Use of germ-line single nucleotide polymorphisms (SNPs) in drug transporters (ABCG2/ABCB1) and tubulin (TUBB4) to predict survival in patients with metastatic castrate-resistant prostate cancer (CRPC) receiving docetaxel.
58 Background: Multiple treatment options now exist for metastatic CRPC patients (pts). Germ-line SNPs in docetaxel (D) transport, metabolism, binding site, and degradation genes may contribute to variability in outcomes observed in D treated CRPC pts. Methods: Between 1/07 and 10/08, all PCa pts seen in the Indiana University Simon Cancer Center oncology clinics were approached for recruitment to the Prostate Cancer Genetic Risk Evaluation of SNPs Study (PROGRESS). Participants completed a demographic and clinical questionnaire and provided a blood sample. Only CRPC pts treated with D were included in this analysis. Germ-line DNA was analyzed for SNP genotyping on a 128-SNP chip using a TaqMan OpenArray GT Kit (Applied Biosystems). The chip included genes critical to D signaling, transport, and elimination with minor allele frequencies > 5%. Pts were followed for progression-free (PFS) and overall survival (OS). Univariable analyses were performed to identify significant associations between SNP genotype, clinical parameters, and PFS and OS outcomes. Results: 60 pts with metastatic CRPC initiated on D enrolled. Demographics included: age (median) – 69 yrs, ECOG PS 0– 40%, prostate specific antigen (PSA) (median) – 129.9 ng/ml, PSA doubling time (median) – 1.8 months, visceral mets –25%. No clinical parameters were associated with PFS and OS. Significant SNP associations are summarized below. Conclusions: Differences in germ-line ABCG2, ABCB1, and TUBB4 SNPs may contribute to variation in clinical outcomes in CRPC pts treated with D. [Table: see text] [Table: see text]