Method for identifying targets for precision cancer therapy

Abstract

Disclosed herein is Differential Subclone Eradication and Resistance Analysis (DSER), a method developed to identify molecular targets for improved therapy by direct comparison of genomic features of eradicated and resistant subclones in pre- and post-treatment samples from a patient with BRCA2-deficient metastatic prostate cancer. FANCI and EYA4 were identified as candidate DNA repair-related targets for converting subclones from resistant to eradicable, and RNAi-mediated depletion of FANCI confirmed it as a potential target. The EYA4 alteration was associated with adjacent L1 transposon insertion during cancer evolution upon treatment. L1 activation was inhibited by the antiretroviral drug azidothymidine. In conclusion DSER provides an informative intermediate step toward effective precision cancer medicine, especially in cases with dramatic but temporary metastatic tumor regression. L1 transposon activation may be a modifiable source of cancer genomic heterogeneity, suggesting the potential of leveraging newly discovered triggers and blockers of L1 activity to overcome therapy resistance.