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A humanized single-chain Fv fragment with high targeting potential against human malignant gliomas
T Ohtomo1, H Kawata, Y Sekimori
1Chugai Pharmaceutical Co., Ltd., Fuji Gotemba Research Laboratories, Shizuoka, Japan.
Abstract:
A humanized ONS-M21 antibody (hM21) against human medulloblastoma and glioma cells was engineered as a single-chain Fv fragment (scFv), and its ability to internalize into tumor cells was evaluated by conjugation with ricin A. The scFv of hM21 (schM21) was easily purified from E.coli by one-step affinity column chromatography. Purified schM21 bound to a medulloblastoma ONS-76 cell with almost equal antigen-binding activity of hM21-Fab fragment. Furthermore, the schM21-ricin A conjugate inhibited the growth of ONS-76 cells, but not that of antigen-negative hepatoma HuH-7 cells, suggesting that the schM21 can be internalized after binding to antigen-positive cells. Thus, schM21 could be expected to act as a novel carrier of diagnostic and therapeutic agents for brain tumors.
Insights
A novel engineered antibody fragment (schM21) effectively targets and enters medulloblastoma and glioma cells. This fragment shows potential as a carrier for brain tumor diagnostics and therapeutics.
Area of Science:
- Oncology
- Immunology
- Biotechnology
Background:
- Medulloblastoma and glioma are aggressive brain tumors with limited treatment options.
- Targeted therapies require specific delivery mechanisms to tumor cells.
- Antibody engineering offers a route to develop such delivery systems.
Purpose of the Study:
- To engineer a humanized antibody fragment (schM21) targeting medulloblastoma and glioma cells.
- To evaluate the internalization capability of schM21 into tumor cells.
- To assess the therapeutic potential of schM21 as a drug delivery vehicle.
Main Methods:
- Engineering of a humanized ONS-M21 antibody (hM21) into a single-chain Fv fragment (schM21).
- Purification of schM21 from E. coli using one-step affinity chromatography.
- Conjugation of schM21 with ricin A to assess internalization and cytotoxic effects.
- In vitro testing on medulloblastoma (ONS-76) and hepatoma (HuH-7) cell lines.
Main Results:
- schM21 was successfully purified and demonstrated antigen-binding activity comparable to the hM21-Fab fragment.
- The schM21-ricin A conjugate inhibited the growth of antigen-positive ONS-76 cells.
- No significant growth inhibition was observed in antigen-negative HuH-7 cells, confirming target specificity.
- These findings suggest successful internalization of schM21 into tumor cells.
Conclusions:
- Engineered single-chain Fv fragment (schM21) exhibits specific binding and internalization into medulloblastoma and glioma cells.
- schM21 demonstrates potential as a novel carrier for diagnostic and therapeutic agents in brain tumor treatment.
- Further development of schM21-based conjugates could lead to improved targeted therapies for brain cancers.