Inclusion Criteria:

          1. Signed, written informed consent

          2. Male or female age ≥ 18 years

          3. Histologically or cytologically confirmed diagnosis of medullary thyroid cancer (MTC).

          4. Incurable recurrent/metastatic disease that is progressive after at least 1 prior
             tyrosine kinase inhibitor (TKI) containing regimen, or the patient was intolerant of
             or declined such therapy.

          5. Adequate organ function defined as:

               1. Serum creatinine ≤ 2.5 mg/dl or estimated creatinine clearance ≥ 30 ml/min and
                  not on dialysis.

               2. AST ≤ 5x upper limit of normal range and total bilirubin ≤ 2.0 mg/dl; except for
                  patients in whom hyperbilirubinemia is attributed to Gilbert's syndrome.

               3. Left Ventricular Ejection Fraction (LVEF) ≥ 45% confirmed by ECHO/MUGA

               4. Must have a minimum level of pulmonary reserve defined as ≤ Grade 1 dyspnea and
                  pulse oxygen > 92% on room air

          6. ECOG Performance Status that is either 0 or 1.

          7. Toxicities from prior therapies must have recovered to grade ≤ 2 according to the
             CTCAE 5.0 criteria or to the patient's prior baseline.

          8. Patients must have evaluable disease as defined by RECIST 1.1.

          9. Subjects of reproductive potential must agree to use acceptable birth control methods.

        Exclusion Criteria:

          1. Active hepatitis B or hepatitis C infection.

          2. Any other active, uncontrolled infection.

          3. Any prior history of moderate to severe (Grade 2 or higher) pneumonitis.

          4. Subjects with chronic kidney disease with Grade 2 or higher renal impairment (eGFR or
             CrCl 59-30 ml/min/1.73 m2).

          5. Class III/IV cardiovascular disability according to the New York Heart Association
             Classification.

          6. Clinically apparent arrhythmia or arrhythmias that are not stable on medical
             management within two weeks of physician-investigator confirmation of eligibility.

          7. Planned concurrent treatment with systemic high dose corticosteroids. Patients may be
             on a stable low dose of steroids (≤10mg equivalent of prednisone). Use of inhaled
             steroids is allowable. Corticosteroid treatment as anti-emetic prophylaxis on the day
             of lymphodepleting chemotherapy administration is allowed per institutional practice.

          8. Any moderate to severe skin rash or allergies requiring systemic treatment.

          9. Receipt of immune checkpoint inhibitors within 2 months prior to
             physician-investigator confirmation of eligibility.

         10. Pregnant or nursing (lactating) women.

         11. Active autoimmune disease requiring systemic immunosuppressive treatment equivalent to
             ≥ 10mg daily of prednisone. Patients with autoimmune neurological diseases (such as MS
             or Parkinson's) will be excluded.

         12. Have any history of prior or active central nervous system (CNS) involvement (e.g.,
             leptomeningeal disease, parenchymal masses) with MTC. Screening for this (e.g., with
             lumbar puncture and/or brain MRI) is not required unless suspicious symptoms and/or
             radiographic findings are present. Subjects with calvarial metastatic disease that
             extends intracranially and involves the dura will be excluded, even if CSF is negative
             for MTC.

         13. Known seizure disorder or history of prior seizures requiring medication.

         14. History of allergy or hypersensitivity to study product excipients (human serum
             albumin, DMSO, and Dextran 40).