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Introduction Measurable residual disease (MRD) is an established component of acute lymphoblastic leukemia (ALL) management in both children and adults. Society guidelines and expert consensus documents include assessment of MRD as the standard of care following induction therapy, consolidation therapy, and at additional time points, depending on the treatment regimen administered.1–3 Further, the approval of blinatumomab for MRD+ B-ALL has advanced the concept of MRD response as a clinical endpoint in ALL. Although the utility of MRD in ALL has been well defined over the last decades, several questions remain. This extended abstract and the associated presentation focus on areas of ongoing controversy and exploration in ALL MRD, including the following.1) Does increasing the depth of MRD assessment add prognostic value? 2) Is there a role for ongoing MRD monitoring once patients achieve MRD– response? 3) Can MRD assessment of the peripheral blood be substituted for bone marrow? 4) Should MRD assays be applied to the analysis of the central nervous system (CNS)?

Several biological and clinical features have been recognized in mantle cell lymphoma (MCL). In recent years, the minimal residual disease (MRD) has been extensively investigated and is now considered as one of the strongest clinical predictors in this lymphoma. This article reviews methods used for the assessment of MRD in MCL and discusses their strengths and weaknesses. In addition, it examines the MRD contribution to the biology knowledge of MCL and the development of effective strategies for its management, including the possibility of personalized treatment based on MRD response.

Measurable residual disease (MRD) is an important biomarker in acute myeloid leukemia (AML) that is used for prognostic, predictive, monitoring, and efficacy-response assessments. The European LeukemiaNet (ELN) MRD Working Party evaluated standardization and harmonization of MRD in an ongoing manner and has updated the 2018 ELN MRD recommendations based on significant developments in the field. New and revised recommendations were established during in-person and online meetings, and a 2-stage Delphi poll was conducted to optimize consensus. All recommendations are graded by levels of evidence and agreement. Major changes include technical specifications for next-generation sequencing-based MRD testing and integrative assessments of MRD irrespective of technology. Other topics include use of MRD as a prognostic and surrogate end point for drug testing; selection of the technique, material, and appropriate time points for MRD assessment; and clinical implications of MRD assessment. In addition to technical recommendations for flow- and molecular-MRD analysis, we provide MRD thresholds and define MRD response, and detail how MRD results should be reported and combined if several techniques are used. MRD assessment in AML is complex and clinically relevant, and standardized approaches to application, interpretation, technical conduct, and reporting are of critical importance.

The decision to incorporate allogeneic hematopoietic stem cell transplant (allo-HSCT) into front-line therapy in adult acute lymphoblastic leukemia (ALL) should be primarily guided by measurable residual disease (MRD) status and the ALL regimen utilized. While there is no doubt that allo-HSCT benefits patients with poor MRD response after induction or consolidation, the indication of allo-HSCT in cases of good MRD clearance is not clear. As targeted immunotherapies result in high MRD-negative CR rates, early incorporation of these therapies may also prove valuable in reducing the need for HCT in the front-line setting. This review discusses the data and controversies related to allo-HSCT in the front-line therapy of Philadelphia chromosome-negative and -positive ALL.

Background: Minimal/measurable residual disease (MRD) post initial therapy is prognostic of long term outcomes in patients (pts) with newly diagnosed MM (NDMM), but has not been used to modify therapy. We hypothesized that the combination of daratumumab, carfilzomib, lenalidomide and dexamethasone (Dara-KRd) would be safe and highly active in pts with NDMM. In addition, we employed MRD by next generation sequencing (NGS) to inform the use and duration of Dara-KRd post-autologous transplant (AHCT) and treatment cessation in pts with confirmed MRD negativity. Methods: Eligible pts had NDMM requiring treatment, CrCl ≥40 ml/min, adequate liver and heart function, ECOG performance status 0-2 with no age limit. There was a planned enrichment for pts with high-risk cytogenetic abnormalities (HRCA). Treatment cycles consisted of daratumumab 16 mg/kg IV days 1,8,15,22 (with typical reduction in frequency with subsequent cycles), carfilzomib 56 mg/m 2 IV days 1,8,15, lenalidomide 25 mg PO days 1-21 and dexamethasone 40 mg PO/IV days 1,8,15,22 repeated every 28 days. Pts received 4 cycles of Dara-KRd as induction, AHCT, and received 0, 4 or 8 cycles of Dara-KRd consolidation, according to MRD status. MRD was evaluated by NGS (ClonoSEQ®) in all pts at end of induction, post-AHCT, and during each 4-cycle block of Dara-KRd consolidation. Primary endpoint was achievement of MRD negativity ( Results: The study accrued 123 participants between 03/2018 and 09/2020. Fifty-three patients (43%) had no HRCA, 46 (37%) had 1 and 24 (20%) had 2+ HRCA [gain 1q, t(4;14), t(14;16), t(14;20) or del(17p)]. Median age was 60 y (36-79) and 20% were 70 or older. Twenty-three percent of pts were non-white, 20% had ECOG 2, 21% had high LDH, and 20% R-ISS3. Disease was trackable by NGS-MRD in 118 (95.9%) of pts. Median follow up is 25.1 mo. Four pts remain on protocol treatment, 20 transitioned to lenalidomide maintenance and 84 (71.2%) have reached confirmed MRD negativity and entered MRD-SURE. For those patients, median follow up post treatment cessation is 14.2 mo. Most common severe adverse events were pneumonia (N=8), and venous thromboembolism (N=3) and 3 patients died during treatment. Overall, 80% of pts have achieved MRD negativity and 66 % MRD < 10 -6. Depth of response improved with each phase of therapy and became similar in patients with 0, 1 or 2+ HR abnormalities as assessed post-AHCT and with MRD-guided consolidation (Figure 1). A similar proportion of patients with 0, 1 and 2+ HRCA reached MRD negativity (78. % vs. 82% vs 79 %) and MRD Conclusion: Monoclonal antibody-based quadruplet therapy, AHCT and MRD response-adapted consolidation therapy leads to the highest rate of MRD negativity reported in NDMM. Near all patients with 0 or 1 HRCA and confirmed MRD negativity remain free of IMWG progression or MRD resurgence despite cessation of treatment. While most patients with ultra-high risk MM reach deep responses with this approach, novel consolidative strategies are needed. For most patients with NDMM, this strategy creates the opportunity of MRD surveillance as an experimental alternative to the burden of indefinite maintenance. Figure 1 Figure 1. Disclosures Costa: Janssen: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Pfizer: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria, Speakers Bureau. Chhabra: GSK: Honoraria. Dholaria: Janssen: Research Funding; Jazz: Speakers Bureau; MEI: Research Funding; Takeda: Research Funding; Pfizer: Research Funding; Angiocrine: Research Funding; Poseida: Research Funding; Celgene: Speakers Bureau. Silbermann: Sanofi Genzyme: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Giri: CareVive: Honoraria, Research Funding; PackHealth: Research Funding. Hari: GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding, Speakers Bureau; Millenium: Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Consultancy; Adaptive Biotech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Oncopeptides: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding, Speakers Bureau; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding, Speakers Bureau; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene-BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding, Speakers Bureau. OffLabel Disclosure: Carfilzomib for newly diagnosed multiple myeloma

