Positive B-cell Acute Lymphoblastic Leukemia Research Articles

Outcomes of children and young adults with B-cell acute lymphoblastic leukemia given blinatumomab as last consolidation treatment before allogeneic hematopoietic stem cell transplantation.

Blinatumomab has remarkable efficacy in patients with relapsed/refractory (r/r) or measurable residual disease (MRD)-positive B-cell acute lymphoblastic leukemia (B-ALL). In many patients, blinatumomab treatment is followed by allogeneic hematopoietic stem cell transplantation (HSCT). However, the influence of blinatumomab on HSCT outcomes in children and young adults (YA) remains to be fully elucidated. We conducted a single-center, retrospective analysis on patients given blinatumomab as last treatment before HSCT. Seventy-eight pediatric and YA patients were evaluated. With a median follow-up of 23.23 months, the 2-year disease-free (DFS) and overall survival (OS) probability were 72.2% and 89.2%, respectively, with a 2-year cumulative incidence (CI) of non-relapse mortality (NRM) of 2.6%. A trend toward improved 2-year DFS, but not OS, was noted in patients transplanted in first complete remission (CR1) (92.9%) compared to those in second or greater remission (CR2/3) (68.5%, p=0.18) due to a lower CI of relapse (0% vs. 29.9%, p=0.05). Among CR2/3 patients, those receiving the sequential combination of inotuzumab and blinatumomab had a significantly lower CI of relapse as compared to those who did not receive inotuzumab (9.5% vs. 40.4%, p=0.023). Relapse after HSCT occurred in 16 patients, all exhibiting CD19-positive blasts; 10 of them received anti-CD19 chimeric antigen receptor T-cell (CAR-T) therapy and 2 inotuzumab as salvage therapy, leading to a 2-year post-relapse OS of 52.7%. Our results indicate that HSCT following blinatumomab in children and YA with B-ALL is highly effective, being associated with low NRM and not affecting the efficacy of subsequent salvage immunotherapies, including CAR-T cells.

CAR-T Therapy Followed by Hematopoietic Stem Cell Transplantation Can Improve Survival in Children Relapsed/Refractory Philadelphia Chromosome-positive B-cell Acute Lymphoblastic Leukemia.

Philadelphia chromosome (Ph)-positive B-cell acute lymphoblastic leukemia (ALL) has a high complete remission (CR) rate, but relapse and prolonged measurable residual disease remain serious problems. We sought to describe the CR rate measurable residual disease negative rate and address the results and safety of pediatric patients who underwent after receiving chimeric antigen receptor (CAR) specific for CD19 (CAR-19) followed by hematopoietic stem cell transplantation (HSCT) for the treatment of Ph-positive ALL. A descriptive study was conducted at Peking University People's Hospital from September 2013 to January 2021. 13 patients with relapsed/refractory Ph-positive B-ALL who received CAR-T therapy followed by allo-HSCT were included. We concentrated on the overall patient survival and CR rate. The median time between CAR-T therapy and allo-HSCT was 58 days. Among all the patients, the CR rate was 100%, the flow cytometry negativity rate was 84.62%, and the BCR-ABL negativity rate was 53.85% at 1 month after CAR-T infusion. All the patients achieved a major molecular response in 6 months after HSCT. After a median follow-up of 45 months, the 3-year OS rate was 66.7%, and the 3-year DFS rate was 61.5%. The 3-year OS rate of patients with BCR-ABL-positive pre-HSCT was significantly lower than that in the BCR-ABL-negative group (40.0% vs. 85.7%, P =0.042). Also, the same trend was observed for the 3-year DFS rate but did not differ significantly (40.0% vs. 75.0%, P =0.233). CAR-T therapy followed by allo-HSCT can be a safe and effective treatment for Ph-positive B-ALL pediatric patients.

Impact of minimal residual disease response and of status of disease on survival after blinatumomab in B-cell acute lymphoblastic leukemia: results from a real-life study.

