Impact of Pre-Graft Ruxolitinib on Post-Transplantation Outcome in Myelofibrosis Patients

Background: Allogeneic hematopoietic stem cell transplantation (HSCT) remains the only curative therapy in patients with primary or secondary myelofibrosis. Ruxolitinib, a JAK-inhibitor, has been approved in myelofibrosis patients and is effective to alleviate symptoms of the disease in a substantial proportion of patients. In a French phase 2 study, the use of ruxolitinib as a bridge to HSCT was followed by a high transplantation rate, with one third of patients presenting clinical improvement before HSCT (partial response or spleen size reduction) (BMT 2021, Robin et al). The aim of the current study is to compare post-transplantation outcomes between patients who received ruxolitinib before HSCT and those who did not. Methods: This retrospective study includes patients with primary or secondary myelofibrosis registered in the SFGM-TC registry including patients from France, Belgium and Switzerland. Patients who received HSCT between July 2010 and December 2019 with available information regarding ruxolitinib treatment were included. The impact of ruxolitinib was analyzed by multivariable Cox regression and a propensity score. Results: 305 patients could be included, of whom 143 received ruxolitinib prior to HSCT (RuxoG). All patient characteristics are given in RuxoG followed by no ruxolitinib group (noRuxo). The diagnosis before HSCT was primary myelofibrosis (83% vs 75%), secondary myelofibrosis (13% vs 19%) or transformed into AML (4% vs 6%). Karnofsky score at transplant was < 70% in 9% and 11%. In RuxoG. median age was older (60.29 vs. 58.75, p=0.069) and delay from diagnosis longer (20.42 vs 13.26 months, p=0.040). RuxoG patients had less frequently anemia < 10 g/dl (84% vs 98%, p=0.027) or thrombocytopenia < 50 G/L (22% vs 32%, p=0.066) and presented more frequently splenomegaly or pre-graft splenectomy (83% vs 63%, p=0.0007). DIPSS score was well balanced in both groups, being high or intermediate-2 in 100 patients (79% vs 86%, p=0.23), from the 235 patients with available data. Myeloablative conditioning regimen was used in 16% vs 26% (p=0.049), and conditioning regimen consisted of on fludarabine-busulfan in 33% vs 61%, fludarabine-melphalan in 47% vs 22% or other in 20% vs 16% (p<0.0001). The donor was HLA-matched in 93% and 85%, with 31% vs 35% being matched sibling donor. Partial response or any other response before HSCT was reported in 41% (RuxoG) and 29% (noRuxo). Regarding post-transplant outcomes, cumulative incidence of grade 2-4 or 3-4 acute GVHD at day 100 was 46.5% and 32.2% in RuxoG and 40.4% and 20.7% in noRuxo group (p=0.11 and p=0.023, respectively). Chronic GVHD incidence at 24 months was 33.2% in RuxoG and 43.3% in noRuxo group (p=0.15) Overall survival was improved for noRuxo versus RuxoG, with 60 month OS at 40.3% and 57.0% (p=0.0067) (Figure 1). Causes of death were: HSCT related in 35 and 41 patients, related to GVHD in 65% and 43%, respectively. A multivariate Cox full model after selection and imputation showed that prior ruxolitinib significantly increased the risk of mortality (Table 1). Age, conditioning regimen, thrombocytopenia, performance status and type of donor were also prognostic. The propensity score confirmed that prior ruxolitinib was associated with higher risk of mortality (HR: 1.60, [95%CI:1.06 to 2.42]; p=0.024) including after adjustment for the delay from diagnosis to transplantation (HR: 1.59 [95%CI: 1.05 to 2.42], p=0.028). Of note, in patients responding to prior ruxolitinib, this deleterious effect was not observed. Conclusion: Patients who received ruxolitinib before HSCT were at higher risk of acute GVHD and post-transplant mortality, but this was not observed in patients responding to ruxolitinib and it does not translate into higher risk of chronic GVHD. Main hypotheses to explain these finding could be: 1) specific disease, patient or transplant characteristics in RuxoG; 2) the longer delay to transplantation or 3) a specific effect of ruxolitinib. This study suggests that myelofibrosis patients responding to ruxolitinib should have the transplant without waiting disease progression. Figure 1 Figure 1. Disclosures Forcade: Novartis: Other: travel grant. Loschi: AbbVie: Ended employment in the past 24 months, Honoraria; CELGENE/BMS: Honoraria; Gilead: Ended employment in the past 24 months, Honoraria; Novartis: Ended employment in the past 24 months, Honoraria; Servier: Ended employment in the past 24 months, Honoraria; MSD: Honoraria. Duléry: Takeda Gilead Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Robin: NEOVII MEDAC NOVARTIS: Research Funding.

