Concept: Essential thrombocytosis
Evaluation of Xagrid® Efficacy and Long-term Safety, a Phase IV, prospective, non interventional study performed in 13 European countries enrolled high risk essential thrombocythemia patients treated with cytoreductive therapy. Primary objectives were safety and pregnancy outcomes. Of 3721 registered patients, 3649 received cytoreductive therapy. At registration, 3611 were receiving: anagrelide (Xagrid®) (n=804), other cytoreductive therapy (n=2666), anagrelide + other cytoreductive therapy (n=141). Median age was 56 vs 70 years for anagrelide vs other cytoreductive therapy. Event rates (patients with events/100 patient years) were, for total thrombosis 1.62 vs 2.06, venous thrombosis 0.15 vs 0.53. Anagrelide was more commonly associated with hemorrhage (0.89 vs 0.43), especially with anti-aggregatory therapy (1.35 vs 0.33) and myelofibrosis (1.04 vs 0.30). Other cytoreductive therapies were more associated with acute leukemia (AL) (0.28 vs 0.07) and other malignancies (1.29 vs 0.44). Post-hoc multivariate analyses identified increased risk for thrombosis with prior thrombohemorrhagic events, age ≥65, cardiovascular risk factors, or hypertension. Risk factors for transformation were prior thrombohemorrhagic events, age ≥65, time since diagnosis, and platelet count increase. Safety analysis reflected published data and no new safety concerns for anagrelide were found. Live births occurred in 41/54 pregnancies (76%). (ClinicalTrials.gov #NCT00567502).
Recombinant IFN-α (rIFN-α) induces complete hematologic remissions in patients with myeloproliferative neoplasms (MPNs), but its use has been limited by side effects owing to the relatively high doses used. Now, low-dose rIFN-α is stressed, starting relatively early in the course of the MPNs. In polycythemia vera, this has resulted in a significant clinical, hematologic, morphologic and molecular response manifested by reduction in the JAK2(V617F) allele burden, sustained even after discontinuation of recombinant IFN. In essential thrombocythemia, platelet count reduction is prompt and durable without treatment for varying periods. In hypercellular primary myelofibrosis, rIFN-α has restored normal blood counts, reduced splenomegaly and induced morphologic marrow remissions. This article highlights our current use of rIFN-α in MPNs.
The recent discovery of mutations of the gene calreticulin has allowed raising the proportion of patients with essential thrombocythemia and primary myelofibrosis with known mutational abnormality up to 85-90%. Knowledge of the mechanisms by which mutated calreticulin underlie a myeloproliferative neoplasm as well as the clinical and therapeutic implications is just at the very beginning, and exciting times await research in this field.
Myeloproliferative neoplasms are clonal hematopoietic disorders that manifest as expansion of one or more myeloid lineages. The most common myeloproliferative neoplasms are chronic myeloid leukemia (CML), polycythemia vera, essential thrombocythemia, and primary myelofibrosis. Whereas the genetic basis for CML has been known for more than 30 years, the specific genetic events that contribute to the pathogenesis of polycythemia vera, essential thrombocythemia, and primary myelofibrosis remained unknown until 2005. Our first insight into the molecular cause of these disorders came when the somatic JAK2 V617F mutation(1)-(4) was identified in the majority of patients with polycythemia vera and in a subset . . .
Vascular events represent the most frequent complications of thrombocytemias. We aimed to evaluate their risk in the WHO histologic categories of Essential Thrombocytemia (ET) and early Primary Myelofibrosis (PMF).
Among 248 consecutive patients with blast phase myeloproliferative neoplasm (MPN-BP), DNA collected at the time of blast transformation was available in 75 patients (median age, 66 years; 64% men). MPN-BP followed primary myelofibrosis in 39 patients, essential thrombocythemia in 20 patients, and polycythemia vera in 16 patients. A myeloid neoplasm-relevant 33-gene panel was used for next-generation sequencing. Driver mutation distribution wasJAK257%,CALR20%,MPL9%, and triple-negative 13%. Sixty-four patients (85%) harbored other mutations/variants, including 37% with ≥3 mutations; most frequent wereASXL147%,TET219%,RUNX117%,TP5316%,EZH215%, andSRSF213%; relative mutual exclusivity was expressed byTP53,EZH2,LNK,RUNX1,SRSF2, andNRAS/KRASmutations. Paired chronic-blast phase sample analysis was possible in 19 patients and revealed more frequent blast phase acquisition ofASXL1,EZH2,LNK,TET2,TP53, andPTPN11mutations/variants. In multivariable analysis,RUNX1andPTPN11mutations/variants were associated with shorter survival duration; respective hazard ratios (HRs) (95% confidence interval [CI]) were 2.1 (95% CI, 1.1-3.8) and 3.0 (95% CI, 1.1-6.6). An all-inclusive multivariable analysis confirmed the prognostic relevance ofRUNX1mutations (HR, 1.9; 95% CI, 1.5-5.5) and also showed additional contribution from a treatment strategy that includes transplant or induction of complete or near-complete remission (HR, 0.3; 95% CI, 0.2-0.5). The current study points to specific mutations that might bear pathogenetic relevance for leukemic transformation in MPN and also suggest an adverse survival effect ofRUNX1mutations.
