Complete Minimal Residual Disease Research Articles

Clinical efficacy and safety of flumatinib versus dasatinib combined with multi-drug chemotherapy in adults with Philadelphia-positive acute lymphoblastic leukemia

Introduction: Flumatinib, a highly selective ABL kinase inhibitor, exhibits stronger inhibition of intracellular BCR-ABL tyrosine kinase activity, compared to Imatinib. However, there is limited research comparing the real-world efficacy and safety of flumatinib and dasatinib in patients with Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL). Objective: Investigating the differences in therapeutic efficacy and safety between flumatinib and dasatinib in combination with multi-drug chemotherapy for the treatment of newly diagnosed Ph+ ALL. Method: In this study, we assessed 43 patients with newly diagnosed Ph+ ALL (20 in the flumatinib group, 23 in the dasatinib group). Results: There were no significant differences in gender, age, fusion gene type, initial blood routine, bone marrow blast cell ratio or chromosome karyotype between the two groups. Within 1 month, there were no significant differences in the complete response (CR), major molecular response (MMR) or minimal residual disease (MRD) negativity rate between the flumatinib and dasatinib groups. Similarly, within 3 months, there were no significant differences in CR or MMR rates between the two groups. However, the rates of complete molecular response (CMR) and MRD negativity within 3 months were significantly higher in the flumatinib group, compared to the dasatinib group (P < 0.05). Additionally, the flumatinib group exhibited fewer adverse reactions compared to the dasatinib group. Conclusion: These findings suggest that flumatinib is a safe and effective tyrosine kinase inhibitor (TKI) for achieving CMR and MRD negativity in patients with Ph+ ALL, as supported by this small series of patients.

A Modified Busulfan/Cyclophosphamide Preconditioning Regimen Incorporating Selinexor for Allogeneic Hematopoietic Stem Cell Transplantation in Relapsed/Refractory Hematologic Malignancies

Objective: To investigate the safety and efficacy of a modified busulfan (Bu)/cyclophosphamide (Cy) conditioning regimen incorporating Selinexor for allogeneic hematopoietic stem cell transplantation in relapsed/refractory hematologic malignancies. Methods: We retrospectively evaluated the clinical outcomes of patients with hematologic malignancies who had received allo-HSCT with conditioning incorporating Selinexor at the Institute of Hematology and Blood Disease Hospital. Results: Between September 2022 and June 2023, 13 adult patients with high-risk hematologic malignancies were enrolled including 6 males and 7 females with a median age of 49 (13-58) years. There were 7 patients with acute myeloid leukemia (AML), 4 with myelodysplastic syndromes (MDS)/AML, 1 with multiple myeloma (MM) and 1 with extramedullary plasmacytoma. Six patients were in complete remission (CR), four in CR1, two in ≥CR2, five in non-remission (NR), and two patients were in a progressive disease status (PD) prior to conditioning. Three patients received matched-sibling donors transplant, while ten received related haploid hematopoietic stem cell transplantation. All patients had received myeloablative conditioning regimen incorporating Selinexor. Eleven patients received the conditioning: Bu (3.2mg/kg/d*2d); Melphalan (Mel, 60mg/m 2/d*2d), Fludarabine(Flu 30mg/m 2/d*3d) or CLA (5mg/m 2/d*3d), Cy (40mg/kg/d*2d), Selinexor 60mg/d*2d. The other 2 patients received the conditioning: Decitabine (DAC, 20mg/m 2/d*5d), Bu (3.2mg/kg/d*3d), Cy (40mg/kg/d *2d), Flu 30mg/m2/d*3d, Selinexor 60mg/d*2d. The median amount of infused mononuclear cell and CD34 + stem cell were 11.72×10 8/kg(range, 9.66 to 14) and 2.92×10 6/kg(range, 2.35 to 9.61), respectively. All the 13 patients achieved neutrophil engraftment with a median time of 12 (range, 9 to 18) days and 9 patients achieved platelet engraftment with a median time of 13 (range, 11 to 30) days. Four patients were still experiencing prolonged isolated thrombocytopenia. All patients achieved complete donor chimerism and minimal residual disease (MRD) negative at 30 days post-transplantation.The cumulative incidence of cytomegalovirus (CMV) reactivation was 15.4%, while Epstein-Barr virus (EBV) reactivation was not observed. Six patients (46.2%) experienced mucosal barrier injury, comprising three cases of oral mucosal ulcer, one case of digestive tract hemorrhage, and two cases of hemorrhagic cystitis. The cumulative incidence of II-IV and III-IV acute GVHD was 23.1% and 15.4%. The median follow-up for all the participants was 93 (40-316) days after transplantation. Only one patient was dead due to Thrombotic Microangiopathy (TMA) 78 days after transplant. One patient experienced molecular relapse 156 days after transplant, and another patient experienced hematology relapse 20 days after transplant. The two relapsed patients had received donor lymphocyte infusions after chemotherapy. The other 10 patients were still in CR with complete donor chimerism and MRD negative. The cumulative transplant-related mortality (TRM) and relapse rates are 7.7% (1 case) and 15.4% (2 cases), respectively. Conclusions: Incorporating Selinexor into the modified BU/CY conditioning regimen for allogeneic HSCT in patients with relapsed/refractory hematologic malignancies demonstrated a favorable safety profile. Ongoing prospective trials will provide valuable insights into the potential benefits of Selinexor in patients undergoing HSCT.

Early-Stage Follicular Lymphoma: Learnings from the Final Analysis of the Multicenter Phase II FIL (Fondazione Italiana Linfomi) “Miro” Trial, Combining Local Radiotherapy and MRD-Driven Immunotherapy

