This study is designed as a single arm open label traditional Phase I, 3+3, study of CD4-redirected chimeric antigen receptor engineered T-cells (CD4CAR) in subjects with relapsed or refractory AML. The study will evaluate safety in this subject population and also the presence of efficacy signal described by elimination of residual disease to qualify subjects for stem cell transplant.

The study will be performed as a dose-escalation protocol. The investigators expect to recruit 20 subjects at Indiana University with an expected dropout rate of 25% primarily due to rapid progression or death and screen and or manufacturing failure. Taking this into account, the investigators expect to treat 15 subjects. The study will utilize autologous CD4CAR T-cells that are engineered to express a chimeric antigen receptor (CAR) targeting CD4 that is linked to the cluster of differentiation 28 (CD28), 4-1BB, cluster of differentiation 3-zeta (CD3ζ) signaling chains (third generation CAR). about 70% of AML with monocytic differentiation and 37% of all the rest express CD4 on their blasts.

At entry, disease status will be assessed. Qualifying subjects will be leukapheresed to obtain large numbers of peripheral blood mononuclear cells (PBMC) for the manufacturing. Then, participants will receive conditioning chemotherapy. Next, participants will receive CD4CAR cells by infusion on Day 0 of treatment. (The initial dose for this trial will be the highest dose level that was deemed safe from our other ongoing trials by the time this trial is ready to accrue).

If the disease progresses during the manufacturing period participants may be excluded from the study or an attempt to bridge for disease control will be offered. Minimal chemotherapy to keep the disease under control in the meanwhile is allowed if deemed necessary by investigators.

A single dose of CD4CAR transduced T cells will consist of the cell number for the dose level to be infused.

Post-infusion monitoring of CD4CAR T-cells: Subjects will have blood drawn for cytokine levels, CD4CAR Transgene Copy Number (PCR) and flow cytometry in order to evaluate the presence of CD4CAR cells on days 0, 1, 3, 5, 7, 14, and 28 following infusion (or as clinically needed). Cytokines levels will be evaluated per schedule above in addition to and as needed every 8 +/- 2 hours as feasible if/when Cytokine Release Syndrome, CRS, occurs and until resolution. Active monitoring of fungal and viral infections during treatment while utilizing standard prophylaxis recommended for HIV-positive subjects with T-cell aplasia and those undergoing allogeneic stem cell transplant. Investigators plan to collect data about clinicoradiologic measurements of residual tumor burden starting on day 7 and weekly afterward until Day 28 and then monthly for 6 months. This will be followed by quarterly clinical evaluations for the next two (2) years with a medical history, physical examination, and comprehensive blood testing. After these short- and intermediate-term evaluations are performed, these subjects will enter a rollover study to assess for disease-free survival (DFS), relapse, and the development of other health problems or malignancies where follow-up will be up to twice a year by phone and a questionnaire for an additional thirteen (13) years. The treating physician will decide to proceed with allogeneic or autologous transplant when needed.

Dose of CD4CAR description: the main objective of this study is to establish a recommended dose and/or schedule of CD4CAR. The guiding principle for dose escalation in phase I is to avoid unnecessary exposure of subjects to sub-therapeutic doses (i.e., to treat as many subjects as possible within the therapeutic dose range) while preserving safety and maintaining rapid accrual. Investigators will use the rule-based traditional Phase I "3+3" design for the evaluation of safety. Based on lab experience in mice the starting dose (dose level 1) for the first cohort of three subjects in phase I portion of the study will be 8x10^5 cells. The dose escalation or de-escalation will follow a modified Fibonacci sequence as below.

If more than one subject out of the first cohort of three subjects in dose level 1 experience dose limiting toxicity (DLT), the trial will be placed on hold. If zero or one out of three subjects in the first cohort of dose level 1 experience DLT, three more subjects will be enrolled at dose level 1; the dose escalation continues until at least two subjects among a cohort of six subjects experience DLT (i.e., ≥33% of subjects with a DLT at this dose level)

If one of the first three subjects in dose level 1 experiences a DLT, three more subjects will be treated at dose level 1.

