Characterization of a novel human anaplastic large cell lymphoma cell line tumorigenic in SCID mice

Establishment and characterization of TK-ALCL1: a novel NPM-ALK-positive anaplastic large-cell lymphoma cell line

TK-ALCL1, a novel anaplastic lymphoma kinase (ALK)-positive anaplastic large-cell lymphoma (ALK+ ALCL) cell line, was established from the primary tumor site of a 59-year-old Japanese male patient. The immune profile of TK-ALCL1 corresponds to that seen typically in primary ALCL cells, i.e., positive for ALK, CD30, EMA, and CD4, but negative for CD2, CD3, CD5, CD8a, and EBV-related antigens. The rearrangement of the T cell receptor-gamma locus shows that TK-ALCL1 is clonally derived from T-lineage lymphoid cells. FISH and RT-PCR analysis revealed that TK-ALCL1 has the nucleophosmin (NPM)-ALK fusion transcript, which is typical for ALK+ ALCL cell lines. When TK-ALCL1 was subcutaneously inoculated into 6-week-old BALB/c Rag2-/-/Jak3-/- (BRJ) mice, it formed tumor masses within 4-6 weeks. Morphological, immunohistochemical, and molecular genetic investigations confirmed that the xenograft and the original ALCL tumor were identical. The ALK inhibitors Alectinib and Lorlatinib suppressed proliferation in a dose-dependent manner. Thus, TK-ALCL1 provides a useful in vitro and in vivo model for investigation of the biology of ALK+ ALCL and of novel therapeutic approaches targeting ALK.

MYC expression is associated with older age, common morphology, increased MYC copy number, and poorer prognosis in patients with ALK+ anaplastic large cell lymphoma

The role of MYC dysregulation has been studied extensively in B-cell lymphomas, but little is known about its significance in T cell lymphomas. This study, for the first time in the literature, assessed the clinicopathologic and prognostic significance of MYC expression in ALK+ anaplastic large cell lymphoma (ALCL) cases. Using ≥50% as the cutoff value for positive MYC expression by immunohistochemistry, 17 of 46 (37%) cases were MYC+. Patients with MYC+ tumors were older (median age, 39 versus 29 years, p = 0.04) and more often showed a common morphologic pattern (100% versus 69%, p = 0.02), when compared with those with MYC-negative tumors. By fluorescence in situ hybridization analysis, 9 of 31 (29%) cases showed increased MYC copy number, and 1 of 31 (3%) case had an MYC rearrangement, and the remaining 21 (68%) cases showed no MYC aberrations. Among the cases with increased MYC copy number, 5 of 8 (62%) cases showed MYC copy gain and/or amplification and 3 of 8 (38%) had polysomy 8. MYC expression was associated with increased MYC copy number (p = 0.01). MYC expression, but not increased MYC copy number, correlated with shorter overall survival (OS) (p = 0.03). In conclusion, MYC expression identified a distinct group of ALK + ALCL patients with more aggressive behavior and shorter OS. Our data suggest that MYC expression is an adverse prognostic factor and may be useful in stratifying or predicting the prognosis of patients with ALK+ ALCL.

Targetable vulnerabilities in T- and NK-cell lymphomas identified through preclinical models

T- and NK-cell lymphomas (TCL) are a heterogenous group of lymphoid malignancies with poor prognosis. In contrast to B-cell and myeloid malignancies, there are few preclinical models of TCLs, which has hampered the development of effective therapeutics. Here we establish and characterize preclinical models of TCL. We identify multiple vulnerabilities that are targetable with currently available agents (e.g., inhibitors of JAK2 or IKZF1) and demonstrate proof-of-principle for biomarker-driven therapies using patient-derived xenografts (PDXs). We show that MDM2 and MDMX are targetable vulnerabilities within TP53-wild-type TCLs. ALRN-6924, a stapled peptide that blocks interactions between p53 and both MDM2 and MDMX has potent in vitro activity and superior in vivo activity across 8 different PDX models compared to the standard-of-care agent romidepsin. ALRN-6924 induced a complete remission in a patient with TP53-wild-type angioimmunoblastic T-cell lymphoma, demonstrating the potential for rapid translation of discoveries from subtype-specific preclinical models.