Introduction Rituximab (R) administration results in significant outcome improvement in B cell precursor acute lymphoblastic leukemia (B-ALL) patients (pts), but is usually restricted to pts with ≥20% CD20+ leukemic blasts. Yet, this arbitrary cut-off is not proven biologically sensible. Moreover, CD20 expression might differ between blood (pb) and bone marrow (bm) and varies under prednisone during early treatment. In the present GMALL08/2013 trial R is administered to all BCR-ABL1-negative B-ALL pts irrespective of the initial leukemic CD20 expression. We assessed the initial and post-prephase CD20 expression in GMALL08/2013 pts and correlated the values with MRD response after Induction I (Ind I) and Consolidation I (Cons I). A historical B-ALL GMALL07/2003 cohort without R treatment and with available CD20 expression and MRD data was used to evaluate for R-unrelated effects. Methods Comparative immunophenotypic quantification of CD20 expression in 207 B-ALL pts was performed at diagnosis (pb d0 and/or bm d0) and/or (a/o) after a 5-day dexamethasone- and cyclophosphamide-containing prephase (pb d6) under EuroFlow standardized procedures. CD20 median fluorescence intensities (CD20-MFI) and percentages of CD20+ B-ALL blasts/all blasts (%CD20+ BL) were assessed. Minimal residual disease (MRD) was determined after Ind I (after 1x R) and Cons I (after 4x R) by quantitative PCR for clone-specific immune gene rearrangements to stratify pts as molecular complete response (MolCR, MRD negativity, assay sensitivity at least 1x10 -4), molecular intermediate response (MolIR, MRD positive non-quantifiable or positive Results bm d0/pb d0. In 91 paired bm d0/pb d0 samples %CD20+ BL as well as the CD20-MFI were significantly higher in pb in common/pre-B ALL (c/pre-B ALL) (n=76: paired t-test: p pb d0/pb d6. CD20 expression of circulating blasts significantly increased after a 5-day prephase in c/pre-B ALL but not in pro-B ALL in 106 paired pb d0/pb d6 samples (paired t-test of CD20-MFI and %CD20+ BL; n=20 pro-B ALL, p=.09 and p=.25; n=86 c/pre-B ALL, p Molecular response under R. The values of %CD20+ BL were correlated with MRD response after Ind I and Cons I (Fig. 3). Since the CD20 expression in the present cohort was shown to be significantly modulated in a drug- and compartment-dependent manner, we used the highest measured value of %CD20+ BL out of the three available values per patient (bm d0, pb d0 a/o pb d6). In the historical cohort (n=145) one value per patient for %CD20+ BL was available. Due to low CD20 expression pro-B ALL did not show any differences in the %CD20+ BL among the risk groups in the present (Ind I n=23, Cons I n=20) and the historical (Ind I n=11; Cons I n=11) cohort. The differences in %CD20+ BL in relation to molecular response were significant in c/pre-B ALL between MolCR and MolFAIL after Ind I (n=127) and Cons I (n=120) (Mann-Whitney test: p=.0002 and p=.0028) and of lower significance between MolIR and MolFAIL after Ind I (p=.013) and between MolCR and MolIR after Cons I (p=.029) in the present cohort. Within the historical cohort (Ind I n=145, Cons I n=143) no significant differences were observed. Conclusions Leukemic CD20 expression was modulated between compartments (bm d0/pb d0) and showed a significant increase in a drug-dependent manner in c/pre-B ALL (pb d0/pb d6) probably in response to dexamethasone. The results might challenge the conventional eligibility criteria for CD20 targeted treatment in c/pre-B ALL. MRD persisters showed lower initial CD20 expression compared to MRD responders in the present cohort consistently receiving R, but not in the historical cohort without R treatment. Accordingly, R seems to improve the early MRD response predominantly in pts with higher CD20 expression. Supported by DJCLS Figure 1 Figure 1. Disclosures Szczepanowski: Amgen: Speakers Bureau. Trautmann: Amgen: Speakers Bureau. Ritgen: Roche: Consultancy, Other: Travel support, Research Funding; Abbvie: Consultancy, Other: Travel support, Research Funding; Chugai: Consultancy; MSD: Consultancy, Other: Travel support; Celgene: Other: Travel support. Nachtkamp: Celgene: Other: Travel Support; bsh medical: Speakers Bureau; Jazz: Speakers Bureau. Viardot: Kite/Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; University Hospital of Ulm: Current Employment. Baldus: Jazz: Honoraria; Celgene/BMS: Honoraria; Amgen: Honoraria; Novartis: Honoraria. Schwartz: Morphosys: Research Funding; Gilead: Other: Travel grants, Speakers Bureau; Pfizer: Honoraria, Speakers Bureau; Amgen: Membership on an entity's Board of Directors or advisory committees, Other: Travel grants, Speakers Bureau; Novartis: Speakers Bureau; Jazz Pharmaceuticals: Other: Travel grants, Speakers Bureau; BTG International Inc: Membership on an entity's Board of Directors or advisory committees; MSD Sharp & Dohme: Membership on an entity's Board of Directors or advisory committees; Basilea: Other: Travel grants. Goekbuget: Pfizer: Consultancy, Other: Research funding for institution; Amgen: Consultancy, Other: Invited talks for company sponsored symposia (with honoraria); Research funding for institution; Astra Zeneca: Other: Invited talk for company sponsored symposia (with honor); Gilead/Kite: Consultancy; Novartis: Consultancy, Other: Research funding for Institution; Jazz Pharmaceuticals: Other: Research funding for institution; Incyte: Other: Research funding for Institution; Cellestia: Consultancy; Erytech: Consultancy; Morphosys: Consultancy; Servier: Consultancy, Other; Abbvie: Other. Brüggemann: Amgen: Other: Advisory Board, Travel support, Research Funding, Speakers Bureau; Incyte: Other: Advisory Board; Janssen: Speakers Bureau. OffLabel Disclosure: Rituximab administration to patients with CD20-negative (

