Lymphodepletion is permissive to the development of spontaneous T-cell responses to the self-antigen PR1 early after allogeneic stem cell transplantation and in patients with acute myeloid leukemia undergoing WT1 peptide vaccination following chemotherapy.

PR1, an HLA-A*0201 epitope shared by proteinase-3 (PR3) and elastase (ELA2) proteins, is expressed in normal neutrophils and overexpressed in myeloid leukemias. PR1-specific T cells have been linked to graft-versus-leukemia (GVL) effect. We hypothesized that lymphopenia induced by chemo-radiotherapy can enhance weak autoimmune responses to self-antigens such as PR1. We measured PR1-specific responses in 27 patients 30-120 days following allogeneic stem cell transplant (SCT) and correlated these with ELA2 and PR3 expression and minimal residual disease (MRD). Post-SCT 10/13 CML, 6/9 ALL, and 4/5 solid tumor patients had PR1 responses correlating with PR3 and ELA2 expression. At day 180 post-SCT, 8/8 CML patients with PR1 responses were BCR-ABL-negative compared with 2/5 BCR-ABL-positive patients (P = 0.025). In contrast, PR1 responses were detected in 2/4 MRD-negative compared with 4/5 MRD-positive ALL patients (P = 0.76). To assess whether the lymphopenic milieu also exaggerates weak T-cell responses in the autologous setting, we measured spontaneous induction of PR1 responses in 3 AML patients vaccinated with WT1-126 peptide following lymphodepletion. In addition to WT1-specific T cells, we detected PR1-specific T cells in 2 patients during hematopoietic recovery. Our findings suggest that lymphopenia induced by chemo-radiotherapy enhances weak autoimmune responses to self-antigens, which may result in GVL if the leukemia expresses the relevant self-antigen.

Evolution of the donor T-cell repertoire in recipients in the second decade after allogeneic stem cell transplantation.

After allogeneic stem cell transplantation (SCT), T lymphocyte function is reestablished from the donor's postthymic T cells and through thymic T-cell neogenesis. The immune repertoire and its relation to that of the donor have not been characterized in detail in long-term adult SCT survivors. We studied 21 healthy patients in their second decade after a myeloablative SCT for hematologic malignancy (median follow-up, 12 years). Immune profiles were compared with donor samples cryopreserved at transplant and beyond 10 years from SCT. Only one recipient was on continuing immunosuppression. Compared with the donor at transplant, there was no significant difference in CD4, CD8, natural killer, and B-cell blood counts. However, compared with donors, recipients had significantly fewer naive T cells, lower T-cell receptor excision circle levels, fewer CD4 central memory cells, more effector CD8(+) cells, and more regulatory T cells. TCR repertoire analysis showed no significant difference in complexity of TCRVß spectratype between recipients and donors, although spectratype profiles had diverged with both gain and loss of donor repertoire peaks in the recipient. In conclusion, long-term allogeneic SCT survivors have subtle defects in their immune profile consistent with defective thymic function but compatible with normal health. This study is registered at http://www.clinicaltrials.gov as NCT00106925.

Favorable outcomes in patients surviving 5 or more years after allogeneic hematopoietic stem cell transplantation for hematologic malignancies.

Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for some hematologic malignancies. As the overall number of survivors continues to increase, studies systematically examining outcomes in long-term survivors are needed. We studied the clinical and quality-of-life outcomes in HSCT recipients surviving 5 or more years from HSCT. Since 1993, 262 patients with hematologic malignancies received a T cell-depleted myeloablative HSCT from an HLA-identical sibling at a single center. Ninety-two survived beyond 5 years from HSCT (median follow-up 9.4 years, range: 5.1-15.3). Median age at transplantation was 35 years (range: 10-56). Twenty-two (24%) received a bone marrow transplant, and 70 (76%) received a peripheral blood HSCT. Of the 92 survivors, 60 completed quality-of-life measures. The main outcomes examined were chronic graft-versus-host-disease, disease relapse, survival, health-related quality-of-life (HRQL) (Functional Assessment of Cancer Therapy-General), physical and mental health (SF-36), and symptom experience (Rotterdam Symptom Checklist). Seventy-five (82%) of 92 survivors no longer required systemic immunosuppressive treatment. Four (4.3%) relapsed with leukemia at a median of 8.5 years (range: 6.2-14.0) after HSCT. Four (4.3%) died between 7.4 and 13.4 years post-HSCT (1 relapse, 1 lung cancer, 1 pneumonia, 1 brain hemorrhage). Most survivors beyond 5 years had an excellent performance status with no difference in physical and mental health and higher HRQL scores (P = .02) compared with population norms. Although physical and psychologic symptom distress was low, those with higher symptom distress experienced inferior HRQL. These results show that 5 or more years after T cell-depleted HSCT for hematologic malignancy most individuals survive disease free with an excellent performance status, preserved physical and psychological health, and excellent HRQL.