Treatment algorithms for mature T-cell and natural killer-cell neoplasms

Immunologic Milieu of Mature T-Cell and NK-Cell Lymphomas-Implications for Therapy

PURPOSE OF THE REVIEW

T-cells and natural killer (NK) cells share the same ontogeny, and lymphomas derived from them are clinically diverse, occurring in nodal and extranodal sites. In addition to inherent properties of these lymphomas, their microenvironment also impacts on pathogenesis and response to therapy. An understanding of the milieu of T-cell and NK cell lymphomas has important implications on treatment.

RECENT FINDINGS

Components of the microenvironment include tumour-associated macrophages (TAM), non-neoplastic T-cells and B-cells, eosinophils, dendritic cells, endothelial cells and blood vessels. TAM typically undergoes M2 polarization, promoting angiogenesis and inhibiting anti-tumour cellular immunity. In lymphomas of follicular helper T-cell derivation, increased B-cell proliferation occurs, which may in turn enhance neoplastic T-cell growth. The expression of immune checkpoint ligands on TAM, dendritic cells or lymphoma cells induces an immunosuppressive environment conducive to neoplastic proliferation. Strategies against this complex cellular and immunologic microenvironment have shown promises. These include the use of signal transduction inhibitors, monoclonal antibodies against chemokines or non-neoplastic microenvironmental cells, immunomodulatory drugs and immune checkpoint blockade. As T-cell and NK cell lymphomas are highly heterogeneous, clinical trials to demonstrate efficacy of a given therapeutic approach requires careful design aiming at enriching patient populations who will best respond. Targeting of the immunologic milieu in T-cell and NK-cell lymphomas offers exciting challenges and opportunities.

CD56-Negative Aggressive NK Cell Leukemia Relapsing as Multiple Cranial Nerve Palsies: Case Report and Literature Review

Background

Aggressive natural killer cell leukemia (ANKL) is extremely rare and habitually manifests as a systemic disease with multiorgan failure that rapidly evolves to death. The neoplastic natural killer (NK) cells usually harbor the Epstein-Barr virus (EBV) with a latent viral infection pattern type II; they often have a cytoplasmic CD3ε⁺ and surface CD3⁻, CD2⁺, and CD56⁺ immunophenotype, and they show complex genetic abnormalities affecting multiple tumor suppressor genes and oncogenes. We present a rare case of CD56-negative ANKL and review the clinical and laboratorial criteria for the diagnosis, as well as the available therapies.

Case Presentation

A European 36-year-old male presented with acute onset fever, pallor, weakness, and jaundice. He had hepatosplenomegaly, severe pancytopenia, hepatic cytolysis, and very high serum lactic dehydrogenase levels. The bone marrow studies resulted in the diagnosis of an EBV-positive, CD56-negative ANKL. The patient failed to respond to gemcitabine and cisplatin-based polychemotherapy, dying three months later with leukemic meningitis and multiple cranial nerves palsies.

Conclusions

The diagnosis of ANKL is difficult and requires both clinical suspicion and an extensive laboratorial approach. Absence of CD56 expression on the neoplastic NK cells may impose difficulties in the diagnosis, which requires morphological, immunophenotypic, histopathological, immunohistochemical, cytogenetic, and molecular studies.

Pitfalls and major issues in the histologic diagnosis of peripheral T-cell lymphomas: results of the central review of 573 cases from the T-Cell Project, an international, cooperative study

Peripheral T-cell lymphomas (PTCLs) comprise a heterogeneous group of neoplasms that are derived from post-thymic lymphoid cells at different stages of differentiation with different morphological patterns, phenotypes and clinical presentations. PTCLs are highly diverse, reflecting the diverse cells from which they can originate and are currently sub-classified using World Health Organization (WHO) 2008 criteria. In 2006 the International T-Cell Lymphoma Project launched the T-Cell Project, building on the retrospective study previously carried on by the network, with the aim to prospectively collect accurate data to improve knowledge on this group of lymphomas. Based on previously published reports from International Study Groups it emerged that rendering a correct classification of PTCLs is quite difficult because the relatively low prevalence of these diseases results in a lack of confidence by most pathologists. This is the reason why the T-Cell Project requested the availability of diagnostic material from the initial biopsy of each patient registered in the study in order to have the initial diagnosis centrally reviewed by expert hematopathologists. In the present report the results of the review process performed on 573 cases are presented. Overall, an incorrect diagnosis was centrally recorded in 13.1% cases, including 8.5% cases centrally reclassified with a subtype eligible for the project and 4.6% cases misclassified and found to be disorders other than T-cell lymphomas; 2.1% cases were centrally classified as T-Cell disorders not included in the study population. Thus, the T-Cell Project confirmed the difficulties in providing an accurate classification when a diagnosis of PTCLs is suspected, singled out the major pitfalls that can bias a correct histologic categorization and confirmed that a centralized expert review with the application of adequate diagnostic algorithms is mandatory when dealing with these tumours. Copyright © 2016 John Wiley & Sons, Ltd.

