#ESMOGI26# An interesting exploratory analysis from ATOMIC asks an important question: How much chemotherapy do patients receiving adjuvant FOLFOX + atezolizumab actually need? (Remember, this is our only adjuvant prospective study in MSI-H CRC and is with FOLFOX + Atezolizumab vs FOLFOX. If you can catch these patients before surgery, almost certainly better to treat neoadjuvantly). Quick takeaways: • Patients receiving >6 cycles of FOLFOX appeared to derive the greatest DFS benefit from the addition of atezolizumab (adjusted HR 0.45). • That benefit was not apparent among patients receiving ≤6 cycles (HR 0.84), although this subgroup was relatively small. • Receiving ≥12 cycles of atezolizumab was associated with numerically better DFS than shorter treatment, but this analysis is difficult to interpret given treatment discontinuation for toxicity and other confounders. My interpretation: This actually makes biological sense. Atezolizumab has consistently appeared less active than PD-1 inhibitors in MSI-H CRC. If that's true, then maintaining adequate chemotherapy intensity may be particularly important in this regimen. I don't think these exploratory data answer whether 3 months of CAPOX is sufficient in dMMR disease. If anything, they reinforce that ATOMIC should probably be viewed as the regimen that was studied, than the exact regimen used in clinical practice. Slides nabbed from @GillSharlene @TheGutOncLab @OncoAlert @Onco_Nexus @ESMO