Introduction. Early-stage follicular lymphoma (FL) is usually managed with involved field radiotherapy (IFRT), allowing a complete and long-lasting eradication of the disease in 40-50% of patients (pts). The aim of this multicenter phase II prospective study was to evaluate if a minimal residual disease (MRD)-driven immunotherapy consolidation after IFRT can improve the outcome of pts unlikely to be cured by IFRT only, and to assess the therapeutic effect of IFRT and anti-CD20 consolidation by MRD evaluation. Methods. One hundred and ten pts with stage I/II FL were enrolled; 106 were evaluable and treated with 24 Gy IFRT. Peripheral blood (PB) and bone marrow (BM) samples were centralized to the FIL (Fondazione Italiani Linfomi) MRD Network of EuroMRD-certified laboratories. In pts BCL2::IGH+ at baseline by both nested PCR (NEST) and RQ-PCR (RQ) in the BM and/or (a/o) PB, MRD was analyzed after IFRT and every 6 months over a 3-year period. Pts who were MRD+ by both NEST and RQ in the BM a/o PB after IFRT or who became MRD+ during the follow-up were treated with 8 weekly doses of the anti-CD20 monoclonal antibody ofatumumab (OFA). The primary objective of the study was to define the efficacy of immunotherapy in obtaining a negative MRD. Results. Of the 106 evaluable pts, 50 were males (47%). Median age was 55.5 years (29-83). The FLIPI score was 0 in 60% of pts, 1 in 34%, 2 in 6%; 69% of pts had inguinal site involvement, significantly more frequent in young patients. At baseline, 30.5% of pts had a BCL2::IGH rearrangement (30 MBR, 1 MBR and mcr, 1 mcr) in the BM a/o PB; the concordance between compartments was 87%. BCL2::IGH+ and BCL2::IGH- pts were not significantly different, except for a younger age (p 0.009) and a more frequent FLIPI 0 (p 0.052) among marker negative cases. All but 1 pt achieved a clinical response after IFRT; 1 pt died soon after IFRT of unrelated causes. MRD evaluation after IFRT revealed the persistence of BCL2::IGH+ cells in the PB a/o BM in 60% of pts. MRD+ pts, either after IFRT (n=18) or in case of conversion to MRD+ during the follow-up (n=8), received OFA, obtaining a conversion to MRD- in 23/25 evaluable pts (92%, CI 74-99%), significantly superior to the expected 50%. After a median follow-up of 46.3 months (m) (range 11-66), of the 23 pts who achieved a MRD- with OFA, 5 returned MRD+ (4 underwent OFA re-treatment, achieving a second MRD-, 1 relapsed as a transformation), 4 relapsed being MRD-, 14 remain in complete remission and MRD-, with a duration of molecular response at the last molecular assessment of 30 months (range 6-36). Overall, a clinical relapse was observed in 29 pts submitted to IFRT and 1 patient progressed soon after IFRT. A confirmed histologic transformation to DLBCL was observed in 5 of these patients. Among the 73 “marker negative” patients, 20 relapsed (27.4%) over time, whilst among the 32 BCL2::IGH+ at baseline 9 (28.1%) were resistant or relapsed (p=0.939). The administration of OFA was associated to a significantly reduced risk of POD24 (p= 0.035). Overall, the 24-m and 36-m overall survival (OS) were 100% and 98.9%, respectively; the 24-m and 36-m PFS were 83.7% and 77.4%, respectively. PFS was not different according to the presence or absence of BCL2::IGH at enrollment (p=0.820). PFS was significantly different according to the FLIPI score (p=0.041), but not different according to gender (p=0.696), stage I-II (p=0.122), histological grade (p=0.212), inguinal nodal site vs others (p=0.492). The Kaplan Meier landmark analysis, stratified by MRD, at m+6 (p=0.228), m+12 (p=0.003), m+18 (p=0.0002), m+24 (p=0.004) showed that PFS significantly improved from m+12 onwards when a negative MRD was present (Figure 1). Conclusions. IFRT alone is often insufficient to eradicate FL, inducing a MRD- status only in 40% of pts, long-lasting only in a third of them. An immunotherapy consolidation with OFA after IFRT in MRD+ pts was capable of increasing the molecular responses to 92%, allowing to achieve the primary objective of the study, though this effect was not always persistent. The achievement of a molecular remission correlated significantly with a reduction in the incidence of relapse over time, although this strategy was applicable only to 30% BCL2::IGH+ PET/CT staged FL pts. A consolidation strategy with more effective agent should be advisable. With these limits, a clinical advantage of the MRD-driven treatment strategy is suggested, although not largely applicable.

Short-Term Blinatumomab As a Bridge Therapy for Hematopoietic Stem Cell Transplantation in B-Cell Acute Lymphoblastic Leukemia with Low Leukemia Burden

Introduction The influence of pre-transplant leukemic load on relapse and long-term survival is well-documented among patients with B-cell acute lymphoblastic leukemia (B-ALL). Blinatumomab, a bispecific T cell engager, has shown promising results as an effective treatment for relapsed B-ALL. However, the dosage (28μg/day) and duration (28 days of continuous infusion) of blinatumomab have been predominantly determined in a relapsed leukemia context. Therefore, in the minimal residual disease (MRD) scenario, the standard dosing may exceed the required amount, potentially leading to increased toxicity, delays in transitioning to the scheduled transplant, and superfluous economic expenditure. Methods We enrolled B-ALL patients with ≤10% MRD who were slated for allogeneic hematopoietic stem cell transplantation (ASCT). MRD was quantified via multi-parameter flow cytometry or polymerase chain reaction (PCR) for the target gene. Blinatumomab therapy began at 8 μg/day, gradually escalating to 28 μg/day over only 5-10 days. Bone marrow cells were harvested post-blinatumomab therapy. Upon acquiring MRD negativity, patients proceeded to the transplantation protocol. All patients underwent myeloablative conditioning with chidamide, fludarabine, cytarabine, and busulfan. Peripheral stem-cell grafts were harvested from HLA-matched sibling donors (MSD), matched unrelated donors (MUD), or haploidentical donors (HID). Post-transplantation acute GVHD prophylaxis consisted of cyclophosphamide and cyclosporine. For HID transplant recipients, mycophenolate mofetil was added from day +5 to day +35. Follow-up examinations were scheduled at +1, +2, +3, +4, +6, +9, +12, +18, and +24 months post-transplant. Results Our study cohort comprised 20 patients (13 females, 7 males), median age 35.5 years (range 15-58). Patient and disease characteristics are summarized in Table 1. During the blinatumomab therapy, 8 patients (40%) experienced grade 1 cytokine release syndrome (CRS), and 1 patient (5%) experienced grade 2 CRS, with no instances of grade 3 or higher CRS observed. All patients achieved complete remission (CR) and MRD clearance evaluated by flow cytometry following blinatumomab treatment. Eleven patients were diagnosed with Philadelphia chromosome-positive ALL, and 5 of them didn't achieve MRD clearance evaluated by PCR. Allo-SCT was conducted following blinatumomab at a median interval of 5.5 days (range 1-29) using MSD in 4 patients, MUD in 2 patients, and HID in 14 patients. The median time to neutrophil and platelet engraftment was 12 days (range 9-17) and 13 days (range 9-28), respectively. The median follow-up duration was 10.2 months (range 2-21.7). By day +30 post-ASCT, all patients achieved CR and MRD clearance with full donor chimerism. Acute GVHD (aGVHD) (grades II-IV) and (grades III-IV) incidences were recorded at 10.0% and 5.3% respectively (Figure 1A). One fatality occurred due to COVID-19-associated pulmonary aspergillosis 7.2 months post-transplantation. Among the 18 evaluable patients, the estimated 1-year cumulative incidence of chronic GVHD (cGVHD) was 44.4%, with no instances of severe cGVHD observed (Figure 1B). No patient relapsed at the last follow-up on July 31, 2023. The estimated 1-year progression-free survival (PFS) and overall survival (OS) both stood at 90% (Figure 1C). Conclusion Short-term blinatumomab as a bridging therapy for adult patients with low-burden B-ALL transitioning to ASCT demonstrates comparable efficacy to standard dosing regarding disease control and survival outcomes.

The Impact of Inotuzumab Ozogamicin (InO) Treatment on Brexucabtagene Autoleucel (Brexu-cel) Outcomes in Adults with Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia (B-ALL)