T- and NK-cell lymphomas (TCL) are a group of lymphoid malignancies characterized by poor prognosis, but the absence of appropriate pre-clinical models has hampered the development of effective therapies. Here the authors establish several pre-clinical models and identify vulnerabilities that could be further exploited to treat patients afflicted by these diseases.

The role of interleukin-9 in lymphoma

Although much progress has been made in the treatment of lymphomas, the unclear molecular etiology limits its further development. Interleukin-9 (IL-9) was initially described as a growth factor secreted by activated helper T cells type 2 (Th2). Various observations have demonstrated its diverse actions in immune and inflammatory responses. In recent years, a resurgence of interest in IL-9 has been spurred by the expanded identification of its cellular sources and biological targets. Also, the determination of its growth-proliferative and anti-apoptotic activities on multiple transformed cells implies a potential role of this cytokine in tumorigenesis. In this article we review the biologic properties and signal transduction pathways of IL-9, and furthermore discuss its possible role in lymphomagenesis as well as its impact on non-malignant infiltrating cells which are characteristic of the tumor microenvironment.

Microsatellite alterations and cell-free DNA analysis: could they increase the cytology sensitivity in the diagnosis of malignant pleural effusion?

BACKGROUND

The exact diagnosis of malignant pleural effusions (PE) is difficult and often requires combined procedures, because the cytological examination of pleural fluid does not detect tumoral cells in 40% of malignant effusion cases. The aim of this study was to analyze microsatellite alterations (MA) in malignant PE and to determine their diagnostic value as an additional test to cytological examination. The increase in cell-free DNA levels was also evaluated as a signal of probable malignancy.

METHODS

A total of 84 patients with PE were enrolled and underwent PE and whole blood and exhaled breath condensate analyses. Free DNA was measured by spectrophotometer analyses. DNA was extracted from all samples and analyzed for MA, using the microsatellite markers at chromosomes 3p, 12p, 5q, and 17p.

RESULTS

The microsatellite analysis of PE exhibited a higher percentage of alterations in malignant PE than in benign PE. In addition to this, cell-free DNA in PE was seen to be significantly more elevated in malignant than in benign PE. The sensitivity of the sole cytology increased considerably when patients showed at least one MA or DNA>4 ng/μL in the PE.

CONCLUSION

In conclusion, it was seen that the combination of the cytological examination with microsatellite analyses and cell-free DNA in pleural fluid could increase the sensitivity of the diagnosis in patients with PE who have a suspected malignancy, obviating the need for other invasive diagnostic procedures.

Programmed death ligand 1 is expressed by non-hodgkin lymphomas and inhibits the activity of tumor-associated T cells

PURPOSE

Programmed death ligand 1 (PD-L1) is expressed on antigen-presenting cells and inhibits activation of T cells through its receptor PD-1. PD-L1 is aberrantly expressed on some epithelial malignancies and Hodgkin lymphomas and may prevent effective host antitumor immunity. The role of PD-L1 in non-Hodgkin lymphomas (NHL) is not well characterized.

EXPERIMENTAL DESIGN

PD-L1 expression was analyzed in cell lines and lymphoma specimens by using flow cytometry and immunohistochemistry. Functional activity of PD-L1 was studied by incubating irradiated lymphoma cells with allogeneic T cells with or without anti-PD-L1 blocking antibody; T-cell proliferation and IFN-γ secretion served as measures of T-cell activation. Similar experiments were conducted using cultures of primary lymphoma specimens containing host T cells.

