Anaplastic large cell lymphoma: one or more entities among T-cell lymphoma?

Tyrosine kinases in nodal peripheral T-cell lymphomas

Nodal peripheral T-cell lymphomas (PTCL) are uncommon and heterogeneous tumors characterized by a dismal prognosis. Targeted therapy has been proposed. However, reliable targets are mostly represented by a few surface antigens (e.g., CD52 and CD30), chemokine receptors (e.g., CCR4), and epigenetic gene expression regulation. In the last two decades, however, several studies have supported the idea that tyrosine kinase (TK) deregulation might be relevant for both the pathogenesis and treatment of PTCL. Indeed, they can be expressed or activated as a consequence of their involvement in genetic lesions, such as translocations, or by ligand overexpression. The most striking example is ALK in anaplastic large-cell lymphomas (ALCL). ALK activity is necessary to support cell proliferation and survival, and its inhibition leads to cell death. Notably, STAT3 was found to be the main downstream ALK effector. Other TKs are consistently expressed and active in PTCLs, such as PDGFRA, and members of the T-cell receptor signaling family, such as SYK. Notably, as in the case of ALK, STAT proteins have emerged as key downstream factors for most of the involved TK.

Identification and Characterization of Cancer Stem-Like Cells in ALK-Positive Anaplastic Large Cell Lymphoma Using the SORE6 Reporter

Transcription factors Sox2 and Oct4 are essential in maintaining the pluripotency of embryonic stem cells and conferring stemness in cancer stem-like (CSL) cells. SORE6, an in-vitro reporter system, was designed to quantify the transcription activity of Sox2/Oct4 and identify CSL cells in non-hematologic cancers. Using SORE6, we identified and enriched CSL cells in ALK-positive anaplastic large cell lymphoma (ALK + ALCL). Two ALK + ALCL cell lines, SupM2 and UCONN-L2, contained approximately 20% of SORE6+ cells, which were purified based on their expression of green fluorescent protein. We then performed functional studies using single-cell clones derived from SORE6− and SORE6+ cells. Compared to SORE6− cells, SORE6+ cells were significantly more chemoresistant and clonogenic in colony-formation assays. Sox2/Oct4 are directly involved in conferring these CSL properties, since the shRNA knockdown of Sox2 in SORE6+ significantly lowered their chemoresistance, while enforced expression of Sox2/Oct4 in SORE6− cells produced opposite effects. Using Western blots, we found that the expression and subcellular localization of Sox2/Oct4 were similar between SORE6− and SORE6+ cells. However, in SORE6+ but not SORE6− cells, Sox2 and Oct4 abundantly bound to a probe containing the SORE6 consensus sequence. c-Myc, previously shown to regulate cancer stemness in ALK + ALCL, regulated the SORE6 activity. In conclusion, SORE6 is useful in identifying/enriching CSL cells in ALK + ALCL.

CRISPR genome editing of murine hematopoietic stem cells to create Npm1-Alk causes ALK+ lymphoma after transplantation

CRISPR/Cas9 genomic editing of wild-type hematopoietic stem cells generates Npm1-Alk, leading to ALK+ large-cell lymphomas in recipients. CD30+ postthymic T-cell lymphomas are polyclonal but transplantable to secondary recipients with long latency.

CD30-positive primary cutaneous lymphoproliferative disorders: molecular alterations and targeted therapies

Primary cutaneous CD30-positive T-cell lymphoproliferative disorders are the second most common subgroup of cutaneous T-cell lymphomas. They include two clinically different entities with some overlapping features and borderline cases: lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma. Molecular studies of primary cutaneous anaplastic large cell lymphoma reveal an increasing level of heterogeneity that is associated with histological and immunophenotypic features of the cases and their response to specific therapies. Here, we review the most significant genetic, epigenetic and molecular alterations described to date in primary cutaneous CD30-positive T-cell lymphoproliferative disorders, and their potential as therapeutic targets.

New Therapies and Immunological Findings in Cutaneous T-Cell Lymphoma

Primary cutaneous lymphomas comprise a group of lymphatic malignancies that occur primarily in the skin. They represent the second most common form of extranodal non-Hodgkin’s lymphoma and are characterized by heterogeneous clinical, histological, immunological, and molecular features. The most common type is mycosis fungoides and its leukemic variant, Sézary syndrome. Both diseases are considered T-helper cell type 2 (Th2) diseases. Not only the tumor cells but also the tumor microenvironment can promote Th2 differentiation, which is beneficial for the tumor cells because a Th1 environment enhances antitumor immune responses. This Th2-dominant milieu also underlies the infectious susceptibility of the patients. Many components, such as tumor-associated macrophages, cancer-associated fibroblasts, and dendritic cells, as well as humoral factors, such as chemokines and cytokines, establish the tumor microenvironment and can modify tumor cell migration and proliferation. Multiagent chemotherapy often induces immunosuppression, resulting in an increased risk of serious infection and poor tolerance. Therefore, overtreatment should be avoided for these types of lymphomas. Interferons have been shown to increase the time to next treatment to a greater degree than has chemotherapy. The pathogenesis and prognosis of cutaneous T-cell lymphoma (CTCL) differ markedly among the subtypes. In some aggressive subtypes of CTCLs, such as primary cutaneous gamma/delta T-cell lymphoma and primary cutaneous CD8⁺ aggressive epidermotropic cytotoxic T-cell lymphoma, hematopoietic stem cell transplantation should be considered, whereas overtreatment should be avoided with other, favorable subtypes. Therefore, a solid understanding of the pathogenesis and immunological background of cutaneous lymphoma is required to better treat patients who are inflicted with this disease. This review summarizes the current knowledge in the field to attempt to achieve this objective.

