The implementation of liquid biopsies in routine care of patients with advanced solid cancer (LIQPLAT): a study protocol for a single arm trial

O_LIBackground: Advanced solid cancers present significant treatment challenges due to their genomic heterogeneity and resistance. Liquid biopsies, specifically circulating tumour DNA (ctDNA), have emerged as promising tools to support treatment decision making. However, evidence regarding their implementation in routine care remains limited. C_LIO_LIMethods: LIQPLAT is a single-arm trial (SAT), assessing the feasibility of implementing ctDNA measurements in the usual care of patients with advanced solid cancers excepting primary brain tumours, at the University Hospital Basel. Patients are randomly invited from an ongoing research registry to take part in the SAT. We aim to include 150 randomly invited patients to receive ctDNA measurements alongside standard care. CtDNA samples are collected at baseline, between the second and third months, fifth and seventh months after cancer treatment start, and during serious clinical events such as disease progression or treatment changes. Results are evaluated by a molecular tumor board to guide clinical management. Feasibility outcomes include detectability of ctDNA, identification of actionable alterations, and analysis turnaround time. Other outcomes include patient-reported quality of life, progression-free survival and overall survival, time to next treatment line, and unscheduled hospital and emergency visits, all obtained from routine healthcare data. C_LIO_LIDiscussion: LIQPLAT will examine the implementation of ctDNA measurements in routine care. The random selection for invitation to this SAT within an existing registry embedded in routine care creates a representative sample and allows for better assessment of implementation and generalization of findings. C_LIO_LITrial registration: The trial is registered at clinicaltrials.gov (2024-04-11, NCT06367751) and kofam.ch (2024-03-15, SNCTP000005844). C_LI