Olaparib capsules 400mg every 12 hours on days 1 to 7/carboplatin AUC5 is safe and has activity in gBRCAm BrCa/OvCa patients. Exploratory translational studies indicate pretreatment tissue FOXO3a expression may be predictive for response to therapy, requiring prospective validation.

Mechanisms regulating DNA repair processes remain incompletely defined. Here, the circadian factor CRY1, an evolutionally conserved transcriptional coregulator, is identified as a tumor specific regulator of DNA repair. Key findings demonstrate that CRY1 expression is androgen-responsive and associates with poor outcome in prostate cancer. Functional studies and first-in-field mapping of the CRY1 cistrome and transcriptome reveal that CRY1 regulates DNA repair and the G2/M transition. DNA damage stabilizes CRY1 in cancer (in vitro, in vivo, and human tumors ex vivo), which proves critical for efficient DNA repair. Further mechanistic investigation shows that stabilized CRY1 temporally regulates expression of genes required for homologous recombination. Collectively, these findings reveal that CRY1 is hormone-induced in tumors, is further stabilized by genomic insult, and promotes DNA repair and cell survival through temporal transcriptional regulation. These studies identify the circadian factor CRY1 as pro-tumorigenic and nominate CRY1 as a new therapeutic target.

PARP‐1 holds major functions on chromatin, DNA damage repair and transcriptional regulation, both of which are relevant in the context of cancer. Here, unbiased transcriptional profiling revealed the downstream transcriptional profile of PARP‐1 enzymatic activity. Further investigation of the PARP‐1‐regulated transcriptome and secondary strategies for assessing PARP‐1 activity in patient tissues revealed that PARP‐1 activity was unexpectedly enriched as a function of disease progression and was associated with poor outcome independent of DNA double‐strand breaks, suggesting that enhanced PARP‐1 activity may promote aggressive phenotypes. Mechanistic investigation revealed that active PARP‐1 served to enhance E2F1 transcription factor activity, and specifically promoted E2F1‐mediated induction of DNA repair factors involved in homologous recombination (HR). Conversely, PARP‐1 inhibition reduced HR factor availability and thus acted to induce or enhance “BRCA‐ness”. These observations bring new understanding of PARP‐1 function in cancer and have significant ramifications on predicting PARP‐1 inhibitor function in the clinical setting.

Loss of the retinoblastoma (RB) tumor suppressor protein is a critical step in reprogramming biological networks that drive cancer progression, although mechanistic insight has been largely limited to the impact of RB loss on cell cycle regulation. Here, isogenic modeling of RB loss identified disease stage-specific rewiring of E2F1 function, providing the first-in-field mapping of the E2F1 cistrome and transcriptome after RB loss across disease progression. Biochemical and functional assessment using both in vitro and in vivo models identified an unexpected, prominent role for E2F1 in regulation of redox metabolism after RB loss, driving an increase in the synthesis of the antioxidant, glutathione, specific to advanced disease. These E2F1-dependent events resulted in protection from reactive oxygen species (ROS) in response to therapeutic intervention. On balance, these findings reveal novel pathways through which RB loss promotes cancer progression and highlight potentially new nodes of intervention for treating RB-deficient cancers.Research.