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Article

Assessment of Minimal Residual Disease by Next Generation Sequencing in Peripheral Blood as a Complementary Tool for Personalized Transplant Monitoring in Myeloid Neoplasms

by
Paula Aguirre-Ruiz
1,
Beñat Ariceta
1,2,
María Cruz Viguria
2,3,
María Teresa Zudaire
2,3,
Zuriñe Blasco-Iturri
1,
Patricia Arnedo
3,
Almudena Aguilera-Diaz
2,4,
Axier Jauregui
3,
Amagoia Mañú
1,2,
Felipe Prosper
2,4,5,
María Carmen Mateos
2,3,
Marta Fernández-Mercado
1,2,4,
María José Larráyoz
1,2,
Margarita Redondo
2,3,
María José Calasanz
1,2,
Iria Vázquez
1,2,* and
Eva Bandrés
2,3,*
1
Hematological Diseases Laboratory, CIMA LAB Diagnostics, University of Navarra, 31008 Pamplona, Navarra, Spain
2
Navarra Institute for Health Research (IdiSNA), 31008 Pamplona, Navarra, Spain
3
Hematology Department, Complejo Hospitalario de Navarra, 31008 Pamplona, Navarra, Spain
4
Advanced Genomics Laboratory, Hemato-Oncology, Center for Applied Medical Research (CIMA), 31008 Pamplona, Navarra, Spain
5
Hematology Department, Clinica Universidad de Navarra (CUN), 31008 Pamplona, Navarra, Spain
*
Authors to whom correspondence should be addressed.
J. Clin. Med. 2020, 9(12), 3818; https://doi.org/10.3390/jcm9123818
Submission received: 2 November 2020 / Revised: 20 November 2020 / Accepted: 23 November 2020 / Published: 25 November 2020
(This article belongs to the Section Clinical Laboratory Medicine)

Abstract

:
Patients with myeloid neoplasms who relapsed after allogenic hematopoietic stem cell transplant (HSCT) have poor prognosis. Monitoring of chimerism and specific molecular markers as a surrogate measure of relapse is not always helpful; therefore, improved systems to detect early relapse are needed. We hypothesized that the use of next generation sequencing (NGS) could be a suitable approach for personalized follow-up post-HSCT. To validate our hypothesis, we analyzed by NGS, a retrospective set of peripheral blood (PB) DNA samples previously evaluated by high-sensitive quantitative PCR analysis using insertion/deletion polymorphisms (indel-qPCR) chimerism engraftment. Post-HCST allelic burdens assessed by NGS and chimerism status showed a similar time-course pattern. At time of clinical relapse in 8/12 patients, we detected positive NGS-based minimal residual disease (NGS-MRD). Importantly, in 6/8 patients, we were able to detect NGS-MRD at time points collected prior to clinical relapse. We also confirmed the disappearance of post-HCST allelic burden in non-relapsed patients, indicating true clinical specificity. This study highlights the clinical utility of NGS-based post-HCST monitoring in myeloid neoplasia as a complementary specific analysis to high-sensitive engraftment testing. Overall, NGS-MRD testing in PB is widely applicable for the evaluation of patients following HSCT and highly valuable to personalized early treatment intervention when mixed chimerism is detected.

1. Introduction

Allogenic hematopoietic stem cell transplant (HSCT) is a potentially curative treatment in patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), reducing risk of relapse and improving overall survival [1,2,3]; however, clinical outcomes still vary among patients [4,5,6,7]. Due to the high mortality rate and treatment failures, improved methods of disease status monitoring are clearly needed for patients with myeloid neoplasia following HSCT. Improved surveillance systems may facilitate earlier therapeutic interventions and potentially prevent disease recurrence by tapering immunosuppression, treatment with lymphocyte donor infusion or initiation of anti-neoplastic treatment [8,9]. Standard methodologies to detect clinical relapse in myeloid neoplasms currently include: morphologic assessment of the bone marrow (BM), minimal residual disease (MRD) detection by flow cytometry, cytogenetic or molecular genetic marker detection, and hematopoietic chimerism testing. BM histological analysis has a reduced sensitivity for clinical relapse detection [10]. MRD assessment by flow cytometry for AML and MDS is often complicated due to variable sensitivity of patient-specific marker expression profiles, and can also be subject to inter-assay and inter-operator variability [11]. For chimerism analysis, short tandem repeat (STR) polymerase Chain Reaction (PCR) assays are generally applicable to all HSCT patients, but are limited by a sensitivity threshold of 1–5% [12,13,14]. Newer techniques to analyze chimerism with higher sensitivity (0.01–0.1%) have relatively recently emerged, such as quantitative PCR analysis using insertion/deletion polymorphisms (indel-qPCR) and droplet-digital PCR (ddPCR) [15,16,17]. However, these assays do not specifically detect the presence of disease, but rather they offer a percentage of recipient’s DNA as a surrogate measure for recurrence. This lack of specificity is particularly problematic in chimerism assays, showing high sensitivity, as non-malignant recipient cell lineages may be present in various sample types without representing disease relapse [18]. To maximize sensitivity and specificity, assays such as reverse transcriptase polymerase chain reaction (RT-PCR) may be applied to follow-up specific genetic alterations [19]; however, this is a major limitation in a disease characterized by a striking broad array of different potential oncogenic events across a notable number of genes.
Recently, next generation sequencing (NGS) has been applied to identify clinically relevant variants in AML [20], and persistent allelic burden after chemotherapy has been associated with higher incidence of relapse [21]. Moreover, the presence of genetic variants before HSCT has been associated with higher risk of relapse and shorter overall survival after HSCT [22,23]. Likewise, several studies have demonstrated that the presence of a higher allelic burden at the time of morphologic complete remission is associated with an increased risk of relapse and mortality in AML patients [24,25] and have suggested that the presence of certain genetic variants at morphologic complete remission could be responsible for high risk [26]. Therefore, there has been a great interest to develop high-sensitivity assays to detect any trace of myeloid malignant cells before and after HSCT.
We hypothesized that peripheral blood (PB) serial samples collected for chimerism status monitorization could be useful for NGS analysis, in order to track genetic variants with no additional invasive biopsy procedures. The aim of the present study was to assess the allelic burden in PB using a custom NGS panel alongside measuring the engraftment status using our laboratory’s standard-of-care technique for chimerism engraftment monitoring of post-HSCT patients. With these combined datasets, we intended to establish the value of NGS data during chimerism monitorization and assess their combined capacity for personalized early discrimination of molecular relapse, in order to facilitate earlier therapeutic interventions when mixed chimerism (MC) is detected.

