Chad Tang, MD, on KIM-1 and ctDNA in oligometastatic ccRCC

In the following interview, conducted at the 2026 ASCO Genitourinary Cancers Symposium in San Francisco, California, Chad Tang, MD, discusses the development of a prognostic model—K-COMPASS—for patients with oligometastatic clear cell renal cell carcinoma (ccRCC). Tang is an associate professor of radiation oncology at the University of Texas MD Anderson Cancer Center in Houston, Texas.

Tang began by explaining the rationale for the study, which stemmed from prior evidence showing that the 2 blood-based biomarkers—kidney injury molecule-1 (KIM-1) and circulating tumor DNA (ctDNA)—are each independently prognostic in kidney cancer. However, it remained unclear whether combining these biomarkers would enhance prognostic accuracy.

To address this question, investigators analyzed a single-arm, phase 2 cohort of patients with oligometastatic ccRCC receiving radiation therapy, evaluating KIM-1 and ctDNA levels at baseline and at 3 months, and integrating these biomarkers with demographic and disease-related clinical factors to develop a composite prognostic model. In total, the study included 112 patients who were enrolled on a single-arm phase 2 trial of metastasis-directed therapy without systemic therapy (NCT03575611).

Regarding key findings, both KIM-1 and ctDNA were associated with systemic therapy–free survival at baseline and at the 3-month follow-up time point. KIM-1 was also associated with progression-free survival and overall survival at baseline (PFS: HR, 2.2; 95% CI, 1.5 to 3.3; OS: HR, 5.1; 95% CI, 2.5 to 10.2) and 3 months (PFS: HR, 3.5; 95% CI, 2.2 to 5.5; OS: HR, 5.0; 95% CI, 2.3 to 10.9) (all P < .001).

Importantly, when KIM-1 and ctDNA were combined with 4 clinical factors (prior systemic therapy lines, ECOG performance status, number of metastatic lesions, time from diagnosis to metastasis) into a unified prognostic model, the investigators observed strong discriminatory ability (C-index=0.76). The integrated model was able to more accurately stratify patients according to their likelihood of remaining off systemic therapy vs those who may require earlier treatment initiation.

According to Tang, this approach may help identify patients who can safely defer systemic therapy following radiation therapy alone and those who may benefit from closer monitoring or earlier therapeutic intervention, underscoring the potential clinical utility of incorporating blood-based biomarkers into risk stratification for oligometastatic ccRCC.

REFERENCE
1. Tang C. Circulating KIM-1 and ctDNA as prognostic markers in oligometastatic clear cell renal cell carcinoma (ccRCC): The K-COMPASS model. Presented at: 2026 American Society of Clinical Oncology Genitourinary Cancers Symposium. February 26-28, 2026. San Francisco, California. Abstract 537. https://www.asco.org/abstracts-presentations/257445/abstract