Chin Yang Li

TET2 mutations and their clinical correlates in polycythemia vera, essential thrombocythemia and myelofibrosis

High-throughput DNA sequence analysis was used to screen for TET2 mutations in bone marrow-derived DNA from 239 patients with BCR-ABL-negative myeloproliferative neoplasms (MPNs). Thirty-two mutations (19 frameshift, 10 nonsense, 3 missense; mostly involving exons 4 and 12) were identified for an overall mutational frequency of ∼13%. Specific diagnoses included polycythemia vera (PV; n=89), essential thrombocythemia (ET; n=57), primary myelofibrosis (PMF; n=60), post-PV MF (n=14), post-ET MF (n=7) and blast phase PV/ET/MF (n=12); the corresponding mutational frequencies were ∼16, 5, 17, 14, 14 and 17% (P=0.50). Mutant TET2 was detected in ∼17 and ∼7% of JAK2V617F-positive and -negative cases, respectively (P=0.04). However, this apparent clustering of the two mutations was accounted for by an independent association between mutant TET2 and advanced age; mutational frequency was ∼23% in patients ⩾60 years old versus ∼4% in younger patients (P<0.0001). The presence of mutant TET2 did not affect survival, leukemic transformation or thrombosis in either PV or PMF; a correlation with hemoglobin <10 g per 100 ml in PMF was noted (P=0.05). We conclude that TET2 mutations occur in both JAK2V617F-positive and -negative MPN, are more prevalent in older patients, display similar frequencies across MPN subcategories and disease stages, and hold limited prognostic relevance.

Systemic mastocytosis in 342 consecutive adults: survival studies and prognostic factors

Clinical phenotype in systemic mastocytosis (SM) is markedly variable, which complicates prognostication and decision making regarding the choice and timing of therapy. In a retrospective study of 342 consecutive adult patients with SM seen at the Mayo Clinic between 1976 and 2007, disease subdesignation according to the World Health Organization (WHO) proposal was indolent (ISM) in 159 (46%), with associated clonal hematologic non-mast cell lineage disease (SM-AHNMD) in 138 (40%), aggressive (ASM) in 41 (12%), and mast cell leukemia in 4 (1%). KITD816V was detected in bone marrow-derived DNA by allele-specific polymerase chain reaction (PCR) in 68% of 165 patients evaluated (ISM, 78%; ASM, 82%; SM-AHNMD, 60%; P = .03); JAK2V617F was detected in 4%, all in SM-AHNMD. Compared with those with nonindolent SM, life expectancy in ISM was superior and not significantly different from that of the age- and sex-matched US population. In addition, multivariable analysis identified advanced age, weight loss, anemia, thrombocytopenia, hypoalbuminemia, and excess bone marrow blasts as independent adverse prognostic factors for survival. The current study validates the prognostic relevance of the WHO subclassification of SM and provides additional information of value in terms of both risk stratification and interpretation of clinical presentation and laboratory results.

The JAK2V617F tyrosine kinase mutation in myelofibrosis with myeloid metaplasia : lineage specificity and clinical correlates

An association between an activating JAK2 mutation (JAK2V617F) and BCR/ABL‐negative myeloproliferative disorders was recently reported in multiple simultaneous publications. In the current study, mutation analysis for JAK2V617F was performed in peripheral blood mononuclear cells (PBMC) from 157 patients with myelofibrosis with myeloid metaplasia (MMM) including 117 with agnogenic (AMM), 22 with postpolycythaemic (PPMM), and 18 with post‐thrombocythaemic (PTMM) myeloid metaplasia. The detection rate for JAK2V617F was significantly higher in PPMM (91%; homozygous in 18%) compared with either AMM (45·3%; homozygous in 2·6%) or PTMM (38·9%; homozygous in 11·1%). Concomitant analysis in granulocytes (n = 57) and CD34+ cells (n = 25) disclosed a higher incidence of homozygous JAK2V617F mutation but the overall mutation rate was similar to that obtained from PBMC. JAK2V617F was not detected in DNA derived from T cells (n = 19). In AMM, the presence of JAK2V617F was associated with an older age at diagnosis and a history of thrombosis or pruritus. Multivariate analysis identified only age and the Dupriez prognostic score as independent prognostic factors; JAK2V617F had no prognostic significance. In conclusion, JAK2V617F is a myeloid lineage‐specific event, its incidence in MMM is significantly higher with an antecedent history of polycythaemia vera (PV), and its presence in AMM does not affect prognosis but is associated with PV‐characteristic clinical features.

Nonhepatosplenic extramedullary hematopoiesis: associated diseases, pathology, clinical course, and treatment.