Cellular Immunotherapies: Late Phase and Commercially Available Therapies The Impact of Inotuzumab Ozogamicin (InO) Treatment on Brexucabtagene Autoleucel (Brexu-cel) Outcomes in Adults with Relapsed/Refractory B-cell Acute Lymphoblastic Leukemia (B-ALL) Introduction: Brexu-cel is the first approved CD19-directed chimeric antigen receptor (CAR) T-cell therapy for adult patients (pts) with relapsed/refractory (r/r) B-ALL. InO, an anti-CD22 antibody drug conjugate, is also approved for the same indication. With the accessibility to several targeted therapies in r/r B-ALL, the optimal sequence remains uncertain. The effect of prior treatment with InO on brexu-cel outcomes remains underreported, especially as a bridging therapy, as well as the effect of previous response to InO on post brexu-cel outcomes. Methods: This is a retrospective multicenter analysis from 25 U.S. institutions of adults (≥18 years) with r/r B-ALL treated with commercial brexu-cel from 2021 to 2023 post FDA approval. Methodologies for assessing minimal residual disease (MRD) (minimal threshold of 10 -4) included flow cytometry, NGS, or qPCR depending on institutional practice. Progression-free survival (PFS) and overall survival (OS) were calculated from day of brexu-cel infusion and were not censored for hematopoietic cell transplant (HCT) or maintenance. All living patients were censored at the time of last follow-up prior to data lock, which occurred on June 30, 2023. Results: Among 152 infused, 83 (54.6%) had pre-CAR InO therapy (InO-exposed), with a median of 3 administered doses (range: 1-22). Within the InO-exposed cohort, 23 (28%) pts received InO as a CAR T-cell bridging therapy (ie, between apheresis and lymphodepletion) with or without pre-apheresis and 60 (72%) pts received InO only during pre-apheresis. Baseline characteristics for InO exposed and InO-naïve pts are shown in Table 1. InO-exposed pts had higher median prior lines of therapies (4 vs. 3; p= 0.05), more frequently had active disease (≥5% marrow blasts) at the time of apheresis (67% vs. 44%, p= 0.02), and had lower incidence of Ph+ disease (19% vs. 45%, p=0.003), compared to InO-naïve pts, respectively. The incidences of cytokine release syndrome (CRS) (85% vs. 85%, p= 0.26) and ICANS (58% vs. 57%, p= 0.36) post infusion were similar, and post-infusion death in remission occurred in 17% and 12% among InO-exposed and InO-naïve pts, respectively. Morphological complete remission (CR) and MRD- rates following brexu-cel infusion were 89% and 77% for InO-exposed pts, and 92% and 70% for InO-naive pts, respectively. Post CAR therapy, more InO-naïve pts underwent consolidation/maintenance therapy (transplant, chemotherapy, or TKIs) compared to InO-exposed pts (41% vs. 19%, p= 0.004). The median follow-up after brexu-cel was 8.4 (range) months. Median OS (not reached (NR) vs. 12 months; p= 0.033) and median PFS (NR vs. 7 months; p= 0.029) were superior in InO-naïve pts compared to InO-exposed pts, respectively. However, after adjusting for pre-apheresis disease burden and post-CAR maintenance therapy, there were no longer significant differences in OS (HR= 1.25;95%CI: 0.62-2.53; p= 0.53) or PFS (HR= 1.24;95%CI:0.71-2.16, p=0.45) based on pre-CAR InO exposure. When InO-exposed pts were stratified based on prior InO-response (CR vs. no response), InO-responsive pts had superior estimated 12-month OS (64%) and PFS (38%) relative to InO-refractory pts (OS: 33%; PFS: 34%), but inferior to InO-naïve pts (OS: 75%; PFS 56%), with p-values of 0.0001 and 0.021 for OS and PFS, respectively (Figure 1). The timing of pre-CAR InO therapy did not impact brexu-cel survival outcomes, with comparable estimated 12-month OS (43% vs. 58%, p= 0.35) and PFS (46% vs. 38%, p= 0.57) for InO-exposed pts during bridging therapy and patients who received InO as a therapy prior to apheresis. Conclusion: After adjusting for pre-CAR disease burden and post-CAR consolidation/maintenance, we found that prior InO exposure does not significantly associate with PFS or OS following brexu-cel. However, relative to InO-responsive patients, patients who were InO-refractory appear to have worse post-CAR survival outcomes. Finally, timing of InO administration (ie as a prior line of therapy or as CAR bridging) did not influence outcomes brexu-cel outcomes.

A Real-World Evidence on Effectiveness and Safety of Blinatumomab in Patients with B-Cell Acute Lymphoblastic Leukemia

Introduction Blinatumomab, a bispecific T-cell antibody, has emerged as a novel therapy with a promising efficacy and tolerable safety in patients with B-cell acute lymphoblastic leukemia (B-ALL). However, there is a paucity of data on blinatumomab for patients with newly diagnosed and relapsed/refractory (R/R) B-ALL in frontline and relapsed settings outside the clinical trials. This study aimed to describe the treatment patterns, effectiveness and safety of blinatumomab in Chinese patients with B-ALL. Methods In this retrospective observational study, data of patients with B-ALL who received at least one dose of blinatumomab in frontline or relapsed settings between August 2021 and June 2023 were collected from electronic medical data of the Department of Haematology of the First Affiliated Hospital of Soochow, China. The primary endpoint of the study was the treatment pattern of blinatumomab therapy, including median treatment cycles. Secondary endpoints included complete remission (CR)/CR with incomplete blood cell recovery (CRi) rate, minimal residual disease (MRD) negativity (i.e., complete MRD remission, defined as MRD &amp;lt;0.01%), median event-free survival (EFS) and 1-year EFS rate, median overall survival (OS) and 1-year OS rate, duration of response (DOR) and adverse events (AEs). Results In total, 96 patients with B-ALL (53 males and 43 females) were included. Of these, 53 received frontline treatment (blinatumomab used for first line remission induction: n=6; first line consolidation: n=39; first line induction or consolidation unknown: n=8), and 43 were R/R patients (blinatumomab for remission re-induction: n=28; R/R consolidation: n=14; R/R re-induction or consolidation unknown: n=1). The median age was 34 years (range: 11-67). Among R/R patients, 18 (18.8%), 12 (12.5%) and 13 (13.5%) had received 2, 3, and ≥3 previous lines of treatments, respectively. Sixteen patients were refractory to the last treatment. Among patients using blinatumomab for consolidation, MRD status at the start of therapy was positive in 29 (30.2%), and negative in 23 (24.0%) patients. Most of the patients (66.7%) received 1 cycle of blinatumomab followed by 2 (20.8%), 3 (7.3%), 4 (4.2%), and 5 (1.0%) cycles of the drug. The median treatment cycle was 1 (range: 1-5) with a median follow-up of 205 days (range: 15-652). In frontline treatment, all those using blinatumomab for remission induction and first line unknown status achieved CR with the CR/CRi rate of 100% (14/14) after blinatumomab. In patients with evaluable MRD (n=47) in the frontline setting, 87.2% (n=41) achieved MRD negativity within the 2 cycles of blinatumomab. In the following cycles, 3 more patients achieved MRD remission with overall complete MRD remission rate of 93.6% (44/47). In R/R re-induction patients, the CR/CRi rate was 50% (14/28) after blinatumomab treatment. Complete MRD remission rate in R/R patients who achieved CR within 2 cycles of blinatumomab was 73% (19/26). Median EFS was not reached (NR) in both frontline and R/R patients and the 1-year EFS rate was 90.8% (95% CI: 67% - 97%) and 55.1% (95% CI: 30% - 74%), respectively (Figure 1). Stratification of EFS by CR status at blinatumomab initiation showed 1-year EFS rate of 93.8% and 100% in first line consolidation and remission induction patients, respectively, whereas, R/R consolidation and re-induction patients showed 1-year EFS rate of 66.8% and 59.3%, respectively. None of the frontline treated patients died until the last follow-up time. In R/R patients the median OS was not reached and the 1-year OS rate was 70.9% (95% CI: 50% - 84%). OS stratified by CR status in R/R patients showed 1-year OS of 87.5% in consolidation and 69.9% in re-induction patients. Median DOR was NR in both frontline and relapsed settings. Seven (7.3%), and 3 (3.1%) patients reported any grade, and grade ≥3 cytokine release syndrome, respectively. Immune effector cell-associated neurotoxicity syndrome was reported by 1 patient (grade ≥3). Infection of any grade and grade ≥3 was reported by 6 (6.2%) and 4 (4.2%) patients, respectively. Increase in liver enzymes and neutropenia were observed in 1 patient (grade ≥3) each. Conclusion This study showed that using blinatumomab for remission induction and consolidation with one to five cycles was effective in the treatment of patients with B-ALL in the frontline as well as relapsed settings and had a tolerable safety profile.