On behalf of the GRAALL group. Introduction. Tyrosine kinase inhibitors (TKIs) have dramatically improved the outcome of patients diagnosed with Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL). In a previous randomized trial (GRAAPH-2005; Chalandon Y., Blood 2015), our group demonstrated that anthracycline and cyclophosphamide could be safely omitted during the first Hyper-CVAD chemotherapy cycle when combined to imatinib. In the present GRAAPH-2014 trial, we investigated whether the use of nilotinib, a 2 nd generation TKI, would allow further decreasing chemotherapy intensity through the omission of high-dose cytarabine (HD-AraC) during consolidation cycles 2 and 4. Methods. From March 2016, patients aged 18-60 years old were randomized frontline to receive 4 cycles (1=3, 2=4) of chemotherapy combined with continuous nilotinib 400 mg bid. Cycle 1 and 3 were similar in both arms, identical to the less-intensive first cycle of the previous GRAAPH-2005 trial with weekly vincristine and dexamethasone and nilotinib instead of imatinib. Cycle 2 and 4 differed between control arm A (MTX 1 g/sqm over 24h, HD-AraC 3 g/sqm/12h for 2 days) and experimental arm B (MTX 1 g/sqm over 24h only). Marrow minimal residual disease (MRD) was assessed by both BCR-ABL1 and IG-TCR qPCR after each cycle (MRD1-4). Patients in complete remission (CR) after cycle 4 were eligible to receive allogeneic stem cell transplant (alloSCT). Non allografted patients had the option to receive autologous SCT (autoSCT) if a major molecular response (MMolR) (MRD4 BCR-ABL1 40y) and BCR-ABL1 breakpoint region (M/m-bcr). MMolR rate at MRD4 was the primary endpoint of this non-inferiority study, with a margin set at 0.15. In February 2019, the study DSMB decided to stop the randomizations after an unplanned analysis demonstrating a significant excess of relapse in arm B (without HD-AraC). An intention-to-treat analysis is provided. All patients gave informed consent. The study is registered at EudraCT under the number: 2014-002146-44. Results. A total of 156 patients were randomized (77 in arm A, and 79 in arm B). Median age was 47.1 years old (range 18.1-59.9). One-hundred and ten patients had the m-bcr (70.5%) and 46 (29.5%) the M-bcr. An IKZF1 intragenic deletion was found in 87/153 (56.9%). Median follow-up was 2.8 years (95%CI 2.6-3.1). All evaluable patients reached CR after a maximum of two cycles. Three patients died during cycle 1 (2 in arm A, 1 in arm B), and 2 during cycle 2 (1 per arm). Most patients received the 4 scheduled cycles (n=143, 91,7%). AlloSCT was performed in 91 patients (58.3%), whereas 41 patients received an autoSCT (26.3%) with no difference in allo/autoSCT rates between arms. A non-inferiority in late MRD response (MRD4) between the two arms was observed (primary endpoint). MMolR was reached in 55/75 (73.3%) and 61/78 (78.2%) of CR patients in arm A and B, respectively, with an estimated 95% CI of difference of -11% to +16% (-9.2% to +20.8% in the ITT analysis treating missing data as failures). At 3 years, overall survival (OS) was 86.0% in arm A versus 74.2% in arm B (p=.08, Figure A). Progression-free survival (PFS) was 79.6% in arm A versus 57.2% in arm B (p=.008, Figure B). Thirty-one patients experienced hematological relapse (8 in arm A and 23 in arm B). Twenty-height out of 31 relapsed patients were tested for the acquisition of BCR-ABL1 mutations, 20/28 (71%) had at least one mutation and 10/28 (36%) had a T315I mutation. At 3 years, the cumulative incidence of relapse (CIR) was 21.3%, significantly higher in arm B than in arm A (30.8% vs 10.6%, p=.007). When analyzing the CIR considering alloSCT as a competing event for relapse, a significant higher CIR was still observed in arm B as compared to arm A (Figure C). Conclusion. Four cycles of the combined administration of nilotinib and chemotherapy is very efficient for bridging younger adults with Ph-positive ALL to SCT. However, omitting HD-AraC is associated with a higher relapse incidence despite non-inferior levels of BCR-ABL1 MRD4. Figure 1 Figure 1. Disclosures Rousselot: Incyte, Pfizer: Consultancy, Research Funding. Chalandon: Incyte, BMS, Pfizer, Abbie, MSD, Roche, Novartis, Gilead, Amgen, Jazz, Astra Zenec: Other: Travel EXpenses, Accomodation; Incyte: Speakers Bureau; Incyte, BMS, Pfizer, Abbie, MSD, Roche, Novartis, Amgen: Other: Advisory Board. Huguet: Novartis: Other: Advisor; Jazz Pharmaceuticals: Other: Advisor; Celgene: Other: Advisor; BMS: Other: Advisor; Amgen: Other: Advisor; Pfizer: Other: Advisor. Vincent: Takeda: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees. Vey: Amgen: Honoraria; BMS: Honoraria; BIOKINESIS: Consultancy, Research Funding; NOVARTIS: Consultancy, Honoraria, Research Funding; SERVIER: Consultancy; JAZZ PHARMACEUTICALS: Honoraria; JANSSEN: Consultancy. Raffoux: PFIZER: Consultancy; CELGENE/BMS: Consultancy; ASTELLAS: Consultancy; ABBVIE: Consultancy. Boissel: Amgen: Consultancy, Honoraria, Research Funding; CELGENE: Honoraria; Servier: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Incyte: Honoraria; SANOFI: Honoraria; PFIZER: Consultancy, Honoraria; JAZZ Pharma: Honoraria, Research Funding. Dombret: Amgen: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; Jazz Pharmaceuticals: Honoraria, Research Funding; Novartis: Research Funding; Pfizer: Honoraria, Research Funding; Servier: Research Funding; Abbvie: Honoraria; BMS-Celgene: Honoraria; Daiichi Sankyo: Honoraria. OffLabel Disclosure: Nilotinib as a therapy for PH-positive acute lymphoblastic leukemia

