ABSTRACT
A quarter of patients with essential thrombocythemia or primary myelofibrosis carry a driver mutation of CALR, the calreticulin gene. A 52-bp deletion (type 1) and a 5-bp insertion (type 2 mutation) are the most frequent variants. These indels might differentially impair the calcium binding activity of mutant calreticulin. We studied the relationship between mutation subtype and biological/clinical features of the disease. Thirty-two different types of CALR variants were identified in 311 patients. Based on their predicted effect on calreticulin C-terminal, mutations were classified as: (i) type 1-like (65%); (ii) type 2-like (32%); and (iii) other types (3%). Corresponding CALR mutants had significantly different estimated isoelectric points. Patients with type 1 mutation, but not those with type 2, showed abnormal cytosolic calcium signals in cultured megakaryocytes. Type 1-like mutations were mainly associated with a myelofibrosis phenotype and a significantly higher risk of myelofibrotic transformation in essential thrombocythemia. Type 2-like CALR mutations were preferentially associated with an essential thrombocythemia phenotype, low risk of thrombosis despite very-high platelet counts and indolent clinical course. Thus, mutation subtype contributes to determining clinical phenotype and outcomes in CALR-mutant myeloproliferative neoplasms. CALR variants that markedly impair the calcium binding activity of mutant calreticulin are mainly associated with a myelofibrosis phenotype.
Subject(s)
Calreticulin/genetics , Mutation , Primary Myelofibrosis/genetics , Thrombocythemia, Essential/genetics , Adolescent , Adult , Aged , Aged, 80 and over , Calcium/metabolism , Cells, Cultured , Exons , Female , Humans , Isoelectric Point , Male , Megakaryocytes/metabolism , Middle Aged , Primary Myelofibrosis/metabolism , Thrombocythemia, Essential/metabolismABSTRACT
BACKGROUND: Tumor regression after antiviral therapy (AT) is in favor of an etiological role of hepatitis C virus (HCV) in non-Hodgkin's B-cell lymphomas (NHL). PATIENTS AND METHODS: We carried out a cohort study of 704 consecutive HIV-negative, HCV-positive patients with indolent NHL diagnosed and treated from 1993 to 2009 in 39 centers of the Fondazione Italiana Linfomi; 134 patients were managed with AT for lymphoma control. RESULTS: For entire cohort, 5-year overall survival (OS) was 78% [95% confidence interval (CI): 74%-82%] and 5-year progression-free survival (PFS) was 48% (95% CI: 44%-53%). In multivariate analysis, the use of AT during the patients' life had positive impact on OS. Forty-four of the 100 patients treated with first-line AT achieved a complete remission (CR) and 33 a partial response (PR). HCV-RNA clearance was achieved in 80 patients and was related to lymphoma response. At a median follow-up of 3.6 years, 5-year PFS was 63% (95% CI: 50%-73%). CR + PR rate was 85% with AT as second-line treatment. CONCLUSION: AT produces HCV-RNA clearance and consequent tumor regression in most patients with HCV-related indolent NHL. AT used at any time is associated with improved OS. Consequently, AT can be considered an option for patients with indolent lymphomas who do not need immediate cytoreductive treatment.