An Exploration into the Origins and Pathogenesis of Anaplastic Large Cell Lymphoma, Anaplastic Lymphoma Kinase (ALK)-Positive

T-cell non-Hodgkin lymphoma is a heterogeneous disease ranging from malignancies arising from thymic T cells halted in development, through to mature, circulating peripheral T cells. The latter cases are diagnostically problematic with many entering the category of peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS). Anaplastic large cell lymphoma (ALCL) is one of the exceptions to this whereby aberrant expression of anaplastic lymphoma kinase (ALK) and the distinctive presence of cell surface CD30 places this entity in its own class. Besides the expression of a well-studied oncogenic translocation, ALCL, ALK+ may also have a unique pathogenesis with a thymic origin like T lymphoblastic lymphoma but a peripheral presentation akin to PTCL. This perspective discusses evidence towards the potential origin of ALCL, ALK+, and mechanisms that may give rise to its unique phenotype.

A new era for cutaneous CD30-positive T-cell lymphoproliferative disorders

Cutaneous CD30+ T-cell lymphoproliferative disorders (CD30+ T-LPD) represent a spectrum encompassing lymphomatoid papulosis (LyP), primary cutaneous anaplastic large-cell lymphoma (pcALCL) and borderline lesions. They share the expression of CD30 as a common phenotypic marker. They differ however in their clinical presentation, the histological features and clinical course. Moreover, LyP and PcALCL show numerous clinical, histological and phenotypic variants. Overlapping features of LyP and pcALCL with themselves and with other cutaneous and systemic lymphomas emphasize the importance of careful clinicopathologic correlation and staging in the diagnosis of CD30+ T-LPD. Furthermore, an increasing number of inflammatory and infectious skin disorders harboring medium-sized to large CD30+ cells have to be considered in the differential diagnosis. Whereas the expression of CD30 in cutaneous CD30+ T-LPD stands for a favourable prognosis, its expression in other cutaneous and systemic lymphomas has a divergent impact. The assessment of CD30 expression does not only provide prognostic information, but is of potential therapeutic relevance as CD30 can serve as a therapeutic target. This review focuses on the clinicopathological and phenotypic spectrum of CD30+ T-LPD, its differential diagnoses and the role of CD30 as a diagnostic, prognostic and therapeutic marker.

CD30 Induces Heat Shock Protein 90 and Signal Integration in Classic Hodgkin Lymphoma Cells

Previous studies report deregulation of multiple signaling pathways in classic Hodgkin lymphoma (cHL) cells. However, the mechanisms of how these pathways are integrated are not fully understood. Herein, we show involvement of cHL hallmark antigen CD30 in this process. CD30 facilitates phosphorylation of heat shock factor 1, activates heat shock promoter element, and induces heat shock protein (HSP) 90. CD30 repression and subsequent inhibition of HSP90 suppresses NF-κB, extracellular signal-regulated kinase, AKT, and STAT pathways in cHL cell lines. Thus, CD30-mediated induction of HSP90 appears to serve as a central hub for integration of intracellular signaling in cHL cells. We also show that CD30 induces HSP90 through phosphorylation of heat shock factor 1 via c-Jun N-terminal kinase in cHL cells. Although anaplastic large-cell lymphoma (ALCL) also is associated with CD30 overexpression, our experiments reveal that HSP90 induction in ALCL-bearing nucleophosmin-anaplastic lymphoma kinase (ALK) does not depend on CD30 but instead on ALK via c-Jun N-terminal kinase. Together, these results highlight a novel role for CD30 in mediating integration of signaling pathways of cHL cells while being replaced in this function by ALK in ALCL cells.

Molecular genetics of childhood, adolescent and young adult non-Hodgkin lymphoma

Molecular genetic abnormalities are ubiquitous in non-Hodgkin lymphoma (NHL), but genetic changes are not yet used to define specific lymphoma subtypes. Certain recurrent molecular genetic abnormalities in NHL underlie molecular pathogenesis and/or are associated with prognosis or represent potential therapeutic targets. Most molecular genetic studies of B- and T-NHL have been performed on adult patient samples, and the relevance of many of these findings for childhood, adolescent and young adult NHL remains to be demonstrated. In this review, we focus on NHL subtypes that are most common in young patients and emphasize features actually studied in younger NHL patients. This approach highlights what is known about NHL genetics in young patients but also points to gaps that remain, which will require cooperative efforts to collect and share biological specimens for genomic and genetic analyses in order to help predict outcomes and guide therapy in the future.