Introduction: The open-label, expanded access study (RIALTO) demonstrated that blinatumomab is efficacious with a manageable safety profile in children with relapsed or refractory B-cell precursor acute lymphoblastic leukemia (R/R BCP-ALL). Blinatumomab is a BiTE® (bispecific T-cell engager) immuno-oncology therapy that activates cytotoxic T cells to kill target B cells. Here, findings from the final analysis of RIALTO are presented (NCT02187354). Methods: Enrolled in the study were children >28 days and Results: As of the data cutoff date (January 10, 2020) for the final analysis, demographics and baseline characteristics of 110 patients enrolled (median age, 8.5 years [95% CI 0.4-17.0]), 61% had For best treatment response within the first 2 cycles, results are comparable to that of the primary analysis. Among 110 patients, overall CR rate was 62.7% (n= 69). Of 98 patients with ≥5% blasts at baseline, 59% (n=58) achieved CR; of them, 79% (n=46) achieved an MRD response and 62% (n=39) proceeded to HSCT. The 2 patients with t(17;19) achieved CR with an MRD response. Of the 4 patients with germline trisomy 21 (Down syndrome), 3 achieved CR with an MRD response Among the 12 patients with Of 110 patients treated with blinatumomab, median OS (95% CI) was 14.6 (11-24.5) months with median follow-up time of 18.2 months, which increased by 1.5 months compared with that reported in the primary analysis, with 29.9% of patients still surviving at month 24. Median RFS (95% CI) remains unchanged at 8.5 months (4.7-14.0), with a median follow-up time of 11.5 months in patients who achieved CR; 38% of patients relapsed and 9% died. RFS was more favorable for patients who received HSCT post blinatumomab (70%) than for those who did not (30%) at month 12, respectively, which is consistent with the results from primary analysis. Among patients who had HSCT prior to blinatumomab (n= 45), median OS (95%) was 16.6 (7.1-NE) months vs 14.6 (10.9-24.5) months in patients without HSCT prior to blinatumomab (n= 65). Compared with the primary analysis, 5 additional patients received HSCT after achieving CR in the final analysis. Median OS among patients in CR after HSCT by MRD responders vs MRD non-responders was NE at 15-month analysis (Figure). Safety results in the final analysis were consistent with those reported in the primary analysis. Of 110 patients, 99% experienced TEAEs, with 65% being grade ≥3 (see Table 3 for details). TRAEs were reported in 74% of patients; 26% were grade ≥3 and 19% were deemed serious. Details on grade ≥3 TRAEs are shown in Table 3. The 9 fatal AEs, unrelated to blinatumomab, occurred due to relapse and progressive nature of the disease (Table 3). Conclusions: Overall, the safety and efficacy results from the final analysis are consistent with those reported in the primary analysis as no new safety signals were observed. These findings strengthen the observation that blinatumomab demonstrates durable efficacy and is a suitable treatment option in children with R/R BCP-ALL. Table 1. Disclosures Locatelli: Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Medac: Speakers Bureau; Miltenyi: Speakers Bureau; Bellicum Pharmaceutical: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceeutical: Speakers Bureau; Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Zugmaier:Amgen: Current Employment, Other: Personal Fees ; 20190300609: Patents & Royalties: Licensed patient . Mergen:Amgen: Current Employment, Current equity holder in publicly-traded company. Bader:Medac: Patents & Royalties, Research Funding; Amgen: Consultancy, Speakers Bureau; Neovii: Research Funding; Celgene: Consultancy; Novartis: Consultancy, Speakers Bureau; Riemser: Research Funding. Schlegel:bluebird bio: Honoraria. Bourquin:Servier: Other: Travel Support. Handgretinger:Amgen: Honoraria. Brethon:Amgen: Other: invitation to meetings, remunerations for oral presentations, advices for the record of Blinatumomab in pediatrics in France. Rössig:Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria; Pfizer: Honoraria; Celgene: Membership on an entity's Board of Directors or advisory committees; EUSA Pharma: Membership on an entity's Board of Directors or advisory committees; Genetech: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Kormany:Amgen: Current Employment, Current equity holder in publicly-traded company. Viswagnachar:IQVIA: Current Employment.