2. Experimental Section

2.1. Patient Cohorts and Acquisition of Samples

A retrospective study, approved by the DIANA project review board (0011-1411-2017-000028), was designed to assess the utility of NGS-MRD detection after HSCT using PB samples collected for routine clinical engraftment analysis. We selected 20 patients (12 AML, 8 MDS/chronic myelomonocytic leukemia—CMML) with a variety of chimerism profiles and treatment protocols. Briefly, 12 patients had reduced-intensity conditioning regimen (busulfan plus fludarabine) and 8 patients had a myeloablative conditioning regimen (busulfan plus fludarabine or cyclophosphamide); Graft versus Host Disease (GVHD) prophylaxis was performed with a calcineurin inhibitor (cyclosporine or FK506) with methotrexate; T-depletion was performed for unrelated-donor transplantation; and post-HSCT maintenance therapies were not administered until clinical relapse detection (Table 1). Frequency of chimerism monitoring based on high-risk factors presence and clinical grounds was performed by indel-qPCR analysis on 296 PB DNA samples (mean 15 samples per patient; range 7–29). We selected 75 PB samples for NGS analysis (18 diagnosis, 1 post-induction, and 56 post-HSCT: 45 samples had Mixed chimerism (MC) and 11 had complete chimerism (CC) based on chimerism fluctuations and clinical data (Supplementary Materials Figure S1). Clinical relapse was defined when leukemia blasts were identified by morphological analysis or flow cytometry, or cytogenetic or non-NGS genetic markers were detected. According to these criteria, two groups of patients were studied: patients who relapsed after HSCT (n = 12) and patients without relapse at the end of study (n = 8). In both groups, we included patients achieving CC at some point during the follow up and patients with MC after HSCT (Supplementary Materials Figure S1). Two donor samples and 8 paired-bone marrow (BM) samples were also included (4 diagnosis, 4 follow-up).

2.2. Indel-qPCR Chimerism Analysis

DNA was isolated from 400 µL of total PB buffy coat using QIAamp DNA Blood Mini Kit (Qiagen, Hilden, Germany) and quantified by Nanodrop Spectrophotometer (Nanodrop Technologies, Wilmington, NC, USA). Baseline donor and recipient DNA were genotyped with the KMR Genotyping Kit (GenDx, Utrecht, The Netherlands) and informative markers were selected (positive in recipient and negative in donor). Chimerism presence was tested by KMR Track Kit (GeneDx), with post-HSCT DNA (150 ng) and pre-HSCT recipient DNA (10 ng), and the chimerism percentages, represented as host-DNA percentages, were determined using the ddCt method according to the manufacturer’s instructions [27]. We defined complete chimerism (CC) as host-DNA percentage inferior to 0.01% and mixed chimerism (MC) as host-DNA percentage above this threshold.

2.3. Next Generation Sequencing (NGS)

DNA samples were quantified using Qubit dsDNA BR Assay Kit on a Qubit 3.0 Fluorometer (Life Technologies, Carlsbad, CA, USA), and quality was assessed by DNA genomic kit on a Tape Station 4100 (Agilent Technologies, Santa Clara, CA, USA). Samples at diagnosis and post-HSCT were analyzed with a custom pan-myeloid panel targeting 48 myeloid genes described by Aguilera-Diaz et al. [28]. Libraries were carried out following manufacturer’s instructions, quantified using the Qubit dsDNA HS Assay Kit on a Qubit 3.0 Fluorometer (Life Technologies), and quality was assessed using the D1000 Kit on the 4100 Tape Station (Agilent Technologies); 8 pooled libraries were normalized at 4 nM and pair-end sequenced on a MiSeq Sequencer (Illumina, San Diego, CA, USA) with 251 × 2 cycles using the Reagent Kit V3 600 cycles cartridge (Illumina, San Diego, CA, USA).

2.4. Variant Data Analysis

Fastq files were uploaded onto SOPHiA DDM software (SOPHiA GENETICS, Saint Sulpice, Switzerland) for alignment, variant calling, and annotation, filtering out intronic and intergenic variants. Aligned reads were manually curated with the Integrative Genomics Viewer (IGV) software (Broad Institute, Cambridge, MA, USA).
In addition, two in-house hotspot variant calling analyses were performed using VarScan version 2.4.2 [29] and GATK version 4.0.8.1 Mutect2 [30] to detect variants with variant allele frequency (VAF) below 1% threshold. The filtering values for VarScan analysis were: strand bias; minimum coverage: 2; minimum supporting reads at a position to call variants: 2; minimum base quality at a position to count a read: 1; and minimum VAF: 10-5. For Mutect2 analysis, the parameters were: minimum base quality required to consider a base for calling was reduced to 1, the minimum phred-scaled confidence threshold at which variants should be called to 1 and the maximum number of reads to retain per alignment start position was disabled. Mutect2 was run in tumor-only mode and with hotspots as interval list to reduce computing time. Variants from both methods were manually curated to confirm the hotspots selected for each patient.
Clinical classification of the resulting variants was individually reviewed according to the Spanish Group of Myelodysplastic Syndromes guidelines [31]. Post-HSCT monitoring was performed considering all NGS-trackable variants, meaning variants that: (i) were classified as pathogenic, likely pathogenic, or variants of uncertain significance (VUS); (ii) had a minimum coverage of 500 reads; (iii) had a minimum of 12 reads of the alternative allele; and (iv) had a VAF ≥ 0.1% with at least one of their time points with VAF > 5%. Regarding MRD by NGS in post-HSCT, a sample was considered NGS-MRD positive when a variant with clinical relevance, including pathogenic and/or likely pathogenic variants, was detected.

3. Results

3.1. Assessment of the NGS Sensitivity on PB Samples

First, we assessed the sensitivity of NGS on PB samples in comparison to BM paired samples by Pearson correlation test. We compared 4 PB and BM samples at diagnosis, and similar VAF were detected showing similar sensitivity (R2 = 0.9891; p-value < 0.0001). Besides, comparison of 4 PB and BM samples at follow-up times showed high correlation (R2 = 0.9978; p-value < 0.0001) (Supplementary Materials Figure S2).
These results showed similar sensitivity of NGS on PB and BM samples both for the diagnosis and follow-up, confirming that PB samples are also suitable for molecular testing when BM is not available.

3.2. Identification of NGS Variants in PB of Myeloid Neoplasms

We analyzed samples collected at the time of diagnosis (n = 18) or at post-induction treatment time (n = 1); no sample before HSCT was available for unique patient number (UPN)20. The remaining 19 patients showed a total of 57 variants. Considering variants of UPN20 and de novo acquired variants during the follow-up, the number of total detected variants increased to 63 (mean 3.15 per patient). These variants classified as pathogenic (n = 31), likely pathogenic (n = 3), and VUS (n = 29) showed a broad range of VAF (0.21–88.84%) and were spread across 25 genes. NGS data help to better stratify 3 AML patients shifting from intermediate to high risk group due to the presence of RUNX1 variants (UPN7, UPN9, UPN11) (Table 2).
To determine the value of molecular NGS-MRD for the discrimination of relapse or non-relapse when MC was detected, only variants classified as pathogenic and likely pathogenic (n = 34) were considered (Table 3). The patient without sample before HSCT (UPN20) with a NGS-MRD variant during the follow-up was also included for molecular relapse associated analysis. The NGS-MRD variants were spread across 16 genes (KRAS, TP53, DNMT3A, FLT3, NPM1, SRSF2, IDH2, NRAS, PTPN11, ASXL1, EZH2, IDH1, PHF6, RUNX1, TET2, U2AF1), and included 27 single-nucleotide variants(SNV) and 7 indels. The most frequent altered genes were KRAS and TP53 (4 patients), DNMT3A, FLT3, NPM1, and SRSF2 (3 patients) (Table 2).
We found that 14 patients had 25 variants in clonal hematopoiesis of indeterminate potential (CHIP)-associated genes (DNMT3A, SRSF2, CUX1, TET2, TP53, UA2F1, ASXL1, SF3B1) [32,33]. Of those, 8 patients harbored more than 1 variant (6 patients with 2 variants, 1 patient with 3 variants, and 1 patient with 4 variants).
These results demonstrate that NGS performed on PB samples is also suitable to characterize the molecular clonal heterogeneity of the myeloid malignancies, and provides useful information to improve the risk stratification of myeloid patients.

