JTX-2011 Alone and in Combination With Anti-PD-1 or Anti-CTLA-4 in Subjects With Advanced and/or Refractory Solid Tumors

Inclusion Criteria: 1. Must be willing and able to participate and comply with all trial requirements and able to provide signed and dated informed consent prior to initiation of any trial procedures 2. Evaluable or measurable disease, according to Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 criteria, and meet the requirements for the intended study cohort 3. Male or Female ≥ 18 years of age 4. Have an Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0-1. Subjects with ECOG 2 may be considered for enrollment in Parts C, D, F, and H if approved by Medical Monitor 5. Have a predicted life expectancy of ≥ 3 months 6. Have laboratory values (obtained ≤ 28 days prior to first infusion day) in accordance with the study protocol 7. If medical history of the following, case should be reviewed by the Medical Monitor: prior biliary tract disorders (as based on Hepatobiliary SOC high level terms of: obstructive bile duct disorders, hepatic vascular disorders, structural and other bile duct disorders) or portal hypertension and/or hepatic vascular disorders 8. Women of child-bearing potential (WOCBP) must have a negative serum pregnancy test at screening and a negative urine pregnancy test prior to administration of each dose of JTX-2011 9. WOCBP and males with partners of child-bearing potential must agree to use adequate birth control throughout their participation and for 5 months following the last study treatment Exclusion Criteria: 1. Receiving concurrent anti-cancer treatment (excluding radiation therapy), either approved or investigational 2. Have refused standard therapy 3. Have received anti-cancer therapies listed below within the specified timeframe, or who have ongoing toxicity from prior therapy \> Grade 1 according to the Common Terminology for Adverse Events (CTCAE). Exceptions to this are: \> Grade 1 toxicities which in the opinion of the Investigator should not exclude the subject (e.g. alopecia, Grade 2 neuropathy, hypo- or hyperthyroidism or other endocrinopathies that are well-controlled with hormone replacement) and are approved by the Medical Monitor. 1. Have received biologic therapy, including immunotherapy, \< 28 days prior to C1D1; 2. Have received CAR-T therapy; 3. Have received chemotherapy \< 21 days prior to C1D1, or \< 42 days for mitomycin or nitrosoureas; 4. Have received targeted small molecule therapy \< 14 days prior to C1D1; 5. Have undergone organ transplantation including allogeneic or autologous stem-cell transplantation, at any time; 4. Have undergone a major surgery (excluding minor procedures, e.g. placement of vascular access, biopsy, etc.) \< 6 months prior to the first day of study treatment, C1D1 5. Have a history of intolerance, hypersensitivity, or treatment discontinuation due to severe immune adverse events on prior immunotherapy, or documented presence of neutralizing anti-drug antibody to nivolumab, ipilimumab, or pembrolizumab. Subjects who discontinued prior immunotherapies for immune-related adverse events that are well-controlled with appropriate treatment may be enrolled if approved by the Medical Monitor. 6. Have a diagnosis of immunodeficiency, either primary or acquired, or treatment with systemic steroids or any other form of immunosuppressive therapy within 7 days prior to C1D1. Exception: inhaled or topical steroids and adrenal replacement doses are permitted in the absence of active autoimmune disease as well as a one-time dose of immunosuppressive agents used prophylactically for contrast allergies 7. Have any active disease requiring systemic immunosuppressive treatment 8. Have known severe intolerance to or life-threatening hypersensitivity reactions to humanized monoclonal antibodies or intravenous immunoglobulin preparations; any history of anaphylaxis; prior history of human anti-human antibody response; known allergy to any of the study medications, their analogues, or excipients in the various formulations of any agent 9. Are symptomatic or have uncontrolled brain metastases, leptomeningeal disease, or spinal cord compression not definitively treated with surgery or radiation (brain metastases that are stable and asymptomatic, either treated or untreated, will be allowed) 10. Have current second malignancy at other sites, which requires treatment, or in the judgement of the Investigator, may require treatment within the next year. Concurrent malignancies that do not require treatment and are clinically stable are allowed. A past history of other malignancies is allowed as long as the subject is not receiving specific treatment other than hormonal therapy, and, in the judgement of the Investigator, is unlikely to have a recurrence. 11. Have active and clinically relevant bacterial, fungal, or viral infection, including known Hepatitis A, B, or C or human immunodeficiency virus (HIV) (testing not required) 12. Have received live vaccines within past 30 days (inactivated vaccines are allowed; seasonal vaccines should be up to date prior to first infusion day) 13. Women who are pregnant or breastfeeding 14. Have experienced symptomatic cardiac disease that is unresponsive to surgical or medical management 15. Have any medical or social condition that, in the opinion of the Investigator, might place a subject at increased risk, affect compliance, or confound safety or other clinical trial data interpretation