Background Refinement of risk-based treatment stratification by minimal residual disease (MRD) at different time points has improved outcomes of childhood acute lymphoblastic leukemia (ALL). In this prospective study we evaluated effects of such stratification, including intensification of therapy based on response assessment at day-15 and MRD at day-29 of induction to test if treatment intensification would improve outcomes. Methods 241 patients, 1–14 years old, newly diagnosed with ALL, were recruited and stratified by risk and MRD response into three treatment Arms (A, B, or C). Arm A was modified from COG AALL0331, B from AALL0232, and C from AALL0232 and AALL0434. Assignments were according to NCI risk, phenotype, rapid vs. slow early response (SER), steroid pretreatment, MLL rearrangement (MLLR), CNS3, and testicular involvement. Patients on Arm A had treatment intensified early based on day-15 marrow results or late based on end-of-induction MRD. Results 5-year OS, EFS, and CIR were 89.5% ± 4.0%, 87.6% ± 4.3%, and 7.1% ± 3.5%. No significant difference was found by B- vs. T cell phenotype. 5-year OS, EFS, and CIR for B-cell ALL were 90.5% ± 2.4%, 88.7% ± 2.6%, and 6.4% ± 2.0%. Outcomes for patients with t(1;19)/TCF3-PBX1 and MLLR were significantly (p ≤ 0.05) worse than for other patients. MRD level at end-of-induction associated with outcomes, but association with a specific MRD value at end-of-induction varied significantly by NCI-risk group. Late treatment intensification based on end-of-induction MRD significantly improved survival outcomes for NCI-SR patients, however, patients with NCI-HR and positive MRD at end-of-induction had significantly inferior outcomes despite intensification. MRD transitions between day-15 and day-29 of induction associated with differences for OS and EFS. Conclusions Arm switching to a more intensive protocol had mixed results. Assigning patients by end-of-induction MRD-risk alone did not reflect response kinetics of the different NCI-risk groups. Although late treatment intensification improved outcomes of NCI-SR patients with positive MRD at end-of-induction, further refinement is needed to improve outcomes of NCI-HR with SER. Integration of NCI-risk group with specific MRD value and time point allows more refined treatment stratification. Trial Registration Protocols were approved by King Abdullah International Medical Research Center and Ethics Review Committee RC08053J

SUMMARY While adult acute lymphoblastic leukemia (ALL) is curable in 40–50% of the patients, the individual prognosis is rather unpredictable due to associated biological and clinical risk factors. In both B- and T-precursor ALL, minimal residual disease (MRD) represents the most sensitive prognostic marker, useful to support critical treatment decisions, ranging from allogeneic stem cell transplantation in patients with inadequate MRD response to chemotherapy only in MRD responsive ones. This optimized risk-adapted strategy allows to spare transplant-associated morbidity and mortality in patients curable by chemotherapy. Further progress is expected from the integration of the MRD-based strategy with improved pediatric-type regimens and novel targeting agents for discrete ALL subsets. These changes are increasing the cure rate to above 50%.

