Faculty Bibliography

Smoldering myeloma (SMM) is associated with a high-risk of progression to myeloma (MM). We report the results of a study of 82 patients with both targeted sequencing that included a capture of the immunoglobulin and MYC regions. By comparing these results to newly diagnosed myeloma (MM) we show fewer NRAS and FAM46C mutations together with fewer adverse translocations, del(1p), del(14q), del(16q), and del(17p) in SMM consistent with their role as drivers of the transition to MM. KRAS mutations are associated with a shorter time to progression (HR 3.5 (1.5-8.1), p = 0.001). In an analysis of change in clonal structure over time we studied 53 samples from nine patients at multiple time points. Branching evolutionary patterns, novel mutations, biallelic hits in crucial tumour suppressor genes, and segmental copy number changes are key mechanisms underlying the transition to MM, which can precede progression and be used to guide early intervention strategies.

Multiparametric flow cytometry (FC) of CSF allows one to easily estimate the percentage of lymphocyte subpopulations in CSF. We hypothesized that an increased ratio of B-lineage cells in CSF of MS patients, as assessed with FC, could be useful for diagnostics. We analyzed CSF of 137 patients (70 MS, 24 infectious/autoimmune neurologic disorders (INDs), and 43 non-infectious/autoimmune neurologic disorders (NINDs)), and showed that CSF plasmablasts of >0.1% had a sensitivity of 40% for MS and specificity of 92% when comparing MS and IND, while plasmablasts of >0.25% had sensitivity of 36%, and 100% specificity.

Objective: Hairy cell leukemia (HCL) is distinct indolent neoplasm of small mature B cells accounting for 2% of the lymphoid leukemias. The classic immunophenotypic profile of HCL includes bright expression of B cell surface antigen and immunoglobulins and lack of both CD5 and CD10. The tumor cells are predominantly present in the spleen, peripheral blood and bone marrow. Aberrant expression of CD5 and lymph node involvement are very rare. A case of CD5(+) HCL with a documentedBRAF V600Emutation has not been previously reported. This case is also unique due to lymph node involvement by HCL. To our knowledge, this is the only case report of a documentedBRAF V600Emutated CD5(+) HCL along with lymph node involvement in the literature.
Method(s): We are presenting a 45 years old man with multiple prior medical conditions including diabetes, COPD and interstitial pneomonitis with new onset of B-symptoms and neutropenia/monocytopenia. Peripheral blood flow cytometry revealed 21% CD5(+) CD10(-) monoclonal B cell population. Further workup revealed the neoplastic cells are positive for CD11c, CD103 and CD25. Bone marrow study revealed an extensive involvement of the marrow.By immunohistochemistry, the cells are also positive for CD5, CD20, BRAF and cyclin D1. Cytogenetic studies show that the cells are negative t(11;14) and molecular studies revealedBRAF V600Emutation. Reexamination of the prior wedge lung resection revealed intrathoracic lymph node involvement.
Result(s) and Conclusion(s): The most common differential diagnoses of a CD5(+) B cell lymphoma involving the bone marrow is chronic lymphocytic leukemia (CLL) and mantle cell lymphoma. The key into the diagnosis of this case was marked monocytopenia that lead to addition of HCL antibody tubes despite the CD5 positivity and detection of CD25, CD103 and CD11c antigens in the leukemic cells. Bone marrow biopsy show extensive involvement by a CD5(+) cyclin D1(+) B cell lymphoma. The most important differential diagnosis in this case was mantle cell lymphoma. The diagnosis of HCL was confirmed by detection ofBRAF V600Emutation and absence of t (11;14). Retrospective examination of the intrathoracic lymph nodes show one lymph node involvement by hairy cell leukemia cells. The patient was treated with Vemurafenib and his follow up flow cytometry revealed only 0.60% leukemic involvement. Incorporation of clinical data at the time of flow cytometric examination is essential to aid the hematopathologist in having a broader differential diagnoses and addition of appropriate tests that lead to the more accurate diagnosis and treatment. [Formula presented] Disclosures: No relevant conflicts of interest to declare.
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Epigenetic plasticity is a pivotal factor that drives metastasis. Here, we show that the promoter of the gene that encodes the ubiquitin ligase subunit FBXL7 is hypermethylated in advanced prostate and pancreatic cancers, correlating with decreased FBXL7 mRNA and protein levels. Low FBXL7 mRNA levels are predictive of poor survival in patients with pancreatic and prostatic cancers. FBXL7 mediates the ubiquitylation and proteasomal degradation of active c-SRC after its phosphorylation at Ser 104. The DNA-demethylating agent decitabine recovers FBXL7 expression and limits epithelial-to-mesenchymal transition and cell invasion in a c-SRC-dependent manner. In vivo, FBXL7-depleted cancer cells form tumours with a high metastatic burden. Silencing of c-SRC or treatment with the c-SRC inhibitor dasatinib together with FBXL7 depletion prevents metastases. Furthermore, decitabine reduces metastases derived from prostate and pancreatic cancer cells in a FBXL7-dependent manner. Collectively, this research implicates FBXL7 as a metastasis-suppressor gene and suggests therapeutic strategies to counteract metastatic dissemination of pancreatic and prostatic cancer cells.