Blinatumomab is a bispecific T-cell engager approved for relapsed/refractory and minimal residual disease positive B-cell Acute Lymphoblastic Leukemia. We conducted a retrospective study evaluating the outcome of Blinatumomab. The impact of clinical and treatment-related variables on cumulative incidence of relapse/progression (CIRP), event-free (EFS) and overall survival (OS) was analyzed. From January 2016 to December 2022 50 Ph'- (37) and Ph+ (13) B-ALL patients received Blinatumomab. The median age was 37. Indications to blinatumomab were relapsed/refractory B-ALL in 29 and MRD-positive in 21 patients. Blinatumomab was the 2nd and 3rd line in 40 and in 10 patients, respectively. Twenty patients were treated pre-transplantation, ten were treated for relapse after transplant, twenty were not eligible for transplant. Out of 29 patients treated for relapsed/refractory disease, 16 (55%) achieved complete response and 12 achieved MRD-negativity. Out of 21 patients treated for MRD, 16 (76%) achieved MRD-negativity. At a median follow-up of 46 months the median EFS and OS were 11.5 and 16.2 months. The CIRP was 50%. In univariate analysis age, disease-status (overt vs. minimal disease) at blinatumomab, bridging to transplant after blinatumomab and MRD-response resulted significant for EFS and OS. In multivariate analysis only disease-status and MRD-response retained significance both for EFS and OS. Disease-status and MRD-response resulted significant for EFS and OS also after censoring at HSCT. This retrospective study on B-ALL patients treated with blinatumomab confirms a superior outcome for MRD-responsive over MRD non-responsive patients. Survival depends also on the disease-status prior treatment.

Asciminib Maintains Antibody-Dependent Cellular Cytotoxicity against Leukemic Blasts.

B cell acute lymphoblastic leukemia (B-ALL) is characterized by an accumulation of malignant precursor cells. Treatment consists of multiagent chemotherapy followed by allogeneic stem cell transplantation in high-risk patients. In addition, patients bearing the BCR-ABL1 fusion gene receive concomitant tyrosine kinase inhibitor (TKI) therapy. On the other hand, monoclonal antibody therapy is increasingly used in both clinical trials and real-world settings. The introduction of rituximab has improved the outcomes in CD20 positive cases. Other monoclonal antibodies, such as tafasitamab (anti-CD19), obinutuzumab (anti-CD20) and epratuzumab (anti-CD22) have been tested in trials (NCT05366218, NCT04920968, NCT00098839). The efficacy of monoclonal antibodies is based, at least in part, on their ability to induce antibody-dependent cellular cytotoxicity (ADCC). Combination treatments, e.g., chemotherapy and TKI, should therefore be screened for potential interference with ADCC. Here, we report on in vitro data using BCR-ABL1 positive and negative B-ALL cell lines treated with rituximab and TKI. NK cell activation, proliferation, degranulation, cytokine release and tumor cell lysis were analyzed. In contrast to ATP site inhibitors such as dasatinib and ponatinib, the novel first-in-class selective allosteric ABL myristoyl pocket (STAMP) inhibitor asciminib did not significantly impact ADCC in our settings. Our results suggest that asciminib should be considered in clinical trials.

3D Amplified Single-Cell RNA and Protein Imaging Identifies Oncogenic Transcript Subtypes in B-Cell Acute Lymphoblastic Leukemia.

Simultaneous in situ detection of transcript and protein markers at the single-cell level is essential for gaining a better understanding of tumor heterogeneity and for predicting and monitoring treatment responses. However, the limited accessibility to advanced 3D imaging techniques has hindered their rapid implementation. Here, we present a 3D single-cell imaging technique, termed 3D digital rolling circle amplification (4DRCA), capable of the multiplexed and amplified simultaneous digital quantification of single-cell RNAs and proteins using standard fluorescence microscopy and off-the-shelf reagents. We generated spectrally distinguishable DNA amplicons from molecular markers through an integrative protocol combining single-cell RNA and protein assays and directly enumerated the amplicons by leveraging an open-source algorithm for 3D deconvolution with a custom-built automatic gating algorithm. With 4DRCA, we were able to simultaneously quantify surface protein markers and cytokine transcripts in T-lymphocytes. We also show that 4DRCA can distinguish BCR-ABL1 fusion transcript positive B-cell acute lymphoblastic leukemia cells with or without CD19 protein expression. The accessibility and extensibility of 4DRCA render it broadly applicable to other cell-based diagnostic workflows, enabling sensitive and accurate single-cell RNA and protein profiling.

