This is a Phase 1b study to assess the safety and tolerability of STI-1386, an oncolytic virus, in subjects with relapsed and refractory solid tumors (RRSTs).

This is a Phase 1b, dose-ascending study to assess the safety, tolerability and recommended phase 2 dose (RP2D) of STI-1386 in subjects with relapsed and refractory solid tumors (RRSTs). STI-1386 is a second generation oncolytic virus.

This is a two-stage study, the first stage uses a single ascending dose, followed by the multiple ascending dose stage.

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