Primary culture of cancer cells is expected to be useful for investigating the biology of cancer and predicting chemosensitivity for individual patients, yet has been hampered by technical difficulties. We recently developed the cancer tissue–originated spheroid (CTOS) method for the primary culture of colorectal cancer cells. In the present study, we applied this system to the primary culture of non–small-cell lung cancer.

We used 125 surgical specimens and 18 pleural effusions for CTOS preparation. Partially digested tumor fragments were cultured in a medium for embryonic stem cells. CTOSs were subjected to sensitivity assay and signal transduction assay for the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) erlotinib. We also investigated the effects of growth factors in culturing lung cancer CTOS.

The success rate of CTOS preparation from surgical specimens was 80.0%. The CTOS method was also suitable for culturing tumor spheroids from pleural effusions. CTOSs from lung cancer consisted mostly of pure cancer cells. CTOSs and CTOS-derived xenografts retained the characteristics of the original tumors. In vitro assay results showed that EGFR mutation status and expression levels corresponded with erlotinib sensitivity, confirming previous clinical findings. Furthermore, we found that neuregulin 1, a ligand of HER3, potently induced CTOS growth.

The CTOS method enables us to obtain primary lung tumor cells of high viability and purity. CTOS could be a new platform for studying lung cancer biology.