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1.
Optimizing Donor Chimerism Threshold for Next Generation Sequencing Monitoring of Measurable Residual Disease Post-Allogeneic Stem Cell Transplant for Myeloid Neoplasms
Puzo, C. J., Tormey, C. A., Rinder, H. M., Siddon, A. J.
Transplantation and cellular therapy. 2023
Abstract
BACKGROUND Next-Generation Sequencing (NGS) is used to monitor genetically-measurable residual disease (gMRD) following allogeneic stem cell transplant (aSCT). It is unknown whether an upper limit of chimerism exists such that gMRD NGS testing can be safely forgone. METHODS We reviewed 61 AML and 24 MDS patients between 2016-2020 with at least 1 NGS panel before and after aSCT. Donor chimerism was quantified. Logistic regression characterized which factors predicted gMRD. Receiver operator curves (ROC) determined the optimal chimerism threshold for which gMRD would not be detected. Data from an additional 22 patients with follow-up NGS testing in 2022, was also analyzed to validate our proposed threshold. RESULTS Donor chimerism (OR= 0.38, 95% CI[0.10,0.62], p=0.02), as expected, was a significant predictor of gMRD. Age, gender, conditioning regimen, presence of a related donor, and diagnosis were not associated with gMRD. A chimerism threshold of 92.5% optimized sensitivity (97.7) and specificity (95.4) such that values >92.5% strongly predicted absence of gMRD (AUC= .986). The validation cohort demonstrated similar strongly predictive capability (AUC= .974) with appropriate sensitivity (100%) and specificity (90.9%). CONCLUSION NGS monitoring of gMRD is redundant at chimerism values greater than a more conservative threshold of 92.5% after stem cell transplant.
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2.
Ultrasensitive Chimerism Enhances Measurable Residual Disease Testing Post-Allogeneic Hematopoietic Cell Transplantation
Kanaan, S. B., Urselli, F., Radich, J. P., Nelson, J. L.
Blood advances. 2023
Abstract
Increasing mixed chimerism (reemerging recipient cells) after allogeneic hematopoietic cell transplantation (allo-HCT) can indicate relapse, the leading factor determining mortality in blood malignancies. Most clinical chimerism tests have limited sensitivity and are primarily designed to monitor engraftment. We developed a panel of qPCR assays using TaqMan chemistry capable of quantifying chimerism on the order of 1-in-a-million. At such analytic sensitivity, we hypothesized it could inform on relapse risk. As a proof-of-concept, we applied our panel on a retrospective cohort of acute leukemia patients with known outcomes post-allo-HCT. Recipient cells in bone marrow aspirates (BMA) remained detectable in 97.8% of tested samples. Absolute recipient chimerism proportions and rates at which these proportions increased in BMA in the first 540 days post-allo-HCT were associated with relapse. Detectable MRD (measurable residual disease) by flow cytometry in BMA post-allo-HCT showed limited correlation with relapse. This correlation noticeably strengthened when combined with increased recipient chimerism in BMA, demonstrating the ability of our ultrasensitive chimerism assay to augment MRD data. Our technology reveals an underappreciated usefulness of clinical chimerism. Used side-by-side with MRD assays, it promises to improve identification of patients with the highest risk of disease reoccurrence for a chance for early intervention.
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3.
Bone marrow CD34+ molecular chimerism as an early predictor of relapse after allogeneic stem cell transplantation in patients with acute myeloid leukemia
Malagola, M., Polverelli, N., Beghin, A., Bolda, F., Comini, M., Farina, M., Morello, E., Radici, V., Accorsi Buttini, E., Bernardi, S., et al
Frontiers in oncology. 2023;13:1133418
Abstract
BACKGROUND Minimal residual disease (MRD) monitoring is an important tool to optimally address post-transplant management of acute myeloid leukemia (AML) patients. METHODS We retrospectively analyzed the impact of bone marrow CD34+ molecular chimerism and WT1 on the outcome of a consecutive series of 168 AML patients submitted to allogeneic stem cell transplantation. RESULTS The cumulative incidence of relapse (CIR) was significantly lower in patients with donor chimerism on CD34+ cells ≥ 97.5% and WT1 < 213 copies/ABL x 10^4 both at 1(st) month (p=0.008 and p<0.001) and at 3(rd) month (p<0.001 for both). By combining chimerism and WT1 at 3(rd) month, 13 patients with chimerism < 97.5% or WT1 > 213 showed intermediate prognosis. 12 of these patients fell in this category because of molecular chimerism < 97.5% at a time-point in which WT1 was < 213. CONCLUSIONS Our results confirm that lineage-specific molecular chimerism and WT1 after allo-SCT (1(st) and 3(rd) month) are useful MRD markers. When considered together at 3(rd) month, CD34+ molecular chimerism could represent an earlier predictor of relapse compared to WT1. Further studies are necessary to confirm this preliminary observation.