3.3. Molecular Variants and Chimerism Dynamics after Allogenic HSCT

Low level of host-DNA can be detected in PB for several months after transplant by high-sensitive indel-qPCR assay. Therefore, to determine the presence of molecular markers in the same PB samples would be useful for the interpretation of these low levels of MC. In our study, kinetics of chimerism and genetic variants detected in 56 samples post-HSCT showed a similar time-course pattern (Table 3). Accordingly to chimerism status, 45 samples had MC and 11 had CC. Specifically, in 31/45 (69%) of the samples with MC, we detected NGS-variants; even with MC values below 5% (15 samples). We did not detect any variants in 14/45 of the samples with MC; 8 of those had MC values below 1%. In addition, within the 11/56 samples with CC, 9 samples (82%) showed no molecular variants (Table 3).
These results indicate that NGS might provide additional useful information to chimerism status data during follow-up after-HSCT.

3.4. NGS-MRD Specificity in PB Samples from Non-Relapsed Patients

In order to establish the specificity of molecular NGS-MRD in PB, we monitored the pathogenic or likely pathogenic variants of 8 patients in remission with different chimerism status for at least 12 months after HSCT (20 samples).
According to chimerism profile, in 6/8 patients, MC decreased until CC was reached (Figure 1), with a mean time of 220 days (range 90–360 days) (Table 3). During MC time, no NGS-MRD variants were detected in 5/6 patients and in 3/6 patients only VUS was present (Table 3). For UPN16, a pathogenic variant detected during MC time disappeared when CC status was achieved, while a VUS in the NF1 gene (VAF ≈ 50%) confirmed in his sibling-donor was detected at all follow-up samples (Table 2, Supplementary Materials Figure S3).
In two non-relapsed patients, we detected an increase of MC after HSCT. In UPN8, although MC was persistent and high (>10% host-DNA), no variant was detected at days 90, 180, and 1135 post-HSCT. Surprisingly, for patient UPN9, despite the fact that relapse had never occurred, we detected an increase of VAF for the variants in the CHIP-associated genes ASXL1 and SRSF2 concomitant to the MC increase (Table 2, Supplementary Materials Figure S4). In summary, NGS-MRD was negative at the last time point tested in 7/8 non-relapsed patients, and in 5 of those, the NGS-MRD status totally correlated with CC.

3.5. NGS-MRD Sensitivity in PB Samples from Relapsed Patients

To assess the sensitivity of NGS-MRD detection in PB samples during post-HSCT follow-up, we tested 36 samples from the relapsed group (12 patients). In 8 patients (67%), positive NGS-MRD correlated with the presence of MC at the time of clinical relapse (Table 3). All variants detected at relapse were already present at diagnosis; and additionally, in UPN1, two new acquired VUS, not present in his HSC donor, were also identified, suggesting clonal evolution and disease progression (Figure 2). In two patients with CC and negative NGS-MRD (UPN2, UPN3), NGS-MRD was detected when slight increase in chimerism was measured (0.67% and 0.12% host-DNA)(Figure 2 and Supplementary Materials Figure S5). Importantly, in 6/8 patients, NGS-MRD was detectable between 20 to 220 days (mean 40 days) before clinical relapse (Table 3, Figure 3 and Supplementary Materials Figure S5).
In 4 relapsed cases, no NGS-MRD was detected: in UPN5 (1.4% host-DNA) and UPN18 (MC > 5%), VUS in GATA2 and CUX1 respectively were detected; in UPN4, early relapse was detected with a low MC value (0.2% host-DNA) and was quickly treated; and in UPN11, NGS-MRD was not detected despite the fact the MC value was high (Supplementary Materials Figure S6).
These results showed that the high specificity of tracking the same NGS variants during HSCT follow up when an increase in MC is detected could help to discriminate early relapse, providing a useful tool for personalized therapeutic intervention.

