Inclusion Criteria:

          1. ≥ 18 years of age

          2. Histopathological or cytologically documented locally advanced or metastatic solid
             tumors who have no available standard therapeutic treatment options

          3. At least one measurable lesion as defined by RECIST V1.1 criteria for solid tumors

          4. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

          5. Adequate organ function confirmed at screening and within 10 days of initiating
             treatment, as evidenced by:

               -  Absolute neutrophil count (ANC) ≥ 1.5 x 10^9/L

               -  Hemoglobin (Hgb) ≥ 8 g/dl

               -  Platelets (plt) ≥ 75 x 10^9/L

               -  AST/SGOT and ALT/SGPT ≤ 2.5 x Upper Limit of Normal (ULN) or ≤ 5.0 x ULN if liver
                  metastases are present

               -  Total bilirubin ≤ 1.5 x ULN

               -  Calculated 24-hour clearance ≥ 50 mL/min (Cockcroft Gault formula)

          6. Negative pregnancy test within 72 hours before starting study treatment in all
             premenopausal women and women < 12 months after the onset of menopause

          7. Must agree to take sufficient contraceptive methods to avoid pregnancy during the
             study and until at least 6 months after ceasing study treatment

          8. Able to sign informed consent and comply with the protocol

        Exclusion Criteria:

          1. Women who are pregnant or lactating

          2. Women of child-bearing potential (WOCBP) who do not use adequate birth control

          3. Patients with any hematologic malignancy, including leukemia (any form), lymphoma, and
             multiple myeloma

          4. Patients with a history of primary central nervous system tumors or carcinomatous
             meningitis.

          5. Patients with the following mood disorders as judged by the Investigator or a
             psychiatrist:

               -  Medically documented history of or active major depressive episode, bipolar
                  disorder (I or II), obsessive-compulsive disorder, schizophrenia; a history of
                  suicidal attempt or ideation, or homicidal ideation (immediate risk of doing harm
                  to others)

               -  ≥ CTCAE grade 3 anxiety

          6. Impaired cardiac function or significant diseases, including but not limited to any of
             the following:

               -  left ventricular ejection fraction (LVEF) < 45% as determined by multigated
                  acquisition (MUGA) scan or echocardiogram (ECHO)

               -  Congenital long QT syndrome

               -  QTcF ≥ 480 msec on screening ECG

               -  Unstable angina pectoris ≤ 3 months prior to starting study drug

               -  Acute myocardial infarction ≤ 3 months prior to starting study drug

          7. Patients with:

               -  unresolved diarrhea ≥ CTCAE grade 2, or

               -  impairment of gastrointestinal (GI) function, or

               -  GI disease that may significantly alter the absorption of TT-00420

          8. Other concurrent severe and/or uncontrolled concomitant medical conditions (e.g.,
             uncontrolled hypertension, uncontrolled hypertriglyceridemia, or active or
             uncontrolled infection) that could cause unacceptable safety risks or compromise
             compliance with the protocol

          9. Patients who have received chemotherapy, targeted therapy, or immunotherapy ≤ 4 weeks
             (6 weeks for nitrosourea or mitomycin-C) prior to starting study drug or who have not
             recovered from side effects of such therapy

         10. Patients who have received wide field radiotherapy ≤ 4 weeks or limited field
             radiation for palliation ≤ 2 weeks prior to starting study drug or who have not
             recovered from side effects of such therapy

         11. Patients who have undergone major surgery ≤ 4 weeks prior to starting study drug or
             who have not recovered from side effects of such therapy

         12. Patients who have been treated with any hematopoietic colony-stimulating growth
             factors (e.g., G-CSF, GM-CSF) ≤ 4 weeks prior to starting study drug.

         13. Patients who are currently receiving treatment with therapeutic doses of warfarin
             sodium or any other coumarin-derivative anticoagulants

         14. Patients who have received systemic corticosteroids ≤ 2 weeks prior to starting study
             drug or who have not recovered from the side effects of such treatment.

         15. Patients who are currently receiving treatment with strong CYP3A inhibitors or
             inducers ≤ 2 weeks prior to starting study drug.

         16. Known diagnosis of human immunodeficiency virus (HIV) infection (HIV testing is not
             mandatory; patients with well controlled HIV might be enrolled)

         17. Known history of active infection with Hepatitis B or Hepatitis C

         18. Has received a live-virus vaccination within 30 days of planned first dose

         19. Inability to swallow or tolerate oral medication

         20. Has a history or current evidence of any condition, therapy, or laboratory abnormality
             that, in the opinion of the investigator, might confound the results of the trial,
             interfere with the patient's safe participation and compliance in the trial.