Protective conditioning for acute graft-versus-host disease

Area of Science:

• Hematopoietic stem cell transplantation
• Immunology
• Oncology

Background:

• Acute graft-versus-host disease (GVHD) is a major complication of hematopoietic-cell transplantation.
• Preclinical studies in mice demonstrated that conditioning with total lymphoid irradiation (TLI) plus antithymocyte serum protects against GVHD.
• This study evaluated the efficacy of TLI plus antithymocyte globulin (ATG) in human patients.

Purpose of the Study:

• To assess the safety and efficacy of a conditioning regimen using total lymphoid irradiation and antithymocyte globulin in patients undergoing hematopoietic-cell transplantation.
• To evaluate the impact of this conditioning on acute GVHD incidence.
• To investigate the graft antitumor effects and immune modulation in patients with lymphoid malignancies or acute leukemia.

Main Methods:

• Thirty-seven patients with lymphoid malignancies or acute leukemia received conditioning with 10 doses of TLI (80 cGy each) plus ATG.
• Patients then received infusions of HLA-matched peripheral-blood mononuclear cells from donors treated with granulocyte colony-stimulating factor.
• Immune responses, including T-cell cytokine production and alloantigen proliferation, were analyzed.

Main Results:

• Only 2 out of 37 patients developed acute GVHD, indicating a significant reduction in incidence.
• Patients with lymphoid malignancies showed potent antitumor effects, with some achieving complete remission.
• Conditioning with TLI plus ATG increased donor CD4+ T cell interleukin-4 production and reduced in vitro proliferative responses to alloantigens.

Conclusions:

• The conditioning regimen of total lymphoid irradiation plus antithymocyte globulin is effective in decreasing acute GVHD incidence after hematopoietic-cell transplantation.
• This strategy also supports graft antitumor activity in patients with lymphoid malignancies and acute leukemia.
• The regimen modulates immune responses, enhancing graft-versus-leukemia effects while mitigating GVHD.