4. Discussion

The present study aims to investigate the clinical value of post-HSCT NGS-MRD monitoring on serial PB samples in patients with myeloid neoplasms according to chimerism status. Clinical decisions after HSCT, such as lymphocyte donor infusion or removal of immunosuppression, are partially based on chimerism results. Considering that MC can have different clinical implications, including disease relapse, graft failure, and rejection, but may also remain stable for a long time and be compatible with prolonged remission [34], identification of patients who could benefit from an early clinical intervention is necessary. We have focused on patients with low levels of MC in hope that close monitoring and NGS-MRD detection could help to take specific clinical decisions such as better timing for the initiation of antineoplastic treatment.
qPCR is as a sensitive method to detect chimerism and previous studies have established cut-off values or increased MC values as a predictive marker for relapse [35,36,37]. In our cohort, NGS provided useful information to understand clinical status during MC fluctuations and the kinetics of early relapse. Our results suggest that the decision of therapeutic intervention in patients with low levels of MC should be based not only in a defined cut-off value, but also in the individualized chimerism kinetics. For instance, NGS could help to discriminate between MC status with positive NGS-MRD (UPN3) and without positive NGS-MRD (UPN7) (Figure 1 and Figure 2).
Moreover, the use of techniques with higher sensitivity and changes in treatment such as reduced intensity conditioning regimens and T-cell depletion [38] have increased the chances to detect the presence of MC. In our cohort, all patients had MC status after HSCT and the time to achieve CC ranged from 90–600 days, considering 0.01% threshold and 70–240 days with a limit of 0.1%. Therefore, chimerism status needs to be comprehensively interpreted and it is desirable to combine it with an additional method that increases specificity. We have showed the NGS utility in 6 non-relapsed patients where MC was not accompanied with NGS-MRD variants, and in one patient where NGS-MRD variants disappeared when CC was achieved (Figure 1). These findings indicate that the disease course is effectively monitored through combination of both techniques and personalized therapy measures can be implemented if needed.
Different studies showed that the presence of allelic burden by NGS at day 21 post-HSCT can estimate the risk of relapse and mortality, and that NGS-MRD monitoring in PB on days 90 and 180 post-HSCT is predictive for relapse and overall survival [39,40]. Our study has demonstrated that monitoring allelic burden by NGS during the disease course is useful to define molecular relapse, and thus could help to take therapeutic decisions. We detected specific positive NGS-MRD in 67% of the patients with relapse and, importantly, in 6 patients, it was detected between 20 to 220 days before clinical relapse (Table 3).
This finding supports similar results showing positive NGS-MRD in 62% of 58 samples (39 patients) collected 20–80 days prior to relapse [41]. Most NGS panels set their sensitivity around 1% of VAF for SNV variants, implying that NGS would not be a suitable technology for MRD detection. However, we found that detecting the same NGS variants present at diagnosis during the follow up after HSCT was useful for clinicians to raise a red flag and keep a closer monitorization.
Besides, personalized chimerism monitoring revealed that a slight increase of MC (<1%) detected by the high-sensitive indel-qPCR method, not detectable with STR-PCR (sensitivity 1–5%), could identify the accurate timing to perform NGS. Recently, simultaneous variant and single nucleotide polymorphism (SNP) based chimerism NGS study in 14 MDS patients detected an increase of MC and variants in 3 patients with relapse [42]. However, SNP-based chimerism sensitivity is lower than with indel-qPCR, and the cost of several serial samples analysis by NGS will be too high to be implemented in the clinical routine. Similarly, simultaneous molecular and chimerism detection by ddPCR has been demonstrated as a suitable approach for disease monitoring post-HSCT in AML [43]. However, ddPCR limits the number of molecular markers that can be assessed, and new clonal variants indicating progression, like the ones found in UPN1, could be missed.
Importantly, 8 patients had variants in CHIP-associated genes [32] at relapse or the last moment of follow up. Nowadays, these variants are difficult to interpret in the context of the disease progression, so further studies are needed to help to discriminate CHIP variants from clonal disease variants. Besides, it has been previously published that clonal hematopoiesis of donor origin cells may be detected [33]. Altogether, we demonstrate that the evaluation of CHIP variants must be done carefully and that the complete genotyping of donors should be implemented.
Importantly, we have used the same PB DNA samples to analyze chimerism and variant status, showed that they perform similarly to BM DNA, and demonstrated the convenience of combining both methods (Table 3). Therefore, the more accessible PB samples could be used to detect MC increase to determine the precise timing to perform NGS, and allow a cost-benefit use of this technique. Overall, we have defined an approach based on NGS-MRD analysis when slight changes of chimerism in PB samples are observed, combining the high-specificity NGS with high-sensitivity chimerism technology.
Despite the advantages of the proposed approach, our patient cohort was limited and therefore we were not able to establish solid values for sensitivity, specificity, and prediction of relapse. Besides, in few relapsed cases, no NGS-MRD was detected, maybe due to the different sensitivity of the technology among variants types (SNV or INDELS) or the fact that some patients may relapse with variants in genes not included in the panel. Therefore, future studies using larger cohorts with serial samples following HSCT would be needed to further confirm the suitability and sensitivity of NGS during chimerism monitoring.
In summary, NGS offers a deeper understanding on variant dynamics throughout the course of post-HSCT and its clinical relevance. Overall, regardless the reason of relapse, the treatment, or the prognosis, this small series shows that personalized NGS-MRD monitoring in combination with highly-sensitive-chimerism analysis are complementary tools to assess early relapse, providing valuable information to monitor myeloid patients after HSCT.

Supplementary Materials

The following are available online at https://www.mdpi.com/2077-0383/9/12/3818/s1. Figure S1: Flow-chart showing a description of patients and samples selection. Figure S2: Correlation analysis of VAF percentage in peripheral blood and bone marrow-paired samples performed with Pearson correlation test. Figure S3: NGS analysis in non-relapsed patients achieving CC UPN6 (A), UPN10 (B), UPN15 (C), UPN16 (D). Figure S4: NGS analysis in non-relapsed patients with MC. Non-relapsed patients showed negative NGS-MRD despite presence of MC for patients UPN8 (A) and UPN9 (B). Figure S5: Relapsed patients with positive NGS-MRD UPN2 (A), UPN13 (B), UPN14 (C), UPN20 (D). Figure S6: Relapsed patients with no positive NGS-MRD. No NGS-MRD variants were detected at the time of relapse for UPN5 (A), UPN4 (B), UPN11 (C), UPN18 (D).

Author Contributions

Conceptualization, M.F.-M., M.C.V., M.T.Z., I.V., E.B.; methodology, E.B., I.V.; software, B.A.; formal analysis, P.A.-R., Z.B.-I., P.A., A.J.; investigation, P.A.-R., B.A., M.C.V., M.T.Z., Z.B.-I., A.A.-D., A.M., M.J.L., P.A., A.J., M.C.M., M.R.; resources.; M.C.V.; M.T.Z.; M.C.M., M.J.L.; data curation, P.A.-R.; B.A.; writing—original draft preparation, P.A.-R., B.A., E.B., I.V.; writing—review and editing, P.A.-R., M.F.-M., E.B., I.V., F.P.; supervision, M.J.C., F.P., M.C.M., M.R.; project administration, M.F.-M., E.B.; funding acquisition, M.J.C., F.P., M.C.M., M.R. All authors have read and agreed to the published version of the manuscript.

Funding

This work was funded by the Government of Navarra, Department of Industry, Energy and Innovation (Project DIANA, 0011-1411-2017-000028); and supported by CIMA LAB diagnostics research program. F.P. acknowledges funding from Instituto de Salud Carlos III (ISCIII) PI16/02024, PI17/00701 and PI19/01352 (Co-financed with European Union FEDER funds), CIBERONC CB16/12/00489 (Co-financed with European Union FEDER funds), MINECO Explora (RTHALMY), Departamento de Salud-Gobierno de Navarra 40/2016 and Fundación Ramón Areces (PREMAMM).

Acknowledgments

We acknowledge the support given by the CIMA LAB Diagnostics team members. We particularly acknowledge the patients for their participation.

