Abstract | PURPOSE: L612, a human IgM monoclonal antibody produced by an EBV-transformed human B-cell line, binds to ganglioside GM3 and kills GM3-positive human melanoma cells in the presence of complement. It has been shown to be effective in some patients with late-stage melanoma. L612 consists of hexameric IgM (about 20%), pentameric IgM (about 74%), and other minor IgM molecules. Because hexameric IgM activates complement more effectively than pentameric IgM, we developed and evaluated a hexamer-dominant recombinant IgM for clinical applications. EXPERIMENTAL DESIGN: Chinese hamster ovary (CHO) cells were transfected with heavy- and light-chain genes of L612, with or without the joining-chain gene. Antitumor effects of the recombinant IgM secreted from CHO cells were evaluated in vitro and in vivo. RESULTS: Recombinant IgM secreted from CHO cells without the joining chain (designated CA19) was approximately 80% hexameric, whereas recombinant IgM from CHO cells transfected with heavy-, light-, and joining-chain genes (designated CJ45) was about 90% pentameric. Both CA19 and CJ45 recombinant IgMs caused complement-dependent cytotoxicity against human and mouse melanoma cell lines, but the amount of CA19 required for 50% specific cytotoxicity was 5 to 10 times smaller. I.v. injection of CA19 compared with CJ45 or native L612 elicited more profound antitumor activity in nude rats bearing a GM3-positive mouse melanoma xenograft. CONCLUSIONS: A hexamer-dominant human IgM against GM3 may provide a more potent treatment option for patients with GM3-positive melanoma.
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Authors | Yumiko Azuma, Yuji Ishikawa, Shigeto Kawai, Toshiaki Tsunenari, Hiroyuki Tsunoda, Tomoyuki Igawa, Shin-ichiro Iida, Masahiko Nanami, Masami Suzuki, Reiko F Irie, Masayuki Tsuchiya, Hisafumi Yamada-Okabe |
Journal | Clinical cancer research : an official journal of the American Association for Cancer Research
(Clin Cancer Res)
Vol. 13
Issue 9
Pg. 2745-50
(May 01 2007)
ISSN: 1078-0432 [Print] United States |
PMID | 17473208
(Publication Type: Journal Article)
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Chemical References |
- Antibodies, Monoclonal
- Antibodies, Monoclonal, Humanized
- G(M3) Ganglioside
- L612 monoclonal antibody
- Recombinant Proteins
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Topics |
- Animals
- Antibodies, Monoclonal
(therapeutic use)
- Antibodies, Monoclonal, Humanized
- CHO Cells
- Cell Line, Tumor
- Cricetinae
- Cricetulus
- G(M3) Ganglioside
(immunology)
- Humans
- Melanoma
(chemistry, drug therapy, pathology)
- Recombinant Proteins
(therapeutic use)
- Skin Neoplasms
(chemistry, drug therapy, pathology)
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