If none of the three subjects or only one of the 6 subjects in the dose level 1 experiences a DLT, the dose escalation continues to the dose level 2 If one of the first three subjects in dose level 2 experience a DLT, three more subjects will be treated at dose level 2 If none of the three subjects or only one of the 6 subjects in the dose level2 experiences a DLT, the dose escalation continues to the dose level 3 If one of the first three subjects in dose level 3 experiences a DLT, three more subjects will be treated at dose level 3 If none of the three subjects or only one of the 6 subjects in the dose level 3 experiences a DLT, dose level 3 will be declared the maximum tolerated dose (MTD) and will be used as the recommended phase II dose (RP2D) for the phase II portion of the study.

In summary, the dose escalation continues until at least two subjects among a cohort of six subjects experience DLT (i.e., ≥33% of subjects with a DLT at that dose level). The recommended dose for phase II trials is defined as one dose level below this toxic dose level. Since some grade 3 and possibly 4 toxicities are highly likely to be reversible, grade 3 infectious, hematological and vascular toxicities will not be considered DLTs mandating dose reduction. Also allergic or infusion-related reactions ≤ grade 3 will not be counted as DLTs. There will be no intra-subject dose escalation or reduction.

To allow for full spectrum toxicity duration evaluation and reporting, no subjects within the same or a different cohort will be initiated on lymphodepleting chemotherapy sooner than 28 days from the initiation date of the preceding subject.

Inclusion Criteria:

1. ≥ 12 years old at the time of informed consent

2. Ability to provide written informed consent and HIPAA authorization.

3. Diagnosis of AML that is CD4+ and must have failed standard induction/ first line treatment such as intensive induction or less intensive hypomethylation and venetoclax first line. In the specific case of azacitidine and venetoclax (aza/ven), BM biopsy for response assessment on days 21-28 of first cycle. If disease progression by increasing number of blasts is documented, subject will be eligible. If no morphologic remission (persistent BM blasts above 5%) but evidence of efficacy exists, a second cycle without interruption will be given with the goal of achieving morphologic remission and repeat BM biopsy on days 21-28 of this cycle. If residual disease or disease progression is captured, then they will be considered refractory and will qualify for this trial. This is unless the subject now qualifies for a more intensive induction therapy that they did not qualify for when aza/ven was initially chosen as first-line treatment. Given the low response rate for aza/ven in the RR-AML, CR of only 13%, this combination would not be a prerequisite to qualify for the study.

   Note: If these subjects who fail first line treatment have an FDA approved treatment options available (including targeted and non-targeted treatment) for a second line treatment, they do not qualify for the trial until they also are deemed nonresponsive to those. If an approved second line is not available, subjects will be eligible after first line failure.

4. Creatinine clearance of > 60ml/min (or otherwise non clinically significant, per study investigator)

5. alanine aminotransferase/ aspartate aminotransferase ALT/AST < 3 x ULN

6. Bilirubin < 2 x ULN (UPPER LIMIT OF NORMAL)

7. No supplemental oxygen at rest Note: Pulmonary Function Test (PFT) only required per treating physician discretion

8. Adequate cardiac function with EJECTION FRACTION, EF, of ≥50%

9. Adequate venous access for apheresis and no other contraindications for leukapheresis Note: Adequate venous access means either sufficient access to a peripheral vein for collection or if venous access is insufficient for standard access, subject must have the ability to receive a temporary central venous catheter to establish venous access for apheresis.

   Note: Any treatment being given prior to leukapheresis must be stopped at least 2-3 weeks prior to leukapheresis.

10. Confirmation of a bone marrow donor for post CD4CAR transplant to proceed to transplant if eligible post treatment.

Exclusion Criteria:

1. CD4 negative AML

2. Pregnant or lactating women. The safety of this therapy on unborn children is not known. Female study participants of reproductive potential (see definition below) must have a negative serum or urine pregnancy test prior to initiation of conditioning chemotherapy, per research sites' clinical policy.

3. Uncontrolled active infection necessitating systemic therapy.

4. Active hepatitis B hb, or hepatitis C, HC, infection. Active hepatitis C is defined as the hepatitis C antibody is positive while quantitative HCV RNA results exceed the lower detection limit.

   Note the following subjects will be eligible:

   • Subjects with a history of hepatitis B but have received antiviral therapy and have non-detectable viral DNA for 6 months prior to enrollment are eligible.
   • Subjects seropositive for HBS antibodies due to hepatitis B virus vaccine with no signs or active infection (Negative HBs Ag, HBc and HBe Ags) are eligible.
   • Subjects who had hepatitis C but have received antiviral therapy and show no detectable hepatitis C virus (HCV) viral RNA for 6 months are eligible.
   • If hepatitis C antibody test is positive, then subjects must be tested for the presence of antigen by reverse transcription-polymerase chain reaction (RT-PCR) and be hepatitis C virus ribonucleic acid (HCV RNA) negative.

