Special Project Grant Awarded to Carl Koschmann

A DMG tumor’s response to therapy is usually measured by hand outlining the tumor margin via radiographic imaging such as an MRI. If a tumor is found to progress, clinicians can suggest rapid adjustments to treatment to best suit the patient. Unfortunately, MRI scans can be technically difficult to interpret (especially in the case of diffuse gliomas). On top of this, radiation or other treatment induced inflammation can masquerade as tumor growth (known as “pseudo-progression”), further complicating interpretation and delaying proper treatment. Recent work in our lab has discovered that circulating tumor DNA (cf-tDNA) in cerebrospinal fluid (CSF) and plasma can be quantified using droplet digital polymerase chain reaction (ddPCR) and might offer a more quantitative and objective measure of a tumor’s response to treatment. In a recent early phase trial with ONC201, we were able to detect H3K27M cf-tDNA in 53/62 plasma samples (sensitivity of 85.4%) and 28/29 CSF samples (sensitivity of 96.5%). While both MRIs and CSF analysis require site visits and general anesthesia, plasma does not, and could be collected off-site and shipped overnight for analysis. This “send-out” would greatly reduce the travel burden and enable clinicians to remotely monitor progress between visits. However, our prior ddPCR tests remain “research grade” as they are performed in our lab on clinical trial specimens, and are not designed for clinical-grade repeatability and reliability. Currently, there are no CLIA or FDA approved molecular tests for histone mutant quantification that are sensitive enough to track low-levels of tumor DNA (<0.5%) in patient plasma, further motivating development of a sensitive, clinical-grade histone mutation surveillance assay. We will address the above issues by developing histone mutant ddPCR assays (H3F3A K27M, HIST1H3B K27M, H3F3A G34R), new protocols improving repeatability and reliability, and by validating each assay in a Clinical Laboratory Improvement Amendments (CLIA)-certified laboratory within the University of Michigan.