Pulmonary Hypertension Is Associated with Poor Outcomes in Patients with Myeloproliferative Neoplasms and Cardiovascular Disease

Background: Myeloproliferative neoplasms (MPNs) are a group of disorders of clonal hematopoiesis and include essential thrombocythemia (ET), polycythemia vera (PV) and primary myelofibrosis (PMF). Cardiovascular disease, including atrial fibrillation (AF), heart failure (HF), pulmonary hypertension (PH), and atherosclerotic heart disease, is an underappreciated cause of morbidity and mortality in MPNs. Additionally, MPNs harbor mutations commonly seen in clonal hematopoiesis of indeterminate potential (CHIP) which has been shown to be associated with increased cardiovascular risk. PH has been associated with MPN and MPN-associated PH is classified as group 5 PH according to the World Health Organization. Although studies have shown PH to occur in between 3.8% to 58% of patients with PMF and has been associated with decreased overall survival in PV, its impact on cardiovascular prognosis, including cardiovascular death (CV death), in patients with MPN has been understudied. Our study aims to investigate the prognostic implication of PH in a high risk MPN population, those with cardiovascular disease. Methods: Our study is a single center retrospective cohort study. Using an institutional database, we identified 197 patients with MPN (ET, PV or PMF) who had cardiovascular disease (AF, hospitalization for HF or acute coronary syndrome after MPN diagnosis) and had undergone right heart catheterization (RHC) or transthoracic echocardiography (TTE). PH was defined as either a mean pulmonary artery pressure ≥ 20 mmHg on RHC or estimated right ventricular systolic pressure (RVSP) ≥ 50 mmHg on TTE. Our primary outcome was CV death (death due to pulmonary embolism, myocardial infarction, stroke, arrhythmia, sudden death or HF). Other outcomes of interest included all-cause mortality, HF hospitalization, VTE and arterial thrombosis. Continuous variables were compared using Student's t-test, categorical variables and outcomes were compared with the Fisher exact test. We used a Fine-Gray model to determine the effect of PH on CV death using other causes of death as competing events. To investigate the effect of PH on our outcomes we also used a multivariable logistic regression model using age, sex, MPN type, MPN treatment, arterial and venous thrombosis prior to and after MPN diagnosis, diabetes, prior HF diagnosis, HF hospitalization after MPN diagnosis, AF, hyperlipidemia, leukemic or secondary myelofibrosis transformation, and diabetes as co-variables. Results: There were 92 patients with PH and 105 patients without PH. Median age at MPN diagnosis was higher in PH vs non-PH patients (73 vs 71, p = 0.038). The median time to diagnosis of PH from MPN diagnosis was 69 months (IQR 43, 113). Patients with PH had higher rates of prior HF (54% vs 32%, p = 0.001) and hypertension (83% vs 64%, p = 0.004), but lower rates of AF (64% vs 79%, p = 0.026) compared with patients without PH. MPN types and driver mutations were not statistically significant between PH and non-PH groups. More patients with PH had leukemic or secondary myelofibrosis transformation compared with patients without PH (23% vs 11%, p = 0.037). Patients with PH had higher rates of CV death (35% vs 9%, p < 0.0001), all-cause death (58% vs 37%, p = 0.004), HF hospitalization (73% vs 36%, p < 0.0001) and VTE (25% vs 12%, p = 0.027) but not arterial thrombosis (39% vs 41%, p = 0.88). Cumulative incidence of CV death was higher in PH compared with non-PH patients (Figure 1A, Fine-Gray HR 5.53, 95% CI 2.58-11.85). After multivariable regression, PH was associated with higher odds of CV death (Figure 1B, aOR 6.1, 95% CI 2.2-19.0), VTE (aOR 3.3, 95% CI 2.0-25.5), HF hospitalization (aOR 3.9, 95% CI 1.6-10.2) but not all-cause death (aOR 1.5, 95% CI 0.7-3.2) or arterial thrombosis (aOR 0.9, 95% CI 0.4-1.9), Figure 1B. Conclusions: In patients with MPN and cardiovascular diseases, PH is associated with worse outcomes including CV death, VTE, HF hospitalization and leukemic/secondary myelofibrosis transformation compared with patients without PH. More investigation is needed but our results suggests early screening for PH may be beneficial in this patient population. Figure 1 Figure 1. Disclosures Neuberg: Madrigal Pharmaceuticals: Other: Stock ownership; Pharmacyclics: Research Funding. Rosovsky: Janssen: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Inari: Consultancy, Membership on an entity's Board of Directors or advisory committees; Dova: Consultancy, Membership on an entity's Board of Directors or advisory committees. Hobbs: Bayer: Research Funding; Incyte Corporation: Research Funding; Merck: Research Funding; Constellation Pharmaceuticals: Consultancy, Research Funding; Novartis: Consultancy; Celgene/Bristol Myers Squibb: Consultancy; AbbVie.: Consultancy.

