Analysis of minimal residual disease by Ig/TCR gene rearrangements: guidelines for interpretation of real-time quantitative PCR data

Detection of minimal residual disease in cryopreserved testicular tissue from (pre)pubertal boys with acute leukemia following first-line therapy

STUDY QUESTION

Is it feasible to detect minimal residual disease (MRD) in cryopreserved testicular tissue (TT) from (pre)pubertal boys diagnosed with acute leukemia using molecular biology techniques?

SUMMARY ANSWER

This pilot study demonstrates the feasibility of detecting MRD in cryopreserved TT, which could guide the choice of the safest techniques for fertility restoration.

WHAT IS KNOWN ALREADY

Fertility preservation through testicular tissue freezing (TTF) is offered to (pre)pubertal boys undergoing highly gonadotoxic treatment. However, the risk of reintroducing leukemic cells during fertility restoration has not been adequately addressed. To date, no study has evaluated the feasibility of detecting residual disease using molecular biology within cryopreserved, thawed and unfixed TT.

STUDY DESIGN, SIZE, DURATION

This pilot study analyzed cryopreserved TT from 14 (pre)pubertal boys diagnosed with acute lymphoblastic leukemia (ALL) or acute myeloblastic leukemia (AML) who had already received first-line chemotherapy and underwent TTF before hematopoietic stem cell transplantation.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study included cryopreserved TT from 14 (pre)pubertal boys. Molecular biology techniques, including RT-qPCR and qPCR, were used to detect oncogenic fusion genes or clonal rearrangements of immunoglobulin genes or T-cell receptor (Ig/TCR) in cryopreserved TT samples.

MAIN RESULTS AND THE ROLE OF CHANCE

MRD was identified in 36% (5 out of 14) of TT samples using molecular biology techniques. A 21% discordance was observed between conventional histopathology and molecular detection, with molecular methods showing higher sensitivity. No significant association was found between clinical or histological characteristics and MRD status in the TT.

LIMITATIONS, REASONS FOR CAUTION

This study is a pilot study with a small sample size of TT samples from patients with ALL or AML, which may limit the generalizability of the findings. Further studies with larger cohorts are needed to validate our data.

WIDER IMPLICATIONS OF THE FINDINGS

The detection of MRD in cryopreserved TT using molecular biology techniques could help guide the selection of the safest fertility restoration strategies for leukemic patients by minimizing the risk of reintroducing malignant cells. This approach underscores the importance of cryopreserving TT after complete remission of acute leukemia (AL).

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by Rouen University Hospital, GIRCI NO, French Biomedicine Agency, and Ligue National Contre le Cancer. The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

Not applicable.

NGS-MRD negativity in post-HSCT ALL spares unnecessary therapeutic interventions triggered by borderline qPCR results without an increase in relapse risk

Monitoring of minimal residual disease (MRD) after hematopoietic stem cell transplantation (HSCT) in patients with acute lymphoblastic leukemia (ALL) is vital for timely therapeutic intervention planning. However, interpreting low-positive results from the current standard method, quantitative PCR (qPCR) of immunoglobulin and T-cell receptor gene rearrangements (IG/TR), poses challenges due to the risk of false positivity caused by non-specific amplification. We aimed to improve MRD detection specificity using the next-generation amplicon sequencing (NGS) of IG/TR rearrangements for better relapse prediction. In pediatric and young adult ALL patients undergoing sequential post-HSCT MRD monitoring, we prospectively re-tested positive non-quantifiable qPCR results with NGS-MRD using the EuroClonality-NGS approach. We were able to confirm 13 out of 47 (27.7%) qPCR positive results using the more specific NGS-MRD method. Out of 10 patients with at least one MRD positivity confirmed by NGS, six relapsed (60%) 1-3.7 months after testing. Among 25 patients with all NGS-MRD results negative, two relapses occurred (8%) after 5.1 and 12.1 months. One-year RFS was 40% versus 96% and 3-year OS was 33.3% versus 94.4% for the NGS-positive and NGS-negative groups, respectively. The difference was not attributable to a varying rate of therapeutic interventions. Six patients out of 14 who had immunosuppressive treatment tapered or received donor lymphocyte infusion in response to MRD positivity developed significant graft versus host disease, leading to one fatality. This underscores the importance of enhancing the post-HSCT relapse risk prediction accuracy through NGS-MRD testing to avoid unnecessary interventions.

JCCG ALL-B12: Evaluation of Intensified Therapies With Vincristine/Dexamethasone Pulses and Asparaginase and Augmented High-Dose Methotrexate for Pediatric B-ALL

PURPOSE

The JCCG ALL-B12 clinical trial aimed to evaluate the effectiveness of unvalidated treatment phases for pediatric ALL and develop a safety-focused treatment framework.

PATIENTS AND METHODS

Patients age 1-19 years with newly diagnosed B-ALL were enrolled in this study. These patients were stratified into standard-risk (SR), intermediate-risk (IR), and high-risk (HR) groups. Randomized comparisons assessed the effectiveness of vincristine (VCR)/dexamethasone pulses in the SR group, evaluated the effects of L-asparaginase (ASP) intensification in the IR group, and compared standard consolidation including block-type treatment with experimental consolidation with high-dose methotrexate (HD-MTX) intensified with VCR and ASP in the HR group.

RESULTS

Of 1,936 patients enrolled, 1,804 were eligible for the experimental treatment. The overall 5-year event-free survival and overall survival rates were 85.2% (95% CI, 83.5 to 86.8) and 94.3% (95% CI, 93.1 to 95.3), respectively. The cumulative incidence of relapse and postremission nonrelapse mortality was 13.2% (95% CI, 11.6 to 14.8) and 0.6% (95% CI, 0.3 to 1.0), respectively. Random assignment in the SR group showed no significant benefit from pulse therapy. In the IR group, ASP intensification had limited effects. In the HR group, standard block therapy and HD-MTX yielded equivalent outcomes.

CONCLUSION

The ALL-B12 trial achieved favorable outcomes in a nationwide cohort by stratifying treatment on the basis of risk and balancing treatment intensity. This study not only demonstrated that existing standard of care can be further refined but also indicated that improvement in outcomes with intensified chemotherapy has reached a plateau.

Presence of minimal residual disease determined by next-generation sequencing is not a reliable prognostic biomarker in children with acute lymphoblastic leukemia

The role of next-generation sequencing (NGS) for minimal residual disease (MRD) assessment in pediatric acute lymphoblastic leukemia (ALL) is still under consideration. Fifty pediatric patients were prospectively evaluated for specific clonal rearrangements of immunoglobulin and T-cell receptor genes using NGS analysis at diagnosis and on days 33 and 78 from therapy onset. The prognostic value or the NGS-MRD status was analyzed after a median follow-up of 4 years. All but one patient with negative NGS-MRD status on day 33 are in clinical remission. A total of 29 (58%) patients were NGS-MRD positive on day 33, of which 9 (18%) patients remained positive on day 78. However, only a small percentage of the patients with positive NGS-MRD status on day 33 and day 78 relapsed: 21% (6/29) and 33% (3/9), respectively. Positive NGS-MRD status is not a reliable prognostic biomarker in children with ALL and warrants careful consideration in disease stratification.

[Current situation and prospect of minimal residual disease in pediatric T cell acute lymphoblastic leukemia]

Pediatric T-cell acute lymphoblastic leukemia (T-ALL) has been attracted much attention due to its high aggressiveness and complexity of treatment. Recently, with the development of technology and clinical research, the curative effect of T-ALL in children has been significantly improved. However, the presence of minimal residual disease (MRD) is still a key factor affecting the outcomes of children with T-ALL. With the continuous development of detection methods, the clinical applications of real-time quantitative PCR, multi-parameter flow cytometry, and high-throughput sequencing technology, MRD can be detected accurately to achieve personalized and precise treatment for each patient. The purpose of this article is to review the current detection methods of MRD in T-ALL, the clinical significance of MRD monitoring and evaluation in multi-agent combined chemotherapy and hematopoietic stem cell transplantation, and applying MRD to measure the responsiveness and effectiveness of new therapies in recent T-ALLs. Research directions and potential treatment strategies in the near future were also proposed.

Flow Cytometric MRD Detection in Selected Mature B-Cell Malignancies

The quantification of submicroscopic minimal residual disease (MRD) after therapy proved to have independent prognostic significance in many mature B-cell malignancies. With the advent of routine benchtop cytometers capable of simultaneously analyzing ≥8 colors and with improved standardization, flow cytometry has become the method of choice for MRD assessments in some lymphoma entities. Herein we describe general aspects of flow cytometric standardization. Chronic lymphocytic leukemia (CLL) and multiple myeloma (MM) are used as examples to explain the technical standardization of flow cytometry for MRD detection according to EuroFlow strategies. MRD data acquisition and detailed analysis in MM and CLL is a particular focus of this chapter.

