# A compass in the challenge: the CALLY index as a prognostic biomarker in advanced cholangiocarcinoma treated with chemoimmunotherapy: a retrospective propensity score-matched cohort study

## TL;DR

The CALLY index is a new biomarker that helps predict survival and quality of life in advanced cholangiocarcinoma patients receiving chemoimmunotherapy.

## Contribution

The study introduces the CALLY index as a novel prognostic tool for advanced cholangiocarcinoma patients undergoing chemoimmunotherapy.

## Key findings

- High CALLY index correlates with significantly longer overall and progression-free survival in matched patient groups.
- The CALLY index is a validated prognostic factor with good model performance for survival prediction.
- Patients with a high CALLY index experience slower deterioration in quality of life over time.

## Abstract

The management of advanced cholangiocarcinoma (CCA) remains a clinical challenge. Prognostic biomarkers are needed to guide treatment decisions. The C-reactive protein–albumin–lymphocyte (CALLY) index reflects nutritional, immune, and inflammatory status and has shown prognostic value in other cancers. However, its role in CCA patients receiving chemoimmunotherapy is unexplored.

We conducted a retrospective propensity score-matched (PSM) cohort study involving advanced CCA patients who were treated with chemoimmunotherapy. Participants were stratified into high- or low-CALLY groups based on an optimal cut-off value of 1.42. PSM (1:1) was applied to balance baseline covariates. Overall survival (OS) and progression-free survival (PFS) were compared between groups using Kaplan-Meier analysis, and Cox regression analysis was employed to identify prognostic factors. The prognostic models underwent comprehensive internal validation, including bootstrap resampling (1,000 iterations) for calibration and discrimination assessment. Health-related quality of life (HRQoL) was assessed using a mixed model for repeated measures.

After 1:1 propensity matching, 55 patients were retained in each group, with balanced baseline characteristics. The high-CALLY group exhibited significantly longer median OS (13.00 months vs. 11.50 months; P = 0.019) and PFS (7.50 months vs. 6.00 months; P = 0.020). Cox analysis confirmed the CALLY index as a valuable prognostic factor for both OS (hazard ratio (HR), 0.68; 95% confidence interval (CI), 0.50 to 0.93; P = 0.014) and PFS (HR, 0.70; 95% CI, 0.58 to 0.85; P < 0.001). Internal validation demonstrated good model performance, with optimism-corrected C-indices of 0.704 for OS and 0.716 for PFS. Furthermore, patients with a high CALLY index showed significantly slower deterioration in HRQoL from week 18 onward (P < 0.05).

The CALLY index is a robust prognostic biomarker for advanced CCA patients undergoing chemoimmunotherapy, associated with significantly improved survival and better-preserved quality of life. Its integration into clinical practice could enhance risk stratification and facilitate personalized treatment strategies.