Cell-autonomous megakaryopoiesis associated with polyclonal hematopoiesis in triple-negative essential thrombocythemia

A subset of essential thrombocythemia (ET) cases are negative for disease-defining mutations on JAK2, MPL, and CALR and defined as triple negative (TN). The lack of recurrent mutations in TN-ET patients makes its pathogenesis ambiguous. Here, we screened 483 patients with suspected ET in a single institution, centrally reviewed bone marrow specimens, and identified 23 TN-ET patients. Analysis of clinical records revealed that TN-ET patients were mostly young female, without a history of thrombosis or progression to secondary myelofibrosis and leukemia. Sequencing analysis and human androgen receptor assays revealed that the majority of TN-ET patients exhibited polyclonal hematopoiesis, suggesting a possibility of reactive thrombocytosis in TN-ET. However, the serum levels of thrombopoietin (TPO) and interleukin-6 in TN-ET patients were not significantly different from those in ET patients with canonical mutations and healthy individuals. Rather, CD34-positive cells from TN-ET patients showed a capacity to form megakaryocytic colonies, even in the absence of TPO. No signs of thrombocytosis were observed before TN-ET development, denying the possibility of hereditary thrombocytosis in TN-ET. Overall, these findings indicate that TN-ET is a distinctive disease entity associated with polyclonal hematopoiesis and is paradoxically caused by hematopoietic stem cells harboring a capacity for cell-autonomous megakaryopoiesis.

Inflammatory Pathophysiology as a Contributor to Myeloproliferative Neoplasms

Myeloid neoplasms, including acute myeloid leukemia (AML), myeloproliferative neoplasms (MPNs), and myelodysplastic syndromes (MDS), feature clonal dominance and remodeling of the bone marrow niche in a manner that promotes malignant over non-malignant hematopoiesis. This take-over of hematopoiesis by the malignant clone is hypothesized to include hyperactivation of inflammatory signaling and overproduction of inflammatory cytokines. In the Ph-negative MPNs, inflammatory cytokines are considered to be responsible for a highly deleterious pathophysiologic process: the phenotypic transformation of polycythemia vera (PV) or essential thrombocythemia (ET) to secondary myelofibrosis (MF), and the equivalent emergence of primary myelofibrosis (PMF). Bone marrow fibrosis itself is thought to be mediated heavily by the cytokine TGF-β, and possibly other cytokines produced as a result of hyperactivated JAK2 kinase in the malignant clone. MF also features extramedullary hematopoiesis and progression to bone marrow failure, both of which may be mediated in part by responses to cytokines. In MF, elevated levels of individual cytokines in plasma are adverse prognostic indicators: elevated IL-8/CXCL8, in particular, predicts risk of transformation of MF to secondary AML (sAML). Tumor necrosis factor (TNF, also known as TNFα), may underlie malignant clonal dominance, based on results from mouse models. Human PV and ET, as well as MF, harbor overproduction of multiple cytokines, above what is observed in normal aging, which can lead to cellular signaling abnormalities separate from those directly mediated by hyperactivated JAK2 or MPL kinases. Evidence that NFκB pathway signaling is frequently hyperactivated in a pan-hematopoietic pattern in MPNs, including in cells outside the malignant clone, emphasizes that MPNs are pan-hematopoietic diseases, which remodel the bone marrow milieu to favor persistence of the malignancy. Clinical evidence that JAK2 inhibition by ruxolitinib in MF neither reliably reduces malignant clonal burden nor eliminates cytokine elevations, suggests targeting cytokine mediated signaling as a therapeutic strategy, which is being pursued in new clinical trials. Greater knowledge of inflammatory pathophysiology in MPNs can therefore contribute to the development of more effective therapy.