Jinming Song

ASXL1 frameshift mutations drive inferior outcomes in CMML without negative impact in MDS

Next-generation sequencing (NGS) has revolutionized the diagnostic, prognostic and treatment paradigms in myeloid malignancies. Although somatic mutations can be identified in the majority of patients with myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CMML), the mutational spectrum and prognostic significance of individual mutations is dependent on disease subtype and remains incompletely understood. In CMML, mutations in the addition of sex combs-like 1 (ASXL1) gene are the only mutations consistently associated with inferior survival in multivariable analysis and as such refine discrimination of clinical prognostic models. Nonetheless, these studies also suggest that the type of mutation may have prognostic significance as ASXL1 missense mutations are not similarly predictive of clinical outcomes. Additional studies have confirmed the prognostic significance of ASXL1 mutations in CMML while also identifying mutations of CBL, RUNX1, NRAS, and SETBP1 to have prognostic relevance. In MDS, mutations involving TP53, EZH2, ETV6, RUNX1, and ASXL1 genes are associated with inferior survival, albeit ASXL1 mutations are of only borderline significance. Importantly, the prognostic relevance of type of ASXL1 mutation has not been analyzed in MDS patients. These data suggest that there are distinct disease-specific implications in MDS versus CMML that apply to a similar mutational spectrum. Given the predicted differences in prognostic significance of ASXL1 between MDS and CMML, we sought to compare the impact of ASXL1 mutations in a combined cohort comprised of both diseases. We identified that although ASXL1 mutation was predictive for outcome in CMML (HR 2.97, 95% CI 1.21–7.06; P= 0.02), it had no impact on outcome in MDS patients (HR 1.04, P= 0.87). In addition, whereas the negative significance of ASXL1 mutation status was dependent on frameshift (FS) mutations (HR 3.85, 95% CI 1.84–15.61, P= 0.0026) in CMML, the type of mutation had no impact on MDS prognosis even when accounting for missense mutations. Patients were identified retrospectively from the Moffitt Cancer Center (MCC) database that had NGS performed and a diagnosis of CMML or MDS according to WHO criteria (including patients with refractory anemia with excess blasts in transformation according to FAB). Pathology review was performed at MCC. This study was approved by the MCC Scientific Review Committee and institutional review board. From May 2013 to July 2015, a total of 60 CMML patients were identified who underwent NGS who were compared to a cohort of 195 MDS patients (Table 1). From May 2013 to October 2014, targeted amplicon based NGS of 21 myeloid genes was performed on DNA extracted from mononuclear cells of BM aspirate or peripheral blood as previously described, which was followed by NGS using a 32 gene panel. The lower limit of detection for variant calling was set at a 5% variant allele frequency (VAF) and the minimum depth of coverage was 500×. Clinical characteristics were cataloged from the date of mutation analysis. Kaplan–Meier estimates were used to estimate OS and analyzed from the date of mutation identification. Cox regression models were cr7eated to adjust for clinical characteristics. Categorical and continuous variables were compared by Fisher’s exact test and Mann–Whitney’s test, respectively.

Comparison of the Mutational Profiles of Primary Myelofibrosis, Polycythemia Vera, and Essential Thrombocytosis

Abstract Objectives: To compare the mutational profiles of patients with primary myelofibrosis (PMF), polycythemia vera (PV), and essential thrombocytosis (ET). Methods: Next-generation sequencing results of 75 cases of PMF, 33 cases of PV, and 27 cases of ET were compared. Results: Mutation rates of ASXL1 and SRSF2 were significantly higher in PMF than in PV or ET. ASXL1 mutations appeared to be more frequently associated with risk of transformation to acute myeloid leukemia than JAK2 or TET2 mutations. The most common mutation-cytogenetic combinations in myeloproliferative neoplasm (MPN) were mutations of JAK2 or ASXL1 with del(20q) and were more common in patients with PMF and PV than in patients with ET. Differences were also found between patients with PMF and PV. Conclusions: PMF, PV, and ET show different mutational profiles, which may be helpful in resolving the differential diagnosis between MPNs. Due to the relatively small number of cases and variable testing over time, larger controlled studies are necessary to confirm the findings.

Primary lymphomatous presentation of hairy cell leukemia as osteolytic vertebral lesions: a case report

Hairy cell leukemia (HCL) is a rare and indolent mature B cell neoplasm. Most patients with HCL have excellent response to purine analogs and BRAF inhibitors. Therefore, it is clinically important to identify and differentiate HCL from other B cell neoplasms. HCL is predominantly found in the peripheral blood, bone marrow, or spleen. HCL presenting initially or solely in unusual sites is extremely rare (approximately ten or fewer). We hereby report a unique case of HCL presenting as vertebral osteolytic and epidural mass lesions without bone marrow, spleen, or peripheral blood involvement. The patient was a 53-year-old male with acute and chronic radicular pain down the posterior aspect of bilateral thighs. Imaging study with MRI demonstrated a L4 posterior vertebral osteolytic mass lesion, extending into the spinal canal, and a second right sacral S1 lesion extending into the sacral iliac joint. These two noncontiguous lesions were thought to be consistent with metastatic cancer or sarcoma, and the specimen was submitted to non-hematopoietic pathologist for diagnosis without flow cytometry. Initial immunohistochemical stains were ordered for solid tumor markers, which were all negative. As part of the workup, immunostain for BRAF V600E (VE1) was ordered for melanoma, and CD138 and cyclin D1 for myeloma, which returned positive and suggested the possibility of hairy cell leukemia. Additional workup for hairy cell leukemia confirmed the diagnosis. HCL typically presents with peripheral blood, bone marrow, or spleen involvement, while mass lesions in other sites are rare. High index of suspicion is essential for the correct diagnosis of HCL in mass lesions at unusual sites. In the absence of initial hematopathological workup and flow cytometry, HCL presenting as solid mass in unusual locations is misdiagnosed most likely as marginal zone B cell lymphoma (mucosa-associated lymphoid tissue (MALT) lymphoma). The expression of cyclin D1, TRAP, annexin A1, and BRAF V600E mutation would confirm the diagnosis of HCL. The main differentials include MALT lymphoma, mantle cell lymphoma (MCL), and hairy cell leukemia variant (HCLv). This case report will be interesting for the clinicians and pathologists alike and broaden the spectrum of clinical presentation of lymphomatous HCL.

Association of EZH2 protein expression by immunohistochemistry in myelodysplasia related neoplasms with mutation status, cytogenetics and clinical outcomes

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