Blinatumomab in Combination with Immune Checkpoint Inhibitors (ICIs) of PD-1 and CTLA-4 in Adult Patients with Relapsed/Refractory (R/R) CD19 Positive B-Cell Acute Lymphoblastic Leukemia (ALL): Results of a Phase I Study

Background: Blinatumomab (blina) improves outcomes in R/R CD19+ ALL compared to chemotherapy. However, the overall response rate to blina was 44%, and median overall survival (OS) is just 7.7 mos (Kantarjian. NEJM. 2017). Preclinical studies show increased PD-L1 expression on leukemic blasts potentially contributes to relapse after blina. The addition of PD-1 +/- CTLA-4 blockade to blina leads to increased in vitro T cell proliferation and enhanced cytotoxicity (Feucht. Oncotarget 2016). Thus, blockade of co-inhibitory pathways may enhance blina efficacy in vivo. We describe results of a multi-center phase I study combining blina with immune checkpoint inhibitors (ICIs) targeting PD-1 (nivolumab) +/- CTLA-4 (ipilimumab). Methods: In a dose-escalation study, we evaluated the safety, tolerability, and preliminary efficacy of blina with nivolumab (nivo) +/- ipilimumab (ipi) using a 3+3 design. Pts ³16 years-old with R/R CD19+ B-ALL or mixed phenotype acute leukemia (MPAL) were eligible. Pts ³60 years could be untreated. Table 1 presents the dose escalation schema. Expansion cohorts of 6 pts were planned at the maximum tolerated dose (MTD) for blina + nivo AND blina + nivo + ipi. Pts received up to 5 cycles of blina and 1 year of ICIs. Pts removed from the study during the blina lead-in (days 1-10) were replaced. Dose-limiting toxicities (DLTs) were defined as grade 3+ non-hematologic toxicities requiring the permanent discontinuation of treatment in the first 42 days. Primary endpoints were toxicities and MTD. Secondary endpoints included complete remission (CR), MRD-negativity at a sensitivity of 0.01%, duration of response and OS from treatment initiation. Results: Twenty-seven pts were enrolled to 3 dose levels (14 DLA1, 3 DLB1, and 10 DLB-1) from September 2017-December 2022. Six pts were replaced (4 prior to ICI dosing and 2 requiring subsequent therapy in the DLT window). The median age of enrolled pts was 55 (range 24-84), 14 were male (52%), and median baseline BM blasts were 60% (range 0.2-98%). Baseline characteristics are presented in Table 2. A single DLT (G4 infusion reaction and G3 hypotension) occurred among 6 pts at DLA1. Based on this safety and efficacy data, blina + nivo was expanded to include 6 additional pts without additional DLTs. There were 2 DLTs at DLB1 (G5 pneumonitis and G2 GVHD), which led to de-escalation to DLB-1, where there was 1 DLT (G3 delirium). Grade 2+ immune-related adverse events attributable to ICIs included pneumonitis (G2+G5), rash (G2+G3), transaminitis (G2+G3), colitis (G3), and hypothyroidism (G2). Grade 3+ adverse events attributable to blina included neutropenia (5-G4+3-G3), dysphasia (2-G3), weakness (G3), seizure (G4), and transaminitis (1-G4+4-G3). Among 22 pts evaluable for response, the CR rate was 68% (100% MRD-negative). Among 13 pts with >50% BM blasts at baseline, 62% achieved CR. Pts with B-myeloid MPAL (0/2) and a history of extramedullary disease (1/4) were less likely to respond. Nine responders subsequently relapsed including 3 with isolated extramedullary disease and 2 with CD19-negative disease. As shown in Figure 1, relapse-free survival (RFS) at 1 year was 27% (95% CI 10-46), while OS at 1 year was 63% (95% CI 38-79). Twelve pts underwent allogeneic blood or marrow transplant (alloBMT) following study treatment. At 1 year for alloBMT pts, RFS was 51% (95% CI 19-76) and OS was 61% (95% CI 26-83). Ongoing analyses of changes in T cell subpopulations, co-signaling molecule expression, and single cell RNA seq results will be presented. Conclusions: Combination therapy with blina and ICIs in R/R ALL is safe, feasible, and associated with a high MRD-negative response rate. Long-term survival was promising in comparison to prior results with blina monotherapy, especially following consolidation with alloBMT. A randomized trial of blina +/- nivolumab is needed to confirm the benefit of this combination.

