party (CMWP) have collaborated to develop shared guidelines aimed at optimizing the selection and management of patients with these rare forms of neoplasms. A comprehensive review of the literature from the publication of the revised fourth edition of the (2016) World Health Organization classification onward was conducted. A multidisciplinary group of experts in the field convened to produce this document, which was developed through multiple rounds of draft circulation. Key recommendations include the early identification of potential transplant candidates, particularly in cases of chronic neutrophilic leukemia, chronic eosinophilic leukemia (CEL)/CEL, not otherwise specified (CEL-NOS), myeloid/lymphoid neoplasm with eosinophilia and tyrosine kinase gene fusions with FGFR1, JAK2, ABL1, and FLT3 rearrangements, MDS/MPN with neutrophilia/atypical chronic myeloid leukemia, and MDS/MPN, NOS. For patients with MPN, NOS/MPN unclassifiable, standard recommendations for myelofibrosis should be applied. Similarly, in MDS/MPN with thrombocytosis, transplantation is recommended on the basis of established MDS guidelines. Given the current lack of robust evidence, this document will serve as a valuable resource to guide future research activities, providing a framework for addressing critical unanswered questions and advancing the field.

Abstract Background The median survival (OS) of patients with primary myelofibrosis (PMF; 6.5y) is significantly shortened compared to reference population (Cervantes et al, JCO 2012; 30:2981). OS is predicted by the four risk categories of IPSS, Dynamic-IPSS and DIPSS-plus score, nevertheless pts heterogeneity persists within these categories, necessitating improved risk stratification. We recently reported that pts harboring mutations in any one of the prognostically relevant ASXL1, EZH2, IDH1/2 and SRSF2 genes constitute a IPSS-and DIPPS-plus independent Molecular High Risk category (MHR+) characterized by significant reduction of OS and leukemia free survival (LFS) (Vannucchi et al, Leukemia 2013). The aim of this work was to analyze the impact of the number of prognostically relevant mutated genes on OS and LFS in PMF. Patients and methods Two independent cohorts are included, a “test cohort” from Europe, analyzed at diagnosis, and a “validation cohort” from Mayo Clinic, analyzed at any time after diagnosis. Mutation analysis was performed in DNA from whole blood or granulocytes using RTQ-PCR, HRM and direct sequencing; all mutations were confirmed at least twice. The prognostic value of the molecular variables with regard to OS and LFS was analyzed by Cox regression. Test cohort It included 490 pts (median age 61y; males = 301) risk stratified by IPSS into high (n=74, 15%), intermediate-2 (n=93, 19% ), intermediate-1 (n=147, 30%) and low (n=176, 36%). The median follow-up was 3.63y (95% CI, 0.06-28.33); 161 pts died (33.0%), of whom 76 (15.6%) had progressed to acute leukemia after a median of 3.4y (0.04-28.3) from diagnosis. One hundred forty-six pts (29.8%) presented at least one of the four aforementioned mutated genes and were classified as MHR+. The OS of MHR+ pts was significantly reduced compared to patients with no mutations (n=344): 80.7 vs 148.9 mo (HR 2.2, CI95% 1.6-3.03). One hundred twelve (22.8%) pts had 1 mutation and 34 (6.9%) had 2 or more mutations. In univariate analysis presence of 2 or more mutated genes was significantly more detrimental for OS (29.5mo; HR 4.12, IC95% 2.6-6.4) than having 1 mutated gene (84.2mo; HR 1.8, IC95% 1.2-2.5) compared with having no mutations (148.9mo). Multivariate analysis results adjusted for IPSS indicated that having two or more mutations was an independent prognostic factor for OS (HR 2.9, 95% CI 1.8-4.5). Notably, the prognostic relevance of harboring two or more mutations involved both lower (low and intermediate-1; HR 1.87, 95% CI 1.3-2.6) and higher (intermediate-2 and high; HR 1.6, 95% CI 1.2-2.1) categories of IPSS. Also LFS resulted significantly shorter (129mo; HR 3.1, 95%CI 1.9-4.8) in MHR+ pts compared with pts with no adverse mutations (323mo). Having 2 or more mutations correlated with greater reduction of LFS (79.6mo; HR 7.02, CI95% 3.9-12.6) than having one mutation only (133.9mo; HR 2.2, IC95% 1.3-3.7) as compared with no mutations (323.2mo). Multivariate analysis showed that IPSS high risk category (HR 4.5; 95% CI 2.3-8.8) and two or more mutated genes (HR 5.3; 95% CI 2.9-9.8) predicted independently for a significant reduction in LFS. The negative impact on LFS of having 2 or more mutated genes compared to one or no mutations was maintained in the lower (HR 6.4, 95% CI 2.6-15.2) and higher (HR 5.5, 95% CI 2.3-12.8) risk categories. Validation cohort Validation cohort included 262 patients (median age 64 years; males = 167) risk stratified by DIPSS-plus into high (n=89, 34%), intermediate-2 (n=92, 35%), intermediate-1 (n=46, 18%) and low (n=34, 13%). One hundred forty-six pts (56%) displayed none of the four aforementioned mutations, 93 (36%) harbored one mutation whereas 23 (9%) harbored two or more mutations. In univariate analysis, having two or more mutations (HR 3.7; 95% CI 2.2-6.1) was significantly more detrimental for OS than having no mutations, which is more favorable than having one mutation (HR 1.9; 95% CI 1.4-2.7). When adjusted for DIPSS-plus, the presence of two or more mutations retained its significance (HR 2.1; 95% CI 1.3-3.6) and outperformed ASXL1 mutation alone in its prognostic relevance Conclusions Overall, these results show that the number of prognostically relevant mutated genes correlate with OS and LFS in pts with PMF, suggesting that screening for these mutations might help to improve risk stratification. Disclosures: No relevant conflicts of interest to declare.

Abstract MAJIC is a phase II trial of Ruxolitinib (RUX) vs Best Available Therapy (BAT) in essential thrombocythemia (ET) patients with resistance/intolerance to Hydroxycarbamide (HC) per European LeukemiaNet (ELN) criteria. Primary outcome was rate of complete hematological response (CHR) within 1 year (ELN criteria); secondary outcomes included partial HR, safety, thrombosis, hemorrhage, progression free survival (including transformation), molecular response (MR), symptom & quality of life (QOL) assessment. We present new data concerning molecular, symptom & clinical responses. Patients were stratified by JAK2V617F status, patient-reported symptoms & QOL determined using EQ5D, MDASI & MPN Symptom Assessment Form (MPN10), & compared using linear mixed models of post-baseline scores through month 12 adjusting for baseline; response was defined as ≥50% reduction in MPN10 total symptom score (TSS). JAK2/CALR/MPL allele burdens were assessed at baseline & 4 monthly. 110 patients were eligible for the modified ITT analysis, 58 (52%) & 52 (48%) in RUX & BAT arms respectively, comprising 44 males, 66 females, mean age 64.2ys, & resistant (24.5%), intolerant (51.8%) or both (22.7%) to HC. CHR was achieved in 27 (46.6%) of RUX patients vs 23 (44.2%) BAT patients (χ2 test p= 0.81). PHR occurred in 26 (44.8%) & 27 (51.9%) of RUX & BAT treated respectively. Grade 3 or 4 anemia occurred in 19% & 0% for RUX arm vs 0% (both grades) for BAT arm, grade 3 or 4 thrombocytopenia in 5.2% & 1.7% of RUX vs 0% (both grades) of BAT patients respectively. Grade 3 or 4 infections occurred in 10.3% of RUX patients vs 3.6% BAT arm. 9 RUX treated patients had 10 thrombotic events & 1 RUX patient a hemorrhage; vs 5 thrombotic & 5 hemorrhagic events in BAT patients (adjusted following central review). Transformations to post-ET MF occurred in 8 RUX vs 3 BAT treated patients, 1 RUX patient developed AML. 2 non-treatment related deaths occurred in each arm. Mean MPN-10 TSS & individual symptoms of early satiety & itching during the first 12 months were all significantly lower for RUX vs BAT (all p<0.05). Patients who achieved CHR had significantly better TSS, fatigue, inactivity, concentration problems, & MDASI symptom interference (all p<0.05) at baseline vs those without; however, scores during treatment did not appear to differ between CHR & non CHR groups after adjusting for these baseline differences. Allele burden during study & MRs (per ELN-IWG criteria Barosi Blood 2013) are shown in Table 1. Assays for JAK2 V617F were performed independently in 3 centres using qPCR (Guy's), TSCA NGS (Oxford) & amplicon-based NGS (Salisbury) & revealed Mean (range): JAK2 (Guy's): 33.2 (0.1-94.6), N=52; JAK2 (Oxford): 38.0 (0.5-92.2), N=52; JAK2 (Sal): 38.3 (0-90.0), N=50 (limited to JAK2 positive only). With Interclass Correlation Coefficient as follows ICC (Guy's v Oxford): 0.92 (95% CI 0.86-0.95) ICC (Guy's v Sal): 0.92 (95% CI 0.86-0.95) ICC (Oxford v Sal): 0.997 (95% CI 0.994-0.998). Notably MRs (n=5) only occurred with RUX treatment. There was no pattern of MR or progression with C/PHR or transformation, but 1 patient who transformed to PET MF had a complete MR. In a separate analysis baseline symptoms & QOL were not associated with JAK2, CALR, nor MPL status. Within RUX, baseline symptoms & QOL did not predict MR; however, fatigue, early satiety & abdominal discomfort (all p<0.05, Table 1) were significantly lower among those with MR vs not during treatment with a descriptively higher symptom response rate (2/4 [50%] vs 9/30 [30%]). Three non pre-specified multivariate analyses were performed to assess baseline factors influencing CHR (modelled for: treatment received, HC resistance or intolerance, white cell count, platelets, Hb & JAK2/CALR status); occurrence of ≥ grade 3 anemia or thrombocytopenia (modelled for: Hb (≥ 100g/dl) JAK2/CALR status); & transformation to PET-MF (modelled for: treatment, Hb ≤100g/dl). Only baseline Hb ≤100g/dl was significant for grade 3+ anemia (OR [95% CI]=0.17 [0.04, 0.72]), & PET-MF only occurred in patients with baseline WBC <10x109/L. This updated analysis shows that HC resistant/intolerant ET is clinically & molecularly diverse. We confirm that these patients are at high risk of thrombosis & transformation as suggested in prior retrospective studies. Molecular responses were limited to RUX & for the first time we demonstrate such responses may correlate with symptom improvement but not always with progression events. Disclosures Harrison: Shire: Honoraria, Speakers Bureau; Gilead: Honoraria, Speakers Bureau; Incyte Corporation: Honoraria, Speakers Bureau; Baxaltra: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Other: travel, accommodations, expenses, Research Funding, Speakers Bureau. Mead:Novartis: Honoraria, Research Funding, Speakers Bureau. Aliman:Novartis: Other: Institutional funding and grant for international conference. . Chen:Novartis: Other: Advisory Board. Coppell:Novartis: Other: Travel, accommodation and conference attendance. Knapper:ONO pharmaceuticals: Research Funding; Novartis: Honoraria, Other: Travel and expenses for international conferences. Ali:Novartis: Honoraria, Other: Conference sponsorship, advisory board meetings. Hamblin:Novartis: Other: Advisory Board. Dueck:Bayer: Honoraria. Cross:Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau. Mesa:Celgene: Research Funding; Promedior: Research Funding; CTI: Research Funding; Gilead: Research Funding; Incyte: Research Funding; Galena: Consultancy; Ariad: Consultancy; Novartis: Consultancy. McMullin:Novartis: Honoraria, Speakers Bureau.

Key Points After hydroxycarbamide therapy in high-risk ET, ruxolitinib showed no improvement for complete or partial response rates compared with BAT. Ruxolitinib significantly improved some disease-related symptoms, but rates of thrombosis, hemorrhage, or transformation were not different.

