e17582 Background: Cabazitaxel is a semi-synthetic derivative of a natural taxoid approved for the treatment of mCRPC patients (pts) after failure to docetaxel. Despite its proven efficacy, there is variability in the response, progression-free survival (PFS) and overall survival (OS) of pts. Changes in the genetic constitution of the individual such as the SNPs could explain this variability. The aim of this study was to evaluate the impact of certain SNPs in cabazitaxel activity. Methods: Clinical data from 67 mCRPC pts treated with cabazitaxel between March 2011 and October 2016 were collected. DNA was isolated from formalin fixed paraffin-embedded tumor samples. 56 SNPs in 5 genes related with metabolism and/or mechanism of action of cabazitaxel (CYP3A4, CYP3A5, ABCB1, TUBB1, CYP2C8) were chosen based on their Minor Allele Frequency, linkage disequilibrium and information from dbSNP and analyzed by TaqMan OpenArray (Lifetech). The presence/absence of mutant alleles of the selected SNPs was correlated with clinical features, progression free survival (PFS) and overall survival (OS) of prostate cancer. Chi-square test and Kaplan-Meier with log-rank test were used for statistical analyses. Results: The median age was 61 years (range 44-82). 56.7% (n = 38) had a Gleason score ≥8 and 94% had received docetaxel in first line. Type of response to cabazitaxel was associated with median OS (Partial response = 24.35 months, Stable disease = 11.16 months, Progression disease = 5.8 months; p= 0.045). Univariate analysis, showed worsed OS at 1 year for wild type status of SNP rs151352 (OR = 4, 95%CI 1.27-12.58, p= 0.029). In addition, two SNPs (rs11773597, rs1202186) were associated with radiological response to cabazitaxel ( p= 0.031 and p= 0.030 respectively). Other 7 SNPs (rs11773597, rs2235040, rs1045642, rs1419745, rs1202170, rs6949448, rs11572093) were associated ( p<0.05) with Gleason score, pain, PSA doubling time, febrile neutropenia and asthenia. Conclusions: A particular SNP profile could be predictive of efficacy and related with toxicity in mCRPC population treated with cabazitaxel after progression to docetaxel. These outcomes become particularly relevant in patient selection given the recent results of the CARD trial.
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