A Phase II Study of Low-Intensity Chemotherapy (Mini-Hyper-CVD) and Ponatinib Followed By Blinatumomab and Ponatinib in Patients with Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia

Background Patients with Philadelphia chromosome (Ph)-positive B-cell acute lymphoblastic leukemia (ALL) treated with Hyper-CVAD and ponatinib achieve deep responses and long-term overall survival (OS). We aim to investigate if a reduced intensity regimen of mini-Hyper-CVD (mini-HCVD) with sequential blinatumomab (blina) in combination with ponatinib may further improve outcomes while mitigating the toxicity of intensive chemotherapy and the need for hematopoietic stem cell transplantation (HSCT). Methods Patients age ≥18 years with newly diagnosed (ND) or relapsed/refractory (R/R) Ph-positive ALL, or chronic myeloid leukemia in lymphoid blast phase (CML-LBP) were eligible. Other inclusion criteria included adequate liver, renal and cardiac function, and ECOG performance status ≤2. Patients with baseline central nervous system (CNS) involvement were not excluded. All patients had BCR::ABL1 transcripts and fluorescence in situ hybridization (FISH) for t(9;22) done at baseline. Morphological analysis of FISH patterns was performed in ND patients to identify if the BCR::ABL1 signal was observed in myeloid cells (e.g., segmented neutrophils). Four cycles (C) of mini-HCVD alternating with methotrexate (MTX) + cytarabine were followed by blina 28µg/d given for four weeks every six weeks during C5-8. Patients received ponatinib 30mg daily initially, with a dose reduction to 15mg daily once in complete molecular remission (CMR). CMR was defined as undetectable BCR::ABL1 with an assay sensitivity of 0.01%. Rituximab was given for CD20-positive disease. Maintenance ponatinib, vincristine and prednisone for 15 cycles with blina + ponatinib every three cycles was given, followed by ponatinib for at least five years. All patients without CNS disease received 12 intrathecal injections of MTX or cytarabine. Results 20 patients (12 ND, 4 R/R, 4 CML-LBP) were treated between November 2019 and May 2023. Baseline characteristics are shown in Table 1. One patient with CML-LBP had received prior dasatinib while in chronic phase. The predominant BCR::ABL1 transcript was p190 in 7 (58%) ND patients. All patients achieved a complete remission (CR). Among patients in the ND, R/R, and CML-LBP cohorts, CMR was achieved in 10/12 (83%), 3/4 (75%), and 4/4 (100%) patients, respectively. In the ND cohort, six (50%) patients achieved CMR after C1 and eight (67%) after C3. Five (42%) ND patients had documented BCR::ABL1 signal in myeloid cells by FISH. Four of them achieved CMR, after C1, C3, C4 and C3 maintenance respectively. With a median follow-up of 25 months (range, 2-42), the 2-year continuous remission duration (CRD) and OS rates were 93% and 83% for the entire cohort (Figure 1), and 90% and 82% in the ND cohort, respectively. In the ND cohort, one (8%) patient had isolated CNS relapse (during C4 of maintenance with blina and ponatinib), three (25%) patients died (two in CR due to COVID-19 and one of HSCT complications), and eight (67%) patients are in remission without HSCT. No patients relapsed in the R/R cohort; one patient underwent HSCT, one patient died in CR from MTX-associated disseminated necrotizing leukoencephalopathy, and two patients are in remission without HSCT. None of the CML-LBP relapsed; one patient underwent HSCT in CR. Ponatinib dose was reduced in two patients prior to obtaining CMR (one had pancreatitis, one had cardiomyopathy). One patient switched from ponatinib to dasatinib due to a pulmonary embolism in C2. No patients required dose modification of blina. The 60-day mortality rate was 0%. Conclusion In patients with Ph-positive ALL, the combination of mini-HCVD and ponatinib followed by sequential blina and ponatinib yielded excellent outcomes with durable remissions. The toxicity profile was favorable and HSCT was avoided in most patients with ND disease. Longer follow-up is needed to confirm the durability of responses.