MRD Detection in B-Cell Non-Hodgkin Lymphomas Using Ig Gene Rearrangements and Chromosomal Translocations as Targets for Real-Time Quantitative PCR and ddPCR

Minimal residual disease (MRD) diagnostics is of high clinical relevance in patients with indolent B-cell non-Hodgkin lymphomas (B-NHL), B-cell chronic lymphocytic leukemia (CLL), and multiple myeloma and serves as a surrogate parameter to evaluate treatment effectiveness and long-term prognosis. Real-time quantitative PCR (RQ-PCR) targeting circulating lymphoma cells is still the gold standard for MRD detection in indolent B-NHL and currently the most sensitive and the most broadly applied method in follicular lymphoma (FL) and mantle cell lymphoma (MCL). Alternatively, droplet digital PCR (ddPCR) can be used for MRD monitoring in multiple myeloma, mantle cell lymphoma, CLL, and FL with comparable sensitivity, accuracy, and reproducibility.The most broadly applicable MRD target in B-NHL is the junctional regions of the rearranged immunoglobulin heavy (IGH) and light chain genes. Complete and incomplete IGH and additionally IG kappa light chain rearrangements can be used as targets for MRD. Next-generation sequencing (NGS) of IG-rearrangements (IG-NGS) as new sequencing-based technology can overcome the limitation of PCR-based approaches and has a potential for higher sensitivity. Chromosomal translocations like the t(14;18)(q32;q21) translocation associated with IGH::BCL2 fusion in FL and t(11;14)(q13;q32) translocation in MCL leading to the IGH::CCND1 fusion can be used as MRD target in selected lymphoma subtypes. In patients with CLL, both flow-cytometry and RQ-PCR are equally suited for MRD assessment as long as a sensitivity of 10-4 is achieved.MRD diagnostics targeting the IG loci is complex and requires extensive knowledge and experience because the junctional regions of each clonal rearranged gene have to be identified before the patient-specific PCR assays can be designed for MRD monitoring. In addition, the presence and load of somatic hypermutation within the rearranged IGH gene occurring during B-cell development of germinal center and post-germinal center B-cell lymphomas may hamper appropriate primer binding leading to false-negative results. The translocations mentioned above have the advantage that consensus forward primers and probes, both placed in the breakpoint regions of chromosome 18 in FL and chromosome 11 in MCL, can be used in combination with a reverse primer placed in the IGH joining region of chromosome 14. PCR-based methods using allele-specific primers can reach a high sensitivity of up to 10-5. This chapter provides all relevant background information and technical aspects for the complete laboratory process from detection of the clonal IG gene rearrangements and the chromosomal translocations at diagnosis to the actual MRD measurements in clinical follow-up samples of B-NHL. However, it should be noted that MRD diagnostics for clinical treatment protocols has to be accompanied by regular international quality control rounds to ensure the reproducibility and reliability of the MRD results. This is available by the EuroMRD network ( https://euromrd.org ), a subgroup of ESHLO ( https://eslho.org ).

Outcomes in children with first-relapsed acute lymphoblastic leukemia in Japan: Results from JCCG Study JPLSG-ALL-R08

BACKGROUND/OBJECTIVES

The Berlin-Frankfurt-Münster (BFM)-S classification is a crucial prognostic indicator in children experiencing first-relapsed acute lymphoblastic leukemia (ALL). Early molecular response to therapy, evaluated by measurable/minimal residual disease (MRD), has a significant impact on the survival of patients with childhood ALL. Applying risk stratification based on the BFM-S classification and MRD response after induction, the first nationwide prospective multicenter study, ALL-R08, was conducted in children with first-relapsed ALL in Japan.

METHODS

The ALL-R08 study comprised two parts: ALL-R08-I, an observational study aimed at obtaining an overall picture of outcomes in first-relapsed childhood ALL, and ALL-R08-II, a clinical trial for the non-T-ALL S2 risk group. In ALL-R08-II, patients with an MRD level of ≥10-3 at the end of induction therapy were assigned to undergo allogeneic hematopoietic stem cell transplantation (allo-HCT), whereas those with an MRD level less than 10-3 and isolated extramedullary relapse continued to receive chemotherapy.

RESULTS

In total, 163 patients were enrolled in the ALL-R08 study, and 82 and 81 patients were enrolled in the ALL-R08-I and the ALL-R08-II, respectively. In ALL-R08-I, the probability of 3-year event-free survival (EFS) for patients with S1, S2, S3, S4, and post-HCT groups was 83% ± 15%, 37% ± 11%, 28% ± 8%, 14% ± 7%, and 0%, respectively. In the ALL-R08-II trial, 3-year EFS in patients with post-induction MRD less than 10-3 and ≥10-3 was 70% ± 9% (n = 27) and 68% ± 8% (n = 31) (p = .591), respectively.

CONCLUSIONS

ALL-REZ BFM-type treatment is equally effective for children with first-relapsed ALL treated according to the Japanese frontline protocols and for children with first-relapsed ALL treated according to the BFM-type frontline protocols.

Patient-Specific Circulating Tumor DNA for Monitoring Response to Menin Inhibitor Treatment in Preclinical Models of Infant Leukemia

BACKGROUND

In infant KMT2A (MLL1)-rearranged (MLL-r) acute lymphoblastic leukemia (ALL), early relapse and treatment response are currently monitored through invasive repeated bone marrow (BM) biopsies. Circulating tumor DNA (ctDNA) in peripheral blood (PB) provides a minimally invasive alternative, allowing for more frequent disease monitoring. However, a poor understanding of ctDNA dynamics has hampered its clinical translation. We explored the predictive value of ctDNA for detecting minimal/measurable residual disease (MRD) and drug response in a patient-derived xenograft (PDX) model of infant MLL-r ALL.

METHODS

Immune-deficient mice engrafted with three MLL-r ALL PDXs were monitored for ctDNA levels before and after treatment with the menin inhibitor SNDX-50469.

RESULTS

The amount of ctDNA detected strongly correlated with leukemia burden during initial engraftment prior to drug treatment. However, following SNDX-50469 treatment, the leukemic burden assessed by either PB leukemia cells through flow cytometry or ctDNA levels through droplet digital polymerase chain reaction (ddPCR) was discrepant. This divergence could be attributed to the persistence of leukemia cells in the spleen and BM, highlighting the ability of ctDNA to reflect disease dynamics in key leukemia infiltration sites.

CONCLUSIONS

Notably, ctDNA analysis proved to be a superior predictor of MRD compared to PB assessment alone, especially in instances of low disease burden. These findings highlight the potential of ctDNA as a sensitive biomarker for monitoring treatment response and detecting MRD in infant MLL-r ALL.

Prenatal origin of NUTM1 gene rearrangement in infant B-cell precursor acute lymphoblastic leukaemia

Rearrangement of NUTM1 gene (NUTM1r) is one of the most frequent aberrations occurring in infants (younger than 1 year at diagnosis) with B-cell precursor Acute Lymphoblastic Leukaemia (BCP-ALL). In this study we had the unique opportunity to analyze the umbilical cord blood (UCB) sample from one infant patient with NUTM1r BCP-ALL. Herein we reported for the first time that NUTM1r infant ALL arise prenatally, as both the patient-specific CUX1::NUTM1 fusion gene, as well as two IG/TR leukaemic markers were already present and detectable in the patient's UCB at birth. Our results clearly demonstrate the prenatal origin of NUTM1r infant BCP-ALL.

Results of the prospective EORTC Children Leukemia Group study 58081 in precursor B- and T-cell acute lymphoblastic leukemia

Here, we report the results of the prospective cohort study EORTC-CLG 58081 and compare them to the control arm of the randomized phase 3 trial EORTC-CLG 58951, on which treatment recommendations were built. In both studies, patients aged 1-18 years with BCR::ABL1 negative acute lymphoblastic leukemia of the B-lineage (B-ALL) or T-lineage (T-ALL) were treated using a BFM backbone without cranial irradiation. Similarly to the control arm of 58951, prednisolone (PRED) 60 mg/m2/day was used for induction therapy, but a few modifications were made. Dexamethasone (DXM) was used in average-risk 2 (AR2) T-ALL and B-ALL during induction, 10 and 6 mg/m2/day, respectively. Leucovorin rescue was delayed to 42 h instead of 36 h after initiation of high-dose methotrexate, and a postconsolidation MRD time point was added to stratify patients. Between 2011 and 2017, 835 patients were prospectively enrolled in the 58081 study. Overall, the 5-year event-free survival (EFS) was 84.8% versus 83.6% (hazard ratio [HR], 0.96 [95% confidence interval [CI]: 0.76-1.21]) for 58081 versus 58951 considered as a control group, respectively, 84.3% versus 84.9% (HR, 1.06 [99% CI: 0.75-1.49]) in B-ALL but 87.3% versus 76.6% (HR, 0.59 [99% CI: 0.28-1.24]) in T-ALL. The comparison between the two studies regarding EFS differed by risk group (p = 0.012). The HR was 2.15 (99% CI: 0.67-6.85) for very low-risk but 0.34 (99% CI: 0.13-0.89) for AR2. The particularly favorable results observed in the T-ALLs and AR2 subgroups suggest the benefit of using DXM in specific patient groups and highlight the importance of risk stratification.

