A Phase 1/2 interventional study of Siplizumab and Exchange Transfusion in Anemia, Sickle Cell, sponsored by Columbia University. Terminated at 1 site in United States. Open to participants aged 18 Years to 50 Years. Per ClinicalTrials.gov, last updated 2026-06-10.
Sponsored by Columbia University · Phase 1/2, Interventional, and Treatment
The purpose of this study is to find out whether siplizumab is safe and effective for patients with SCD undergoing an allogeneic transplant and to prevent development of Graft versus Host Disease (GVHD) and graft failure. The main goals of this study are :
In this study, participants will receive 5 infusions of the study drug, siplizumab, while getting a stem cell transplant for SCD. Before siplizumab infusion, participants will be given medications to reduce the risks of allergic reaction to the drug.
Phase I/II label single arm safety assessment study of Siplizumab-based conditioning. It is designed to determine the safety and feasibility of hematopoietic stem cell transplantation for patients with advanced sickle cell disease using in vivo T cell depletion with Siplizumab.
It is a three-stage design with a target sample size of at most 18 patients. At the first stage, a total of 6 patients will be recruited, the study will be stopped, if 2 or more of patients experience any of the following events: graft failure/Grade 3-4 acute GVHD/death in the first 100 days. If not, the study will proceed to the second stage and recruit additional 6 patients. The study will be stopped if 4 or more patients experience an event as specified above among the 12 patients. If not, the study will proceed to the third stage and recruit additional 6 patients, the study will be stopped any time if 6 or more patients experience an event among the 18 patients. The study will be stopped at any time if a patient death occurs.
1,134 studies on the registry are indexed under Anemia, Sickle Cell; 238 are open to participants now.
This study's enrollment of 1 is below the median of 40 across 769 interventional studies indexed under Anemia, Sickle Cell.
Browse Anemia, Sickle Cell studies →Columbia University is the lead sponsor of 1,136 studies on the registry; 195 are open to participants now.
Of its 180 completed or terminated interventional studies of FDA-regulated products, 148 (82%) have results posted.
Counted across the registry records on this site, refreshed daily.
Recipient Inclusion Criteria:
Patients with sickle cell anemia ( SS, Sβ0 thalassemia or severe SC) who are 18 - 50 years of age inclusive AND who have 1 or more of the following:
Adequate organ functions as defined as:
Patient must have a matched-or mismatched unrelated donor or mismatched related family donor.
Recipient Exclusion Criteria:
Donor Eligibility and Selection Criteria
Please note, donor selection will follow our institutional standard operating procedure (SOP). Key criteria are summarized below for convenience:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
A 0–100 scale of how well someone can carry out everyday activities. 100 is no complaints and no signs of illness; 70 is able to look after yourself but not to work or keep up normal activity; 50 is needing considerable help and frequent medical care.
Studies often ask for 60 or 70 and above. Your doctor gives the score.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECOG performance status
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
LVEF (left ventricular ejection fraction)
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Biopsy and archival tissue
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Karnofsky performance status (KPS)
A 0–100 scale of how well someone can carry out everyday activities. 100 is no complaints and no signs of illness; 70 is able to look after yourself but not to work or keep up normal activity; 50 is needing considerable help and frequent medical care.
Studies often ask for 60 or 70 and above. Your doctor gives the score.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Allogeneic and autologous transplant
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive 5 infusions of siplizumab. The first dose is given 14 days prior to the infusion of stem cells; the second dose is given 6 days before infusion; and doses 3, 4, and 5 are given on the day before, day of, and day after stem cell infusion.
Drug: Siplizumab · Procedure: Exchange Transfusion · Procedure: Total Body Irradiation · Procedure: Stem Cell Infusion · Drug: Cyclophosphamide 50mg · Drug: Mesna · Drug: Sirolimus Oral Tablet · Drug: Rituximab or Biosimilar
Premedication with diphenhydramine 50 mg PO is to be given 1 hour prior to siplizumab infusion. Premedication with hydrocortisone succinate 100 mg IV infused over 30 minutes and acetaminophen 650 mg PO are to be given at least 30 minutes prior to siplizumab infusion. Siplizumab 4.8 mg/kg total is given on Day -14 and 0.6mg/kg is given on days -6, -1, 0, and +1. It will be given as an IV infusion over 1 hour.
Also known as: TCD601 (Siplizumab)
Patient will undergo a red blood cell exchange transfusion to achieve a Hemoglobin S (HgbS) level \< 20% prior to starting therapy to prevent the development of a vaso-occlusive Crisis (VOC).
Radiation dose is 2Gy (Gy is a radiation unit of measurement). Radiation source and dose rates will be according to institutional practice. Total Body Irradiation (TBI) may be delivered from either linear accelerator or Cobalt sources.