Pediatric Patients with Acute Lymphoblastic Leukemia Treated with Blinatumomab in a Real-World Study

Introduction Pediatric B-cell acute lymphoblastic leukemia (B-ALL) involves chromosomal abnormalities and genetic alterations at an early stage of differentiation of lymphoid precursor cells. Most children (~around 80%) with B-ALL can achieve long-term survival with conventional chemotherapy but a sizable number of patients relapse or do not attain complete remission. Blinatumomab is a bispecific T-cell engager antibody designed to redirect CD3+ T cells to bind to CD19+ target cells. Although blinatumomab has been approved for the treatment of relapsed or refractory B-ALL, it has shown efficacy in newly diagnosed B-ALL also. Here, we studied the effect of blinatumomab in newly diagnosed B-ALL (including infantile B-ALL) and post-induction therapy measurable residual disease (MRD) positive B-ALL in a real-world study. Methods Pediatric patients with B-ALL including newly diagnosed infants (infantile type) or with MRD positivity during the induction remission phase, were enrolled. The patients received a 7-day pre-treatment VCP regimen consisting of intravenous infusions of cyclophosphamide 800 mg/m 2 on day 1, vindesine 3 mg/m 2 on day 1, prednisone 1-2 mg/kg on days 1 to 7 (VCP regimen), followed by 28 days of treatment with blinatumomab at 5µg/m 2/day on the first 1 to 7 days and 15 µg/m 2/day on the next 8 to 28 days. Four patients with economic burden received blinatumomab for 14 days: 5µg/m 2/day for days 1 to 4 and 15 µg/m 2/day from day 5 to 14, after pre-treatment with the VCP regimen. Bone marrow assessment of MRD was done on days 14 and 28. Results Between July 2022 and July 2023, 24 pediatric patients received VCP-blinatumomab. Among them, 11 (45.8%) patients had high-risk disease, and 5 (20.8%) had standard risk. The median age of the cohort was 8.5 years. Among the cohort, there was 1 patient with infantile B-ALL and 1 patient with Philadelphia chromosome-positive (Ph+)-ALL; besides 3 patients were TEL-AML positive, 3 patients were CRLF2 positive, 1 patient was E2A-PBX1 positive, 1 patient was SSBP2-CSF1R positive, and 1 patient was EVI1 positive. Blinatumomab was administered to 5 patients in the induction remission period, and for 2 patients, blinatumomab was administered in consolidation after inotuzumab ozogamicin (INO). While 18 patients were treated with blinatumomab for 28 days, 6 patients were treated with blinatumomab for 14 days. Four patients opted for a 14-day regimen due to financial reasons and 2 patients were transplanted with hematopoietic stem cell transplantation after 14 days of treatment with blinatumomab. All the treated patients achieved MRD negativity (100%). There were no ≥ grade 3 treatment-related toxicity and no deaths reported. Conclusion Our study results showed that a 100% MRD negativity rate was achieved in children with B-ALL after treatment with the blinatumomab consolidation following the chemotherapy and no significant safety concerns were observed. Blinatumomab consolidation therapy was also effective in patients pretreated with INO. Blinatumomab consolidation after induction therapy could be a new and effective strategy for the treatment of patients with newly diagnosed B-ALL.

A NUDT15 Genetic Polymorphism Study in Adult Acute Leukemia Patients Integrating Pharmacogenomics and Clinical Practice: A Single Centre Experience from South India

