Non-invasive profiling of advanced prostate cancer via multi-parametric liquid biopsy and radiomics
Tissue biopsy is hard to repeat often enough to track treatment response in advanced prostate cancer; this AACR 2020 pilot study from the USC Norris Comprehensive Cancer Center profiled single circulating tumor cells, matched plasma cell-free DNA and CT-scan radiomics together in 23 patients with metastatic castrate-resistant disease.
Presented by USC Norris Comprehensive Cancer Center.
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- Two CTC platforms were run side by side, and their counts tracked each other. Of 19 patients enumerated on both, CellSearch detected CTCs in 12 (63%; median 3 per 7.5 mL) and RareCyte in 14 (74%; median 1 per 7.5 mL); plotted against each other, the two counts gave R² = 0.88.
- Single CTCs and cell-free DNA each carried alterations the other did not. Across the cohort, 48 somatic alterations were identified in CTCs against 18 in cfDNA, spanning AR, TP53, CCND3, FGFR1, ALK and ROS1; of the 14 patients whose single CTCs were recovered, 12 (86%) had detectable somatic mutations in single-cell DNA versus 7 (50%) in matched cfDNA, and where both were sequenced most mutations were distinct rather than shared.
- CT-scan texture tracked CTC burden, reported by the authors as the first such association in metastatic prostate cancer. Radiomic entropy extracted from GLCM maps of bone metastatic lesions was associated with CellSearch CTC counts at an AUC of 0.74, using the FDA-cleared prognostic threshold for that platform of fewer than 5 versus 5 or more CTCs per 7.5 mL.
