Binding agents
Compositions and methods relating to epitopes of sclerostin protein, and sclerostin binding agents, such as antibodies capable of binding to sclerostin, are provided.
1. A method of isolating an antibody that binds sclerostin of SEQ ID NO: 1, the method comprising (a) performing a cross-blocking assay with (i) a first antibody and (ii) a second antibody comprising heavy chains of SEQ ID NO: 209 and light chains of SEQ ID NO: 205 in the presence of sclerostin of SEQ ID NO: 1, and (b) isolating a first antibody that competes with the second antibody for binding to sclerostin.
2. The method of claim 1 , wherein the cross-blocking assay is an ELISA assay and a reduction of between 60% and 100% of sclerostin detection signal in the presence of (i) and (ii) as compared to the sclerostin detection signal obtained in the presence of (i) or (ii) alone indicates that the first antibody competes with the second antibody for binding to sclerostin.
3. The method of claim 2 , wherein the reduction in the amount of sclerostin detection signal is between 80% and 100%.
4. The method of claim 1 , wherein the cross-blocking assay is a surface plasmon resonance assay and a recorded binding of between 80% and 4% of the maximum theoretical binding between (i) and sclerostin in the presence of (ii) indicates that the first antibody competes with the second antibody for binding to sclerostin.
5. The method of claim 4 , wherein the recorded binding is between 70% and 4% of the maximum theoretical binding.
6. The method of claim 1 , wherein the second antibody demonstrates a binding affinity for sclerostin of SEQ ID NO: 1 of less than or equal to 1×10 −7 M.
7. The method of claim 6 , wherein the second antibody demonstrates a binding affinity for sclerostin of SEQ ID NO: 1 of less than or equal to 1×10 −9 M.
8. The method of claim 1 , further comprising screening the first antibody in a sclerostin neutralization assay.
9. The method of claim 8 , wherein the sclerostin neutralization assay comprises (i) contacting osteoblast-lineage cells with the first antibody in the presence of sclerostin and (ii) measuring mineralization, wherein an increase in mineralization indicates that the first antibody neutralizes sclerostin activity.
10. The method of claim 8 , wherein the sclerostin neutralization assay comprises (i) administering the first antibody to a non-human mammal, and (ii) measuring a serum anabolic marker, a histomorphometric marker of bone formation, bone mineral density, bone mineral content, bone mass, bone quality, or bone strength.