Background: Severe myelosuppression secondary to thiopurines such as 6-Mercaptopurine (6-MP) in patients with acute leukemia undergoing maintenance therapy is frequently attributed to inherited genetic polymorphisms of Thiopurine Methyltransferase (TPMT); however, this is rare in the Asian population. Nucleoside diphosphate-linked moiety X-type motif 15 (NUDT15) is also responsible for encoding critical enzymes involved in 6-MP metabolism. We aimed to determine the frequency of genetic polymorphisms of NUDT15 in the South Indian population and the impact of the omission of 6-MP from the treatment protocol of these patients. Methods: We retrospectively reviewed 17 patients diagnosed with acute leukemia between May 2018 and May 2020 and analyzed the prevalence of NUDT15 genetic polymorphisms in these patients. The NUDT15 mutation study (NUDT15 415C>T) used allele-specific Real-Time PCR in peripheral blood. 6-Mercaptopurine (6-MP) was excluded from the treatment regimen of patients with NUDT15 genetic polymorphisms and the impact of its exclusion was also studied. Results: Among the 17 patients for whom we cared, 10 were diagnosed with B-cell Acute Lymphoblastic Leukemia (B-ALL), three with T-cell Acute Lymphoblastic Leukemia (T-ALL), one with Mixed Phenotype Acute Leukemia (MPAL), and one with Acute Promyelocytic Leukemia (APML). Treatment records could not be retrieved for 2 patients. NUDT15 mutations were present in six patients (36%) (see fig1), of whom two had homozygous (33%) polymorphisms and four had heterozygous (67%) polymorphisms. In the heterozygous group, 2 were Ph. (Philadelphia chromosome) negative B-ALL; one was treated with BFM and the other with hyper-CVAD, one Ph. positive B-ALL was treated with BFM + Ponatinib, and one High-risk APML was treated with the APML 4 protocol. In the homozygous group, treatment details could not be retrieved for one case, and the other patient had T-ALL, which was treated with hyper-CVAD. 6-MP was omitted from the treatment protocol for all NUDT15 mutation-positive patients, both homozygous and heterozygous. Of these patients, two developed grade 1 myelosuppression, one developed grade 2 myelosuppression, one developed dyselectrolytemia, and one patient did not develop any toxicity. The incidence of severe or grade 3 and 4 myelosuppression in NUDT15 polymorphisms receiving 6MP can be as high as 50% (Khaeso K et.al Front Pharmacol. 2021). In comparison, none of our patients developed grade 3 or 4 myelosuppression. Overall, treatment-related adverse events included grade 1-2 myelosuppression (n=6), grade 1-2 hepatotoxicity (n=1), deep vein thrombosis (n=2), and sepsis (n=2). Five of the 6 patients with NUDT15 mutations achieved complete remission (CR). Conclusion: The prevalence of NUDT15 polymorphisms was high in our study population. Based on a meta-analysis, the prevalence of NUDT15 in the South Indian population was 16.5%, and in patients with adverse effects, the pooled prevalence of NUDT15 polymorphisms was 49.51% (Anuraag Jena et.al. Expert Review of Clinical Pharmacology 2021). Based on our results, although limited by the small number of cases, we suggest that pre-emptive testing to detect these polymorphisms should be undertaken in all adult acute leukemia patients of South Indian origin, given their high prevalence in this population. The omission of 6-MP from treatment protocols can help prevent severe myelosuppression and treatment interruption or discontinuation, which in turn can improve treatment outcomes.

Novel strategies to prevent and overcome relapse after allogeneic hematopoietic cell transplantation in acute lymphoblastic leukemia.

The outcome of B-cell acute lymphoblastic leukemia (B-ALL) has improved over time with the incorporation of multi-agent chemotherapy in the treatment landscape as well as the recent approval of immunotherapeutic agents allowing a larger proportion of patients to undergo allogeneic hematopoietic cell transplantation (allo-HCT) which is still considered a potential curative approach. However, relapse post-transplant is still occurring and constitutes a common cause of treatment failure in B-ALL. The present review aims to discuss the novel strategies and therapies used to prevent and overcome relapse post allo-HCT in patients with ALL, focusing on the role of tyrosine kinase inhibitors in Philadelphia chromosome positive B-ALL, the role of innovative agents such as blinatumomab and inotuzumab ozogamicin, and finally the role of cellular therapy.

Ph-Positive B-Cell Acute Lymphoblastic Leukemia Occurring after Receipt of Bivalent SARS-CoV-2 mRNA Vaccine Booster: A Case Report

The coronavirus disease 2019 (COVID-19) pandemic is a universal emergency public health issue. A large proportion of the world's population has had several spike antigen exposures to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and/or COVID-19 vaccinations in a relatively short-term period. Although sporadic hematopoietic adverse events after COVID-19 vaccine inoculation were reported, there is currently no sufficient evidence correlating anti-spike protein immune responses and hematopoietic adverse events of vaccinations. We reported the first case of Ph-positive B-cell acute lymphoblastic leukemia (ALL) occurring after a bivalent mRNA COVID-19 vaccine inoculation. The otherwise healthy 43-year-old female patient had a total of six spike antigen exposures in the past 1.5 years. Informative pre-vaccine tests and bone marrow study results were provided. Although the causal relationship between bivalent vaccinations and the subsequent development of Ph-positive B-cell ALL cannot be determined in the case report, we propose that anti-spike protein immune responses could be a trigger for leukemia. Clinicians must investigate the hematopoietic adverse events closely after COVID-19 vaccinations. Further pre-clinical studies to investigate the safety of bivalent mRNA COVID-19 vaccine are required.

Treatment de-escalation in Philadelphia chromosome-positive B-cell acute lymphoblastic leukemia: the emerging role of chemotherapy-free regimens.

