Analysis of CD16+CD56dim NK cells from CLL patients: evidence supporting a therapeutic strategy with optimized anti-CD20 monoclonal antibodies

Abstract

Although anti-CD20 monoclonal antibodies (mAbs) show promise for the treatment of chronic lymphocytic leukemia (CLL), the success of the anti-CD20 mAb rituximab in CLL treatment has been limited. Novel anti-CD20 mAbs with more potent cytotoxic activity have recently been engineered, but so far most have only been tested in vitro with natural killer (NK) cells from healthy donors. Because it is still unclear whether these optimized cytotoxic mAbs will improve NK-cell killing of tumor cells in CLL patients, we characterized the relevant phenotypic and functional features of NK cells from CLL patients in detail. Expression of inhibitory and activating NK-cell receptors and of Fc gamma receptor IIIA (FccRIIIA) is well preserved in CD16 þ CD56 dim cytotoxic NK cells from these patients, independently of disease progression. These cells are fully functional following cytokine stimulation. In addition, the FccRIIIA-optimized LFB-R603 anti-CD20 mAb mediates 100 times greater antibody-dependent cell-mediated cytotoxicity by NK cells from CLL patients and healthy donors than rituximab. Enhanced degranulation against autologous B-CLL cells is observed at lower concentrations of LFB-R603 than rituximab, regardless of CLL prognostic factors. These findings strongly justify further clinical development of anti-CD20 mAbs optimized for FccR engagement in CLL patients.

Combined glyco- and protein-Fc engineering simultaneously enhance cytotoxicity and half-life of a therapeutic antibody

“…The C6A-78A variant, the 6 chosen variants (Table 2), the IgG-WT and the positive control IgG-YTE were produced as full-length IgGs with the variable regions of the chimeric anti-human CD20 CAT 13.6E12. 36 To combine the advantages of glyco-and protein-Fc engineering, the IgG variants were produced in YB2/0 cells (EMABling ® platform), permitting low fucosylation of the glycan moiety present in the mAb and thus enhanced ADCC as previously described for the anti-CD20 mAb ublituximab [37][38][39] and the anti-RhD mAb roledumab. 40,41 Before any subsequent biological test, the quality of the purified IgGs was assessed using several biochemical techniques ensuring that the biophysical behavior of the IgGs were not modified due to the mutations introduced (i.e., similar pI and molecular weights, aggregation rates < 5% and endotoxin levels < 7UI/mg).…”

Glycovariant anti-CD37 monospecific protein therapeutic exhibits enhanced effector cell-mediated cytotoxicity against chronic and acute B cell malignancies

“…28 This finding, however, has been challenged by others. 29 To test whether CLL NK cells would be capable of mediating an effective response with SMIP-016 GV , we used NK cells from patients with early stage disease as effectors in ADCC assays against Raji cells targets. Their response was compared with the response from NK cells isolated from healthy donors.…”

Mono- and dual-targeting triplebodies activate natural killer cells and have anti-tumor activityin vitroandin vivoagainst chronic lymphocytic leukemia

“…1,2 It is characterized by progressive outgrowth of monoclonal CD5 C /CD19 C double positive B cells in peripheral blood, bone marrow as well as lymph nodes and spleen. 3 Therapeutic monoclonal antibodies have positively contributed toward the management of CLL.…”

“…3 Therapeutic monoclonal antibodies have positively contributed toward the management of CLL. 2,4 A chimeric anti-CD20 antibody-rituximaband a humanized anti-CD52 antibody-alemtuzumab-have been recently introduced for the treatment of progressive diseases. 2,4 Initially, rituximab as a single agent did not improve overall response rate (ORR) in CLL; however, when combined with fludarabine, this chemo-immunotherapeutic regimen improved ORR and complete response rates (CR).…”

“…2,4 A chimeric anti-CD20 antibody-rituximaband a humanized anti-CD52 antibody-alemtuzumab-have been recently introduced for the treatment of progressive diseases. 2,4 Initially, rituximab as a single agent did not improve overall response rate (ORR) in CLL; however, when combined with fludarabine, this chemo-immunotherapeutic regimen improved ORR and complete response rates (CR). 2,4 Current chemo/immunotherapy and novel drugs including tyrosine kinase or Bcl-2 inhibitors result in durable remissions in a substantial proportion of patients.…”