Compositions and methods for diagnosing and monitoring ovarian cancer progression and treatment

A method for differentiating platinum-sensitive metastatic ovarian cancer from platinum-resistant metastatic ovarian cancer, said method comprising administering an effective amount of a platinum-based chemotherapeutic agent to a subject with ovarian cancer, determining the level of VCAM-1 expression in said subject following said administration and comparing said VCAM-1 level to the level of VCAM-1 expression in said subject prior to administration of said chemotherapeutic agent or to a standard value of VCAM-1 levels, wherein said VCAM-1 levels in said subject are determined by administering to said subject an effective amount of a VCAM-1 imaging probe that binds to VCAM-1 or contacting a biopsy from said subject with an effective amount of a VCAM-1 imaging probe, and then determining the amount of VCAM-1 levels in said subject or in said biopsy, wherein said VCAM-1 probe is a multimeric peptide ligand complex comprising SEQ ID NO:1, each of said peptides is coupled to polyethylene glycol, said polyethylene glycol is coupled to a chelating agent via a linking agent, and optionally at least one imaging agent is coupled to said chelating agent, wherein a decrease in VCAM-1 levels following said administration is an indication that the ovarian cancer is platinum-sensitive and no change in VCAM-1 levels is an indication that the ovarian cancer is platinum-resistant, thereby differentiating platinum-sensitive metastatic ovarian cancer from platinum-resistant metastatic ovarian cancer.