The management of Philadelphia chromosome-positive (Ph-positive) acute lymphoblastic leukemia (ALL) has witnessed major progress over the past two decades. Initially, the incorporation of the first-generation BCR::ABL1 tyrosine kinase inhibitor (TKI) imatinib into intensive chemotherapy regimens improved outcomes compared with chemotherapy alone. The combinations of chemotherapy with second- or third-generation TKIs further improved outcomes, with higher rates of complete molecular remission (CMR) and superior survival. The combination of ponatinib plus chemotherapy resulted in durable remissions and prolonged long-term survival, even in patients who did not receive allogeneic stem cell transplantation (SCT). The promising results seen with later-generation TKIs have caused many to re-evaluate the role of allogeneic SCT for patients who achieve CMR with potent TKI regimens. Recently, the chemotherapy-free combinations of blinatumomab plus TKIs were shown to be safe and effective in newly diagnosed Ph-positive ALL, sparing patients the toxicities associated with intensive chemotherapy. In particular, encouraging early results have been seen with the combination of blinatumomab plus ponatinib, suggesting that this regimen may represent a chemotherapy-free and SCT-sparing strategy for patients with Ph-positive ALL. Herein, we discuss the current evidence for frontline therapies of Ph-positive ALL, the treatment de-escalation strategies over time, and the role of allogeneic SCT in view of the emergence of newer chemotherapy-free regimens using potent TKIs.

Minimal Residual Disease Negativity after Blinatumomab Is Predictive of Survival in B-Cell Acute Lymphoblastic Leukemia: Data from a Real-Life Study

Introduction The novel pediatric-like and TKI-based induction regimens induce up to 90 % of complete hematologic response in, respectively, Ph'-negative and Ph'-positive B-Cell Acute Lymphoblastic Leukemia (B-ALL). Minimal residual disease (MRD) strongly correlates with relapse and clearance of MRD is the goal of treatment. Blinatumomab is a bispecific T-cell engager that redirects T-Cells to kill CD19+ cells. Data from clinical trials show that the MRD-positive patients responding to Blinatumomab achieve a better survival than the non-responsive. This retrospective study from real-life demonstrates a superior outcome for MRD-responsive patients to blinatumomab over non-responsive patients. Patients and methods Data from adults treated with blinatumomab in six centers were analyzed to identify factors correlated to survival. Each cycle of blinatumomab was administered in 4 weeks at 15 mg/m2/day by continuous infusion followed by a 2-week interval. Intrathecal prophylaxis with ARA-C, Methotrexate and Dexamethasone was performed between cycles. Twenty-nine (87 %) patients received levetiracetam for seizure-prophylaxis. MRD was measured after each cycle by RT-qPCR with a sensitivity of 10-4 for clonal IgH and for BCR-ABL. As MRD response was considered clonal IgH or BCR-ABL < 10-4. Relapse-free survival (RFS) and overall survival (OS) were estimated by the Kaplan-Meier analysis and compared by the log-rank across the sub-groups using 95 % confidence intervals. The significant variables were compared in multivariate analysis by the log-logistic regression model. Toxicity was graded according to CTCAEs v.4 scale. Results From January 2016 to February 2021 34 B-ALL patients received Blinatumomab. The median age was 37 (18-72). Male to female ratio was 14/20. B-ALL was Ph'+ in 9 and Ph'- in 25 patients, respectively. Indications to blinatumomab were, respectively, relapsed/refractory B-ALL in 19 and MRD-positive in 15 patients. SNC disease was negative before blinatumomab in all patients. Blinatumomab was administered, respectively, as 2nd line in 26 and as > 2nd line of therapy in 8 patients. Overall, 24 patients received hematopoietic transplantation (HCT): 10 before and 14 after blinatumomab, respectively. The cycles of blinatumomab were 1, 2, 3 and 4, respectively, in 10, 13, 5, and 5 patients. The response to blinatumomab was, respectively, complete remission without MRD in 17 (50 %), complete remission with MRD in 8 (23 %), refractory in 4 (12 %) and extramedullary progression in 2 (6 %) patients. Three patients (9 %) had to suspend treatment in 1st cycle because of grade III-IV neuro-toxicity. The response was obtained after 1 and 2 cycles in 18 (72 %) and 7 patients (28 %), respectively. Among the MRD-responsive, MRD-negativity was obtained after 1 and 2 cycles in 16 (93 %) and 1 (7 %) patient, respectively. At a median follow-up of 16 months (1-47) 15 patients (44 %) had relapsed, 15 (44 %) were alive and in complete remission and 4 (12 %) died of transplant-related mortality. The median RFS was 12.5 months (1-39). The median OS was 15.5 months (1-46). The median RFS was 21 vs 4.4 months among MRD-responsive and non-responsive patients, respectively (p = .0004). The median OS was 27 vs 8.7 months among MRD-responsive and non-responsive patients, respectively (p = .008). Apart from MRD-response, the other variables significant for RFS were: blinatumomab as ≤ 2nd line (p = .0008), blinatumomab administered pre-HCT (p = .002) and MRD as an indication to treatment (p = .001). Apart from MRD-response, the other variable significant for OS was MRD as an indication (p = .01). By multivariate analysis only the MRD-response resulted significant for RFS (p = .0009) and OS (p = .02). MRD-response resulted significantly for RFS and OS also by censoring at HCT (p < .0001 and .005, respectively) [Figure 1]. Clinically significant toxicity was: grade II cytokine-release syndrome in 2 patients, grade III and IV neuro-toxicity in 2 and 1 patient, respectively. Overall, the percentage of patients experiencing grade III-IV neuro-toxicity, which occurred in 1st cycle, was 9 %. Conclusion This retrospective study in adult B-ALL Ph'- and Ph'+ patients, confirms the ability of blinatumomab to reach the MRD-negativity in a substantial proportion of patients. MRD-responsive gain a significant survival advantage over non-responsive patients. This advantage was observed both for transplanted and non-transplanted patients. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

