A Study of SAR444245 Combined With Other Anticancer Therapies for the Treatment of Participants With Gastrointestinal Cancer (Master Protocol) (Pegathor Gastrointestinal 203)

Inclusion Criteria:

* Participant must be ≥18 years of age (or country's legal age of majority if \>18 years), at the time of signing the informed consent.
* Participants with:

  * Sub-study01: Histologically or cytologically confirmed diagnosis of advanced unresectable or metastatic esophageal cancer of the squamous cell carcinoma subtype.
  * Sub-study02: Histologically or cytologically confirmed diagnosis of advanced unresectable or metastatic GC or Siewert Type 2 \& 3 GEJ.
  * Sub-study03: Histologically or cytologically confirmed diagnosis of advanced unresectable or metastatic hepatocellular carcinoma (HCC), or clinically by AASLD criteria in cirrhotic patients.
  * Sub-study04: Histologically or cytologically confirmed diagnosis of advanced unresectable or mCRC. Only patients with non-MSI-H disease are eligible.
* Participants (all sub-studies) must have at least one measurable lesion.
* Mandatory baseline biopsy for the first 20 participants to enroll in sub-study01, sub-study02 and sub-study04. On-treatment biopsy for at least 20 participants in sub-study04. On-treatment biopsies are otherwise optional per Investigator's discretion for the other cohorts.
* Females are eligible to participate if they are not pregnant or breastfeeding, not a woman of childbearing potential (WOCBP) or are a WOCBP that agrees:

  * to use approved contraception method and submit to regular pregnancy testing prior to treatment and for at least 120 days (for Cohort A, B1, B2, B3, C, and D1) or 60 days (for Cohort D2) \[corresponding to the time needed to eliminate any study intervention(s)\].
  * and to refrain from donating or cryopreserving eggs for 120 days after discontinuing study treatment.
* Males are eligible to participate if they agree to refrain from donating or cryopreserving sperm, and either abstain from heterosexual intercourse OR use approved contraception during study treatment and for at least 3 days \[corresponding to time needed to eliminate SAR444245\] after the last dose of SAR444245.
* Capable of giving signed informed consent.

Exclusion Criteria:

* Eastern Cooperative Oncology Group (ECOG) performance status of ≥2.
* Poor organ function.
* Active brain metastases or leptomeningeal disease.
* History of allogenic or solid organ transplant.
* Last administration of prior antitumor therapy or any investigational treatment within 28 days or less than 5 times the half-life, whichever is shorter; major surgery within 28 days prior to first IMP administration.
* Comorbidity requiring corticosteroid therapy (\>10 mg prednisone/day or equivalent) within 2 weeks of IMP initiation. Inhaled or topical steroids are permitted, provided that they are not for treatment of an autoimmune disorder. Participants who require a brief course of steroids (eg, as prophylaxis for imaging studies due to hypersensitivity to contrast agents) are not excluded).
* Antibiotic use (excluding topical antibiotics) ≤14 days prior to first dose of IMP.
* Severe or unstable cardiac condition within 6 months prior to starting study treatment.
* Active, known, or suspected autoimmune disease that has required systemic treatment in the past 2 years.
* Participants with baseline SpO2 ≤92% (without oxygen therapy). - Participant has received prior IL2-based anticancer treatment.
* Participants on sub-study02 cohort B1 and B2 or sub-study 04 - cohort D1 with prior treatment with an agent that blocks the PD-1/PD-L1 pathway.
* Receipt of a live-virus or live attenuated-virus vaccination within 28 days of planned treatment start. Seasonal flu vaccines that do not contain live virus are permitted.

The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.