Nature Medicine Study Shows Resero Bio's Cell-Free RNA Platform Detects Bladder Cancer and Predicts Treatment Response

New research shows that a non-invasive urine sample can reveal not just whether a tumor is present, but how it will respond to treatment, expanding what cell-free RNA diagnostics can do beyond detection alone.

SAN CARLOS, Calif., Oct. 5, 2026 /PRNewswire/ -- Resero Bio, a precision diagnostics company building a cell-free RNA (cfRNA) liquid biopsy platform, today announced publication of a Stanford-led study in Nature Medicine demonstrating that analysis of urine cfRNA can detect bladder cancer non-invasively and identify molecular residual disease (MRD). It also showed the ability to distinguish tumor aggressiveness and predict which patients will respond to immunotherapy versus chemotherapy. The publication marks a key milestone for Resero Bio, providing clinical validation for the RARE-seq platform the company is building out across both urine and plasma, and across multiple cancer types.

"This study presents the clearest evidence yet that cell-free RNA carries far more clinically relevant information than a binary detection call," said Monica Nesselbush, PhD, CEO and Co-founder of Resero Bio. "We're not just asking whether cancer is present. We're reading out gene expression programs associated with tumor grade, stage, immune biology, and treatment response, all from a urine sample. Moving beyond detection to deeper characterization is the foundation of our platform, and bladder cancer represents a prime example of how that capability can deliver value throughout the patient journey."

Researchers from Stanford Cancer Institute, the VA Palo Alto Health Care System, and collaborating institutions analyzed 683 urine samples from bladder cancer patients and controls using uRARE-seq, a proprietary targeted cfRNA sequencing method for urine samples built on Resero Bio's core RARE-seq technology. Building on previously presented work showing that urine cfRNA analysis enables detection of localized bladder cancer with high sensitivity and specificity, the new publication reports findings that move the platform beyond detection and into the realm of tumor biology. Highlights of the study are provided below.

 The cfRNA liquid biopsy platform enabled:

• Highly sensitive detection of bladder cancer from pre-treatment urine along with discrimination of low-grade from high-grade bladder tumors and non-muscle invasive from muscle-invasive disease — two determinations that currently require tissue sampling via biopsy or resection.
  
  
• Identification of a pre-treatment molecular signature of immunotherapy response. Patients who achieved a complete molecular response to BCG immunotherapy showed pre-existing anti-tumor immune response signatures in urine cfRNA before treatment even began.
  
  
• Identification of MRD after treatment, distinguishing patients with complete molecular responses to surgery from those with incomplete responses to surgery who then responded to adjuvant BCG. Patients with complete molecular responses to either surgery or BCG showed much lower risk for recurrence than those with detectable tumor cfRNA after treatment.
  
  
• Detection of transcriptionally distinct cfRNA profiles in urine samples from patients with renal cell carcinoma and prostate adenocarcinoma, providing preliminary evidence that urine cfRNA can be used for kidney and prostate cancer applications as well.

"Bladder cancer management is full of moments where a clinician has to make a consequential decision with incomplete information: How aggressive is this tumor? Will it respond to BCG? Is there residual disease after treatment?" said Max Diehn, MD, PhD, Co-founder and Scientific Advisor of Resero Bio. "Liquid biopsies have mostly been used to detect the presence of cancer. This work shows they can also help inform treatment strategy, which is ultimately what matters most to providers and their patients."

Ash Alizadeh, MD, PhD, Co-founder and Scientific Advisor of Resero Bio, said, "What's compelling about this dataset is that the biology holds up across independent training and validation cohorts, and the predictive signal for BCG response was there before treatment even started. That kind of pre-treatment stratification is exactly what's needed to make smarter, faster decisions in the clinic and in the drug development pipelines built around these patients."

While this publication centers on bladder cancer and urine, the RARE-seq platform is disease- and biofluid-agnostic by design. With capture panels optimized for both urine and plasma, proof-of-concept cfRNA signal has been generated at Resero Bio and Stanford across ten solid tumor types to date. Resero Bio's platform is available now for research use.

About Resero Bio

Resero Bio is a precision diagnostics company unlocking the full potential of precision medicine by measuring the cell-free transcriptome. Its proprietary liquid biopsy platform, RARE-seq, is purpose built for cell-free RNA sequencing with an AI/ML-enabled bioinformatics engine to deliver biologically meaningful, clinically actionable insights from plasma or urine — without requiring tissue or prior tumor sequencing. The platform supports non-invasive cancer detection, molecular and histological subtyping, risk stratification, treatment response prediction, pharmacodynamic monitoring, toxicity assessment, and characterization of resistance mechanisms across cancer types. Founded by researchers from Stanford Medicine, Resero Bio is based in San Carlos, California, and is exclusively licensed to develop the RARE-seq platform for commercial use. For more information, visit reserobio.com.

Media Contact
Monica Nesselbush
[email protected]

SOURCE Resero Bio