Primary nodal peripheral T-cell lymphomas: diagnosis and therapeutic considerations

Nodal peripheral T-cell lymphomas are a rare group of neoplasms derived from post-thymic and activated T lymphocytes. A review of scientific articles listed in PubMed, Lilacs, and the Cochrane Library databases was performed using the term “peripheral T-cell lymphomas”. According to the World Health Organization classification of hematopoietic tissue tumors, this group of neoplasms consists of peripheral T-cell lymphoma not otherwise specified (PTCL-NOS), angioimmunoblastic T-cell lymphoma (AITL), anaplastic large cell lymphoma-anaplastic lymphoma kinase positive (ALCL-ALK⁺), and a provisional entity called anaplastic large cell lymphoma-anaplastic lymphoma kinase negative (ALCL-ALK⁻). Because the treatment and prognoses of these neoplasms involve different principles, it is essential to distinguish each one by its clinical, immunophenotypic, genetic, and molecular features. Except for anaplastic large cell lymphoma-anaplastic lymphoma kinase positive, which has no adverse international prognostic index, the prognosis of nodal peripheral T-cell lymphomas is worse than that of aggressive B-cell lymphomas. Chemotherapy based on anthracyclines provides poor outcomes because these neoplasms frequently have multidrug-resistant phenotypes. Based on this, the current tendency is to use intensified cyclophosphamide, doxorubicin, vincristine, prednisolone (CHOP) regimens with the addition of new drugs, and autologous hematopoietic stem cell transplantation. This paper describes the clinical features and diagnostic methods, and proposes a therapeutic algorithm for nodal peripheral T-cell lymphoma patients.

Successful use of brentuximab vedotin for refractory anaplastic large cell lymphoma as a bridging therapy to haploidentical stem cell transplantation and maintenance therapy post-transplantation

Brentuximab vedotin (BV) is a monoclonal antibody-drug conjugate that targets CD30, and has been reported to be effective for relapsed/refractory anaplastic large cell lymphoma. We here report a patient who experienced multiple relapses after conventional chemotherapy and autologous hematopoietic stem cell transplantation (HSCT). He achieved a complete metabolic response with BV and proceeded to undergo haploidentical HSCT. After HSCT, he received three doses of BV to prevent an early relapse, and remains in remission 16 months post-transplantation. Our case suggests the potential use of BV both as a bridging therapy to allogeneic HSCT and as a maintenance therapy post-transplantation.

Essential role of IRF4 and MYC signaling for survival of anaplastic large cell lymphoma

IRF4 regulates MYC expression in ALCL. ALCL survival depends on IRF4/MYC signaling.

Cutaneous CD30-Positive Lymphoproliferative Disorders

Cutaneous CD30+ lymphoproliferative disorders are the second most common types of cutaneous T-cell lymphomas. They represent a well-defined spectrum encompassing lymphomatoid papulosis (LyP), primary cutaneous anaplastic large-cell lymphoma (pcALCL), and borderline lesions. They share the expression of CD30 as a common phenotypic hallmark, but they differ in their clinical presentation, course, and histologic features. New variants have been recently identified, including CD8+ epidermotropic LyP type D, angioinvasive LyP type E, and ALK-positive pcALCL. This review describes clinical, histopathologic, and phenotypic variants; their differential diagnoses (benign and malignant); and the role of CD30 as a diagnostic, prognostic, and therapeutic marker.

Anaplastic large cell lymphoma involving anterior segment of the eye

A 36-year-old woman was diagnosed with anaplastic large cell lymphoma (ALCL) by excisional biopsy of a left frontal skin lesion. During the first cycle of chemotherapy (cyclophosphamide, doxorubicin, vincristine, and prednisolone), the patient complained of right ocular pain and inflammation. Cytologic examination using aqueous humor revealed atypical lymphocytes, suggesting intraocular ALCL involvement. Acute angle closure developed in the anterior chamber due to rapid progression of ALCL, causing pupillary block. Laser and surgical interventions were attempted but failed to relieve the pupillary block. Finally, radiation therapy resolved the pupillary block to restore the anterior chamber and normalize intraocular pressure. This is the first case in the English literature of ALCL involving the iris to cause acute secondary angle closure.

Beyond NPM-anaplastic lymphoma kinase driven lymphomagenesis: alternative drivers in anaplastic large cell lymphoma

PURPOSE OF REVIEW

Anaplastic large cell lymphomas (ALCLs) are rare entities whose somatic genetic lesions have been identified only in a subset of patients. Thus, an integrated and massive discovery programme is required to define their tumourigenic alterations and to design more successful tailored therapies.

