• Patients who meet ALL the following inclusion criteria will be eligible to participate in the study:

⁃ ≥18 years of age.

⁃ Histologically confirmed, locally advanced, or metastatic solid tumor which has progressed on, or patients intolerant to, all standard therapy, or no standard therapy available, or it is documented that the therapy is refused by the patient.

⁃ Measurable disease per RECIST v1.1.

⁃ Life expectancy ≥3 months.

⁃ Adequate organ and bone marrow function defined by:

∙ Absolute neutrophil count (ANC) ≥1.5 × 109/L (≥1500/mm3)

‣ Platelet count ≥100 × 109/L (≥100,000/mm3) (no platelet transfusion within 14 days prior to enrollment)

‣ Total bilirubin ≤1.5 × upper limit of normal (ULN), unless known Gilbert syndrome (≤3 × ULN) has been diagnosed

‣ AST and ALT ≤2.5 × ULN or ≤5 × ULN for patients with known liver metastases

‣ Estimated creatinine clearance by the Cockcroft-Gault or estimated glomerular filtration rate (eGFR) of ≥60 mL/min

‣ International Normalized Ratio (INR), prothrombin time (PT), and activated partial thromboplastin time (aPTT) ≤1.5 × ULN. If a patient is receiving anticoagulant therapy, PT and aPTT must be within therapeutic range of intended use of anticoagulants

⁃ Patients with treated, stable central nervous system (CNS) metastases (including leptomeningeal carcinomatosis) are allowed if there is no evidence of progression for at least 4 weeks after CNS-directed treatment as ascertained by clinical examination and brain imaging.

⁃ Resolution of any clinically significant toxic effects of prior therapy to Grade ≤1 according to the NCI CTCAE v5.0 (exception of alopecia and Grade 2 peripheral neuropathy).

⁃ Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.

⁃ Willingness of men and women of reproductive potential to observe conventional and effective birth control methods with failure rates of \<1% for the duration of treatment and for at least 6 months for women and at least 3 months for men following the last dose of study treatment (this must include a barrier method such as condom or diaphragm with spermicidal gel). Women of reproductive potential are defined as following menarche and who are not postmenopausal (and 2 years of nontherapy-induced amenorrhea or surgically sterile). For male patients with a nonpregnant female partner of childbearing potential and a woman of childbearing potential, 1 of the following highly effective birth control methods with a failure rate of less than 1% per year when used consistently and correctly are recommended:

∙ Combined estrogen and progestin containing hormonal contraception associated with inhibition of ovulation given orally, intravaginally, or transdermally

‣ Progestin-only hormonal contraception associated with inhibition of ovulation given orally, by injection, or by implant

‣ Intrauterine device

‣ Intrauterine hormone-releasing system

‣ Bilateral tubal occlusion/ligation

‣ Vasectomized partner

‣ Sexual abstinence Note: Sexual abstinence is considered a highly effective method only if defined as refraining from heterosexual intercourse during the entire period of risk associated with the study drug. The reliability of sexual abstinence needs to be evaluated in relation to the duration of the study and the preferred and usual lifestyle of the patient. Birth control methods unacceptable for this study include the following:

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∙ Periodic abstinence (calendar, symptothermal, or post-ovulation methods)

‣ Withdrawal (coitus interruptus)

‣ Spermicide only

‣ Lactational amenorrhea method Egg and sperm donation or banking is prohibited during the duration of participation on this protocol and for 90 days after the last dose of study drug. 10. A negative serum pregnancy test at screening and a negative (serum or urine) pregnancy test within 72 hours before the first dose of study drug (female patients of childbearing potential only). If the urine test is positive or cannot be confirmed negative, a serum pregnancy test will be required and must be negative for the patient to be eligible.

• 11\. Willing and able to provide informed consent and comply with protocol requirements for the duration of the study.

• To be eligible during the dose expansion part of the study, patients must meet 1 of the following 2 criteria:

• Expansion Cohort 1: Documented locally advanced or metastatic gastric or

• EGJ cancer which has progressed on or after standard therapy or patient is intolerant to standard therapy or patient refuses therapy. Standard therapy options are described in (Wang,2024):

• Prior systemic standard therapy for patients with HER2-positive gastric or EGJ cancer should include trastuzumab plus chemotherapy (fluorouracil plus platinum), mono-chemotherapy (eg., paclitaxel, docetaxel, irinotecan), and other monotherapy (eg., VEGF targeted agents, anti-PD-1 or PD-L1).

• Prior system standard therapy for patients with HER2-negative gastric or EGJ cancer should include fluorouracil plus platinum or in combination with anti-PD-1, mono-chemotherapy (eg., paclitaxel, docetaxel, irinotecan) and VEGF targeted therapy.

• Expansion Cohort 2: Documented locally advanced or metastatic colorectal cancer which has progressed on or after standard therapy or patient is intolerant to standard therapy, or patient refuses therapy. Standard treatment options are described in (Association NHCOTPROCSOOCM,2023):

• Prior systemic standard therapy for patients with MMR-deficient (dMMR)/microsatellite instability-high (MSI-H): pembrolizumab for 1st line therapy, no standard therapy for 2nd and 3rd line therapy.

• Prior system standard therapy for patients with microsatellite stability (MSS) or microsatellite instability-low (MSI-L)/proficient mismatch repair (pMMR), RAS and BRAF wild-type (WT) should include cetuximab or bevacizumab monotherapy or in combination with FOLFOX/FOLFIRI/CAPEOX, and monotherapy (eg., regorafenib, fruquintinib, trifluridine tipiracil).

• Prior system standard therapy for patients with MSS or MSI-L/pMMR, RAS and BRAF mutation: should include bevacizumab monotherapy or in combination with FOLFIRI, and monotherapy (eg., regorafenib, fruquintinib, trifluridine tipiracil).