Patients with Ph-negative myeloproliferative neoplasms (MPN), such as polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), are at increased risk for thrombosis/thromboembolism and major bleeding. Due to the morbidity and mortality of these events, antiplatelet and/or anticoagulant agents are commonly employed as primary and/or secondary prophylaxis. On the other hand, disease-related bleeding complications (i.e., from esophageal varices) are common in patients with MPN. This analysis was performed to define the frequency of such events, identify risk factors, and assess antiplatelet/anticoagulant therapy in a cohort of patients with MPN.
Somatic CALR mutations have been identified in the majority of JAK2 mutation-negative essential thrombocythaemia (ET) and primary myelofibrosis. Almost all CALR mutations have been reported to typically generate a +1-base pair (bp) frameshift in the open reading frame. Here, we describe an ET patient with a +2-bp frameshift CALR mutation. A 41-year-old man was admitted because of headache, and diagnosed as JAK2-negative ET. After 4 years, his disease progressed to post-ET myelofibrosis, and CALR mutation analysis demonstrated a +2-bp frameshift CALR mutation caused by two different CALR mutations, c.1139_1151del and c.1211_1215delinsTTGA, on the same allele. The resultant mutant protein sequence shared 19 amino acids with those from type 1 and type 2 CALR mutations, but the downstream C-terminal sequences were different. To our knowledge, CALR double mutations causing +2-bp frameshift are extremely rare. Identification of this novel type of CALR mutation has potential implications for better understanding of CALR oncogenesis. This article is protected by copyright. All rights reserved.
Moderate thrombocytosis can accompany several diseases (bleeding, inflammation, iron deficiency, or autoimmune diseases), but hematologic examination is strongly recommended in a patient with persistent platelet count above 450 G/L unless reactive origin can be confirmed. The 47-year-old woman’s medical history included hypertonia, asthma bronchiale, and endometriosis. In March 2015, she underwent laboratory examination due to weight loss and lack of appetite. Her results showed elevated thrombocyte count (617 G/L), but no iron deficiency. She presented in our clinic on 07. 04. 2015 with acute pain below her left hypochondrial region, but simple imaging examinations showed no difference to explain it. Abdominal CT revealed a 4.5 cm thrombus which protruded into the left renal artery, blocking it. We started APTI- (activated partial thromboplastin time) monitored continuous intravenous treatment with unfractionated heparin. The JAK2V617F mutation analysis came back positive. Subsequent bone marrow examination revealed prefibrotic/early stage myelofibrosis, prompting treatment with hydroxyurea. The applied treatments led to the disappearance of the patient’s symptoms accompanied by the gradual normalisation of the thrombocyte count. Moderate thrombocytosis is often secondary, but if it persists and is accompanied by mainly thromboembolic events, the risk of diseases of the haematopoietic system, primarily Philadelphia chromosome negative chronic myeloproliferative disease should also be considered. Clinically, essential thrombocythaemia and the prefibrotic/early stage of myelofibrosis can be very similar. Differential diagnosis is only possible through the histological examination of the bone marrow, which becomes indispensible due to the difference in prognosis and treatment options. Orv Hetil. 2018; 159(15): 603-609.
Myeloproliferative neoplasms (MPNs) include essential thrombocythemia, polycythemia vera (PV) and primary myelofibrosis (PMF). Phenotype-driver mutations of JAK2, CALR and MPL genes are present in MPNs and can be variably combined with additional mutations. Driver mutations entail a constitutive activation of the JAK2/STAT pathway, the key signaling cascade in MPNs. Among JAK2 inhibitors (JAKis), ruxolitinib (RUX) has been approved for the treatment of intermediate and high risk myelofibrosis (MF) and of PV inadequately controlled by or intolerant of hydroxyurea. Other JAKis, such as fedratinib, pacritinib proved to be useful in MF. The primary endpoints in MF trials were spleen volume response (SVR) and symptom response, whereas in PV trials they were hematocrit control with/without spleen response. In advanced MF, RUX achieved a SVR of more than 35% in around 60% of patients and is long lasting, establishing a new benchmark for MF treatment. RUX efficacy in early MF is also remarkable and toxicity is mild. In PV, hematocrit control was achieved with RUX in approximately 60% of the cases and SVR in 40%. Symptom relief was evident in both conditions. In the long term however, many MF patients lose their SVR. Indeed, the definition of RUX-failure and the design of new trials in this setting are unmet needs. Decrease of hemoglobin/platelet levels and increased infection rates are the most common side effects of RUX, and non-melanoma skin tumors need to be monitored while on treatment. In conclusion, the introduction of JAKis raises the bar of treatment goals in MF and PV.