Hematopoietic clonal dominance, stem cell mutations, and evolutionary pattern of JAK2V617F allele burden in polycythemia vera.

OBJECTIVES: Clonal dominance is characteristic of patients with post-polycythemia vera myelofibrosis (post-PV MF), whereas patients in chronic phase usually display polyclonal hematopoiesis. The aim of this work was to study the mutational burden of JAK2V617F at the progenitor level in patients with PV and correlate it with the evolutive phase of the disease and the presence of mutations in genes different to JAK2V617F. METHODS: JAK2V617F was measured in stem cells, progenitor cells, and granulocytes of 45 patients with PV (early chronic phase n = 26, late chronic phase n = 10, post-PV MF n = 9). In addition, screening of TET2, DNMT3A, ASXL1, SF3B1, SRSF2, U2AF1, and TP53 was performed with quantification of the mutation in CD34+ cells in positive cases. Moreover, we assessed whether JAK2V617F allele burden in granulocytes (at a single time point or monitoring) could be used as a surrogate of clonal dominance. RESULTS: Ten patients presented clonal dominance at progenitor level (PV at diagnosis n = 2, late chronic phase n = 1, post-PV MF n = 7). Additional mutations were identified in four patients at diagnosis, three in TET2, and one in DNMT3A gene, with clonal dominance present in three of them. At PV diagnosis, clonal dominance was demonstrated only in patients with additional mutations. JAK2V617F monitoring showed better diagnostic accuracy than single time point measurement as a marker of clonal dominance. CONCLUSIONS: Clonal dominance may be present at diagnosis, especially in those cases carrying other mutations. JAK2V617F monitoring during follow-up could help in the identification of patients with clonal dominance.

Detection of HPV by in situ hybridization in thin-layer (ThinPrep) cervicovaginal samples.

We have studied an automated in situ hybridization (ISH) method as a possible alternative approach for detecting high-risk human papillomavirus (HPV) in monolayer (ThinPrep) cervico-vaginal samples, comparing the results with those obtained by polymerase chain reaction (PCR) using consensus primers and studying the relationship between the ISH staining pattern and the viral integration in HPV 16-positive cases. Eighty atypical squamous cells of undetermined significance (ASCUS) and low-grade squamous intraepithelial lesion (LSIL) cases were used for our purposes. The patients were monitored through periodic cytologies. ISH with was performed with an automated Ventana System, analysis by PCR was performed with consensus primers and integration of HPV16 was performed by realtime PCR analyzing E2 and E6 genes. Additionally, 27 HSIL cases were also studied to observe the ISH staining patterns. HPV infection was detected by ISH in 21.7% of the ASCUS cases and 55.8% of the LSIL cases. Two distinct staining patterns were observed: multipunctated (MP) and diffuse (DI). In some cases, a mixed pattern (MP + DI) was observed and these cases were considered as MP. The MP pattern increased with the degree of lesion and seemed to have a prognostic value in ASCUS/LSIL cases. The lesion in MP pattern cases persisted throughout the entire study in 77% of cases, whereas in cases with a DI staining pattern, only 41% of them showed persistence of the lesion (p <0.001). No correlation was found between HPV integration and the ISH staining pattern. Given the lower sensitivity and negative predictive value of ISH and its incapacity to demonstrate the integration of high-risk HPV in ASCUS and LSIL cases using liquid-based cytology, we do not recommend this technique for the triage of ASCUS and LSIL cases.

MicroRNAs 142-3p, miR-155 and miR-203 Are Deregulated in Gastric MALT Lymphomas Compared to Chronic Gastritis.

BACKGROUND: Over the last years, our knowledge on pathogenesis of gastric MALT lymphoma has greatly improved, but its morphological diagnosis is still hampered by overlapping histological features with advanced chronic gastritis. MicroRNAs are deregulated in lymphomas, but their role and usefulness in gastric MALT lymphoma has not been extensively investigated. MATERIALS AND METHODS: We analyzed the expression of 384 miRNAs using TaqMan microRNA assay in a training series of 10 gastric MALT lymphomas, 3 chronic gastritis and 2 reactive lymph nodes. Then, significantly deregulated miRNAs were individually assessed by real-time PCR in a validation series of 16 gastric MALT lymphomas and 12 chronic gastritis. RESULTS: Gastric MALT lymphoma is characterized by a specific miRNA expression profile. Among the differentially expressed miRNAs, a significant overexpression of miR-142-3p and miR-155 and down-regulation of miR-203 was observed in gastric MALT lymphoma when compared to chronic gastritis. CONCLUSION: miR-142-3p, miR-155 and miR-203 expression levels might be helpful biomarkers for the differential diagnosis between gastric MALT lymphomas and chronic gastritis.

Characterization of CD34+ hematopoietic progenitor cells in JAK2V617F and CALR-mutated myeloproliferative neoplasms.