Conflicts of Interest

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

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Figure 1. Specificity of the NGS-MRD analysis in non-relapsed patients. Specific negative NGS-MRD confirms remission during MC decreased until CC is reached in both UPN7 (A) and UPN17 (B). Post-HSCT engraftment analysis by indel-qPCR results are plotted as percentage of receptor (Y-axis) over time shown as days post-HSCT (X-axis). Vertical dotted lines denote the NGS-analysis time points and the height bars represents VAF percentages; asterisk indicate NGS-MRD variants. (NGS = next generation sequencing; MRD = minimal residual disease; MC = mixed chimerism; CC = complete chimerism; HSCT = hematopoietic stem cell transplant; UPN = unique patient number; VAF = variant allele frequency).
Figure 1. Specificity of the NGS-MRD analysis in non-relapsed patients. Specific negative NGS-MRD confirms remission during MC decreased until CC is reached in both UPN7 (A) and UPN17 (B). Post-HSCT engraftment analysis by indel-qPCR results are plotted as percentage of receptor (Y-axis) over time shown as days post-HSCT (X-axis). Vertical dotted lines denote the NGS-analysis time points and the height bars represents VAF percentages; asterisk indicate NGS-MRD variants. (NGS = next generation sequencing; MRD = minimal residual disease; MC = mixed chimerism; CC = complete chimerism; HSCT = hematopoietic stem cell transplant; UPN = unique patient number; VAF = variant allele frequency).
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Figure 2. NGS-MRD markers for relapse detection in patients that achieved complete chimerism. Relapsed patients showed a correlation of chimerism status and NGS-MRD during the monitoring of the disease course; MC increase and NGS-MRD variants were detected prior to clinical relapse. (A) In UPN1, negative NGS-MRD correlated with CC and two new variants were detected with the slight increase of MC even before positive NGS-MRD presence. (B) In UPN3, no complete clearance of all the variants was achieved even during CC, and NGS-MRD turned positive when a slight increase of MC was detected. Post-HSCT engraftment analysis by indel-qPCR results are plotted as percentage of receptor (Y-axis) over time shown as days post-HSCT (X-axis). Vertical dotted lines denote the NGS-analysis time points and the height bars represents VAF percentages; asterisk indicate NGS-MRD variants. (NGS = next generation sequencing; MRD = minimal residual disease; MC = mixed chimerism; CC = complete chimerism; HSCT = hematopoietic stem cell transplant; UPN = unique patient number; VAF = variant allele frequency).
Figure 2. NGS-MRD markers for relapse detection in patients that achieved complete chimerism. Relapsed patients showed a correlation of chimerism status and NGS-MRD during the monitoring of the disease course; MC increase and NGS-MRD variants were detected prior to clinical relapse. (A) In UPN1, negative NGS-MRD correlated with CC and two new variants were detected with the slight increase of MC even before positive NGS-MRD presence. (B) In UPN3, no complete clearance of all the variants was achieved even during CC, and NGS-MRD turned positive when a slight increase of MC was detected. Post-HSCT engraftment analysis by indel-qPCR results are plotted as percentage of receptor (Y-axis) over time shown as days post-HSCT (X-axis). Vertical dotted lines denote the NGS-analysis time points and the height bars represents VAF percentages; asterisk indicate NGS-MRD variants. (NGS = next generation sequencing; MRD = minimal residual disease; MC = mixed chimerism; CC = complete chimerism; HSCT = hematopoietic stem cell transplant; UPN = unique patient number; VAF = variant allele frequency).
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Figure 3. NGS-MRD markers for relapse detection in relapsed patients with MC fluctuations. NGS-MRD during MC monitoring helps to anticipate clinical relapse. Detection of positive NGS-MRD anticipates relapse 220 days in UPN12 (A) and 40 days in UPN19 (B). Post-HSCT engraftment analysis by indel-qPCR results are plotted as percentage of receptor (Y-axis) over time shown as days post-HSCT (X-axis). Vertical dotted lines denote the NGS-analysis time points and the height bars represents VAF percentages; asterisk indicate NGS-MRD variants. (NGS = next generation sequencing; MRD = minimal residual disease; MC = mixed chimerism; CC = complete chimerism; HSCT = hematopoietic stem cell transplant; UPN = unique patient number; VAF = variant allele frequency).
Figure 3. NGS-MRD markers for relapse detection in relapsed patients with MC fluctuations. NGS-MRD during MC monitoring helps to anticipate clinical relapse. Detection of positive NGS-MRD anticipates relapse 220 days in UPN12 (A) and 40 days in UPN19 (B). Post-HSCT engraftment analysis by indel-qPCR results are plotted as percentage of receptor (Y-axis) over time shown as days post-HSCT (X-axis). Vertical dotted lines denote the NGS-analysis time points and the height bars represents VAF percentages; asterisk indicate NGS-MRD variants. (NGS = next generation sequencing; MRD = minimal residual disease; MC = mixed chimerism; CC = complete chimerism; HSCT = hematopoietic stem cell transplant; UPN = unique patient number; VAF = variant allele frequency).
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Table 1. Clinical and therapeutic characteristics of myeloid patients included in this study. Genetic risk was defined by specific scores: ELN for AML, IPPS-R for MDS and CPSS for CMML; pre-transplant disease status was determined by analysis of bone marrow morphology; MRD pre-transplant was determined by flow-cytometry or the presence of a single-molecular marker; and HSCT conditioning regime was selected accordingly to patient fitness.
Table 1. Clinical and therapeutic characteristics of myeloid patients included in this study. Genetic risk was defined by specific scores: ELN for AML, IPPS-R for MDS and CPSS for CMML; pre-transplant disease status was determined by analysis of bone marrow morphology; MRD pre-transplant was determined by flow-cytometry or the presence of a single-molecular marker; and HSCT conditioning regime was selected accordingly to patient fitness.
UPNSexAge at HSCTDiagnosisAML/MDS DiagnosisGenetic RiskClassical Genetic MarkersNGS Genetic Markers Pre-HSCTPre-HSCT Disease StatusMRD Pre-HSCT StatusDays from Diagnosis to HSCTHSCT Conditioning RegimenImmunosupression TreatmentHLA Antigen MatchChimerism Profile after HSCTChimerism Profile at RelapseClinical Outcome
1M18JMMLde novointermediate46,XY (3 0)NRAS-p.Gln61LysCR1positive137MA (BuCy)FK506 + MTX + ATGfully matched unrelated donorCCMCrelapse
2F66AMLde novointermediate46,XX,t (4;12)(q12;p13)(14)/46,XX(16)
FLT3-ITD(-)
IDH2-p.Arg172Lys
NF1-p.Ile1603Val
DNMT3A-p.Val895Met
DNMT3A-p.Arg729Gln
CR1positive188RIC (FLU + BU2)FK506 + MTXfully matched unrelated donorCCMCrelapse
3F70AMLSecondaryadverse46,XX,del(5q)(22/25)/46,XX(3/25)TP53-p.Arg273Cys
NRAS-p.Gly13Asp
SH2B3-p.?
Not CRpositive231RIC (FLU + BU2)FK506 + MTXfully matched sibling donorCCMCrelapse
5F65AMLde novoadversehypodiploid complex karyotypeTP53-p.Val173Met
GATA2-p.Gly149Arg
CR1positive121RIC (FLU + BU2)CS + MTXfully matched sibling donorCCMCrelapse