Background: The 2017 WHO update on hematological malignancies recognizes lymphomas of follicular helper T-cell (TFH) origin which include angioimmunoblastic T-cell lymphoma (AITL) as well as the provisional entities follicular peripheral T-cell lymphoma (F-PTCL) and nodal PTCL with TFH phenotype (PTCL-TFH). Demonstration of TFH derivation requires expression of at least 2 or 3 antigens among CD279/PD1, CD10, BCL6, CXCL13, ICOS, SAP, and CCR5, but these markers are frequently not co-expressed. We hypothesized that evaluation of normal TFH cells may identify novel markers that may aid in identifying TFH-derived neoplasms as well as resolve potential biological heterogeneity amongst them.
Design(s): In order to identify potential novel TFH markers, we evaluated RNA-sequencing data generated from human TFH cells, T-effector (Teff), and naive T-cells available from the GEO database (GSE58596). Among differentially expressed genes (DEGs), a subset was assessed for their ability to stain a tissue microarray representing a variety of T-cell neoplasms using commercially available antibodies (TIM1, HES6, HDAC9, TGFBR3). Each marker was scored by at least two pathologists for staining intensity and frequency of neoplastic Tcells in two separate cores to obtain an H-score; an H-score > 5 was defined as positive.
Result(s): We identified 132 genes (p value <0.05) highly expressed in TFH cells compared to both Teff and naive T-cells; these genes did not include CD279/PD1, CD10, BCL6, CXCL13, ICOS, SAP, or CCR5. While HES6 and TIM1 immunostains highlighted cells similar in number and distribution to established TFH markers such as PD1, ICOS, and CXCL13 in normal lymphoid tissue, HDAC9 and TGFBR3 were more broadly expressed. TGFBR3 was frequently expressed in AITL, MF, and ALK- ALCL, but was expressed in a smaller frequency of PTCL, NOS cases. While TIM1 and TGFBR3 highlighted the majority of AITL and PTCL, NOS cases, small subsets of AITL and PTCL, NOS cases expressed only TIM1 or TGFBR3. A summary of staining frequencies for each candidate TFH marker is shown in the table below. (Figure presented)
Conclusion(s): Overall, these findings suggest that TGFBR3 and TIM1 may be used as TFH markers and also suggest that presumed TFHderived neoplasms exhibit additional biological heterogeneity with respect to TFH marker expression. A more detailed comparison of TIM1 and TGFBR3 to commonly used TFH markers will be required to confirm the utility of these markers in the clinical diagnostic setting