Robert Q. Le

Repeated PR1 and WT1 peptide vaccination in Montanide-adjuvant fails to induce sustained high-avidity, epitope-specific CD8+ T cells in myeloid malignancies

Background We previously showed that vaccination with one dose of PR1 and WT1 peptides induces transient anti-leukemia immunity. We hypothesized that maintenance of a sustained anti-leukemia response may require frequent boost injections. Design and Methods Eight patients with myeloid malignancies were enrolled in this phase II study, and 6 completed 6 injections of PR1 and WT1 peptides in Montanide-adjuvant with GM-CSF, every two weeks. Results Both high- and low-avidity PR1 or WT1-specific CD8+ T cells were detected in all evaluable patients after the first vaccine dose. Repeated vaccination led to selective deletion of high avidity PR1- and WT1-specific CD8+ T cells and was not associated with significant reduction in WT1-expression. Additional boosting failed to increase vaccine-induced CD8+ T-cell frequencies further and in all patients the response was lost before the 6th dose. PR1- or WT1-specific CD8+ T cells were not detected in bone marrow samples, excluding their preferential localization to this site. Following a booster injection three months after the 6th vaccine dose, no high-avidity PR1 or WT1-specific CD8+ T cells could be detected, whereas low-avidity T cells were readily expanded. Conclusions These data support the immunogenicity of PR1 and WT1 peptide vaccines. However, repeated delivery of peptides with Montanide-adjuvant and GM-CSF leads to rapid loss of high-avidity peptide-specific CD8+ T cells. These results may offer an explanation for the lack of correlation between immune and clinical responses observed in a number of clinical trials of peptide vaccination. New approaches are needed to induce long-term high-avidity memory responses against leukemia antigens. (ClinicalTrials.gov Identifier: NCT00499772)

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.

Male survivors of allogeneic hematopoietic stem cell transplantation have a long term persisting risk of cardiovascular events

Long-term survivors of allogeneic stem cell transplantation (SCT) have increased risk of cardiovascular disease. We retrospectively studied cardiovascular risk factors (CVRFs) in 109 SCT survivors (62 males, 47 females; median age 34 years) five years or more after bone marrow (15) or T cell-depleted peripheral blood (94) SCT for CML (56), acute leukemia (29), MDS (13), and others (11). One death and two cardiovascular events were reported. At five and ten years after SCT, respectively, 44% and 52% had abnormal lipid profiles; 23% of 5-year survivors met the Adult Treatment Panel III threshold for dyslipidemia treatment, which is substantially higher than the age-matched general population. There were significant increases in prevalence of hypertension (p < 0.001), diabetes (p = 0.018), and body mass index (p = 0.044) after SCT compared with baseline. The Framingham general cardiovascular risk score (FGCRS) in males at five years after SCT projected a doubling (median 10.4% vs. 5.4%) in the 10-year risk of cardiovascular events. Females received HRT after SCT, and none had increased FGCRS. Chronic GVHD and C-reactive protein were not associated with CVRF at any time. All CVRFs stabilized between five and ten years after SCT. Thus, SCT survivors have sustained elevations in CVRFs. Males have a significantly increased risk of cardiovascular events in their second and third decade after SCT.

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 donors 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 TCRVβ 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.

National Institutes of Health Hematopoietic Cell Transplantation Late Effects Initiative: The Immune Dysregulation and Pathobiology Working Group Report

