Carboplatin kills cancer cells mainly through induction of DNA damage (drug-DNA adducts). The goal of this clinical trial is to determine if chemoresistance to carboplatin can be identified by measuring carboplatin-induced DNA monoadducts, the precursor of Pt-DNA diadducts or crosslinks, from subtherapeutic drug doses given prior to the initiation of chemotherapy. We hypothesize that low levels of carboplatin-DNA monoadducts and rapid drug-DNA adduct repair correlate with chemoresistance. A highly sensitive technology, called accelerator mass spectrometry (AMS), will be used to measure carboplatin-DNA monoadducts from patient samples. AMS can measure C-14 at the attomole level in specimens of milligram size. In this study, patients will receive one non-toxic "microdose" (defined as 1/100th the therapeutic dose) of C-14-labeled carboplatin. Blood specimens will be drawn for determination of carboplatin-DNA monoadduct formation and repair in peripheral blood mononuclear cells (PBMC), and pharmacokinetics (PK) will be determined from serum ultrafiltrate. In patients microdosed prior to providing tumor samples, a few milligrams of leftover tumor biopsy/resection specimens will be analyzed for formation of carboplatin-DNA monoadducts. Patients will subsequently receive carboplatin-based chemotherapy. The levels of microdose-induced carboplatin-DNA monoadducts will be correlated with response to chemotherapy. Some blood and biopsy samples will be assayed by RT-PCR for several putative resistance markers at the mRNA level. Side effects will also be monitored and compared to the AMS data. This trial will also utilize PK, DNA repair and pharmacogenomics data in order to determine some of the underlying chemoresistance mechanisms.
Full record on ClinicalTrials.gov (NCT ID NCT01261299).