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M. Schino et al.
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Figure 2. Kaplan-Meier curves for progression-free survival of polycythemia vera and of early/prefibrotic primary myelofibrosis patients. (A) Kaplan-Meier curve for progression-free survival (PFS) of polycythemia vera (PV) patients stratified by megakaryocytic activation (M-ACT); (B) Kaplan-Meier curve for PFS of early/prefibrotic primary myelofibrosis (PMF) patients by M-ACT. M-ACT positive patients (red-line) was significantly associated to a worse PFS (P<0.0001) with respect to those with- out M-ACT (blue-line) in both groups.
(P=0.1024) and A/V thrombosis (P=0.4216) did not show significant correlation with PFS.
Multivariate analysis of PFS, including M-ACT status, JAK2 status, WBC count and history of major bleeding, showed that the presence of M-ACT and the JAK2 V617F allele burden were the only significant predictors (for M-ACT status, P<0.0001, HR 10.4180, 95% CI: 4.0978- 26.4858; for JAK2 V617F allele burden ≥50%, P=0.0105, HR 0.0105, 95% CI: 1.2855-6.6460; Table 3).
Megakaryocytic activation in non-polycythemia vera myeloproliferative neoplasm cohort
One hundred and nine of 199 early/prefibrotic PMF patients did not meet histological criteria for M-ACT
(55%) versus 90 who did (45%). In this cohort, M-ACT showed a strong correlation with clinical parameters, such as palpable splenomegaly (P=0.001) and history of major bleeding (P=0.001), and with hematologic parameters, like platelet count (P=0.0001), LDH serum levels (P=0.003), WBC count (P=0.002), presence of CALR mutations (P=0.001; Table 2). Notably, we found a significant associ- ation between M-ACT and CALR type 1 mutation (P=0.0001) while we did not find a significant correlation between M-ACT and CALR type 2 mutation (P=1.0). We found a significant yet milder correlation with sex, with M-ACT being more prevalent in females (P=0.05), and with JAK2 V617F allele burden≥50% (P=0.04). On the contrary, no significant correlation was found between
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