ASCO 2017: The plasma lipidome in castration-resistant prostate cancer

Chicago, IL ( Biomarker studies of metastatic castration-resistant prostate cancer (mCRPC) have mainly focused on changes in the cancer, however, the host environment and its interactions with cancer is increasingly important, especially given the increasing association of prostate cancer (PC) outcomes and obesity. However, the association of circulating lipids with the clinical outcome of CRPC is unknown and has not been studied. Dr. Lisa Horvath presented an interesting study attempting to find associations between the plasma lipidome and clinical outcome in CRPC. 

Plasma samples were obtained from a Phase 1 discovery cohort of 96 CRPC patients before and after the first cycle of docetaxel chemotherapy. Lipidomic profiling of the plasma samples was performed by liquid chromatography and electrospray ionisation-tandem mass spectrometry. Results were subsequently assessed in a Phase 2 validation cohort of 63 CRPC patients. 

Lipidomic profiling detected 323 lipid species in plasma samples from the Phase 1 cohort. Patients were classified into two subgroups with significant survival differences according to their baseline lipidomic profiles (median overall survival 13.7 vs 21.7 months; HR 2.31, 95% CI 1.44-3.68, p = 0.0005). The baseline levels of 46 lipids were individually prognostic (p < 0.01) and predominantly sphingolipids. A prognostic three-lipid signature was derived (ceramide (d18:1/24:1), sphingomyelin (d18:2/16:0), phosphatidylcholine (16:0/16:0)) (11.7 versus 21.7 months, p = 0.00001; HR 2.94, 95% CI 1.80-4.81, p = 0.00002). The signature was associated with shorter overall survival in the Phase 2 cohort (HR 4.78, 95% CI 2.06-11.1, p = 0.0003), and was an independent prognostic factor when modeled together with clinicopathologic factors and metabolic characteristics (BMI, cholesterol and triacylglycerol). The AUC of ROC analysis of 12 month survival for a clinicopathologic model (AUC 0.70, 95% CI 0.54-0.87, p = 0.03) was enhanced by the addition of the 3-lipid signature (AUC 0.73, 95% CI 0.57-0.89, p = 0.01). 

In summary, this novel study is the first to comprehensively profile the plasma lipidome of men with CRPC using cutting-edge lipidomic profiling technology, to identify a plasma lipid signature that can reproducibly predict outcome in CRPC and can improve on clinicopathologic models. Therapeutic modulation of the levels of these lipids by targeting their metabolic pathways may improve patient outcome.

Presented By: Lisa Horvath, MBBS, FRACP, PhD, Chris O'Brien Lifehouse, Sydney, Australia

Written By: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre, Toronto, Ontario, Canada
Twitter: @GoldbergHanan

at the 2017 ASCO Annual Meeting - June 2 - 6, 2017 - Chicago, Illinois, USA