OBJECTIVE To define associated clinical conditions, pathology, natural history, and treatment outcome of nonhepatosplenic extramedullary hematopoiesis (NHS-EMH). PATIENTS AND METHODS We retrospectively reviewed the medical charts of all patients identified as having NHS-EMH from 1975 to 2002. Diagnosis was made by tissue biopsy, fine-needle aspiration biopsy, or radionuclide bone marrow scanning. RESULTS We identified 27 patients with antemortem diagnosis of NHS-EMH. The most common associated condition and disease site were myelofibrosis with myeloid metaplasia (MMM) (in 18 patients [67%]) and the vertebral column (in 7 patients [26%]; all involving the thoracic region), respectively. At the time of diagnosis of NHS-EMH, concurrent splenic EMH (in 22 patients [82%]; 15 [56%] had undergone splenectomy) and red blood cell transfusion dependency (in 12 patients [44%]) were prevalent. Of the 27 patients, 9 (33%) required no specific therapy. Specific therapy was radiation (in 7 patients with a 71% response rate) and surgical excision (in 6 patients with a 67% response). Treatment-associated complications were limited to surgery. Radiation therapy was not used in the non-MMM group, but low-dose radiation therapy was used in the MMM group for paraspinal or intraspinal EMH (median dose, 1 Gy; range, 1-10 Gy), pleural or pulmonary disease (median dose, 1.25 Gy; range, 1.00-1.50 Gy), and abdominal or pelvic disease (median dose, 2.02 Gy; range, 150-4.50 Gy). Median survival after the diagnosis of NHS-EMH was 13 months in the MMM group and 21 months in the non-MMM group. CONCLUSIONS This retrospective study suggests that NHS-EMH is rare, is often associated with MMM, and preferentially affects the thoracic spinal region. Asymptomatic disease may require no specific treatment, whereas symptomatic disease is best managed with low-dose radiation therapy.

Frequent TET2 mutations in systemic mastocytosis: clinical, KITD816V and FIP1L1-PDGFRA correlates

TET2 (TET oncogene family member 2) is a candidate tumor suppressor gene located at chromosome 4q24, and was recently reported to be mutated in ∼14% of patients with JAK2V617F-positive myeloproliferative neoplasms. We used high-throughput DNA sequence analysis to screen for TET2 mutations in bone marrow-derived DNA from 48 patients with systemic mastocytosis (SM), including 42 who met the 2008 WHO (World Health Organization) diagnostic criteria for SM and 6 with FIP1L1-PDGFRA. Twelve (29%) SM, but no FIP1L1-PDGFRA patients, had TET2 mutations. A total of 17 mutations (13 frameshift, 2 nonsense and 2 missense) were documented in 2 (15%) of 13 indolent SM patients, 2 (40%) of 5 aggressive SM, and 8 (35%) of 23 SM associated with a clonal non-mast cell-lineage hematopoietic disease (P=0.52). KITD816V was detected by PCR sequencing in 50 or 20% of patients with or without TET2 mutation (P=0.05), respectively. Multivariable analysis showed a significant association between the presence of TET2 mutation and monocytosis (P=0.0003) or female sex (P=0.05). The association with monocytosis was also observed in non-indolent SM (n=29), in which the presence of mutant TET2 did not affect survival (P=0.98). We conclude that TET2 mutations are frequent in SM, segregate with KITD816V and influence phenotype without necessarily altering prognosis.

The clinical phenotype of wild-type, heterozygous, and homozygous JAK2V617F in polycythemia vera

Several studies have recently reported on the occurrence of a JAK2V617F mutation in myeloid cells from the majority of patients with polycythemia vera (PV). The clinical relevance of this novel observation currently is under study.

Cytogenetic findings and their clinical relevance in myelofibrosis with myeloid metaplasia.

The prognostic significance of bone marrow cytogenetic lesions in myelofibrosis with myeloid metaplasia (MMM) was investigated in a retrospective series of 165 patients. An abnormal karyotype was demonstrated in 57% of patients. At diagnosis (n = 92), 48% of the patients had detectable cytogenetic abnormalities, and clonal evolution was frequently demonstrated in sequential studies. More than 90% of the anomalies were represented by 20q–, 13q–, +8, +9, 12p–, and abnormalities of chromosomes 1 and 7. Of these, 20q–, 13q– and +8 were the most frequent sole abnormalities, each occurring in 15–25% of the abnormal cases. Trisomy 9 and abnormalities of chromosomes 1 and 7 were equally prevalent but were usually associated with additional cytogenetic lesions. Chromosome 5 abnormalities were infrequent but were over‐represented in the group of patients exposed to genotoxic therapy. In a multivariate analysis that incorporated other clinical and laboratory variables, the presence of an abnormal karyotype did not carry an adverse prognosis. Instead, +8, 12p–, advanced age and anaemia were independent prognostic determinants of inferior survival. In particular, survival was not adversely affected by the presence of either 20q– or 13q–.

