Minimal Residual Disease Reduction Research Articles

The role of blinatumomab in the treatment of B-cell relapses of acute lymphoblastic leukemia in children: own experience

Acute lymphoblastic leukemia (ALL) is the most common malignancy in children. Despite remarkable improvements in the treatment of pediatric acute lymphoblastic leukemia over last years, relapse still carries a poor prognosis with considerable morbidity and mortality. New immunotherapeutic approaches will change the way we treated our patients and the results we had. Blinatumomab is a bispecific T-cell-engaging antibody indicated for the treatment of relapsed/refractory B-cell lymphoblastic leukemia. The use of Blinatumomab in relapsed B-cell ALL has shown promising effects, especially as a bridging tool to hematopoietic stem cell transplantation. The therapy results for patients in the high risk group remain far from optimal due to refractoriness to chemotherapy, death from infectious complications, as well as acute chemotherapy toxicity. This article demonstrates the results of our experience of using Blinatumomab in children with the high-risk group relapsed B-cell ALL treated according to the ALL-REZ 2016 protocol. The study was approved by the Independent Ethics Committee and the Scientific Council of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology. The efficacy and toxicity of innovational blocks with the use of fludarabine and clofarabine with subsequent Blinatumomab infusion are shown. And we present the efficacy of autologous CD3+ lymphocytes infusion once a week during the continuous blinatumomab therapy. Also we demonstrate the results of using Blinatumomab for the treatment of patients with refractory to the first line therapy relapsed B-lymphoblastic leukemia and patients with a second relapse of B-cell ALL. The first line therapy in these patients was carried out according to the ALL-REZ 2014 protocol. Our results show an improved reduction in minimal residual disease in patients with refractory relapsed B-cell ALL as well as an increased event free survival in children with the high-risk group relapsed B-cell ALL.

Impact of autologous hematopoietic cell transplantation on disease burden quantified by next-generation sequencing in multiple myeloma treated with quadruplet therapy.

The incremental impact of autologous hematopoietic cell transplantation (AHCT) on disease burden with quadruplet induction in newly diagnosed multiple myeloma (NDDM) can be reappraised with the serial assessment of minimal residual disease (MRD). We describe the impact of AHCT on MM burden assessed by next-generation sequencing (NGS) for patients enrolled in a clinical trial utilizing quadruplet induction, AHCT, followed by MRD-adapted consolidation. We describe quantitative changes in MRD burden with AHCT and explore patient and disease features influencing the magnitude of MRD reduction with AHCT. Among 123 included patients, 109 underwent AHCT and had MRD assessment pre and post AHCT. Forty percent achieved MRD < 10-5 post-induction, increasing to 70% after AHCT. Of the 65 patients (60%) who remained MRD positive post-induction, 54 (83%) had a reduction in MRD burden with AHCT. The median reduction in MRD with AHCT was 1.10 log10 (range, -1.26 to 3.41). Patients with high-risk cytogenetic abnormalities (HRCA) had greater reduction in MRD burden (p=.02) after AHCT. Median relative reduction was 0.91 log10 (range, -0.75 to 2.14), 1.26 log10 (range, -0.21 to 3.26) and 1.34 log10 (range, -1.28 to 3.41) for patients with 0, 1 and 2+ HRCA, respectively. The presence of HRCA was the only factor associated with greater than 1 log10 reduction in MRD burden with AHCT. Serial NGS MRD demonstrates the incremental effect of AHCT in MM marrow burden in the context of quadruplet induction, particularly in high-risk MM.

Prognostic significance of IKZF1 deletions and IKZF1plus profile in children with B-cell precursor acute lymphoblastic leukemia treated according to the ALL-IC BFM 2009 protocol.

The strongest predictors of outcome in pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL) are minimal residual disease (MRD) and specific molecular abnormalities. One unfavorable prognostic factor is the presence of IKZF1 gene aberrations, particularly when co-occurring with high MRD level at the end of induction treatment. The present study determines the predictive value of a recently-defined IKZF1-plus (IKZF1plus ) microdeletion profile in 373 children with BCP-ALL treated according to the ALL-intercontinental Berlin-Frankfurt-Munster protocol 2009 protocol. IKZF1-wild type (IKZF1wt ) patients demonstrated lower leukemic burden parameters than those carrying IKZF1 deletion (IKZF1del [n=26, 7.0%]) or IKZF1plus pattern (n=34, 9.1%): (i) median blast percentage at diagnosis (78.0% vs. 86.9% vs. 86.0%; p=0.021); (ii) median MRD level at day 15 of induction protocol (0.3% vs. 2.1% vs. 0.8%; p=0.011); (iii) poor steroid response (7.6% vs. 26.5% vs. 12.5%; p=0.010). Minimal residual disease level at day 33 (MRD33) exceeding 10-4 was more frequently observed in both the IKZF1del and IKZF1plus subgroups than in IKZF1wt patients (n=9 [36.0%] vs. n=13 [41.9%] vs. n=70 [24.0%], p=0.051). IKZF1plus individuals showed a tendency for a lower MRD reduction between day 15 and 33 compared to IKZF1del patients (p=0.124). IKZF1del and IKZF1plus patients showed decreased relapse-free survival (HR [95%CI] for IKZF1wt as reference=2.72 [1.21-6.11] and 2.00 [0.87-4.49], respectively, p=0.023). Both genetic markers including IKZF1del and IKZF1plus microdeletion profile provide additional predictive value of treatment outcome in childhood BCP-ALL and may contribute to more efficient patient stratification; the same is true in MRD guided protocols, which are based on flow cytometric measurements on day 15 of induction protocol.

