Inclusion Criteria:

          1. Age 18 years or older

          2. Histologically confirmed diagnosis of metastatic or locally advanced malignancies

          3. Measurable disease per RECIST 1.1

          4. Disease progression after at least 12 weeks and at least 2 doses of a commercially
             available PD-1 or PD-L1 inhibitor per approved prescriber's information, whether
             monotherapy or in combination therapy, with no other intervening systemic anticancer
             therapy prior to enrollment

          5. Eastern Cooperative Oncology Group (ECOG) performance status 0-1

          6. Life expectancy > 12 weeks

          7. Adequate bone marrow function defined by ANC of ≥ 1.5×10^9/L, platelet count of
             ≥100.0×10^9/L, and hemoglobin of ≥ 9.0 g/dL (with or without transfusion)

          8. Adequate hepatic function defined as serum total bilirubin < 2 mg/dL, AST/ALT ≤ 2.5 ×
             ULN (or ≤ 5 × ULN in patients with liver metastases)

          9. Adequate renal function defined as creatinine clearance >60 mL/min as determined by
             Cockcroft-Gault equation

         10. Female patients must be surgically sterile (or have a monogamous partner who is
             surgically sterile) or be least 2 years postmenopausal or commits to use 2 acceptable
             forms of birth control (defined as the use of an intrauterine device, a barrier method
             with spermicide, condoms, any form of hormonal contraceptives, or abstinence) for the
             duration of the study and for 4 months following the last dose of study treatment.
             Male patients must be sterile (biologically or surgically) or commit to the use of a
             reliable method of birth control (condoms with spermicide) for the duration of the
             study and for 4 months following the last dose of study treatment

         11. Female patients who are women of childbearing potential (WCBP) must have a negative
             serum pregnancy test at Screening within 7 days of dosing with CTX-471

         12. Last dose of previous PD-1 or PD-L1 therapy ≥ 28 days, other anticancer therapy > 21
             days (or 2 half-lives for proteins, whichever is longer), radiotherapy > 21 days
             (concurrent localized palliative radiotherapy is allowed during CTX-471 treatment), or
             surgical intervention >21 days prior to the first dose of CTX-471

         13. Resolution of all prior anti-cancer therapy toxicities ≤ Grade 1

         14. Willingness to provide pre- and post-treatment fresh tumor biopsies

         15. Capable of understanding and complying with protocol requirements

         16. Signed and dated institutional review board/independent ethics committee-approved
             informed consent form before any protocol-directed screening procedures are performed

        Exclusion Criteria:

          1. Developed clinically significant adverse reaction to PD-1 or PD-L1 therapy, including
             immune related adverse reactions, which led to discontinuation of treatment

          2. Prior treatment with other investigational immune-oncology therapies

          3. Systemic therapy with immunosuppressive agents within 7 days before the start of
             CTX-471 treatment. Topical, intranasal, intraocular, or inhaled corticosteroids and
             physiologic replacement for patients with adrenal insufficiency are allowed

          4. Patient is a pregnant or lactating WCBP

          5. Prior organ transplantation

          6. Active hepatitis B virus, hepatitis C virus, or human immunodeficiency virus infection
             or a positive serological test at Screening within 28 days of dosing with CTX 471

          7. Active autoimmune disease or medical conditions requiring chronic steroid (ie, > 10
             mg/day prednisone or equivalent) or immunosuppressive therapy. Patients with a prior
             history of autoimmune disease may be eligible following discussion with the Medical
             Monitor

          8. History of central nervous system metastases

          9. History of seizure disorders

         10. Congestive heart failure (> New York Heart Association Class II), active coronary
             artery disease, unevaluated new onset angina within 3 months or unstable angina
             (angina symptoms at rest) or clinically significant cardiac arrhythmias

         11. Other systemic conditions or organ abnormalities that in the opinion of the
             Investigator may interfere with the conduct and/or interpretation of the current study