Abstract 115P
Background
Next-generation sequencing (NGS) enables comprehensive genomic profiling of tumors, providing insights into actionable mutations, resistance mechanisms, and tumor heterogeneity. However, tissue biopsies are often unfeasible in advanced or metastatic cancers due to insufficient or inaccessible tumor tissue. Liquid biopsy, analyzing circulating tumor DNA (ctDNA) from blood samples, offers real-time molecular insights, especially when tissue samples are unavailable.
Methods
Liquid biopsies were performed using the Guardant360CDx® test on patients with advanced solid tumors at Hospital Clínico San Carlos over one year. The test analyzes ctDNA to detect clinically relevant alterations, such as single nucleotide variants, indels, fusions, and amplifications. Patients with insufficient tissue for conventional biopsy were selected, and data were analyzed to identify actionable mutations.
Results
A total of 72 liquid biopsies identified 228 genomic alterations: mutations (91%), amplifications (5%), indels (2%), and fusions (2%). The most frequently altered genes were TP53 (19%), KRAS (10%), and PIK3CA (8%). Actionable alterations were detected in 35% of patients, enabling targeted therapies or clinical trial inclusion. The most common actionable alterations were found in EGFR, PIK3CA, ERBB2, ESR1, MET, and fusions involving ROS1 or ALK. One MSI-H case was also detected. Four patients had no detectable ctDNA, likely due to low tumor burden or isolated brain metastases. Five germline alterations led to diagnoses of hereditary cancer syndromes. An incidental JAK2 mutation enabled the diagnosis of an underlying myelodysplastic syndrome.
Conclusions
Liquid biopsy proved clinically useful in genomic profiling of advanced solid tumors, particularly when tissue biopsies were unfeasible. It enabled targeted therapies and clinical trial participation for many patients. The ability to detect actionable alterations underscores the role of liquid biopsy in personalizing cancer treatment and broadening therapeutic options.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.