RECENT FINDINGS

The discovery of anaplastic lymphoma kinase (ALK) fusions has provided the basis for the characterization of distinct subsets among ALCL patients. Although the oncogenic addiction of ALK signalling is proven, the tumorigenic contribution of coactivating lesions is still missing. As ALK- and ALK+ share common signatures, it is plausible that analogous mechanisms of transformation may be operating in both subsets, as confirmed by the dysregulated activation of c-MYC, RAS and NFκB, and the loss of Blimp-1 and p53/p63 axis. Nonetheless, recurrent genetic alterations for ALK- ALCL or refractory leukaemic ALK+ ALCL are lacking. Moreover, although conventional chemotherapies (anthracycline-based) are most successful, that is in ALK+ ALCL patients, the implementation of ALK inhibitors or of anti-CD30 based treatments provides innovative solutions, particularly in paediatric ALK+ ALCL and in chemorefractory/relapsed patients.

SUMMARY

The complete portrayal of the landscape of genetic alterations in ALCL will dictate the development of innovative chemotherapeutic and targeted therapies that will fit most with the molecular and clinical profiling of individual patients.

PRDM1/BLIMP1 is commonly inactivated in anaplastic large T-cell lymphoma

The commonest lesions in anaplastic large cell lymphomas are losses at 17p13 and at 6q21, concomitant in up to one-quarter of the cases. PRDM1 (BLIMP1) gene (6q21) is inactivated by multiple mechanisms and acts as a tumor suppressor gene in anaplastic large B-cell lymphoma.

STAT3-mediated activation of microRNA cluster 17~92 promotes proliferation and survival of ALK-positive anaplastic large cell lymphoma

Systemic anaplastic large cell lymphoma is a category of T-cell non-Hodgkin's lymphoma which can be further subdivided into two distinct entities (ALK(+) and ALK(-)) based on the presence or absence of ALK gene rearrangements. Among several pathways triggered by ALK signaling, constitutive activation of STAT3 is strictly required for ALK-mediated transformation and survival. Here we performed genome-wide microRNA profiling and identified 48 microRNA concordantly modulated by the inducible knock-down of ALK and STAT3. To evaluate the functional role of differentially expressed miRNA, we forced their expression in ALK(+) anaplastic large cell lymphoma cells, and monitored their influence after STAT3 depletion. We found that the expression of the microRNA-17~92 cluster partially rescues STAT3 knock-down by sustaining proliferation and survival of ALK(+) cells. Experiments in a xenograft mouse model indicated that forced expression of microRNA-17~92 interferes with STAT3 knock-down in vivo. High expression levels of the microRNA-17~92 cluster resulted in down-regulation of BIM and TGFβRII proteins, suggesting that their targeting might mediate resistance to STAT3 knock-down in anaplastic large cell lymphoma cells. We speculate that the microRNA-17~92 cluster is involved in lymphomagenesis of STAT3(+) ALCL and that its inhibition might represent an alternative avenue to interfere with ALK signaling in anaplastic large cell lymphomas.

MicroRNA expression profiling identifies molecular signatures associated with anaplastic large cell lymphoma

Anaplastic large-cell lymphomas (ALCLs) encompass at least 2 systemic diseases distinguished by the presence or absence of anaplastic lymphoma kinase (ALK) expression. We performed genome-wide microRNA (miRNA) profiling on 33 ALK-positive (ALK[+]) ALCLs, 25 ALK-negative (ALK[-]) ALCLs, 9 angioimmunoblastic T-cell lymphomas, 11 peripheral T-cell lymphomas not otherwise specified (PTCLNOS), and normal T cells, and demonstrated that ALCLs express many of the miRNAs that are highly expressed in normal T cells with the prominent exception of miR-146a. Unsupervised hierarchical clustering demonstrated distinct clustering of ALCL, PTCL-NOS, and the AITL subtype of PTCL. Cases of ALK(+) ALCL and ALK(-) ALCL were interspersed in unsupervised analysis, suggesting a close relationship at the molecular level. We identified an miRNA signature of 7 miRNAs (5 upregulated: miR-512-3p, miR-886-5p, miR-886-3p, miR-708, miR-135b; 2 downregulated: miR-146a, miR-155) significantly associated with ALK(+) ALCL cases. In addition, we derived an 11-miRNA signature (4 upregulated: miR-210, miR-197, miR-191, miR-512-3p; 7 downregulated: miR-451, miR-146a, miR-22, miR-455-3p, miR-455-5p, miR-143, miR-494) that differentiates ALK(-) ALCL from other PTCLs. Our in vitro studies identified a set of 32 miRNAs associated with ALK expression. Of these, the miR-17∼92 cluster and its paralogues were also highly expressed in ALK(+) ALCL and may represent important downstream effectors of the ALK oncogenic pathway.

Successful treatment in a child with anaplastic large cell lymphoma and coexistence of pulmonary tuberculosis

A 13-year-old girl was admitted to our department with a history of severe pain of her left axilla and fever. On physical examination, a block of lymph nodes in her left axilla, diffuse papular rash, and red-violet swelling of her supraclavicular and subclavian region were noted. Imaging investigations revealed left axillar and supraclavicular lymphadenopathy and a small nodular shade in the upper lobe of her left lung. A biopsy from an axillary lymph node established the diagnosis of anaplastic large cell lymphoma (ALCL), whereas DNA of Mycobacterium tuberculosis was detected by polymerase chain reaction (PCR) in the same tissue biopsy. Patient was started on chemotherapy for ALCL and achieved remission of all initially involved fields. Nevertheless, two new nodular lesions were detected in the left lower lobe. Biopsy revealed granulomas, and PCR was positive for M. tuberculosis. Our patient received treatment with the combination of isoniazid and rifampin (12 months), pyrazinamide (the first 2 months), and maintenance chemotherapy for her ALCL for one year simultaneously. Four years later, she is disease free for both mycobacterial infection and lymphoma. We are reporting this successful management of mycobacterial infection in a patient with ALCL despite intensive chemotherapy that the patient received at the same time.

