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Epratuzumab, a humanized monoclonal antibody targeting CD22: characterization of in vitro properties.
Clin Cancer Res. 2003 Sep 01; 9(10 Pt 2):3982S-90S.CC

Abstract

PURPOSE

Epratuzumab is a novel humanized antihuman CD22 IgG1 antibody that has recently shown promising clinical activity, both as a single agent and in combination with rituximab, in patients with non-Hodgkin's lymphomas (NHL). In an attempt to better understand the mode of action of epratuzumab, the antibody was tested in vitro in a variety of cell-based assays similar to those used to evaluate the biological activity of other therapeutic monoclonal antibodies, including rituximab. In this report, we present epratuzumab activities as they relate to binding, signaling, and internalization of the receptor CD22.

METHODS

Chinese hamster ovary-expressed CD22 extracellular domain was used to measure epratuzumab affinity on Biacore. CD22 receptor density and internalization rate were measured indirectly using a monovalently labeled, noncompeting (with epratuzumab) anti-CD22 antibody on Burkitt lymphoma cell lines, primary B cells derived from fresh tonsils, and B cells separated from peripheral blood samples obtained from patients with chronic lymphocytic leukemia or healthy volunteers. Epratuzumab-induced CD22 phosphorylation was measured by immunoprecipitation/Western blot and compared with that induced by anti-IgM stimulation.

RESULTS

Epratuzumab binds to CD22-extracellular domain, with an affinity of K(D) = 0.7 nM. Binding of epratuzumab to B cell lines, or primary B cells from healthy individuals and patients with NHL, results in rapid internalization of the CD22/antibody complex. Internalization appears to be faster at early time points in cell lines than in primary B cells and NHL patient-derived B cells, but the maximum internalization reached is comparable for all B cell populations after several hours of treatment and appears to reach saturation at antibody concentrations of 1-5 micro g/ml. Finally, epratuzumab binding results in modest but significant CD22 phosphorylation.

CONCLUSIONS

Epratuzumab represents an excellent anti-CD22 ligating agent, highly efficacious in inducing CD22 internalization, and can induce phosphorylation. Although we cannot unequivocally demonstrate here that epratuzumab-induced internalization and signaling of CD22 directly contribute to its therapeutic efficacy, these properties are the fundamental characteristics of the target CD22 and its interaction with epratuzumab. Similar results were observed when epratuzumab was tested in vitro on Burkitt B cell lines as well as on primary normal B cells and neoplastic B cells separated from fresh peripheral blood samples from patients with chronic lymphocytic leukemia.

Authors+Show Affiliations

Amgen, Inc., Thousand Oaks, California 91320, USA. jcarnaha@amgen.comNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

14506197

Citation

Carnahan, Josette, et al. "Epratuzumab, a Humanized Monoclonal Antibody Targeting CD22: Characterization of in Vitro Properties." Clinical Cancer Research : an Official Journal of the American Association for Cancer Research, vol. 9, no. 10 Pt 2, 2003, 3982S-90S.
Carnahan J, Wang P, Kendall R, et al. Epratuzumab, a humanized monoclonal antibody targeting CD22: characterization of in vitro properties. Clin Cancer Res. 2003;9(10 Pt 2):3982S-90S.
Carnahan, J., Wang, P., Kendall, R., Chen, C., Hu, S., Boone, T., Juan, T., Talvenheimo, J., Montestruque, S., Sun, J., Elliott, G., Thomas, J., Ferbas, J., Kern, B., Briddell, R., Leonard, J. P., & Cesano, A. (2003). Epratuzumab, a humanized monoclonal antibody targeting CD22: characterization of in vitro properties. Clinical Cancer Research : an Official Journal of the American Association for Cancer Research, 9(10 Pt 2), 3982S-90S.
Carnahan J, et al. Epratuzumab, a Humanized Monoclonal Antibody Targeting CD22: Characterization of in Vitro Properties. Clin Cancer Res. 2003 Sep 1;9(10 Pt 2):3982S-90S. PubMed PMID: 14506197.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Epratuzumab, a humanized monoclonal antibody targeting CD22: characterization of in vitro properties. AU - Carnahan,Josette, AU - Wang,Paul, AU - Kendall,Richard, AU - Chen,Ching, AU - Hu,Sylvia, AU - Boone,Tom, AU - Juan,Todd, AU - Talvenheimo,Jane, AU - Montestruque,Silvia, AU - Sun,Jilin, AU - Elliott,Gary, AU - Thomas,John, AU - Ferbas,John, AU - Kern,Brent, AU - Briddell,Robert, AU - Leonard,John P, AU - Cesano,Alessandra, PY - 2003/9/25/pubmed PY - 2004/6/2/medline PY - 2003/9/25/entrez SP - 3982S EP - 90S JF - Clinical cancer research : an official journal of the American Association for Cancer Research JO - Clin Cancer Res VL - 9 IS - 10 Pt 2 N2 - PURPOSE: Epratuzumab is a novel humanized antihuman CD22 IgG1 antibody that has recently shown promising clinical activity, both as a single agent and in combination with rituximab, in patients with non-Hodgkin's lymphomas (NHL). In an attempt to better understand the mode of action of epratuzumab, the antibody was tested in vitro in a variety of cell-based assays similar to those used to evaluate the biological activity of other therapeutic monoclonal antibodies, including rituximab. In this report, we present epratuzumab activities as they relate to binding, signaling, and internalization of the receptor CD22. METHODS: Chinese hamster ovary-expressed CD22 extracellular domain was used to measure epratuzumab affinity on Biacore. CD22 receptor density and internalization rate were measured indirectly using a monovalently labeled, noncompeting (with epratuzumab) anti-CD22 antibody on Burkitt lymphoma cell lines, primary B cells derived from fresh tonsils, and B cells separated from peripheral blood samples obtained from patients with chronic lymphocytic leukemia or healthy volunteers. Epratuzumab-induced CD22 phosphorylation was measured by immunoprecipitation/Western blot and compared with that induced by anti-IgM stimulation. RESULTS: Epratuzumab binds to CD22-extracellular domain, with an affinity of K(D) = 0.7 nM. Binding of epratuzumab to B cell lines, or primary B cells from healthy individuals and patients with NHL, results in rapid internalization of the CD22/antibody complex. Internalization appears to be faster at early time points in cell lines than in primary B cells and NHL patient-derived B cells, but the maximum internalization reached is comparable for all B cell populations after several hours of treatment and appears to reach saturation at antibody concentrations of 1-5 micro g/ml. Finally, epratuzumab binding results in modest but significant CD22 phosphorylation. CONCLUSIONS: Epratuzumab represents an excellent anti-CD22 ligating agent, highly efficacious in inducing CD22 internalization, and can induce phosphorylation. Although we cannot unequivocally demonstrate here that epratuzumab-induced internalization and signaling of CD22 directly contribute to its therapeutic efficacy, these properties are the fundamental characteristics of the target CD22 and its interaction with epratuzumab. Similar results were observed when epratuzumab was tested in vitro on Burkitt B cell lines as well as on primary normal B cells and neoplastic B cells separated from fresh peripheral blood samples from patients with chronic lymphocytic leukemia. SN - 1078-0432 UR - https://www.unboundmedicine.com/medline/citation/14506197/Epratuzumab_a_humanized_monoclonal_antibody_targeting_CD22:_characterization_of_in_vitro_properties_ L2 - http://clincancerres.aacrjournals.org/cgi/pmidlookup?view=long&pmid=14506197 DB - PRIME DP - Unbound Medicine ER -