Also known as: TBI
Standard institutional procedures should be followed for the processing and administration of stem cell products for infusion. The infused graft under no circumstances is to be irradiated. No in-line leukocyte filter should be used and no medications or fluids should be given piggyback through the catheter lumen used for infusion of stem cells. Vital signs should be monitored before beginning the infusion and periodically during administration and in accordance with institutional guidelines. Pre-medications prior to the graft infusion will be according to the institutions standard practice. Benadryl, epinephrine, hydrocortisone, and oxygen be available at the bedside, as well as an emergency medical code cart available in the vicinity of the patient, for emergency use in case of an infusion reaction.
Cyclophosphamide will be given on days +3 and +4 at a dose of 50 mg/kg. Hydration prior to cyclophosphamide should be given according to standard institutional practice. Day +3 dose should occur between 60 and 72 hours after graft infusion and day +4 post-transplant should occur approximately 24 hours after prior dose. Cyclophosphamide will be given as an IV infusion over 1-2 hours depending on volume or as per institutional standard practice. Cyclophosphamide will be dosed according to adjusted ideal body weight (AIBW) in patients weighing \> 125% ideal body weight (IBW).
Also known as: Cytoxan, Cytoxan Lyophilized
Mesna is to be given starting 1 hour prior to cyclophosphamide at the same dose (50 mg/kg) as a continuous infusion over 24 hours.
Also known as: Mesnex
Sirolimus will be given orally with a loading dose of 12 mg, then followed by 4 mg orally daily. Dosage will be adjusted to a therapeutic target of 10 - 15ng/ml in first 3 months post transplant and 3-10 after 3 months. Sirolimus should be started on day +5. It will be continued until at least day 180. Sirolimus can be tapered or continued according to the treating physician discretion and the presence of absence of GVHD and/or degree of donor chimerism. Sirolimus should be continued if donor chimerism is less than 50% to prevent graft loss.
Also known as: Rapamycin, Rapamune
Rituximab (375 mg/m2/dose) will be administered on Days -14 and -6. In those subjects receiving ongoing renal replacement therapy, rituximab should be administered several hours after hemodialysis. The first rituximab solution for infusion should be administered intravenously at an initial rate of 50 milligrams/hour (mg/hr). The rate may be escalated by 50mg/hr every 30 minutes to a maximum of 400 mg/hr. Subsequent infusions may be started at 100 milligrams/hour (mg/hr) and titrated by 100 mg/hr every 30 minutes to a maximum of 400mg/hr if the subject tolerated the first infusion.
Also known as: Riabni, Rituxan, Ruxience, Truxima
Failure Rate
Failure rate is a safety endpoint. Failure rate is defined as: graft failure (Primary Graft Rejection: Primary graft rejection is defined as the absence of donor cells (% donor cells \< 5%) assessed by bone marrow or peripheral blood chimerism assays by Day 42. Late Graft Rejection: The absence (\<5%) of donor hematopoietic cells in peripheral blood or bone marrow beyond Day 42 in a patient who had initial evidence of hematopoietic recovery with \> 20% donor cells will be considered a late graft rejection.); or grades III-IV GVHD (as assessed by Center for International Blood and Marrow Transplant Research (CIBMTR) and NIH Consensus Criteria); or death at 100 days.
Time frame: 12 Months Post Stem Cell Transplant
Time to Engraftment
Time to neutrophil engraftment is defined as the first of 3 measurements on consecutive days when the patient has an absolute neutrophil count of 500/μL after conditioning. Time to platelet engraftment will be defined as the first day of a minimum of 3 measurements on different days that the patient has achieved a platelet count \> 50,000/μL AND did not receive a platelet transfusion in the previous 7 days. Time to red cell engraftment is defined as the first of two measurements on different days that the patient has achieved an absolute reticulocyte count \> 30,000/μL following conditioning regimen induced nadir.
Time frame: Day 100
Incidence of GVHD of Any Grade
Incidence of acute and chronic GVHD of any grade as evaluated according to the CIBMTR and NIH criteria respectively.
Time frame: 12 Months Post Stem Cell Transplant
Incidence of Other Transplant Related Toxicities
Incidence of other transplant related toxicities, including Veno-occlusive disease (VOD), Idiopathic pneumonia syndrome (IPS), Central nervous system (CNS) toxicity, or Posterior reversible encephalopathy syndrome (PRES).
Time frame: 12 Months Post Stem Cell Transplant
Incidence of Significant Transplant-related Infections
Significant infections will be recorded including but not limited to bacterial or fungal sepsis, cytomegalovirus (CMV) reactivation with/without clinical disease, adenovirus infection, epstein-barr virus (EBV) reactivation with or without post-transplant lymphoproliferative disorders (PTLD), other significant viral reactivations or community-acquired viral infections and invasive mold infections.
Time frame: 12 Months Post Stem Cell Transplant
Number of Participants With Donor Chimerism >5%
Chimerism is a measure of the engraftment of donor cells within the recipient and is expressed as the percentage ratio between the number of donor cells and recipient cells. Chimerism will be determined by Short Tandem Repeat analysis.