High Efficacy and Feasibility of a Full Pediatric Induction in Adults Aged up to 55 Years with Philadelphia-Negative Acute Lymphoblastic Leukemia

Background: Treatment of acute lymphoblastic leukemia (ALL) in adults has historically shown unsatisfactory outcomes when compared to the outstanding results obtained in pediatric patients. Pediatric protocols rely on increased drug intensity and on a tighter evaluation of minimal residual disease (MRD) for early intensification. Nowadays, pediatric-inspired protocols have been established as the standard of care for adolescents and young adult patients (AYA) leading to improved results. In the setting of older patients, probably due to the limited data available, the feasibility of such intensive therapies, and in particular the administration of high doses PEG-asparaginase (PEGASP), is still a matter of debate. In this context, the NOPHO group reported that a full-pediatric protocol was feasible and highly effective in adult patients, up to 45 years of age. Aim: The aim of our study was to evaluate the feasibility and efficacy of the entire full pediatric AIEOP-BFM LAL 2009 protocol in an older cohort of adult patients up to 55 years. Methods: Since May 2013, 28 consecutive adults diagnosed with Ph-neg ALL received first line therapy according to AIEOP- BFM-ALL 2009 protocol, which includes high PEG-asparaginase (PEGASP) doses, with an accurate MRD-driven therapeutic strategy. The protocol consists of 2 induction blocks: IA (Vincristine, Daunorubicin, PEGASP, IT methotrexate) and IB (Cytarabine, 6-mercaptopurine, cyclophosphamide, IT methotrexate), I consolidation block (high-dose methotrexate, 6-mercaptopurine, IT methotrexate), maintenance therapy (6-mercaptopurine, weekly MTX, IT Methotrexate). Median age in our study was 45 years (range 17-55), equal to the maximum age allowed in the NOPHO study. Fifteen patients had B-ALL, 13 T-ALL/T including 5 Early-T phenotype. Dose intensification and stem cell transplantation (SCT) were scheduled according to baseline and MRD-driven risk assessment. MRD was evaluated by multicolor-flow cytometry (MFC), with a threshold for positivity of 0.025%, and molecular PCR for JH rearrangement (MOL), with a sensitivity greater or equal to 10-4 in all patients. Patients with MOL MRD &amp;gt;10-4 but &amp;lt;10-3 were defined as low-level positive. MRD time points were day 33 and day 78 (MFC and MOL). Results: All patients achieved complete hematological remission following the first Induction course (100%). One patient died during induction due to infection by multidrug resistant P. aeruginosa. In general, therapy was well tolerated. Remarkably, patients in this study received high dose of PEGASP (median 10000 UI/sqm, equal to 4 administrations at 2500 UI/sqm each) without experimenting life threatening toxicities, which mostly consisted in asymptomatic elevation of transaminase (7 patients G3, 1 G4) and/or bilirubin (9 patients G3, 1 G4) only requiring supportive therapy. No major bleeding or thrombotic events o other &amp;gt;G2 toxicities were observed. All except one patient achieved CR at day 33 and all patients achieved CR at day 78. MFC MRD evaluation at day 33 resulted negative in 24/25 evaluable patients (95%). Day 33 MOL-MRD was evaluated in 22 patients, and resulted negative, low level positive or positive in 14, 5 and 3 patients, respectively. MRD assessment at day 78 showed both MFC and MOL negativity achieved in all 25 and 22 evaluated patients, respectively (Fig. 1). Four very high-risk patients underwent SCT in negative MRD status. After a median follow-up of 59 months (CI 95% 38.45-78.63), median survival was not reached, 5-years OS was 88.7% (Fig. 2). One patient died due to progressive transverse myelitis after isolated CNS relapse and one patient died due to sudden cardiac arrest while in complete MRD negative remission, 6 months after completion of therapy. All other 25 patients are alive and in complete MRD negative remission. Conclusion: The application of a full pediatric induction regimen in a cohort of adult ALL patients with a median age of 45 years proved to be feasible, with tolerable toxicities. In particular, we didn't observe major toxicities during the intensified PEGASP administration and all patients were able to receive the planned PEGASP doses. The possibility to maintain the correct timing translated in a very high MRD negativity rate and promising OS survival.

The Value of PET/CT Combined with Next-Generation Flowcytometry in Minimal Residual Disease Detection and Prognostic Evaluation of Multiple Myeloma

Background: Minimal residual disease (MRD) plays an increasingly vital role in efficacy evaluation of multiple myeloma (MM), especially in the era of novel drugs. Currently, the mainstream MRD evaluation methods include next-generation sequencing (NGS), next-generation flowcytometry (NGF) and positron emission tomography/computed tomography (PET/CT). However, it remains to be solved which method holds the best sensitivity and specificity. Our research intends to compare the sensitivity between 11C-acatate, a novel PET tracer with the traditional one 18F-FDG, and meanwhile, explore the prognostic value of PET/CT and NGF. Methods: Our research included MM patients treated in our center between 2015.11 to 2021.11, who received standard medication and reached at least partial response. The patients were examined by 11C-acatate PET/CT (AC-PET), 18F-FDG PET/CT (FDG-PET) as well as Euroflow MRD assessment. Baseline characteristics including ISS stage, cytogenetic abnormalities, treatment and response were collected. Statistical analysis was conducted using SPSS 24.0, with Χ2 test or McNemar test for Categorical variables, and Kaplan-Meier analysis or COX regression model for survival analysis. Results: A total of 54 patients were included, with 42 patients received dual-tracer PET/CT, 10 patients received FDG-PET only and 2 patients received AC-PET only. 37 patients also underwent NGF MRD evaluation. The average age of all patients were 58.5 years, with ISS III patients accounting for 53.7% and cytogenetically high-risk patients accounting for 60.4%. 46.3% of patients completed autologous stem cell transplantation, and 90.7% of patients reached at least very good partial response. A total of 11 patients found minimal residual disease by PET/CT, with a sensitivity of 18.2% by AC-PET and 7.7% by FDG-PET. Although it appeared that AC-PET had superior sensitivity compared with FDG-PET, the difference was statistically insignificant (p=0.14). The paired test of dual-tracer PET/CT scan revealed a same result (p=0.13). In patients conducted NGF, the MRD positive rate was 40.5%. Paired test between NGF and PET/CT in these patients demonstrated that sensitivity of NGF was significantly higher than PET/CT (p=0.01). In terms of progression-free survival (PFS), single-factor analysis showed that ISS stage II or III, response not reaching stringent complete response and positive MRD by NGF were all adverse prognostic factor, with p value of 0.019, ＜0.001 and 0.008, respectively. Cox regression analysis further determined that positive MRD by PET/CT was also an independent prognostic factor. Conclusion: The novel tracer AC-PET is advantageous over traditional FDG-PET in sensitivity for MRD detection, although not statistically significant. However, the sensitivity NGF is still superior than either method of PET/CT. In terms of PFS, NGF and PET/CT are both independent prognostic factor.

Reduced Intensity Reinduction Followed By Blinatumomab Achieves Excellent MRD Clearance with Reduced Toxicity and Facilitates Timely Transplant in Children and Young People with Relapsed B-Precursor Acute Lymphoblastic Leukemia

