Clinical bottom line
Circulating tumor DNA (ctDNA) analysis in metastatic renal cell carcinoma (mRCC) is an emerging biomarker approach with potential to guide treatment adaptation by monitoring tumor dynamics noninvasively. Early evidence suggests that ctDNA detection and clearance correlate with tumor burden and treatment response, offering a putative tool to personalize systemic therapy selection and timing. However, ctDNA-guided treatment adaptation in mRCC remains investigational, with limited prospective validation and technical challenges in reliably detecting tumor-informed ctDNA. Clinicians should consider ctDNA data as hypothesis-generating and complementary to established clinical and radiographic assessments until further evidence clarifies its clinical utility.
What the evidence shows
Renal cell carcinoma (RCC) is a heterogeneous malignancy often diagnosed at advanced stages where systemic therapy is the mainstay (Erdem et al., 2015). The advent of targeted therapies and immune checkpoint inhibitors has improved outcomes but also introduced complexity in treatment sequencing and monitoring (Thean et al., 2013; Michalaki et al., 2013). Traditional imaging and serum markers have limitations in early detection of treatment resistance or progression.
Cell-free ctDNA, shed by tumor cells into the bloodstream, offers a minimally invasive biomarker to capture tumor genetic alterations and dynamics in real time. Hahn et al. (2019) reviewed the current knowledge of ctDNA in mRCC, highlighting that ctDNA can reflect tumor burden and molecular heterogeneity. Detection rates vary depending on tumor characteristics and assay sensitivity, with higher ctDNA levels associated with metastatic disease and aggressive histology.
Recent data from a single-center experience by Ayanambakkam et al. (2025) demonstrated that ctDNA clearance during systemic therapy correlated with improved prognosis in both localized and metastatic RCC. This suggests ctDNA dynamics could serve as an early biomarker of treatment efficacy, potentially guiding adaptive therapy decisions such as switching agents or intensifying treatment.
An erratum-corrected study in JCO Precision Oncology (2024) identified tumor characteristics linked to preoperatively detectable tumor-informed ctDNA in renal masses suspicious for RCC. This underscores the importance of tumor-informed assays that track patient-specific mutations to improve ctDNA detection accuracy, a critical factor for clinical application.
Caveats and uncertainty
Despite promising findings, ctDNA-guided treatment adaptation in mRCC is not yet standard of care. Detection sensitivity remains a challenge due to low ctDNA shedding in some RCC subtypes and the complex tumor microenvironment (Hahn et al., 2019). The heterogeneity of RCC and its metastatic sites may limit the representativeness of ctDNA profiles.
Most evidence derives from small cohorts or retrospective analyses, with a paucity of prospective trials validating ctDNA-guided treatment changes. The optimal timing, frequency, and thresholds for ctDNA monitoring are undefined. Additionally, standardization of ctDNA assays and integration with clinical parameters require further development.
The clinical impact of ctDNA-guided adaptation on survival, quality of life, and cost-effectiveness remains unknown. There is also a need to clarify how ctDNA findings should influence decisions among available targeted therapies and immunotherapies, given their differing mechanisms and resistance patterns.
How this may change practice
If validated, ctDNA-guided treatment adaptation could transform mRCC management by enabling earlier detection of resistance and personalized therapy adjustments, potentially improving outcomes and sparing unnecessary toxicity. Clinicians may incorporate serial ctDNA monitoring alongside imaging to refine response assessment and guide sequencing of targeted agents or immunotherapies.
In the near term, ctDNA analysis may serve as a valuable research tool to stratify patients in clinical trials and explore mechanisms of resistance. Multidisciplinary collaboration and prospective studies are essential to establish standardized protocols and demonstrate clinical benefit.
Until robust evidence emerges, ctDNA results should be interpreted cautiously and integrated with established clinical and radiologic data rather than used in isolation for treatment decisions.