Time frame: Day 30, Day 100, and 1 year
Percentage of Participants Who Achieve Immune Reconstitution
Peripheral blood quantitative assessment of the main lymphocyte subpopulations (CD3+, CD4+, CD8+, CD19+, and CD16+/56+). Lymphocytes will be assessed by flow cytometry. In addition, quantitative immunoglobulins will be measured for Immunoglobulin A (IgA), Immunoglobulin M (IgM) and Immunoglobulin (IgG). These will be performed at Day +60 (±10 days) as well as at 1 year (+/- 2 weeks) and after long term follow up at the discretion of the investigator. Descriptive statistics will be used to describe the percentage of patient who are able to achieve reconstitution of important lymphocyte subsets and B cell function at the defined timepoint above.
Time frame: 12 Months Post Stem Cell Transplant
| Milestone | Siplizumab |
|---|---|
| Started | 1 |
| Completed | 1 |
| Not completed | 0 |
Failure rate is a safety endpoint. Failure rate is defined as: graft failure (Primary Graft Rejection: Primary graft rejection is defined as the absence of donor cells (% donor cells \< 5%) assessed by bone marrow or peripheral blood chimerism assays by Day 42. Late Graft Rejection: The absence (\<5%) of donor hematopoietic cells in peripheral blood or bone marrow beyond Day 42 in a patient who had initial evidence of hematopoietic recovery with \> 20% donor cells will be considered a late graft rejection.); or grades III-IV GVHD (as assessed by Center for International Blood and Marrow Transplant Research (CIBMTR) and NIH Consensus Criteria); or death at 100 days.
No measurements were reported for this outcome.
Time to neutrophil engraftment is defined as the first of 3 measurements on consecutive days when the patient has an absolute neutrophil count of 500/μL after conditioning. Time to platelet engraftment will be defined as the first day of a minimum of 3 measurements on different days that the patient has achieved a platelet count \> 50,000/μL AND did not receive a platelet transfusion in the previous 7 days. Time to red cell engraftment is defined as the first of two measurements on different days that the patient has achieved an absolute reticulocyte count \> 30,000/μL following conditioning regimen induced nadir.
No measurements were reported for this outcome.
Incidence of acute and chronic GVHD of any grade as evaluated according to the CIBMTR and NIH criteria respectively.
No measurements were reported for this outcome.
Incidence of other transplant related toxicities, including Veno-occlusive disease (VOD), Idiopathic pneumonia syndrome (IPS), Central nervous system (CNS) toxicity, or Posterior reversible encephalopathy syndrome (PRES).
No measurements were reported for this outcome.
Significant infections will be recorded including but not limited to bacterial or fungal sepsis, cytomegalovirus (CMV) reactivation with/without clinical disease, adenovirus infection, epstein-barr virus (EBV) reactivation with or without post-transplant lymphoproliferative disorders (PTLD), other significant viral reactivations or community-acquired viral infections and invasive mold infections.
No measurements were reported for this outcome.
Chimerism is a measure of the engraftment of donor cells within the recipient and is expressed as the percentage ratio between the number of donor cells and recipient cells. Chimerism will be determined by Short Tandem Repeat analysis.
No measurements were reported for this outcome.
Peripheral blood quantitative assessment of the main lymphocyte subpopulations (CD3+, CD4+, CD8+, CD19+, and CD16+/56+). Lymphocytes will be assessed by flow cytometry. In addition, quantitative immunoglobulins will be measured for Immunoglobulin A (IgA), Immunoglobulin M (IgM) and Immunoglobulin (IgG). These will be performed at Day +60 (±10 days) as well as at 1 year (+/- 2 weeks) and after long term follow up at the discretion of the investigator. Descriptive statistics will be used to describe the percentage of patient who are able to achieve reconstitution of important lymphocyte subsets and B cell function at the defined timepoint above.
No measurements were reported for this outcome.
Collected over 2 years. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Siplizumab | — | — | — |
Data was not analyzed or disclosed in an effort to protect participant confidentiality (n=1).
| Age, Categorical | Siplizumab |
|---|---|
| <=18 years | — |
| Between 18 and 65 years | — |
| >=65 years | — |
| Sex: Female, Male | Siplizumab |
|---|---|
| Female | — |
| Male | — |
| Ethnicity (NIH/OMB) | Siplizumab |
|---|---|
| Hispanic or Latino | — |
| Not Hispanic or Latino | — |
| Unknown or Not Reported | — |
| Race (NIH/OMB) | Siplizumab |
|---|---|
| American Indian or Alaska Native | — |
| Asian | — |
| Native Hawaiian or Other Pacific Islander | — |
| Black or African American | — |
| White | — |
| More than one race | — |
| Unknown or Not Reported | — |
| Region of Enrollment(participants) | Siplizumab |
|---|
PDFs hosted by the registry, ClinicalTrials.gov.
Ran from Sep 2023 to primary completion in Dec 2024, 14 months.
Results were first posted in Feb 2026, 1 year 2 months after primary completion.
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This study is terminated, as verified in Jun 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Siplizumab