Introduction: Although induction chemotherapy results in a complete remission (CR) in ~70% of newly diagnosed AML patients, post-remission therapies are needed to eliminate minimal residual disease (MRD) and prevent relapse. Consolidation chemotherapy, either as definitive therapy or bridge to bone marrow transplantation (BMT), is currently the most common form of post-remission therapy. Yet, our understanding of its impact on MRD remains limited. In this study, we investigated the effects of consolidation chemotherapy on molecular MRD (mMRD) burden using ultra-deep next generation sequencing (NGS) and correlated treatment response with disease characteristics and survival outcomes in AML patients. Patients and Methods: 91 newly diagnosed AML patients who achieved CR following standard induction chemotherapy were evaluated. Targeted conventional NGS using a 54-gene panel was performed on whole blood (PB) or bone marrow samples collected at diagnosis. PB samples were collected during remission at two consecutive time points (T1 and T2), before and after 1 (n=79) or 2 (n=12) cycles of consolidation chemotherapy, for each patient. To detect mMRD, we used a custom 37-gene hybrid-capture panel and error-corrected NGS based on the duplex sequencing approach with a variant allele frequency (VAF) detection limit of ~1x10-4. For 10 patients, we also performed duplex sequencing analysis on their relapsed samples. Results: NGS of the diagnostic samples identified a total of 298 putative oncogenic mutations in 92% (n=84) of the 91 patients. Ninety percent of these mutations (n=267) were trackable by the custom hybrid-capture panel. Duplex sequencing detected persistence of 56% (n=149) of the trackable mutations in T1 samples; 34% (n=50) of which were clonal hematopoiesis-associated DTA mutations (those involving DNMT3A, TET2, or ASXL1), and the remaining 66% (n=99) were non-DTA mutations. Analysis of T2 samples showed that consolidation chemotherapy reduced the VAF of non-DTA mutations by a median of 73% and cleared 27% (n=27) of them at T2. In contrast, the burden of DTA mutations increased by 0.5% (P < 0.0001 by Mann-Whitney test), and only 2% (n=1) of the mutations was cleared (P = 0.0001 by Fisher's exact test). These findings are consistent with prior studies demonstrating that non-DTA mutations are more reliable markers of leukemic burden than DTA mutations. To study the impact of consolidation chemotherapy at the level of individual patients, the mean VAF of all persistent non-DTA mutations was calculated for each sample and used as a composite measure of mMRD burden (henceforth referred to as "cmMRD"). Analysis of the 10 patients with relapsed samples showed that cmMRD levels tracked well with achievement of remission and disease progression (Fig. 1). In the subset of patients with persistent non-DTA mutations at T1 (n=61), consolidation chemotherapy decreased cmMRD levels by a median of 36% at T2. However, we observed high interpatient variability (Fig. 2); 36% (n=22) of the patients experienced an increase in cmMRD burden after consolidation chemotherapy, and 36% (n=22) had less than a 1 log reduction. Only 28% (n=17) of the patients achieved a log reduction of greater than 1. The likelihood and magnitude of cmMRD response were significantly associated with cytogenetic risk (P = 0.026 by 3x3 Chi-square test; Fig. 3). The proportion of patients with favorable, intermediate, and poor-risk cytogenetics who experienced cmMRD expansion was 17%, 27%, and 71%, respectively. Consistent with these findings, a suboptimal response (defined as cmMRD ratio [T2/T1] > 0.4) was associated with inferior overall survival (HR = 3.29, P = 0.007 by log-rank test; Fig. 4). Conclusions: Our analysis showed that mMRD response to consolidation chemotherapy was highly variable among patients. Although consolidation chemotherapy was effective in deepening the remission for a subset of patients, it failed to lower MRD levels for a substantial proportion of patients, especially those with poor risk cytogenetics. These findings challenge the practice of using consolidation chemotherapy to achieve a deeper remission prior to BMT for high-risk patients and indicate that the opposite outcome may occur instead. NGS-based monitoring of mMRD can potentially be used to distinguish between patients who can remain on consolidation chemotherapy as definitive therapy and those who require a switch in post-remission therapy. Disclosures Gupta: Sierra Oncology: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Honoraria, Research Funding. Maze:Pfizer Inc: Consultancy; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. McNamara:Novartis Pharmaceutical Canada Inc.: Consultancy. Minden:Trillium Therapetuics: Other: licensing agreement. Schimmer:Medivir Pharmaceuticals: Research Funding; Jazz Pharmaceuticals: Consultancy; Novartis Pharmaceuticals: Consultancy; Otsuka Pharmaceuticals: Consultancy. Schuh:Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Jazz: Honoraria, Membership on an entity's Board of Directors or advisory committees; Agios: Honoraria; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees; Teva Canada Innovation: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Yee:Novartis, Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas, Celgene, Otsuka, Shire, Takeda: Membership on an entity's Board of Directors or advisory committees; Agensys, Astex, Hoffman La Roche, MedImmune, Merck, Millenium, Roche/Genentech: Research Funding. Bratman:SVB: Other: is co-inventor of a patent relating to circulating tumor DNA detection technology, which has been licensed to Roche Molecular Diagnostics.. Chan:Agios: Honoraria; AbbVie Pharmaceuticals: Research Funding; Celgene: Honoraria, Research Funding.

In this study, one type of magnetorheological fluid dampers (MRD) used in tracked vehicle is chosen as a research object. Firstly, the dynamic response process is analyzed and the dynamic response time of MRDs is defined. In this study, we consider that the dynamic response time of MRDs includes four components, i.e. the electrical power response time, the electromagnetic response time, the response time of magnetorheological fluid (MRF) and the structure response time. The electrical power response time is tested and the electromagnetic response process and the electromagnetic response time of the MRD are analyzed through the method 3D magnetic finite element analysis. Lastly, the response time of the MRD used in tracked vehicle in various working conditions is tested by MRD response time testing system. With the comparison between testing data and analysis of the electromagnetic response process, we can conclude that the structure response time and the electromagnetic response time occupy the largest proportions of the dynamic response time of the MRD and the feasible methods to shorten the response time is to increase rigidity of the MRD system and reduce the eddy effect.

