Study of TBX-3400 in Patients With Stage III and IV Melanoma Resistant or Refractory to Immune Checkpoint Inhibitors

Inclusion Criteria:

Patients must meet all of the following inclusion criteria to be eligible for participation
in the study:

1. Histopathologically confirmed diagnosis of advanced, unresectable or metastatic
malignant melanoma

2. Male or female patients age 18 or older

3. Previously treated with checkpoint inhibitor therapy either alone or in combination:

1. must have either stable disease or progressive disease per RECIST version 1.1 on
previous therapy (there is no minimum treatment duration for patients who have
progressive disease while on checkpoint inhibitor therapy); or

2. were deemed to have progressed on checkpoint inhibitor therapy at least 3 weeks
prior to the first dose of TBX-3400

4. Measurable or evaluable disease by RECIST version 1.1

5. Capable of understanding and complying with protocol requirements

6. A life expectancy of greater than 24 weeks at Screening

7. ECOG Performance Status of 0 to 2

8. Written informed consent from the patient or the patient's legally acceptable
representative prior to the initiation of any study procedures

9. Adequate bone marrow, liver, and renal function as defined below:

- hemoglobin ≥8.0 g/dL (transfusions allowed)

- absolute neutrophil count ≥1500/µL

- platelet count ≥100,000/µL (transfusions allowed)

- alanine transaminase and aspartate transaminase ≤3.0 times the upper limit of
normal (ULN), or ≤5 times ULN for patients with known hepatic metastases

- total serum bilirubin ≤1.5 x the ULN; ≤2.0 x the ULN if liver metastases are
present; patients with a known history of Gilbert's syndrome (≤3.0 x the ULN)
and/or isolated elevations of indirect bilirubin are eligible for study
participation

- estimated glomerular filtration rate ≥50 mL/min/1.73 m^2 (using Cockcroft Gault
formula)

Exclusion Criteria:

Patients who meet any of the following criteria will not be eligible for participation in
the study:

1. Pregnant or breast feeding

2. Developed autoimmune disorders while on prior checkpoint inhibitor therapy that have
not yet returned to Grade 1 or better

3. Require systemic pharmacologic doses of corticosteroids at or above the equivalent of
10 mg/day of prednisone; replacement doses, topical, ophthalmologic and inhalational
steroids are permitted

4. Active, symptomatic central nervous system (CNS) metastases. Patients with CNS
metastases are eligible for the trial if the metastases have been treated by surgery
and/or radiotherapy and the patient is off corticosteroids and is neurologically
stable for at least 7 days prior to screening

5. Any concurrent uncontrolled illness, including mental illness or substance abuse which
in the opinion of the investigator would make the patient unable to cooperate or
participate in the trial

6. Severe uncontrolled cardiac disease within 3 months of study entry, including unstable
or new onset angina, myocardial infarction or cerebrovascular accident

7. Women of childbearing potential who are unable or unwilling to use an acceptable
method of contraception

8. Known infection with human immunodeficiency virus (HIV) that is not well controlled on
anti-retroviral therapy as defined by HIV RNA more than 400 copies/mL or severely
symptomatic

9. Symptomatic congestive heart failure, defined as New York Heart Association Class II
or higher