Introduction Despite the emergence of effective novel immunotherapies, the outcome of relapsed pediatric B-cell acute lymphoblastic leukemia (B-ALL) remains poor due to treatment-related mortality (TRM) and resistant disease. In response to accumulating evidence on the efficacy and low toxicity of blinatumomab in relapsed B-ALL and the availability of highly active CD19-targeted chimeric antigen receptor T-cell therapy (CART), we redesigned the United Kingdom (UK) relapse treatment pathway, based on two key guiding principles: 1) to reduce chemotherapy burden and associated toxicity through a move away from the highly intensive ALL R3 backbone towards increased reliance on blinatumomab to clear disease, and 2) to identify treatment failures early and direct them to CART, given the poor responses reported with hematopoietic stem cell transplant (HSCT) in this context. Methods Patients were treated with UKALL induction chemotherapy (<16yr: 3-drugs; >16yr: 4-drugs) until adequate blast clearance. Patients with blasts <5% at Day 15 progressed directly to blinatumomab; remaining patients continued to Day 28. Following reinduction, patients received up to 2 cycles of blinatumomab as a single agent. HR patients (early/very early relapses and/or HR cytogenetics) proceeded to HSCT once minimal residual disease (MRD) <0.01%. Those with high-risk (HR) isolated central nervous system (CNS) disease had the option to proceed directly to HSCT following CSF blast clearance without blinatumomab. All Standard risk (SR) patients continued on chemotherapy alone. Patients who were refractory after re-induction (>25% disease), blinatumomab (MRD >0.01%), or for whom there was no available donor were considered for CART. All patients were required to be discussed at a national tumour board, and data were subsequently collected every 3 months for analysis. Events were defined as death, relapse, and secondary cancer. Results Between September 2018 and July 2022, 111 patients were treated on the pathway; 63 (56.8%) were HR and 48 (43.2%) were SR. There were 26 patients >15yr, 3 Infant ALL, 2 Ph+ ALL and 4 with Down Syndrome. Induction therapy achieved disease reduction to <5% and CNS clearance in 98 patients (88%). Of the 90 patients with BM involvement, 52.2% required only 15 days of induction therapy. Induction failure (>25% blasts) occurred in 6.3%, comparable to the 7.1% using the R3 induction in the COG AALL1331 trial (p=1.00); 6/7 patients with induction failure successfully underwent CART infusion. The rate of end of induction MRD <0.01% in the HR group was also similar to COG AALL1331 (30% vs. 27.4%, p=0.669). Importantly, there were no cases of TRM with the reduced intensity induction, compared to 2.4-4% reported with the ALL R3 induction (p=0.06). Ninety patients received blinatumomab, of whom 87% achieved a complete MRD response, with grade 3 or 4 treatment-related toxicity in 11 patients (12.2%). Amongst HR patients, 86.8% underwent HSCT, significantly more than in the blinatumomab-treated IR/HR arm of COG AALL1331 (66%, p=0.02). With a median follow-up of 12 months (range 2-49), 19% of HR patients and 8.3% of SR patients have relapsed, comparable to results achieved in the blinatumomab-treated arm of the COG AALL1331 trial. There were no deaths in the SR group, and 12 deaths in the HR group (6 due to relapse/refractory disease, 6 due to post-HSCT TRM). Conclusions Our findings demonstrate that a reduced intensity reinduction can achieve equivalent disease control to the more intensive ALL R3 induction, with a substantial reduction in TRM. Although follow-up is short, consolidative blinatumomab achieved very high rates of MRD clearance, allowing a greater number of HR patients to reach potentially curative therapy with HSCT, the key predictor of outcome in the COG AALL1331 trial. We propose that our strategy represents a new standard of care for reinduction therapy in relapsed childhood B-ALL. DO and AV are joint senior authors Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Time-Limited Maintenance with Ibrutinib after First-Line Therapy and the Incremental Impact on Minimal Residual Disease (MRD) for Patients with Chronic Lymphocytic Leukemia (CLL)

Background: Inhibitors of Bruton's tyrosine kinase (BTKi) are approved and clinically used as indefinite treatments (until disease progression) irrespective of the depth of response in patients (pts) with CLL. Despite impressive, sustained efficacy, their ability (as single agent) to target residual disease clone post induction treatment in CLL is not well established. As indefinite treatment is associated not only with cumulative toxicity but also high cost and compromised quality of life, we investigated the benefit of time-limited maintenance treatment (3 years) with ibrutinib to assess the ability of a BTKi to further deepen antitumor response achieved post induction treatment. Methods: CLL pts (n=35) who had residual disease (by clinical or molecular assessment) after primary induction treatment were enrolled on a prospective phase 2 trial (NCT02649387). MRD assessed in blood (PB)/bone marrow (BM), was determined by 8-color flowcytometry (1x10-4) and defined as ≥1 CLL cell per 10,000 leukocytes or ≥0.01%. Patient were eligible if they had detectable residual (non-progressive) disease within 1 year of completing induction and no prior ibrutinib (or other BTKi) treatment. Ibrutinib 420mg PO QD was given on days 1-28 of a 28-day cycle for up to 36 cycles. Clinical (iwCLL 2008 response criteria) and molecule response MRD (on PB) was done at baseline and then every 3 cycles while on treatment. BM-MRD evaluation was conducted only if PB-MRD was negative (on two separate timepoints 3 months apart). Monitoring of the PB-MRD was continued for 24 months after completing time-limited maintenance with ibrutinib. Cumulative toxicity was assessed using the CTCAE v4.0 and iwCLL criteria. Results: Patient characteristics are summarized in Table 1. In 34 out of 35 (97%) patients, obinutuzumab alone was used as induction therapy. The median follow up is 38.6 months (range 0.9-73.2) and the median number of maintenance cycles completed is 34 (range 1-36). Of the 33 patients assessed for PB-MRD, 8 (24.2%) pts became MRD- on at one assessment. Five patients had BM-MRD assessment with 1 (2.8%) converting to MRD-. The median time to achievement of MRD- was 4.4 months (range 2.7-34.7). We noted that single agent ibrutinib was unable to deliver stringent MRD-negativity (defined as achievement of MRD- status both in PB and BM sustained over 2 consecutive evaluations at least 3 months apart).To assess if pre-maintenance response could impact MRD post-treatment; we note that out of the 8 pts that achieved MRD-, 2 (25%) started with CR and 6 (75%) with nPR/PR at registration. Deepening of response was noted in 5 pts (14.3%) after a median of 14 cycles [3 (8.6%) pts improved nPR to CR and 1(2.9%) went from nPR to CRi and 1 (2.9%) went from a CRi to a CR]. Nine patients proceeded to subsequent treatment with the median time to next treatment (mTTNT) of 32.5 m (range: 12.1 - 61.0). One patient died due to a failure to thrive and acute kidney injury on dialysis and six pts have progressed. The median PFS for the entire cohort was 41.1 m (95% CI: 39.8 - NE). The most commonly reported adverse events (AEs) (seen in >10% pts) regardless of attributions were thrombocytopenia (24 pts; 68.6%), anemia (12 pts; 34.3%), neutropenia (9 pts; 25.7%), lymphopenia (9 pts; 25.7%), hypertension (9 pts; 25.7%), leucopenia (6 pts; 17.1%), fatigue (5 pts; 14.3%), headache (4 pts; 11.4%), and skin infections (4 pts; 11.4%). Atrial fibrillation (AFib) was noted in 3 pts (8.6%). Conclusion: We conclude that BTK targeting with ibrutinib alone although able to clear PB-MRD (24.2%), had limited efficacy to eradicate BM-MRD (2.8%) demonstrating a differential impact in these two disease compartments. While the rate of complete MRD eradication was not necessarily high (when compared to recent data with BTKi/BCL2i combination regimens) MRD-kinetics over time demonstrated progressive decrease in disease burden and response improvement with maintenance treatment. The sequential single agent treatment approach was well tolerated, and the time-limited therapy aimed at minimizing cumulative toxicity seemed to be effective in lowering rate of Afib (compared to historical control ~16%). This data warrants further investigation of time-limited maintenance therapy with newer, more favorably tolerated BTKi and/or Bcl2i post induction treatment(s) to optimize response vs. cumulative toxicity. Further evaluation of sequential time-limited treatments in CLL is warranted. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Final Results from UKALL60+ (NCT01616238), a UK National Cancer Research Institute Trial for Older People with De Novo Acute Lymphoblastic Leukaemia

