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HN125: A Novel Immunoadhesin Targeting MUC16 with Potential for Cancer Therapy.

Xiang X, Feng M, Felder M, Connor JP, Man YG, Patankar MS, Ho M - J Cancer (2011)

Bottom Line: Because of its lower immunogenicity in patients, a fully human protein is the most desirable format for clinical applications.We believe that the methods developed here may apply to the generation of other tumor-targeting immunoadhesins when it is difficult to obtain a human monoclonal antibody to a given antigen for clinical applications.The resultant immunoadhesins can have advantages usually found in monoclonal antibodies such as ease of purification, high binding affinity and effector functions.

View Article: PubMed Central - PubMed

Affiliation: 1. Antibody Therapy Unit, Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA;

ABSTRACT

Background: The mucin MUC16 expresses the repeating peptide epitope CA125 that has been known for decades to be a well-validated cancer marker that is overexpressed on the cell surface of ovarian cancers and other malignant tumors. In spite of recent efforts to make mouse monoclonal antibodies to MUC16 to treat ovarian cancer, a human monoclonal antibody against this mucin has not been described. MUC16 interacts with mesothelin, a protein that mediates heterotypic cancer cell adhesion, indicating that MUC16 and mesothelin play an important role in the peritoneal implantation and metastasis of ovarian tumors. Therefore, a suitable candidate for therapeutic targeting of MUC16 would functionally block the interaction of MUC16 and mesothelin.

Methodology/principal findings: Here we report the generation of a novel immunoadhesin, HN125, against MUC16 that consists of a functional MUC16 binding domain of mesothelin (IAB) and the Fc portion of a human antibody IgG1. The yield for purified HN125 proteins is over 100 µg/mL of HEK-293 culture supernatant. We show that HN125 has high and specific affinity for MUC16-expressing cancer cells by flow cytometry and immunohistochemistry. HN125 has the ability to disrupt the heterotypic cancer cell adhesion mediated by the MUC16-mesothelin interaction. Moreover, it elicits strong antibody-dependent cell mediated cytotoxicity against MUC16-positive cancer cells in vitro.

Conclusion/significance: This report describes a novel human immunotherapeutic agent highly specific for MUC16 with potential for treating ovarian cancer and other MUC16-expressing tumors. Because of its lower immunogenicity in patients, a fully human protein is the most desirable format for clinical applications. We believe that the methods developed here may apply to the generation of other tumor-targeting immunoadhesins when it is difficult to obtain a human monoclonal antibody to a given antigen for clinical applications. The resultant immunoadhesins can have advantages usually found in monoclonal antibodies such as ease of purification, high binding affinity and effector functions.

No MeSH data available.


Related in: MedlinePlus

Inhibition of the HN125 binding to MUC16 by OC125. OVCAR3 cells were probed with an anti-CA125 mAb OC125 (solid dark line) or an irrelevant isotype mAb control (light gray shading). Cells were incubated with 0 (A, C) or 10 μg/mL of full-length mesothelin (MSLN) (B) or HN125 (D) before OC125 was added. Their GeoMean values: A, 480; B, 262; C, 410; D 287. GeoMean of the isotype antibody control was about 5.0.
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Figure 4: Inhibition of the HN125 binding to MUC16 by OC125. OVCAR3 cells were probed with an anti-CA125 mAb OC125 (solid dark line) or an irrelevant isotype mAb control (light gray shading). Cells were incubated with 0 (A, C) or 10 μg/mL of full-length mesothelin (MSLN) (B) or HN125 (D) before OC125 was added. Their GeoMean values: A, 480; B, 262; C, 410; D 287. GeoMean of the isotype antibody control was about 5.0.

Mentions: The well-characterized OC125 mAb was used to investigate the mesothelin binding domain on MUC16 by flow cytometry. OC125 developed by Bast et al. reacts with CA125, an epitope of MUC16 present on the surface of most epithelial ovarian tumors 45. Figure 4 shows that when HN125 or full-length mesothelin was incubated with OVCAR3 cells first, the interaction between OC125 and MUC16 was reduced. The difference was slightly larger using full-length mesothelin than using HN125. No difference was found using another anti-CA125 mouse mAb M11 (data not shown). The marginal inhibition observed with OC125 indicated that the HN125 binding epitope may be different than the OC125 binding epitope (CA125). Previous studies indicated that the mesothelin-binding site on CA125 is N-glycan dependent 23. The precise binding site of mesothelin on MUC16 remains elusive.


