Antibodies to GRP78

1. An isolated antibody that binds to 78-kDa glucose-regulated protein (GRP78), wherein the antibody comprises a heavy chain variable domain comprising a CDR1, CDR2, and a CDR3, wherein the heavy chain variable domain CDR1 comprises SEQ ID NO: 15, the heavy chain variable region domain CDR2 comprises SEQ ID NO:16, and the heavy chain variable region domain CDR3 comprises SEQ ID NO:17; and a light chain variable domain comprising a CDR1, CDR2, and CDR3, wherein the light chain variable domain CDR1 comprises SEQ ID NO:18, the light chain variable region domain CDR2 comprises SEQ ID NO:19, and the light chain variable region domain CDR3 comprises SEQ ID NO:20.

2. The antibody of claim 1 , wherein the antibody recognizes an epitope within an amino acid sequence selected from the group consisting of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, or SEQ ID NO:4.

3. The antibody of claim 1 , wherein the antibody is selected from the group consisting of a humanized antibody, a single chain variable fragment (scFv) antibody, an antigen-binding antibody fragment, or a chimeric antibody.

4. The antibody of claim 1 , wherein the antibody is conjugated directly or indirectly to a payload selected from the group consisting of a therapeutic agent, an imaging agent, or a combination thereof.

5. A method of enhancing radiotherapy in a subject comprising administering a pharmacologically effective amount of the antibody of claim 4 to the subject, such that radiotherapy is enhanced.

6. The method of claim 5 , further comprising administering ionizing radiation to the subject.

7. The method of claim 5 , further comprising imaging the subject.

8. The method of claim 5 , wherein, the therapeutic agent is an antineoplastic agent.

9. A method of imaging cancer in a subject comprising conjugating the antibody of claim 1 to an imaging agent and administering a pharmacologically effective amount of the conjugated antibody to the subject, and imaging cancer in the subject.