Biologic Basis of the Impact of Autologous Hematopoietic Cell Transplantation in Multiple Myeloma Treated with Quadruplet Therapy

Biologic Basis of the Impact of Autologous Hematopoietic Cell Transplantation in Multiple Myeloma Treated with Quadruplet Therapy

Minimal Residual Disease Dynamics after Venetoclax-Obinutuzumab Treatment: Extended Off-Treatment Follow-up From the Randomized CLL14 Study.

The CLL14 study has established one-year fixed-duration treatment of venetoclax and obinutuzumab (Ven-Obi) for patients with previously untreated chronic lymphocytic leukemia. With all patients off treatment for at least three years, we report a detailed analysis of minimal residual disease (MRD) kinetics and long-term outcome of patients treated in the CLL14 study. Patients were randomly assigned to receive six cycles of obinutuzumab with 12 cycles of venetoclax or 12 cycles of chlorambucil (Clb-Obi). Progression-free survival (PFS) was the primary end point. Key secondary end points included rates of undetectable MRD and overall survival. To analyze MRD kinetics, a population-based growth model with nonlinear mixed effects approach was developed. Of 432 patients, 216 were assigned to Ven-Obi and 216 to Clb-Obi. Three months after treatment completion, 40% of patients in the Ven-Obi arm (7% in the Clb-Obi arm) had undetectable MRD levels < 10-6 by next-generation sequencing in peripheral blood. Median MRD doubling time was longer after Ven-Obi than Clb-Obi therapy (median 80 v 69 days). At a median follow-up of 52.4 months, a sustained significant PFS improvement was observed in the Ven-Obi arm compared with Clb-Obi (median not reached v 36.4 months; hazard ratio 0.33; 95% CI, 0.25 to 0.45; P < .0001). The estimated 4-year PFS rate was 74.0% in the Ven-Obi and 35.4% in the Clb-Obi arm. No difference in overall survival was observed (hazard ratio 0.85; 95% CI, 0.54 to 1.35; P = .49). No new safety signals occurred. Appearance of MRD after Ven-Obi is significantly slower than that after Clb-Obi with more effective MRD reduction. These findings translate into a superior long-term efficacy with the majority of Ven-Obi-treated patients remaining in remission.

Time point-dependent concordance and prognostic significance of flow cytometry and real time quantitative PCR for measurable/minimal residual disease detection in acute myeloid leukemia with t(8;21)(q22;q22.1).

Flow cytometry (FCM) and PCR are reliable methods for assessing minimal residual disease (MRD) in acute myeloid leukemia with t(8;21)(q22;q22.1). The aim of this study was to analyze the concordant rate of these two methods and their prognostic significance. PCR and FCM were simultaneously used for MRD analysis at four different time points on 450 BM samples from 124 patients with AML with t(8;21)(q22;q22.1). The four monitoring time points included post-induction (first), after the first consolidation (second) and the second consolidation (third), and at the end of chemotherapy or before Allo/Auto stem cell transplantation (fourth). The concordant rates of the two methods were 33.06%, 25.81%, 49.59%, and 75.31%, respectively, and the main discordant cases were FCM-/PCR+ cases. At all monitoring time points, the MRD level ≥ 10-4 by FCM indicated a poor 3-year Relapse-Free Survival (RFS) (p < 0.001). More than 2-log MRD reduction by PCR after induction and more than 3-log reduction by PCR after the first consolidation remained the significant predictors of better RFS (p < 0.001). After the second consolidation, the negative MRD by PCR (<10-5) was also associated with improved RFS (p=0.002). A > 1-log increase in PCR can effectively predict recurrence after molecular remission (p < 0.001). In the multivariate analysis, MRD≥0.01% by. FCM and less than 2-log MRD reduction by PCR after induction remained the significant predictors of poor RFS (p < 0.05). FCM+ always indicates a poor prognosis. Sequential monitoring by PCR is of significance for evaluating prognosis. Our findings suggest a complementary role of two analyses in optimizing risk stratification in clinical practice.

Blinatumomab in Pediatric Acute Lymphoblastic Leukemia-From Salvage to First Line Therapy (A Systematic Review).

Acute lymphoblastic leukemia is by far the most common malignancy in children, and new immunotherapeutic approaches will clearly change the way we treat our patients in future years. Blinatumomab is a bispecific T-cell-engaging antibody indicated for the treatment of relapsed/refractory acute lymphoblastic leukemia (R/R-ALL). The use of blinatumomab in R/R ALL has shown promising effects, especially as a bridging tool to hematopoietic stem cell transplantation. For heavily pretreated patients, the response to one or two cycles of blinatumomab ranges from 34% to 66%. Two randomized controlled trials have very recently demonstrated an improved reduction in minimal residual disease as well as an increased survival for patients treated with blinatumomab compared to standard consolidation treatment in first relapse. Current trials using blinatumomab frontline for high-risk patients or as a consolidation treatment post-transplant will show whether efficacy is even higher in less heavily pretreated patients. Due to the distinct pattern of adverse events compared to high-dose conventional chemotherapy, blinatumomab could play an important role for patients with a risk for severe chemotherapy-associated toxicities. This systematic review discusses all published results for blinatumomab in children as well as all ongoing clinical trials.

Log reduction of leukemic cells and minimal residual disease by flow cytometry represent effective predictors of clinical outcome in elderly patients with acute myeloid leukemia.

