RecruitingPhase 2Drug trialSingle cEll pRofiling PErsistaNce To ImmuNothErapyThe SERPENTINE trial (ESR 21-21165) is a phase II clinical study aiming to evaluate the efficacy of durvalumab and tremelimumab, alone or in combination, in patients with colorectal or endometrial cancer. The trial targets patients with microsatellite instability-high (MSI-H) tumors and those with microsatellite stable (MSS) tumors. Colorectal and endometrial cancers present significant challenges due to their heterogeneity and variable responses to treatment. Immunotherapy, particularly checkpoint inhibitors like durvalumab and tremelimumab, has shown promise in some patients, but predicting response remains elusive. The SERPENTINE trial aims to address this gap by investigating the effectiveness of these immunotherapies in a carefully selected patient population.