Older Adults with Ph Negative Acute Lymphoblastic Leukemia: A Monocentric Experience on 57 Patients Focusing on Treatment Intensity and Age-Related Prognosis

Background: Treating with curative intent elderly patients affected by acute lymphoblastic leukemia (ALL) is an unmet clinical need. Comorbidities, lower tolerance to organ toxicities, and poor disease-related prognostic features make it difficult to cure these patients. Objectives: To analyze the outcome of ALL elderly patients aged over 55 years treated intensively or with the best supportive care (BSC) over the last 20 years.  

Tailored Digital PCR Follow-Up of Rare Fusion Transcripts after Initial Detection through RNA Sequencing in Hematological Malignancies

Minimal residual disease (MRD) monitoring plays a pivotal role in the management of hematologic malignancies. Well-established molecular targets, such as PML::RARA, CBFB::MYH11, or RUNX1::RUNX1T1, are conventionally tracked by quantitative RT-PCR. Recently, a broader landscape of fusion transcripts has been unveiled through transcriptomic analysis. These newly discovered fusion transcripts may emerge as novel molecular markers for MRD quantification. In this study, we compared a targeted RNA-sequencing (RNA-seq) approach (FusionPlex) with a whole-transcriptomic strategy (Advanta RNA-Seq XT) for fusion detection in a training set of 21 samples. We evidenced a concordance of 100% for the detection of known fusions, and showed a good correlation for gene expression quantification between the two techniques (Spearman r = 0.77). Additionally, we prospectively evaluated the identification of fusions by targeted RNA-seq in a real-life series of 126 patients with hematological malignancy. At least one fusion transcript was detected for 60 patients (48%). We designed tailored digital PCR assays for 11 rare fusions, and validated this technique for MRD quantification with a limit of detection of <0.01%. The combination of RNA-seq and tailored digital PCR may become a new standard for MRD evaluation in patients lacking conventional molecular targets.

Are measurable residual disease results after consolidation therapy useful in children with acute lymphoblastic leukemia?

Measurable residual disease (MRD) is regularly tested at later timepoints after the end of first consolidation (EOC) in children with acute lymphoblastic leukemia (ALL). The question remains whether this is useful for detecting (molecular) relapse. We investigated the clinical relevance of MRD after EOC in intermediate risk patients treated on DCOG-ALL-10 (n = 271) and DCOG-ALL-9 (n = 122), with MRD <0.05% at EOC. EOC MRD-negative patients (n = 178) had excellent outcomes, irrespective of MRD results at later timepoints; 6-year cumulative incidence of relapse (6-y CIR) of 7.4% (95% CI, 3.9%-12.3%) for those with MRD negativity at all later timepoints compared to 3.8% (95% CI, 0.3%-16.8%) for those with one or more later timepoints being positive (p = 0.51). Patients with positive EOC MRD (n = 91) of whom the subsequent timepoints were MRD negative (n = 43), had comparable good outcomes, 6-y CIR of 7.0% (95% CI, 1.8%-17.2%). In contrast, patients being MRD positive at EOC and MRD positive at one or more subsequent timepoints (n = 48) had a higher risk of relapse, 6-y CIR 29.4% (95% CI, 17.2%-42.8%), p < 0.001. These findings were confirmed in the validation cohort of ALL-9 as well as using the updated EuroMRD guidelines. In EOC MRD-negative patients, subsequent MRD measurements can be abandoned. For EOC MRD-positive patients the subsequent MRD measurement might be informative for further risk stratification.

Measurable residual disease (MRD)-testing in haematological cancers: A giant leap forward or sideways?

Measurable residual disease (MRD)-testing is used in many haematological cancers to estimate relapse risk and to direct therapy. Sometimes MRD-test results are used for regulatory approval. However, some people including regulators wrongfully believe results of MRD-testing are highly accurate and of proven efficacy in directing therapy. We review MRD-testing technologies and evaluate the accuracy of MRD-testing for predicting relapse and the strength of evidence supporting efficacy of MRD-guided therapy. We show that at the individual level MRD-test results are often an inaccurate relapse predictor. Also, no convincing data indicate that increasing therapy-intensity based on a positive MRD-test reduces relapse risk or improves survival. We caution against adjusting therapy-intensity based solely on results of MRD-testing.

Indeterminate measurable residual disease by multiparameter flow cytometry is associated with an intermediate risk of clinical relapse in adult patients with acute leukaemia

Measurable residual disease (MRD) is useful for prognostication and for monitoring response to treatment in patients with acute leukaemia. MRD by multiparametric flow cytometry (MFC-MRD) utilises the leukaemia-associated immunophenotype (LAIP) and difference from normal (DfN) strategies to identify the leukaemic clone. Difficulties arise when the LAIP overlaps with normal regeneration, there is clonal evolution, or when the abnormal clone population is exceptionally small e.g., <0.01% of CD45+ cells. Such cases are reported as 'indeterminate'; however, there is little international consensus on this reporting. The relationship between clinical outcomes and indeterminate MFC-MRD is unknown. Here we determine the rate of indeterminate MFC-MRD reporting, its relationship to concurrent molecular MRD results when available, and to clinical outcomes to 12 months. We performed an internal audit of all adult testing for MFC-MRD between January and December 2021. A total of 153 consecutive patients with a diagnosis of acute leukaemia were included. Successive MFC-MRD results and clinical outcomes were recorded over a 12-month period from time of inclusion into the study. In total, 460 MFC-MRD tests from 153 patients were reviewed and 73 (16%) MFC-MRD tests from 54 (35%) patients were reported as indeterminate. The majority (70%) were at low levels between 0.01-0.1% of CD45+ cells. Compared to patients with a negative result, acute myeloid leukaemia (AML) was more frequent in patients who had an indeterminate MFC-MRD (70% vs 36%), and B-cell acute lymphoblastic leukaemia was less common (20% vs 55%). In patients with indeterminate MFC-MRD results, one-third had received either chemotherapy or allogeneic haemopoietic stem cell transplant (aHSCT) within the preceding 3 months. Agreement between MFC and molecular MRD testing was low. Patients with indeterminate MFC-MRD had leukaemia relapse rates below patients with a positive MFC-MRD, but greater than those with negative MFC-MRD (positive 33% vs indeterminate 21% vs negative 8%, p = 0.038). Overall, these findings indicate that indeterminate MFC-MRD results are more common in adults with AML and also in those who have received chemotherapy or aHSCT within the previous 3 months. We report for the first time that indeterminate MFC-MRD is a finding of potential clinical significance, which associates with a numerically higher median relapse rate within 12 months when compared to a negative MFC-MRD result.

Significance of Measurable Residual Disease in Adult Philadelphia Chromosome-Positive ALL: A GRAAPH-2014 Study

PURPOSE

BCR::ABL1 quantification is widely regarded as the standard for monitoring measurable residual disease (MRD) in Philadelphia chromosome-positive (Ph+) ALL. However, recent evidence of BCR::ABL1 multilineage involvement questions the significance of BCR::ABL1 MRD. We aimed to define the prognostic role of MRD as assessed by BCR::ABL1 or lymphoid-specific immunoglobulin/T-cell receptor (IG/TR) gene markers.

PATIENTS AND METHODS

We conducted BCR::ABL1 and IG/TR quantification after each treatment cycle in 264 patients treated in the GRAAPH-2014 trial, which used four cycles of reduced-intensity chemotherapy with nilotinib, followed by hematopoietic stem-cell transplantation (HSCT).

RESULTS

Comparing BCR::ABL1 and IG/TR MRD revealed residual BCR::ABL1-positive non-ALL cells in 98 (43%) of 228 patients, defining multilineage Ph+ ALL. Despite poorer BCR::ABL1 responses, patients with multilineage Ph+ ALL had similar disease-free survival (DFS; hazard ratio [HR], 0.83 [95% CI, 0.49 to 1.41]; P = .50). Although BCR::ABL1 response failed to predict outcomes, IG/TR positivity (≥0.01%) was strongly associated with lower DFS (after cycle 2, HR, 2.49 [95% CI, 1.40 to 4.40]; P = .002; after cycle 4, HR, 4.13 [95% CI, 1.82 to 9.38]; P = .001). In multivariable analysis, both IG/TR positivity after cycle 2 and initial WBC count ≥30 × 109/L predicted poorer DFS, enabling to define a high-risk group having a 4-year DFS of 56.5% compared with 87.6% (HR, 3.72 [95% CI, 1.93 to 7.15]; P < .001). Moreover, allogeneic HSCT significantly improved DFS in the high-risk group (HR, 0.33 [95% CI, 0.18 to 0.60]; P < .001), whereas the standard-risk group had favorable outcomes regardless of allogeneic HSCT.

CONCLUSION

Our findings challenge the significance of BCR::ABL1 monitoring in adult Ph+ ALL and demonstrate the prognostic role of IG/TR MRD. This study provides a framework for using MRD to guide treatment strategies in adults with Ph+ ALL.