Background: Ibrutinib inhibits CLL cell proliferation and results in prolonged remission, but MRD responses are rare. Obinutuzumab is a second generation anti-CD20 monoclonal antibody that is effective in CLL and can result in MRD responses. In the IcICLLe study (ISRCTN12695354), 40 participants with CLL requiring treatment (20 treatment-naïve, 20 with relapsed/refractory [R/R] disease) received ibrutinib until complete remission with Aim: to determine the MRD response rates for patients with R/R CLL treated with ibrutinib and obinutuzumab in ibrutinib-naïve trial participants compared to those treated with >1 year prior ibrutinib. Patients: The IcICLLe Extension Study recruited 40 participants with relapsed/refractory CLL requiring treatment. They received continuous ibrutinib (420mg OD) with 6 cycles of obinutuzumab given over 6 months (M). Ten participants had >1 year of prior ibrutinib monotherapy in IcICLLe and 30 were ibrutinib-naïve with obinutuzumab started 24 hours after first ibrutinib dose. Patient characteristics and Adverse Events (AEs, collected from registration until 30 days after treatment cessation and reported at 1, 3, and 6M, and 6-monthly thereafter using the Common Terminology Criteria for Adverse Events v4.0) are shown in Table 1. MRD assessment was performed according to ERIC guidelines with a maximum detection limit of 0.001%/10-5. Results: In the 20 R/R patients treated with ibrutinib monotherapy there were no IWCLL CR/CRi responses and no patients achieved 1 year prior to combination with obinutuzumab (see Table 1). Patients receiving obinutuzumab after >1 year prior ibrutinib monotherapy achieved a higher response rate compared to ibrutinib-naive patients (IWCLL CR/CRi 50% vs. 30%), with a higher proportion of patients achieving PB MRD levels continued to improve in ibrutinib-naïve patients after cessation of obinutuzumab with 30% (9/30 with 4/30 inevaluable) achieving PB MRD 1 year prior to starting obinutuzumab. The difference in extent of disease depletion observed with obinutuzumab may be related to the pre-obinutuzumab disease bulk because the majority of patients (7/10) with >1 year prior ibrutinib treatment had already resolved any lymphadenopathy prior to receiving obinutuzumab. Conclusions: The results suggest that the addition of obinutuzumab to ibrutinib may result in a substantial improvement in the depletion of CLL cells from the PB and BM for ibrutinib-naïve patients. However, a greater impact in MRD response rate and depth of depletion was seen when obinutuzumab was introduced after >1 year of ibrutinib treatment and tumour bulk was low. For patients with persistent disease during/ following pathway inhibition treatments, the addition of anti-CD20 antibody therapy may be effective at improving MRD response rates. Disclosures Rawstron: Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding; BD Bio-sciences: Research Funding; Beckman Coulter: Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Consultancy, Research Funding; Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding. Munir:MorphoSys: Membership on an entity's Board of Directors or advisory committees; Alexion: Honoraria; Novartis: Honoraria; Gilead: Honoraria; Janssen: Honoraria; Abbvie: Honoraria. Brock:GlaxoSmithKline: Equity Ownership; AstraZeneca: Equity Ownership; Merck Sharp Dohme: Other: Reimbursement of conference fees; Roche: Other: Reimbursement of expenses; Lilly: Honoraria. Pettitt:AstraZeneca: Research Funding; Celgene: Research Funding; Chugai: Research Funding; Roche: Research Funding; GSK/Novartis: Research Funding; Gilead: Research Funding; Napp: Research Funding. Fox:Celgene: Consultancy, Other: Travel support, Speakers Bureau; Janssen: Consultancy, Other: Personal fees and non-financial support, Speakers Bureau; Gilead: Consultancy, Other: Travel support, Research Funding, Speakers Bureau; AbbVie: Consultancy, Other: Travel support, Research Funding, Speakers Bureau; Roche: Consultancy, Other: Travel support, Research Funding, Speakers Bureau; Sunesis: Consultancy. Devereux:Janssen: Other: Personal fees; Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Fegan:Janssen: Honoraria; Gilead Sciences, Inc.: Honoraria; Abbvie: Honoraria; Roche: Honoraria; Napp: Honoraria. Bloor:Janssen: Research Funding; AbbVie: Research Funding. Hillmen:Alexion Pharmaceuticals, Inc: Consultancy, Honoraria; Acerta: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding; Novartis: Research Funding; F. Hoffmann-La Roche Ltd: Research Funding; Gilead Sciences, Inc.: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Objective To evaluate the prognostic power of minimal residual disease (MRD) monitored by polymerase chain reaction at defined time points during early treatment in adult patients with acute lymphoblastic leukemia (ALL). Methods Seventy-one patients were treated according to the GMALL 07/2003 protocol and evaluated for MRD in bone marrow by specific clonal rearrangements of Ig/TCR in BCR-ABL negative ALL or fusion gene transcript in BCR-ABL positive ALL. Results Three-year overall survival (OS) was 94% in patients with BCR-ABL negative ALL reaching complete molecular response (CMR) after the first course of chemotherapy (vs. 32% if MRD >10(-4); P=0.001). Patients with CMR prior to the start of consolidation chemotherapy at week 11 had 3-yr OS 82% (vs. 18% if MRD >10(-4); P=0.001). Patients with BCR-ABL positive ALL showed slower MRD dynamics. There was a trend to better OS in patients with 4 log reduction of BCR-ABL transcript prior to HSCT (92% vs. 50%; P=0.065). None of the patients with detectable MRD (both BCR-ABL positive and negative) after HSCT survived 3yr. Conclusion Early MRD kinetics is an important tool for new prognostication models with direct clinical impact irrespective of standard prognostic factors in patients with BCR-ABL negative ALL.