Background Improvements in outcome for older patients with Acute Lymphoblastic Leukaemia (ALL) have not kept pace with those for younger persons. Whether there is a survival benefit to more 'intensive’ chemotherapy for older patients and what is the 'pay-off’ in terms of adverse events and duration of inpatient hospitalisation is unclear. Few ALL trials recruit older individuals, with 55 or 60 years being common upper age limits. UKALL60+ (NCT 01616238) a UK National Cancer Research Institute Adult ALL subgroup study, was designed to investigate the safety, tolerability and outcomes of varied intensity chemotherapy protocols for patients ≥ 60 years (y) (55y with comorbidities, no upper age limit) with de novo ALL. Methods Physicians/patients with BCR::ABL1 negative ALL chose freely between three trial chemotherapy pathways; B: based on the UKALL14 adult ALL regimen, but modified to reduce common toxicities eg asparaginase was excluded and dose intensity of certain drugs eg anthracyclines, intravenous (IV) methotrexate were reduced C: the intensive in-patient regimen as used in HOVON100 and D: a regimen designed to be delivered as an 'outpatient', wherein vincristine was the only IV-administered agent. A, tyrosine kinase inhibitor combined with modest intensity chemotherapy was offered for patients with BCR::ABL+ ALL. Regimens A-D all included two full years of maintenance therapy. E was a registration-only pathway with free choice of therapy. Baseline characteristics collected included Charlson index, ECOG, Karnofsky, IADL and CRASH scores. The primary end point was complete remission (CR) rate. Secondary end points included EFS and OS at 1 year, treatment related mortality (TRM), minimal residual disease (MRD) response (patient-specific Ig/TCR quantification by PCR, performed in a central laboratory), adverse event (AE) rates, duration of inpatient hospitalisation and assessment of the relationship between baseline characteristics and treatment option chosen. Quality of life was assessed throughout; data are not yet analysed. Results Between 01/2013 and 11/2018, 126 patients aged 55-83y were recruited, of whom 5 were ineligible (misdiagnosis) leaving 121 analysable. Fifteen pursued registration only, whereas 106/121 elected treatment pathways A-D. Patient characteristics as well as main outcome measures are shown in panel (i). Those receiving regimen D were significantly older than those allocated to B (73 vs 67y p=0.0001). They were moderately more dependent (IADL score 27 vs 28, p =0.04) with slightly higher Charlson index (8 vs 7, p=0.038), suggesting a mix of drivers for therapy selection. Induction CR rate was 92% for pathway A recipients (BCR::ABL1+), 70.6% for B (intermediate intensity), 55.6% for C (most intensive) and 47.6% for D (least intensive), with the latter low rates being due to TRM and lack of disease response, respectively. Strikingly few (N=22, 18.2%, overall) patients achieved an MRD negative remission, with zero complete MRD responses in the low intensity pathway D. Median EFS (mo) was A 23.0 (11.8 - 54.3), B 18.1 (11.3 - 24.2), C not reached, and D 10.9 (5.0 - 13.2). AE forms were available for 102/106 patients. Grade 3/4 AEs rates were equivalent across the pathways; A 22/25 (88%), B 45/49 (91.8%), C 7/8 (87.5%) and D 19/20 (95%), although febrile neutropenia was uncommon in A 3/23(12%) and D 3/20 (15%) but common in B 23/49 (46.9%) and C 6/8(75%). Duration of hospitalisation as a percentage of total time on therapy was A 6%, B 14%, C 24%, and D 8% (p=0.026). Most inpatient days were during induction: 23%, 62%, 76% and 32% respectively (p<0.001). We compared the survival of all UKALL60+ participants to the N=65 patients >60 y treated on the UKALL14 study for patients aged 25-65 y between 05/2012 and 07/2017. Although remission rates were higher for those >60y treated on UKALL14 (87.3%), neither EFS (panel ii) nor OS differed between the trials, suggesting that outcome after chemotherapy treatment is poor across the board for older patients with ALL. Conclusion Our prospective trial data suggest that maximising chemotherapy intensity in older patients with ALL does not confer long-term clinical benefit for the majority of patients. Older patients should be counselled carefully as to the likely outcome of treatment with chemotherapy alone and offered novel therapies or trials of those agents as de novo therapy, wherever possible. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Minimal Residual Disease in Adult Acute Lymphoblastic Leukemia: Egyptian Experience.

Background:Acute lymphoblastic leukemia (ALL) is a clonal disease that affects early lymphoid progenitors in the bone marrow. Minimal residual disease (MRD) is assessed by different methods to monitor disease kinetics after treatment. Aim:to Assess MRD post-induction, at 6 and 12 months after intensive chemotherapy in adult patients with ALL. Patients and Methods: Seventy adult newly diagnosed acute lymphoblastic leukaemia patients were enrolled between July 2018 and July 2019 at the Clinical Hematology Unit, Ain Shams University hospitals, Egypt. MRD was assessed on the bone marrow samples using multi-parameter four color flow cytometry with 0.01% cut-off; below which cases are deemed MRD negative. Results:After the end of induction period, 13 out of 46 patients (28%) had positive MRD. However, MRD positivity is demonstrable in 14/32(43.8%), and 10/28(35.7%) patients at 6 and 12 months; respectively. MRD positivity was significantly associated with older age group (more than 39 years) and high NCCN risk stratum with p-values <0.05. Moreover, most of MRD positive patients at 12 months of therapy were of T-ALL immunophenotype (P value 0.002). Patients with complete remission and negative MRD exhibited significantly higher overall survival when compared to patients having MRD positivity (P value 0.027). Conclusion:MRD is a powerful predictor of outcome in ALL and its positivity at different time points is associated with poor prognostic factors as well as survival outcomes.

High tumor burden before blinatumomab has a negative impact on the outcome of adult patients with B-cell precursor acute lymphoblastic leukemia. A real-world study by the GRAALL.

Blinatumomab is a bispecific T-cell engager approved for B-cell precursor acute lymphoblastic leukemia (B-ALL) with persistent minimal residual disease (MRD) or in relapse. The prognostic impact of tumor load has been suggested before other immunotherapies but remains poorly explored before blinatumomab. We retrospectively analyzed the outcome of 73 patients who received blinatumomab either in first complete remission (CR) with MRD (n=35) or at relapse (n=38). Among MRD patients, 91% had MRD >0.01% before blinatumomab, and 89% achieved complete MRD response after blinatumomab. High pre-blinatumomab MRD levels were associated with shorter relapse-free survival (P=0.049) and overall survival (OS) (P=0.011). At 3 years, OS was 33%, 58% and 86% for pre-blinatumomab MRD >1%, between MRD 0.1-1% and <0.1% respectively. Among relapsed patients, 23 received blinatumomab with overt relapse and 15 were in complete response (CR) after bridging chemotherapy. At 3 years, overall CR rate was 68% and complete MRD response rate was 84%. Patients who directly received blinatumomab had shorter relapse-free survival (P=0.033) and OS (P=0.003) than patients bridged to blinatumomab. Three-year OS was 66% in the latter group compared to 16% in the former group. Our observations suggest that pre-blinatumomab tumor burden should help to design more tailored strategies including tumor load reduction in relapsed patients.

What Is the Role of HSCT in Philadelphia-Chromosome-Positive and Philadelphia-Chromosome-Like ALL in the Tyrosine Kinase Inhibitor Era?

Previously, the outcome of paediatric Philadelphia-chromosome–positive (Ph+) ALL treated with conventional chemotherapy alone was poor, necessitating the use of haematopoietic stem cell transplantation (HSCT) for the best outcomes. The recent addition of tyrosine kinase inhibitors (TKIs) alongside the chemotherapy regimens for Ph+ ALL has markedly improved outcomes, replacing the need for HSCT for lower risk patients. An additional poor prognosis group of Philadelphia-chromosome–like (Ph-like) ALL has also been identified. This group also can be targeted by TKIs in combination with chemotherapy, but the role of HSCT in this population is not clear. The impact of novel targeted immunotherapies (chimeric antigen receptor T cells and bispecific or drug-conjugated antibodies) has improved the outcome of patients, in combination with chemotherapy, and made the role of HSCT as the optimal curative therapy for Ph+ ALL and Ph-like ALL less clear. The prognosis of patients with Ph+ ALL and persistent minimal residual disease (MRD) at the end of consolidation despite TKI therapy or with additional genetic risk factors remains inferior when HSCT is not used. For such high-risk patients, HSCT using total-body-irradiation–containing conditioning is currently recommended. This review aims to provide an update on the current and future role of HSCT for Ph+ ALL and addresses key questions related to the management of these patients, including the role of HSCT in first complete remission, MRD evaluation and related actions post HSCT, TKI usage post HSCT, and the putative role of HSCT in Ph-like ALL.