Nowadays minimal residual disease (MRD) and log-reduction of leukemic cells are poorly investigated in elderly patients with acute myeloid leukemia (AML) treated with hypometilating agents (HMAs). Studies focusing on MRD in elderly AML patients who received HMAs are scant and devoid of rigorous criteria for both enrollment and monitoring. Log-reduction has never been investigated in these patients. Thus, the purpose of our study was to compare the prognostic impact of MRD and log-reduction of leukemic cells at the optimal time of assessment in older AML patients. Elderly patients who completed at least six cycles of HMAs and showed suitable leukemia-associated immunophenotypes (LAIPs) for the MRD and log-reduction assessment by flow cytometry were enrolled in the study. After comparing the times of assessment C4 (4-cycles) and C6 (6-cycles), C6 has been chosen as optimal. Patients who achieved MRD negativity or 2-log-reduction of leukemic cells at C6 had a significantly longer DFS. Particularly, results of 2-log-reduction were confirmed a multivariate analysis. Patients with MRD negativity or 2-log reduction of leukemic cells showed an improvement of their OS, although not significantly. Our data confirmed the predictive role of MRD and 2-log reduction also in older AML patients treated with HMAs.

The Impact of DNMT3A Status on NPM1 MRD Predictive Value and Survival in Elderly AML Patients Treated Intensively.

Simple SummaryDNMT3A mutation has been associated with adverse outcomes. In this study, we aimed to investigate the impact of DNMT3A status on NPM1 MRD predictive value for survival in a retrospective cohort of acute myeloid leukemia (AML) patients aged over 60 years old treated intensively. A total of 138 patients treated for NPM1-mutated AML in two French institutions were analyzed retrospectively. A 4log reduction of NPM1 MRD was associated with a better outcome. DNMT3A negative patients who achieved a 4log reduction had a superior outcome to those who did not. However, postinduction NPM1 MRD1 reduction was not predictive of OS and LFS in DNMT3Amut patients. These results confirm that post-induction NPM1 MRD1 is a reliable tool to assess disease outcome in elderly AML patients. However, the presence of DNMT3A also identify a subgroup of patients at high risk of relapse.Minimal residual disease (MRD) is now a powerful surrogate marker to assess the response to chemotherapy in acute myeloid leukemia (AML). DNMT3A mutation has been associated with adverse outcomes. In this study, we aimed to investigate the impact of DNMT3A status on NPM1 MRD predictive value for survival in a retrospective cohort of AML patients aged over 60 years old treated intensively. A total of 138 patients treated for NPM1-mutated AML in two French institutions were analyzed retrospectively. DNMT3A status did not influence the probability of having a ≥ 4log MRD1 reduction after induction. Only 20.4% of FLT3-ITD patients reached ≥ 4log MRD1 reduction compared to 47.5% in FLT3wt cases. A 4log reduction of NPM1 MRD was associated with a better outcome, even in FLT3-ITD mutated patients, independent of the allelic ratio. DNMT3A negative patients who reached a 4log reduction had a superior outcome to those who did not (HR = 0.23; p < 0.001). However, postinduction NPM1 MRD1 reduction was not predictive of OS and LFS in DNMT3Amut patients. These results confirm that post-induction NPM1 MRD1 is a reliable tool to assess disease outcome in elderly AML patients. However, the presence of DNMT3A also identifies a subgroup of patients at high risk of relapse.

Minimal Residual Disease in Acute Lymphoblastic Leukemia: Current Practice and Future Directions.

Simple SummaryAcute lymphoblastic leukemia minimal residual disease (MRD) refers to the presence of residual leukemia cells following the achievement of complete remission, but below the limit of detection using conventional morphologic assessment. Up to two thirds of children may have MRD detectable after induction therapy depending on the biological subtype and method of detection. Patients with detectable MRD have an increased likelihood of relapse. A rapid reduction of MRD reveals leukemia sensitivity to therapy and under this premise, MRD has emerged as the strongest independent predictor of individual patient outcome and is crucial for risk stratification. However, it is a poor surrogate for treatment effect on long term outcome at the trial level, with impending need of randomized trials to prove efficacy of MRD-adapted interventions.Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer and advances in its clinical and laboratory biology have grown exponentially over the last few decades. Treatment outcome has improved steadily with over 90% of patients surviving 5 years from initial diagnosis. This success can be attributed in part to the development of a risk stratification approach to identify those subsets of patients with an outstanding outcome that might qualify for a reduction in therapy associated with fewer short and long term side effects. Likewise, recognition of patients with an inferior prognosis allows for augmentation of therapy, which has been shown to improve outcome. Among the clinical and biological variables known to impact prognosis, the kinetics of the reduction in tumor burden during initial therapy has emerged as the most important prognostic variable. Specifically, various methods have been used to detect minimal residual disease (MRD) with flow cytometric and molecular detection of antigen receptor gene rearrangements being the most common. However, many questions remain as to the optimal timing of these assays, their sensitivity, integration with other variables and role in treatment allocation of various ALL subgroups. Importantly, the emergence of next generation sequencing assays is likely to broaden the use of these assays to track disease evolution. This review will discuss the biological basis for utilizing MRD in risk assessment, the technical approaches and limitations of MRD detection and its emerging applications.

Optimized clinical application of minimal residual disease in acute myeloid leukemia with RUNX1–RUNX1T1

Minimal residual disease (MRD) levels monitored by polymerase chain reaction are associated with outcomes in acute myeloid leukemia with RUNX1-RUNX1T1. The objectives of our study were to quantitatively compare the predictive value of MRD reduction and absolute copies and assess the influence of other prognostic factors on MRD. A total of 224 consecutive patients with RUNX1-RUNX1T1 aged ≤55 years were included in the MRD study. Patients received different induction regimens including conventional- or intermediate-dose cytarabine plus low-dose daunorubicin and omacetaxine mepesuccinate or daunorubicin at 60 mg/m2/day on days 1-3. As continuous variables, both MRD reduction and absolute MRD level were significantly associated with cumulative incidence of relapse (CIR; hazard ratio [HR] = 1.610, 95% confidence interval [CI]: 1.370-1.890, p < 0.001, and HR = 1.170, 95% CI: 1.120-1.230, p < 0.001, respectively). For the CIR, the area under the curves (AUCs) of MRD reduction and absolute MRD level after the first consolidation chemotherapy were 0.629 and 0.629, respectively. Intermediate-dose cytarabine induction (HR = 0.494; p = 0.039 for CIR, HR, 0.451; p = 0.014 for RFS, and HR, 0.262; p = 0.006 for OS) remained significantly associated with outcomes after adjusting for MRD reduction after the first consolidation therapy (HR = 1.456, p < 0.001, for CIR; HR = 1.467, p = 0.001, for relapse-free survival; and HR = 1.468, p = 0.014, for overall survival) in multivariate analyses. In conclusion, the prognostic significance of MRD after the first consolidation therapy was influenced by the induction regimen in acute myeloid leukemia with RUNX1-RUNX1T1.

