Monitoring treatment response to androgen depriviation therapy (ADT) of metastatic prostate cancer patients.
(A+B) Patients, who responded well to the treatment, showed a massive decrease in ctDNA levels. After 2 months of therapy neither SCNAs nor the mutations in CTNNB1 and TP53, respectively could be observed. Moreover, the genomewide z-scores established with mFAST-SeqS, which correlated with ctDNA levels, dropped dramatically. (C) This patient did not respond to the therapy. In contrast elevated levels of ctDNA were observed after 6 months of treatment, which is reflected in higher log-2 ratios of the SCNAs and an increase of a somatic BRCA1 mutation from 47.4% to 79.5%. Treatment failure could be attributed to a high level amplification of the AR gene, which is known to be associated with resistance to ADT and the development of castration resistant prostate cancer.