Aggressive mature natural killer cell neoplasms: report on a series of 12 European patients with emphasis on flow cytometry based immunophenotype and DNA content of neoplastic natural killer cells

We report 12 cases of aggressive natural killer (NK) cell neoplasms diagnosed in Portugal, with emphasis on flow cytometry. Ten patients had extranodal NK/T cell lymphoma, nasal type and two had aggressive NK cell leukemia, and seven were men and five were women, with a median age of 50 years. NK cells brightly expressed the CD56 adhesion molecule and CD94 lectin type killer receptor and had an activation-related HLA-DR+ CD45RA+ CD45RO+ immunophenotype, in most cases. In contrast, dim CD16 expression was found in a minor proportion of cases, whereas CD57 and the CD158a and CD158e1 killer immunoglobulin-like receptors were negative. One-third of cases showed a hyperploid DNA content and nearly all had a very high S-phase proliferative rate. The phenotypic features of the neoplastic NK cells would suggest that they represent the transformed counterpart of the CD56 + bright NK cells that circulate in normal blood.

Aggressive mature natural killer cell neoplasms: from epidemiology to diagnosis

Mature natural killer (NK) cell neoplasms are classified by the World Health Organization into NK/T cell lymphoma, nasal type (NKTCL), aggressive NK-cell leukemia (ANKCL) and chronic lymphoproliferative disorders of NK-cells, the latter being considered provisionally. NKTCL and ANKCL are rare diseases, with higher prevalence in Asia, Central and South America. Most NKTCL present extranodal, as a destructive tumor affecting the nose and upper aerodigestive tract (nasal NKTCL) or any organ or tissue (extranasal NKTCL) whereas ANKCL manifests as a systemic disease with multiorgan involvement and naturally evolutes to death in a few weeks. The histopathological hallmark of these aggressive NK-cell tumors is a polymorphic neoplastic infiltrate with angiocentricity, angiodestruction and tissue necrosis. The tumor cells have cytoplasmatic azurophilic granules and usually show a CD45(+bright), CD2(+), sCD3(-), cytCD3epsilon(+), CD56(+bright), CD16(−/+), cytotoxic granules molecules(+) phenotype. T-cell receptor genes are in germ-line configuration. Epstein-Barr virus (EBV) -encoded membrane proteins and early region EBV RNA are usually detected on lymphoma cells, with a pattern suggestive of a latent viral infection type II. Complex chromosomal abnormalities are frequent and loss of chromosomes 6q, 11q, 13q, and 17p are recurrent aberrations. The rarity of the NK-cell tumors limits our ability to standardize the procedures for the diagnosis and clinical management and efforts should be made to encourage multi-institutional registries.

T-cell lymphomas in South america and europe

Peripheral T-cell lymphomas are a group of rare neoplasms originating from clonal proliferation of mature post-thymic lymphocytes with different entities having specific biological characteristics and clinical features. As natural killer cells are closely related to T-cells, natural killer-cell lymphomas are also part of the group. The current World Health Organization classification recognizes four categories of T/natural killer-cell lymphomas with respect to their presentation: disseminated (leukemic), nodal, extranodal and cutaneous. Geographic variations in the distribution of these diseases are well documented: nodal subtypes are more frequent in Europe and North America, while extranodal forms, including natural killer-cell lymphomas, occur almost exclusively in Asia and South America. On the whole, T-cell lymphomas are more common in Asia than in western countries, usually affect adults, with a higher tendency in men, and, excluding a few subtypes, usually have an aggressive course and poor prognosis. Apart from anaplastic lymphoma kinase-positive anaplastic large cell lymphoma, that have a good outcome, other nodal and extranodal forms have a 5-year overall survival of about 30%. According to the principal prognostic indexes, the majority of patients are allocated to the unfavorable subset. In the past, the rarity of these diseases prevented progress in the understanding of their biology and improvements in the efficaciousness of therapy. Recently, international projects devoted to these diseases created networks promoting investigations on T-cell lymphomas. These projects are the basis of forthcoming cooperative, large scale trials to detail biologic characteristics of each sub-entity and to possibly individuate targets for new therapies.