Rebmab200, a humanized monoclonal antibody targeting the sodium phosphate transporter NaPi2b displays strong immune mediated cytotoxicity against cancer: a novel reagent for targeted antibody therapy of cancer.
NaPi2b, a sodium-dependent phosphate transporter, is highly expressed in ovarian carcinomas and is recognized by the murine monoclonal antibody MX35. The antibody had shown excellent targeting to ovarian cancer in several early phase clinical trials but being murine the antibody's full therapeutic potential could not be explored. To overcome this impediment we developed a humanized antibody version named Rebmab200, expressed in human PER.C6® cells and cloned by limiting dilution. In order to select a clone with high therapeutic potential clones were characterized using a series of physicochemical assays, flow cytometry, real-time surface plasmon resonance, glycosylation analyses, immunohistochemistry, antibody-dependent cell-mediated cytotoxicity, complement-dependent-cytotoxicity assays and quantitative PCR. Comparative analyses of Rebmab200 and MX35 monoclonal antibodies demonstrated that the two antibodies had similar specificity for NaPi2b by flow cytometry with a panel of 30 cell lines and maintained similar kinetic parameters. Robust and high producer cell clones potentially suitable for use in manufacturing were obtained. Rebmab200 antibodies were assessed by immunohistochemistry using a large panel of tissues including human carcinomas of ovarian, lung, kidney and breast origin. An assessment of its binding towards 33 normal human organs was performed as well. Rebmab200 showed selected strong reactivity with the tested tumor types but little or no reactivity with the normal tissues tested confirming its potential for targeted therapeutics strategies. The remarkable cytotoxicity shown by Rebmab200 in OVCAR-3 cells is a significant addition to the traits of stability and productivity displayed by the top clones of Rebmab200. Antibody-dependent cell-mediated toxicity functionality was confirmed in repeated assays using cancer cell lines derived from ovary, kidney and lung as targets. To explore use of this antibody in clinical trials, GMP production of Rebmab200 has been initiated. As the next step of development, Phase I clinical trials are now planned for translation of Rebmab200 into the clinic.
Lab. de Biofármacos em Células Animais, Instituto Butantan, São Paulo, Brazil.
Mariana
M
Lopes dos Santos
Fernanda Perez
FP
Yeda
Lilian Rumi
LR
Tsuruta
Bruno Brasil
BB
Horta
Alécio A
AA
Pimenta
Theri Leica
TL
Degaki
Ibere C
IC
Soares
Maria Carolina
MC
Tuma
Oswaldo Keith
OK
Okamoto
Venancio A F
VA
Alves
Lloyd J
LJ
Old
Gerd
G
Ritter
Ana Maria
AM
Moro
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D061067:Antibodies, Monoclonal, Humanized / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*; D000918:Antibody Specificity / Q000276:immunology; D000920:Antibody-Dependent Cell Cytotoxicity / Q000187:drug effects* / Q000276:immunology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000276:immunology; D003165:Complement System Proteins / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D007700:Kinetics; D051379:Mice; D009369:Neoplasms / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000276:immunology / Q000473:pathology; D011485:Protein Binding / Q000276:immunology; D050614:Sodium-Phosphate Cotransporter Proteins, Type IIb / Q000037:antagonists & inhibitors* / Q000276:immunology; D020349:Surface Plasmon Resonance
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; C493557:SLC34A2 protein, human; D050614:Sodium-Phosphate Cotransporter Proteins, Type IIb; D003165:Complement System Proteins