RESULTS

PD-L1 was expressed uniformly by anaplastic large cell lymphoma (ALCL) cell lines, but rarely in B-cell NHL, confined to a subset of diffuse large B-cell lymphomas (DLBCL) with activated B-cell features (3 of 28 cell lines and 24% of primary DLBCL). Anti-PD-L1 blocking antibody boosted proliferation and IFN-γ secretion by allogeneic T cells responding to ALCL and DLBCL cells. In autologous cultures of primary ALCL and DLBCL, PD-L1 blockade enhanced secretion of inflammatory cytokines IFN-γ, granulocyte macrophage colony-stimulating factor, interleukin (IL)-1, IL-6, IL-8, IL-13, TNF-α, and macrophage inflammatory protein-1α. In establishing cell lines from an aggressive PD-L1(+) mature B-cell lymphoma, we also noted that PD-L1 expression could be lost under certain in vitro culture conditions.

CONCLUSIONS

PD-L1 may thwart effective antitumor immune responses and represents an attractive target for lymphoma immunotherapy.

Amplification at 7q22 targets cyclin-dependent kinase 6 in T-cell lymphoma

Recurrent chromosomal aberrations in hematopoietic tumors target genes involved in pathogenesis. Their identification and functional characterization are therefore important for the establishment of rational therapies. Here, we investigated genomic amplification at 7q22 in the T-cell lymphoma cell line SU-DHL-1 belonging to the subtype of anaplastic large-cell lymphoma (ALCL). Cytogenetic analysis mapped this amplicon to 86-95 Mb. Copy-number determination quantified the amplification level at 5- to 6-fold. Expression analysis of genes located within this region identified cyclin-dependent kinase 6 (CDK6) as a potential amplification target. In comparison with control cell lines, SU-DHL-1 expressed considerably higher levels of CDK6. Functionally, SU-DHL-1 cells exhibited reduced sensitivity to rapamycin treatment, as indicated by cell growth and cell cycle analysis. Rapamycin reportedly inhibits degradation of the CDK inhibitor p27 with concomitant downregulation of cyclin D3, implying a proliferative advantage for CDK6 overexpression. Amplification of the CDK6 locus was analyzed in primary T-cell lymphoma samples and, while detected infrequently in those classified as ALCL (1%), was detected in 23% of peripheral T-cell lymphomas not otherwise specified. Taken together, analysis of the 7q22 amplicon identified CDK6 as an important cell cycle regulator in T-cell lymphomas, representing a novel potential target for rational therapy.

Pediatric ALK+ anaplastic large cell lymphoma with t(3;8)(q26.2;q24) translocation and c-myc rearrangement terminating in a leukemic phase

Pediatric ALK-positive anaplastic large cell lymphoma (ALK+ ALCL) is usually associated with a favorable prognosis. ALK+ ALCL associated with a leukemic phase is uncommon, but has been associated with an aggressive clinical course and unfavorable prognosis. Overexpression of c-myc has been shown to be a consistent finding in ALK+, but not ALK-negative ALCL (ALK- ALCL), and the c-myc gene is considered a downstream target of deregulated ALK signaling. We describe a pediatric ALK+ ALCL with a leukemic phase at relapse. Similar to other rare cases described in the literature, it followed an aggressive clinical course despite multiple regimens of chemotherapy and bone marrow transplantation. Lymphoma cells showed aberrant ALK expression and c-myc overexpression. In addition to the characteristic t(2;5)(p23;q35) translocation, a t(3;8)(q26.2;q24) translocation was also present, and c-myc gene rearrangement was confirmed by FISH analysis. The findings in this case demonstrate the association of peripheral blood leukemic involvement and aggressive clinical course, and suggest that other factors, such as c-myc rearrangement, may be responsible for the aggressive clinical behavior in ALK+ ALCL.

Isolation and comparative characterization of Ki-67 equivalent antibodies from the HuCAL phage display library

It has been shown that a repetitive motif with the sequence FKEL(F) within the Ki-67 antigen (pKi-67) serves as an epitope for the Ki-67 antibody and equivalent clones. However, no direct correlation between reactivity towards Ki-67 epitopes and reactivity in formalin-fixed paraffin-embedded (FFPE) tissue could be found. In this study our aim was the isolation and characterization of new monoclonal Ki-67 equivalent antibodies in an in vitro approach. To select pKi-67 reactive phage antibodies, we used a large naive Fab-phage library (Human Combinatorial Antibody Library; HuCAL). We implemented a panning strategy against two different overlapping peptides, both containing the 'FKELF' epitope. ELISA screening of randomly picked phage antibody clones after the third selection round yielded six highly reactive clones against the 'FKELF' epitope, of which five were found to be reactive in FFPE tissue, showing a Ki-67 equivalent staining pattern. Substitutional epitope analysis on peptide arrays of the new recombinant pKi-67 binders and of the established murine clones Ki-67, Mib-1 and Mib-5 were carried out to compare their fine specificities. The results suggest that the lysine residue in the epitope is critical for recognition of Ki-67 antigen in FFPE tissue.

