Mini Oral Session 2

At the recent ESMO Gastrointestinal Cancer Congress in Munich, five studies on colorectal cancer were presented in mini-oral session 2. The studies focused on both early-stage tumours and metastatic disease.

The first study was a retrospective analysis of the IDEA France and IDEA Greece trials. The investigators aimed to identify prognostic factors for selecting patients for adjuvant treatment using ctDNA and Immunoscore. They used a tumour-informed assay based on PCR NGS technology on over 500 patients. The findings showed that ctDNA was the strongest prognostic factor, independent of tumour risk classification and adjuvant treatment duration. Combining ctDNA and Immunoscore further stratified patient prognosis, especially for those with undetectable ctDNA after surgery. However, these results need further confirmation.

The second study, conducted by the ECOG-ACRIN group, assessed the efficacy of neoadjuvant immunotherapy in stage 2 and 3 rectal cancer. This single-arm phase two study involved treating patients with nivolumab and ipilimumab, followed by short-course radiation and consolidation immunotherapy. The study found an approximate 60% complete response rate, and the treatment was well-tolerated. Despite these promising results, more data is needed to compare with other immunotherapy trials for MSI-high tumours.

The NEST1 & 2 clinical trial was the third study, focusing on neoadjuvant immunotherapy in colon cancer with MSS tumours. This single-arm phase two study tested the combination of botensilimab and balstilimab with different treatment strategies. The results were impressive, with a 30% pathological complete response in the NEST1 trial and over 50% in the NEST2 trial. These preliminary findings suggest further investigation is warranted and raise the possibility of organ-sparing strategies for colon cancer.

The fourth study, the REGINA trial, aimed to reverse immune resistance in MSS tumours using combination treatments. This single-arm phase two study involved nivolumab, regorafenib, and short-course radiation. Overall, the study found a 30% pathological complete response, though there were high toxicity rates. The study met its efficacy interim analysis endpoint and will continue with a reduced regorafenib dose to improve safety.

The fifth and final study focused on metastatic colorectal cancer, known as the FFCD 1703 POCHI trial. This single-arm phase two study evaluated the combination of immune checkpoint inhibitors with chemotherapy and bevacizumab in patients with immune-hot tumours, selected based on the Immunoscore and CD3+ TIL density. The study showed a 75% objective response rate, with 20% achieving complete clinical response and a high disease control rate of 96%. These promising results will need further confirmation from larger randomised trials.

In conclusion, the studies presented at the session provided promising results, particularly in using ctDNA and Immunoscore for patient stratification and the potential of neoadjuvant and combination immunotherapy in both early-stage and metastatic colorectal cancer. Further research and larger trials are necessary to confirm these findings and integrate them into clinical practice.