Correlation between histology and immunophenotype in a series of 322 cases of non-Hodgkin's lymphoma

Otlertuzumab (TRU-016), an anti-CD37 monospecific ADAPTIR(™) therapeutic protein, for relapsed or refractory NHL patients

CD37 is cell surface tetraspanin present on normal and malignant B cells. Otlertuzumab (TRU-016) is a novel humanized anti-CD37 protein therapeutic. Patients with relapsed or refractory follicular non-Hodgkin lymphoma (FL), mantle cell lymphoma (MCL), or Waldenström's macroglobulinaemia (WM) received otlertuzumab at 20 mg/kg administered intravenously once a week for up to 8 weeks followed by 4 monthly doses. Sixteen patients were treated; median age was 62·5 years (range, 41-81), and median number of prior regimens was 4 (range, 1-7). Twelve patients were refractory to prior treatment, 5 were refractory to rituximab. The mean terminal half-life was 9·5 days. Lymph node reduction of ≥50% by computerized tomography scan measurements was seen in 3 of 12 patients, including one FL patient who had a partial response. One WM patient had a minor response. The most frequent adverse events were neutropenia, fatigue, nausea, thrombocytopenia, diarrhoea, and peripheral oedema; most were grade 1/2. Otlertuzumab treatment appears to have been well tolerated by the patients in this study. Clinical activity was observed in this small heterogeneous cohort of highly refractory, heavily pretreated B-cell non-Hodgkin lymphoma patients. These data suggest that further clinical investigation in non-Hodgkin lymphoma is warranted.

A novel Fc-engineered monoclonal antibody to CD37 with enhanced ADCC and high proapoptotic activity for treatment of B-cell malignancies

The tetraspanin CD37 is widely expressed in B-cell malignancies and represents an attractive target for immunotherapy with mAbs. We have chimerized a high-affinity mouse Ab to CD37 and engineered the CH2 domain for improved binding to human Fcγ receptors. The resulting mAb 37.1 showed high intrinsic proapoptotic activity on malignant B cells accompanied by homotypic aggregation. Furthermore, the Ab-mediated high Ab-dependent cell-mediated cytotoxicity (ADCC) on lymphoma and primary CLL cells. mAb 37.1 strongly depleted normal B cells as well as spiked B-lymphoma cells in blood samples from healthy donors as well as malignant B cells in blood from CLL patients. In all assays, mAb 37.1 was superior to rituximab in terms of potency and maximal cell lysis. A single dose of mAb CD37.1 administered to human CD37-transgenic mice resulted in a reversible, dose-dependent reduction of peripheral B cells. In a Ramos mouse model of human B-cell lymphoma, administration of mAb 37.1 strongly suppressed tumor growth. Finally, a surrogate Fc-engineered Ab to macaque CD37, with in vitro proapoptotic and ADCC activities very similar to those of mAb 37.1, induced dose-dependent, reversible B-cell depletion in cynomolgus monkeys. In conclusion, the remarkable preclinical pharmacodynamic and antitumor effects of mAb 37.1 warrant clinical development for B-cell malignancies.

CD5+ follicle center lymphoma. Immunophenotyping detects a unique subset of "floral" follicular lymphoma

The "floral" variant of follicle center lymphoma (FCL) may be confused with progressive transformation of germinal centers or lymphocyte predominance Hodgkin lymphoma. Immunohistochemistry and gene rearrangement studies are usually sufficient to differentiate among these entities. We present 11 cases of floral FCL that were evaluated at our institution by flow cytometry, immunohistochemistry, or both and by polymerase chain reaction-based molecular analysis. In 4 cases, the neoplastic B cells coexpressed CD5 antigens; 3 of these 4 cases also were CD10+, and all demonstrated rearrangement within the bcl-2 locus. These findings demonstrate that a subset of floral FCL is CD5+. Recognition of this immunophenotype is important to avoid misdiagnosis of nodular variants of small lymphocytic lymphoma and mantle cell lymphoma. Studies suggest that expression of CD5 by neoplastic germinal center cells might result from alterations of the follicular microenvironment and/or inappropriate B-cell responses to cytokine networks.

Primary non-Hodgkin's lymphoma of the jaws: immunohistochemical and genetic review of 10 cases

PURPOSE

Non-Hodgkin's lymphoma (NHL) comprises a group of malignant lymphoproliferative diseases characterized by clonal expansion of lymphocytes at various levels of ontogenetic development. The aim of this study was to review the immunohistochemical and cytogenetic features of 10 cases of NLH of the jaws to determine their respective derivation.

PATIENTS AND METHODS

Histopathologic and immunohistochemical review of 10 cases of large-cell lymphomas of the jaws, together with Southern blot analysis of 2 of the cases, was performed and results compared with the findings in the literature.

RESULTS

In the 10 cases studied, the average age of onset of the NHL was 51 years, with a male-to-female ratio of 3:2. Tumefaction was the first clinical sign of disease. Eight of 10 cases were high-grade, large-cell NHLs, centroblastic type. Two cases were high-grade, large-cell NHL, immunoblastic type.

