Detection of EphA3 as a Marker of the Presence of a Solid Tumor
The invention provides methods and compositions for detecting non-hematopoietic, non-tumor EphA3-expressing cells in cancer patients and for monitoring the prognosis of patients using EphA3.
1 . A method of identifying a patient who has a solid tumor and is to be treated with a cancer therapeutic, the method comprising:
contacting peripheral blood mononuclear cells present in a sample from a patient that may have a solid tumor with a first antibody that selectively binds to EphA3; and
detecting the percentage of non-hematopoietic, non-tumor peripheral blood mononuclear cells that are EphA3+ to determine if at least 0.01% of non-hematopoietic, non-tumor peripheral blood mononuclear cells express EphA3 on the surface of the cells, where a percentage of at least 0.01% identifies the patient to be treated with a cancer therapeutic.
2 . The method of claim 1 , further comprising determining whether the EphA3 + cells are CD34 − .
3 . The method of claim 1 , further comprising determining whether the EphA3 + cells are CD45 − .
4 . The method of claim 1 , further comprising determining whether the EphA3 + cells express CD44, CD90, and/or KDR.
5 . The method of claim 1 , wherein EphA3 expression on the surface of the cells is detected by flow cytometry.
6 . The method of claim 1 , further comprising contacting the cells with a second antibody that selectively binds to EphA3 at an epitope that is different than the epitope to which the first antibody binds.
7 . The method of claim 6 , wherein the second antibody is labeled with the same detectable label as the first antibody.
8 . The method of claim 1 , wherein the patient has a breast carcinoma, a lung adenocarcinoma, a lung squamous cell carcinoma, a colon adenocarcinoma, a renal cell carcinoma, a transitional cell carcinoma, a prostate adenocarcinoma, or a melanoma.
9 . The method of claim 1 , further comprising administering a cancer therapeutic agent to the patient.
10 . The method of claim 9 , wherein the cancer therapeutic agent is an anti-vascular therapeutic agent
11 . The method of claim 10 , wherein the anti-vascular therapeutic agent is a vascular endothelial growth factor (VEGF) antagonist or an antibody that activates EphA3.
12 . The method of claim 9 , wherein the cancer therapeutic agent in an antibody that selectively binds EphA3.
13 . A method of monitoring efficacy of a cancer therapeutic agent, the method comprising:
contacting peripheral blood mononuclear cells present in a sample with a first antibody that selectively binds to EphA3, wherein the sample is obtained from a patient that has a solid tumor following a treatment with the cancer therapeutic agent, where the patient was determined to have at least 0.01% of peripheral blood mononuclear cells that express EphA3 before treatment with the cancer therapeutic agent; and
determining the percentage of non-hematopoietic, non-tumor peripheral blood mononuclear cells that are EphA3+ on the surface of the cells to detect if less than 0.01% of non-hematopoietic, non-tumor mononuclear cells express EphA3, where a reduction in the number of EphA3-positive cells by at least 20% relative to the level before treatment with the cancer therapeutic agent is indicative of therapeutic efficacy of the cancer therapeutic agent.
14 . The method of claim 13 , wherein the cancer therapeutic agent is an anti-vascular-therapeutic agent.
15 . The method of claim 14 , wherein the anti-vascular therapeutic agent is a VEGF antagonist or an antibody that activates EphA3.
16 . The method of claim 13 , wherein the cancer therapeutic agent is an antibody that selectively binds EphA3 + .
17 . The method of claim 13 , wherein the cancer therapeutic agent is a therapeutic antibody that selectively binds to EphA3 and the step of determining the level of EphA3+ non-hematopoietic, non-tumor cells comprises contacting the cells with an antibody that binds to an epitope different to the epitope to which the therapeutic antibody binds.
18 . The method of claim 13 , wherein the patient has a breast carcinoma, a lung adenocarcinoma, a lung squamous cell carcinoma, a colon adenocarcinoma, a renal cell carcinoma, a transitional cell carcinoma, a prostate adenocarcinoma, or a melanoma.
19 . A kit for detecting the presence of non-hematopoietic cells in a sample, wherein the kit comprises:
a first antibody that selectively binds to an EphA3 epitope and a second antibody that selectively binds to a different EphA3 epitope; or
a first antibody that selectively binds to an EphA3 epitope and a second antibody that selectively binds to a different EphA3 epitope, and an antibody that binds to a surface marker selected from the group consisting of CD34, CD45, CD90, and KDR.