Mutations in JAK2 or CALR are observed in patients with myeloproliferative neoplasms (MPN). To get further insight in the dynamics of the mutant clone, we assessed the mutant allele burden in hematopoietic stem cells (HSCs), hematopoietic progenitor cells (HPCs) and granulocytes from 138 patients [51 polycythemia vera (PV), 58 essential thrombocythemia (ET) and 29 myelofibrosis (MF)]. CALR-mutated ET patients harbored a higher mutant load at progenitor level than JAK2V617F-positive ET (HSCs: 39.9% vs 7.5% p<0.001, HPCs: 32.7% vs 7.7% p<0.001). Moreover, HSCs of CALR-mutated ET patients showed a similar mutational load than patients with CALR-mutated MF (39.9% vs 48.2%, p=0.17). Regarding JAK2V617F MPN, PV and ET patients showed a low mutational burden at progenitor level whereas in the myelofibrotic phase the dominance of the mutated clone was a constant finding. In conclusion, the size of the mutated clone in chronic phase MPN is different according to genotype with CALR-mutated ET showing a pattern similar to that observed in MF.

Anti-tumor activity of the combination of bendamustine with vorinostat in diffuse large B-cell lymphoma cells.

Current standard-of-care therapy for diffuse large B-cell lymphoma (DLBCL) results in up to 40% of patients who either relapse or develop refractory disease. In this setting, further therapeutic improvements are needed. This study analyzed the in vitro effects of the combination of bendamustine with the histone deacetylase inhibitor vorinostat in DLBCL cells. This combination enhanced histone acetylation and double strand DNA breaks resulting in an additive to synergistic cytotoxic effect in both ABC- and GCB-type DLBCL cells, independently of their TP53 mutational status. These results support the rationale for considering bendamustine and vorinostat combination as a novel approach in DLBCL treatment.

Genetic predisposition to molecular response in patients with myeloproliferative neoplasms treated with hydroxycarbamide.

JAK2V617F allele burden was prospectively measured in polycythemia vera (PV, n=52) and essential thrombocythemia (ET, n=39) patients receiving hydroxycarbamide (HC) and analyzed according to JAK2 46/1 haplotype and genotype of SLC14A1, SLC14A2 and ARG2 urea transporters. Molecular response (MR) was obtained in 68.7% and 38.9% of PV patients with GG and AA or GA genotype in SLC14A2, respectively (p=0.07). No significant differences were observed neither in PV nor in ET according to JAK2 46/1 haplotype, SLC14A1 and ARG2. In conclusion, JAK2 46/1 haplotype does not influence MR in HC treated patients and urea transporters polymorphisms display a minimal effect.

Genomic arrays in chronic lymphocytic leukemia routine clinical practice: are we ready to substitute conventional cytogenetics and fluorescence in situ hybridization techniques?

Chronic lymphocytic leukemia (CLL) is characterized by a highly variable clinical course. Del(11q) and del(17p), routinely studied by conventional G-banding cytogenetics (CGC) and fluorescence in situ hybridization (FISH), have been related to progression and shorter overall survival. Recently, array-based karyotyping has gained acceptance as a high-resolution new tool for detecting genomic imbalances. The aim of the present study was to compare genomic arrays with CGC and FISH to ascertain whether the current techniques could be substituted in routine procedures. We analyzed 70 patients with CLL using the Cytogenetics Whole-Genome 2.7M Array and CytoScan HD Array (Affymetrix), CGC and FISH with the classical CLL panel. Whereas 31.4% and 68.6% of patients presented abnormalities when studied by CGC and FISH, respectively, these rates increased when arrays were also analyzed (78.6% and 80%). Although abnormality detection is higher when arrays are applied, one case with del(11q) and three with del(17p) were missed by genomic arrays due to their limited sensitivity. We consider that the complete substitution of CGC and FISH by genomic arrays in routine laboratories could negatively affect the management of some patients harboring 11q or 17p deletions. In conclusion, genomic arrays are valid to detect known and novel genomic imbalances in CLL, but should be maintained as a complementary tool to the current techniques.

PCR study of a series of ASCUS cases HPV-positive by HCII.

Most guidelines currently recommend the testing of human papillomavirus (HPV) in ASCUS cases. The most used method for this purpose is Hybrid Capture II (HCII), but PCR techniques with GP5+/6+ primers can be also applied. Furthermore, the HCII high-risk probe test for detection of HPV shows cross-reactivity with low-risk HPV. Although this cross-reactivity has been studied in screening populations, it has received little attention in ASCUS cases. To compare the performance of the HCII high-risk probe test and PCR for the detection of HPV in ASCUS cases. We randomly selected 83 ASCUS cases that were positive for high-risk HPV by HCII and applied the PCR test using MYO9-11 and GP5+/6+ primers to samples from these cases. Our results show cross-reactivity with low-risk HPV in 25.3% (21/83) of the HCII+ PCR+ cases. Regarding the follow-up our results emphasize the importance of HPV typing, especially for HPV 16 infection. We propose the use of PCR techniques using GP5+/6+ consensus primers for the screening of HPV in ASCUS.

Identification of a mutation in the extracellular domain of the Epidermal Growth Factor Receptor conferring cetuximab resistance in colorectal cancer.

Antibodies against epidermal growth factor receptor (EGFR)--cetuximab and panitumumab--are widely used to treat colorectal cancer. Unfortunately, patients eventually develop resistance to these agents. We describe an acquired EGFR ectodomain mutation (S492R) that prevents cetuximab binding and confers resistance to cetuximab. Cells with this mutation, however, retain binding to and are growth inhibited by panitumumab. Two of ten subjects studied here with disease progression after cetuximab treatment acquired this mutation. A subject with cetuximab resistance harboring the S492R mutation responded to treatment with panitumumab.