Study to Assess the Safety and Preliminary Efficacy of STI-1386 Oncolytic Virus in Relapsed or Refractory Solid Tumors

Inclusion Criteria: * Histologically confirmed extracranial solid tumors that are relapsing or refractory including locally advanced pancreatic cancer, unresectable soft tissue sarcomas, hepatic metastases due to colorectal cancer * At least one measurable disease per Response Evaluation Criteria in Solid Tumors v. 1.1 (RECIST 1.1) with a non-nodal lesion with longest diameter ≥ 10 mm or nodal lesions with short diameter ≥ 15 mm * Eastern Cooperative Oncology Group (ECOG) Performance Status ≤ 2 * As assessed by the investigator, ≥ 3 month life expectancy * Adequate hematologic, liver and renal function at Screening as determined by lab criteria * Recovered \< Grade 2 from all acute toxicities from previous therapy * Has not had prior treatment with high dose corticosteroids within the 2 weeks of screening * Is willing and able to comply with the study schedule and other protocol requirements * Willing to follow contraception guidelines Exclusion Criteria: * Have a primary brain tumor * Use of an investigational drug or local therapy or agent within 2 weeks of first dose of study drug. Current systemic chemotherapy per investigator's discretion is allowed, but no immune checkpoint inhibitors or immune modulators * Use of anticoagulants or anti-platelet agents unless subject can safely start/stop to allow intratumoral injections * Use of bevacizumab (Avastin) within 28 days of the STI-1386 injection * Diagnosis of other malignancies that have required therapy in the last year or are not in complete remission. Exceptions include non-metastatic basal cell or squamous cell carcinomas of the skin, prostate cancer or cancer in situ that does not require treatment currently or is otherwise under control * Requiring chronic systemic immunosuppressants, including steroids \> 20 mg/day * Presence of bulky disease defined as any single mass \> 5 cm in greatest dimension will trigger a discussion to determine eligibility * New York Heart Association (NYHA) Class \>3 of left ventricular ejection fraction (LVEF) \< 50% * Prolonged corrected QT interval as determined by 12-lead electrocardiogram * Has spinal cord compression or clinically unstable brain metastases within 4 weeks of first dose of study drug * Evidence of active herpes infection and/or chronic herpes infection requiring prophylactic antiviral medication that may not be discontinued * Has an active or recent COVID-19 infection, must have a negative RT-PCR test and not have had symptoms within 4 weeks of day 1 of study drug administration * Any active infection requiring systemic therapy within 72 hours of injection of STI-1386, excluding anti-viral maintenance therapy for HIV * Moderate to severe chronic obstructive pulmonary disease or other moderate to severe chronic respiratory conditions unless under treatment and stable for the 3 months of screening * Have active human immunodeficiency virus (HIV) infection, human T-cell leukemia virus type 1 (HTLV1) infection, or hepatitis B virus (HBV) or hepatitis C virus (HCV) viremia * Pregnant or lactating or up to 3 months post last dose * Underlying medical conditions that, in the opinion of the investigator and/or medical monitor will prevent the subject from participating * Allergy to acyclovir and related anti-HSV antiviral agents