Inclusion Criteria:

        All Subjects:

          1. Provide signed and dated informed consent prior to study-specific screening procedures

          2. ≥ 18 years old

          3. Karnofsky performance status (KPS) ≥ 70

          4. Must have adequate bone marrow and renal/hepatic function within protocol specified
             limits

          5. Disease-free period of > 2 years from any other previous malignancies, excluding
             curatively treated basal cell carcinoma, squamous cell carcinoma of the skin, or
             carcinoma in situ of the cervix. Subjects with prostate cancer Stage 1 that do not
             require treatment may also be included

          6. Women and men must use protocol approved methods of contraception

          7. Must be able and willing to comply with the study visit schedule and study procedures

          8. Must be able to take oral medications

          9. Must have available archived tumor tissue and willing and able to provide consent for
             study access to such tissue

         10. For subjects with a history of seizures, must be adequately controlled on a stable
             regimen of anti-epileptic drugs

             For Phase 1 Subjects Only:

         11. Histologically or cytologically documented diagnosis of solid tumor for which no
             standard therapy is recognized or have failed or intolerant to the standard-of-care
             treatment

         12. Inoperable metastatic or locally advanced, unresectable disease

         13. Subjects may have either evaluable or measurable disease

         14. Subjects with treated (surgically excised or irradiated) and stable brain metastases
             are eligible as long as the subject has adequately recovered from treatment and the
             treatment was ≥ 28 days prior to initiation of study drug(s) and baseline brain
             computed tomography (CT) with contrast or magnetic resonance imaging (MRI) ≤ 14 days
             of initiation of study drug is negative for new brain metastases

             For Phase 2 Subjects Only:

         15. Histologically confirmed diagnosis of GBM

         16. Subjects must have documented recurrence after first-line treatment

         17. Prior first-line treatment must have included radiation and temozolomide

         18. Subject is suitable for re-resection, per Investigator discretion, as a component of
             their clinical care

         19. No more than one prior resection (Note: biopsy does not count as prior resection)

        Exclusion Criteria:

        All Subjects

          1. Subjects who have had recent systemic anticancer therapies, interventional device
             treatment and/or radiotherapy either within 14 days prior to first dose of study
             drug(s) or have not recovered (to grade ≤ 1) from all clinically significant
             toxicities related to prior therapies

          2. Subjects who have had any major surgery (not including re-resection surgery required
             in Phase 2) within 28 days prior to first dose of study drug(s), or minor surgery
             within 14 days prior to first day of study drug(s)

          3. Subjects taking any strong cytochrome P450 3A4 inducers within 14 days prior to the
             first dose of study drug(s)

          4. Subjects taking any strong cytochrome P450 3A4 inhibitors within 14 days prior to the
             first dose of study drug(s)

          5. Subjects taking any agents with moderate to high risk to prolong QT corrected (QTc)
             interval or to cause Torsades de Pointes within 14 days prior to the first dose of
             study drug(s)

          6. Subjects who have been treated with an investigational agent or investigational
             interventional device within 21 days prior to the first dose of study drug(s)

          7. Subject is growth factor dependent or transfusion dependent, or has received growth
             factor support or transfusion support within 14 days prior to the first dose of study
             drug(s)

          8. History of significant cardiac disease

          9. Status epilepticus within 1 year prior to the first dose of study drug(s)

         10. Pregnant or breastfeeding

         11. Any other significant co-morbid conditions that in the opinion of the Investigator
             would impair study participation or cooperation

             For Phase 1 Subjects Only:

         12. Lymphoma as primary cancer

             For Phase 2 Subjects Only:

         13. Unable or unwilling to consent to the provision of resected tissue after surgery

         14. Prior treatment with plerixafor or another CXCR4 inhibitor

         15. Prior treatment with bevacizumab

         16. Prior treatment with lomustine and/or carmustine

             For All Cohorts Receiving Oral USL311:

         17. Any active medical condition or previous major abdominal surgery or procedure that
             might, in the investigator's opinion, have a significant effect on USL311 absorption