TRAF2 and cancer: To address this gap, we conducted additional discovery analysis, identifying a number of other pan-cancer factors influencing CPI response, namely 9q34.3 (TRAF2) loss, CCND1 amplification, DNV count, and expression of CXCL13. 9q34.3 (TRAF2) loss was found to occur via the evolutionary phenomenon of collateral sensitivity (Zhao et al., 2016), where whole-chromosome 9 loss creates a strong pro-tumor driver effect in untreated patients, which then switches to vulnerability under CPI therapy.