Implementation of a novel immune monitoring strategy for multicenter clinical trials to enable equity in cancer prognosis for individuals from remote settings of Australia

Improved cancer prognosis begins with the collection of high-quality data from clinical trials. However, execution of longitudinal immune phenotyping studies by flow cytometry is complex due to logistical challenges that could affect data quality. The challenges of immune monitoring are exacerbated when considering remote and rural communities in Australia, which are burdened by both an increased prevalence and worse prognosis of cancer. Paradoxically, these communities are often underrepresented in clinical trials. Our group has developed a novel blood-based “immune signature” that robustly predicts failure to make a clinical response to checkpoint therapies targeting the PD-1/PD-L1 pathway in melanoma and lung cancer. We have now taken these groundbreaking findings to implement in remote clinical settings, along with an expanded CyTOF™ panel for 50-plus-parameter analysis of cancer patient peripheral blood samples. Recent developments in CyTOF technology facilitate a highly simplified workflow of asynchronous sample collection and staining, compatible with current hospital laboratories, which typically run on unpredictable schedules, to remote settings, which are resource-poor and have limited clinical trial infrastructure. This is uniquely enabled by using a stable, dried-down cocktail of CyTOF antibodies and an easy-to-follow protocol that yields reproducible staining while minimizing sample required. Furthermore, this unique mass cytometry workflow provides flexibility and minimizes technical variation via sample barcoding and freezing of stained samples for shipment to a central site for batch acquisition. As such, this study is designed to demonstrate both clinical impact of the large panel and utility of CyTOF technology for a highly simplified and robust workflow for multi-site clinical trials. Here we present findings from the implementation of this novel workflow through a 100-sample pilot study at three sites across Australia, in a variety of clinical implementation setups. Remote asynchronous sample collection was performed to compare two surface staining approaches on i) PBMC versus ii) plasma-depleted whole blood to suit settings where centrifugation access was readily available or not, respectively. Stained samples were shipped to a central lab for processing. In the case of cryopreserved whole blood, bead-based granulocyte depletion was first performed, with all samples subsequently multiplex barcoded together for intracellular antibody staining of key functional markers. Analysis harmonization was achieved across sample collection sites and staining approaches. Overall, this workflow enables access to underserved communities, facilitating for the first time equity and scalability of immune phenotyping studies to harness truly geographically dispersed clinical centers.