1.A mouse antibody that specifically binds the N-WFDC domain of an HE4a polypeptide as set forth in SEQ ID NO: 17, and wherein the antibody is optionally labeled with a detectable marker.

2. The antibody of claim 1, wherein the antibody is a monoclonal antibody, a bispecific antibody, a chimeric antibody, a humanized antibody, a single chain antibody, or an antigen-binding fragment of the  monoclonal, bispecific, chimeric, or humanized,antibody.

3.   The binding agent of claim 1, wherein the binding agent specifically binds the region of an HE4a protein defined by SEQ ID NO:17. 

4.  The antibody of claim 1, wherein the antibody is a monoclonal antibody produced by the hybridoma cell line 12A2, deposited with the ECACC as Patent Deposit No. 10091401.

5.  A fusion protein comprising an N-WFDC domain of an HE4a polypeptide as set forth in SEQ ID NO: 17 or a C-WFDC domain of an HE4a polypeptide as set forth in SEQ ID NO: 19 and a heterologous polypeptide  selected from the group consisting of an affinity tag polypeptide sequence, an immunoglobulin constant region polypeptide, or a polypeptide that directs the fusion protein to a predefined,intracellular, cell membrane, or extracellular location.

6.  A nucleic acid molecule encoding the fusion protein of claim 5.

7.  An expression vector construct comprising the nucleic acid molecule of claim 6.

8.  An isolated host cell comprising the expression vector construct of claim 7.

9.   A kit comprising the antibody of any one of claims 1, 2, or 4, the fusion protein of claim 5, the nucleic acid molecule of claim 6, the expression vector construct of claim 7, or the isolated host cell of claim 8.

10.  The kit of claim 9, wherein the kit comprises the antibody of claim 1, and further comprises a second antibody that specifically binds the C-WFDC domain of an HE4a polypeptide as set forth in SEQ ID NO: 19, the second antibody being optionally detectably labeled.

11.  The kit of claim 9, wherein the kit comprises two antibodies that specifically bind distinct epitopes in the N-WFDC domain of an HE4a protein;or one antibody that specifically binds an epitope in the N-WFDC domain of an HE4a protein and one antibody that specifically binds an epitope in the C-WFDC domain of the HE4a protein.

12.   Use of at least two antibodies specific for an HE4a antigen polypeptide in manufacturing a kit for screening for the presence of an ovarian cancer in a subject or diagnosing a subject with ovarian cancer, wherein the two antibodies specifically bind distinct epitopes in the N-WFDC domain of the HE4a antigen polypeptide as set forth in SEQ ID NO: 17; or one epitope in the N-WFDC domain of an HE4a polypeptide as set forth in SEQ ID NO: 17 and one epitope in the C-WFDC domain of the HE4a antigen polypeptide as set forth in SEQ ID NO: 19,wherein the antibody is used to contact a biological sample from the subjectto determine the presence in the biological sample of an HE4a polypeptide and where in the biological sample containing a molecule that is specifically bound by the at least one antibody indicates the presence of an ovarian cancer or diagnoses subject with ovarian cancer.

13.   The use of claim 12, wherein the kit comprises at least two antibodies, wherein the two antibodies specifically bind: distinct epitopes in the N-WFDC domain of the HE4a antigen polypeptide; distinct epitopes in the C-WFDC domain of the HE4a antigen polypeptide; or one epitope in the N-WFDC domain of an HE4a protein and one epitope in the C-WFDC domain of the HE4a antigen polypeptide.

14.   The use of claim 12 or 13, wherein the molecule naturally occurs in soluble form and the biological sample comprises blood, serum, serosal fluid, plasma, lymph, urine, cerebrospinal fluid, saliva, a mucosal secretion, a vaginal secretion, organ conditioned culture medium, or a lavage fluid.

15.  The use of claim 12, wherein at least one antibody is immobilized on a solid support. 

16.   The use of claim 15, wherein the antibody is used in a two-antibody sandwich assay.

17.  The use of claim 12, wherein the subject is undergoing treatment for ovarian cancer and the kit is used to monitor the course of the disease.