Expression of AEG-1 in human T-cell lymphoma enhances the risk of progression

The aim of this study was to examine the expression and role of astrocyte elevated gene-1 (AEG-1) in biological processes of T-cell non-Hodgkin's lymphoma (T-NHL). AEG-1 expression in T-NHL patients was characterized with immunohistochemistry. The expression of AEG-1, survivin, Bcl-2 and Bax in Jurkat and Hut-78 cells was detected by real-time PCR and western blotting. Cell proliferation, cell cycle and apoptosis were measured by MTT and flow cytometry. MMP-2/-9 activity was detected by gelatin zymography. Of the studied tumors, 104 (80.62%) exhibited cytoplasmic AEG-1 immunostaining. AEG-1-siRNA in Jurkat and Hut-78 cells suppressed cell proliferation and induced cell apoptosis, inhibited survivin and Bcl-2/Bax protein expression as well as MMP-2/-9 activity. Downregulation of AEG-1 using siRNA could provide a potential approach for gene therapy against T-NHL, and the antitumor effects may be associated with inhibition of survivin and Bcl-2/Bax protein expression and MMP-2/-9 activity.

Small nucleolar RNA expression profiling identifies potential prognostic markers in peripheral T-cell lymphoma

Peripheral T-cell lymphoma (PTCL) is a rare, heterogeneous type of non-Hodgkin lymphoma (NHL) that, in general, is associated with a poor clinical outcome. Therefore, a current major challenge is the discovery of new prognostic tools for this disease. In the present study, a cohort of 122 patients with PTCL was collected from a multicentric T-cell lymphoma consortium (TENOMIC). We analyzed the expression of 80 small nucleolar RNAs (snoRNAs) using high-throughput quantitative PCR. We demonstrate that snoRNA expression analysis may be useful in both the diagnosis of some subtypes of PTCL and the prognostication of both PTCL-not otherwise specified (PTCL-NOS; n = 26) and angio-immunoblastic T-cell lymphoma (AITL; n = 46) patients treated with chemotherapy. Like miRNAs, snoRNAs are globally down-regulated in tumor cells compared with their normal counterparts. In the present study, the snoRNA signature was robust enough to differentiate anaplastic large cell lymphoma (n = 32) from other PTCLs. For PTCL-NOS and AITL, we obtained 2 distinct prognostic signatures with a reduced set of 3 genes. Of particular interest was the prognostic value of HBII-239 snoRNA, which was significantly over-expressed in cases of AITL and PTCL-NOS that had favorable outcomes. Our results suggest that snoRNA expression profiles may have a diagnostic and prognostic significance for PTCL, offering new tools for patient care and follow-up.

Histone acetylation and DNA demethylation of T cells result in an anaplastic large cell lymphoma-like phenotype

A characteristic feature of anaplastic large cell lymphoma is the significant repression of the T-cell expression program despite its T-cell origin. The reasons for this down-regulation of T-cell phenotype are still unknown. To elucidate whether epigenetic mechanisms are responsible for the loss of the T-cell phenotype, we treated anaplastic large cell lymphoma and T-cell lymphoma/leukemia cell lines (n=4, each) with epigenetic modifiers to evoke DNA demethylation and histone acetylation. Global gene expression data from treated and untreated cell lines were generated and selected, and differentially expressed genes were evaluated by real-time reverse transcriptase polymerase chain reaction and western blot analysis. Additionally, histone H3 lysine 27 trimethylation was analyzed by chromatin immunoprecipitation. Combined DNA demethylation and histone acetylation of anaplastic large cell lymphoma cells was not able to reconstitute their T-cell phenotype. Instead, the same treatment induced in T cells: (i) an up-regulation of anaplastic large cell lymphoma-characteristic genes (e.g. ID2, LGALS1, c-JUN), and (ii) an almost complete extinction of their T-cell phenotype including CD3, LCK and ZAP70. In addition, suppressive trimethylation of histone H3 lysine 27 of important T-cell transcription factor genes (GATA3, LEF1, TCF1) was present in anaplastic large cell lymphoma cells, which is in line with their absence in primary tumor specimens as demonstrated by immunohistochemistry. Our data suggest that epigenetically activated suppressors (e.g. ID2) contribute to the down-regulation of the T-cell expression program in anaplastic large cell lymphoma, which is maintained by trimethylation of histone H3 lysine 27.

