As the US National Cancer Institute (NCI) switches to using patient-derived tumour xenografts in mice for drug screening (see Nature 530, 391; 2016), we warn researchers on behalf of the International Cell Line Authentication Committee (go.nature.com/kphqtx) that xenografts potentially have the same cross-contamination and misidentification problems as cultured cell lines.
For example, at least 4 of the 60 human-cancer cell lines on NCI's panel are affected, as are several NCI-derived lines that were established before contamination testing became widely available (see go.nature.com/csodfc).
Lack of testing or bad practice can undermine the reliability of patient-derived xenografts. Cell cultures from these call for extra quality-control measures, such as screening for cross-species DNA contamination (J. Camps et al. Leuk. Res. 30, 923–934; 2006).
The US National Institutes of Health now requires the authentication of key biological resources, but guidelines and defined protocols are still needed for rigorous characterization of patient-derived xenografts. It will be essential to deposit reference information for cell-based models in public databases, including details of donor DNA profile, host species and strain, testing outcome for host DNA, and methodologies.