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4.
Is Mixed Chimerism Post-allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Acute Lymphoid Leukemia a Prognostic Factor for Relapse?
Khan, S., AlSaif, Z., Siddiqui, K., AlSaedi, H., Al-Ahmari, A., Al-Jefri, A., Ghemlas, I., AlAnazi, A., Ayas, M.
Hematology/oncology and stem cell therapy. 2023;17(1):72-78
Abstract
Hematopoietic stem cell transplantation (HSCT) has been considered curative for children with high-risk acute leukemia (ALL), offering better survival. Short tandem repeat has been used as a marker of chimerism status after HSCT. The appearance of recipient cells >1% post-allogeneic stem cell transplant is defined as mixed chimerism (MC). Chimeric studies post-HSCT are dynamic. This study aimed to investigate the significance of recipient cells in post-HSCT pediatric ALL patients as a predictor of relapse of their primary disease. The rate of MC was 51.4% (19 out of 37 recipients). It was 48.6% (n = 18) during Day+100 and 12.9% (4 out of 31 recipients) during post-Day+100 follow-up until two years. No significant association was noted between MC and all grade overall acute graft-versus-host disease. A mortality rate of 35.1% (n = 13) and a median follow-up of 56.9 months (95% CI: 39.7-74.2) were observed for all but four (16.7%) of the survivors in remission. Regarding causes of death, transplant-related mortality was recorded in only 2 of 13 expired patients (15.4%); both succumbed to sepsis. No significant association was found between MC and primary causes of death. The cumulative probability of five-year overall survival and event-free survival was not found to be statistically significantly different for MC (≤1.0% vs. > 1.0%). In conclusion, our data did not show MC testing alone as an effective prognostic marker for detecting relapse; molecular and flow cytometric analyses should be considered in children with ALL post-HSCT for monitoring relapse.
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5.
Peripheral blood CD34 donor chimerism has greater clinical utility than CD3 for detecting relapse after allogeneic stem cell transplantation for AML or MDS
Das, T. P., North, D., Fleming, S. A., Tan, J. L. C., Ivey, A., Cummings, N. J., Spencer, A., Patil, S. S., Widjaja, J. M. L., Swain, M. I., et al
Transplantation and cellular therapy. 2023
Abstract
BACKGROUND Monitoring donor chimerism (DC) may detect early relapse following allogeneic hematopoietic stem cell transplant for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). Most centers use unfractionated peripheral blood or T-cells to monitor DC although CD34(+) DC may be more predictive. Limited adoption of CD34(+) DC may be due to the lack of detailed, comparative studies. OBJECTIVE To address this knowledge gap, we compared peripheral blood CD34(+) and CD3(+) DC in 134 patients transplanted for AML or MDS. STUDY DESIGN In July 2011, the Alfred Hospital Bone Marrow Transplantation Service adopted routine monitoring of DC in the lineage-specific CD34(+) and CD3(+) cell subsets from peripheral blood at 1, 2, 3, 4, 6, 9 and 12-months post-transplant for AML or MDS. Immunologic interventions including rapid immune suppression withdrawal, azacytidine and donor lymphocyte infusions were pre-specified for CD34(+) DC ≤80%. RESULTS Overall, CD34(+) DC ≤80% detected 32 of 40 relapses (positive predictive value 68% and negative predictive value 91%) compared with 13 of 40 relapses for CD3(+) DC ≤80% (positive predictive value 52% and negative predictive value 75%). Receiver operator analysis showed superiority of CD34(+) DC, with the most value at Day 120. CD3(+) DC provided additional value in only 3 cases, preceding CD34(+) DC ≤80% by 1 month. We further show that the CD34(+) DC sample can be used to detect NPM1(mut), with the combination of CD34(+) DC ≤80% and NPM1(mut) identifying the highest risk of relapse. For patients in morphologic remission at the time of CD34(+) DC ≤80% (n=24), 13 patients (54%) responded to immunologic interventions (rapid withdrawal of immunosuppression, azacitidine or donor lymphocyte infusions) with recovery of CD34(+) DC >80% and 11 of these patients remained in complete remission for a median of 34 months (range 28-97 months). In contrast, the other 9 patients did not respond to the clinical intervention and relapsed within a median of 59 days after detecting CD34(+) DC ≤80%. The CD34(+) DC of responders (median 72%) was significantly higher than non-responders (56%) (p=0.015, Mann-Whitney U test). Overall, monitoring CD34(+) DC was considered clinically useful (early diagnosis of relapse enabling pre-emptive therapy or predicting low risk of relapse) in 107 of 125 (86%) evaluable patients. CONCLUSIONS We show that peripheral blood CD34(+) DC is feasible and superior to CD3(+) DC for predicting relapse. It also provides a source of DNA for MRD testing, which may further stratify risk of relapse. If validated by an independent cohort, our results suggest that CD34(+) should be used in preference to CD3(+) DC for detecting early relapse and guiding immunologic interventions following transplant for AML or MDS.
