Study of Intratumoral IVX037 in Patients With Advanced or Metastatic Solid Tumours

Inclusion Criteria: 1. Has either a histologically confirmed advanced colorectal, gastric/gastroesophageal adenocarcinoma, or ovarian cancer that has progressed or is not suitable for standard of care systemic therapies. Participants with colorectal cancer must have either a primary tumor or a biopsy of a metastatic tumor which has been shown to lack microsatellite instability (by PCR) or to have normal expression of mismatch repair enzymes (by immunohistochemistry). That is, a mismatch repair proficient mCRC tumor. 2. Progressed on or after at least one prior line of systemic therapy and must not have had more than 3 prior lines. Phase 1b only: participants with gastroesophageal cancer must have failed prior treatment with an immune checkpoint inhibitor. 3. Has at least one injectable tumor that meets RECIST1.1 criteria to be designated as a target lesion, and is: 1. a liver lesion 1.0 to 6.5 cm (longest diameter) meeting RECIST criteria on baseline CT scan or MRI and suitable for injection under CT or ultrasound guidance, and participant has an estimated total tumor burden of disease \< 1/3 of liver volume based on CT or MRI imaging, or 2. A measurable lymph node, i.e., with a short axis diameter (SAD) of 1.5 cm to 6.5 cm, or 3. Other solid tumor with a longitudinal diameter 1.0 cm to 6.5 cm. 4. No other lesions (including non-injected lesions) greater than 6.5 cm (longest diameter). Note (i): Only 2 target lesions may be designated in any one organ but if an organ such as the liver has more than 2 lesions which can be injected, the others, up to 3 additional, may be designated as NTLs and injected. Alternatively, target and non-target lesions elsewhere up to a total of 5 may be selected for injection. Note (ii): Tumor lesions located in areas previously subjected to radiation or other locoregional therapies are not considered measurable unless there is a demonstrated progression in that lesion, as determined by the Investigator. 4. Has a performance status of 0 or 1 on the Eastern Cooperative Oncology Group (ECOG) performance scale. 5. Has demonstrated adequate organ function defined in the protocol, from samples collected within 72 hours prior to the start of treatment. 6. Is a male or female from 18 to 85 years or age at the time of signing the informed consent. 7. Must be willing to abstain from activities or use proper birth control methods for the duration of the study: 1. Female participants of child-bearing potential must be willing to use an adequate method of contraception. Contraception, starting with the first dose of study therapy through 120 days after the last dose of study therapy. Note: Abstinence is acceptable if this is the usual lifestyle and preferred contraception for the participant. 2. Male participants of child-bearing potential must agree to use an adequate method of contraception. Contraception, starting with the first dose of study therapy through 120 days after the last dose of study therapy. Note: Abstinence is acceptable if this is the usual lifestyle and preferred contraception for the participant. 8. The participant (or their legally acceptable representative if applicable) has provided written, informed consent prior to the initiation of any study procedures. 9. Female participants of child-bearing potential must have a negative urine pregnancy test within 72 hours prior to receiving the first dose of study medication. If a urine test is positive or cannot be confirmed as negative, a serum pregnancy test is required. 10. Participants must have fully recovered to NCI-CTCAE Grade 1 or better from AEs due to all previous anticancer therapies prior to entering this study. Note: Participants with Grade ≤ 2 AEs that are deemed not clinically significant by the Investigator may qualify for the study with approval by the Sponsor. 11. The participant has a life expectancy of greater than 6 months. Exclusion Criteria: Medical Conditions 1. The potential participant is deemed to be a candidate for hepatic surgery or locoregional therapy for liver lesions with curative intent or requires other systemic anti-cancer therapy. 2. The participant has clinically significant ascites (Grade ≥2). 3. Participants with any other concurrent uncontrolled illness, including mental illness or substance abuse, which may interfere with the ability of the participant to cooperate and participate in the trial; other examples of such conditions would include unstable or uncontrolled hypertension, unstable angina, myocardial infarction or cerebrovascular accident within 6 months of study entry. 4. The participant requires continuous systemic treatment with either corticosteroids (\>10 mg daily prednisone or equivalent) or other immunosuppressive medications within 4 weeks prior to the first dose of study treatment. Single doses of corticosteroids for prophylaxis of allergic reactions during imaging studies with contrast are allowed within 4 weeks of study treatment. 5. The participant has not fully recovered from any effects of major surgery without significant detectable infection. Surgeries that require general anesthesia must have been completed at least 2 weeks before first dose of IVX037. 6. Participants with bleeding diathesis due to underlying medical conditions or the use of anticoagulation medications that is unable to be reversed by medical treatment. 7. Participants with tumors that lie close to an airway, major blood vessel or spinal cord, which, in the opinion of the Investigator, could cause occlusion, compression, or erosion of the vital structures. 8. Participants with multi-focal miliary disease without critical target lesions. Prior/Concomitant Therapy 9. Participants who have been previously treated with an immune checkpoint inhibitor (e.g., an anti-CTLA-4, anti-PD-1 or anti-PD-L1) must have completed their last dose at least 28 days prior to Day 1 and have demonstrated progressive disease during or following the immune checkpoint inh