The prognostic value of MRD in large series of childhood T-ALL has not yet been established. Trial AIEOP-BFM-ALL 2000 introduced standardized quantitative assessment of MRD for stratification, based on immunoglobulin and TCR gene rearrangements as polymerase chain reaction targets: Patients were considered MRD standard risk (MRD-SR) if MRD was negative at day 33 (time point 1 [TP1]) and day 78 (TP2), analyzed by at least 2 sensitive markers; MRD intermediate risk (MRD-IR) if positive either at day 33 or 78 and < 10−3 at day 78; and MRD high risk (MRD-HR) if ≥ 10−3 at day 78. A total of 464 patients with T-ALL were stratified by MRD: 16% of them were MRD-SR, 63% MRD-IR, and 21% MRD-HR. Their 7-year event-free-survival (SE) was 91.1% (3.5%), 80.6% (2.3%), and 49.8% (5.1%) (P < .001), respectively. Negativity of MRD at TP1 was the most favorable prognostic factor. An excellent outcome was also obtained in 32% of patients turning MRD negative only at TP2, indicating that early (TP1) MRD levels were irrelevant if MRD at TP2 was negative (48% of all patients). MRD ≥ 10−3 at TP2 constitutes the most important predictive factor for relapse in childhood T-ALL. The study is registered at http://www.clinicaltrials.gov; “Combination Chemotherapy Based on Risk of Relapse in Treating Young Patients With Acute Lymphoblastic Leukemia,” protocol identification #NCT00430118 for BFM and #NCT00613457 for AIEOP.

Assessment of minimal residual disease (MRD) has acquired a prominent position in European treatment protocols for patients with acute lymphoblastic leukemia (ALL), on the basis of its high prognostic value for predicting outcome and the possibilities for implementation of MRD diagnostics in treatment stratification. Therefore, there is an increasing need for standardization of methodologies and harmonization of terminology. For this purpose, a panel of representatives of all major European study groups on childhood and adult ALL and of international experts on PCR- and flow cytometry-based MRD assessment was built in the context of the Second International Symposium on MRD assessment in Kiel, Germany, 18-20 September 2008. The panel summarized the current state of MRD diagnostics in ALL and developed recommendations on the minimal technical requirements that should be fulfilled before implementation of MRD diagnostics into clinical trials. Finally, a common terminology for a standard description of MRD response and monitoring was established defining the terms 'complete MRD response', 'MRD persistence' and 'MRD reappearance'. The proposed MRD terminology may allow a refined and standardized assessment of response to treatment in adult and childhood ALL, and provides a sound basis for the comparison of MRD results between different treatment protocols.

Slow early response indicates poor prognosis in childhood ALL. We aimed to evaluate if post-induction MRD levels had different prognostic impact in precursor B-cell (pB) or T-cell ALL. From 07/2000 to 06/2006, 4730 pts with ALL were enrolled in trial AIEOP-BFM ALL 2000. MRD levels were centrally measured by real-time quantitative polymerase chain reaction using the identification of clone-specific T-cell receptor and immunoglobulin gene rearrangements. MRD study time-points (TP) were treatment day 33 (TP1, end of induction) and day 78 (TP2, after consolidation). To define MRD negativity, two markers with a sensitivity of at least 10−4 were required. Patients were treated with BFM induction (protocol I-A), consolidation (I-B), extra-compartment/intensified consolidation (HD-MTX in non-high-risk patients, pulses in high-risk patients), reinduction, and maintenance. MRD analysis at one or two time points suceeded in 3707 pts; the immunophenotype was available from 3636 pts. MRD levels and corresponding estimated 5-year event-free survival (5y-pEFS) comparing pB- and T-ALL are shown in Table 1 (3yrs median follow-up). MRD response in T-ALL was slower than in pB-ALL resulting in a higher percentage of pts with high MRD load in T-ALL. In pB-ALL as well as T-ALL, high MRD levels at TP2 were well predictive to identify pts with poor prognosis. For prediction of good prognostic subgroups, TP1 was more appropriate identifying a subgroup with excellent 5y-pEFS of >90% in case of MRD negativity. Specificity of TP1 was poor in T-ALL if the pB-ALL criteria of MRD negativity were applied. If MRD low positive and MRD negative T-ALL pts were combined, the discrimination was as good as in pB-ALL. The optimal choice of MRD evaluation time points depends on biological factors and treatment, and is most relevant for MRD-based risk stratification. Table 1 . pB-ALL T-ALL n % 5y-pEFS % (SE) n % 5y-pEFS % (SE) all 3177 100% 82.3 (1.0) 459 100% 77.2 (2.2) MRD TP1 neg 1399 44.1 92.5 (1.0) 75 16.4 94.3 (2.8) 10E-4/−5 1122 35.4 81.9 (1.7) 116 25.4 91.2 (2.8) 10E-3 393 12.4 66.4 (3.5) 110 24.1 75.3 (4.6) ≥10E-2 256 8.1 53.2 (4.3) 156 34.1 59.8 (4.5) MRD TP2 neg 2464 77.6 87.7 (1.0) 220 47.9 91.9 (2.0) 10E-4/−5 523 16.5 68.9 (2.9) 143 31.2 76.6 (3.9) 10E-3 107 3.4 56.3 (6.5) 58 12.6 50.2 (8.1) ≥10E-2 82 2.6 38.0 (7.3) 38 8.3 33.2 (8.3)