Abstract Myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPN) are hematologically diverse stem cell malignancies sharing phenotypic features of both myelodysplastic syndromes and myeloproliferative neoplasms. There are currently no standard treatment recommendations for most adult patients with MDS/MPN. To optimize efforts to improve the management and disease outcomes, it is essential to identify meaningful clinical and biologic end points and standardized response criteria for clinical trials. The dual dysplastic and proliferative features in these stem cell malignancies define their uniqueness and challenges. We propose response assessment guidelines to harmonize future clinical trials with the principal objective of establishing suitable treatment algorithms. An international panel comprising laboratory and clinical experts in MDS/MPN was established involving 3 independent academic MDS/MPN workshops (March 2013, December 2013, and June 2014). These recommendations are the result of this collaborative project sponsored by the MDS Foundation.

AbstractImatinib mesylate is effective in the treatment of hematologic malignancies that are characterized by either abl- or PDGFRβ- activating mutations. The drug is also active in a subset of patients with eosinophilic disorders and systemic mast cell disease (SMCD). Recently, a novel tyrosine kinase that is generated from fusion of the Fip1-like 1 (FIP1L1) and PDGFRα (PDGFRA) genes has been identified as a therapeutic target for imatinib mesylate in hypereosinophilic syndrome (HES). We used fluorescence in situ hybridization (FISH) to detect deletion of the CHIC2 locus at 4q12 as a surrogate for the FIP1L1-PDGFRA fusion. CHIC2 deletion was observed in bone marrow cells for 3 of 5 patients with SMCD associated with eosinophilia. Deletion of this locus and expression of the FIP1L1–platelet-derived growth factor receptor α (PDGFRA) fusion was also documented in enriched eosinophils, neutrophils, or mononuclear cells by both FISH and reverse transcriptase–polymerase chain reaction (RT-PCR) for one patient. While all 3 patients with the FIP1L1-PDGFRA rearrangement achieved a sustained complete response with imatinib mesylate therapy, the other two, both carrying the c-kit Asp816 to Val (Asp816Val) mutation, did not. These observations suggest that the FIP1L1-PDGFRA rearrangement occurs in an early hematopoietic progenitor and suggests that the molecular pathogenesis for a subset of SMCD patients is similar to that of HES. Screening for the FIP1L1-PDGFRA rearrangement and Asp816Val mutation will advance rational therapy decisions in SMCD.

Imatinib mesylate (Gleevec), a small molecule inhibitor of abl, kit, and platelet-derived growth factor receptor (PDGFR) tyrosine kinases, has been reported to be effective in the treatment of hypereosinophilic syndrome (HES) and a rare eosinophilia-associated chronic myeloid disorder (eos-CMD) characterized by the t(5;12)(q33;p13) cytogenetic abnormality. In the current study, we sought to confirm the preliminary observations in HES as well as evaluate the therapeutic value of imatinib in eos-CMD that is not associated with t(5;12)(q33;p13). Five patients with HES (all men, median age = 46 years) and 2 with eos-CMD (both men, aged 45 and 58 years) were treated with imatinib at a starting dose of 100 to 400 mg/day. Cytogenetic studies showed no evidence of either the bcr-abl translocation or t(5;12)(q33;p13) in any patient. Screening of exons encoding the intracellular catalytic domains and extracellular ligand binding domains of PDGFRβ (exons 2-23) and c-kit (exons 1-21) in 6 patients demonstrated mostly previously known polymorphisms. At a median follow-up of 17 weeks (range, 10-33 weeks), 2 patients with HES and 1 with eos-CMD have achieved complete clinical remission and 1 additional patient with HES has achieved a partial remission. In contrast to previous observations, all 4 responding patients had elevated serum interleukin-5 levels. Although the drug was well tolerated in most patients, a previously unrecognized treatment toxicity of acute left ventricular dysfunction occurred in a responding patient with HES within the first week of treatment. Myocardial biopsy revealed eosinophilic infiltration and degranulation, and the cardiogenic shock was reversed with the prompt institution of corticosteroid therapy.