Abstract: Early detection has great promise to reduce the overall morbidity and mortality of cancer by surgical resection and therapeutic intervention on small, localized, genetically homogeneous tumors. This presentation describes our attempts to develop a blood-based test for early cancer in asymptomatic individuals and allow for early intervention and potentially cure of cancer in some patients. Traditionally blood tests for cancer rely on detection of cancer-specific proteins or somatic mutations. While this approach is important for directing therapy and monitoring treatment response in advanced cancers, it is inadequate for early stage tumors because they release very small amounts of DNA into circulation which are simply too low for reliable detection. Here, we will describe a new approach for early detection that evaluates abnormal nucleosome packaging of DNA in cancer cells, and show how this approach can be used to identify early stage malignancies as well as identifying the tissue of origin of the cancer.

Abstract: Immune checkpoint proteins, such as programmed death 1 (PD-1) and its ligand, PD-L1, mediate inhibition of CD8+ effector T cells. Inhibition of the PD-1/PD-L1 interaction with therapeutic antibodies, such as Opdivo® (nivolumab) has emerged as an effective immuno-oncology treatment for several cancers. Currently, the major biomarker used to predict the response to immune checkpoint therapeutics is PD-L1, which is usually measured by immunohistochemistry (IHC) using Formalin-Fixed Paraffin-Embedded (FFPE) tissue specimens. However, IHC provides only semi-quantitative results, and it was reported that about 50% of PD-L1 IHC-positive tumors failed to respond to therapy, while about 15% of PD-L1 IHC-negative tumors did respond to the treatment. Therefore, we evaluated the feasibility of using LC-MS to quantify PD-1 and PD-L1 in FFPE tumor tissues as a complementary analytical platform to IHC. Considering the limited availability and analyte instability concerns with the fleshly frozen tissue samples, there was an increased interest in the utility of FFPE tumor tissues as alternative samples for LC-MS bioanalysis of endogenous protein biomarkers in support of translational research. However, quantitative analysis of endogenous protein, such as PD-1 and PD-L1, in FFPE tumor tissues by LC-MS/MS still poses serious challenges due to low abundance of the protein analytes with potential protein denaturation, fixation and crosslinking in FFPE tissues. This presentation will provide an overview of the methodologies we developed in the LC-MS/MS bioanalysis of endogenous protein biomarkers in FFPE tumor tissues, and discuss the challenges and opportunities associated with the LC-MS/MS bioanalysis of PD-1 and PD-L1 as clinical biomarkers in FFPE tissues for cancer immunotherapy development.

Abstract: An increasing number of studies report that exosomes play critical roles in intercellular communication. While exosomes are essential to maintain physiological conditions, aberrant exosomal communication can lead to the development of cancer, diabetes, and many other diseases. My lab has developed materials to redirect and modulate cellular communication mediated by exosomes for therapeutic applications. Specifically, we have identified RNA-based materials to modulate exosomal function by repackaging them with different types of cargoes. Furthermore, I will discuss how beneficial exosomal communication could be enhanced for therapeutic purposes.