Relationship between subtype-specific minimal residual disease level and long-term prognosis in children with acute lymphoblastic leukemia

Minimal residual disease (MRD) based risk stratification criteria for specific genetic subtypes remained unclear in childhood acute lymphoblastic leukemia (ALL). Among 723 children with newly diagnosed ALL treated with the Chinese Children Leukemia Group CCLG-2008 protocol, MRD was assessed at time point 1 (TP1, at the end of induction) and TP2 (before consolidation treatment) and the MRD levels significantly differed in patients with different fusion genes or immunophenotypes (P all < 0.001). Moreover, the prognostic impact of MRD varied by distinct molecular subtypes. We stratified patients in each molecular subtype into two MRD groups based on the results. For patients carrying BCR::ABL1 or KMT2A rearrangements, we classified patients with MRD < 10-2 at both TP1 and TP2 as the low MRD group and the others as the high MRD group. ETV6::RUNX1+ patients with TP1 MRD < 10-3 and TP2 MRD-negative were classified as the low MRD group and the others as the high MRD group. For T-ALL, We defined children with TP1 MRD ≥ 10-3 as the high MRD group and the others as the low MRD group. The 10-year relapse-free survival of low MRD group was significantly better than that of high MRD group. We verified the prognostic impact of the subtype-specific MRD-based stratification in patients treated with the BCH-ALL2003 protocol. In conclusion, the subtype-specific MRD risk stratification may contribute to the precise treatment of childhood ALL.

MRD in Philadelphia Chromosome-Positive ALL: Methodologies and Clinical Implications

PURPOSE OF REVIEW

Measurable residual disease (MRD) is integral in the management of Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). This review discusses the current methods used to evaluate MRD as well as the interpretation, significance, and incorporation of MRD in current practice.

RECENT FINDINGS

New molecular technologies have allowed the detection of MRD to levels as low as 10- 6. The most used techniques to evaluate MRD are multiparametric flow cytometry (MFC), quantitative reverse transcription polymerase chain reaction (RT-qPCR), and high-throughput next-generation sequencing (NGS). Each method varies in terms of advantages, disadvantages, and MRD sensitivity. MRD negativity after induction treatment and after allogeneic hematopoietic cell transplantation (HCT) is an important prognostic marker that has consistently been shown to be associated with improved outcomes. Blinatumomab, a new targeted therapy for Ph + ALL, demonstrates high efficacy in eradicating MRD and improving patient outcomes. In the relapsed/refractory setting, the use of inotuzumab ozogamicin and tisagenlecleucel has shown promise in eradicating MRD. The presence of MRD has become an important predictive measure in Ph + ALL. Current studies evaluate the use of MRD in treatment decisions, especially in expanding therapeutic options for Ph + ALL, including tyrosine kinase inhibitors, targeted antibody therapies, chimeric antigen receptor cell therapy, and HCT.

PlentiPlex™ MYD88 Waldenström lymphoma qPCR assay: A highly sensitive method for detection of MYD88 L265P mutation

INTRODUCTION

Agarose gel-based conventional and real-time allele-specific polymerase chain reaction (AS-PCR) assays are currently used for sensitive detection and quantification of MYD88 L265P mutation. Visual inspection of an agarose gel can often be ambiguous. We propose a new allele-specific quantification PCR (AS-qPCR) assay, PlentiPlex™ MYD88 Waldenström lymphoma qPCR assay, that uses Intercalating Nucleic Acid (INA®) technology for increased affinity and specificity.

METHODS

This study compares PlentiPlex™ MYD88 Waldenström lymphoma qPCR assay with conventional AS-PCR. We included a total of 102 peripheral and bone marrow blood samples from 94 patients with a lymphoproliferative disorder. Droplet digital PCR (ddPCR) was used as a third method in case of discrepancy.

RESULTS

A positive percent agreement of 100% (95% CI 0.92-1.0) and a negative percent agreement of 98% (95% CI 0.90-1.0) were found between the conventional AS-PCR and the AS-qPCR methods. Including the ddPCR results to validate the discrepant cases, the sensitivity and specificity of PlentiPlex™ MYD88 Waldenström lymphoma qPCR Assay were 1.0 (95% CI 0.97-1.0) and 1.0 (95% CI 0.96-1.0), respectively.

CONCLUSION

Our data demonstrate that PlentiPlex™ MYD88 Waldenström lymphoma qPCR assay is a fast, highly sensitive, and specific method for the detection of MYD88 L265P compared with conventional AS-PCR.

Evaluation of next-generation sequencing for measurable residual disease monitoring in three major fusion transcript subtypes of B-precursor acute lymphoblastic leukaemia

The use of next-generation sequencing (NGS) for monitoring measurable residual disease (MRD) in acute lymphoblastic leukaemia (ALL) has been gaining traction. This study aimed to investigate the utility of NGS in MRD monitoring for the three major fusion transcript (FT) subtypes of B-precursor ALL (B-ALL). The MRD results for 104 bone marrow samples from 56 patients were analysed through NGS and real time quantitative reverse transcription PCR (RT-qPCR) for the three major FTs: BCR::ABL1, TCF3::PBX1, and ETV6::RUNX1. To validate the NGS approach, NGS-MRD was initially compared with allele-specific oligonucleotide-qPCR-MRD, and the coefficient of determination was good (R2=0.8158). A subsequent comparison of NGS-MRD with FT-MRD yielded a good coefficient of determination (R2=0.7690), but the coefficient varied by subtype. Specifically, the R2 was excellent for TCF3::PBX1 ALL (R2=0.9157), good for ETV6::RUNX1 ALL (R2=0.8606), and subpar for BCR::ABL1 ALL (R2=0.5763). The overall concordance between the two methods was 83.7%, and an excellent concordance rate of 95.8% was achieved for TCF3::PBX1 ALL. Major discordance, which was defined as a >1 log difference between discordant NGS-MRD and FT-MRD, occurred in 6.7% of the samples, with all but one sample being BCR::ABL1 ALL. Among the four non-transplanted patients with BCR::ABL1-MRD (+)/NGS-MRD (-), three did not relapse after long-term follow-up. Our finding indicates that NGS-MRD has a better prognostic impact than RT-qPCR-MRD in ETV6::RUNX1 and BCR::ABL1 ALL, whereas in TCF3::PBX1 ALL, both methods exhibit comparable efficacy.

Stem cell collection and hematological recovery in the Fondazione Italiana Linfomi (FIL) MCL0208 clinical trial

In the frontline high-dose phase 3 FIL-MCL0208 trial (NCT02354313), 8% of enrolled mantle cell lymphoma (MCL) patients could not be randomised to receive lenalidomide (LEN) maintenance vs observation after autologous stem cell transplantation (ASCT) due to inadequate hematological recovery and 52% of those who started LEN, needed a dose reduction due to toxicity. We therefore focused on the role played by CD34 + hematopoietic stem cells (PBSC) harvesting and reinfusion on toxicity and outcome. Overall, 90% (n = 245) of enrolled patients who underwent the first leukapheresis collected ≥ 4 × 106 PBSC/kg, 2.6% (n = 7) mobilized < 4 × 106 PBSC/kg and 7.7% (n = 21) failed the collection. Similar results were obtained for the planned second leukapheresis, with only one patient failing both attempts. Median count of reinfused PBSC was 5 × 106/kg and median time to recovery from neutropenia G4 was 10 days from ASCT. No impact of mobilizing subtype or number of reinfused PBSC on hematological recovery and LEN dose reduction was noted. At a median follow-up of 75 months from ASCT, PFS and OS of transplanted patients were 50% and 73%, respectively. A long lasting G4 neutropenia after ASCT (> 10 days) was associated with a worse outcome, both in terms of PFS and OS. In conclusion, although the harvesting procedures proved feasible for younger MCL patients, long-lasting cytopenia following ASCT remains a significant issue: this can hinder the administration of effective maintenance therapies, potentially increasing the relapse rate and negatively affecting survival outcomes.

Realizing precision medicine in chronic lymphocytic leukemia: Remaining challenges and potential opportunities

Patients with chronic lymphocytic leukemia (CLL) exhibit diverse clinical outcomes. An expanding array of genetic tests is now employed to facilitate the identification of patients with high-risk disease and inform treatment decisions. These tests encompass molecular cytogenetic analysis, focusing on recurrent chromosomal alterations, particularly del(17p). Additionally, sequencing is utilized to identify TP53 mutations and to determine the somatic hypermutation status of the immunoglobulin heavy variable gene. Concurrently, a swift advancement of targeted treatment has led to the implementation of novel strategies for patients with CLL, including kinase and BCL2 inhibitors. This review explores both current and emerging diagnostic tests aimed at identifying high-risk patients who should benefit from targeted therapies. We outline existing treatment paradigms, emphasizing the importance of matching the right treatment to the right patient beyond genetic stratification, considering the crucial balance between safety and efficacy. We also take into consideration the practical and logistical issues when choosing a management strategy for each individual patient. Furthermore, we delve into the mechanisms underlying therapy resistance and stress the relevance of monitoring measurable residual disease to guide treatment decisions. Finally, we underscore the necessity of aggregating real-world data, adopting a global perspective, and ensuring patient engagement. Taken together, we argue that precision medicine is not the mere application of precision diagnostics and accessibility of precision therapies in CLL but encompasses various aspects of the patient journey (e.g., lifestyle exposures and comorbidities) and their preferences toward achieving true personalized medicine for patients with CLL.

