Last reviewed 2026-04-23 · How we verify

Preparative regimen

A preparative regimen is a chemotherapy and/or radiation treatment protocol designed to condition the bone marrow and immune system before hematopoietic stem cell transplantation.

A preparative regimen is a chemotherapy and/or radiation treatment protocol designed to condition the bone marrow and immune system before hematopoietic stem cell transplantation. Used for Conditioning prior to hematopoietic stem cell transplantation for hematologic malignancies, Conditioning prior to hematopoietic stem cell transplantation for severe aplastic anemia, Conditioning prior to hematopoietic stem cell transplantation for inherited bone marrow failure syndromes.

At a glance

Mechanism of action

Preparative regimens use high-dose chemotherapy, radiation, or both to eliminate diseased bone marrow cells, suppress the recipient's immune system to prevent graft rejection, and create space for donor stem cells to engraft. The intensity and composition vary based on the underlying disease, donor type, and patient factors, ranging from myeloablative (fully ablative) to reduced-intensity conditioning regimens.

Approved indications

• Conditioning prior to hematopoietic stem cell transplantation for hematologic malignancies
• Conditioning prior to hematopoietic stem cell transplantation for severe aplastic anemia
• Conditioning prior to hematopoietic stem cell transplantation for inherited bone marrow failure syndromes

Common side effects

• Mucositis
• Myelosuppression
• Nausea and vomiting
• Graft-versus-host disease (GVHD)
• Infection
• Organ toxicity (hepatic, renal, cardiac, pulmonary)

Key clinical trials

• Administering Peripheral Blood Lymphocytes Transduced With a CD70-Binding Chimeric Antigen Receptor to People With CD70 Expressing Cancers (PHASE1, PHASE2)
• A Phase 2 Trial for Metastatic Melanoma Using Adoptive Cell Therapy With Tumor Infiltrating Lymphocytes Plus IL-2 Either Alone or Following the Administration of Pembrolizumab (PHASE2)
• Autologous T Cells Transduced With Retroviral Vectors Expressing TCRs for Participant-specific Neoantigens in Patients With Hematologic Malignancies (PHASE1)
• CD22 CAR T-cells to Extend Remission Following Commercial CD19 CAR T-cells in Children, Adolescents, and Adults With Relapsed/Refractory B-cell Acute Lymphoblastic Leukemia (PHASE2)
• MT2025-35 Allogeneic Hematopoietic Stem Cell Transplantation Using Reduced Intensity Conditioning Treosulfan and Fludarabine, With Post-Transplant Cytoxan (PTCy) for the Treatment of Hematological Diseases (PHASE2)
• Intensity-Modulated Radiation Therapy, Etoposide, and Cyclophosphamide Followed By Donor Stem Cell Transplant in Treating Patients With Relapsed or Refractory Acute Lymphoblastic Leukemia or Acute Myeloid Leukemia (PHASE1, PHASE2)
• T Cell Receptor Immunotherapy for Patients With Metastatic Non-Small Cell Lung Cancer (PHASE2)
• Administration of Autologous T-Cells Genetically Engineered to Express T-Cell Receptors Reactive Against Neoantigens in People With Metastatic Cancer (PHASE2)

Primary sources

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