METIMMOX: Colorectal Cancer METastasis - Shaping Anti-tumor IMMunity by OXaliplatin

This study aims to determine the efficacy, safety, and tolerability of the sequential addition of immune-modulating therapy to standard-of-care therapy of microsatellite-stable (MSS)/mismatch repair-proficient (pMMR) metastatic colorectal cancer (mCRC). Patients with MSS/pMMR-mCRC harbor tumor that can be transformed into an immunogenic disease by short-course oxaliplatin-based therapy, and may thereby benefit from the addition of immune-modulating therapy to improve outcome of the current oxaliplatin-based standard-of-care. Primary objective: To determine progression-free survival (PFS), in terms of failure of treatment strategy, of sequential treatment with the Nordic FLOX (5-Fluorouracil, oxaliplatin and leucovorin) regimen and nivolumab compared with the standard-of-care Nordic FLOX regimen in previously untreated MSS/pMMR-mCRC. Secondary objectives: To determine safety and tolerability of sequential treatment with the Nordic FLOX regimen and nivolumab compared with the standard-of-care Nordic FLOX regimen. To monitor and compare quality-of-life (QoL) alterations during therapy courses.