Local radiotherapy and measurable residual disease-driven immunotherapy in patients with early-stage follicular lymphoma (FIL MIRO): final results of a prospective, multicentre, phase 2 trial

BACKGROUND

The mainstay of treatment for early-stage follicular lymphoma is local radiotherapy, with a possible role for anti-CD20 monoclonal antibody (mAb). We aimed to evaluate the effect of these treatments using a measurable residual disease (MRD)-driven approach.

METHODS

This prospective, multicentre, phase 2 trial was conducted at 27 centres of the Fondazione Italiana Linfomi (FIL) in Italy. Eligible participants were adults (≥18 years) with newly diagnosed, histologically confirmed follicular lymphoma (stage I or II; grade I-IIIa). Patients were initially treated with 24 Gy involved-field radiotherapy over 12 days; those who were MRD-positive after radiotherapy or during follow-up received eight intravenous doses (1000 mg per dose; one dose per week) of the anti-CD20 mAb ofatumumab. The primary endpoint was the proportion of patients who were MRD-positive after involved-field radiotherapy and became MRD-negative after ofatumumab treatment. Patients were included in the primary endpoint analysis population if they were positive for BCL2::IGH rearrangement at enrolment in peripheral blood or bone marrow samples. MRD positivity was defined as the persistence of BCL2::IGH rearrangement in peripheral blood or bone marrow, assessed centrally by laboratories of the FIL MRD Network. The trial was registered with EudraCT, 2012-001676-11.

FINDINGS

Between May 2, 2015, and June 1, 2018, we enrolled 110 participants, of whom 106 (96%) were eligible and received involved-field radiotherapy. Of these, 105 (99%) were White, one (1%) was Black, 50 (47%) were male, and 56 (53%) were female. Of 105 participants in whom BCL2::IGH status was evaluable, 32 (30%) had a detectable BCL2::IGH rearrangement at baseline. After radiotherapy, 12 (40%) of 30 patients reached MRD-negative status, which was long-lasting (at least 36 or 42 months) in three (25%). In those who were MRD-positive after radiotherapy, ofatumumab induced MRD-negativity in 23 (92%; 95% CI 74-99) of 25 evaluable patients. After a median follow-up of 46·1 months (IQR 42·8-50·8), 14 (61%) of these 23 patients remain in complete response and are MRD-negative. The most common grade 3-4 adverse events were infusion-related reactions, observed in four patients.

INTERPRETATION

Local radiotherapy is frequently not associated with the eradication of follicular lymphoma. An MRD-driven, anti-CD20 monoclonal antibody consolidation enables molecular remission to be reached in almost all patients and is associated with a reduced incidence of relapse over time. A clinical advantage of an MRD-driven consolidation is therefore suggested.

FUNDING

AIRC Foundation for Cancer Research in Italy, Novartis International, and GlaxoSmithKline.

Analysis of measurable residual disease by IG/TR gene rearrangements: quality assurance and updated EuroMRD guidelines

Minimal/measurable residual disease (MRD) diagnostics using real-time quantitative PCR analysis of rearranged immunoglobulin and T-cell receptor gene rearrangements are nowadays implemented in most treatment protocols for patients with acute lymphoblastic leukemia (ALL). Within the EuroMRD Consortium, we aim to provide comparable, high-quality MRD diagnostics, allowing appropriate risk-group classification for patients and inter-protocol comparisons. To this end, we set up a quality assessment scheme, that was gradually optimized and updated over the last 20 years, and that now includes participants from around 70 laboratories worldwide. We here describe the design and analysis of our quality assessment scheme. In addition, we here report revised data interpretation guidelines, based on our newly generated data and extensive discussions between experts. The main novelty is the partial re-definition of the "positive below quantitative range" category by two new categories, "MRD low positive, below quantitative range" and "MRD of uncertain significance". The quality assessment program and revised guidelines will ensure reproducible and accurate MRD data for ALL patients. Within the Consortium, similar programs and guidelines have been introduced for other lymphoid diseases (e.g., B-cell lymphoma), for new technological platforms (e.g., digital droplet PCR or Next-Generation Sequencing), and for other patient-specific MRD PCR-based targets (e.g., fusion genes).

Monitoring Response and Resistance to Treatment in Chronic Lymphocytic Leukemia

The recent evolution in chronic lymphocytic leukemia (CLL) targeted therapies led to a progressive change in the way clinicians manage the goals of treatment and evaluate the response to treatment in respect to the paradigm of the chemoimmunotherapy era. Continuous therapies with BTK inhibitors achieve prolonged and sustained control of the disease. On the other hand, venetoclax and anti-CD20 monoclonal antibodies or, more recently, ibrutinib plus venetoclax combinations, given for a fixed duration, achieve undetectable measurable residual disease (uMRD) in the vast majority of patients. On these grounds, a time-limited MRD-driven strategy, a previously unexplored scenario in CLL, is being attempted. On the other side of the spectrum, novel genetic and non-genetic mechanisms of resistance to targeted treatments are emerging. Here we review the response assessment criteria, the evolution and clinical application of MRD analysis and the mechanisms of resistance according to the novel treatment strategies within clinical trials. The extent to which this novel evidence will translate in the real-life management of CLL patients remains an open issue to be addressed.

Faster clinical decisions in B-cell acute lymphoblastic leukaemia: A single flow cytometric 12-colour tube improves diagnosis and minimal residual disease follow-up

Assessing minimal residual disease (MRD) in B-cell precursor acute lymphoblastic leukaemia (BCP-ALL) is essential for adjusting therapeutic strategies and predicting relapse. Quantitative polymerase chain reaction (qPCR) is the gold standard for MRD. Alternatively, flow cytometry is a quicker and cost-effective method that typically uses leukaemia-associated immunophenotype (LAIP) or different-from-normal (DFN) approaches for MRD assessment. This study describes an optimized 12-colour flow cytometry antibody panel designed for BCP-ALL diagnosis and MRD monitoring in a single tube. This method robustly differentiated hematogones and BCP-ALL cells using two specific markers: CD43 and CD81. These and other markers (e.g. CD73, CD66c and CD49f) enhanced the specificity of BCP-ALL cell detection. This innovative approach, based on a dual DFN/LAIP strategy with a principal component analysis method, can be used for all patients and enables MRD analysis even in the absence of a diagnostic sample. The robustness of our method for MRD monitoring was confirmed by the strong correlation (r = 0.87) with the qPCR results. Moreover, it simplifies and accelerates the preanalytical process through the use of a stain/lysis/wash method within a single tube (<2 h). Our flow cytometry-based methodology improves the BCP-ALL diagnosis efficiency and MRD management, offering a complementary method with considerable benefits for clinical laboratories.

TBI, etoposide, and cyclophosphamide conditioning for intermediate-risk relapsed childhood acute lymphoblastic leukemia

BACKGROUND

In children with intermediate-risk relapsed acute lymphoblastic leukemia (ALL), allogeneic hematopoietic stem cell transplantation (allo-HSCT) has markedly improved the outcome of patients with an unsatisfactory minimal residual disease (MRD) response. Total body irradiation (TBI), etoposide (ETP), and cyclophosphamide (CY) have been shown to be equivalent to or better than TBI + ETP for conditioning, so we hypothesized that even greater survival could be achieved due to recent advances in HSCT and supportive care.

PROCEDURE

We prospectively analyzed the efficacy and safety of allo-HSCT with a unified conditioning regimen of TBI + ETP + CY in children with intermediate-risk relapsed ALL, based on MRD in the bone marrow after induction, from the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG) ALL-R08-II nationwide cohort (UMIN000002025).

RESULTS

Twenty patients with post-induction MRD ≥ 10-3 and two not evaluated for MRD underwent allo-HSCT. Engraftment was confirmed in all patients, and no transplantation-related mortality was observed. The 3-year event-free survival and overall survival rates after transplantation were 86.4% ± 7.3% and 95.5% ± 4.4%, respectively.

CONCLUSION

Allo-HSCT based on post-induction MRD with TBI + ETP + CY conditioning was feasible in Japanese children with intermediate-risk relapsed ALL.

Refining risk stratification in paediatric B-acute lymphoblastic leukaemia: Combining IKZF1plus and Day 15 MRD positivity

This study investigates the potential utility of IKZF1 deletion as an additional high-risk marker for paediatric acute lymphoblastic leukaemia (ALL). The prognostic impact of IKZF1 status, in conjunction with minimal/measurable residual disease (MRD), was evaluated within the MRD-guided TPOG-ALL-2013 protocol using 412 newly diagnosed B-ALL patients aged 1-18. IKZF1 status was determined using multiplex ligation-dependent probe amplification. IKZF1 deletions, when co-occurring with CDKN2A, CDKN2B, PAX5 or PAR1 region deletions in the absence of ERG deletions, were termed IKZF1plus. Both IKZF1 deletion (14.6%) and IKZF1plus (7.8%) independently predicted poorer outcomes in B-ALL. IKZF1plus was observed in 4.1% of Philadelphia-negative ALL, with a significantly lower 5-year event-free survival (53.9%) compared to IKZF1 deletion alone (83.8%) and wild-type IKZF1 (91.3%) (p < 0.0001). Among patients with Day 15 MRD ≥0.01%, provisional high-risk patients with IKZF1plus exhibited the worst outcomes in event-free survival (42.0%), relapse-free survival (48.0%) and overall survival (72.7%) compared to other groups (p < 0.0001). Integration of IKZF1plus and positive Day 15 MRD identified a subgroup of Philadelphia-negative B-ALL with a 50% risk of relapse. This study highlights the importance of assessing IKZF1plus alongside Day 15 MRD positivity to identify patients at increased risk of adverse outcomes, potentially minimizing overtreatment.

