Conditioning regimen

Conditioning Regimen

A conditioning regimen is a preparative treatment protocol used primarily in the context of hematopoietic stem cell transplantation (HSCT). The purpose of the conditioning regimen is to prepare the patient's body to receive the transplanted stem cells, which can be derived from bone marrow, peripheral blood stem cells, or umbilical cord blood.

Purpose

The conditioning regimen serves several critical functions:

1. Myeloablation: It destroys the patient's existing bone marrow to make space for the new stem cells to engraft and proliferate. 2. Immunosuppression: It suppresses the patient's immune system to prevent rejection of the transplanted cells. 3. Disease Eradication: In cases of hematologic malignancies, the regimen helps to eradicate residual cancer cells.

Types of Conditioning Regimens

Conditioning regimens can be classified into two main categories:

Myeloablative Conditioning (MAC)

This type of regimen involves high-dose chemotherapy and/or radiation therapy that completely destroys the bone marrow. It is typically used in younger patients or those with aggressive diseases. Common agents used include:

• Cyclophosphamide
• Busulfan
• Total body irradiation (TBI)

Reduced-Intensity Conditioning (RIC)

Also known as non-myeloablative conditioning, this regimen uses lower doses of chemotherapy and/or radiation. It is suitable for older patients or those with comorbidities. It relies more on the graft-versus-tumor effect for disease control. Agents used may include:

• Fludarabine
• Melphalan
• Low-dose TBI

Complications

Conditioning regimens can lead to several complications, including:

• Graft-versus-host disease (GVHD): A condition where the donor cells attack the recipient's tissues.
• Infections: Due to immunosuppression, patients are at increased risk of infections.
• Organ toxicity: High-dose chemotherapy and radiation can damage organs such as the liver, lungs, and heart.

Recent Advances

Research is ongoing to develop more targeted conditioning regimens that minimize toxicity while maximizing efficacy. Novel approaches include:

• Targeted radiotherapy: Using radio-labeled antibodies to deliver radiation directly to cancer cells.
• Monoclonal antibodies: Agents like rituximab are being explored to reduce the intensity of conditioning.

Also see

• Hematopoietic stem cell transplantation
• Graft-versus-host disease
• Chemotherapy
• Radiation therapy

Resources

Latest articles - Conditioning regimen

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Source: Data courtesy of the U.S. National Library of Medicine. Since the data might have changed, please query MeSH on Conditioning regimen for any updates.

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