CONCLUSION

The immunohistochemical and Southern blot data remain the principal laboratory aids in the diagnosis and characterization of NHL, and they provide critical information for guiding clinicians to the appropriate treatment protocol for these malignancies.

Cutaneous histiocytic malignancy. Immunohistochemical re-examination of cases previously diagnosed as cutaneous "histiocytic lymphoma" and "malignant histiocytosis"

True histiocytic lymphoma (THL) and malignant histiocytosis (MH) have been defined by clinical and histologic findings and enzyme histochemistry. We reviewed cases previously diagnosed as cutaneous histiocytic lymphoma (HL) and MH with cutaneous lesions. These cases had been classified as "histiocytic" on the basis of previous enzyme histochemistry profiles of frozen tissue. Cutaneous tumor cells were reevaluated using a panel of immunohistochemical stains in formalin-fixed, paraffin-embedded tissue in correlation with histopathologic examination. The antibodies used in this study were directed against CD45 (leukocyte common antigen [LCA]), CD20 (L26) for B cells, CD3 and CD45RO (UCHL-1) for T cells, CD68 (KP-1) and lysozyme for histiocytes, as well as CD30 (BerH2) for Ki-1 positive cells. On re-evaluation, the seven cases originally classified as HL were reclassified as one case of THL with neoplastic cells positive for CD68 (KP-1) and lysozyme, two cases with immunohistochemical features of Ki-l lymphoma (including one of T-cell lineage), three cases of T-cell lymphoma, and one case of B-cell lymphoma, all associated with variable degrees of reactive histiocytosis. The four cases originally classified as MH were reclassified as two cases of MH and two cases of uncertain lineage. Although rare, histiocytic malignancies do exist. However, the diagnosis of histiocytic malignancy should be made only after careful correlation of atypical tumor cells in histopathologic sections and sections stained immunohistochemically. Erroneous classification of reactive histiocytes as neoplastic histiocytes using only enzyme histochemistry in frozen sections is a pitfall to be avoided.

Immunophenotyping of low-grade B-cell lymphoma in blood and bone marrow: poor correlation between immunophenotype and cytological/histological classification

Results of immunophenotypic examinations of peripheral blood and/or bone marrow (BM), involved in low-grade B-cell non-Hodgkin's lymphomas, were compared with the results of cytomorphological and histopathological examinations in 133 adult patients. 69 cases of chronic B-lymphocytic leukaemia (B-CLL), 16 centrocytic (CC) lymphomas, 14 centroblastic-centrocytic (CB/CC) lymphomas, 15 immunocytomas (IC), 10 cases of hairy cell leukaemia (HCL), four prolymphocytic leukaemias (PLL), two B-CLL in transformation, one splenic lymphoma with villous lymphocytes (SLVL), one hairy cell leukaemia variant (HCL-V), and one lymphocytic lymphoma (LC) were classified according to the Kiel and/or FAB classification. Leukaemic disease was found in 105 cases. The following markers were used for immunocytology (APAAP technique) of blood and/or BM smears: CD19, CD5, CD10, CD11c, CD14, CD21, CD22, CD23, CD25, CD38 and TdT. All cases tested showed CD19, but no TdT expression. Every case of HCL had a distinct phenotype with expression of CD11c, CD22 and CD25 and the lack of CD5 and CD23 antigens. In all other NHL cases a very heterogenous expression of CD-antigens with no significant correlations to the cytomorphological subtypes was found. The expression of CD5 is a frequent but inconstant finding in lymphoproliferative diseases other than B-CLL, so 50% of CB/CC, 75% of CC and 80% of IC were CD5 positive. Our results indicate that, with the exception of HCL, the diagnostic relevance of immunophenotyping for the classification of cytomorphologically and histopathologically defined subtypes in blood and/or BM is of very limited value.

Clonality of T cell and phenotypically undefined lymphoid neoplasms: the value of genotypic analyses

The value of genotypic analysis for routine assessment of leukaemia and lymphoma was shown by the findings in a selected series of 30 cases. T cell receptor (TcR) gene rearrangements were observed in six out of nine cases of CD3+ CD8+ lymphocytoses and provided clear evidence for clonality in this group. The T cell proliferations in two of the remaining cases masked B cell lymphocytic leukaemia and hairy cell leukaemia, while in the third case no cause was found for the polyclonal proliferation. Heterogeneity of phenotype and genotype were observed in peripheral T cell lymphomas: one out of six cases showed TcR gene rearrangement, one case retained its germline configuration, a further case masked B cell lymphoma and the remainder were polyclonal. Genotypic analysis was helpful in the analysis of a tumour of mixed T cell and myeloid phenotype which was shown to be germline for TcR and immunoglobulin genes, consistent with a myeloid origin. Two histiocytic tumours were found to have clonal rearrangement of TcR genes. Nine out of 11 B cell tumours showed immunoglobulin gene rearrangement. It is concluded that genetic analyses are useful in the analysis of T cell, histiocytic, and B cell tumours in which an immunoglobulin phenotype cannot be defined.