4F61AMLSecondaryadverse47,XX,-3,del(5)(q13q33),+8,-17,+21,+21(6)/48,idem,+20(3)/46,XX(7)TP53-p.?
ETV6-p.Arg291Glyfs*25
CR1positive144RIC (FLU + BU2)FK506 + MTX + ATGsingle antigen mismatch unrelated donorMCMCrelapse
11M37AMLde novointermediate46,XY(25)PTPN11-p.Gly503Glu
RUNX1-p.?
CR1ND129MA (BuCy)CS + MTX + CAMPATHfully matched unrelated donorMCMCrelapse
12M69MDSSecondaryadversetrisomy 8 and monosomy 7DNMT3A-p.Arg326Cys
U2AF1-p.Ser34Phe
CR1ND177RIC (FLU + BU2)CS + MTX + CAMPATHfully matched unrelated donorMCMCrelapse
13F57MDSde novoadverse45,XX,-7(4)/45,X,-X(3)/46,XX(13)KRAS-p.Gly12CysNot CRpositive259MA (FLU + BU4)FK506 + MTXfully matched unrelated donorMCMCrelapse
14F59AMLde novointermediate47,XX,+4(5/20)/46,XX(15/20)FLT3-p.Val592Ala
NPM1-p.Trp288Cysfs*12
DNMT3A-p.Arg882His
KRAS-p.Gly12Asp
KMT2A-p.Gln147Arg
CR1negative161RIC (FLU + BU2)FK506 + MTXfully matched sibling donorMCMCrelapse
18F56MDSSecondaryadverse46,XX,inv(3)(q21q26)(20)PHF6-p.Arg274Ter
SF3B1-p.Ala708Pro
CUX1-p.Arg554Gln
CR1positive155RIC (FLU + BU2)FK506 + MTXfully matched sibling donorMCMCrelapse
19M59CMMLde novointermediate45,X,-Y(1)/46,XY(3)KRAS-p.Ala18Asp
TET2-p.Gln764Profs*5
EZH2-p.Arg679Cys
CUX1-p.?
SRSF2-p.Ser54Phe
TET2-p.Ser1853Argfs*35
Not CRND1750RIC (FLU + BU2)FK506 + MTXfully matched sibling donorMCMCrelapse
20F62MDSde novoadverse47,XX,+8(17/20)/46,XX(3/20)NDCR1negative239RIC (FLU + BU2)FK506 + MTXfully matched sibling donorMCMCrelapse
6F45AMLde novoadverse46,XX(13)
FLT3-ITD(+)
FLT3-ITD-p.Tyr597_Glu611dup
NPM1-p.Trp288Cysfs*12
DNMT3A-p.Leu639Serfs*12
CR1positive138MA (BuCy)FK506 + MTX + ATGfully matched unrelated donorCC-remission
7F42AMLde novointermediate46,XX(24/25)/47,XX,+8(1/25])
nuc ish(D8Z2x3)(87/145)
IDH2-p.Arg172Lys
SH2B3-p.Ser213Arg
RUNX1-p.Ser390Profs*?
CR1positive136MA (BuCy)FK506 + MTXfully matched sibling donorCC-remission
10M39AMLde novoadverse46,XY,t(3;3)(q21;q26)
FLT3-ITD(+)
FLT3-ITD-p.Asp586_Glu598dup
NPM1-p.Trp288Cysfs*12
CUX1-p.Arg219Gln
GATA2-p.Gly135Trpfs*50
CR1negative170MA (FLU + BU4)FK506 + MTXfully matched sibling donorCC-remission
15F61AMLSecondaryadverse45,XX,-7(6/20)/46,XX(14/20)DNMT3A-p.Arg882His
IDH1-p.Arg132Cys
DNMT3A-p.Phe868Ser
CR1ND159RIC (FLU + BU2)FK506 + MTXfully matched sibling donorCC-remission
16M39MDSde novoadverse46,XYY,t(2;11)(q32;q13)?,-5,t(7;16)(q31;q22)?,del(20q)(7)/47,XYY(4)TP53-p.Arg267Trp
RUNX1-p.Arg139Gln
SRSF2-p.Pro95Leu
NF1-p.Leu380Phe
Not CRpositive262MA (FLU + BU4)FK506 + MTXfully matched sibling donorCC-remission
17M41MDSde novoadverse46,XY,del(12p)(7)/46,XY(18)U2AF1-p.Ser34Phe
CALR-p.Glu380Gly
Not CRpositive88MA (BuCy)CS + MTXfully matched sibling donorCC-remission
8F56AMLde novoadverse47,XX,+8,t(5;9;11;13)(q33;p22;q23;q13)KRAS-p.Gly13Asp
PTPN11-p.Ala72Thr
CR1negative161RIC (FLU + BU2)CS + MTX + CAMPATHsingle antigen mismatch unrelated donorMC-remission
9M68AMLde novointermediate46,XY(20)ASXL1-p.Gly646Trpfs*12
SRSF2-p.Pro95His
KMT2A-p.Leu989Phe
NF1-p.Leu2714Val
RUNX1-p.Asn82Asp
CR1ND162RIC (FLU + BU2)CS + MTX + CAMPATHfully matched unrelated donorMC-remission
UPN = unique patient number; M = male; F = female; AML = acute myeloid leukemia; MDS = myelodysplastic syndrome; JMML = juvenile myelomonocytic leukemia; CMML = chronic myelomonocytic leukemia; MRD = minimal residual disease; ELN = European LeukemiaNet; IPPS-R = Revised International Prognostic Scoring System; CPSS = CMML-specific prognostic scoring system; ND = not determined; CR, complete response; HSCT = hematopoietic stem cell transplant; MA = myeloablative; RIC = reduced intensity conditioning; BuCy = busulfan-cyclophosphamide; FLU = fludarabine; BU2 = busulfan 2 days; BU4 = busulfan 4 days; FK506 = tacrolimus; MTX = methotrexate; ATG = antithymocyte globulin; CS = cyclosporin A; CC = complete chimerism; MC = mixed chimerism.
Table 2. NGS variants identified in the 20 patients during the disease time course. Information of the variants detected with the pan-myeloid panel includes VAF percentage and sequencing depth for all time points. For variants with VAF below 1% results from VarScan (SNV) and Mutect2 (indels) in-house analysis are plotted.
Table 2. NGS variants identified in the 20 patients during the disease time course. Information of the variants detected with the pan-myeloid panel includes VAF percentage and sequencing depth for all time points. For variants with VAF below 1% results from VarScan (SNV) and Mutect2 (indels) in-house analysis are plotted.
UPNGeneChrPositionConsequencec.DNAProteinClassificationDiagnosisPost-TMPost-HSCT 1Post-HSCT 2Post-HSCT 3Post-HSCT 4Post-HSCT 5RelapsePost-Relapse
1NRAS1115256530missensec.181C > Ap.Gln61LysPathogenic45.38%
8951x
-NDNDND12%
6457x
-14.07%
5872x
-
WT11132417914frameshiftc.1086dupAp.Arg363Thrfs*5Uncertain significanceNDNDNDND10%
7688x
13%
7444x
WT11132417910frameshiftc.1077_1090dupGACTCTTGTACGGTp.Ser364TerUncertain significanceNDNDND0.21%
6200x
9%
7694x
13%
7400x
2IDH21590631838missensec.515G > Ap.Arg172LysPathogenic13.91%
4667x
-NDND---0.40%
3716x
1.62%
5002x
NF11729652872missensec.4807A > Gp.Ile1603ValUncertain significance48.96%
3619x
NDND0.42%
3352x
1.60%
4634x
DNMT3A225457204missensec.2683G > Ap.Val895MetUncertain significance12.61%
5688x
NDND0.47%
4510x
1.81%
5967x
DNMT3A225463307missensec.2186G > Ap.Arg729GlnUncertain significance12.04%
6036x
NDND0.37%
4884x
1.41%
6183x
3TP53177577121missensec.817C > Tp.Arg273CysPathogenic19.97%
3445x
-NDND0.58%
5165x
--4.03%
6688x
-
NRAS1115258744missensec.38G > Ap.Gly13AspPathogenic4.20%
4020x
NDNDNDND
SH2B312111885351splice sitec.1236 + 3A > Gp.?Uncertain significance2.97%
3810x
4.99%
3810x
1.43%
4186x
1.48%
4987x
3.67%
4792x
5TP53177578413missensec.517G > Ap.Val173MetPathogenic1.32%
7719x
-0.32%
4999x
ND---ND-
GATA23128204996missensec.445G > Ap.Gly149ArgUncertain significance51.46%
6528x
4.32%
6246x
ND0.68%
3691x
4TP53177578370splice sitec.559 + 1G > Ap.?Pathogenic28.94%
7888x
-NDND---NDND
ETV61212022762frameshiftc.870delCp.Arg291Glyfs*25Uncertain significance17.69%
8934x
NDNDNDND
11PTPN1112112926888missensec.1508G > Ap.Gly503GluPathogenic32.91%
5585x
-ND----ND-
RUNX12136252852splice sitec.427 + 2T > Cp.?Uncertain significance35.04%
1096x
NDND
12DNMT3A225470498missensec.976C > Tp.Arg326CysLikely pathogenic7.12%
5648x
-0.79%
2341x
0.30%
7718x
---0.48%
2935x
-
U2AF12144524456missensec.101C > Tp.Ser34PhePathogenic5.35%
5363x
NDNDND
13KRAS1225398285missensec.34G > Tp.Gly12CysPathogenic7.54%
2919x
-ND0.58%
1733x
---2.38%
3237x
-
14FLT31328608281missensec.1775T > Cp.Val592AlaPathogenic23.42%
3151x
------NDND
NPM1 Type A5170837543frameshiftc.860_863dupTCTGp.Trp288Cysfs*12Pathogenic15.27%
1821x
NDND
DNMT3A225457242missensec.2645G > Ap.Arg882HisPathogenic36.24%
3797x
2.22%
2832x
2.07%
13045x
KRAS1225398284missensec.35G > Ap.Gly12AspPathogenic1.94%
2167x
NDND
KMT2A11118339497missensec.440A > Gp.Gln147ArgUncertain significance28.84%
2691x
NDND
18PHF6X133549136stop codonc.820C > Tp.Arg274TerLikely pathogenic12.74%
2834x
-ND----ND-
SF3B12198266810missensec.2122G > Cp.Ala708ProUncertain significance17.97%
3016x
NDND
CUX17101923357missensec.1661G > Ap.Arg554GlnUncertain significance49.19%
3015x
3.27%
6597x
3.31%
2446x
19KRAS1225398266missensec.53C > Ap.Ala18AspPathogenic41.46%
2383x
-1.69%
5756x
----10.82%
1303x
-
