505TiP REGINA: A phase II trial of neoadjuvant regorafenib (rego) in combination with nivolumab (nivo) and short-course radiotherapy (SCRT) in intermediate-risk, stage II-III rectal cancer (RC)

Despite recent improvements, management of locally advanced rectal cancer (LARC) remains challenging, and many patients (pts) still experience recurrence. In preclinical models, combining Rego with an anti-PD-1 inhibitor led to superior tumour growth suppression as compared with either treatment alone. In a phase I clinical trial, remarkable results were reported for the combination of Rego and Nivo in advanced MSS colorectal cancer. This synergistic effect is thought to be secondary to the anti-angiogenic effects of Rego and its potential to reduce TAMs, promote M1 macrophage conversion, and downregulate expression of immunosuppressive factors.