Theranostic Approach by Early Multigene Sequencing in Advanced Poor Prognosis Cancers

Part 1 sequential multi-gene sequencing (Simple NGS), * Multi-gene DNA sequencing (43 genes panel corresponding to the most frequently targeted molecular alterations) * And if no contributive: Part 2: randomized study between two sequential approaches \- Experimental arm: early Multi-gene DNA sequencing (638 genes panel) Multi-gene RNA sequencing (ARCHER panel) 1. MMR status in molecular biology 2. \- Tumour Mutational Burden * Control arm: after 1st line escape, according to Plan France Medecine Genomique 2025 In the Part 2, a new biopsy could be proposed if necessary