Genomic breakpoint-specific monitoring of measurable residual disease in pediatric non-standard-risk acute myeloid leukemia

Pediatric acute myeloid leukemia (AML) is a highly heterogeneous disease making standardized measurable residual disease (MRD) assessment challenging. Currently, patient-specific DNA-based assays are only rarely applied for MRD assessment in pediatric AML. We tested whether quantification of genomic breakpoint-specific sequences via quantitative polymerase chain reaction (gDNA-PCR) provides a reliable means of MRD quantification in children with non-standardrisk AML and compared its results to those obtained with state-of-the-art ten-color flow cytometry (FCM). Breakpointspecific gDNA-PCR assays were established according to Euro-MRD consortium guidelines. FCM-MRD assessment was performed according to the European Leukemia Network guidelines with adaptations for pediatric AML. Of 77 consecutively recruited non-standard-risk pediatric AML cases, 49 (64%) carried a chromosomal translocation potentially suitable for MRD quantification. Genomic breakpoint analysis returned a specific DNA sequence in 100% (41/41) of the cases submitted for investigation. MRD levels were evaluated using gDNA-PCR in 243 follow-up samples from 36 patients, achieving a quantitative range of at least 10-4 in 231/243 (95%) of samples. Comparing gDNA-PCR with FCM-MRD data for 183 bone marrow follow-up samples at various therapy timepoints showed a high concordance of 90.2%, considering a cut-off of ≥0.1%. Both methodologies outperformed morphological assessment. We conclude that MRD monitoring by gDNA-PCR is feasible in pediatric AML with traceable genetic rearrangements and correlates well with FCM-MRD in the currently applied clinically relevant range, while being more sensitive below that. The methodology should be evaluated in larger cohorts to pave the way for clinical application.

Predictive Value of Minimal Residual Disease for Efficacy of Rituximab Maintenance in Mantle Cell Lymphoma: Results From the European Mantle Cell Lymphoma Elderly Trial

PURPOSE

The outcome of older patients with mantle cell lymphoma (MCL) has improved by the introduction of immunochemotherapy, followed by rituximab (R)-maintenance. Assessment of minimal residual disease (MRD) represents a promising tool for individualized treatment decisions and was a prospectively planned part of the European MCL Elderly trial. We investigated how MRD status influenced the efficacy of R-maintenance and how MRD can enable tailored consolidation strategies.

PATIENTS AND METHODS

Previously untreated patients with MCL age 60 years or older have been randomly assigned to R versus interferon-alpha maintenance after response to rituximab, fludarabine, cyclophosphamide (R-FC) versus rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone (R-CHOP). MRD monitoring was performed by real-time quantitative polymerase chain reaction (qPCR) following EuroMRD guidelines.

RESULTS

A qPCR assay with a median sensitivity of 1 × 10-5 could be generated in 80% of 288 patients in an international, multicenter, multilaboratory setting. More extensive tumor dissemination facilitated the identification of a molecular marker. The efficacy of R-maintenance in clinical remission was confirmed for MRD-negative patients at the end of induction in terms of progression-free survival (PFS; hazard ratio [HR], 0.38 [95% CI, 0.21 to 0.63]) and overall survival (OS; HR, 0.37 [95% CI, 0.20 to 0.68]), particularly in R-CHOP-treated patients (PFS-HR, 0.23 [95% CI, 0.10 to 0.52]; OS-HR, 0.19 [95% CI, 0.07 to 0.52]). R-maintenance appeared less effective in MRD-positive patients (PFS-HR, 0.51 [95% CI, 0.26 to 1.02]) overall and after R-CHOP induction (PFS-HR, 0.59 [95% CI, 0.28 to 1.26]). R-FC achieved more frequent and faster MRD clearance compared with R-CHOP. MRD positivity in clinical remission after induction was associated with a short median time to clinical progression of approximately 1-1.7 years.

CONCLUSION

The results confirm the strong efficacy of R-maintenance in patients who are MRD-negative after induction. Treatment de-escalation for MRD-negative patients is discouraged by our results. More effective consolidation strategies should be explored in MRD-positive patients to improve their long-term prognosis.

Minimal Residual Disease Status Predicts Outcome in Patients With Previously Untreated Follicular Lymphoma: A Prospective Analysis of the Phase III GALLIUM Study

PURPOSE

We report an analysis of minimal residual/detectable disease (MRD) as a predictor of outcome in previously untreated patients with follicular lymphoma (FL) from the randomized, multicenter GALLIUM (ClinicalTrials.gov identifier: NCT01332968) trial.

PATIENTS AND METHODS

Patients received induction with obinutuzumab (G) or rituximab (R) plus bendamustine, or cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) or cyclophosphamide, vincristine, prednisone (CVP) chemotherapy, followed by maintenance with the same antibody in responders. MRD status was assessed at predefined time points (mid-induction [MI], end of induction [EOI], and at 4-6 monthly intervals during maintenance and follow-up). Patients with evaluable biomarker data at diagnosis were included in the survival analysis.

RESULTS

MRD positivity was associated with inferior progression-free survival (PFS) at MI (hazard ratio [HR], 3.03 [95% CI, 2.07 to 4.45]; P < .0001) and EOI (HR, 2.25 [95% CI, 1.53 to 3.32]; P < .0001). MRD response was higher after G- versus R-chemotherapy at MI (94.2% v 88.9%; P = .013) and at EOI (93.1% v 86.7%; P = .0077). Late responders (MI-positive/EOI-negative) had a significantly poorer PFS than early responders (MI-negative/EOI-negative; HR, 3.11 [95% CI, 1.75 to 5.52]; P = .00011). The smallest proportion of MRD positivity was observed in patients receiving bendamustine at MI (4.8% v 16.0% in those receiving CHOP; P < .0001). G appeared to compensate for less effective chemotherapy regimens, with similar MRD response rates observed across the G-chemo groups. During the maintenance period, more patients treated with R than with G were MRD-positive (R-CHOP, 20.7% v G-CHOP, 7.0%; R-CVP, 21.7% v G-CVP, 9.4%). Throughout maintenance, MRD positivity was associated with clinical relapse.

CONCLUSION

MRD status can determine outcome after induction and during maintenance, and MRD negativity is a prerequisite for long-term disease control in FL. The higher MRD responses after G- versus R-based treatment confirm more effective tumor cell clearance.

MRD-driven treatment with venetoclax-R2 in mantle cell lymphoma: the Nordic Lymphoma Group MCL7 VALERIA trial

ABSTRACT

Despite improvements in treatment of mantle cell lymphoma (MCL), most patients eventually relapse. In this multicenter phase 1b/2 trial, we evaluated safety and efficacy of minimal residual disease (MRD)-driven venetoclax, lenalidomide, and rituximab (venetoclax-R2) in relapsed/refractory (R/R) MCL and explored the feasibility of stopping treatment in molecular remission. The primary end point was overall response rate (ORR) at 6 months. After dose escalation, the recommended phase 2 dose was lenalidomide 20 mg daily, days 1 to 21; venetoclax 600 mg daily after ramp-up; and rituximab 375 mg/m2 weekly for 4 weeks, then every 8 weeks. MRD monitoring by RQ-PCR was performed every 3 months. When MRD-negativity in the blood was reached, treatment was continued for another 3 months; if MRD-negativity was then confirmed, treatment was stopped. In total, 59 patients were enrolled, with a median age of 73 years. At 6 months, the ORR was 63% (29 complete remission [CR], 8 partial remission [PR]), and 40% (4 CR, 2 PR) for patients previously failing a Bruton tyrosine kinase (BTK) inhibitor. Median progression-free survival (PFS) was 21 months, with median overall survival of 31 months. TP53 mutation was associated with inferior PFS (P < .01). Overall, 28 patients (48%) discontinued treatment in molecular remission, and 25 remain MRD negative after a median of 17.4 months. Hematological toxicity was frequent, with 52 of 59 (88%) patients with G3-4 neutropenia and 21 of 59 (36%) patients with G3-4 thrombocytopenia. To conclude, MRD-driven venetoclax-R2 is feasible and tolerable and shows efficacy in R/R MCL, also after BTK inhibitor failure. This trial was registered at www.ClinicalTrials.gov as #NCT03505944.