Clofarabine Significantly Increases Eradication of Minimal Residual Disease of B-Precursor ALL Compared to High-Dose Cytarabine in Randomized Trial Coall 08-09

Background Since the FDA approval of clofarabine for the treatment of relapsed or refractory acute lymphoblastic leukemia (ALL) at childhood, several studies have been launched which put clofarabine under scrutiny in combination with other cytostatic drugs as second or third line therapy. As a novel treatment-strategy we introduced the combination of clofarabine with pegylated asparaginase (PEG-ASP) in a randomized fashion in comparison to the standard consolidation course with high dose cytarabine (Hidac) combined with PEG-ASP into the frontline management of ALL within the CoALL 08-09 protocol. The primary objective of the study was to compare the MRD based assessment of the cytotoxic efficacy of the randomized courses in pediatric ALL. Patients and methods CoALL 08-09 was an open, interventional, multi-center, prospective, and randomized clinical trial for patients with newly diagnosed ALL. In March 2010 the trial had been opened for enrollment of patients under 18 years with confirmed diagnosis of acute B- or T-cell precursor leukemia. After a stratified phase I/II, in which patients with high-risk features and high post-induction MRD received the combination of clofarabine and PEG-ASP, the randomized trial started in November 2013. All patients with a measurable MRD at the end of induction (EOI), as measured by RQ-PCR according to EURO-MRD guidelines, were eligible for randomization to receive either the combination of clofarabine 5 x 40 mg/m2 or high dose cytarabine (HIDAC) 4 x 3g/m2 bothin combination with PEG-ASP 2.500 IU/m2 at the beginning of the consolidation phase. Until December 2019 303 study patients were randomized allocating 151 patients towards the clofarabine and 152 patients to the HIDAC arm. Patient characteristics and MRD burden prior to this treatment element were highly comparable. Results The reduction of minimal residual disease was significantly more profound after clofarabine compared to cytarabine (p(Cochran-Armitage)=.01 for BCP-ALL with 93 vs 79 patients reaching MRD negativity (Table 1). MRD status of BCP-ALL after the first randomized consolidation block (day 50) was of prognostic relevance with a statistically significant impact on EFS and relapse rate (Fig. 2a). However, no difference in outcome regarding the event-free and overall survival between the randomized arms was observed (5-year EFS: Clofarabine 85.7, SE=4.1 vs Hidac 84.8, SE=4.7 (p=.96) and OS: 95.7, SE=1.9 vs 92.2, SE=3.2(p=.59) Fig. 2b). This finding was recapitulated independent of gender, age, WBC count at diagnosis, ETV6-RUNX 1 translocation, immunophenotype or overall risk strata). Results for T-ALL patients are in the same range but because of small numbers not statistically significant. No differences in the incidence of severe or persistent toxicity btween randomized treatment elements as well as in the subsequent treatment realization were registered. Conclusion Clofarabine combined with PEG-asparaginase is highly effective and well tolerated in the frontline treatment of ALL. Although the prognostic impact of MRD is still discernible in early consolidation, the greater cytotoxic efficacy of clofarabine reflected by a more frequent eradication of MRD, did not translate into an apparent improvement of outcome likely due to a lack of power in the comparative analysis of randomized patients. Disclosures No relevant conflicts of interest to declare.

Interim Results of a First in Man Study with the Fc-Optimized FLT3 Antibody Flysyn for Treatment of Acute Myeloid Leukemia with Minimal Residual Disease

