Sylvia Hoeller

Increased programmed death-1+ tumor-infiltrating lymphocytes in classical Hodgkin lymphoma substantiate reduced overall survival

Programmed death-1 (PD-1), a protein that is physiologically expressed by germinal center-associated helper T cells, has an inhibitory function on T-cell activity. The distribution of PD-1+ lymphocytes in the microenvironment of Hodgkin lymphoma is not random and can serve as a diagnostic marker. We measured the number of PD-1+ lymphocytes in Hodgkin lymphoma and correlated it with the remaining background lymphocyte populations and known biological and clinical key data on a tissue microarray platform encompassing 280 cases of classical Hodgkin lymphoma and 3 cases of nodular lymphocyte-predominant Hodgkin lymphoma. Prognostic cutoff scores were determined by receiver operating curve analysis. The number of PD-1+ tumor-infiltrating lymphocytes in 189 evaluable cases was median of 27 and mean of 269 cells/mm(2), being higher in lymphocyte-rich classical Hodgkin lymphoma and lower in the mixed cellularity variant. Rimming of tumor cells by PD-1+ cells was observed in all cases of nodular lymphocyte-predominant Hodgkin lymphoma but only in 1% of classical Hodgkin lymphomas, particularly in lymphocyte-rich and -mixed cellularity variants. Thus, the presence of PD-1+ rosettes around neoplastic cells is typical but not exclusive for nodular lymphocyte-predominant Hodgkin lymphoma because it may be encountered in classical Hodgkin lymphoma. The PD-1+ cell amount was lower in classical Hodgkin lymphoma cases with 9p24 gains (PD-1 ligand 2 locus) and in cases with higher numbers of FOXP3+ regulatory T cells. An increased amount of PD-1+ tumor-infiltrating lymphocytes above the prognostic cutoff score (23 cells/mm(2)) was a stage-independent negative prognostic factor of overall survival as opposed to the number of FOXP3+ regulatory T cells. Along with the latter, PD-1+ cells might represent important lymphoma/host microenvironment modulators.

Epstein-Barr virus–positive diffuse large B-cell lymphoma in elderly patients is rare in Western populations

In the currently published World Health Organization-Classification, the new entity of Epstein-Barr virus-positive diffuse large B-cell lymphoma of the elderly was introduced largely based on findings from East-Asian populations. Little is known about its frequency or characteristics in the West, especially in European populations. Using a tissue microarray approach, we identified 8 out of 258 diffuse large B-cell lymphoma cases fulfilling the World Health Organization criteria of an Epstein-Barr virus-positive diffuse large B-cell lymphoma of the elderly, suggesting an incidence of 3.1% in a European population. The median patient age was 65 years. The highest diagnostic sensitivity was only achieved by EBER in situ hybridization. No correlation between Epstein-Barr virus status and outcome was noted except in latency type 3 lymphomas, which had a very poor survival. Sixty-seven percent of Epstein-Barr virus-positive cases showed the presence of necrosis and 50% expressed the activation marker CD30. However, no morphological or immunohistochemical features reliably distinguished all Epstein-Barr virus-positive diffuse large B-cell lymphoma cases. Thus, to identify these Epstein-Barr virus-positive diffuse large B-cell lymphoma in the elderly, EBER in situ hybridization of all de novo diffuse large B-cell lymphoma cases of patients older than 50 years should be considered. In summary, Epstein-Barr virus-positive diffuse large B-cell lymphoma of the elderly is rare in Europeans older than 50 years. It can only be diagnosed by EBER-ISH, and its precise prognostic role is unclear. Whether routine testing of all diffuse large B-cell lymphoma patients older than 50 years can be recommended depends essentially on its clinical relevance. Future studies are needed to address this question.

Recurrent numerical aberrations of JAK2 and deregulation of the JAK2-STAT cascade in lymphomas.

