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Updated: Aug 11, 2025
Intramucosal Inoculation of Squamous Cell Carcinoma Cells in Mice for Tumor Immune Profiling and Treatment Response Assessment
Published on: April 22, 2019
Extensive molecular profiling of squamous cell anal carcinoma in a phase 2 trial population: Translational analyses
Alessandra A Prete1, Paolo Manca2, Marco Messina3
1Medical Oncology 1, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy.
Background:
Molecular characteristics of squamous cell anal carcinoma (SCAC) are poorly explored. Immune checkpoint inhibitors showed limited activity in phase I/II trials, but predictive and prognostic biomarkers are lacking.
Patients And Methods:
In the phase II randomised trial CARACAS (NCT03944252), avelumab alone (Arm A) or with cetuximab (Arm B) was tested in pre-treated advanced SCAC , with overall response rate being the primary end-point. On pre-treatment tumour tissue samples, we assessed Human papillomavirus status, programmed-death ligand 1 (PD-L1) expression, mismatch repair proteins expression, tumour mutational burden (TMB) and comprehensive genomic profiling by FoundationOne CDx. Tumour-infiltrating lymphocytes were characterised on haematoxylin-eosine-stained samples. Primary objective was to describe response to immunotherapy in the CARACAS trial population according to molecular and histological characteristics. Secondary objectives were to assess progression-free survival (PFS) and overall survival (OS) according to molecular biomarkers.
Results:
High PD-L1 (>40 with combined positive score) was significantly more frequent in patients with disease control (p = 0.0109). High TMB (>10 mutations per megabase) was related to better OS (hazard ratio (HR) = 0.09; 95%confidence interval (CI) 0.01-0.68; p = 0.019) and PFS (HR = 0.44; 95%CI = 0.15-1.27; p = 0.129). High expression of PD-L1 conferred longer OS (HR = 0.46; 95%CI = 0.19-1.08; p = 0.075) and PFS (HR = 0.42; 95%CI = 0.20-0.92; p = 0.03). Neither OS (HR = 1.30; 95%CI = 0.72-2.36; p = 0.39) or PFS (HR = 1.31; 95%CI = 0.74-2.31; p = 0.357) was affected by high (>1.2) Tumour-infiltrating lymphocytes count. High TMB and PD-L1identified patients were with significantly better OS (HR = 0.33; 95%CI = 0.13-0.81; p = 0.015) and PFS (HR = 0.48; 95%CI = 0.23-1.00; p = 0.015).
Conclusions:
To our knowledge, TranslaCARACAS is the first study to document prognostic role of TMB and PD-L1 in advanced SCAC patients treated with immune checkpoint inhibitors.
Insights
This study found that high programmed-death ligand 1 (PD-L1) expression and high tumour mutational burden (TMB) are associated with better outcomes in advanced squamous cell anal carcinoma (SCAC) patients treated with immune checkpoint inhibitors.
Area of Science:
- Oncology
- Immunotherapy
- Molecular Diagnostics
Background:
- Squamous cell anal carcinoma (SCAC) molecular characteristics are under-researched.
- Predictive and prognostic biomarkers for immune checkpoint inhibitor (ICI) therapy in SCAC are lacking, despite limited efficacy in early trials.
Purpose of the Study:
- To investigate the prognostic role of molecular and histological features in advanced SCAC patients receiving immunotherapy.
- To assess the impact of programmed-death ligand 1 (PD-L1) expression and tumour mutational burden (TMB) on treatment outcomes in the CARACAS trial.
Main Methods:
- The CARACAS trial (NCT03944252) evaluated avelumab with or without cetuximab in pre-treated advanced SCAC.
- Pre-treatment tumor samples were analyzed for Human papillomavirus status, PD-L1 expression, mismatch repair proteins, TMB, and comprehensive genomic profiling.
- Tumor-infiltrating lymphocytes (TILs) were assessed on H&E-stained samples.
Main Results:
- High PD-L1 expression (>40 CPS) correlated with disease control (p=0.0109).
- High TMB (>10 mutations/Mb) was linked to improved overall survival (OS) (HR=0.09, p=0.019) and progression-free survival (PFS) (HR=0.44, p=0.129).
- High PD-L1 expression was associated with longer OS (HR=0.46, p=0.075) and PFS (HR=0.42, p=0.03). Combined high TMB and PD-L1 predicted significantly better OS (HR=0.33, p=0.015) and PFS (HR=0.48, p=0.015). TILs did not significantly impact OS or PFS.
Conclusions:
- This study is the first to demonstrate the prognostic value of TMB and PD-L1 in advanced SCAC patients treated with ICIs.
- TMB and PD-L1 expression are potential biomarkers for predicting treatment response and survival in SCAC immunotherapy.