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6.
Posttransplant MRD and T-cell chimerism status predict outcomes in patients allografted with AML/MDS
Loke, J., McCarthy, N., Jackson, A. E., Siddique, S., Hodgkinson, A., Mason, J., Crawley, C. R., Gilleece, M., Peniket, A. J., Protheroe, R., et al
Blood advances. 2023
Abstract
Allogeneic stem-cell transplantation allows the delivery of curative graft-versus-leukemia (GVL) in patients with acute myeloid leukemia/myelodysplasia (AML/MDS). Surveillance of T-cell chimerism, measurable residual disease (MRD) and blast HLA-DR expression may inform whether GVL effectiveness is reduced. We report the prognostic impact of these biomarkers in patients allografted for AML/MDS. 187 patients from FIGARO, a randomized trial of reduced-intensity conditioning regimens in AML/MDS, were alive and relapse-free, at the first MRD timepoint and provided bone marrow for flow cytometric MRD monitoring and blood samples for T-cell chimerism analysis, requested to month+12. 29 (15.5%) patients had at least one MRD-positive result post-transplant. MRD-positivity was associated with reduced overall survival (OS) (HR:2.18, p=0.0028) as a time-varying Cox variable and remained significant irrespective of pre-transplant MRD status in multivariate analyses (p<0.001). 94 patients had sequential MRD with T-cell chimerism results at months+3/+6. Patients with full donor T-cell chimerism (FDTC) had an improved OS as compared with patients with mixed-donor T-cell chimerism (MDTC) (adjusted-HR=0.4, p=0.0019). In patients with MDTC (month+3 or +6), MRD-positivity was associated with decreased 2yr-OS (34.3% [95% CI:11.6-58.7] versus MRD-negative 71.4% [95% CI:52.2-84.0], p=0.001). In contrast, in the group with FDTC, MRD was infrequent and did not impact outcome. Amongst patients with post-transplant MRD-positivity, decreased HLA-DR expression on blasts significantly reduced OS, supporting this as a mechanism for GVL escape. Post-transplant MRD is an important predictor of outcome in patients allografted for AML/MDS and is most informative when combined with T-cell chimerism results, underlining the importance of a GVL effect in AML/MDS.
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7.
Utility of assessing CD3(+) cell chimerism within the first months after allogeneic hematopoietic stem-cell transplantation for acute myeloid leukemia
Bendjelloul, M., Usureau, C., Etancelin, P., Saidak, Z., Lebon, D., Garçon, L., Marolleau, J. P., Desoutter, J., Guillaume, N.
Hla. 2022;100(1):18-23
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Abstract
After allogeneic hematopoietic stem-cell transplantation (alloHSCT), the chimerism assay is used to monitor cell engraftment and quantify the respective proportions of donor/recipient cells in blood or bone-marrow samples. Here, we aimed to better assess the utility of determining CD3(+) cell chimerism within the first 6 months post alloHSCT. One hundred and thirty five patients diagnosed with acute myeloid leukemia were enrolled in this study. We observed significantly lower overall survival and relapse free survival for patients without full donor chimerism (<95%, <98%, <99%) in whole blood at Day 30, as well as at Day 90 after alloHSCT, than for patients with full donor chimerism. This outcome was not observed when assessing selected CD3(+) cells. However, at Day 90, patients with discordant whole blood versus selected CD3(+) cell chimerism showed both significantly lower overall survival and relapse free survival, giving an interest to assess selected cells chimerism.
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8.
