# Circulating Hsp70: a tumor biomarker for lymph node metastases and early relapse in thoracic cancer

## TL;DR

The study shows that high levels of circulating Hsp70 in the blood can predict lymph node metastases and early relapse in thoracic cancer patients.

## Contribution

This study introduces circulating extracellular Hsp70 (eHsp70) as a novel predictive biomarker for lymph node metastases and early relapse in thoracic cancer.

## Key findings

- Circulating eHsp70 levels were significantly higher in non-small cell lung cancer patients compared to healthy individuals.
- Higher eHsp70 levels correlated with lymph node metastases and early relapse in thoracic cancer patients.
- eHsp70 levels were associated with PD-L1 status and increased with disease progression from early to metastatic stages.

## Abstract

Heat shock protein 70 (Hsp70) which is frequently overexpressed in many different cancer types is also present on the plasma membrane of tumor but not normal cells. The intensity of membrane-expressed Hsp70 (mHsp70) is associated with disease progression and treatment resistance. It has also been shown that Hsp70 can be actively released into the circulation by mHsp70 positive, viable tumor cells in the form of extracellular lipid microvesicles expressing mHsp70, the levels of which might therefore act as a potential biomarker for tumor aggressiveness in lung malignancies.

Extracellular Hsp70 (eHsp70) was measured in the plasma of patients with non-small cell lung cancer (n = 178, NSCLC) and lung metastases of extrathoracic tumors (n = 35) prior to surgery using the Hsp70-exo ELISA which detects microvesicle-associated eHsp70 and the patient`s immunophenotype was determined by flow cytometric analysis of the corresponding peripheral blood lymphocytes.

eHsp70 values were significantly higher in patients with NSCLC than in healthy individuals, with no differences between adeno and squamous cell carcinomas. Levels of circulating eHsp70 which are associated with the Programmed cell death protein 1 (PD-L1) status, gradually increased from early stage to metastatic disease, and patients with lymph node metastases in surgically treatable NSCLC had significantly higher eHsp70 levels than nodal negative patients. In all tumor stages, total lymphocyte counts were significantly reduced and immunoregulatory T (Treg) cell counts were increased compared to healthy controls. Lower CD4 + T helper cell and higher CD3-/CD56+/CD94+/CD69+/NKp30+/NKp46 + NK cell ratios were only found in patients with thoracic metastases of other primary tumors. An early relapse after complete resection with curative intent correlated with significantly elevated eHsp70 levels which were measured prior to surgery, in all thoracic cancer patients.

In summary, we propose circulating eHsp70 levels before any treatment as a predictive biomarker for the presence of lymph node metastases and early therapy failure in patients with thoracic malignancies.

The online version contains supplementary material available at 10.1186/s12885-025-14725-5.