Background: Substantial surface expression of the FLT3 receptor can be measured on blast cells in 70% to 100% of acute myeloid leukemia (AML) patients, while no or only low levels are expressed on healthy cells like monocytes and progenitor stem cells. Thus, FLT3 is a suitable and highly selective target for therapeutic antibodies. FLYSYN is a chimeric Fc-optimized IgG1 antibody and binds specifically and with high avidity to human FLT3 (CD135). Despite achievement of complete remission, roughly half of AML patients display minimal residual disease (MRD) after end of therapy and relapse. Methods: We perform an open-label, single-arm, first in man multicenter trial to assess safety and tolerability as well as preliminary efficacy of FLYSYN as monotherapy in adult (≥18 years) AML patients in complete remission with MRD (NCT02789254). FLYSYN is administered as IV infusion over a 3 hour period. Recruitment started in March 2017 with an estimated maximum number of 31 patients and estimated recruitment until January 2020. The main inclusion criterion was confirmed stable or increasing MRD positivity in two sequential measurements. MRD was measured by central RT-qPCR and/or next generation sequencing (NGS). Sensitivity with RT-qPCR (for NPM1 only) was 10-6 and 10-4 with NGS. Patients with acute promyelocytic leukemia as well as prior hematopoietic stem cell transplantation were excluded. Using a "3 + 3" dose escalation design, five of the planned six cohorts with escalating doses have currently completed treatment (cohort 1: 0.5 mg/m² BSA; cohort 2: 1.5 mg/m² BSA; cohort 3: 5 mg/m² BSA; cohort 4: 15 mg/m² BSA; cohort 5: 45 mg/m²; cohort 6: in total 45 mg/m²; 15 mg/m² on day 1, 15 and 29). Three patients were treated per cohort, except for cohort 4, which was expanded to nine patients. The interim analysis for preliminary efficacy was performed after 18 patients were treated in cohorts 1-4. Response is defined as 1 log MRD reduction. Results: Median age was 60 years (range, 21-80 years). Sixteen patients were MRD positive for NPM1 and one patient each for RUNX1-RUNX1T1 and IDH2. So far, FLYSYN was well tolerated. Only one temporary grade 3 adverse event (AE) occurred (neutrophil decrease on day 3 only) in a patient of cohort 3, which was suspected to be related to FLYSYN treatment. There were no reported dose-limiting toxicities. The most frequently reported AEs were grade 1 and 2 gastrointestinal toxicities and laboratory abnormalities, which all were manageable with supportive care. After treatment, neither human anti-mouse nor anti-human antibodies were detected in any of the patients. Preliminary pharmacokinetic analysis was performed in the first 12 patients of the study and revealed a half-life of FLYSYN of roughly 6.5 days. Regarding preliminary efficacy, 1 patient of cohort 1 achieved permanent MRD negativity in bone marrow (BM; lasting until day 545) and 1 patient a temporary BM MRD reduction (at day 15). One patient of cohort 2 achieved BM MRD negativity (day 22) with MRD progression on day 365, whereas the other 2 patients were BM MRD progressive. None of the patients of cohort 3 achieved a MRD response in BM, but 2 patients achieved a temporary MRD response in peripheral blood. Four patients of cohort 4 achieved non-permanent BM MRD negativity. Overall, 6 patients achieved BM MRD negativity (33 %, 6/18), enduring more than 1 year in 1 patient. Conclusions: Our data suggest that FLYSYN is safe and very well tolerated as monotherapy in MRD positive AML patients. Preliminary efficacy data are promising, and recruiting is ongoing in cohort 6 in which 15 mg/m² FLYSYN is given for three times. Up-dated results will be presented at the ASH meeting. Disclosures Heuser: Bayer Pharma AG, Berlin: Research Funding; Synimmune: Research Funding. Müller-Tidow:MSD: Membership on an entity's Board of Directors or advisory committees. Steiner:Synimmune: Employment, Other: shareholder interest. Grosse-Hovest:SYNIMMUNE: Employment, Other: shareholder interest. Jung:Synimmune: Other: shareholder interest. Salih:SYNIMMUNE: Consultancy, Research Funding.

Hematopoietic stem cell transplantation for children with acute myeloid leukemia in second remission: A report from the Australasian Bone Marrow Transplant Recipient Registry and the Australian and New Zealand Children's Haematology Oncology Group.

Approximately one-third of children with acute myeloid leukemia (AML) relapse, requiring re-treatment and allogeneic hematopoietic stem cell transplantation (HSCT). Although achieving second complete remission (CR2) prior to HSCT is desirable, once CR2 is attained, it is unclear if there is any benefit from further chemotherapy prior to HSCT. Moreover, although pre-HSCT minimal residual disease (MRD) has prognostic value in acute lymphoblastic leukemia, the benefit of MRD reduction after achieving CR prior to HSCT is less clear for AML. To address these questions, we analyzed data from pediatric transplant centers in Australia and New Zealand concerning relapsed childhood AML cases occurring between 1998 and 2013. Given the retrospective nature of our analysis and assay data available, we analyzed patients on the basis of measurable residual disease (MeRD) by any methodology, rather than MRD in the conventional sense. We observed improved overall survival (OS) in children receiving two chemotherapy cycles, compared to one cycle or three or more cycles pre-HSCT. Improved OS with two cycles remained significant for patients without MeRD after cycle 1. These data suggest that a second chemotherapy cycle pre-HSCT may improve survival by lowering disease burden. Prospective trials assessing strategies to reduce pre-HSCT MRD in relapsed childhood AML are warranted.

Successful of Chemo-Free Treatment with Dasatinib and Blinatumomab in a Pediatric EBF1-PDGFRβ Positive Acute Lymphoblastic Leukemia