Impact on outcomes of mixed chimerism of bone marrow CD34+ sorted cells after matched or haploidentical allogeneic stem cell transplantation for myeloid malignancies
Le Bris, Y., Costes, D., Bourgade, R., Guillaume, T., Peterlin, P., Garnier, A., Le Bourgeois, A., Chevallier, P., Béné, M. C.
Bone marrow transplantation. 2022
Abstract
Allogeneic hematopoietic stem cell transplantation (Allo-HSCT), proposed to patients with high-risk myeloid malignancies, may ultimately fail because of disease relapse. Bone marrow (BM) CD34(+) cells in Allo-HSCT recipients can be either re-emerging recipient malignant cells or donor cells attesting of hematopoietic reconstitution. In this context, investigating donor/recipient chimerism in the population of BM CD34(+) sorted cells (BM-CD34(+)SC) was performed in 261 Allo-HSCT recipients (matched n = 145, haploidentical n = 65, matched unrelated n = 51) with myeloid malignancies. BM-CD34(+)SC chimerism was compared to that of whole peripheral blood (PB) cells as well as other Allo-HSCT-related parameters, and impact on relapse and survival was assessed. Thresholds of 98% donor cells for PB and 90% for BM-CD34(+)SC were found to allow relapse prediction. This was completed by the application of machine learning tools to explore the predictive value of these parameters in multidimensional models with repeated iterations. BM-CD34(+)SC mixed chimerism stood out with all these methods as the most robust predictor of relapse with a significant impact on disease-free and overall survivals even after haploidentical Allo-HSCT and/or PTCY administration. This marker therefore appears to be of great interest for the decision of preemptive treatment to avoid post-transplant relapse.
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9.
Early relapse prediction after allogeneic hematopoietic stem cell transplantation for acute lymphoblastic leukemia (ALL) using lineage-specific chimerism analysis
Lindahl, H., Valentini, D., Vonlanthen, S., Sundin, M., Björklund, A. T., Mielke, S., Hauzenberger, D.
EJHaem. 2022;3(4):1277-1286
Abstract
Relapse is a major cause of treatment failure after hematopoietic stem cell transplantation (HSCT) for acute leukemia. Here, we report a monocentric retrospective study of all HSCTs for B cell acute lymphoblastic leukemia (ALL) performed during the years 2005-2021 (n = 138, including 51 children), aiming to identify the optimal use of lineage-specific recipient-donor chimerism analysis for prediction of relapse. In adults, relapse was associated with increased recipient chimerism in CD3(+) bone marrow cells sampled at least 30 days before a relapse. Relapse could be predicted with a sensitivity of 73% and a specificity of 83%. Results were similar for children but with a higher recipient chimerism cutoff. Additionally, adults that had at least one chimerism value <0.12% in CD3(+) peripheral blood cells within the first 60 days after HSCT had 89% probability of being relapse-free after 2-years compared to 64%. Results were similar for children but again necessitating a higher chimerism cutoff. These results suggest that high-sensitive lineage-specific chimerism analysis can be used for (1) early ALL relapse prediction by longitudinal chimerism monitoring in CD3(+) bone marrow cells and (2) relapse risk stratification by analyzing CD3(+) blood cells early post-HSCT.
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10.
Lineage-specific early complete donor chimerism and risk of relapse after allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia
Lindahl, H., Vonlanthen, S., Valentini, D., Björklund, A. T., Sundin, M., Mielke, S., Hauzenberger, D.
Bone marrow transplantation. 2022
Abstract
Recipient-donor chimerism is routinely analyzed after allogeneic hematopoietic stem cell transplantation (HSCT) to monitor engraftment and graft rejection. For malignancies, chimerism can also be used to screen for disease relapse post-HSCT but methodology and interpretation of results are not standardized and likely depend on underlying diagnosis. We have implemented highly sensitive and accurate methodologies for chimerism analysis for the purpose of improving relapse prediction. Here, we report an exploratory retrospective analysis of clinical routine chimerism results from all 154 HSCTs for acute myeloid leukemia (AML) performed at our center during the years 2015-2020 with the aim of suggesting a clinically useful threshold at which risk of relapse is high. Relapse was not reliably predicted based on single elevated chimerism values obtained before time of overt relapse. However, early complete donor chimerism, here defined as recipient DNA < 0.2% in CD33(+) cells in any blood or bone marrow sample taken during the first 60 days after HSCT, correlated inversely with relapse during the observation time (log-rank test P = 0.033). We propose that achievement of complete chimerism determined early after HSCT using sensitive methods can be used for risk-stratification of AML patients.