Genomic DNA-based measurable residual disease monitoring in pediatric acute myeloid leukemia: unselected consecutive cohort study

Measurable residual disease (MRD) monitoring in childhood acute myeloid leukemia (AML) is used to assess response to treatment and for early detection of imminent relapse. In childhood AML, MRD is typically evaluated using flow cytometry, or by quantitative detection of leukemia-specific aberrations at the mRNA level. Both methods, however, have significant limitations. Recently, we demonstrated the feasibility of MRD monitoring in selected subgroups of AML at the genomic DNA (gDNA) level. To evaluate the potential of gDNA-based MRD monitoring across all AML subtypes, we conducted a comprehensive analysis involving 133 consecutively diagnosed children. Integrating next-generation sequencing into the diagnostic process, we identified (presumed) primary genetic aberrations suitable as MRD targets in 97% of patients. We developed patient-specific quantification assays and monitored MRD in 122 children. The gDNA-based MRD monitoring via quantification of primary aberrations with a sensitivity of at least 10-4 was possible in 86% of patients; via quantification with sensitivity of 5 × 10-4, of secondary aberrations, or at the mRNA level in an additional 8%. Importantly, gDNA-based MRD exhibited independent prognostic value at early time-points in patients stratified to intermediate-/high-risk treatment arms. Our study demonstrates the broad applicability, feasibility, and clinical significance of gDNA-based MRD monitoring in childhood AML.

Minimal Residual Disease in the Management of B-Cell Acute Lymphoblastic Leukemia: A Systematic Review of Studies from Indian Settings

Minimal residual disease (MRD) has become an essential tool in the management of B-cell acute lymphoblastic leukemia (B-ALL) and aids in tailoring treatment strategies to suit specific patient needs. Although much progress has been made in this area, there is limited data on the use of MRD in the Indian context. Our objective was to identify relevant literature that discusses the utility of MRD in the management of B-cell ALL in adolescents and young adults (AYA) and adults in Indian settings. A systematic search and screening of articles were performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The primary data source was PubMed followed by Google Scholar for articles and conference proceedings. Of the 254 records screened, 24 records were retained for analysis. MRD monitoring had a significant role in the management of AYA/adult B-cell ALL patients. Variability of results was observed across these studies with respect to methods, techniques, and use. However, these studies evidenced and validated the importance of MRD assessment in risk-adapted management of B-cell ALL and highlighted the need for optimization. The advances in MRD diagnostics and applications are yet to be tested and adopted in Indian settings. Hence, there is a need for in-depth research to develop and optimize approaches for calibrating country-specific management strategies. The potential role of MRD assessments in anticipating relapse or treatment failures warrants more attention for the preemptive positioning of novel strategies involving immunotherapies.

Genetic alterations and MRD refine risk assessment for KMT2A-rearranged B-cell precursor ALL in adults: a GRAALL study

KMT2A-rearranged (KMT2A-r) B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is widely recognized as a high-risk leukemia in both children and adults. However, there is a paucity of data on adults treated in recent protocols, and the optimal treatment strategy for these patients is still a matter of debate. In this study, we set out to refine the prognosis of adult KMT2A-r BCP-ALL treated with modern chemotherapy regimen and investigate the prognostic impact of comutations and minimal residual disease (MRD). Of 1091 adult patients with Philadelphia-negative BCP-ALL enrolled in 3 consecutive trials from the Group for Research on Adult Acute Lymphoblastic Leukemia (GRAALL), 141 (12.9%) had KMT2A-r, with 5-year cumulative incidence of relapse (CIR) and overall survival (OS) rates of 40.7% and 53.3%, respectively. Molecular profiling highlighted a low mutational burden in this subtype, reminiscent of infant BCP-ALL. However, the presence of TP53 and/or IKZF1 alterations defined a subset of patients with significantly poorer CIR (69.3% vs 36.2%; P = .001) and OS (28.1% vs 60.7%; P = .006) rates. Next, we analyzed the prognostic implication of MRD measured after induction and first consolidation, using both immunoglobulin (IG) or T-cell receptor (TR) gene rearrangements and KMT2A genomic fusion as markers. In approximately one-third of patients, IG/TR rearrangements were absent or displayed clonal evolution during the disease course, compromising MRD monitoring. In contrast, KMT2A-based MRD was highly reliable and strongly associated with outcome, with early good responders having an excellent outcome (3-year CIR, 7.1%; OS, 92.9%). Altogether, our study reveals striking heterogeneity in outcomes within adults with KMT2A-r BCP-ALL and provides new biomarkers to guide risk-based therapeutic stratification.

Measurable Residual Disease (MRD) by Flow Cytometry in Adult B-Acute Lymphoblastic Leukaemia (B-ALL) and Acute Myeloid Leukaemia (AML): Correlation with Molecular MRD Testing and Clinical Outcome at One Year

Measurable residual disease (MRD) detected by flow cytometry (FC) is well established in paediatric B- lymphoblastic leukaemia (B-ALL) and adult chronic lymphocytic leukaemia (CLL), but its utility in adult B-ALL and adult acute myeloid leukaemia (AML) is less clear. In this prospective MRD study, one of the largest in Australia to date, we examined consecutive bone marrow aspirates from adult participants with B-ALL (n = 47) and AML (n = 87) sent for FC-MRD testing at a quaternary referral hospital in Sydney. FC-MRD results were correlated to corresponding Mol-MRD testing where available and clinical outcomes at three-month intervals over 1 year. B-ALL showed a moderate positive correlation (rs = 0.401, p < 0.001), while there was no correlation between FC-MRD and Mol-MRD for AML (rs = 0.13, p = 0.237). Five FC-MRD patterns were identified which had significant associations with relapse (X2(4) = 31.17(4), p > 0.001) and survival (X2(4) = 13.67, p = 0.008) in AML, but not in B-ALL. The three-month MRD results were also strongly associated with survival in AML, while the association in B-ALL was less evident. There was a moderate correlation between FC-MRD and Mol-MRD in B-ALL but not AML. The association of FC-MRD with relapse and survival was stronger in AML than in B-ALL. Overall, these findings suggest divergent utilities of FC-MRD in AML and B-ALL.

Association of Minimal Residual Disease by a Single-Tube 8-Color Flow Cytometric Analysis With Clinical Outcome in Adult B-Cell Acute Lymphoblastic Leukemia: A Real-World Study Based on 486 Patients

CONTEXT.—

Minimal/measurable residual disease (MRD) measured by molecular and multiparametric flow cytometry (MFC) has been proven to be predictive of relapse and survival in patients with B-cell acute lymphoblastic leukemia (B-ALL). A universally applicable antibody panel at a low cost but without compromising sensitivity and power of prognosis prediction in adult B-ALL remains unestablished.

OBJECTIVE.—

To report our experience of using a single-tube 8-color MFC panel to measure the MRD status as a prognostic indicator in adult B-ALL patients.

DESIGN.—

We retrospectively analyzed the characteristics, MRD status, and prognosis of adult B-ALL based on a large real-world cohort of 486 patients during a 10-year period.

RESULTS.—

MRD assessed by MFC and polymerase chain reaction (PCR) assays for BCR-ABL+ patients showed concordant results in 74.2% of cases. MRD- status by our MFC panel could clearly predict a favorable relapse-free survival (RFS) and overall survival (OS) both at the end of induction and at the end of 1 consolidation course. Patients with continuous MRD- and with at least 1 MRD- result showed a favorable RFS and OS compared with those with at least 1 MRD+ result and continuous MRD+, respectively.

CONCLUSIONS.—

The single-tube 8-color MFC panel demonstrated a low cost, decent sensitivity, and comparability with polymerase chain reaction-MRD but an excellent performance in predicting RFS and OS, and thus could potentially be taken as a routine indicator in the evaluation of the treatment response for adult patients with B-ALL.

Tracing back of relapse clones by Ig/TCR gene rearrangements reveals complex patterns of recurrence in pediatric acute lymphoblastic leukemia

INTRODUCTION

Relapse remained the major obstacle to improving the prognosis of children with acute lymphoblastic leukemia (ALL). This study aimed to investigate the changing patterns of Ig/TCR gene rearrangements between diagnosis and relapse and the clinical relevance and to explore the mechanism of leukemic relapse.

METHODS

Clonal Ig/TCR gene rearrangements were screened by multiplex PCR amplification in 85 paired diagnostic and relapse bone marrow (BM) samples from children with ALL. The new rearrangements presented at relapse were quantitatively assessed by the RQ-PCR approach targeting the patient-specific junctional region sequence in 19 diagnostic samples. The relapse clones were further back-traced to diagnostic and follow-up BM samples from 12 patients.

RESULTS

Comparison of Ig/TCR gene rearrangements between diagnosis and relapse showed that 40 (57.1%) B-ALL and 5 (33.3%) T-ALL patients exhibited a change from diagnosis to relapse, and 25 (35.7%) B-ALL patients acquired new rearrangements at relapse. The new relapse rearrangements were present in 15 of the 19 (78.9%) diagnostic samples as shown by RQ-PCR, with a median level of 5.26 × 10-2 . The levels of minor rearrangements correlated with B immunophenotype, WBC counts, age at diagnosis, and recurrence time. Furthermore, back-tracing rearrangements in 12 patients identified three patterns of relapse clone dynamics, which suggested the recurrence mechanisms not only through clonal selection of pre-existing subclones but also through an ongoing clonal evolution during remission and relapse.