Recently, a novel subgroup of B Cell Precursor (BCP) Acute Lymphoblastic Leukemia (ALL), called Philadelphia-like (Ph-like) ALL, has been described. This high-risk group, despite the absence of BCR-ABL1 rearrangement, shows genomic abnormalities that result in aberrant expression of cytokine receptors genes or tyrosine-kinase-activating signaling. These patients are poor responder to conventional chemotherapy but potentially sensitive to Tyrosine-Kinase Inhibitors (TKIs).Herein we report the case of a 10 year-old girl who received diagnosis of precursor B-ALL on February 2018. She started therapy according to observational protocol ALL 2017 of the Italian Association of Pediatric Hemato-Oncology (AIEOP). After pre-phase, the patient resulted prednisone poor responder and continued induction therapy, including daunorubicin, vincristine, PEG-L-Asparaginase, prednisone and intrathecal methotrexate. Bone marrow evaluation showed persistence of disease on day 15 (88% of lymphoblasts) and 33 (60% of blasts) in flow cytometry. At the end of IA induction phase, Minimal Residual Disease (MRD) in RT-PCR showed high positivity (marker 1 = 7.2x10-1, marker 2= 8.11x10-1). At this time, further molecular studies, using RNA targeted next generation sequencing (PanCancer, Illumina), revealed the presence of EBF1-PDGFRβ gene fusion.Since the patient was resistant to conventional therapy and literature's evidences demonstrated potential sensitivity of EBF1-PDGFRβ to TKIs therapy, we decided to add dasatinib, a second generation TKI, to IB induction, with cyclophosphamide, cytarabine and 6-mercapthopurine. After one week of therapy, clinical course was complicated by Klebsiella Pneumoniae sepsis, followed by digestive hemorrhage. Since we retained that the hemorrhagic event could be related to dasatinib, the drug was temporarily discontinued. However, bone marrow evaluation, after only 10 days of dasatinib administration, showed hematologic remission (3% of lymphoblast) and MRD reduction >1 logarithm (markers 1=1-10-2 e markers 2= 9.9 x 10-3).Given the resistance to chemotherapy alone and the excellent response to dasatinib but its related toxicity in combination, we decided to start immunotherapy with blinatumomab, a bi-specific CD3-CD19 monoclonal antibody, alternated to dasatinib, in order to achieve MRD negativity before to proceed with allogeneic hematopoietic stem cell transplantation (HSCT) from HLA-identical sibling. The patient received 2 courses of blinatumomab for 28 days continuous infusion (15 mcg/mq days 1-28), interspersed by 15 days of dasatinib (60 mg/mq/day). After the first cycle the patient achieved complete hematological remission and MRD negativity. MRD negativity was confirmed after first course of dasatinib, second course of blinatumomab and second course of dasatinib. Dasatinib, given alone, was well tolerated and no serious adverse event were reported. Actually, the patient is undergoing HSCT by HLA-identical sister.To our knowledge, only few cases of EBF1-PDGFRβ ALL, treated with TKIs, are described in literature and this is the first in which MRD negativity was obtained with a sequential combination of dasatinib and blinatumumomab, a chemo-free approach, showing efficacy and good tolerability. This case highlights also that screening for targetable lesions at diagnosis or in case of resistance to induction phase is mandatory to identify patients who might benefit from alternative therapies as TKIs, immunotherapy or their combination. A longer follow-up is required to definitively establish the long-term efficacy of this biological approach in our patient. Nevertheless, it is interesting to speculate that alternative treatment with TKIs or immunotherapy could avoid, in the future, an intensive chemotherapy, or probably a transplant approach in selected patients, in order to achieve a durable cure in these Ph-like patients. DisclosuresLocatelli:Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Parasole:Baxalta: Membership on an entity's Board of Directors or advisory committees; behring: Consultancy; jazz: Honoraria, Speakers Bureau.

Different Treatment Regimens, Optimal Time Points and Threshold Level While Minimal Residual Disease Evaluation in AML Patients

Introduction. Minimal residual disease (MRD) detection by multicolor flow cytometry (MFC) after early induction or consolidation AML therapy is a well known factor of adverse prognosis, especially in intermediate risk group. New assessment of response in AML is complete remission with MRD-negative status. However, there is still no standardization of MFC method for AML patients (pts). Optimal time point for MRD status and its threshold value vary in different studies.Aim. To study different consolidation treatment regimens in AML pts by measuring of MRD reduction, to determine optimal time point and threshold level for additional risk stratification.Patients and methods. From March 2016 to February 2018 42 pts (younger than 60 y.o.) with newly diagnosed AML were included in prospective MRD study in hematology department of National Research Center for hematology. Initial leukemia-associated immunophenotype was analysed before any treatment, and bone marrow assessment for MRD detection was performed in CR pts after 1st and 2nd chemotherapy courses. The standard antibody panel included CD19, CD7, CD2, CD38, CD65, CD66b, CD99 (FITC); CD56, CD15, CD11b, CD13 (PE); CD33 (APC); HLA-DR, CD14, CD16, CD117 (PerCP-Cy 5.5); CD45 (APC-H7) and CD34(PE-Cy7). For results record BD FACSCanto II (Becton Dickinson) machine was used. The first course for all pts was the standard «7+3». Before March 2017 the second course was also «7+3» and included 25 pts, after March 2017 - 17 pts received intensive «Flarida» regimen (Fludarabine 30mg/m2 1-4, Ara-C 1g/m2 1-4, Idarubicin 8mg/m2 1,3). The 2nd MRD test was compared in these two groups. There was no difference between the two groups by pts in CR after the first «7+3», ELN status and age.Results. By using of special mathematical and statistical method the threshold value of 0,01% was estimated for long-term prognosis. Two years relapse-free survival (RFS) in MRD-positive (MRD+) and MRD-negative (MRD-) groups after the 1st induction was 23% and 87%, respectively (p<0,01). Probability of relapse (PoR) during the first year of observation in these two groups was 72% and 10%, respectively (p<0,01). After the second course 9 more pts in two groups became MRD-negative and 6 of them developed a relapse. RFS in MRD+ and MRD- after the 2nd course was 36% and 65% (p<0,01), and PoR - 71% and 34%, respectively (p<0,01). Multivariate analysis showed MRD factor as the only important in RFS compared to cytogenetic, molecular status, age and initial leukocyte count. OS and RFS in «7+3» and «Flarida» regimens during the first year were 100% vs 80% (p=0,27) and 74% vs 76% (p=0,63), respectively. MRD level reduction after different consolidation regimens («7+3» vs «Flarida») didn't show any variation (p=0,14) and there was no association between MRD status after induction in different ELN groups (p=0,52).Conclusion. MRD threshold value of 0,01% allows to distinguish the two cohorts of AML pts groups: with different prognosis even in any ELN risk subgroups. The RFS was reliably higher in pts with CR and MRD-negative status right after the first induction, which reflected the chemo sensitivity of the tumor. After the consolidation course MRD detection still has a prognostic value. MRD level reduction was not associated with intensification of chemotherapy. There is a great need to achieve MRD negative status in AML pts after the 1st induction course so new therapy approaches are pending. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Ibrutinib Plus Venetoclax in Relapsed/Refractory CLL: Results of the Bloodwise TAP Clarity Study

Ibrutinib Plus Venetoclax in Relapsed/Refractory CLL: Results of the Bloodwise TAP Clarity Study

C-KIT- Mutated t(8;21)AML Patients with >3log Reduction of MRD Conferred a Very High Relapse and Need HSCT to Improve Outcome