NPM-ALK: The Prototypic Member of a Family of Oncogenic Fusion Tyrosine Kinases

Anaplastic lymphoma kinase (ALK) was first identified in 1994 with the discovery that the gene encoding for this kinase was involved in the t(2;5)(p23;q35) chromosomal translocation observed in a subset of anaplastic large cell lymphoma (ALCL). The NPM-ALK fusion protein generated by this translocation is a constitutively active tyrosine kinase, and much research has focused on characterizing the signalling pathways and cellular activities this oncoprotein regulates in ALCL. We now know about the existence of nearly 20 distinct ALK translocation partners, and the fusion proteins resulting from these translocations play a critical role in the pathogenesis of a variety of cancers including subsets of large B-cell lymphomas, nonsmall cell lung carcinomas, and inflammatory myofibroblastic tumours. Moreover, the inhibition of ALK has been shown to be an effective treatment strategy in some of these malignancies. In this paper we will highlight malignancies where ALK translocations have been identified and discuss why ALK fusion proteins are constitutively active tyrosine kinases. Finally, using ALCL as an example, we will examine three key signalling pathways activated by NPM-ALK that contribute to proliferation and survival in ALCL.

Clinical and laboratory characteristics of systemic anaplastic large cell lymphoma in Chinese patients

Background

Systemic anaplastic large cell lymphoma (S-ALCL) is a rare disease with a highly variable prognosis and no standard chemotherapy regimen. Anaplastic lymphoma kinase (ALK) has been reported as an important prognostic factor correlated with S-ALCL in many but not all studies. In our study, we retrospectively analyzed 92 patients with S-ALCL from the Peking University Lymphoma Center for clinical and molecular prognostic factors to make clear the role of ALK and other prognostic factors in Han Chinese S-ALCL.

Results

The majority of Chinese S-ALCL patients were young male patients (median age 26, male/female ratio 1.7) and the median age was younger than previous reports regardless of ALK expression status. The only statistically significant different clinical characteristic in S-ALCL between ALK positive (ALK⁺) and ALK negative (ALK^-) was age, with a younger median age of 22 for ALK⁺ compared with 30 for ALK^-. However, when pediatric patients (≤18) were excluded, there was no age difference between ALK⁺ and ALK^-. The groups did not differ in the proportion of males, those with clinical stage III/IV (49 vs 51%) or those with extranodal disease (53 vs 59%). Of 73 evaluable patients, the 3-year and 5-year survival rates were 60% and 47%, respectively. Univariate analysis showed that three factors: advanced stage III/IV, lack of expression of ALK, and high Ki-67 expression, were associated with treatment failure in patients with S-ALCL. However, ALK expression correlated with improved survival only in patients younger than 14 years, while not in adult patients. In multivariate analysis, only clinical stage was an independent prognostic factor for survival. Expressions of Wilms tumor 1 (WT1) and B-cell lymphoma 2 protein (BCL-2) correlated with the expression of ALK, but they did not have prognostic significance. High Ki-67 expression was also a poor prognostic factor.

Conclusions

Our results show that ALK expression alone is not sufficient to determine the outcome of ALCL and other prognostic factors must be considered. Clinical stage is an independent prognostic factor. Ki-67 expression is a promising prognostic factor.

Anaplastic large cell lymphoma: an unusual presentation in a 7-year-old girl

Anaplastic large cell lymphoma (ALCL) accounts for 10% to 30% of all childhood lymphomas and approximately 5% of all non-Hodgkin's lymphoma. ALCL is considered to be a T-cell non-Hodgkin's lymphoma that can be divided into two major groups with distinct genetic, immunophenotypic, and clinical behaviors. The first group consists of a spectrum of CD30+ T-cell lymphoproliferative disorders that include primary cutaneous ALCL (C-ALCL) and lymphomatoid papulosis. The second group is systemic ALCL (S-ALCL), which is further divided into two subgroups: anaplastic lymphoma kinase positive (ALK+) and ALK-negative. Between 30% and 60% of S-ALCL express ALK, which is usually the result of a t(2;5) translocation that correlates with onset in the first three decades of life, male predominance, and good prognosis. Although morphologically similar, ALK- ALCL shows varied clinical behaviors and immunophenotypes; is commonly seen in older age groups, with a peak incidence in the sixth decade of life with no preference as to sex; and has an overall poorer prognosis. We present a case of CD30+, ALK- S-ALCL in a 7-year-old girl.

Identification of a 3-gene model as a powerful diagnostic tool for the recognition of ALK-negative anaplastic large-cell lymphoma

Anaplastic large-cell lymphomas (ALCLs) are a group of clinically and biologically heterogeneous diseases including the ALK(+) and ALK(-) systemic forms. Whereas ALK(+) ALCLs are molecularly characterized and can be readily diagnosed, specific immunophenotypic or genetic features to define ALK(-) ALCL are missing, and their distinction from other T-cell non-Hodgkin lymphomas (T-NHLs) remains controversial. In the present study, we undertook a transcriptional profiling meta-analysis of 309 cases, including ALCL and other primary T-NHL samples. Pathway discovery and prediction analyses defined a minimum set of genes capable of recognizing ALK(-) ALCL. Application of quantitative RT-PCR in independent datasets from cryopreserved and formalin-fixed paraffin-embedded samples validated a 3-gene model (TNFRSF8, BATF3, and TMOD1) able to successfully separate ALK(-) ALCL from peripheral T-cell lymphoma not otherwise specified, with overall accuracy near 97%. In conclusion, our data justify the possibility of translating quantitative RT-PCR protocols to routine clinical settings as a new approach to objectively dissect T-NHL and to select more appropriate therapeutic protocols.

