Juan Manuel Alonso-Domínguez

A common novel splice variant of SLC22A1 (OCT1) is associated with impaired responses to imatinib in patients with chronic myeloid leukaemia

Approximately one‐third of patients with chronic myeloid leukaemia will fail to achieve or maintain responses to imatinib. Changes in solute carrier family 22 (organic cation transporter), member 1 (SLC22A1, also termed OCT1), the main transporter for imatinib, have been proposed as a possible predictive factor. We analysed SLC22A1 mRNA levels and single nucleotide polymorphisms (SNPs) located in exon 7 in 153 diagnostic whole blood samples from two patient cohorts. The level of SLC22A1 expression did not significantly correlate with imatinib failure or achievement of molecular remission. The SNP 408V>M (g.1222G>A) was present in 65% of patients and was associated in all cases with an eight base‐pair insertion (8+ allele) at the 3′ end of exon 7. The latter generates an alternative splice site, leading to a premature stop codon. M420del was found in 33% of patients and never in cis with 8+ (the 3− allele). Significantly longer times to 1% and 0·1% molecular responses (by quantitative reverse transcription polymerase chain reaction) were seen in patients with 8+8+ or 8+N compared to those with the remaining four genotypes (N = no insertion or deletion). Patients lacking 8+ and 3− (NN, 18%) showed the best outcomes overall. Thus, while SLC22A1 expression does not appear to affect response, alterations in its splicing or amino acid sequence may do so.

PTCH1 expression at diagnosis predicts imatinib failure in chronic myeloid leukaemia patients in chronic phase

The tyrosine kinase inhibitor (TKI) imatinib has revolutionized the management of chronic myeloid leukaemia (CML). However, around 25% of patients fail to sustain an adequate response. We sought to identify gene‐expression biomarkers that could be used to predict imatinib response. The expression of 29 genes, previously implicated in CML pathogenesis, were measured by TaqMan Low Density Array in 73 CML patient samples. Patients were divided into low and high expression for each gene and imatinib failure (IF), probability of achieving CCyR, progression free survival and CML related OS were compared by Kaplan–Meier and log‐rank. Results were validated in a second cohort of 56 patients, with a further technical validation using custom gene‐expression assays in a conventional RT‐qPCR in a sub‐cohort of 37 patients. Patients with low PTCH1 expression showed a worse clinical response for all variables in all cohorts. PTCH1 was the most significant predictor in the multivariate analysis compared with Sokal, age and EUTOS. PTCH1 expression assay showed the adequate sensitivity, specificity and predictive values to predict for IF. Given the different treatments available for CML, measuring PTCH1 expression at diagnosis may help establish who will benefit best from imatinib and who is better selected for second generation TKI. Am. J. Hematol. 90:20–26, 2015.

Metastatic malignant melanoma detected on bone marrow aspiration

A 75-year-old man presented with asthenia and epistaxis of 3 weeks duration. He had been diagnosed with malignant melanoma 4 months previously, and had received intensive chemotherapy. Physical examination showed pallor, petechiae of both legs and splenomegaly. A blood count showed a haemoglobin concentration of 98 g/l, white cell count of 1 7 9 10/l and platelet count of 18 9 10/l. A blood film showed a leucoerythroblastic reaction; metastasis was suspected and a bone marrow aspiration and trephine biopsy were therefore performed. A May-Gr€ unwaldGiemsa stain revealed numerous clusters of non-haemopoietic cells containing black pigment (top left and top right), some with giant granules (bottom). Immunohistochemical staining of the biopsy specimen showed positivity for S-100 protein, thus confirming metastatic melanoma. Liver and spleen metastases were also identified on a computed tomography scan. The patient was treated palliatively and died 2 months later. Although metastasis of malignant melanoma to the bone marrow is infrequent, this possibility should be considered in the presence of pancytopenia or leucoerythroblastosis.

