OPTICAL-3: mFOLFOXIRI Plus PD-1 Inhibitor vs mFOLFOX6 as Neoadjuvant Therapy for cT4/N2 Colon Cancer: A Randomized Phase II Trial

In patients with high-risk stage II and stage III colon cancer (CC), curative surgery followed by adjuvant chemotherapy with FOLFOX or CAPOX regimens has become the standard treatment. However, 20 to 30% of these patients will develop distant metastasis, which ultimately results in death. In contrast to rectal cancer, the role of preoperative therapy in colon cancer is less well established. Relatively few phase III trials of preoperative therapy have been reported, although current NCCN guidelines do recommend neoadjuvant chemotherapy (NAC) with FOLFOX or CAPOX regimen as an option for bulky T4b tumors. NAC is an attractive approach for several reasons. The ability to deliver systemic therapies earlier in the treatment course to eradicate micrometastatic disease is conceptually appealing. In addition, surgery can stimulate tumor proliferation through inflammation and other immune pathways. Preoperative delivery of chemotherapy may also lead to higher rates of R0 resections, and chemotherapy tolerance can be better in the neoadjuvant setting, especially in GI surgeries that require prolonged recovery.

The phase III portion of the FOxTROT trial, which was published in 2023. The pCR rate for 6 weeks of neoadjuvant FOLFOX chemotherapy was only 4%, and a moderate or greater tumor regression was reported in 21% of patients in the NAC group. Our team also conducted the phase III OPTICAL trial, which utilized a longer period of NAC (12 weeks) with FOLFOX or CAPOX. In this trial, the pCR rate for the neoadjuvant chemotherapy group was 7%, and the downstaging rate (ypT0-2N0) was 20%. However, for patients with locally advanced colon cancer, particularly those with T4b and bulky nodal disease, the use of oxaliplatin- and fluoropyrimidine-based doublet chemotherapy does not adequately meet the clinical need for tumor shrinkage and downstaging. There is an urgent need to explore drugs with different mechanisms of action in combination with chemotherapy to improve efficacy.