[Objective] Previous studies showed that c-KIT mutation and <3log reduction of minimal residual disease (MRD) were two poor prognostic markers for acute myeloid leukemia (AML) with t(8;21) . However, How to deal with c-KIT- mutated t(8;21)AML patients with >3log reduction of MRD remains undefined. To answer this question, we performed this study.[Methods] The current retrospective study consisted of 70 newly diagnosed patients with c-KIT- mutated t(8;21)AML during July 2005 and March 2016 in Peking University People's Hospital. Induction treatment included standard 3+7' regimen or HAA regimen. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) was recommended to all patients with an available donor after 2-3 cycles of consolidation treatment with high-dose cytarabine(HDAC). Patients without a donor or refusing HSCT received HDAC-based intensive treatment. MRD was determined by RUNX1/RUNX1T1 transcript levels detected by Q-PCR. The last follow-up time was July 2016.[Results] Sixty-nine out of 70 patients achieved complete remission(CR).Two patients relapsed after first cycle of consolidation treatment. There were 60 patients having the results of MRD after 2 cycles of consolidation treatment (Figure 1). Thirty-four patients achieved >3log reduction of RUNX1/RUNX1T1 transcript levels (defined as major molecular remission, MMR). There were 16 and 18 patients finally receiving chemotherapy and allo-HSCT. Twenty-six patients did not achieve MMR, and 12 and 14 patients finally receiving chemotherapy and allo-HSCH, respectively. For patients achieving MMR, the 4-year cumulative incidence of relapse (CIR) and disease-free survival (DFS) were 84.8% vs.6.7% (p<0.001) and 20.6% vs.87.5% (p<0.001) when receiving chemotherapy or allo-HSCT(Figure 2). For patients not achieving MMR, the 4-year CIR and DFS were 100% vs.30.8% (p<0.001) and 0% vs.60% (p<0.001) when receiving chemotherapy or allo-HSCT (Figure 2). Multivariate analysis revealed that MRD status (MMR or non-MMR and treatment choice (HSCT or chemotherapy) were independent prognostic factors for relapse, DFS.[Conclusion] We concluded that c-KIT- mutated t(8;21)AML patients with >3log reduction of MRD conferred a very high relapse and need allo-HSCT to improve outcome. [Display omitted] [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Interim Analysis of Lenalidomide Consolidation on Minimal Residual Disease in Patients with Chronic Lymphocytic Leukemia Following Initial FCR Chemotherapy - CLL6 Residuum Study of the Australian Leukaemia and Lymphoma Group (ALLG) and the French Innovative Leukemia Organization (FILO)

IntroductionPatients with residual disease following initial treatment of chronic lymphocyticleukemia(CLL) withfludarabine, cyclophosphamide and rituximab (FCR) chemotherapy have reduced progression free (PFS) and overall survival (OS). The CLL6 RESIDUUM trial is a joint trial of the Australasian Leukaemia and Lymphoma Group (ALLG) and the French CLL branch of the French InnovativeLeukemiaOrganization (FILO) thatanalyzesthe role oflenalidomide(LEN) as consolidation therapy in patients following front-line treatment for CLL who do not enter minimal residual disease (MRD) negative complete remission.MethodsCLL patients with CIRS score <6 requiring treatment according to iwCLLcriteria receive 6 cycles of FCR. Following completion of treatment, those with clinical, radiological and/or multiparameterflow cytometry (MFC) evidence of residual CLL in blood or bone marrow are randomized 1:1 to receive 2 years of maintenance treatment with LEN 10 mg daily or observation (OBS). Patients are reviewed for evidence of clinical progression, and peripheral blood and bone marrow are sampled regularly for evidence of MRD. CT scans are performed until resolution of lymphadenopathy and splenomegaly. Flow analysis for MRD is performed at two central laboratories using ERIC accredited methodology to achieve a sensitivity of 10-4. The primary end point of the study is time to progression or death.ResultsAs of end of July 2016, data from 79 patients randomized on the study were analyzedfor the effects of consolidation treatment on blood and marrow MRD. Median duration from randomization was 488 days. There were 63 males and 16 females. Median age was 62 years (range 29 to 81). 37 patients were randomized to receive LEN, 42 to OBS .On the LEN arm 13, 3 and 21 patientsvs 12, 9 and 21 on the OBS arm were in CR, nodular PR and PR respectively at the time of randomization. There were 26 serious adverse events (SAEs) reported in 22 patients. 12 SAEs in 11 patients were attributed to LEN including pneumonia/chest infection (n=4), pulmonary infiltrate (1), prostatitis (1) second primary malignancy (SPM) (1), vomiting (1), neutropenia (1), tumorflare (1), acute kidney injury (1) and anal warts (1). There were 5 SAEs in the OBS arm comprising SPM (2), neutropenia (1), gout (1) and GuillainBarre syndrome(1). Peripheral blood samples were analyzedprior to consolidation and at 3, 6 and 12 months and every 6 months thereafter. MRD levels during consolidation were compared with pre-consolidation levels and categorized as increasing, decreasing, stable detectable or stable undetectable (Fig 1). MRD increased over the period of observation in 38% of patient on the LEN arm and in 62% of patients on the OBS arm (p = 0.032, Χ2). 10 patients (27%) in the LEN arm and 2 patients (5%) in the control arm had decreasing levels of MRD in the blood (p = 0.006, Χ2). There was no difference between consolidation treatments in the percentage of patients with stable blood MRD measurements, whether in the detectable or the undetectable range. The effect of LEN was most apparent in patients in PR at randomization where 5 patients (24%) taking LEN had increasing MRD in the blood compared to 15 patients (71%) on the OBS arm (p = 0.002, Χ2). Bone marrow MRD levels were assessed prior to consolidation and after 12 months in 9 patients in each arm of the study (LEN arm 2 CR, 1 nPR, 6 PR; OBS arm 4 CR, 1 nPR, 4 PR at randomization). Eight patients in the LEN arm and 2 patients in the OBS arm were observed to have a reduction in marrow MRD. There was a significant reduction between the 2 time points in the LEN arm (p=0.022 paired Wilcoxon test) but not in the OBS arm. Four of 9 patients in the LEN arm and 1 patient in the OBS arm achieved marrow MRD values below 10-4 after 1 year on trial.ConclusionLEN consolidation therapy for residual disease after FCR front-line therapy for CLL is associated with improved control of MRD in both blood and bone marrow. A large group of recently randomized patients will provide more data to determine whether these encouraging results will translate into improved progression free and overall survival. [Display omitted] DisclosuresGottlieb:Indee: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Abbvie: Membership on an entity's Board of Directors or advisory committees. Aurran:Janssen: Honoraria. Tam:Gilead: Honoraria; Roche: Honoraria; Abbvie: Honoraria; Janssen: Honoraria. Letestu:Roche: Honoraria; Alexion: Honoraria. Levy:Roche: Honoraria; Gilead: Honoraria; Abbive: Honoraria; Janssen: Honoraria. Leblond:Roche: Honoraria; Gilead: Honoraria; Janssen: Honoraria; Abbvie: Honoraria. Mulligan:GSK: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; AbbVie: Consultancy, Honoraria, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau. Cymbalista:Abbvie: Honoraria; Roche: Honoraria; Janssen: Consultancy, Research Funding; Gilead: Consultancy, Honoraria.

