Multimodal Approach to Outcome Prediction in Metastatic Castration-Resistant Prostate Cancer by Integrating Functional Imaging and Plasma DNA Analysis.

PURPOSE

Biomarkers for treatment personalization in metastatic castration-resistant prostate cancer (mCRPC) could help improve patient outcomes. Multiple tests on blood have reported associations with poorer outcome, including serum lactate dehydrogenase (LDH), chromogranin A (CGA), neutrophil:lymphocyte ratio (NLR), and, recently, copy number (CN) of androgen receptor (AR) in plasma DNA. Biologic data suggest an association between choline uptake and AR signaling. We aimed to integrate 18-fluorocholine (FCH) uptake on positron emission tomography/computed tomography (PET/CT) scanning with plasma CN and other routinely obtained circulating biomarkers to evaluate their association with outcome.

MATERIALS AND METHODS

We determined plasma CN by digital droplet polymerase chain reaction from 105 mCRPC samples collected before abiraterone (n = 65) or enzalutamide (n = 40) therapy in the before (n = 26) and after (n = 79) chemotherapy settings. Pretreatment serum LDH, CGA, and NLR were also measured. FCH-PET/CT scan was performed at baseline, and maximum standardized uptake value (SUV), total lesion activity (TLA), and metabolic tumor volume (MTV) were calculated. Main end points were the correlation of FCH-PET/CT parameters with circulating biomarkers and their impact on outcome.

RESULTS

Plasma CN gain was observed in 27 patients (25.7%), and it correlated significantly with higher median SUV, TLA, and MTV values ( < .001). Kaplan-Meier curves showed significantly worse progression-free survival and overall survival in patients with plasma gain and higher SUV, TLA, and MTV values ( < .001 in each prognostic group). Conversely, no association was reported for prostate-specific antigen response. On multivariable analysis of overall survival, we showed as independent factors gain (hazard ratio [HR], 1.92; 95% CI, 1.07 to 3.47; = .029), presence of visceral metastasis (HR, 3.04; 95% CI, 1.66 to 5.58; = < .001), LDH (HR, 2.95; 95% CI, 1.72 to 5.05; < .001), NLR (HR, 3.51; 95% CI, 2.14 to 5.74; < .001), serum CGA (HR, 3.36; 95% CI, 1.99 to 5.67; < .001), and MTV (HR, 2.09; 95% CI, 1.25 to 3.50; = .005).

CONCLUSION

Our results indicate the potential usefulness of integrating functional imaging with plasma DNA analysis and other noninvasive biomarkers as a tool to improve treatment selection for CRPC. A larger prospective evaluation is warranted.