IMAGING-DETECTED immune-related adverse events (irAEs) may serve as an early indicator of improved survival in patients with advanced biliary tract cancer (BTC) treated with durvalumab-based chemotherapy, according to new research.
The findings suggest that radiologically identified irAEs, many of which occur without symptoms, could help clinicians identify patients more likely to experience favourable treatment outcomes.
BTCs are a group of aggressive malignancies that includes intrahepatic and extrahepatic cholangiocarcinoma and gallbladder cancer. Five-year survival rates remain low, and while surgical resection offers the only potentially curative option, most patients present with advanced disease that is unsuitable for surgery. Therefore, systemic chemotherapy remains the standard treatment approach for many patients.
Immunotherapy Expands Treatment Options in BTC
Immune checkpoint inhibitors have become an important addition to BTC treatment in recent years. Durvalumab, an anti-PD-L1 monoclonal antibody, was shown to improve overall survival when combined with gemcitabine and cisplatin in the TOPAZ-1 trial. Similarly, pembrolizumab demonstrated a survival benefit alongside first-line chemotherapy in the KEYNOTE-966 trial.
These advances have led to the incorporation of durvalumab- or pembrolizumab-based combinations into recommended treatment regimens for advanced BTC. However, immunotherapy introduces a distinct spectrum of toxicities known as immune-related adverse events.
Silent Radiological Findings Carry Prognostic Value
Researchers found that imaging-detected irAEs frequently emerged early during treatment, with 85.7% of cases occurring within 90 days of therapy initiation. Notably, only 35.7% of patients with imaging-detected irAEs experienced related clinical symptoms.
Despite often going unnoticed clinically, the presence of imaging-detected irAEs was linked to significantly better outcomes. In multivariate analysis, these radiological findings independently predicted improved overall survival (HR=0.42; p=0.017) and progression-free survival (HR=0.43; p=0.016).
Median overall survival reached 23.0 months among patients with imaging-detected irAEs, compared with 12.0 months for those without such findings, a statistically significant difference (p=0.009).
Implications for Radiological Monitoring
Immune-related adverse events can affect multiple organ systems and are thought to result from immune system overstimulation triggered by checkpoint inhibition. CT and MRI play a central role in identifying and characterising these complications.
The findings indicate that routine imaging surveillance may provide information beyond disease assessment alone. Because imaging-detected irAEs often appear before symptoms develop and were linked to longer survival, careful radiological monitoring could help identify patients who are deriving greater benefit from durvalumab-based treatment.
While the study demonstrates a strong prognostic relationship, the results do not establish that irAEs directly improve survival. Instead, imaging-detected irAEs may reflect a more active immune response to checkpoint inhibition, serving as an early marker of patients whose tumours are responding more effectively to treatment. This suggests that radiological evidence of immune activation may provide clinicians with additional insight into treatment response, even when patients remain asymptomatic.
Reference
Yoo J et al. Prognostic value of imaging-detected immune-related adverse events in biliary tract cancer patients receiving durvalumab-based chemotherapy. Eur Radiol. 2026;DOI:10.1007/s00330-026-12645-x.
Featured image: st.kolesnikov on Adobe Stock