Real-World Multicenter Experience in Tumor Debulking Prior to Blinatumomab Administration in Adult Patients With Relapsed/Refractory B-Cell Precursor Acute Lymphoblastic Leukemia.

Blinatumomab is an immunotherapeutic agent with dual specificity for CD3 and CD19 that is approved for the treatment of relapsed/refractory B-cell precursor acute lymphoblastic leukemia (R/R B-ALL). A steroid based pre-treatment is recommended before administering blinatumomab to patients with a high tumor burden to minimize the risk of tumor lysis syndrome, but the optimal debulking regimen and whether it can improve responses remain unclear. The present study retrospectively evaluated real-world outcomes following tumor debulking and blinatumomab infusion in R/R B-ALL adult patients treated at 7 Italian centers. Data were collected from 34 patients. The choice of the cytoreductive therapy was made by the treating clinician on an individual patient basis; regimens included chemotherapy (n=23), steroids (n=7) and tyrosine kinase inhibitors alone or in combination (n=4). The rate of complete responses (CR) and complete minimal residual disease (MRD) responses in CR patients were 67.6% and 81% respectively, after 2 cycles of blinatumomab. Moreover, among patients with a high tumor burden 50% obtained a CR, with 89% of them also achieving a complete MRD response. Favorable responses were also obtained in patients over 50 years of age at treatment initiation. Overall, 7 of 23 patients in CR after blinatumomab underwent hematopoietic stem cell transplantation. The results of this retrospective study highlight the heterogeneity in the use of pre-blinatumomab tumor debulking in real-life clinical practice. Nonetheless, debulking pre-treatment enhanced responses to blinatumomab compared to historic studies, indicating that this strategy may help to improve outcomes for R/R B-ALL patients.

Outcome of Therapy-Related Myeloid Neoplasms with Venetoclax-Based Therapy

Outcome of Therapy-Related Myeloid Neoplasms with Venetoclax-Based Therapy

A Phase 2 Study to Test the Feasibility, Safety and Efficacy of the Addition of Blinatumomab to the Interfant06 Backbone in Infants with Newly Diagnosed KMT2A-Rearranged Acute Lymphoblastic Leukemia. a Collaborative Study of the Interfant Network

▪Background:Infant acute lymphoblastic leukemia (ALL) is a rare disease with dismal outcome. While outcomes for older children have improved, with event-free survival (EFS) currently above 85%, newly diagnosed infants (<1 year of age) with KMT2A-rearranged ALL have an 1-year EFS of 54.8% (SE 2.3) and a 3-year EFS of 39.6% (SE 2.3) (48% and 23% for medium risk (MR) and high risk (HR) patients, respectively). Ninety percent of all relapses occur during treatment, 66% within one year of diagnosis. Survival after relapse is only 20%. Intensifying chemotherapy with the Interfant06 protocol has not improved the outcome for infant ALL over the last two decades (Pieters et al., JCO 2019), hence there is an urgent need to improve upfront treatment. We studied the safety and efficacy of blinatumomab, a bispecific T-cell engager antibody targeting CD19, in infants with newly diagnosed KMT2A-r ALL.Methods:We conducted a prospective, single-arm, international, multicenter, phase 2 study. Newly diagnosed patients <1 year of age with KMT2A-r ALL treated according to the Interfant06 protocol and with a M1/M2 marrow at the end of induction (EOI) were eligible to receive one course of blinatumomab (15ug/m 2/day, 28 day continuous infusion) after induction (Figure 1). Minimal residual disease (MRD) was measured at EOI (TP2), during blinatumomab (TP blina1 day15 and TP blina2 day29), before MARMA (TP4) and OCTADAD/hematopoietic stem cell transplant (HSCT) (TP5), and at the start of maintenance (TP6) using MLL and/or Ig/TCR polymerase chain reaction. HR KMT2A-r infant ALL was defined as age <6 months at diagnosis AND white blood cell count≥300x10 9/L and/or poor prednisone response. All other KMT2A-r patients were classified as MR. MR patients with MRD levels >0.05% before OCTADAD and all HR patients in complete remission were eligible for HSCT. (Serious) Adverse Events ((S)AEs) were collected from the start of blinatumomab until the next treatment block. Outcome data were compared to historical controls.Results:Twenty-eight patients were enrolled. Baseline characteristics are shown in Table 1. The median follow-up was 11 months (range 1.5-33 months). All patients received the full course of blinatumomab without treatment interruptions. Seven SAEs were reported during blinatumomab (3 fever, grade 1 and 4 infections, grade 3-4). None of the patients experienced neurological (S)AEs. In total, 70 AEs were reported, the most frequent grade >3 adverse events were febrile neutropenia (n= 2), anemia (n=5), and elevated GGT (n=2). MRD negative complete response occurred in 54% (n=15/28) at TP blina1, as well as at TP blina2 (after 2 and 4 weeks of blinatumomab, Table 2), which tended to be higher compared to the end of consolidation in Interfant06 (40%, p=0.16). There were 89% (25/28) of patients who were MRD negative or not quantifiable (<0.05%) at TP blina2. None of the MR patients had an indication for HSCT based on high MRD before OCTADAD, compared to 20% in Interfant06, however one patient was transplanted per investigator's discretion. All MR patients who continued chemotherapy became MRD negative during further treatment. MRD negative complete response at the end of blinatumomab was more frequently found in MR compared to HR patients (68% vs 22%, p=0.0418) and in patients with low MRD at EOI (<0.05%) compared to patients with high MRD at EOI (76% vs 18 %, p=0.0056). The 1-year EFS was 96.2% (SE 3.8). One death in first complete remission (CR1) occurred just before HSCT, which was not blinatumomab related (tracheal bleeding due to a tracheal cannula). One MR patient with high MRD at EOI had a combined CD19 positive relapse in the bone marrow and CNS at the end of maintenance, and is in continuous CR2 after HSCT.Conclusion:This is the first trial to use blinatumomab in infants with newly diagnosed KMT2A-r ALL. Blinatumomab added to the Interfant06 backbone was very well tolerated, and has promising efficacy in terms of a high rate of complete MRD response and short term EFS. Longer follow-up is awaited, but the low relapse rate after blinatumomab is remarkable, given that in historical controls relapses occur frequently and early, during therapy. Given these findings, blinatumomab will be implemented for all infants with newly diagnosed KMT2A-r ALL in the next Interfant21 protocol. [Display omitted] DisclosuresNysom: Y-mAbs: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: teaching; EUSA Pharma: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees, Other: teaching. Biondi: Amgen: Honoraria; Incyte: Consultancy, Other: Advisory Board; Bluebird: Other: Advisory Board; Novartis: Honoraria; Colmmune: Honoraria. OffLabel Disclosure:Investigational use of blinatumomab

Results of the Full Pediatric, Minimal Residual Disease (MRD)-Oriented Trial LAL-RI/2008 for Adolescents and Young Adults (AYA) with Standard Risk (SR), Philadelphia Chromosome-Negative Acute Lymphoblastic Leukemia (ALL)

