Editor's Note: At a recent academic session, Professor Taigo Kato from the Osaka University Graduate School of Medicine presented the preliminary results of the MONSTAR-SCREEN-3 study. The study investigates the clinical utility of an ultra-sensitive whole-genome sequencing (WGS)-based circulating tumor DNA (ctDNA) assay for the detection of molecular residual disease (MRD) in patients with resectable renal cell carcinoma (RCC).01 Current Challenges: Addressing the “Low-Shedding” Nature of RCC
While ctDNA has become a validated biomarker for MRD detection and recurrence risk stratification in various solid tumors (e.g., colorectal cancer), renal cell carcinoma (RCC) has traditionally been categorized as a “low-shedding” tumor. Due to the minimal release of tumor DNA into the bloodstream, conventional assays often lack the sensitivity required for reliable clinical monitoring. The MONSTAR-SCREEN-3 study utilizes an ultra-sensitive detection platform to determine the feasibility of precise MRD monitoring in the RCC setting.
02 Technical Methodology: Tumor-Informed Personalized WGS Platform
The study employed a tumor-informed WGS approach to generate personalized detection panels for each patient.
- Variant Coverage: Each panel incorporates up to 1,000 tumor-specific variants.
- Genomic Enrichment: Data indicated that 99% of the detected variants were located in non-coding regions. Compared to assays targeting only coding regions, this WGS-based panel demonstrated an approximately 100-fold enrichment in variant detection.
- Sampling Intervals: Blood samples were collected at baseline (pre-surgery), one month post-surgery, and every three months during the first postoperative year.
03 Core Data: 100% Baseline Detection and MRD Dynamics
The preliminary cohort of MONSTAR-SCREEN-3 included 29 patients with resectable RCC (primarily pathological T3 stage; 6.9% with lymph node metastasis).
- Baseline Sensitivity: The assay achieved a 100% baseline detection rate, with 44.8% of samples falling within the ultra-sensitive range.
- Postoperative MRD Status: At one month post-surgery, the MRD positivity rate was 11.1%. Notably, 50% of these positive cases were detected specifically at the ultra-sensitive level.
- Early-Stage Detection: In patients with Stage I/clinical T1 disease, the assay maintained a ctDNA detection rate of 67% at the ultra-sensitive level.
- Correlation Analysis: Plasma tumor fraction (TF) was significantly associated with tumor stage, tumor size, and nodal status.
04 Clinical Significance: Correlation Between ctDNA Status and Recurrence
The study analyzed the longitudinal correlation between postoperative ctDNA dynamics and clinical outcomes:
- MRD-Negative Group: Twenty-five patients who cleared ctDNA post-surgery and remained MRD-negative showed no signs of recurrence during follow-up.
- MRD-Positive Group: Patients with persistent postoperative ctDNA positivity all experienced clinical recurrence.
- Case Study: The presentation highlighted a patient with T3aN1M0 RCC who underwent radical surgery followed by adjuvant pembrolizumab. Despite immunotherapy, ctDNA remained persistently positive. Clinical recurrence (lung metastasis) was confirmed via imaging at 6 months post-surgery, demonstrating that ultra-sensitive ctDNA detection can identify relapse significantly earlier than standard radiographic assessments.
05 Conclusion and Outlook
Professor Taigo Kato concluded that the MONSTAR-SCREEN-3 study demonstrates the robust capability of WGS-based personalized assays to detect ctDNA in RCC, effectively overcoming the limitations of “low-shedding” tumors. The high baseline sensitivity and the strong correlation between persistent MRD and clinical relapse suggest that this technology could play a pivotal role in postoperative management and adjuvant therapy decision-making. The research team intends to expand the cohort and provide updated data with longer follow-up at future meetings.
