Molecular monitoring of 8p11 myeloproliferative syndrome in an infant.

The 8p11 myeloproliferative syndrome is a rare hematologic malignancy derived from a pluripotent hematopoietic stem cell associated with rearrangements involving the fibroblast growth factor receptor 1 (FGFR1) gene located on chromosome 8p11. The most common translocation, t(8;13) (p11;q13), results in a ZNF198-FGFR1 fusion gene and constitutively active FGFR1 tyrosine kinase activity. Typical pathologic findings include myeloid hyperplasia, lymphadenopathy, precursor T-lymphoblastic lymphoma, and eosinophilia. The disease is usually associated with an aggressive course and progression to acute myeloid leukemia is frequent. We report here the first case of 8p11 myeloproliferative syndrome in an infant and demonstrate the value of molecular testing in the diagnosis and minimal disease monitoring of this rare disease.

Sensitive detection of BRAF V600E mutation by Amplification Refractory Mutation System (ARMS)-PCR.

BACKGROUND: BRAF mutations occur in approximately 8% of all human cancers and approach 50% in melanoma and papillary carcinoma of thyroid. These mutations provide potentially valuable diagnostic, prognostic and treatment response prediction markers. A sensitive, specific, low-cost assay to detect these mutations is needed. RESULTS: To detect BRAF V600E mutation in formalin-fixed, paraffin-embedded (FFPE) tissue, we developed a method using Amplification Refractory Mutation System (ARMS)-PCR. This method was designed to amplify three products in a single reaction tube: a 200 bp common product serving as an amplification control, a 144 bp BRAF V600E specific product, and a 97 bp wild-type (wt) specific product. The sensitivity of this method was determined to be as low as 0.5% for the BRAF V600E allele in a wild-type background. This method was successfully validated in 72 thyroid tumors. It detected V600E mutation in 22 out of 33 (67%) of the conventional papillary thyroid carcinoma (PTC), 8 out of 12 (75%) of the tall-cell variant of PTC, whereas none of the 10 follicular variant of PTC showed BRAF V600E mutation. In addition, none of the 14 follicular adenomas and 3 follicular carcinomas had BRAF V600E mutation. As a comparison method, direct dideoxy sequencing found only 27 out of 30 (90%) mutations detected by ARMS-PCR method, suggesting that this ARMS-PCR method has higher sensitivity. CONCLUSIONS: Our ARMS-PCR method provides a new tool for rapid detection of BRAF V600E mutation. Our results indicate that ARMS-PCR is more sensitive than automated dideoxy sequencing in detecting low BRAF V600E allele burdens in FFPE tumor specimen. The strategy of this ARMS-PCR design may be adapted for early detection of point mutations of a variety of biomarker genes.

Predictors of primary imatinib resistance in chronic myelogenous leukemia are distinct from those in secondary imatinib resistance.

PURPOSE: A subset of patients with chronic myelogenous leukemia (CML) do not respond to the tyrosine kinase inhibitor (TKI) imatinib mesylate. Such primary imatinib resistance is distinguished from secondary resistance which reemerges after attainment of cytogenetic remission. PATIENTS AND METHODS: We studied gene expression patterns in total WBCs using a panel of 21 genes previously implicated in TKI handling, resistance, or progression comparing patients who had newly diagnosed TKI-naive CML that had optimal (n = 41), or suboptimal (n = 7) responses to imatinib, or primary resistance (n = 20). Expression patterns were compared to those in secondary TKI-resistant chronic phase CML without ABL1 kinase domain mutations (n = 29), and to lymphoid (n = 15) or myeloid blast phase disease (n = 12). RESULTS: Fifteen genes in the panel distinguished blast phase from chronic phase disease, and 12 genes distinguished newly diagnosed CML from TKI-resistant CML without ABL1 kinase domain mutations, but only a single gene, prostaglandin-endoperoxide synthase 1/cyclooxgenase 1 (PTGS1/COX1; P = .005), differentiated imatinib-responsive from primary imatinib-resistant CML. The association of primary imatinib resistance with higher transcript levels of the drug metabolism gene PTGS1 was confirmed in a separate data set of 68 newly diagnosed, imatinib-treated CML (P = .008). In contrast, up to 11 different genes were identified in a multivariate model that optimally discriminated secondary imatinib resistance lacking ABL1 kinase domain mutation from imatinib-responsive cases, likely related to the more complex pathogenesis of secondary resistance. CONCLUSION: Gene expression profiling of CML at diagnosis for PTGS1 may be useful in predicting imatinib response and in selecting alternate therapy.