Ex Vivo T-Cell Depletion of Mobilized Peripheral Blood Stem Cells Via CD34-Selection (EXCESS)

November 26, 2025 updated by: Robert Krance, Baylor College of Medicine

Ex Vivo T-Cell Depletion of Mobilized Peripheral Blood Stem Cells Via CD34-Selection (EXCESS)

Participants are being asked to take part in this study because treatment of his or her disease requires a stem cell transplant. Stem cells or "mother" cells are the source of normal blood cells and lead to recovery of blood counts after bone marrow transplantation. Unfortunately, there is not a perfectly matched stem cell donor (like a sister or brother) for the participant and his or her disease does not permit enough time to identify another donor (like someone from a registry list that is not his or her relative) or another suitable donor has not been identified. However, a close relative of the patient has been identified whose stem cells are not a perfect match, but can be used.

Alternatively, the patient may have already received a stem cell transplant but have evidence of mixed chimerism, which means some of the patient's own bone marrow cells are present, rather than all of the donor's cells. This may lead to an increased risk of the disease coming back. Or, the patient may have all donor cells but his or her bone marrow is not working very well, which may lead to frequent blood or platelet (cells that help in clotting blood) transfusions or infection.

Regardless of the reason, it may be necessary to isolate stem cells from a haploidentical (half-match) donor in order to provide bone marrow function. Because the stem cells from the donor are only half-matched to the participant, the risk of graft-versus-host disease (GvHD) is very high. GvHD is a complication after transplant caused by donor T cells (graft) that attack the transplant recipient, and this complication can cause death after transplant. Thus, it is important that the donor's blood cells are treated to minimize cells that are most likely to attack the host's tissues. This is done by using a special device to capture the CD34+ stem cells from the donor's stem cell product prior to giving the cells to the host. This method minimizes the donor T cells, which are responsible for causing GvHD.

Purpose: In an effort to lower the occurrences and severity of graft-versus-host disease in patients and to lower the rate of transplant failure, investigators would like to specially treat the donor's blood cells to minimize the cells that are most likely to attack the patient's tissues.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Participation in this project will last approximately one year with follow-up exams.

Before treatment can begin, stem cells will be collected from the donor (a close relative) that has been selected as the best match for the participant. White blood cells will be collected from the donor. The cells will then be mixed with a special protein, called a CD34 antibody, that binds to the stem cells, which will then be separated out from the white blood cells by a special machine- called a CliniMACS CD34 Reagent System in the laboratory. This is an investigational device that is not approved by the FDA. Although this device is not approved for use in this country, it has been in use for years and is approved in other countries. The stem cells will be collected and given fresh or they can be frozen before they will be given to the participant.

On about days 28, 60, 100, 180 and 365 after the transplant, the participant will have the same tests/evaluations since the time of transplant. For patients who do not develop GvHD, they are not required to have these tests/evaluations.

In addition, for purposes of the study, health-related information will be collected for a year from the time of stem cell infusion. This will be used to determine survival, relapse, infections and GvHD that may occur following transplant.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
241

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • United States
    • Texas
      • Houston, Texas, United States, 77030
        • Recruiting
        • Houston Methodist Hospital
        • Contact:
        • Contact:
      • Houston, Texas, United States, 77030
        • Recruiting
        • Texas Children's Hospital
        • Contact:
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

No older than 66 years (Child, Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion criteria for Stem Cell Transplant WITH Conditioning (COHORT 1)

  1. Patient requiring allogeneic SCT
  2. Age between birth and 70 years
  3. Patient and/or responsible person able to understand and sign consent

Exclusion criteria for Stem Cell Transplant WITH Conditioning (COHORT 1)

  1. Active, acute GvHD > grade II or extensive, chronic GvHD
  2. Severe life, threatening infection
  3. Pulmonary dysfunction (FEV1, FVC or DLCO 40% of predicted or 3 SD below normal)
  4. Cardiac dysfunction (LVSF less than 25%)
  5. Psychiatric disturbance
  6. Lansky or Karnofsky score < 50%
  7. The presence of severe hepatic disease (direct bilirubin >3x upper limit of normal and AST > 5x upper limit of normal).
  8. Creatinine > 3x normal
  9. Known HIV Positivity
  10. Pregnancy

Inclusion Criteria for CD34+ Topoff WITHOUT conditioning (COHORT 2)

  1. Allogeneic SCT Recipient requiring additional cellular therapy
  2. Age between birth and 70 years
  3. Patient and/or responsible person able to understand and sign consent

  4. At least ONE of the following must be answered YES for a patient to be eligible to receive CD34+ topoff:

    1. Evidence of mixed chimerisms (less than 95% donor cells)
    2. Evidence of poor bone marrow function (bone marrow cellularity less than 50% with at least one cytopenia)
    3. Relapsed or persistent disease

