Learning from BISCAY: The future of biomarker-based trial design in bladder cancer

Circulating tumor DNA based minimal residual disease detection and adjuvant treatment decision-making for muscle-invasive bladder cancer guided by modern clinical trials

Up to 430,000 cases of bladder cancer are diagnosed each year worldwide. A proposed method for non-invasive monitoring has been to utilize a "liquid biopsy." Liquid biopsy has been proposed as a non-invasive method of testing biomarkers in bodily fluids in order to detect and survey cancer. The liquid biopsy could be utilized to obtain information regarding circulating tumor cells, circulating cell-free tumor DNA, circulating cell-free tumor RNA, and more. It is currently being investigated to help guide adjuvant therapy and improve oncological outcomes. We highlight an array of exciting past and ongoing clinical trials regarding ctDNA and adjuvant therapy in regard to urothelial carcinoma which we believe to be amongst the leaders in the field.

Challenges and the Evolving Landscape of Assessing Blood-Based PD-L1 Expression as a Biomarker for Anti-PD-(L)1 Immunotherapy

While promising, PD-L1 expression on tumor tissues as assessed by immunohistochemistry has been shown to be an imperfect biomarker that only applies to a limited number of cancers, whereas many patients with PD-L1-negative tumors still respond to anti-PD-(L)1 immunotherapy. Recent studies using patient blood samples to assess immunotherapeutic responsiveness suggests a promising approach to the identification of novel and/or improved biomarkers for anti-PD-(L)1 immunotherapy. In this review, we discuss the advances in our evolving understanding of the regulation and function of PD-L1 expression, which is the foundation for developing blood-based PD-L1 as a biomarker for anti-PD-(L)1 immunotherapy. We further discuss current knowledge and clinical study results for biomarker identification using PD-L1 expression on tumor and immune cells, exosomes, and soluble forms of PD-L1 in the peripheral blood. Finally, we discuss key challenges for the successful development of the potential use of blood-based PD-L1 as a biomarker for anti-PD-(L)1 immunotherapy.