Annalice Gandini, GI Medical Oncologist at Hôpital Européen Georges-Pompidou / Centre de Recherche des Cordeliers, Paris, and Lead of YOGI-EU, presented the results of the AGEO-NEO-MSI study at ESMO GI 2026.
Treatment strategy and immune-related toxicity shape response to neoadjuvant immunotherapy in dMMR/MSI colorectal cancer: Results from the AGEO-NEO-MSI study.
“I’m Anna Vicegandini, I’m a medical oncologist in Paris, and yesterday I had the opportunity to present at the Rapid Oral Session the results of our study, AGO Neo-MSI Study, evaluating neoadjuvant immunotherapy in DMMR-MSI colorectal cancer.
As you know, in the last few years, we have had an increasing number of trials evaluating these treatment regimens, but we were lacking real-world data, so that’s why we designed and conducted this study. We included 316 patients with DMMR-MSI colorectal cancer with no distant metastasis, who were treated with neoadjuvant immunotherapy, either with a single ICI in 77% of the cases or doublet ICI in 23% of the cases.
The primary endpoint of the study was complete response rates, defined as pathological complete response for patients who were operated on, or clinical complete response for patients who underwent non-operative management.
The rate of complete response was 67%, and the rate of pathological complete response was 66%, so our results were in line with the available literature, confirming the feasibility and efficacy of this treatment regimen.
However, event-free survival, despite an immature follow-up with a median follow-up of only 16 months, was not equal to the 100% EFS observed in some trials, and we had a 2-year EFS rate of 86%. This highlights the importance of real-world studies, where we can truly evaluate experimental strategies in routine clinical practice.
Moreover, we evaluated the safety of neoadjuvant immunotherapy and registered immune-related adverse events in 35% of patients, including 6% with grade 3 or higher adverse events, 9% treatment discontinuation due to toxicity, and one toxic death.
Importantly, all severe adverse events were more frequent among patients receiving doublet ICI, occurring in 12% of patients compared with 4% of those receiving single ICI.
We can therefore conclude that doublet ICI is associated with a higher rate of toxicity. However, we also observed that a short doublet ICI strategy was associated with a higher rate of complete response compared with a long single ICI strategy.
This underlines the importance of balancing different treatment regimens based on patient characteristics and the clinician’s judgment. Some translational analyses of these studies are ongoing, and we hope they will help us better select patients in the future.”
Watch the full video on OncoDaily GI.