Comparison of immunophenotypes of small B-cell neoplasms in primary lymph node and concurrent blood or marrow samples

Preclinical anti-tumour activity of HexaBody-CD38, a next-generation CD38 antibody with superior complement-dependent cytotoxic activity

BACKGROUND

HexaBody®-CD38 (GEN3014) is a hexamerization-enhanced human IgG1 that binds CD38 with high affinity. The E430G mutation in its Fc domain facilitates the natural process of antibody hexamer formation upon binding to the cell surface, resulting in increased binding of C1q and potentiated complement-dependent cytotoxicity (CDC).

METHODS

Co-crystallization studies were performed to identify the binding interface of HexaBody-CD38 and CD38. HexaBody-CD38-induced CDC, antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), trogocytosis, and apoptosis were assessed using flow cytometry assays using tumour cell lines, and MM patient samples (CDC). CD38 enzymatic activity was measured using fluorescence spectroscopy. Anti-tumour activity of HexaBody-CD38 was assessed in patient-derived xenograft mouse models in vivo.

FINDINGS

HexaBody-CD38 binds a unique epitope on CD38 and induced potent CDC in multiple myeloma (MM), acute myeloid leukaemia (AML), and B-cell non-Hodgkin lymphoma (B-NHL) cells. Anti-tumour activity was confirmed in patient-derived xenograft models in vivo. Sensitivity to HexaBody-CD38 correlated with CD38 expression level and was inversely correlated with expression of complement regulatory proteins. Compared to daratumumab, HexaBody-CD38 showed enhanced CDC in cell lines with lower levels of CD38 expression, without increasing lysis of healthy leukocytes. More effective CDC was also confirmed in primary MM cells. Furthermore, HexaBody-CD38 efficiently induced ADCC, ADCP, trogocytosis, and apoptosis after Fc-crosslinking. Moreover, HexaBody-CD38 strongly inhibited CD38 cyclase activity, which is hypothesized to relieve immune suppression in the tumour microenvironment.

INTERPRETATION

Based on these preclinical studies, a clinical trial was initiated to assess the clinical safety of HexaBody-CD38 in patients with MM.

FUNDING

Genmab.

Anti CD38 monoclonal antibodies for multiple myeloma treatment

CD38 is a transmembrane glycoprotein with ectoenzymatic activity and is highly and uniformly expressed on multiple myeloma (MM) cells. CD38 is expressed also at relatively low levels on normal lymphoid and myeloid cells, and in some tissues of non-hematopoietic origin. The specificity of this target has increased interest in new drugs and triggered the development of the CD38 monoclonal antibodies Daratumumab (fully human) and Isatuximab (chimeric). CD38 antibodies have pleiotropic mechanisms of action including Fc-dependent immune effector mechanisms, direct apoptotic activity, and immunomodulatory effects by the elimination of CD38+ immune-suppressor cells. Monoclonal antibody-based therapy has revolutionized MM therapy in the latest years increasing depth of response. This product review will focus on anti-CD38 monoclonal antibodies Daratumumab and Isatuximab efficacy, safety, pharmacokinetic and pharmacodynamic data from clinical trials.

CD23 expression in follicular lymphoma: clinicopathologic correlations

Follicular lymphoma (FL) is typically a CD10+/CD5-/FMC-7+ B-cell lymphoma with variable CD23 expression. The clinical significance of CD23 expression in FL is uncertain. We studied the expression of CD23 by flow cytometry in 69 lymph nodes (LNs) and correlated it with pathologic and clinical parameters. Of 69 FLs, 48 (70%) were CD23+. Grade 3 FLs were CD23- more often (12/16 [75%]) than grade 1 and 2 cases (9/53 [17%]; P < .001). CD23 expression was more common in FLs in inguinal LNs than in other sites: 20 of 23 (87%) vs 28 of 46 (61%; P = .029). Overall survival (P = .002) and event-free survival (P < .0001) were longer in the CD23+ group than in the CD23- FLs. Our study shows that grade 3 FLs are more often CD23- than lower grade FLs and that FLs in inguinal LNs are more frequently CD23+ than in LNs from other sites. Furthermore, our findings also indicate that survival is significantly better in CD23+ FLs.

Predictive value of blood and bone marrow flow cytometry in B-cell lymphoma classification: comparative analysis of flow cytometry and tissue biopsy in 252 patients

OBJECTIVE

To study the effectiveness of peripheral blood (PB) and bone marrow flow cytometric immunophenotyping (FCIP) in predicting the histologic B-cell lymphoma type.

PATIENTS AND METHODS

We studied the FCIP results and tissue histopathology from 252 patients with B-cell lymphoma seen at Mayo Clinic's site in Rochester, MN, between January 1, 1997, and January 1, 2004, who had positive results on PB, bone marrow, or body fluid FCIP and a corresponding diagnostic tissue biopsy specimen.

