Chiasakul, Thita

Myeloproliferative neoplasm (MPN) patients are at risk of splanchnic vein thromboses (SVT). Prior studies have failed to demonstrate a benefit of hydroxyurea therapy in preventing recurrent thrombosis after SVT, but are limited by small sample sizes and inability to account for starting, stopping, or switching of cytoreductive therapies. To better assess the impact of cytoreductive therapy on thrombosis recurrence, we performed a retrospective cohort study of MPN-SVT patients from the international GASTRO-MPN Consortium, treating cytoreductive therapy as a time-dependent covariate. We identified 757 patients, of which 43% were treated with cytoreductive therapy. During a median follow-up of 7.4 years, 256 patients (34%) had thrombosis recurrence; 145 (19%) had SVT extension/recurrence/TIPS thrombosis, 138 (18%) an thrombosis recurrence outside the splanchnic bed (74% were venous). Additionally, 262 patients (35%) experienced clinically relevant bleeding and 170 (22%) died. After adjusting for age, sex, prior thrombosis, timing of MPN diagnosis relative to SVT, anticoagulation initiation within 30 days of SVT diagnosis, MPN type, JAK2 status, other cancers and cirrhosis, cytoreductive therapy was associated with a decreased risk of recurrent thrombosis (HR 0.67 95%CI 0.50-0.89, p=0.01). This was driven by a lower risk of SVT extension/recurrence (HR 0.62 95%CI 0.42-0.90, p=0.01) but not by extra-splanchnic thrombosis recurrence (HR 0.97 95%CI 0.72-1.30, p=0.82). In a subgroup of patients without erythrocytosis/thrombocytosis at initial SVT (n=275), cytoreductive therapy was associated with a HR 0.65 (95%CI 0.40-1.07, p=0.09) for recurrent thrombosis. These data support the use of cytoreductive therapy in MPN-SVT patients to prevent recurrent thrombosis, particularly SVT extension/recurrence.

Abstract Background Patients with myeloproliferative neoplasms (MPNs) are at risk of splanchnic vein thrombosis (SVT). Prior studies failed to demonstrate a benefit of hydroxyurea in preventing SVT extension/recurrence, but these were limited by small sample sizes and inability to account for starting, stopping, or switching of cytoreductive therapies. We therefore investigated the role of cytoreduction as a time-dependent covariate on thrombosis recurrence in a large, international cohort of MPN-SVT patients. Methods We performed a retrospective cohort study of MPN-SVT patients included in the international GASTRO-MPN consortium. Patients diagnosed with MPN at any time before, concurrently with, or up to 60 days after initial SVT were included. Primary outcome was time from initial SVT to first thrombosis recurrence, defined as the composite of SVT extension/recurrence, transjugular intrahepatic portosystemic shunt (TIPS) thrombosis, or venous/arterial thrombosis outside the splanchnic veins. Secondary outcomes included SVT extension/recurrence, TIPS thrombosis or extra-SVT thrombosis individually, clinically relevant bleeding (composite of major and clinically relevant non-major bleeding), MPN progression to myelofibrosis or blast phase, and death. Cytoreductive therapy was treated as a time-dependent covariate to account for discontinuation and therapy changes. Multivariable Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CI). Results A total of 757 patients were included for this analysis. Median age was 51 years (IQR 38-62), 59% were female. SVT involved the portomesenteric veins in 558 (77%) patients, hepatic veins in 95 (13%), and both in 54 (7.4%). MPN was known prior to initial SVT in 316 patients (42%) and diagnosed concurrently or up to 60 days after SVT in 441 (58%). Polycythemia vera (PV) was the most common MPN subtype (43%), followed by essential thrombocythemia (ET) in 24%, and primary myelofibrosis in 14%. JAK2V617F mutation was present in 86% and CALR in 2.9%. 13% had prior non-SVT thrombosis. 607 patients (83%) were treated with cytoreduction. At time of SVT, 131 patients (17%) were already on cytoreduction; in those who started after SVT, median time to initiation was 54 days after SVT, and median duration of cytoreduction per patient was 63 months. Cytoreductive therapies used at any point in treatment included hydroxyurea in 504 (69%), ruxolitinib in 182 (25%), and interferon-based in 85 (12%) patients. Anticoagulation (AC) was started within 30 days after SVT in 504 (68%) patients. Median duration of any AC per patient was 24.6 months. During a median follow up of 7.4 years, 245 patients (33%) had thrombosis recurrence; 143 (20%) had SVT extension/recurrence/TIPS thrombosis, 129 (18%) extra-SVT thrombosis (of which 74% venous), 237 patients (32%) experienced clinically relevant bleeding, and 163 (22%) died. After adjusting for age, sex, timing of MPN diagnosis relative to SVT diagnosis, AC within 30 days of SVT, PV/ET vs other MPN, JAK2 mutation, previous thrombosis, non-MPN cancer, and cirrhosis, cytoreductive therapy was associated with a significantly decreased risk of recurrent thrombosis (HR 0.67 95%CI 0.50-0.89, p=0.01). Age was associated with an increased risk of recurrent thrombosis (p=0.01). When considering types of recurrent thrombosis, cytoreduction was associated with a decreased risk of SVT extension/recurrence/TIPS thrombosis (HR 0.62 95%CI 0.42-0.90, p=0.01), but not thrombosis outside the splanchnic veins (HR 0.97 95%CI 0.72-1.30, p=0.82). There was no association between cytoreduction and bleeding (HR 1.10 95%CI 0.82-1.47, p=0.52). Similarly, there was no association between cytoreduction and time to MPN progression (p=0.24) or overall survival (p=0.30). In a subgroup of patients without erythrocytosis/thrombocytosis at initial SVT (n=271), cytoreductive therapy was associated with a HR 0.65 (95%CI 0.40-1.10, p=0.09) for recurrent thrombosis. Limited sample size and low event-rate precluded evaluation of the impact of individual cytoreductive therapies. Conclusions In the largest cohort of MPN-SVT patients to date, we show for the first time that cytoreductive therapy is associated with a decreased risk of thrombosis recurrence, driven largely by decreased SVT extension/recurrence/TIPS thrombosis. Collectively, these findings support use of cytoreductive therapy in individuals with MPN-SVT to prevent recurrent thrombosis.

Background: Myeloproliferative neoplasms (MPNs) are chronic leukemias with increased thrombotic risk. Venous thrombosis in MPN often occurs in atypical sites, such as splanchnic vein thrombosis (SVT), defined by thrombosis in the portal, hepatic, mesenteric, or splenic veins. Data to guide anticoagulation management of SVT in MPN patients is lacking. Objectives: The purpose of this study is to evaluate outcomes as well as the safety and efficacy of different anticoagulation strategies in MPN patients with SVT. Methods: A retrospective cohort study of MPN patients with SVT from 10 international centers was conducted. All centers performed systematic identification of adults with a World Health Organization 2016 diagnosis of an MPN (polycythemia vera [PV], essential thrombocythemia [ET], myelofibrosis [MF], prefibrotic MF, MPN-unclassifiable [MPN-U]) and confirmed SVT. Inclusion criteria were met if first SVT occurred after or within one year before MPN was diagnosed. The primary outcome was 1-year cumulative incidence of recurrent venous (VT) or arterial thrombosis (AT). Secondary outcomes included 1-year cumulative incidence of (1) major and clinically relevant non-major bleeding (CRNMB) by International Society on Thrombosis and Hemostasis criteria, (2) SVT recanalization; and (3) 1-year overall survival. Death as a competing risk was used for cumulative incidence analyses of recurrence and bleeding. Results: 486 MPN patients (median age at first SVT 51 years; 62.3% female) were identified. MPN diagnosis preceded SVT in 35.2% of patients (median time 4.8 years) and occurred simultaneously or within 1 year of first SVT in 64.8% of patients. 43.8% of patients had PV, 23.7% ET, 14.2% MF, 3.1% prefibrotic MF and 13.2% MPN-U. The most common driver mutation was in JAK2 (90.7%) followed by CALR (4.4%) and MPL (1.6%). SVT localization was isolated to portal (25.7%), hepatic (15.4%), mesenteric (1.9%), and splenic veins (4.3%), and in 51.2% of cases SVT occurred in multiple vessels. Prior VT or AT occurred in 8.8% and 4.1% of subjects, respectively. Cytoreduction (most commonly hydroxyurea [36.9%], interferon [9.6%] or JAK inhibitor [6.8%]) was started after SVT in 58.7% of newly diagnosed MPN patients and 40.6% of those with known MPN. 57.6% of patients were anticoagulated, 3.5% of patients were treated with an antiplatelet agent, and 11.7% were treated with both. The most common initial anticoagulants were vitamin K antagonists (VKA) (29.2%), direct oral anticoagulants (DOAC; 20.4%), and low-molecular-weight heparin (LMWH; 10.5%). DOACs were more commonly used in the USA and Asia than Europe (21.2%, 52%, and 13.5%; p<0.001). The median duration of anticoagulation was 23.9 months, with 62.8% still on anticoagulation after 3 years or at last follow-up. 1-year cumulative incidence of recurrent VT and AT was 14% (95% CI 11-18) (5.8% for recurrent SVT [95% CI 3.9-8.3]; 6.3% for other VT [95% CI 4.3-8.8]; 2.4% for AT [95% CI 1.3-4.2]), with an overall time to event 89 (IQR 34-193) days. Thrombosis incidence was similar in patients initially treated with VKA (13%), DOAC (15%) or LMWH (16%) (p=0.93); in comparison, individuals not treated with anticoagulation had 1-year thrombosis incidence of 13% (p=0.22). 1-year major and CRNMB cumulative incidence in all patients was 5.8% (95% CI 3.9-8.2) and 8.5% (95% CI 6.1-11), with median time to event 68 (IQR 13-150) days. Incidence of major bleeding was similar in VKA, DOAC, and LMWH-treated patients (5.9%, 6.6%, and 4.0%; p=0.89). 1-year cumulative incidence of SVT (partial) recanalization was 13% (95% CI 9.8-16) in all patients, with a median time to recanalization of 127 (IQR 40-323) days; recanalization rates were similar in anticoagulated and non-anticoagulated patients (p=0.76). There was a trend toward higher recanalization rates in patients treated with DOAC (26.9%) than with VKA (21.5%) or LMWH (13.6%; p=0.28). 1-year overall survival was 94.2% (95% CI 91.8-96.1) and similar between treatment groups (VKA 96.7%, DOAC 95.6%, LMWH 89.7%; p=0.11) and for no anticoagulation (82.3%; p=0.32). Conclusions: This is the largest contemporary cohort of MPN patients with SVT. MPN patients with SVT remain at risk for short-term thrombosis and bleeding complications regardless of treatment. We found no significant differences in outcomes between anticoagulation strategies, including in patients treated with DOACs compared to VKA or LMWH.