Graft-versus-tumor effect

Immune response against tumor cells by transplanted immune cells

The graft-versus-tumor effect (GVT) is a beneficial immunological phenomenon that occurs following allogeneic hematopoietic stem cell transplantation (HSCT). It involves the recognition and destruction of tumor cells by the donor's immune cells, which are part of the graft. This effect is a critical component of the therapeutic success of allogeneic HSCT in treating certain types of cancer, particularly hematological malignancies.

Mechanism

The GVT effect is primarily mediated by donor T cells and natural killer cells that are transferred to the recipient during the transplantation process. These immune cells recognize and attack residual tumor cells in the recipient's body. The process involves several steps:

1. Antigen Recognition: Donor T cells recognize tumor-associated antigens presented by the recipient's antigen-presenting cells.
2. Activation and Proliferation: Upon recognition, donor T cells become activated and proliferate.
3. Cytotoxic Response: Activated T cells and natural killer cells exert cytotoxic effects on tumor cells through the release of cytokines and direct cell-to-cell contact.

Clinical Significance

The GVT effect is a double-edged sword. While it can lead to the eradication of tumor cells, it is closely related to the graft-versus-host disease (GVHD), a condition where donor immune cells attack the recipient's healthy tissues. Balancing the GVT effect and minimizing GVHD is a major challenge in allogeneic HSCT.

Applications

The GVT effect is particularly effective in treating:

• Acute myeloid leukemia (AML)
• Chronic myeloid leukemia (CML)
• Non-Hodgkin lymphoma
• Multiple myeloma

Strategies to Enhance GVT

Several strategies are being explored to enhance the GVT effect while minimizing GVHD:

• Donor Lymphocyte Infusion (DLI): Infusing additional donor lymphocytes after transplantation to boost the GVT effect.
• Cytokine Therapy: Using cytokines such as interleukin-2 to stimulate donor immune cells.
• Genetic Engineering: Modifying donor T cells to enhance their tumor-targeting capabilities.

Related pages

• Graft-versus-host disease
• Hematopoietic stem cell transplantation
• Immunotherapy
• Cancer treatment