A BCR-ABL1 cutoff of 1.5% at 3 months, determined by the GeneXpert system, predicts an optimal response in patients with chronic myeloid leukemia

In chronic myeloid leukemia (CML) patients, 3-month BCR-ABL1 levels have consistently been correlated with further outcomes. Monitoring molecular responses in CML using the GeneXpert (Cepheid) platform has shown an optimal correlation with standardized RQ-PCR (IS) when measuring BCR-ABL1 levels lower than 10%, as it is not accurate for values over 10%. The aim of the present study was to determine the predictive molecular value at three months on different outcome variables using the Xpert BCR-ABL1 MonitorTM assay (Xpert BCR-ABL1). We monitored 125 newly diagnosed consecutive CML patients in the chronic phase (CML-CP) using an automated method: Xpert BCR-ABL1. Only 5% of patients did not achieve an optimal response at 3 months, and the 10% BCR-ABL1 cutoff defined by RQ-PCR (IS) methods was unable to identify significant differences in the probabilities of achieving a complete cytogenetic response (CCyR) (50% vs. 87%, p = 0.1) or a major molecular response (MMR) (60% vs. 80%, p = 0.29) by 12 months. In contrast, a cutoff of 1.5% more accurately identified differences in the probabilities of achieving CCyR (98% vs. 54%, p<0.001) and MMR (88% vs. 56%, p<0.001) by 12 months, as well as probabilities of treatment changes (p = 0.005). Therefore, when using the Xpert BCR-ABL1 assay, a cutoff of 1.5% at 3 months could with high probability identify patients able to achieve an optimal response at 12 months.

PTCH1 is a reliable marker for predicting imatinib response in chronic myeloid leukemia patients in chronic phase

Patched homolog 1 gene (PTCH1) expression and the ratio of PTCH1 to Smoothened (SMO) expression have been proposed as prognostic markers of the response of chronic myeloid leukemia (CML) patients to imatinib. We compared these measurements in a realistic cohort of 101 patients with CML in chronic phase (CP) using a simplified qPCR method, and confirmed the prognostic power of each in a competing risk analysis. Gene expression levels were measured in peripheral blood samples at diagnosis. The PTCH1/SMO ratio did not improve PTCH1 prognostic power (area under the receiver operating characteristic curve 0.71 vs. 0.72). In order to reduce the number of genes to be analyzed, PTCH1 was the selected measurement. High and low PTCH1 expression groups had significantly different cumulative incidences of imatinib failure (IF), which was defined as discontinuation of imatinib due to lack of efficacy (5% vs. 25% at 4 years, P = 0.013), probabilities of achieving a major molecular response (81% vs. 53% at first year, P = 0.02), and proportions of early molecular failure (14% vs. 43%, P = 0.015). Every progression to an advanced phase (n = 3) and CML-related death (n = 2) occurred in the low PTCH1 group (P<0.001 for both comparisons). PTCH1 was an independent prognostic factor for the prediction of IF. We also validated previously published thresholds for PTCH1 expression. Therefore, we confirmed that PTCH1 expression can predict the imatinib response in CML patients in CP by applying a more rigorous statistical analysis. Thus, PTCH1 expression is a promising molecular marker for predicting the imatinib response in CML patients in CP.

Gaucher disease and myelodysplastic syndrome with isolated del(5q)

An 80-year-old woman presented with asthenia of several weeks duration. She had been diagnosed with Gaucher disease 34 years earlier (N370S/N370S genotype, acid beta-glucosidase activity 18%, serum chitotriosidase levels: 1557 nmol/ml/h). She had been asymptomatic since then, with only mild splenomegaly, and no treatment had been required. A full blood count showed macrocytic anaemia (haemoglobin concentration (Hb) 109 g/l, MCV 122 fl) and a platelet count of 122 9 10/l. Serum vitamin B12 was reduced (112 pg/ml) and vitamin B12 therapy was therefore initiated. In spite of the normalization of platelet count and vitamin B12 levels, her Hb decreased and several red blood cell transfusions were needed. A bone marrow aspiration and trephine biopsy were therefore performed. A May-Gr€ unwald-Giemsa stain revealed numerous Gaucher cells and megakaryocytes with hypolobated nuclei (images). No other dysplastic features were found. Karyotype showed deletion of 5q in one out of 21 metaphases, and fluorescent in situ hybridization (FISH) for 5q deletion was positive in 51% and 66% of analysed nuclei in bone marrow and peripheral blood respectively. FISH for monosomy 7, trisomy 8, 20q deletion and 17p deletion yielded negative results, confirming a myelodysplastic syndrome with isolated del(5q) Treatment with lenalidomide (5 mg/day, days 1–21 every 28 days) was initiated. The patient is asymptomatic after three months of treatment, with Hb of 125 g/l, MCV 98 fl, leucocyte count 2 56 9 10/l and platelet count 88 9 10/l. It is well known that the incidence of cancer is increased in patients with Gaucher disease, especially multiple myeloma. Association with myelodysplastic syndromes is rare.