The Latin American experience of allografting patients with severe aplastic anaemia: real-world data on the impact of stem cell source and ATG administration in HLA-identical sibling transplants.

We studied 298 patients with severe aplastic anaemia (SAA) allografted in four Latin American countries. The source of cells was bone marrow (BM) in 94 patients and PBSCs in 204 patients. Engraftment failed in 8.1% of recipients with no difference between BM and PBSCs (P=0.08). Incidence of acute GvHD (aGvHD) for BM and PBSCs was 30% vs 32% (P=0.18), and for grades III-IV was 2.6% vs 11.6% (P=0.01). Chronic GvHD (cGvHD) between BM and PBSCs was 37% vs 59% (P=0.002) and extensive 5% vs 23.6% (P=0.01). OS was 74% vs 76% for BM vs PBSCs (P=0.95). Event-free survival was superior in patients conditioned with anti-thymocyte globulin (ATG)-based regimens compared with other regimens (79% vs 61%, P=0.001) as excessive secondary graft failure was seen with other regimens (10% vs 26%, P=0.005) respectively. In multivariate analysis, aGvHD II-IV (hazard ratio (HR) 2.50, confidence interval (CI) 1.1-5.6, P=0.02) and aGvHD III-IV (HR 8.3 CI 3.4-20.2, P<0.001) proved to be independent negative predictors of survival. In conclusion, BM as a source of cells and ATG-based regimens should be standard because of higher GvHD incidence with PBSCs, although the latter combining with ATG in the conditioning regimen could be an option in selected high-risk patients.

Prevalence of CYP2C9 and VKORC1 alleles in the Argentine population and implications for prescribing dosages of anticoagulants.

Dicumarinic oral anticoagulants have a narrow therapeutic range and a great individual variability in response, which makes calculation of the correct dose difficult and critical. Genetic factors involved in this variability include polymorphisms of genes that encode the metabolic enzyme CYP2C9 and the target enzyme vitamin K epoxide reductase complex 1 (VKORC1); these polymorphisms can be associated with reduced enzymatic expression. We examined the frequency of the most relevant variants encoding CYP2C9 (alleles *1, *2 and *3) and VKORC1 (SNP -1639A>G) in the Argentinian population. Molecular typing was performed by PCR-RFLP on a randomly selected sample of 101 healthy volunteers from the Hospital Italiano de Buenos Aires gene bank. Fifty-seven subjects were identified as homozygous for CYP2C9*1 and 14 for *2, while 24 and 5 were heterozygous for *2 and *3 alleles; one individual was a composite heterozygote (*2/*3). When we examined VKORC1, 21 subjects were AA homozygous, 60 were AG heterozygotes and 20 were GG homozygotes. This is the first analysis of genotypic frequencies for CYP2C9 and VKORC1 performed in an Argentinian population. These allele prevalences are similar to what is known for Caucasian population, reflecting the European ancestor of our patient population, coming mostly from Buenos Aires city and surroundings. Knowledge of this prevalence information is instrumental for cost-effective pharmacogenomic testing in patients undergoing oral anticoagulation treatment.

New recurrent chromosome alterations in patients with multiple myeloma and plasma cell leukemia.

Chromosome abnormalities detected in metaphases from multiple myeloma (MM) cells have a clear impact on prognosis and response to therapy. Thirteen out of 50 (26%) patients with plasma cell disorders and abnormal karyotypes (11 with MM and 2 with plasma cell leukemia (PCL)) were selected for inclusion in the present report based on the presence of karyotypes with new and/or infrequent structural aberrations. Thirty-three new rearrangements, including a novel recurrent aberration: psu dic(5;1)(q35;q10), were detected. Chromosome 1 was the most frequently involved. Gains of genetic material (57%) were noted more frequently than losses (43%). Three rearrangements that were observed only once in the literature appear to be recurrent from our data: del(16)(q13), del(5)(p13) and i(3)(q10), the latter being a single structural aberration in the karyotype. Clinical parameters from our series were compared with 2 control groups: 20 MM cases with recurrent aberrations in MM/PCL with a similar distribution of abnormalities associated with poor prognosis (group 1), and 40 with normal karyotypes and fluorescence in situ hybridization analysis (group 2). Significantly increased serum calcium levels (p = 0.022) in patients with new and/or infrequent chromosome changes with respect to both control groups, and a higher percentage of bone marrow plasma cell infiltration (p = 0.005), ß(2) microglobulin, and lactate dehydrogenase levels (p < 0.0001) compared to group 2 were observed. Our results suggest that some of these novel rearrangements may be capable to deregulate genetic mechanisms related to the development and/or progression of the disease. The finding of new recurrent aberrations supports this hypothesis.