5. Concurrent use of systemic glucocorticoids in greater than replacement doses or steroid dependency defined in rheumatological and pulmonary diseases as uninterrupted corticosteroid intake for more than a year at a dosage of 0.3 mg/kg/day or greater, and where the underlying disease worsens on temporary stoppage of steroid therapy, with symptoms of steroids withdrawal (e.g., lethargy, headache, weakness, pseudo rheumatism, emotional disturbances, etc) precipitated by the temporary stoppage unless tapering can occur safely without compromising the underlying disease, the withdrawal tolerance and can happen in a timeframe appropriate to enroll in this trial without safety concerns

   Subjects who receive daily corticosteroids in replacement doses can be included in the study. The replacement doses are defined as following:

   1. Hydrocortisone 25mg/day or less
   2. Prednisone 10mg/day or less
   3. Dexamethasone 4mg or less Note: Recent or current use of inhaled glucocorticoids is not exclusionary, as this route pertains extremely minimal systemic penetration

6. Any uncontrolled active medical disorder that would preclude participation as outlined in the opinion of the treating investigator and/or Principal Investigator

7. HIV infection

8. Subjects who have received or will receive live vaccines within 30 days before the first experimental cell treatment. Inactivated seasonal flu vaccination is allowed.

9. Subjects with active autoimmune diseases who need systematic treatments (such as disease modifying agents, corticosteroids, and immunosuppressive drugs) during the last year.

   Note: Replacement therapy (thyroxine, insulin, or physiological corticosteroid replacement therapy (up to10 mg of oral daily prednisone or equivalent in hydrocortisone and dexamethasone) to treat adrenal dysfunction or pituitary dysfunction) is not considered as systematic therapy. Subjects who need inhalation corticosteroid therapy can be included in this trial. Subjects with vitiligo or in long-term remission of pediatric asthma or allergic diseases can be included in this trial.

10. Subjects with a history of mental disorders or drug abuse that may influence treatment compliance.

11. Active malignancy not related to AML that has required therapy in the last 3 years or is not in complete remission. Exceptions to this criterion include successfully treated non-metastatic basal cell or squamous cell skin carcinoma, or prostate cancer that does not require therapy. Other similar malignant conditions may be discussed with and permitted by the Principal Investigator.

12. Treatment with any investigational cell/gene therapy within the past 6 months

13. Treatment with any investigational anticancer agent within the past 14 days of study entry or 5 half-lives (whichever is shorter).

Eligibility for Conditioning Chemotherapy:

1. Specific organ function criteria for cardiac, renal, and liver function must be similar to initial inclusion values.
2. Review of co-morbidities to confirm no major changes in health status (examples of major changes include heart attack, stroke, and any major trauma).
3. Planned infusion does was successfully manufactured and met release criteria.
4. Negative pregnancy testing (if applicable).

Eligibility for CD4CAR infusion:

1. Afebrile and not receiving antipyretics, and no evidence of active infection per PI discretion. If fever is attributed to underlying disease, it will not disqualify.

2. Specific organ function criteria for cardiac, renal, and liver function must be similar to initial inclusion values. The following tests does not need repeated: EF if within 6 weeks of screening assessment.

   Note: Subjects may require a repeat PFT prior to CD4CAR infusion as determined by the treating physician in the following possible cases:

   • Subject develops a respiratory infection that results in significant changes in lung imaging from baseline
   • Subject's oxygenation from daily activities is compromised at baseline; or there is a significant change in oxygenation or lung imaging from baseline

3. If previous history of corticosteroid chemotherapy, subject must be off all but adrenal replacement doses 3 days before the CD4CAR infusion.

Exclusion Criteria:

Note: A subject may still receive the CD4CAR infusion up to 10 days post conditioning chemotherapy as long as they do not meet any of the following at time of infusion:

1. Requirement for supplemental oxygen to keep saturation greater than 95% or presence of radiographic abnormalities on a clinically indicated chest x-ray that are progressive.
2. New cardiac arrhythmia not controlled with medical management.
3. Hypotension requiring pressor support.
4. Positive blood cultures for bacteria, fungus, or virus within 48-hours of T cell infusion.