Phase 1a and Phase 2 Study for Safety, Preliminary Efficacy, PK and PD of ST-067

Inclusion Criteria:

1. 1. Male and female patients aged ≥18 years
2. Must provide written informed consent and any authorizations required by local law
3. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
4. Have histologically or cytologically confirmed diagnosis of advanced/metastatic solid tumor

1. For Phase 1a, the following solid tumors are allowed: Melanoma, Merkel cell, RCC, urothelial, NSCLC,TNBC, SCCHN, microsatellite instability high, high tumor mutation burden (Hi TMB) or mismatch repair deficient, gastric, cervical, endometrial, cutaneous squamous, small cell lung, esophageal, hepatocellular carcinoma and platinum resistant ovarian cancer.
2. For patients who have developed disease progression through standard therapy, or
3. For patients whom standard of care therapy that prolongs survival is unavailable or unsuitable (according to the investigator and after consultation with the Medical Monitor) For Phase 1 combination therapy dose escalation, the following solid tumors are allowed: Melanoma, Merkel cell, RCC, urothelial, NSCLC (with no EGFR, TRK receptor, or ALK positive mutations/fusions), TNBC, SCCHN, MSI-Hi tumors, Hi TMB or mismatch repair deficient, gastric, cervical, endometrial, cutaneous squamous, small cell lung, esophageal, and HCC

1. TNBC is diagnosed in a tumor which does not express estrogen receptor or progesterone receptor, is not human epidermal growth factor receptor 2 (HER2) 3+ on IHC or is negative by fluorescence in situ hybridization (FISH).
2. MSI high tumor should have mutations in 30% or more microsatellites by PCR or be negative for MSH1/2/6 or PMS-2 by IHC.
3. Hi-TMB high tumor has 10 mut/Mb or greater calculated from whole genome sequencing or whole exome sequencing

For Phase 2, the following solid tumors are allowed:

1. Melanoma, RCC, TNBC, NSCLC, SCCHN, and MSI-Hi tumors
2. Has at least 1 measurable lesion per RECIST 1.1 criteria which has not been biopsied or received prior irradiation
3. Has an accessible tumor for biopsy pre- and on-treatment (mandatory).

Exclusion Criteria:

1. History of another malignancy
2. Known symptomatic brain metastases requiring >10 mg/day of prednisolone or equivalent
3. Significant cardiovascular disease (MI, thrombotic events,) within 6 months prior to study treatmentSignificant ECG abnormalities (Phase 1a and 2 monotherapy only) including unstable cardiac arrhythmia requiring medication, second-degree atrioventricular block type II, third degree AV
4. Any degree of respiratory compromise (from either malignant or non-malignant disease)
5. Evidence of an ongoing systemic bacterial, fungal, or viral infection
6. Has received a live vaccine within 30 days
7. Major surgery within 4 weeks
8. Prior solid organ or bone marrow progenitor cell transplantation
9. Prior high dose chemotherapy requiring stem cell rescue
10. History of active autoimmune disorders
11. Ongoing immunosuppressive therapy, including systemic or enteric corticosteroids.
12. Treatment with an approved, systemic anticancer therapy or an investigational agent within 4 weeks of Day 1
13. A positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral test within 28 days prior to dosing, unless there is Investigator-confirmed clinical recovery on or before C1D1
14. Subjects with adrenal insufficiency
15. Subjects with any chemistry or hematology laboratory values that are ≥Grade 2

Additional exclusion criteria for Phase 1 combination therapy only: