Rossi A, et al. - Since the identification of screening biomarkers for patients at risk may assist in early detection of lung cancer and may help in improving overall survival, researchers investigated the nature of tumor liberated protein (TLP), which has been previously described as a tumor-associated antigen (complex) present in the sera from lung cancer patients, in order to assess its value as a potential biomarker for lung cancer screening. They produced a rabbit anti-RTNKEASI serum, beginning from the peptide epitope RTNKEASI previously identified from the TLP complex, and appraised it in the lung cancer cell line A549 by means of immunoblot and peptide completion assay. using mass spectrometry, identification of the TLP sequence was conducted. Then, using ELISA, they performed analysis of the detected protein in patients with non-small cell lung cancer (NSCLC) and benign lung pathologies and healthy donors. In the lysate of A549 cells, the anti-RTNKEASI antiserum detected and immunoprecipitated a 55 kDa protein band which was recognized as aldehyde dehydrogenase isoform 1A1, unveiling the molecular nature of at least one component of the previously described TLP complex. From a non-tumor cohort of 26 patients and 45 NSCLC patients with different disease stages, blood samples were screened for the presence of aldehyde dehydrogenase (ALDH) isoform 1A1 and global ALDH. Outcomes revealed elevated ALDH levels in the sera of NSCLC patients, even with early-stage disease. Thus, they suggest evaluating these levels as part of a marker panel for non-invasive detection of NSCLC.