Assessment of chimerism by next generation sequencing: A comparison to STR/qPCR methods.

Chimerism analysis is used to evaluate patients after allogeneic hematopoietic stem cell transplant (allo-HSCT) for engraftment and minimal measurable residual disease (MRD) monitoring. A combination of short-tandem repeat (STR) and quantitative polymerase chain reaction (qPCR) was required to achieve both sensitivity and accuracy in the patients with various chimerism statuses. In this study, an insertion/deletion-based multiplex chimerism assay by next generation sequencing (NGS) was evaluated using 5 simulated unrelated donor-recipient combinations from 10 volunteers. Median number of informative markers detected was 8 (range = 5 - 11). The limit of quantitation (LoQ) was determined to be 0.1 % recipient. Assay sample number/batch was 10-20 and total assay time was 19-31 h (manual labor = 2.1 h). Additionally, 50 peripheral blood samples from 5 allo-HSCT recipients (related: N = 4; unrelated: N = 1) were tested by NGS and STR/qPCR. Median number of informative markers detected was 7 (range = 4 - 12). Results from both assays demonstrated a strong correlation (Y = 0.9875X + 0.333; R2 = 0.9852), no significant assay bias (difference mean - 0.08), and 100 % concordant detection of percent recipient increase ≥ 0.1 % (indicator of increased relapse risk). NGS-based chimerism assay can support all allo-HSCT for engraftment and MRD monitoring and simplify clinical laboratory workflow compared to STR/qPCR.

Significance of Degree of HLA Disparity Using T-cell Replete Peripheral Blood Stem Cells From Haploidentical Donors With Posttransplantation Cyclophosphamide in AML in First Complete Hematologic Remission: A Study of the Acute Leukemia Working Party of the EBMT.

Availability of haploidentical donors has broadened utilization of allogeneic hematopoietic cell transplantation (allo-HCT). Peripheral blood stem cells (PBSC) are being used with increased frequency in haploidentical allo-HCT. We evaluated extent of HLA disparity (2-3/8 versus 4/8 HLA antigen mismatches) on post-allograft outcomes when using T-cell replete PBSC from haploidentical donors for acute myeloid leukemia in first complete remission. Primary objectives entailed assessing cumulative incidence of grade 2-4 acute graft-versus-host disease (GVHD) and chronic GVHD (any grade). A total of 645 patients received a haploidentical allo-HCT from a donor with either 2-3 of 8 HLA antigen mismatches (n = 180) or with 4 of 8 HLA antigen mismatches (n = 465). Presence of 2-3 of 8 versus 4 of 8 HLA mismatches did not affect the incidence of acute GVHD (grade 2-4) and chronic GVHD (any grade). Overall survival (OS), leukemia-free survival (LFS) relapse incidence (RI), nonrelapse mortality and the composite endpoint of GVHD-free relapse-free survival were also similar among the groups. Pertaining to HLA-B leader matching effect, our analysis did not discern any difference in aforementioned post-allograft outcomes for this variable. However, in univariate analysis, absence of an antigen mismatch in HLA-DPB1 showed a trend for better OS. Notwithstanding inherent limitations associated with registry data, our results did not show an advantage of selecting a haploidentical donor with 2-3 of 8 HLA antigen mismatches over one with 4 of 8 HLA antigen mismatches when using PBSC as the cell source. Adverse cytogenetics remains a major adverse determinant of inferior OS and LFS and a higher RI. Using reduced-intensity conditioning yielded worse OS and LFS.

ASBMT Practice Guidelines Committee Survey on Long-Term Follow-Up Clinics for Hematopoietic Cell Transplant Survivors.

Significant advances in hematopoietic cell transplantation (HCT) have increased the long-term survivorship of its recipients, but because of unique complications arising from radiation and chemotherapy, recipients require lifelong follow-up. To evaluate current survivorship or long-term follow-up (LTFU) clinics specifically for HCT survivors and to evaluate the potential barriers in their establishment, the American Society for Blood and Marrow Transplantation (ASBMT) Practice Guidelines Committee electronically surveyed 200 HCT programs to gather quantitative and qualitative data about models of care. Among 77 programs (38.5%) that responded, 45% indicated presence of an LTFU clinic; however, LTFU care models varied with respect to services provided, specialist availability, type of patients served, and staffing. Among 55% of programs without an LTFU clinic, 100% agreed that allogeneic HCT survivors have unique needs separate from graft-versus-host disease and that complications could arise during the transition of care either from pediatric to adult settings or away from the HCT center. Lack of expertise, logistics, financial issues, and the observation that 84% of individual practitioners prefer to provide survivorship care were the identified obstacles to establishing new LTFU clinics. The ASBMT hopes that policymakers, HCT providers, and institutions will benefit from the results of this survey and recommends that delivering guidelines-driven screening and expert management of late effects is the goal of first-rate HCT survivorship care.

Outcomes of Medicare-age eligible NHL patients receiving RIC allogeneic transplantation: a CIBMTR analysis.