HN125: A Novel Immunoadhesin Targeting MUC16 with Potential for Cancer Therapy.

Xiang X, Feng M, Felder M, Connor JP, Man YG, Patankar MS, Ho M - J Cancer (2011)

Inhibition of the HN125 binding to MUC16 by OC125. OVCAR3 cells were probed with an anti-CA125 mAb OC125 (solid dark line) or an irrelevant isotype mAb control (light gray shading). Cells were incubated with 0 (A, C) or 10 μg/mL of full-length mesothelin (MSLN) (B) or HN125 (D) before OC125 was added. Their GeoMean values: A, 480; B, 262; C, 410; D 287. GeoMean of the isotype antibody control was about 5.0.
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Related In: Results  -  Collection

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Figure 4: Inhibition of the HN125 binding to MUC16 by OC125. OVCAR3 cells were probed with an anti-CA125 mAb OC125 (solid dark line) or an irrelevant isotype mAb control (light gray shading). Cells were incubated with 0 (A, C) or 10 μg/mL of full-length mesothelin (MSLN) (B) or HN125 (D) before OC125 was added. Their GeoMean values: A, 480; B, 262; C, 410; D 287. GeoMean of the isotype antibody control was about 5.0.
Mentions: The well-characterized OC125 mAb was used to investigate the mesothelin binding domain on MUC16 by flow cytometry. OC125 developed by Bast et al. reacts with CA125, an epitope of MUC16 present on the surface of most epithelial ovarian tumors 45. Figure 4 shows that when HN125 or full-length mesothelin was incubated with OVCAR3 cells first, the interaction between OC125 and MUC16 was reduced. The difference was slightly larger using full-length mesothelin than using HN125. No difference was found using another anti-CA125 mouse mAb M11 (data not shown). The marginal inhibition observed with OC125 indicated that the HN125 binding epitope may be different than the OC125 binding epitope (CA125). Previous studies indicated that the mesothelin-binding site on CA125 is N-glycan dependent 23. The precise binding site of mesothelin on MUC16 remains elusive.

Bottom Line: Because of its lower immunogenicity in patients, a fully human protein is the most desirable format for clinical applications.We believe that the methods developed here may apply to the generation of other tumor-targeting immunoadhesins when it is difficult to obtain a human monoclonal antibody to a given antigen for clinical applications.The resultant immunoadhesins can have advantages usually found in monoclonal antibodies such as ease of purification, high binding affinity and effector functions.

View Article: PubMed Central - PubMed

Affiliation: 1. Antibody Therapy Unit, Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA;

ABSTRACT

Background: The mucin MUC16 expresses the repeating peptide epitope CA125 that has been known for decades to be a well-validated cancer marker that is overexpressed on the cell surface of ovarian cancers and other malignant tumors. In spite of recent efforts to make mouse monoclonal antibodies to MUC16 to treat ovarian cancer, a human monoclonal antibody against this mucin has not been described. MUC16 interacts with mesothelin, a protein that mediates heterotypic cancer cell adhesion, indicating that MUC16 and mesothelin play an important role in the peritoneal implantation and metastasis of ovarian tumors. Therefore, a suitable candidate for therapeutic targeting of MUC16 would functionally block the interaction of MUC16 and mesothelin.

Methodology/principal findings: Here we report the generation of a novel immunoadhesin, HN125, against MUC16 that consists of a functional MUC16 binding domain of mesothelin (IAB) and the Fc portion of a human antibody IgG1. The yield for purified HN125 proteins is over 100 µg/mL of HEK-293 culture supernatant. We show that HN125 has high and specific affinity for MUC16-expressing cancer cells by flow cytometry and immunohistochemistry. HN125 has the ability to disrupt the heterotypic cancer cell adhesion mediated by the MUC16-mesothelin interaction. Moreover, it elicits strong antibody-dependent cell mediated cytotoxicity against MUC16-positive cancer cells in vitro.

Conclusion/significance: This report describes a novel human immunotherapeutic agent highly specific for MUC16 with potential for treating ovarian cancer and other MUC16-expressing tumors. Because of its lower immunogenicity in patients, a fully human protein is the most desirable format for clinical applications. We believe that the methods developed here may apply to the generation of other tumor-targeting immunoadhesins when it is difficult to obtain a human monoclonal antibody to a given antigen for clinical applications. The resultant immunoadhesins can have advantages usually found in monoclonal antibodies such as ease of purification, high binding affinity and effector functions.

No MeSH data available.


Related in: MedlinePlus