Background and objective. Full pediatric or pediatric-derived trials constitute the treatment of choice for AYA with SR-ALL. In the MRD era, patients (pts) with SR factors at baseline with poor MRD clearance should be considered as HR patients. The objectives of the full pediatric LAL-RI/2008 trial (NCT02036489) from the Spanish PETHEMA group were to assess the proportion of AYA with SR-ALL at baseline who have HR features based on poor early cytological response and/or poor MRD clearance, and to compare their prognosis with that from those pts who achieve good early cytological response and good MRD clearance.Patients and methods. SR ALL was defined in adolescents (age 15 to 18 years) and young adults (age 19 to 29 years) fulfilling all the following criteria: WBC count ≤30 × 109/L, and absence of t(9;22), t(1;19), t(4;11) or any other 11q23 rearrangements. Induction therapy included vincristine (VCR), prednisone (PDN), daunorubicin (DNR) and native E. coli asparaginase (ASP) for 4 weeks. Pts who achieved complete remission (CR) and MRD<0.1% proceeded to consolidation-1 (high-dose methotrexate [MTX], intermediate-dose ARA-C, etoposide and mercaptopurine [MP]), consolidation-2/reinduction (VCR, dexamethasone, DNR, cyclophosphamide and ASP), maintenance-1 (MP and MTX with monthly reinductions with VCR, PDN and ASP until the end of the 1st year) and maintenance-2 (MP and MTX without reinductions until the end of the 2nd year). CNS prophylaxis consisted of triple intrathecal therapy (MTX, ARA-C and hydrocortisone, 16 doses throughout the treatment). Pts with poor early cytological response (BM blast cells >10% on day 14 of induction), MRD level >0.1% (assessed by flow cytometry) at CR or MRD level >0.05% at any time after CR were considered as high risk (HR) pts and received the ALL-HR trial consisting of intensive chemotherapy followed by allogeneic hematopoietic stem cell transplantation (alloHSCT) (Ribera JM et al. J Clin Oncol 2014; 32:1595-604).Results. Between 2008 and 2017, 79 eligible pts were treated according to the ALL-RI-08 protocol. Median age (range) was 20 years (15-29), 34 (43%) were adolescents and 45 (57%) YA. The mean (SD) WBC count was 10 (9) x109/L, and 73 patients (94%) had B-cell precursor ALL. Two patients are on treatment and 74 out of the remaining 77 (96%) achieved the CR. From the 77 pts, 15 had poor early cytological response, 3 had MRD >0.1% at the time of CR and 1 pt showed reappearance of MRD level >0.05% during maintenance. In all, 19 patients were considered as HR. Of the 58 patients who remained SR and followed the LAL-RI/2008 protocol, 14 relapsed (7 during treatment and 7 off therapy), whereas in the HR group, 3 were resistant, 4 relapsed and 2 died by toxicity (transplant-related in 1 out of 4 pts submitted to alloHSCT). Table 1 shows the DFS, OS and cumulative incidence of relapse (CIR) at 5-yrs for the whole series, the patients remaining SR and those who turned HR. Of note, OS was lower in the HR pts (Figure 1). On comparison with the results of the ALL-RI-96 trial (same inclusion criteria, same treatment but no follow-up by MRD, Ribera JM et al. J Clin Oncol 2008; 26:1843-9), no differences were observed in DFS, OS and CIR (Table 1).ConclusionsTwenty-five percent of AYA pts with SR ALL at baseline are in fact HR based on slow early cytological response to therapy and/or poor MRD clearance. High-risk pts showed lower OS despite being moved to a HR protocol.Supported in part by grants RD12/0036/0029 (RTICC, FEDER), PI14/01971 FIS, Instituto Carlos III, and SGR225 (GRE), Spain. [Display omitted] DisclosuresRibera:Celgene: Honoraria; Gilead: Honoraria; Janssen: Honoraria; Roche: Honoraria; ARIAD: Research Funding, Speakers Bureau; Incyte: Research Funding, Speakers Bureau; Pfizer: Research Funding, Speakers Bureau; Amgen Inc.: Research Funding, Speakers Bureau. Montesinos:Celgene Corporation: Honoraria, Research Funding.

Safety and Efficacy of Blinatumomab in Combination with a Tyrosine Kinase Inhibitor for the Treatment of Relapsed Philadelphia Chromosome-Positive Leukemia

Safety and Efficacy of Blinatumomab in Combination with a Tyrosine Kinase Inhibitor for the Treatment of Relapsed Philadelphia Chromosome-Positive Leukemia

Utility of Leukemic Stem Cells Markers in Determining Minimal Residual Disease in Patients with AML

Introduction: Minimal residual disease (MRD) assessments are being increasingly used to define prognosis in patients with acute myeloid leukemia (AML). However, data suggests that a proportion of patients found to be MRD negative experience leukemia relapse. These relapses are thought to be related to the persistence of leukemia stem cells (LSC) that survive chemotherapy. Recent studies have identified a number of LSC antigens that may be useful to follow LSC populations including CLL1, CD123 and CD47. We hypothesized that the use of a routine antibody panel in conjunction with CD123 and CLL1 specific antibodies will allow for more accurate determination of MRD using multiparametric flow cytometry (MPFC) and better identification of patients destined to relapse.Methods: In this single center prospective study we evaluated the diagnostic bone marrow samples of all newly diagnosed patients with AML (excluding APL) for leukemia associated immunophenotypes (LAIP's) using MPFC and a panel of antibodies targeted towards myeloid, lymphoid and LSC markers. LAIP's were scored as a percentage of the bulk blast population which was defined using plots of Side Scatter (SCC) vs. CD45. LSC compartment was defined as CD34+CD38-CD123+ or CD34+CD38-CLL1+. Bone marrow samples from non-leukemic patients were used to identify the background level of CD123 and CLL1 positivity. Samples were considered MRD positive if having >0.1% of a specific LAIP as a function of the bulk blast population.Results: Over the study duration, 88 patients with newly diagnosed AML received intensive chemotherapy (Table1). Complete MRD data (routine and LSC markers) was available for 58 patients had at the end of induction and 31 patients at the end consolidation (EOC). For the 58 patients with end-of-induction (EOI) MRD data the diagnostic sample revealed CD123+ LSC and CLL1+ LSC at a frequency of >0.1% in 30 (51.7%) and 28 (48.3%) patients respectively and at a frequency of <0.1% in 24 (25.9%) and 26 (44.8%) patients respectively. Data was not available for 4 patients.Following a single induction chemotherapy cycle 52/58 (89.7%) patients were in complete remission. At the EOI, 26/58 (44.8%) patients were found to be MRD negative using the standard antibody panel. Only 3/30 patients (10%) who had CD123+ LSC and 2/28 patients who had CLL1+ LSC at diagnosis were found to be negative at the EOI. However, 21/24 (87.5%) patients that were negative for CD123+ LSC and 22/24 (85%) patients that were negative for CLL1+ LSC at diagnosis were found to be positive for CD123+ LSC and CLL1+ LSC at the EOI, respectively. At the EOC, 31 patients were assessed for routine and LSC based MRD. Amongst these patients 16 (51.6%) were MRD negative using routine markers, 13 (41.9%) were negative CD123 and only 6 (19.4%) were negative for CLL1.There was no relationship between relapse rates and the MRD status at the EOI or EOC using either standard MRD markers, CD123 or CLL1. Although not statistically significant we observed that only 1 of 6 (16.7%) patients that was negative for CLL1+ LSC at the end of consolidation relapsed in contrast to 11 of 25 (44%) patients that were positive for CLL1+ LSC (p=0.4).After a median follow-up of 11.3 months, the median relapse free survival for patients that were positive for CLL1+ LSC at the EOC was 13.8 months and was not achieved for patients negative for CLL1+ LSC (p=0.4). Similarly, there was no significant difference in the RFS for patients that were MRD positive or negative for routine MRD markers (16.8 vs. 13.8 months, p=0.94) or for CD123 (13.8 vs. 16.8 months, p=0.73). The median overall survival (OS) for the entire cohort was not achieved. There was no significant difference in the OS for patients based upon MRD status at the EOC when using standard MRD markers, CLL1 (Figure 1) or CD123 (Figure 2).Conclusions: This proof-of-concept study suggests that the CLL1+ and CD123+ LSC can be identified at diagnosis at very low levels relative to the bulk blast population. Surprisingly, patients who were negative for CD123+ and CLL1+ LSC at diagnosis were often found to be positive at EOI. This may be related to a reduction in the overall blast population due to chemotherapy, but persistence of the original LSC population. Larger studies are necessary to explore the impact of persistent LSC markers on clinical outcomes. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.