Inclusion Criteria:

          1. Signed informed consent and mental capability to understand the informed consent

          2. Male or female patients > 18 years of age

          3. Histologically or cytologically documented locally advanced or metastatic solid tumor
             malignancies refractory to or otherwise ineligible for treatment with standard-of-care
             agents/regimens, including but not limited to:

               -  Malignant melanoma

               -  Hormone receptor negative breast cancer

               -  Gastro-esophageal cancer

               -  Non-small cell lung cancer

               -  Head and neck cancer

               -  Hepatoma

               -  Renal cell carcinoma

          4. Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 1

          5. Evaluable or measurable disease as follows:

               -  A minimum of 3 RECIST-evaluable lesions: one that is suitable for injection and
                  biopsied; one non-injected that will be biopsied for abscopal effect; and one
                  measurable lesion that will be followed for response only.

               -  Injectable tumors shall be accessed by intralesional (cutaneous) or percutaneous
                  injection only, including those lesions that are visible, palpable, or detectable
                  by standard radiographic or ultrasound methods. Neither surgical procedures nor
                  endoscopically-guided injections including those to endobronchial, endoluminal,
                  or endosinusial spaces shall be allowed. While no anatomic locations are required
                  or disallowed, lesions selected for intratumoral injection must, in the opinion
                  of the investigator:

               -  Not be immediately adjacent to blood vasculature or other physiologic landmarks
                  in such a way that will accrue undue safety risk to the patient

               -  Have longest diameter ≥ 10 mm and ≤ 50 mm

               -  Be fully efficacy evaluable per RECIST v1.1 criteria

          6. Life expectancy > 3 months (Phase I) and > 6 months (Phase IIA)

          7. ECG without evidence of clinically meaningful conduction abnormalities or active
             ischemia as determined by the investigator

          8. Acceptable organ and marrow function as defined below:

               -  Absolute neutrophil count > 1,500 cells/μL

               -  Platelets > 50,000 cells/μL

               -  Total bilirubin ≤ 1.5 times the upper limit of normal (ULN)

               -  Aspartate aminotransferase (AST)/alanine transaminase (ALT) ≤ 2.5 times ULN. If
                  liver metastases are present, AST/ALT < 5 times ULN

               -  Serum creatinine < 1.5 mg/dL and a measured creatinine clearance ≥ 50 mL/min
                  using the Cockcroft-Gault formula

               -  Prothrombin time (PT)/partial thromboplastin time (PTT) ≤ 1.5 times ULN

          9. Women of child-bearing potential (defined as a female who has experienced menarche and
             who has not undergone successful surgical sterilization (hysterectomy, bilateral
             salpingectomy, or bilateral oophorectomy) or is not postmenopausal (defined as
             amenorrhea for at least 12 consecutive months with an appropriate clinical profile at
             the appropriate age, e.g., greater than 45 years) must have a negative serum pregnancy
             test prior to first dose of study drug

         10. Male and female patients with reproductive potential must agree to use two forms of
             highly effective contraception throughout the study

         11. Phase I combination only: Demonstrated RECIST stable disease through ≥ 4 consecutive
             cycles of an approved PD-1 or PD-L1 targeted ICI with no Grade ≥ 3 CTCAE events
             considered by the investigator to be drug-related.

        Exclusion Criteria:

          1. Anti-cancer therapy within 4 weeks or < 5 half-lives of the first dose of study drug.

          2. Failure to recover to Grade 1 or less from clinically significant AEs due to prior
             anti-cancer therapy.

          3. Known untreated brain metastases or treated brain metastases that have not been stable
             (scan showing no worsening of central nervous system (CNS) lesion[s] and no
             requirement of corticosteroids) ≥ 4 weeks prior to study enrollment

          4. Baseline prolongation of QT/QTc interval (QTc interval > 470)

          5. Uncontrolled intercurrent illness (including, but not limited to, ongoing or active
             infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac
             arrhythmia, or psychiatric illness/social situations) that in opinion of the
             investigator would limit compliance with study requirements

          6. Women who are pregnant or breastfeeding

          7. Phase I combination only: Prior tumor progression through PD-1 or PD-L1 targeted ICI
             therapy.