Immune reconstitution after hematopoietic stem cell transplantation (HCT) beyond 1 year is not completely understood. Many transplant recipients who are free of graft-versus-host disease (GVHD) and not receiving any immunosuppression more than 1 year after transplantation seem to be able to mount appropriate immune responses to common pathogens and respond adequately to immunizations. However, 2 large registry studies over the last 2 decades seem to indicate that infection is a significant cause of late mortality in some patients, even in the absence of concomitant GVHD. Research on this topic is particularly challenging for several reasons. First, there are not enough long-term follow-up clinics able to measure even basic immune parameters late after HCT. Second, the correlation between laboratory measurements of immune function and infections is not well known. Third, accurate documentation of infectious episodes is notoriously difficult. Finally, it is unclear what measures can be implemented to improve the immune response in a clinically relevant way. A combination of long-term multicenter prospective studies that collect detailed infectious data and store samples as well as a national or multinational registry of clinically significant infections (eg, vaccine-preventable severe infections, opportunistic infections) could begin to address our knowledge gaps. Obtaining samples for laboratory evaluation of the immune system should be both calendar and eventdriven. Attention to detail and standardization of practices regarding prophylaxis, diagnosis, and definitions of infections would be of paramount importance to obtain clean reliable data. Laboratory studies should specifically address the neogenesis, maturation, and exhaustion of the adaptive immune system and, in particular, how these are influenced by persistent alloreactivity, inflammation, and viral infection. Ideally, some of these long-term prospective studies would collect information on long-term changes in the gut microbiome and their influence on immunity. Regarding enhancement of immune function, prospective measurement of the response to vaccines late after HCT in a variety of clinical settings should be undertaken to better understand the benefits as well as the limitations of immunizations. The role of intravenous immunoglobulin is still not well defined, and studies to address it should be encouraged.

Clinical and biological predictors of outcome following relapse of CML post-allo-SCT.

While there are now fewer allogeneic stem cell transplants (allo-SCT) performed for chronic myeloid leukemia (CML), leukemic relapse post-transplant remains a persistent problem. To better define clinical and biological parameters determining post-relapse outcome, we studied 59 patients with CML relapsing after HLA-identical sibling allo-SCT between 1993 and 2008. Eighteen (30.5%) were transplanted in advanced phase and 41(69.5%) in chronic phase. With a median follow up from relapse of 7.9 years, 5-year post-relapse survival (PRS) was 62%. Multivariate analysis found disease status at transplant, time to diagnosis of relapse from transplant, and pre- transplant TKI use as significant factors associated with PRS. Analysis of BCR-ABL transcript expression in the hematopoietic progenitor compartment was performed in 36 patients (22 relapsed, 8 non-relapsed, and 6 TKI alone controls). Patients with BCR-ABL expression in their early hematopoietic stem cell compartment (HSC: Lineage−CD34+CD38-CD90+) had worse survival irrespective of the disease status. We conclude disease status remains the strongest clinical prognostic factor for PRS in CML following allo-SCT. The persistence of BCR-ABL expression in the progenitor cell compartment in some patients after SCT emphasizes the need to target CML-leukemia stem cells.Although there are now fewer allo-SCTs performed for CML, leukemic relapse post transplant remains a persistent problem. To better define clinical and biological parameters determining postrelapse outcome, we studied 59 patients with CML relapsing after HLA-identical sibling allo-SCT between 1993 and 2008. Eighteen (30.5%) were transplanted in advanced phase and 41 (69.5%) in chronic phase. With a median follow-up from relapse of 7.9 years, 5-year post relapse survival (PRS) was 62%. Multivariate analysis found disease status at transplant, time to diagnosis of relapse from transplant and pretransplant tyrosine kinase inhibitor (TKI) use as significant factors associated with PRS. Analysis of BCR-ABL transcript expression in the hematopoietic progenitor compartment was performed in 36 patients (22 relapsed, 8 non-relapsed and 6 TKI alone controls). Patients with BCR-ABL expression in their early hematopoietic stem cell compartment (Lineage−CD34+CD38−CD90+) had worse survival irrespective of the disease status. We conclude that disease status remains the strongest clinical prognostic factor for PRS in CML following allo-SCT. The persistence of BCR-ABL expression in the progenitor cell compartment in some patients after SCT emphasizes the need to target CML-leukemia stem cells.

Clinical comorbidity predictive measures in ex vivo T-cell-depleted allogeneic hematopoietic stem cell transplantation

Clinical comorbidity predictive measures in ex vivo T-cell-depleted allogeneic hematopoietic stem cell transplantation