A Phase 1a Open-Label, Dose-Escalation, and a Phase 2 Study to Investigate the Safety, PK, PD, and Clinical Activity of ST-067 Administered Subcutaneously as Monotherapy in Patients With Relapsed or Refractory Solid Tumors

Phase 1a is designed to determine the recommended Phase 2 dose of ST-067 monotherapy using a modified toxicity probability interval (mTPI) design. ST-067 is administered as subcutaneous injection once weekly. Pre and on treatment biopsies will be mandated for all patients. There will be evaluation of PK and PD effects.

Phase 2 will evaluate the preliminary efficacy of ST-067 administered at the RP2D to patients with the following tumor types. A Simon 2 stage design is used to calculate the sample size and early stopping rules will be employed in the event of lack of efficacy in any of the cohorts. RECIST 1.1 will be used to assess tumor response every 8-12 weeks.

Inclusion Criteria:

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

   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.

   1. For patients who have developed disease progression through standard therapy, or
   2. For patients whom standard of care therapy that prolongs survival is not available or suitable (according to the investigator and after consultation with the Medical Monitor)

   For Phase 2, the following solid tumors are allowed:

   Melanoma, RCC, TNBC, NSCLC, SCCHN, and MSI-Hi tumors

5. Has at least 1 measurable lesion per RECIST 1.1 criteria which has not been biopsied or received prior irradiation
6. 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
3. Significant cardiovascular disease
4. Significant ECG abnormalities i
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.