Integrating Genetic Risk Factors with Age, Presenting White Cell Count and MRD Response As Continuous Variables to Predict Relapse in Paediatric Acute Lymphoblastic Leukemia (ALL)

▪Paediatric ALL is heterogeneous in terms of clinical presentation, response to therapy and underlying genetic mechanisms. The application of treatment stratification algorithms has resulted in survival rates exceeding 90%. However, current algorithms apply risk factors as binary variables using arbitrary thresholds and in an independent manner. This approach potentially distorts biological heterogeneity resulting in loss of prediction accuracy. Therefore, we sought to determine whether treating clinical risk factors and MRD response as continuous variables and integrating genetic features can refine prognostication.A total of 2542 patients, aged 1-24 years old, recruited to UKALL2003 were available for analysis. NCI standard/high patients were initially assigned to regimen A/B. Sow early responders and those with HR genetics were transferred to the more intensive regimen C. Minimal residual disease (MRD) was evaluated at the end of induction (EOI) by real-time quantitative PCR analysis of Ig/TCR rearrangements. Patients with EOI MRD >0.01% were randomised to stay on regimen A/B or move to C whereas patients with EOI MRD <0.01% were randomised to receive one or two delayed intensifications. Genetic subtypes were defined as good risk (GRcyto: ETV6-RUNX1, high hyperdiploidy), high risk (HRcyto: KMT2A fusions, near haploidy, low hypodiploidy, iAMP21 and TCF3-HLF), intermediate risk (other B cell precursor cases) and T-ALL.In order to examine MRD as a continuous variable, we log transformed the raw EOI MRD value assuming a minimum detection level of 0.00001 and assigned cases with undetectable MRD a value of one log below this threshold. The transformed MRD variable [t(MRD)] followed a log normal distribution (Figure 1). Importantly, this log normal distribution was distinct across the genetic subtypes (Figure 1, p<0.001); even after accounting for the different induction regimens used. Using the t(MRD) variable, we show that each log reduction in EOI MRD reduces the relapse risk (RR) by 22% (p<0.001). In the current UK paediatric trial (UKALL2011) an MRD threshold of 0.005% is used to assign patients to regimen C. Therefore, we examined the RR by MRD value within each genetic subtype. Table 1 shows that the RR for GRcyto patients remains low (<4%) up to an MRD threshold of 0.1% and treatment intensification did not further reduce this RR. In light of these data, we have changed the MRD threshold for classifying newly diagnosed GRcyto patients as MRD risk from 0.005% to 0.1%. This treatment intervention reduces the proportion of GRcyto patients who receive the most intensive therapy (regimen C) from ~40% to <10% and therefore avoids potential unnecessary toxicity.Next we combined multiple significant risk factors from univariate analysis using forward selection modelling to fit a multivariate prognostic model. The final model included log(WCC) and t(MRD) as continuous variables and two binary genetic variables: GRcyto and HRcyto. Using the coefficients from this model, we constructed a linear model which enabled the calculation of individual risk scores. Figure 2 shows the correlation between an individual’s risk score and their RR. To investigate the clinical relevance of this risk score, we generated five risk groups based on ascending RR (Table 2) which have significant differential outcomes (all p<0.001). Using this classification, 65% patients are very low or low (VLR/LR) risk while 11% are high or very high risk (HR/VHR). Although the HR/VHR groups are small their RR was >25% and together with the standard risk (SR) group capture >70% relapses and, importantly, >80% of HR relapses (very early/early relapses). Among the 136 VLR/LR patients who had MRD >0.01%, there was no difference in EFS between patients randomised to regimen A/B v C (97% v 99%, p=0.5). Equally among 470 VLR/LR patients with MRD <0.01%, there was no difference in EFS between patients randomised to receive 1 or 2 delayed intensifications (96% v 96%, p=0.8).In conclusion, we have showed that EOI MRD is log normally distributed but that the shape of the distribution depends on genetic subtype; suggesting differential MRD kinetics. In addition, we have shown that using a single MRD threshold does not reflect the biological heterogeneity that is a fundamental feature of the disease. Finally, we demonstrate that integrating clinical risk factors as continuous variables with genetics can better define prognostic subgroups. [Display omitted] [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.