Scientists at the Spanish National Cancer Research Centre (CNIO), in collaboration with the University of Cambridge and biotech startup Tailor Bio, have developed a genomic test that predicts patient resistance to conventional chemotherapy. By analyzing chromosomal instability (CIN) patterns—complex chromosomal gains, losses, and rearrangements—this computational model identifies which cancer patients are unlikely to respond to standard chemotherapeutics such as platinum compounds, taxanes, and anthracyclines. The test leverages signatures formed by pervasive chromosomal aberrations as a predictive biomarker for chemoresistance, potentially enabling precision medicine approaches that avoid ineffective treatments and associated toxicities.