Hematological manifestations of copper deficiency: a retrospective review

Copper deficiency is an established cause of hematological abnormalities but is frequently misdiagnosed. Copper deficiency can present as a combination of hematological and neurological abnormalities and it may masquerade as a myelodysplastic syndrome. We reviewed the records of patients with hypocupremia and hematologic abnormalities identified between 1970 and 2005. Patients with hypocupremia unrelated to copper deficiency (e.g. Wilson’s disease) were excluded. Forty patients with copper deficiency and hematological abnormalities were identified. Ten patients (25%) had undergone bariatric (weight reduction) surgery and an additional 14 patients (35%) had undergone surgery on the gastrointestinal tract, most commonly gastric resection. In 12 cases, no cause for copper deficiency was identified. Anemia and neutropenia were the most common hematologic abnormalities identified and the majority of the patients also had neurologic findings, most commonly due to myeloneuropathy. Abnormalities observed on bone marrow examination including vacuoles in myeloid precursors, iron‐containing plasma cells, a decrease in granulocyte precursors and ring sideroblasts may be valuable clues to the diagnosis. Copper deficiency is an uncommon but very treatable cause of hematologic abnormalities.

Thalidomide treatment in myelofibrosis with myeloid metaplasia

Summary.  Myelofibrosis with myeloid metaplasia (MMM) is uniquely characterized by macroscopic bone marrow stromal changes that are believed to be both reactive and cytokine mediated. Furthermore, a prognostically detrimental increase in bone marrow angiogenesis has recently been demonstrated. These observations suggest a potential therapeutic role for agents that are inhibitory to angiogenesis as well as cytokines that are pathogenetically implicated in MMM. In a prospective study of 15 patients with MMM, thalidomide treatment, starting at a dose of 200 mg/d, resulted in increased platelet counts (12 of 15 patients), increased haemoglobin level (3 of 15), a modest decrease in spleen size (3 of 12), increased bone marrow megakaryopoiesis (5 of 9) and decreased bone marrow angiogenesis (2 of 9). Undesirable haematological effects included pericardial extramedullary haematopoiesis in one patient, marked leucocytosis in two patients and extreme thrombocytosis in three patients. The thrombocytosis occurred in both patients with post‐thrombocythaemic myeloid metaplasia (PTMM) and was also associated with higher baseline levels of circulating CD34+ cells. Previously described toxicities of thalidomide were seen in the majority of patients and dose escalation to 400 mg/d was permitted in only two patients. In contrast, toxicity‐related dose reductions to 50 mg/d did not appear to lessen drug efficacy. We conclude that thalidomide has both beneficial and potentially adverse biological activity in MMM. A lower dose of the drug might be more tolerable without compromising therapeutic value. Patients with PTMM and/or markedly increased circulating CD34+ cell counts might be susceptible to thalidomide‐induced thrombocytosis.

Leucocytosis in polycythaemia vera predicts both inferior survival and leukaemic transformation

Leucocytosis (leucocyte count >15 × 109/l) was recently associated with thrombosis in polycythaemia vera (PV). This study sought the prognostic relevance of leucocytosis for survival and leukaemic or fibrotic transformation. Amongst 459 patients with PV seen at our institution in recent years (median age, 60 years; 56% males), 146 deaths and 88 leukaemic (n = 34) or fibrotic (n = 54) transformations were documented. Arterial or venous thrombosis occurred in 14% and 9% of patients at diagnosis and in 25% and 15% during follow‐up, respectively. Multivariate analysis identified the advanced age (P < 0·0001), leucocytosis (leucocyte count ≥15 × 109/l; P = 0·0006) and arterial thrombosis at diagnosis (P = 0·01) as independent predictors of inferior survival. In the absence of the first two risk factors, median survival was projected at 272 months as opposed to 108 months in the presence of both risk factors (P < 0·0001). Leucocytosis was also identified as an independent predictor of both leukaemic transformation and venous thrombosis during follow‐up. Time‐to‐event analysis did not disclose a significant association between single or multiple cytotoxic drug exposure and either leukaemic or fibrotic transformation. The current study highlighted the prognostic relevance of leucocytosis on various aspects of the disease in PV.