CONCLUSION

Backtracking Ig/TCR gene rearrangements in relapse clones of pediatric ALL revealed complex patterns of clonal selection and evolution for leukemic relapse.

Molecular characterization of TCF3::PBX1 chromosomal breakpoints in acute lymphoblastic leukemia and their use for measurable residual disease assessment

The translocation t(1;19)(q23;p13) with the resulting chimeric TCF3::PBX1 gene is the third most prevalent recurrent chromosomal translocation in acute lymphoblastic leukemia and accounts for 3-5% of cases. The molecular background of this translocation has been incompletely studied, especially in adult cases. We characterized the chromosomal breakpoints of 49 patients with TCF3::PBX1 and the corresponding reciprocal PBX1::TCF3 breakpoints in 15 cases at the molecular level, thus providing an extensive molecular overview of this translocation in a well-defined study patient population. Breakpoints were found to be remarkably clustered not only in TCF3 but also in PBX1. No association with DNA repeats or putative cryptic recombination signal sequence sites was observed. A simplified detection method for breakpoint identification was developed and the feasibility of patient-specific chromosomal break sites as molecular markers for detecting measurable residual disease (MRD) was explored. A highly sensitive generic real-time PCR for MRD assessment using these breakpoint sequences was established that could serve as a useful alternative to the classical method utilizing rearranged immune gene loci. This study provides the first extensive molecular data set on the chromosomal breakpoints of the t(1;19)/TCF3::PBX1 aberration in adult ALL. Based on the obtained data a generic MRD method was developed that has several theoretical advantages, including an on average higher sensitivity and a greater stability of the molecular marker in the course of disease.

Minimal Residual Disease in Multiple Myeloma: Past, Present, and Future

Responses to treatment have improved over the last decades for patients with multiple myeloma. This is a consequence of the introduction of new drugs that have been successfully combined in different clinical contexts: newly diagnosed, transplant-eligible or ineligible patients, as well as in the relapsed/refractory setting. However, a great proportion of patients continue to relapse, even those achieving complete response, which underlines the need for updated response criteria. In 2014, the international myeloma working group established new levels of response, prompting the evaluation of minimal residual disease (MRD) for those patients already in complete or stringent complete response as defined by conventional serological assessments: the absence of tumor plasma cells in 100,000 total cells or more define molecular and immunophenotypic responses by next-generation sequencing and flow cytometry, respectively. In this review, we describe all the potential methods that may be used for MRD detection based on the evidence found in the literature, paying special attention to their advantages and pitfalls from a critical perspective.

The evolution of minimal residual disease: key insights based on a bibliometric visualization analysis from 2002 to 2022

Background

The topic of minimal residual disease (MRD) has emerged as a crucial subject matter in the domain of oncology in recent years. The detection and monitoring of MRD have become essential for the diagnosis, treatment, and prognosis of various types of malignancy.

Aims

The purpose of this study is to explore the research trends, hotspots, and frontiers of MRD in the last two decades through bibliometric analysis.

Methods

We employed Web of Science databases to carry out a bibliometric visualization analysis of research on 8,913 academic papers about MRD research from 2002 to 2022. VOSviewer, CiteSpace, RStudio, and a bibliometric online analysis platform were mainly used to conduct co-occurrence analysis and cooperative relationship analysis of countries/regions, institutions, journals, and authors in the literature. Furthermore, co-occurrence, co-citation, and burst analyses of keyword and reference were also conducted to generate relevant knowledge maps.

Results

In the past 20 years, the number of MRD research papers has presented an overall rising trend, going through three stages: a plateau, development, and an explosion. The output of articles in the United States was notably superior and plays a dominant role in this field, and the Netherlands had the highest average citation per article. The most productive and influential institution was the University of Texas MD Anderson Cancer Center. Blood published the most papers and was the most cited journal. A collection of leading academics has come to the fore in the research field, the most prolific of which is Kantarjian HM. It was found that the application of MRD in "acute myeloid leukemia", "acute lymphoblastic leukemia", "multiple myeloma", as well as the detection technology of MRD, are the research hotspots and frontiers in this domain. Furthermore, we analyzed the co-citation network of references and found that the top 10 co-cited references were all associated with MRD in hematological malignancies.

Conclusion

This bibliometric visualization analysis conducted a thorough exploration into the research hotspots and trends in MRD from 2002 to 2022. Our findings can aid researchers in recognizing possible collaborations, guiding future research directions, and fostering the growth of MRD detection and monitoring technologies.

Defining the landscape of circular RNAs in neuroblastoma unveils a global suppressive function of MYCN

Circular RNAs (circRNAs) are a regulatory RNA class. While cancer-driving functions have been identified for single circRNAs, how they modulate gene expression in cancer is not well understood. We investigate circRNA expression in the pediatric malignancy, neuroblastoma, through deep whole-transcriptome sequencing in 104 primary neuroblastomas covering all risk groups. We demonstrate that MYCN amplification, which defines a subset of high-risk cases, causes globally suppressed circRNA biogenesis directly dependent on the DHX9 RNA helicase. We detect similar mechanisms in shaping circRNA expression in the pediatric cancer medulloblastoma implying a general MYCN effect. Comparisons to other cancers identify 25 circRNAs that are specifically upregulated in neuroblastoma, including circARID1A. Transcribed from the ARID1A tumor suppressor gene, circARID1A promotes cell growth and survival, mediated by direct interaction with the KHSRP RNA-binding protein. Our study highlights the importance of MYCN regulating circRNAs in cancer and identifies molecular mechanisms, which explain their contribution to neuroblastoma pathogenesis.

Anthracycline-Free Protocol for Favorable-Risk Childhood ALL: A Noninferiority Comparison Between Malaysia-Singapore ALL 2003 and ALL 2010 Studies

PURPOSE

To investigate whether, for children with favorable-risk B-cell precursor ALL (BCP-ALL), an anthracycline-free protocol is noninferior to a modified Berlin-Frankfurt-Muenster ALL-IC2002 protocol, which includes 120 mg/m² of anthracyclines.

PATIENTS AND METHODS

Three hundred sixty-nine children with favorable-risk BCP-ALL (age 1-9 years, no extramedullary disease, and no high-risk genetics) who cleared minimal residual disease (≤0.01%) at the end of remission induction were enrolled into Ma-Spore (MS) ALL trials. One hundred sixty-seven standard-risk (SR) patients (34% of Malaysia-Singapore ALL 2003 study [MS2003]) were treated with the MS2003-SR protocol and received 120 mg/m² of anthracyclines during delayed intensification while 202 patients (42% of MS2010) received an anthracycline-free successor protocol. The primary outcome was a noninferiority margin of 1.15 in 6-year event-free survival (EFS) between the MS2003-SR and MS2010-SR cohorts.

RESULTS

The 6-year EFS of MS2003-SR and MS2010-SR (anthracycline-free) cohorts was 95.2% ± 1.7% and 96.5% ± 1.5%, respectively (P = .46). The corresponding 6-year overall survival was 97.6% and 99.0% ± 0.7% (P = .81), respectively. The cumulative incidence of relapse was 3.6% and 2.6%, respectively (P = .42). After adjustment for race, sex, age, presenting WBC, day 8 prednisolone response, and favorable genetic subgroups, the hazard ratio for MS2010-SR EFS was 0.98 (95% CI, 0.84 to 1.14; P = .79), confirming noninferiority. Compared with MS2003-SR, MS2010-SR had significantly lower episodes of bacteremia (30% v 45.6%; P = .04) and intensive care unit admissions (1.5% v 9.5%; P = .004).

CONCLUSION

In comparison with MS2003-SR, the anthracycline-free MS2010-SR protocol is not inferior and was less toxic as treatment for favorable-risk childhood BCP-ALL.

Long-term outcome in patients with mantle cell lymphoma following high-dose therapy and autologous stem cell transplantation

BACKGROUND

Long-term clinical and molecular remissions in patients with mantle cell lymphoma (MCL) after autologous stem cell transplantation (ASCT) have been evaluated in only a few studies.

DESIGN AND METHODS

Sixty-five patients with MCL received ASCT (54 first-line ASCT, 10 second-line ASCT, and 1 third-line ASCT). In the case of long-term remission (≥5 years; n = 27), peripheral blood was tested for minimal residual disease (MRD) by t(11;14)- and IGH-PCR at the last follow-up.

RESULTS

Ten-year overall survival (OS), progression-free survival (PFS), and freedom from progression (FFP) after first-line ASCT were 64%, 52%, and 59% versus after second-line ASCT 50%, 20%, and 20%, respectively. Five-year OS, PFS, and FFP for the first-line cohort were 79%, 63%, and 69%, respectively. Five-year OS, PFS, and FFP after second-line ASCT were 60%, 30%, and 30%, respectively. Treatment-related mortality (3 months after ASCT) was 1.5%. So far 26 patients developed sustained long-term clinical and molecular complete remissions of up to 19 years following ASCT in first treatment line.

CONCLUSION

Sustained long-term clinical and molecular remissions are achievable following ASCT.