TET24106157384frameshiftc.2290dupCp.Gln764Profs*5Pathogenic39.64%
3042x
1.71%
8269x
16.83%
2400x
EZH27148506462missensec.2035C > Tp.Arg679CysLikely pathogenic84.49%
2243x
3.28%
6309x
34.12%
1603x
CUX17101713618splice sitec.223-1G > Tp.?Uncertain significance88.84%
1945x
2.36%
4997x
39.76%
1484x
SRSF21774733082missensec.161C > Tp.Ser54PheUncertain significance43.34%
2469x
1.65%
10315x
18.52%
2921x
TET24106197221frameshiftc.5557_5558dupp.Ser1853Argfs*35Uncertain significance41.81%
3449x
1.49%
9252x
19.31%
3729x
20SRSF21774732959missensec.284C > Gp.Pro95ArgPathogenic--9.07%
11465x
----42.72%
11317x
-
CUX17101848405missensec.3118G > Ap.Val1040MetUncertain significance15.12%
4187x
42.32%
3852x
TET24106190851missensec.4129T > Gp.Phe1377ValUncertain significance10.52%
6340x
74.32%
5947x
RUNX12136259163missensec.247A > Cp.Lys83GlnUncertain significance1.41%
3757x
5.83%
4271x
6FLT3-ITD1328608223inframec.1788_1832dupp.Tyr597_Glu611dupPathogenic51%
6880x
-NDNDND----
NPM1 Type A5170837543frameshiftc.860_863dupTCTGp.Trp288Cysfs*12Pathogenic36.09%
3497x
NDNDND
DNMT3A225466788frameshiftc.1914delTp.Leu639Serfs*12Uncertain significance43.80%
7175x
NDNDND
7IDH21590631838missensec.515G > Ap.Arg172LysPathogenic16.09%
6232x
-NDND-----
SH2B312111856588missensec.639C > Ap.Ser213ArgUncertain significance47.90%
5635x
0.79%
2404x
ND
RUNX12136164626frameshiftc.1167delCp.Ser390Profs*?Uncertain significance15.24%
4613x
NDND
10FLT3-ITD1328608261inframec.1756_1794dup39p.Asp586_Glu598dupPathogenic43%
4503x
-NDND-----
NPM1 Type D5170837544frameshiftc.863_864i-CCTGp.Trp288Cysfs*12Pathogenic36.74%
2730x
NDND
CUX17101758502missensec.656G > Ap.Arg219GlnUncertain significance47.41%
3634x
1.19%
2010x
ND
GATA23128205042frameshiftc.399_430p.Gly135Trpfs*50Uncertain significance45.04%
4043x
NDND
15DNMT3A225457242missensec.2645G > Ap.Arg882HisPathogenic10.33%
6246x
-ND------
IDH12209113113missensec.394C > Tp.Arg132CysPathogenic3.82%
5495x
ND
DNMT3A225457284missensec.2603T > Cp.Phe868SerUncertain significance5.53%
6092x
ND
16TP53177577139missensec.799C > Tp.Arg267TrpPathogenic51.86%
3922x
-1.72%
7751x
ND-----
RUNX12136252865missensec.416G > Ap.Arg139GlnPathogenic12.11%
1024x
NDND
SRSF21774732959missensec.284C > Tp.Pro95LeuPathogenic5.40%
3539x
NDND
NF11729528130missensec.1138C > Tp.Leu380PheUncertain significance35.46%
2033x
44%
3011x
51%
1413x
17U2AF12144524456missensec.101C > Tp.Ser34PhePathogenic25.20%
3012x
-NDND-----
CALR1913054612missensec.1139A > Gp.Glu380GlyUncertain significance51.90%
3703x
1.22%
3865x
ND
8KRAS1225398281missensec.38G > Ap.Gly13AspPathogenic38.32%
5128x
-NDNDND----
PTPN1112112888198missensec.214G > Ap.Ala72ThrPathogenic4.63%
6042x
NDNDND
9ASXL12031022441frameshiftc.1934dupGp.Gly646Trpfs*12Pathogenic-1.40%
6069x
1.49%
3293x
1.61%
2231x
1.62%
3769x
7.18%
5675x
16%
14672x
--
SRSF21774732959missensec.284C > Ap.Pro95HisPathogenic1.21%6677xNDND1.12%3479x7.11%4879x16.52%15740x
KMT2A11118344839missensec.2965C > Tp.Leu989PheUncertain significance48.66%6178xND0.69%2036x1.61%5476x6.87%4539x12%4007x
NF11729687547missensec.8140C > Gp.Leu2714ValUncertain significance49.82%5221xNDND1.87%4547x5.71%4117x8.50%3624x
RUNX12136259166missensec.244A > Gp.Asn82AspUncertain significance0.97%3005xNDND0.69%2188x6.27%3143x11.85%5427x
UPN = unique patient number; Chr = chromosome; TM = treatment; HSCT = hematopoietic stem cell transplantation; ND = not detected; hyphen (-) = NGS analysis not performed.
Table 3. Correlation between chimerism and presence of molecular variants for the 20 HSCT patients. Results show the percentage of chimerism in total peripheral blood and the presence of molecular markers detected by NGS for all time points during the disease course.
Table 3. Correlation between chimerism and presence of molecular variants for the 20 HSCT patients. Results show the percentage of chimerism in total peripheral blood and the presence of molecular markers detected by NGS for all time points during the disease course.
UPNDiagnosisPatient GroupMoment of SampleDays after HSCT% ChimerismNGS-Trackable
Variants 1
NGS-MRD
Variants 2
1JMMLRelapseBefore HSCT--PositivePositive
Post-HSCT1000.95%NegativeNegative
Post-HSCT600<0.01%NegativeNegative
Post-HSCT8500.3%PositiveNegative
Post-HSCT95012%PositivePositive
Relapse98564%PositivePositive
2AMLRelapseBefore HSCT--PositivePositive
Post-HSCT250<0.01%NegativeNegative
Post-HSCT3600.09%NegativeNegative
Relapse3800.67%PositivePositive
Post-Relapse4002.24%PositivePositive
3AMLRelapseBefore HSCT--PositivePositive
Post-HSCT906.87%PositiveNegative
Post-HSCT580<0.01%PositiveNegative
Post-HSCT6500.12%PositivePositive
Relapse6907.7%PositivePositive
5AMLRelapseBefore HSCT--PositivePositive
Post-HSCT906.8%PositivePositive
Post-HSCT540<0.01%NegativeNegative
Relapse13501.41%PositiveNegative
4AMLRelapseBefore HSCT--PositivePositive
Post-HSCT1000.1%NegativeNegative
Post-HSCT3000.12%NegativeNegative
Relapse4100.2%NegativeNegative
Post-Relapse4700.34%NegativeNegative
11AMLRelapseBefore HSCT--PositivePositive
Post-HSCT10019%NegativeNegative
Relapse13067%NegativeNegative
12MDSRelapseBefore HSCT--PositivePositive
Post-HSCT6003.3%PositivePositive
Post-HSCT7202.7%PositivePositive
Relapse8202.85%PositivePositive
13MDSRelapseBefore HSCT--PositivePositive
Post-HSCT453.6%NegativeNegative
Post-HSCT805.2%PositivePositive
Relapse10011.6%PositivePositive
14AMLRelapseBefore HSCT--PositivePositive
Relapse605.5%PositivePositive
Post-Relapse140<0.01%PositivePositive
18MDSRelapseBefore HSCT--PositivePositive
Post-HSCT906.2%PositiveNegative
Relapse1805.5%PositiveNegative
19MDSRelapseBefore HSCT--PositivePositive
Post-HSCT806.7%PositivePositive
Relapse12019%PositivePositive
20MDSRelapseBefore HSCT--NANA
Post-HSCT9029%PositivePositive
Relapse130100%PositivePositive
6AMLRemissionBefore HSCT--PositivePositive
Post-HSCT900.02%NegativeNegative
Post-HSCT3000.01%NegativeNegative
Post-HSCT820<0.01%NegativeNegative
7AMLRemissionBefore HSCT--PositivePositive
Post-HSCT901.02%PositiveNegative
Post-HSCT420<0.01%NegativeNegative
10AMLRemissionBefore HSCT--PositivePositive
Post-HSCT1101.79%PositiveNegative
Post-HSCT170<0.01%NegativeNegative
15AMLRemissionBefore HSCT--PositivePositive
Post-HSCT600.85%NegativeNegative
16MDSRemissionBefore HSCT--PositivePositive
Post-HSCT903.85%PositivePositive
Post-HSCT360<0.01%NegativeNegative
17MDSRemissionBefore HSCT--PositivePositive
Post-HSCT301.6%PositiveNegative
Post-HSCT160<0.01%NegativeNegative
8AMLRemissionBefore HSCT--PositivePositive
Post-HSCT9015.4%NegativeNegative
Post-HSCT20014.9%NegativeNegative
Post-HSCT114033%NegativeNegative
9AMLRemissionBefore HSCT--PositivePositive
Post-HSCT1000.21%PositivePositive
Post-HSCT3701.7%PositivePositive
Post-HSCT12502%PositivePositive
Post-HSCT136010%PositivePositive
Post-HSCT155026%PositivePositive
1 NGS-trackable variants: including variants classified as pathogenic, likely pathogenic, or VUS. 2 NGS-MRD variants: including variants classified as pathogenic or likely pathogenic. UPN = unique patient number; HSCT = hematopoietic stem cell transplant; NGS = next generation sequencing; VUS= variant of unknown significance; MRD = minimal residual disease; NA = not available; Hyphen= not performed (Chimerism assay is done after HSCT).
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MDPI and ACS Style