RESULTS

Most of the B-cell lymphomas studied were low grade, with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma being most common. Flow cytometric immunophenotyping histogram analysis was more informative than tabulated percentage antigen positivity; surface immunoglobulin and CD20 staining intensity, CD5 and CD23 positivity, CD10 positivity, and the coexpression of CD11c/CD22 and CD103 were the most pertinent markers. Using these FCIP parameters and strict immunophenotypic definitions for CLL, mantle cell lymphoma (MCL), and hairy cell leukemia, we obtained greater than 95% specificity for each diagnosis. However, we encountered the following exceptions to standard paradigms of B-cell lymphoma-associated FCIP: (1) CD5 expression by disorders distinct from CLL and MCL, (2) lack of uniform CD5 positivity in some CLL and MCL cases, (3) absence of CD10 in approximately 50% of follicular lymphomas, and (4) expression of CD103 by occasional marginal zone lymphomas.

CONCLUSION

Stringent interpretation of PB and bone marrow FCIP results enables identification of certain B-cell lymphoma types. However, the observed exceptions to accepted immunophenotypic paradigms highlight the occasional phenotypic overlap among diseases and emphasize that a systematic approach to FCIP interpretations is key to providing clinically useful diagnostic information.

Application of Immunohistochemistry in the Diagnosis of Non-Hodgkin and Hodgkin Lymphoma

Context.—Beginning with the immunologic classifications of Lukes and Collins and Kiel and culminating in the Revised European-American Lymphoma and World Health Organization classifications, the diagnosis of lymphoid tumors relies heavily on the determination of cell lineage, maturation, and function, based on antigen expression in addition to morphology and clinical features. Technologic advances in immunology, antibody production, genetic analysis, cloning, and the identification of new genes and proteins by microarray and proteomics have provided pathologists with many antibodies to use in routine diagnosis.

Objective.—To provide guidance to the practicing pathologist in the appropriate selection of an antibody panel for the diagnosis of lymphoma based on morphology and relevant clinical data and to avoid pitfalls in the interpretation of immunohistochemical data. Attention is given to some of the newer antibodies, particularly against transcription factors, that are diagnostically and prognostically useful.

Data Sources.—The information presented in this article is based on review of the literature using the OVID database (Ovid MEDLINE 1950 to present with daily update) and 20 years of experience in diagnostic hematopathology.

Conclusions.—Immunophenotyping is required for the diagnosis and classification of lymphoid malignancies. Many paraffin-reactive antibodies are available to the pathologist but most are not specific. To avoid diagnostic pitfalls, interpretation of marker studies must be based on a panel and knowledge of a particular antigen's expression in normal, reactive, and neoplastic conditions.

Role of CD21 antigen in diffuse large B-cell lymphoma and its clinical significance

Recent advances in immunological and molecular technology have prompted proposals to change tumour classification and treatment strategies. Cell surface antigens are now easy to access, and tumour origins and clinical characteristics are now readily identifiable. However, in diffuse large B-cell lymphoma (DLBCL), one of the heterogeneous forms of haematological malignancy, the clinical significance of tumour surface antigens has not been well documented. We analysed the tumour surface antigens of 50 tumours from newly diagnosed DLBCL patients by flow cytometry in accordance with their clinical characteristics and followed the patients for a median 3.7 years. Statistical analysis showed that CD21 expression was significantly negatively associated with mortality in DLBCL (CD21 negative versus positive; relative risk = 2.36, P < 0.05). As a result of these clinical observations, we generated CD21-overexpressed (CD21(+)) lymphoma cell lines after gene transfection and analysed tumour cell growth in vivo in immunocompromised mice. Mice challenged with vector-only transfectants and parental cells as controls died within 50 d. In contrast, mice injected with CD21(+) transfectants exhibited significantly reduced tumour growth and 83% survived long term (versus control groups; P < 0.05). Interestingly, all established CD21(+) transfectants (six clones from different bulks) showed homotypic aggregation during in vitro cell culture, and anti-CD21 antibodies did not block this aggregation. Expression of CD21 is strongly associated with increased survival in DLBCL in vivo. CD21 expression may be indirectly concerned with the expression of additional cell adhesion molecules.

Histopathology of B-cell chronic lymphocytic leukemia

Histologic and immunohistologic findings of B-cell chronic lymphocytic leukemia/small lymphocytic leukemia are revised in the light of the more recent knowledge on the pathobiology of the disease. The guidelines for the optimal handling of the bioptic samples are provided. The relevance of the examination of trephines and surgical specimens is outlined with special reference to the identification of risk factors in individual patients.

Hodgkin and non-Hodgkin lymphoma involving bone marrow

The role of bone marrow examination in diagnosis and staging of patients with Hodgkin lymphoma, B-non-Hodgkin lymphoma, and T-non-Hodgkin lymphoma is reviewed. Optimal routine and specialized bone marrow examination techniques are discussed. The salient morphologic, immunophenotypic, and genetic features of mature and immature B, T neoplasms and classic Hodgkin lymphoma in bone marrow are delineated, along with recommendations to distinguish these overt neoplasms from non-neoplastic processes.