Recruiting
Phase 1
Phase 2

Mixed Chimerism

Sponsor:

Massachusetts General Hospital

Code:

NCT05900401

Conditions

Kidney Failure

Kidney Transplant; Complications

Chimera

Eligibility Criteria

Sex: All

Age: 18 - 65

Healthy Volunteers: Not accepted

Interventions

Bone Marrow Transplant

Peripheral Blood Stem Cell Collection

Fludarabine

Cyclophosphamide

Rituximab

Study Details

Brief summary:

This study will examine the safety and effectiveness of a bone marrow transplant after kidney transplant (from either a living or deceased donor). An investigational medication and other treatments will be given prior to and after the transplant to help protect the transplanted kidney from being attacked by the body's immune system

Conditions

Kidney Failure

Kidney Transplant; Complications

Chimera

Study ID

NCT05900401

Start date

Oct 1, 2023

Status verified date

Sep, 2026

Completion date

Dec, 2032

Anticipated

Primary completion date

Dec, 2031

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 65

Healthy Volunteers: Not accepted

Recipient Inclusion Criteria

1. Male or female 18-65 years of age.
2. Kidney transplant recipients from either LD or DD, with cryo-preserved HSCs available, good renal function (GFR>60 ml/min/1.73m2), normal current allograft biopsy, and no history of documented rejection episodes.
3. First or second renal transplant.
4. Use of FDA-approved methods of contraception (those with less than a 3% failure rate) by all recipients from the time that study treatment begins until 104 weeks (24 months) after renal transplantation. (For further information on FDA- approved methods of contraception, see https://www.fda.gov/media/150299/download
5. Ability to understand and provide informed consent.
6. Negative COVID-19 test during screening and two days prior to HSC transplantation (HSCT).

Deceased Donor (DD)

1. Male or female 18-70 years of age.
2. Consent to donate vertebral bones is obtained from the donor family.
3. HSCs are successfully cryopreserved and saved >2X106/kg (CD34+ cells) of the recipient.
4. Acceptable laboratory parameters (hematology in normal or near-normal range. Liver function <2 times the upper limit of normal, and normal creatinine)
5. Negative for viral infection with HbsAg, HIV, HCV, or HTLV-1
6. Negative COVID-19 test at the time of HSC procurement.

Living Donor (LD)

1. Willingness to provide HSCs by leukapheresis or bone marrow aspiration.
2. Negative serologic pregnancy test for females of childbearing potential
3. Good general health as per conventional evaluation for kidney donation.
4. Acceptable laboratory parameters (hematology in normal or near normal range. Liver function <2 times the upper limit of normal, and normal creatinine)
5. Negative for viral infection with HbsAg, HIV, HCV, or HTLV-1.
6. Cardiac/pulmonary function within normal limits (CXR, ECG).
7. Ability to understand and provide informed consent.
8. Meets standard institutional criteria for PBSC collection.
9. Negative COVID-19 test during screening and two days prior to PBSC collection.

Recipient Exclusion Criteria

1. ABO blood group-incompatible renal allograft.
2. Evidence of anti-HLA antibody (donor specific with an MFI >1000) as assessed by routine methodology (Luminex)
3. Previous history of biopsy proven rejection.
4. Persistent Leukopenia (WBC less than 2,000/mm3) or thrombocytopenia (<100,000/mm3).
5. Seropositivity for HIV-1, hepatitis B surface or core antigen, or hepatitis C virus (confirmed by hepatitis C virus RNA).
6. Active infection
7. Left ventricular ejection fraction < 40% as determined by TTE or clinical evidence of heart failure.
8. Forced expiratory volume FEV1 or DLCO < 50% of predicted.
9. Lactation or pregnancy.
10. History of cancer (following the American Transplant Society Guidelines)
11. Underlying renal disease etiology with high risk of disease recurrence in the transplanted kidney (such as focal segmental glomerulosclerosis). Autoimmune diseases such as Lupus and Thrombotic Thrombocytopenic Purpura.
12. Enrollment in other investigational drug studies within 30 days prior to enrollment.
13. Abnormal (>2 times lab normal) values for (a) liver function chemistries (ALT, AST, AP), (b) bilirubin, (c) coagulation studies (PT, PTT), or any patients on chronic anticoagulation therapy.
14. Allergy or sensitivity to any component of Siplizumab, fludarabine, CP, tacrolimus, MMF or rituximab.
15. Any medical condition that the investigator deems incompatible with participation in the trial. This includes a history of alcohol abuse or illicit drug use/dependence.
16. Non-insulin dependent diabetes (NIDDM) without good blood glucose control (HbA1c<7). Severe retinopathy, gastroparesis, or severe neuropathy which prevent subject's normal independent daily activities.

Study Design

Enrollment

20 participants

Anticipated

Allocation

Non randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: Kidney and Stem Cell Recipients

Months-Years after standard transplant, patients will undergo bone marrow transplant (either from prospective collection of stem cells from their living donor, or from bone marrow collected at the time of deceased donation)

experimental: Kidney and Stem Cell Donors

PBSC will be collected from the LD via leukapheresis 1-4 weeks before the scheduled HSCT. The donor will first undergo standard GCSF mobilization: GCSF (can be TBO-GCSF) dosed at 10 mcg/kg/d (rounded to nearest pre-filled syringe) administered subcutaneously daily for 5 consecutive days. On the 5th day, the donor will undergo standard large volume leukapheresis. The target yield will be 2-3 x 106 CD34+ cells / kg of actual recipient body weight. A maximum of 3 days of pheresis will be allowed. A minimum of 2 x 106 CD34+ cells / kg of actual recipient body weight will be required to proceed

Interventions

Bone Marrow Transplant

Months-Years after standard transplant, patients will undergo bone marrow transplant (either from prospective collection of stem cells from their living donor, or from bone marrow collected at the time of deceased donation)

Peripheral Blood Stem Cell Collection

PBSC will be collected from the LD via leukapheresis 1-4 weeks before the scheduled HSCT. The donor will first undergo standard GCSF mobilization: GCSF (can be TBO-GCSF) dosed at 10 mcg/kg/d (rounded to nearest pre-filled syringe) administered subcutaneously daily for 5 consecutive days. On the 5th day, the donor will undergo standard large volume leukapheresis. The target yield will be 2-3 x 106 CD34+ cells / kg of actual recipient body weight. A maximum of 3 days of pheresis will be allowed. A minimum of 2 x 106 CD34+ cells / kg of actual recipient body weight will be required to proceed.

Fludarabine

Fludarabine 15 mg/m2/day on days -5 to -3 (3 doses)

Cyclophosphamide

Cyclophosphamide (CP) 30 mg/kg/day on days -5 and -4

Rituximab

Rituximab on study day -6

Siplizumab

Siplizumab (anti-CD2 mAb) on days, -2, -1, 0 and +1.

Primary outcome measure

  • Incidence of transient mixed chimerism [ Time Frame: 3 months ]
  • Incidence of renal allograft tolerance [ Time Frame: 2 years after immunosuppression withdrawal ]

Central Contacts and Locations

Central contacts

Locations

Massachusetts General Hospital

Recruiting

Boston, Massachusetts, United States, 02114

Contacts

Principal Investigator:

Tatsuo Kawai, MD, PhD

More Information

Sponsor

Massachusetts General Hospital

Last update posted

Sep 28, 2026

Last verified

Sep, 2026

Keywords

  • Tolerance
  • Transplant

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-29. This information was provided to ClinicalTrials.gov by Massachusetts General Hospital on 2026-09-28. Recruitment status is synced daily from ClinicalTrials.gov and may not reflect the sponsor's current status. Confirm during your call.