Methods for Determining the Likelihood of Survival and for Predicting Likelihood of Metastasis in Cancer Patients

A method of treating a subject with a HER2-positive cancer, comprising:

• (a) obtaining a sample of a HER2 positive tumor from a subject diagnosed with a HER2 positive cancer, wherein the subject does not have a detectable brain metastasis;
• (b) providing a p95-HER2 monoclonal antibody that specifically binds to p95-HER2 protein having a first amino acid corresponding to methionine 611 of HER2 protein, wherein the p95-HER2 monoclonal antibody does not bind to full length HER2;
• (c) providing a binding compound that binds to the p95-HER2 monoclonal antibody, wherein the binding compound comprises a molecular tag covalently attached thereto via a cleavable linkage;
• (d) quantifying the amount of p95-HER2 in the sample by the steps of (i) incubating the sample with the p95-HER2 monoclonal antibody and the binding compound, (ii) treating the sample with a cleaving agent to release the molecular tag from the binding compound, and (iii) measuring the amount of released molecular tag as indicative of p95-HER2 levels in the sample to determine the amount of p95-HER2 protein in the sample;
• and
• (e) monitoring the subject by performing imaging on the subject's brain at different times after initial diagnosis of the HER2 positive cancer to detect brain metastasis if the amount of p95-HER2 protein in the sample is above a predetermined cutoff amount of p95-HER2 determined in a reference population of subjects having the HER2-positive cancer.