Genetic alterations in systemic nodal and extranodal non-cutaneous lymphomas derived from mature T cells and natural killer cells

Mature (peripheral) T-cell and natural killer (NK)-cell lymphomas comprise a series of rather different neoplasms. Based on morphologic, immunophenotypic, genetic, and clinical data, the World Health Organization classification recognizes more than 20 entities or provisional entities. The variable clinical presentations, the objective recognition and pathological stratification, the difficulties regarding treatment, and the hardly predictable response to therapy indicate that the management of these entities requires novel tools. In contrast to B-cell lymphomas or precursor T-cell neoplasms, few recurrent translocations have been identified so far in T-cell non-Hodgkin's and NK-cell lymphomas. Additionally, some of the entities recognized by the World Health Organization classification are very rare and very scarce molecular data are available for T-cell lymphomas. Here, we have reviewed published reports focusing on the genetic lesions and gene expression profiling underlying systemic nodal and extranodal non-cutaneous mature T-cell and NK-cell lymphomas. We also provide a summary of new agents in clinical development and outline some future directions.

An algorithmic approach to the diagnosis of NK and T cell lymphomas

Lymphomas of natural killer (NK) and T cell lineages are uncommon disorders, although as a group they are more usually encountered in Asia compared to Western populations. In part due to their rarity, diagnosis and classification of T cell lymphomas often pose a challenge to clinicians and pathologists. Although there are morphological features that are characteristic of certain subtypes, correct classification of NK and T cell neoplasms relies heavily on the immunophenotype. With few exceptions, non-random genetic alterations such as translocations are less often seen in T cell neoplasms, adding to the diagnostic difficulty. Given these limitations, pathological diagnosis and classification of NK and T cell lymphomas are anything but straightforward. This paper attempts to present a practical algorithmic approach for the general pathologist who is confronted with these neoplasms.

Clonal T-cell receptor β-chain gene rearrangements in differential diagnosis of lymphomatoid papulosis from skin metastasis of nodal anaplastic large-cell lymphoma

BACKGROUND

In patients with a history of nodal anaplastic large-cell lymphoma (ALCL), differentiation of type C lymphomatoid papulosis from cutaneous involvement of systemic ALCL may be challenging because the 2 entities may exhibit identical histologic features. Although metastatic ALCL generally carries the same clone as the primary lymphoma, expression of a distinct clone likely represents a distinct process.

OBSERVATIONS

A 54-year-old white man had a history of anaplastic lymphoma kinase 1-negative ALCL in the right inguinal lymph node 6 years ago. A complete response was achieved after 6 cycles of CHOP (cyclophosphamide, doxorubicin, vincristine [Oncovin], and prednisone administered in 21-day cycles) and radiation therapy. After 3½ years, the patient observed waxing and waning papules and nodules. Examination of the biopsy specimen revealed a dense CD30(+) lymphocytic infiltrate; no evidence of systemic malignancy was evident on positron emission tomography. Although clinically the presentation was consistent with lymphomatoid papulosis, metastatic ALCL had to be excluded. Polymerase chain reaction analysis with T-cell receptor γ-chain gene rearrangement (TCR-γR) was performed on the original lymph node and new skin lesions. Results of the TCR-γR analysis were positive for clonality in both lesions. However, separate clonal processes were identified. The identification of distinct clones supported the clinical impression of lymphomatoid papulosis.

CONCLUSION

Polymerase chain reaction analysis of TCR-γR is a useful method for distinguishing different clonal processes and is recommended when differentiation of primary and secondary lymphoproliferative disorders is required.

Anaplastic lymphoma kinase in human cancer

The receptor tyrosine kinases (RTKs) play a critical role, controlling cell proliferation, survival, and differentiation of normal cells. Their pivotal function has been firmly established in the pathogenesis of many cancers as well. The anaplastic lymphoma kinase (ALK), a transmembrane RTK, originally identified in the nucleophosmin (NPM)-ALK chimera of anaplastic large cell lymphoma, has emerged as a novel tumorigenic player in several human cancers. In this review, we describe the expression of the ALK-RTK, its related fusion proteins, and their molecular mechanisms of activation. Novel tailored strategies are briefly illustrated for the treatment of ALK-positive neoplasms.