The Janus kinase 2 (JAK2)-signal transducers and activators of transcription (STAT) pathway plays an important role in hematological malignancies. Mutations and translocations of the JAK2 gene, mapped at 9p24, lead to constitutive activation of JAK2 and its downstream targets. The presence of JAK2 mutations in lymphomas has been addressed in larger cohorts, but there are little systemic data on numerical and structural JAK2 aberrations in lymphoid neoplasms. To study the molecular epidemiology of these aberrations and the consecutive activation of the JAK2-STAT pathway in lymphomas, we examined 527 cases, covering the most common entities, in a tissue microarray by fluorescent in situ hybridization with breakable JAK2 probes, and immunohistochemistry for phosphorylated JAK2 (pJAK2) and its preferred downstream pSTAT3 and pSTAT5. 9p24 gains were detected in 6/17 (35%) primary mediastinal B-cell lymphomas (PMBCLs), 25/77 (33%) Hodgkins lymphomas (HLs), 3/16 (19%) angioimmunoblastic T-cell lymphomas (AILTs) and 1/5 ALK1+ anaplastic large cell lymphomas (ALCLs); breaks were observed only in three cases. pJAK2 expression was most prevalent in PMBCL, peripheral T-cell lymphomas and HL. pSTAT3 predominated in ALCLs, HLs, AILTs, PMBCLs and peripheral T-cell lymphomas. pSTAT5 expression was detected frequently in follicular lymphomas, diffuse large B-cell lymphomas and AILTs. 9p24 gains correlated with increased proportions of tumor cells expressing pJAK2 (P=0.002) and pSTAT3 (P=0.001). In follicular lymphomas, concomitant expression of pJAK2 and pSTAT5 was linked to better prognosis, whereas expression of pSTAT3 in nongerminal center-like diffuse large B-cell lymphomas could identify a patient group with an inferior outcome. Our findings stress that despite the rarity of activating JAK2 mutations in lymphomas, JAK2 is recurrently targeted by numerical, and rarely by structural, genetic aberrations in distinct lymphoma subtypes and that JAK2-STAT pathway may play a role in lymphomagenesis.

Diagnostic and Prognostic Utility of PD-1 In B Cell Lymphomas

Aims: Programmed death-1 (PD-1) is expressed by germinal center-associated helper T-cells and acts as a negative regulator of the immune system. PD-1 is encountered on tumor cells of angioimmunoblastic T-cell lymphoma and is a postulated diagnostic marker in chronic lymphocytic leukemia (CLL/SLL). Recent data suggest prognostic importance of PD-1 in follicular lymphoma (FL). We assessed the diagnostic potential and the prognostic importance of PD-1 in B-cell lymphomas. Methods: Distribution of PD-1+ lymphocytes in B-cell lymphomas was studied on 403 cases. Correlation with known biologic and clinical key data was performed. Prognostic cut-off scores were determined by receiver operating curve analysis. Results: PD-1+ tumor-infiltrating lymphocytes were numerous in extranodal marginal zone lymphomas and FL. Their amount decreased from FL grade 1 to grade 3 and to FL with transformation to diffuse large B-cell lymphoma. An increased amount of PD-1 tumor-infiltrating lymphocytes above the prognostic cut-off score (> 2.8%) was a positive prognostic factor of disease-specific survival (DSS) in FL-patients. Five percent of the studied 66 CLL/SLL cases showed unequivocal PD-1 positivity of neoplastic cells. Conclusions: Increased number of PD-1+ tumor-infiltrating lymphocytes is associated with significantly improved DSS in FL and may be useful to predict its heterogeneous clinical behavior. PD-1 has probably limited diagnostic value for primary histopathological CLL/SLL diagnostics.

The immune system and cancer evasion strategies: therapeutic concepts

The complicated interplay between cancer and the host immune system has been studied for decades. New insights into the human immune system as well as the mechanisms by which tumours evade immune control have led to the new and innovative therapeutic strategies that are considered amongst the medical breakthroughs of the last few years. Here, we will review the current understanding of cancer immunology in general, including immune surveillance and immunoediting, with a detailed look at immune cells (T cells, B cells, natural killer cells, macrophages and dendritic cells), immune checkpoints and regulators, sialic acid‐binding immunoglobulin‐like lectins (Siglecs) and other mechanisms. We will also present examples of new immune therapies able to reverse immune evasion strategies of tumour cells. Finally, we will focus on therapies that are already used in daily oncological practice such as the blockade of immune checkpoints cytotoxic T‐lymphocyte antigen 4 (CTLA‐4) and programmed death‐1 (PD‐1) in patients with metastatic melanoma or advanced lung cancer, or therapies currently being tested in clinical trials such as adoptive T‐cell transfer.

