In recent years, tremendous advances have been made in the treatment of some types of cancer using strategies which engage or exploit components of the immune system. For example, monoclonal antibodies (mAbs) directed toward molecules expressed by cancer cells but not healthy cells can be used in targeted therapy approaches, whereas checkpoint blockade immunotherapy (CBI) relies on blocking the function of negative immune regulatory molecules to stimulate endogenous anti-cancer T cell responses. While these therapeutic advances are exciting, they help only a fraction of cancer patients. In particular, mAb-based targeted therapies are only available for select cancers where a good target antigen on cancer cells has been identified, and CBI is only effective for certain cancer types which already engage the immune system. Even within those CBI-responsive cancers, only a fraction of patients respond favourably to therapy. Accordingly, there is intense interest in better understanding, and broadening the utility of, these approaches.
I will describe two new studies where our team has used flow cytometry to begin addressing these objectives. In the first, we have performed a detailed expression study of fibroblast activation protein (FAP) in glioblastoma brain tumours. Single cell suspensions were generated from patient tumour specimens and expression patterns of FAP assessed on the diverse cell types within tumours. The expression patterns detected support the development of therapies based on immune targeting of FAP for the treatment of glioblastoma. In the second study, we have collected blood samples from melanoma patients before and after receiving CBI and analysed in detail the changes occurring to T cells in response to treatment. By correlating these changes to clinical outcome, we aim to better understand the mechanism of action of CBI, identify biomarkers to predict which patients will respond, and discover ways to increase treatment efficacy.