PARP and Platinum 




Poly ADP Ribose Polymerase inhibitors (PARPi) are a class of drugs that serve as targeted therapy for cancers with Homologous Recombination DNA Repair Deficiency (HRD), reliant on non-homologous end joining (NHEJ).  HRD can occur by inactivation of related genes such as BRCA through mutations or silencing. PARPi bind to the PARP enzyme, preventing its repair of single strand DNA nicks.  The accumulation of DNA nicks results in double stranded DNA (dsDNA) breaks which proves lethal in cells using to repair dsDNA breaks.  PARPi mediated synthetic lethality has been demonstrated durable responses in sub-population of patients with HRD. The key is identifying those patients who are likely to respond.

Epic HRD Test: Identification of HRD+ tumors through a liquid biopsy

Epic Sciences has developed the Epic HRD Test, to identify patients with HRD from a simple peripheral blood draw through single cell imaging of individual circulating tumor cells (CTCs). Parallel high content image analysis and single cell sequencing characterized the observed morphological differences between cells sequenced with high genomic instability, a signature of HRD, vs. those with low genomic instability. Subsequently, the Epic Sciences team developed a propriety algorithm that can predict cells with high genomic instability and identifies an HRD phenotype (figure 1, as presented at ASCO 2016) based on image analysis alone.

This new test will facilitate both clinical trials and drug discovery by:

  • Quickly identifying HRD positive patients (TAT < 1 week from blood draw)
  • Identifying more HRD positive patients than a traditional genomic assay (~32% prevalence of marker in mCRPC)
  • Minimally invasive, liquid biopsy allows for a time relevant analysis of HRD status and longitudinal monitoring of therapeutic efficacy
  • Single cell analysis can differentiate germline vs somatic alterations and provide insight into % of active tumor burden with HRD+ vs. other driver mechanisms

Time to PSA Progression

PSA Response (% with >50% PSA Decline)

RAD51 Staining

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All of Epic Sciences’ offerings including our new Epic HRD Test can be used to develop a companion diagnostic assay to ensure the right treatment for the right patient at the right time. Request more information on CDx capabilities