Open Label, Multicenter, Dose-escalation and Cohort-expansion Phase I/IIA Trial of STC-1010, an Immunotherapy, in Patients With Unresectable Locally Advanced or Metastatic Colorectal Cancer (CRC) - BreAK CRC Trial (BreAK for Brenus Anti-cancer)

Inclusion Criteria: 1. Male or female aged 18-75 years 2. Histologically confirmed diagnosis of unresectable locally advanced (stage IIIC, T4b) or unresectable metastatic (stage IV) (R0) adenocarcinoma of the colon or rectum 3. Adjuvant fluoropyrimidine monotherapy or oxaliplatin-based chemotherapy allowed if more than 6 months have elapsed between the end of adjuvant treatment and first relapse 4. Determination of KRAS and BRAF mutation status 5. Measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST 1.1) 6. Must agree to have biopsy at screening and on-treatment, only if not representing an unacceptable clinical risk and/or if technically feasible as judged by the Investigator in discussion with the interventional radiologist or endoscopist 7. Eastern Cooperative Oncology Group (ECOG) performance status (PS) ≤ 1. Participants \>70 years must have a PS= 0. 8. Life expectancy \> 3 months as assessed by the investigator 9. Effective contraceptive measures implemented Exclusion Criteria: 1. Patients with symptomatic ascites or pleural effusion 2. Dihydropyrimidine dehydrogenase (DPD) deficiency 3. Resectable tumor with curative intent or patient considered for a curative strategy by intensifying chemotherapy to induce resectability 4. Prior chemotherapy for metastatic disease 5. Prior immunotherapy for advanced/metastatic disease (except for Arm 2A-2) 6. Prior therapy with an investigational agent 7. BRAF mutation 8. Active auto-immune diseases such as rheumatoid arthritis, lupus, Crohn's disease, ulcerative colitis 9. Medical conditions requiring immunosuppressive therapy 10. Major surgery \<4 weeks prior to first administration of STC-1010 11. Radiotherapy \< 4 weeks prior to first administration of STC-1010 or \< 2 weeks in case of palliative radiotherapy 12. Prior stem cell or solid organ transplantation 13. Dementia or altered mental status or subject of a legal protection measure that would prohibit informed consent 14. Active drug or alcohol abuse as assessed by the Investigator 15. Participant deprived of their liberty by a judicial or administrative decision, undergoing psychiatric care and admitted to a health or social establishment for purposes other than research.