The PD-1/PD-L1 pathway: biological background and clinical relevance of an emerging treatment target in immunotherapy

Introduction: The co-inhibitory receptor programmed death 1 (PD-1) and its ligands are key regulators in a wide spectrum of immune responses and play a critical role in autoimmunity and self-tolerance as well as in cancer immunology. Emerging evidence suggests that cancer cells might use the PD-1/PD-ligand (PD-L) pathway to escape anti-tumor immunity. Based on this evidence, early phase human clinical trials targeting the PD-1/PD-L pathway are currently underway for multiple human cancers. Areas covered: The role of the PD-1/PD-L pathway in autoimmune disease, viral infections as well as in malignant neoplasms is discussed and an overview of the existing therapeutics as well as the results of clinical trials targeting this pathway in cancer is given. Expert opinion: The PD-1/PD-L pathway represents an important mechanism of immune evasion for malignant neoplasms. Early clinical trials indicate effectiveness of PD-1/PD-L pathway blockade in several solid cancers. However, greater insight into the exact mechanisms by which tumors are able to evade anti-tumor immunity is needed to increase clinical effectiveness, for example by combination blockade of diverse co-inhibitory receptors.

FOXP1 protein overexpression is associated with inferior outcome in nodal diffuse large B-cell lymphomas with non-germinal centre phenotype, independent of gains and structural aberrations at 3p14.1

Hoeller S, Schneider A, Haralambieva E, Dirnhofer S & Tzankov A
(2010) Histopathology 57, 73–80
FOXP1 protein overexpression is associated with inferior outcome in nodal diffuse large B‐cell lymphomas with non‐germinal centre phenotype, independent of gains and structural aberrations at 3p14.1

BOB.1, CD79a and cyclin E are the most appropriate markers to discriminate classical Hodgkin's lymphoma from primary mediastinal large B-cell lymphoma.

Hoeller S, Zihler D, Zlobec I, Obermann EC, Pileri SA, Dirnhofer S & Tzankov A
(2010) Histopathology56, 217–228

PCM1–JAK2-fusion: a potential treatment target in myelodysplastic–myeloproliferative and other hemato-lymphoid neoplasms

Importance of the field: Activating mutations of the JAK2 gene are of tumorigenic significance in myeloproliferative neoplasms. Translocations involving the JAK2 locus are of oncogenic importance in acute leukemias, myelodysplastic/myeloproliferative diseases and T-cell lymphomas. JAK2 locus gains, which are recurrent in Hodgkins- and primary mediastinal B-cell lymphoma, are also efficient mechanisms of JAK2 activation. Recently, specific drugs blocking JAK2 have been developed and are currently in clinical trials. Areas covered in this review: We discuss possible mechanisms of deregulation and the significance of pericentriolar material 1 (PCM)1–JAK2 fusion/t(8;9)(p21-23;p23-24) in hematolymphoid neoplasms. Such cases show morphological (myeloproliferaton, eosinophilia, myelofibrosis) and clinical (striking male predominance, aggressive course) similarities. Since increased JAK2 oligomerization and tyrosine kinase domain activation is the probable oncogenic mechanism in this instance, such patients are promising candidates for JAK2 inhibitor therapy. What the reader will gain: The reader will gain important insights considering PCM1–JAK2 fusion in hematologic malignancies. Take home message: JAK2 is a tyrosine kinase with oncogenic potential in hematologic malignancies. It can be activated by point mutations, translocations and amplifications. Beyond malignancies associated with JAK2 point mutations, those associated with translocations might be suitable for tyrosine kinase inhibitors, which merits prospective evaluation.

Molecular characteristics of mantle cell lymphoma presenting with clonal plasma cell component

The normal counterparts of mantle cell lymphoma (MCL) are naive, quiescent B cells that have not been processed through the germinal center (GC). For this reason, although lymphomas arising from GC or post-GC B cells often exhibit plasmacytic differentiation, MCL rarely presents with plasmacytic features. Seven cases of MCL with a monotypic plasma cell (PC) population were collected from 6 centers and were studied by immunohistochemistry, fluorescence immunophenotyping and interphase cytogenetics as a tool for the investigation of neoplasms analysis, capillary gel electrophoresis, and restriction fragment length polymorphism of immunoglobulin heavy chain analysis of microdissections of each of the MCL and PC populations to assess their clonal relationship. The clinical presentation was rather unusual compared with typical MCL, with 2 cases arising from the extranodal soft tissues of the head. All MCL cases were morphologically and immunohistochemically typical, bearing the t(11;14)(q13;q32). In all cases, the PC population was clonal. In 5 of the 7 cases, the MCL and PC clones showed identical restriction fragments, indicating a common clonal origin of the neoplastic population. The 2 cases with clonal diversity denoted the coexistence of 2 different tumors in a composite lymphoma/PC neoplasm. Our findings suggest that MCL can present with a PC component that is often clonally related to the lymphoma, representing a rare but unique biological variant of this tumor.