The application of allogeneic hematopoietic cell transplantation (allo-HCT) in non-Hodgkin lymphoma (NHL) patients ≥65 years in the United States is limited by lack of Medicare coverage for this indication. Using the Center for International Blood and Marrow Transplant Research (CIBMTR) database, we report allo-HCT outcomes of NHL patients aged ≥65 years (older cohort; n = 446) compared with a cohort of younger NHL patients aged 55-64 years (n = 1183). We identified 1629 NHL patients undergoing a first reduced-intensity conditioning (RIC) or nonmyeloablative conditioning allo-HCT from 2008 to 2015 in the United States. Cord blood or haploidentical transplants were excluded. The median age was 68 years (range 65-77) for the older cohort vs 60 years (range 55-64) in the younger cohort. The 4-year adjusted probabilities of nonrelapse mortality (NRM), relapse/progression (R/P), progression-free survival (PFS), and overall survival (OS) of the younger and older groups were 24% vs 30% (P = .03), 41% vs 42% (P = .82), 37% vs 31% (P = .03), and 51% vs 46% (P = .07), respectively. Using multivariate analysis, compared with the younger group, the older cohort was associated with increased NRM, but there was no difference between the 2 cohorts in terms of R/P, PFS, or OS. The most common cause of death was disease relapse in both groups. In NHL patients eligible for allo-HCT, there was no difference in OS between the 2 cohorts. Age alone should not determine allo-HCT eligibility in NHL, and Medicare should expand allo-HCT coverage to older adults.

Assessment of Impact of HLA Type on Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation for Chronic Lymphocytic Leukemia.

Chronic lymphocytic leukemia (CLL) is a common hematologic malignancy with many highly effective therapies. Chemorefractory disease, often characterized by deletion of chromosome 17p, has historically been associated with very poor outcomes, leading to the application of allogeneic hematopoietic stem cell transplantation (allo-HCT) for medically fit patients. Although the use of allo-HCT has declined since the introduction of novel targeted therapy for the treatment of CLL, there remains significant interest in understanding factors that may influence the efficacy of allo-HCT, the only known curative treatment for CLL. The potential benefit of transplantation is most likely due to the presence of alloreactive donor T cells that mediate the graft-versus-leukemia (GVL) effect. The recognition of potentially tumor-specific antigens in the context of class I and II major histocompatibility complex on malignant B lymphocytes by donor T cells may be influenced by subtle differences in the highly polymorphic HLA locus. Given previous reports of specific HLA alleles impacting the incidence of CLL and the clinical outcomes of allo-HCT for CLL, we sought to study the overall survival and progression-free survival of a large cohort of patients with CLL who underwent allo-HCT from fully HLA-matched related and unrelated donors at Center for International Blood and Marrow Transplant Research transplantation centers. We found no statistically significant association of allo-HCT outcomes in CLL based on previously reported HLA combinations. Additional study is needed to further define the immunologic features that portend a more favorable GVL effect after allo-HCT for CLL.

Decision analysis of peripheral blood versus bone marrow hematopoietic stem cells for allogeneic hematopoietic cell transplantation.

Peripheral blood stem cells (PBSCs) and bone marrow (BM) hematopoietic stem cells represent therapeutic alternatives in allogeneic hematopoietic cell transplantation. Randomized controlled trials and an individual patient data meta-analysis (IPDMA) have demonstrated a decreased risk of disease relapse and an increased risk of acute and chronic graft-versus-host disease (aGVHD, cGVHD) in patients receiving PBSCs compared with those receiving BM stem cells. Decision modeling provides quantitative integration of the risks and benefits associated with these alternative treatments, incorporates survival discounts for lower quality of life in patients with aGVHD or cGVHD and post-transplantation relapse, and allows sensitivity analyses for all model assumptions. We have constructed an externally validated Markov model to represent and analyze the decision to use PBSC or BM, estimating post-transplantation state transition probabilities (eg, GVHD and relapse) and quality-of-life discounts from the IPDMA and relevant literature; importantly, this IPDMA synthesized data from primarily adult patients treated with myeloablative (MA) conditioning regimens with T cell-replete matched sibling donors. In this setting, the model demonstrates the superiority of PBSC over BM in both overall and quality-adjusted life expectancy, with a 7-month advantage for PBSC. Sensitivity analyses support this conclusion through a range of values for each variable supported by the IPDMA and quality-of-life discounts, as supported by the literature. However, BM is the optimal strategy in conditions in which the 1-year relapse probability is < 5%. PBSC is the optimal stem cell source in terms of both overall and quality-adjusted life expectancy, except in conditions with a very low relapse probability, in which BM provides optimal outcomes.

Microbial contamination of hematopoietic progenitor cell grafts-incidence, clinical outcome, and cost-effectiveness: an analysis of 735 grafts.

BACKGROUND: Screening of progenitor cell grafts (marrow, peripheral blood, and cord blood) for microbial contamination is required by the standards of AABB. Clinical sequelae from infusion of these contaminated grafts, however, is uncommon. STUDY DESIGN AND METHODS: A retrospective analysis of 735 consecutive marrow and peripheral blood progenitor cell harvests between 1998 and 2003 was performed. Analysis included incidence, clinical outcome, and cost outcomes of positive blood cultures and antibiotic therapy. RESULTS: Thirty-three of 735 (4.5%) harvests were contaminated. The incidence of microbial contamination varied with the source of the graft (4 of 26 [15%] were cord blood, 8 of 177 [4.5%] were marrow, and 21 of 532 [3.9%] were peripheral blood). Coagulase-negative Staphylococcus (n=22) and Propionibacterium acnes (n=8) were most frequently isolated. Potentially pathogenic organisms were isolated in 6 of 735 (0.81%) grafts (methicillin-sensitive Staphylococcus aureus, 4; methicillin-resistant S. aureus, 1; and Enterobacter cloacae, 1). The estimated total cost of surveillance was approximately $81,585. The cost of vancomycin therapy in 4 patients who received prophylactic antibiotic therapy was approximately $10,000. No adverse sequelae followed infusion of contaminated grafts. CONCLUSION: Clinical sequelae following infusion of microbially contaminated progenitor cells is extremely rare. Prophylactic empiric antibiotics may be unnecessary. Routine microbial surveillance of progenitor cell grafts is a low-yield procedure.