A Study of AN4035 in Advanced Cancers With RAS Mutations and High CEACAM5 Expression

The goal of this clinical trial is to determine whether AN4035 is safe and tolerable in people with advanced or metastatic solid tumors that have Rat Sarcoma oncogene (RAS) mutated solid tumors and high levels of the CEACAM5 protein. RAS genes help control how cells grow and divide. Mutations in RAS can cause cells to grow uncontrollably and contribute to cancer. CEACAM5 is a protein found on the surface of some cancer cells and may serve as a target for AN4035. This is the first time AN4035 is being tested in humans. The study will help identify the best dose(s) for future studies, understand how the body processes the drug, and evaluate whether AN4035 shows signs of fighting cancer. The main questions to answer are: * Which dose(s) of AN4035 are safe and tolerable for participants with RAS-mutated, CEACAM5-positive advanced solid tumors? * What side effects or medical problems do participants experience while receiving AN4035 alone or in combination with cetuximab (Erbitux)? * How does AN4035 move through and affect the body? * Does AN4035 help slow, stop, or shrink tumors? Participants will: * Receive AN4035 by intravenous (IV) infusion every 2 weeks, either alone or in combination with commercially available drug cetuximab. * Visit the clinic regularly for physical examinations, blood tests, safety assessments, and monitoring of their health and cancer status. * Provide blood samples to measure drug levels and help researchers understand how the body processes AN4035. * Undergo scans and other tests to evaluate how their tumors respond to treatment. * Continue treatment until their cancer worsens, they experience unacceptable side effects, choose to leave the study, or their doctor recommends stopping treatment. * Attend follow-up visits after treatment ends and may be contacted periodically to monitor their health and disease status. The study has two parts. In the first part, researchers will gradually increase the dose of AN4035 to determine the highest