Aguirre-Ruiz, P.; Ariceta, B.; Viguria, M.C.; Zudaire, M.T.; Blasco-Iturri, Z.; Arnedo, P.; Aguilera-Diaz, A.; Jauregui, A.; Mañú, A.; Prosper, F.; et al. Assessment of Minimal Residual Disease by Next Generation Sequencing in Peripheral Blood as a Complementary Tool for Personalized Transplant Monitoring in Myeloid Neoplasms. J. Clin. Med. 2020, 9, 3818. https://doi.org/10.3390/jcm9123818

AMA Style

Aguirre-Ruiz P, Ariceta B, Viguria MC, Zudaire MT, Blasco-Iturri Z, Arnedo P, Aguilera-Diaz A, Jauregui A, Mañú A, Prosper F, et al. Assessment of Minimal Residual Disease by Next Generation Sequencing in Peripheral Blood as a Complementary Tool for Personalized Transplant Monitoring in Myeloid Neoplasms. Journal of Clinical Medicine. 2020; 9(12):3818. https://doi.org/10.3390/jcm9123818

Chicago/Turabian Style

Aguirre-Ruiz, Paula, Beñat Ariceta, María Cruz Viguria, María Teresa Zudaire, Zuriñe Blasco-Iturri, Patricia Arnedo, Almudena Aguilera-Diaz, Axier Jauregui, Amagoia Mañú, Felipe Prosper, and et al. 2020. "Assessment of Minimal Residual Disease by Next Generation Sequencing in Peripheral Blood as a Complementary Tool for Personalized Transplant Monitoring in Myeloid Neoplasms" Journal of Clinical Medicine 9, no. 12: 3818. https://doi.org/10.3390/jcm9123818

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