Novel therapeutic options in anaplastic large cell lymphoma: molecular targets and immunological tools

Anaplastic large cell lymphoma (ALCL) is a CD30-positive, aggressive T-cell lymphoma, and about half of the patients with this disease harbor the t(2;5)(p21;q35) translocation. This chromosomal aberration leads to fusion of the NPM gene with the ALK tyrosine kinase, leading to its constitutive activation. To date, treatment options include polychemotherapy (e.g., cyclophosphamide, doxorubicin, vincristine, and prednisone), which is sometimes combined with radiation in the case of bulky disease, leading to remission rates of ∼80%. However, the remaining patients do not respond to therapy, and some patients experience chemo-resistant relapses, making the identification of new and better treatments imperative. The recent discovery of deregulated ALK in common cancers such as non-small cell lung cancer and neuroblastoma has reinvigorated industry interest in the development of ALK inhibitors. Moreover, it has been shown that the ALK protein is an ideal antigen for vaccination strategies due to its low expression in normal tissue. The characterization of microRNAs that are deregulated in ALCL will yield new insights into the biology of ALCL and open new avenues for therapeutic approaches in the future. Also, CD30 antibodies that have been tested in ALCL for quite a while will probably find a place in forthcoming treatment strategies.

Cutaneous anaplastic large-cell lymphoma should be evaluated for systemic involvement regardless of ALK-1 status: case reports and review of literature

Anaplastic large-cell lymphoma (ALCL) is a lymphoma that expresses CD30. Cutaneous ALCL presents either as primary cutaneous disease or as secondary skin involvement due to the systemic disease. Herein, we describe two patients who presented to dermatology for evaluation of skin lesions diagnosed by non-dermatologists as a cutaneous abscess and lupus erythematosus, respectively. Upon investigation by a team of medical dermatologists and dermatopathologists, systemic ALCL with secondary skin involvement was discovered in both patients. The majority of cases of systemic ALCL with cutaneous involvement express anaplastic lymphoma kinase-1 (ALK-1), and are associated with a more favorable prognosis than ALK-1-negative cases. However, cutaneous ALCL regardless of ALK-1 status may be secondary to systemic lymphoma. This article stresses the importance of dermatologists being aware of the diagnosis of systemic lymphoma based on cutaneous findings, and being aggressive in initiating appropriate diagnostic testing. Primary cutaneous ALCL and systemic ALCL are reviewed.

Pathobiology of anaplastic large cell lymphoma

The authors revise the concept of anaplastic large cell lymphoma (ALCL) in the light of the recently updated WHO classification of Tumors of Hematopoietic and Lymphoid Tissues both on biological and clinical grounds. The main histological findings are illustrated with special reference to the cytological spectrum that is indeed characteristic of the tumor. The phenotype is reported in detail: the expression of the ALK protein as well as the chromosomal abnormalities is discussed with their potential pathogenetic implications. The clinical features of ALCL are presented by underlining the difference in terms of response to therapy and survival between the ALK-positive and ALK-negative forms. Finally, the biological rationale for potential innovative targeted therapies is presented.

Anaplastic large cell lymphoma: twenty-five years of discovery

CONTEXT

The year 2010 commemorates the 25th year since the seminal publication by Karl Lennert and Harald Stein and others in Kiel, West Germany, describing an unusual large cell lymphoma now known as anaplastic large cell lymphoma (ALCL). Investigators at many universities and hospitals worldwide have contributed to our current in-depth understanding of this unique peripheral T-cell lymphoma, which in its systemic form, principally occurs in children and young adults.

OBJECTIVE

To summarize our current knowledge of the clinical and pathologic features of systemic and primary cutaneous ALCL. Particular emphasis is given to the biology and pathogenesis of ALCL.

DATA SOURCES

Search of the medical literature (Ovid MEDLINE In-Process & Other Non-Indexed Citations and Ovid MEDLINE: 1950 to Present [National Library of Medicine]) and more than 20 years of diagnostic experience were used as the source of data for review.

CONCLUSIONS

Based on immunostaining for activation antigen CD30 and the presence of dysregulation of the anaplastic lymphoma kinase gene (2p23), the diagnosis of ALCL has become relatively straightforward for most patients. Major strides have been made during the last decade in our understanding of the complex pathogenesis of ALCL. Constitutive NPM-ALK signaling has been shown to drive oncogenesis via an intricate network of redundant and interacting pathways that regulate cell proliferation, cell fate, and cytoskeletal modeling. Nevertheless, pathomechanistic, therapeutic, and diagnostic challenges remain that should be resolved as we embark on the next generation of discovery.

CD13+ anaplastic large cell lymphoma with leukemic presentation and additional chromosomal abnormality

Anaplastic large cell lymphoma (ALCL) is a highly malignant neoplasm characterized by pleomorphic appearance, different immunophenotypes and variable sites of involvement. Expression of myeloid-associated markers in anaplastic large cell lymphomas may mislead the medical team and result in delay of diagnosis due to unusual phenotype. It is important to diagnose this type of tumors and distinguish it from myeloid neoplasms (extramedullary myeloid cell tumors and histiocytic tumors) since therapy and prognosis are significantly different.A 16-year-old female patient presented with fever, lymphadenopathy, and high white blood cell count. Diagnosing a CD13+ ALCL with leukemic presentation with additional cytogenetic abnormality (duplication 5q35) was a significant diagnostic challenge.This combination of features, unusual for lymphoma, should be considered in differential diagnosis of myeloid neoplasms and fatal infections.