Antibodies and immunotoxins that target human glycoprotein NMB
Inventors
Kuan, Chien-Tsun • Bigner, Darell D • Pastan, Ira H
Assignees
National Institutes of Health NIH • Duke University
Publication Number
US-8445216-B2
Publication Date
2013-05-21
Expiration Date
2026-10-31
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Abstract
The invention provides high affinity antibodies suitable for forming Immunotoxins that inhibit the growth of cells expressing human glycoprotein NMB, including glioblastoma multiform cells, anaplastic astrocytoma cells, anaplastic oligodendroglioma cells, oligodendroglioma cells, and melanoma cells.
Core Innovation
The invention provides high affinity antibodies against human glycoprotein NMB (GPNMB) and methods for using them, including isolated polypeptides comprising antibody heavy and light chain variable regions with specifically defined complementarity determining regions (CDRs). These antibodies are capable of forming immunotoxins that inhibit the growth of cells expressing human glycoprotein NMB, such as glioblastoma multiform cells, anaplastic astrocytoma cells, anaplastic oligodendroglioma cells, oligodendroglioma cells, and melanoma cells.
The problem being solved is the difficulty in effectively targeting cancer cells expressing GPNMB with immunotoxins. Although previous monoclonal antibodies against GPNMB were generated, they did not internalize well into target cells, making them unsuitable for delivering cytotoxic agents that require internalization to kill the target cell. There is a need for antibodies that have both high affinity and efficient internalization properties to enable effective immunotoxin therapy against GPNMB-expressing cancers.
The invention addresses this problem by providing novel antibodies, such as the G49 antibody and its variants (e.g., L22, B307, 902V), which have high affinity for GPNMB and internalize effectively into target cells. These antibodies, when made into immunotoxins with cytotoxins like Pseudomonas exotoxin A (PE) variants, demonstrate potent cytotoxicity selectively against GPNMB-expressing cells while sparing GPNMB-negative cells. The antibodies also maintain sufficient surface residence time to be useful for delivering detectable labels for diagnostic purposes.
Claims Coverage
The patent includes a group of independent claims focusing on methods of detecting cancer cells expressing human glycoprotein NMB using chimeric molecules comprising specific antibody variable regions and detectable labels.
Use of specific antibody variable region sequences for targeting
The chimeric molecule comprises a polypeptide including antibody heavy chain variable region (VH) and light chain variable region (VL), each having four framework regions (FRs 1-4) and three complementarity determining regions (CDRs 1-3), where VH CDR1 has a sequence selected from SEQ ID NOs:22-28, VH CDR2 is SEQ ID NO:29, VH CDR3 is SEQ ID NO:30, VL CDR1 is SEQ ID NO:31, VL CDR2 is SEQ ID NO:32, and VL CDR3 has a sequence selected from SEQ ID NOs:33-37.
Incorporation of a detectable label for detection method
The chimeric molecule further includes a detectable label that enables detection of the presence of the cancer cell expressing human glycoprotein NMB after binding.
Specific sequence embodiments for improved detection
In particular embodiments, the CDR1 of the VH chain has the sequence of SEQ ID NO:23, 24, 25, or 26, and the CDR3 of the VL chain has the sequence of SEQ ID NO:34.
Framework region sequences of antibody G49 used in detection
The framework regions 1-4 of the VH and VL chains correspond respectively to those of antibody G49 as shown in SEQ ID NO:1 (VH) and SEQ ID NO:12 (VL).
The independent claims cover methods for detecting cancer cells expressing human glycoprotein NMB by using chimeric molecules that incorporate specified antibody variable region sequences with defined CDRs and framework regions, combined with a detectable label to enable identification of targeted cells. Specific sequence variants particularly using the G49 antibody framework are claimed for effective detection applications.
Stated Advantages
The antibodies have high affinity and effective internalization into GPNMB-expressing cells, improving immunotoxin delivery and cytotoxicity.
Immunotoxins using these antibodies selectively kill GPNMB-expressing cancer cells while sparing non-expressing cells.
The antibodies maintain surface binding properties suitable for delivering detectable labels, enabling diagnostic imaging and detection of GPNMB-expressing cells.
The improved affinity increases tumor targeting efficiency, facilitating better therapeutic and diagnostic outcomes.
Smaller antibody fragments such as scFv or dsFv improve tumor penetration and reduce side effects through faster clearance.
Documented Applications
Inhibiting the growth of cancer cells expressing human glycoprotein NMB, including glioblastoma multiforme cells, anaplastic astrocytoma cells, anaplastic oligodendroglioma cells, oligodendroglioma cells, and melanoma cells, by contacting these cells with immunotoxins comprising the anti-GPNMB antibodies and a cytotoxin such as Pseudomonas exotoxin A.
Detecting the presence of cancer cells expressing human glycoprotein NMB by contacting cells with chimeric molecules comprising the anti-GPNMB antibodies and a detectable label and detecting the bound label.
Purging GPNMB-expressing cells from biological samples or cell cultures by using cytotoxic immunotoxins based on the described antibodies.
Use of the antibodies and immunoconjugates in imaging or labeling GPNMB-expressing cells in biological samples or patients for diagnostic purposes.
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