Implementation of Liquid Biopsies During Routine Clinical Care in Patients With Advanced Malignancies (LIQPLAT)

The goal of this study is to assess the implementation and feasibility of ctDNA measurements from blood samples obtained during routine clinical care of cancer patients in the University Hospital Basel. Researchers will compare clinical and patient reported outcomes from the LIQPLAT study with patients who did not receive ctDNA measurements (external comparator from registry AO\_2023-00091). Blood samples will be drawn from the patients as part of routine care and ctDNA measurements will be performed on these samples.

Liquid biopsies, in particular the analysis of circulating tumor DNA (ctDNA), have emerged as a promising tool for detecting and monitoring cancer. Measuring ctDNA in patients with solid malignancies may help to identify targetable alterations, measure disease burden, identify early mutations of resistance, tailor and deescalate cancer treatment, and predict patient prognosis. Although the adoption and application of ctDNA measurements for patients with solid tumors in routine clinical care is increasing, evidence supporting the integration of ctDNA into current practice is limited, especially for patients with advanced cancers. This is a trial using routinely collected health care data from an ongoing registry (AO\_2023-00091) in cancer patients with advanced solid malignancies receiving first line systemic anticancer treatment for advanced disease. This trial will assess the feasibility and implementation of routine measurement of ctDNA and its association with clinical outcomes, including quality of life and survival. All patients will receive routine diagnostics, treatment and follow-up. All patients with a new cancer diagnosis will be assessed for eligibility based on the routinely collected information available in the registry. We will then randomly decide which eligible patients are invited to participate in the trial. If patients accept the invitation and intend to get a measurement of ctDNA, they have to provide written informed consent. Results from ctDNA analyses will be discussed at the molecular tumor board, an established regular interdisciplinary meeting at the University Hospital Basel (part of routine care) to discuss patients with complex findings from tumor sequencing analyses. Treatment changes occurring during the trial duration will be at the discretion of treating physician and according to patient's preference as is routine standard of care.