This observational study evaluates if ex-vivo lung cancer drug sensitivity testing results correlate with the driver mutations found by genetic sequencing and if it can predict treatment response.

Non-small cell lung cancer (NSCLC) treatment decisions often rely on DNA sequencing, which only partially captures the tumor's mutational landscape and may miss other complex resistance mechanisms. Consequently, an unbiased functional drug screen is essential to rapidly identify optimal next-line therapies. Current drug sensitivity testing (DST) is limited by inefficient live tumor cells isolation. To address this, a rapid, unbiased DST platform utilizing FDA-approved targeted therapies was developed. Our approach uses malignant pleural effusions (MPEs) as a rich source of viable tumor cells. Because MPEs are highly heterogeneous, tumor cells are first identified via EpCAM flow cytometry, and the sample is enriched for tumor cells by depleting CD45+ immune cells using antibody-coated magnetic beads. These enriched tumor cells are then seeded into drug-containing plates. Following 72-hour incubation, cell viability is assessed using the CellTiter-Glo assay. Treatment efficacy is determined by the degree of reduction in cell viability at a range of drug concentrations, where the most effective treatment is the drug that reduces cell viability at the lowest concentration range.

To link clinical outcome and ex-vivo drug response assays, the investigators systematically measure drug sensitivity and resistance of primary tumor cells ex-vivo using a diverse compound library for individual patients in need of treatment. By systematically analyzing ex-vivo drug response patterns, tumors should be functionally grouped, by response phenotype. While for the purpose of this study selection of a specific treatment will not be based on ex-vivo drug response assays, clinical response- and follow-up data of patients will be prospectively collected in parallel.

Inclusion Criteria:

• Presence of pleural effusion in patient with a diagnosis of a lung cancer or suspected to be diagnosed with lung cancer according to their CT imaging, who are in need for pleural effusion drainage due to shortness of breath, and are willing to donate effusion for ex-vivo drug sensitivity testing.
• Patient's written informed consent present.
• Ability to understand the nature of the trial and the trial related procedures and to comply with them.

Exclusion Criteria:

• negative cytology for malignancy in the last 6 months

Patients with pleural effusion with a diagnosis of a lung cancer or suspected to be diagnosed with lung cancer according to their CT imaging, who are in need for pleural effusion drainage due to shortness of breath, and are willing to donate effusion for ex-vivo drug sensitivity testing.