Loss of expression of the WNT/beta-catenin-signaling pathway transcription factors lymphoid enhancer factor-1 (LEF-1) and T cell factor-1 (TCF-1) in a subset of peripheral T cell lymphomas

T cell factor-1 (TCF-1) and lymphoid enhancer factor-1 (LEF-1), members of the TCF/LEF family of transcription factors, play a significant role in T cell development and are expressed in thymocytes and peripheral CD3+ T cells. Previously, precursor T lymphoblastic leukemia/lymphoblastic lymphoma (T-ALL/LyL) was found to express TCF-1, and we find that 9 of 10 cases of T-ALL/LyL express LEF-1 as well as TCF-1, exhibiting uniform nuclear immunostaining for both transcription factors. In addition, a significant subset of cases of peripheral T cell lymphoma (PTCL), 39 of 81 cases (48%), are immunoreactive for LEF-1 and/or TCF-1, with 36 of 38 cases immunoreactive for both, indicating that these transcription factors are coordinately expressed in PTCL. The vast majority of LEF-1+ and/or TCF-1+ PTCL (34 of 39 or 87%) exhibit a composite Th1 T-cell-like immunophenotype, based on expression of Th1 T cell-associated, but not Th2 T cell-associated, chemokine receptors and activation markers. Of the Th1-like PTCL studied, 33 of 42 (79%) were immunoreactive for LEF-1 and 32 of 42 (76%) were immunoreactive for TCF-1, including most cases of angioimmunoblastic lymphoma and all cases of lymphoepithelioid lymphoma. Surprisingly, none of the 21 cases of Th2-like PTCL studied, all cases of anaplastic large cell lymphoma, were immunoreactive for LEF-1 or TCF-1 (P < 0.0001), suggesting that LEF-1 and TCF-1 transcription factor expression may be lost in Th2 T cells or Th2-like PTCL. LEF-1 and TCF-1 immunostaining can serve to identify specific subtypes of PTCL, and lends support to a bipartite model of PTCL development, based on expression of activation markers.

Multicolor-FICTION: expanding the possibilities of combined morphologic, immunophenotypic, and genetic single cell analyses

Phenotypic and genotypic analyses of cells are increasingly essential for understanding pathogenetic mechanisms as well as for diagnosing and classifying malignancies and other diseases. We report a novel multicolor approach based on the FICTION (fluorescence immunophenotyping and interphase cytogenetics as a tool for the investigation of neoplasms) technique, which enables the simultaneous detection of morphological, immunophenotypic, and genetic characteristics of single cells. As prerequisite, multicolor interphase fluorescence in situ hybridization assays for B-cell non-Hodgkin's lymphoma and anaplastic large-cell lymphoma have been developed. These assays allow the simultaneous detection of the most frequent primary chromosomal aberrations in these neoplasms, such as t(8;14), t(11;14), t(14;18), and t(3;14), and the various rearrangements of the ALK gene, respectively. To establish the multicolor FICTION technique, these assays were combined with the immunophenotypic detection of lineage- or tumor-specific antigens, namely CD20 and ALK, respectively. For evaluation of multicolor FICTION experiments, image acquisition was performed by automatic sequential capturing of multiple focal planes. Thus, three-dimensional information was obtained. The multicolor FICTION assays were applied to well-characterized lymphoma samples, proving the performance, validity, and diagnostic power of the technique. Future multicolor FICTION applications include the detection of preneoplastic lesions, early stage and minimal residual diseases, or micrometastases.