Elevated Circulating Activin A Levels in Patients With Malignant Pleural Mesothelioma Are Related to Cancer Cachexia and Reduced Response to Platinum-based Chemotherapy

Background: Previous preclinical studies have shown that activin A is overexpressed in malignant pleural mesothelioma (MPM), associates with cancer cachexia, and is observed in in vitro resistance to platinum-based chemotherapy. We evaluated circulating activin levels and their endogenous antagonists' follistatin/follistatin-like 3 in intrathoracic tumors.

Materials And Methods: Patients suspected of thoracic malignancy were recruited prior to surgery. Serum samples were collected from 21 patients with MPM, 59 patients with non-small-cell lung cancer (NSCLC), and 22 patients with benign lung lesions. Circulating activin/follistatin levels were measured using enzyme-linked immunosorbent assay and compared with clinicopathologic parameters.

Results: Circulating activin A levels were elevated in patients with MPM when compared with patients with NSCLC or benign lung lesion samples (P < .0001). Also, follistatin and follistatin-like 3 levels were the highest in MPM, although with less difference compared with activin A. Receiver operating characteristic analysis for activin A for separating NSCLC from benign lung lesion showed an area under the curve of 0.856 (95% confidence interval, 0.77-0.94). Activin A levels were higher in patients with cachexia (P < .001). In patients with MPM, activin A levels correlated positively with computed tomography-based baseline tumor size (R = 0.549; P = .010) and the change in tumor size after chemotherapy (R = 0.743; P = .0006). Patients with partial response or stable disease had lower circulating activin A levels than the ones with progressive disease (P = .028).

Conclusion: Activin A serum level could be used as a biomarker in differentiating malignant and benign lung tumors. Circulating activin A levels were elevated in MPM and associates with cancer cachexia and reduced chemotherapy response.