Novel Stromal Biomarker Could Triple Eligibility for Immunotherapy in Patients with Colorectal Cancer

Spanish researchers identify CTHRC1 protein as a key biomarker for predicting immunotherapy success and treatment resistance in colon and rectal cancer.

By: AXL Media

Published: Apr 14, 2026, 11:47 AM EDT

Source: Information for this report was sourced from EurekAlert!

Targeting the Tumor Ecosystem

While most cancer research focuses on the genetic mutations within tumor cells, a new study led by the Hospital del Mar Research Institute (HMRIB) and IRB Barcelona shifts the focus to the "neighborhood" surrounding the cancer. Researchers have identified a specific population of cancer-associated fibroblasts (CAFs) that express the protein CTHRC1. These connective tissue cells are not cancerous themselves, but they act as essential support systems for tumor proliferation and treatment resistance. By monitoring these CTHRC1(+) CAFs, clinicians can now gain a clearer picture of a tumor’s likely behavior and its susceptibility to the patient's immune system.

Expanding the Scope of Immunotherapy

Currently, immunotherapy is a viable option for only about 5% of colorectal cancer patients—primarily those with specific genetic markers. However, the discovery of CTHRC1(+) CAFs as a biomarker may change this paradigm. The study indicates that the presence of these cells allows pathologists to determine the state of immune cells within the tumor and their actual ability to attack neoplastic cells. This finding suggests that many patients previously excluded from immunotherapy based on traditional genetic criteria may actually be strong candidates for the treatment, potentially expanding the pool of eligible patients.

A Reliable Predictor of Treatment Resistance

The research team conducted a massive validation process, analyzing samples from nearly 3,000 patients across 17 different cohorts. The results consistently showed that high levels of CTHRC1 protein are linked to the activity of TGF-beta, a cytokine associated with poor disease outcomes and resistance to standard treatments. By identifying this protein early, doctors can pinpoint patients who are unlikely to respond to conventional chemotherapy and instead move them toward targeted inhibitors or novel immune-based strategies, saving critical time in the treatment cycle.