Exclusion criteria for CD34+ Topoff WITHOUT conditioning (COHORT 2)

  1. Active, acute GvHD > grade II or extensive, chronic GvHD
  2. Severe life, threatening infection
  3. Known HIV positivity
  4. Pregnancy

Inclusion Criteria for CD34+ Topoff WITH conditioning (COHORT 3)

  1. Allogeneic SCT Recipient requiring additional cellular therapy
  2. Age between birth and 70 years
  3. Patient and/or responsible person able to understand and sign consent

  4. At least ONE of the following must be answered YES for a patient to be eligible to receive CD34+ topoff:

    1. Evidence of mixed chimerisms (less than 95% donor cells)
    2. Evidence of poor bone marrow function (bone marrow cellularity less than 50% with at least one cytopenia)
    3. Relapsed or persistent disease

Exclusion criteria for CD34+ Topoff WITH Conditioning (COHORT 3)

  1. Active, acute GVHD > grade II or extensive, chronic GvHD
  2. Severe life, threatening infection
  3. Pulmonary disfunction (FEV1, FVC or DLCO 40% of predicted or 3 SD below normal)
  4. Cardiac dysfunction (LVSF less than 25%)
  5. Psychiatric disturbance
  6. Lansky or Karnofsky score < 50%
  7. The presence of severe hepatic disease (direct bilirubin > 3x upper limit of normal and AST > 5x upper limit of normal)
  8. Creatinine > 3x normal
  9. Known HIV positivity
  10. Pregnancy

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Cohort 1: CD34+ Cells for transplant
Cohort 1 consists of patients receiving CD34+ selected peripheral blood stem cell transplant with a preceding conditioning regimen (chemotherapy with, or without, radiation). The stem cells will then be separated out from the white blood cells by a special machine- called a CliniMACS CD34 Reagent System in the laboratory.
Device: CliniMACS CD34 Reagent system
A special machine that separates out the donor cells that have been mixed with a special protein, CD34 antibody, that binds to the stem cells from the white blood cells.
Experimental: Cohort 2: CD34+ cells as a top off Without Conditioning
Cohort 2 consists of patients needing additional CD34+ stem cells collected by 'CliniMACS CD34 Reagent system' as a "topoff" without the need for additional conditioning prior to the infusion. These patients who have already received SCT and are receiving CD34+ cells from their original donor for poor graft function, declining chimerism or disease relapse.
Device: CliniMACS CD34 Reagent system
A special machine that separates out the donor cells that have been mixed with a special protein, CD34 antibody, that binds to the stem cells from the white blood cells.
Experimental: Cohort 3: CD34+ cells as a top off With Conditioning
Cohort 3 consists of patients needing additional CD34+ stem cells collected by 'CliniMACS CD 34+ Reagent System' as a "topoff" with the need for additional conditioning prior to the infusion. These patients who have already received SCT with conditioning and are receiving CD34+ cells from their original donor for poor graft function, declining chimerism or disease relapse.
Device: CliniMACS CD34 Reagent system
A special machine that separates out the donor cells that have been mixed with a special protein, CD34 antibody, that binds to the stem cells from the white blood cells.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
For Cohort 1: the rate of primary engraftment 50 days post SCT
Time Frame: 50 days
Primary engraftment is defined as achievement of absolute neutrophil count (ANC) is greater than or equal to 500/ul for three consecutive days by day 50 post transplant. The treatment regimen will be considered clinically useful if the primary engraftment rate is at least 85%.
50 days
For Cohort 2 (Without Conditioning) and Cohort 3 (With Conditioning): The total incidence of overall acute GvHD (greater than or equal to grade 3)
Time Frame: 100 days
The overall incidence of acute GvHD will be measured 100 days post stem cell transplant. The regimen will be considered acceptable if aGvHD greater than or equal to grade 3 rate is at least 10% or lower.
100 days

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Assessment of Long Term Survival
Time Frame: 1 year
Long term survival of recipients of G-CSF mobilized peripheral blood stem cells depleted of T cells by positive selection for the CD34+ antigen
1 year

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Baylor College of Medicine

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
The Methodist Hospital Research Institute
Center for Cell and Gene Therapy, Baylor College of Medicine

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Robert Krance, MD, Baylor College of Medicine

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
October 1, 2010

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
October 1, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
November 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
August 25, 2010

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 25, 2010

First Posted (Estimated)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
August 27, 2010

Study Record Updates

Last Update Posted (Estimated)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
December 3, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 26, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
November 1, 2025

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • H-27251 EXCESS
  • EXCESS (Other Identifier: Baylor College of Medicine)

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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