A Phase II Study of Inotuzumab Ozogamicin for the Treatment of Measurable Residual Disease-Positive B-Cell Acute Lymphoblastic Leukemia

Background: Persistence or re-emergence of measurable residual disease (MRD) after remission induction therapy in B-cell acute lymphoblastic leukemia (B-ALL) is strongly associated with shorter relapse-free survival (RFS) and overall survival (OS). Inotuzumab ozogamicin (INO) is an anti-CD22 antibody-drug conjugate with the potential to eradicate MRD in patients (pts) with B-ALL, including in pts with prior exposure to blinatumomab. Methods: This is a single-arm phase II trial of pts with B-ALL in complete remission (CR) who did not achieve MRD negativity (MRD-ve) or had MRD-positive (MRD+ve) relapse after at least 3 months (mos) from the start of frontline therapy or 1 month from the start of any salvage therapy. Eligibility was defined by MRD+ve at ≥ 0.01% by multiparametric flow cytometry (MFC) for Philadelphia chromosome (Ph) negative (Ph-) B-ALL and ≥ 0.01% by MFC and/or BCR::ABL1 transcripts for Ph positive (Ph+) B-ALL. MRD-ve was defined as undetectable MRD by MFC at a minimum sensitivity of 10-4 for Ph- B-ALL and undetectable MRD by both MFC and BCR::ABL1 transcripts at 10-4 for Ph+ B-ALL. For pts with p210 BCR::ABL1 transcript, the international scale (IS) was used for reporting. INO was administered at a dose of 0.6 mg/m2 on D1 and 0.3 mg/m2 on D8 of cycle 1 and 0.3 mg/m2 on D1 and D8 of cycles 2-6 (cycles given every 21-28 days). Pts received ursodiol prophylaxis while on INO. Pts with Ph+ ALL could receive a concomitant BCR::ABL1 tyrosine kinase inhibitor (TKI). Results: Between 11/2018 and 6/2022, 27 pts with MRD+ve B-ALL were treated. The median age was 44 years (range, 19-70). Seventeen pts (63%) had Ph+ ALL (12 pts with p190 transcript and 5 pts with p210 transcript), 15 of whom received concurrent ponatinib and 2 dasatinib. Ten pts were Ph- (including 3 with Ph-like ALL). Twenty pts (74%) were in CR1, and 7 pts (26%) were in ≥ CR2 (4 in CR2, 2 in CR3 and 1 in CR4). Fourteen pts (52%) had received prior blinatumomab and 5 pts (18%) had prior stem cell transplantation (SCT). The median level of BCR::ABL1 by PCR in pts with Ph+ ALL was 0.21% (range, 0-18.9%) and median level by MFC in pts with Ph- ALL was 0.21% (range, 0.05-1.24%). Seven pts with Ph+ ALL were MRD+ve by MFC at a median of 0.04%, and 1 pt with Ph+ B-ALL was MRD+ve by MFC (1.15%%) but negative by PCR. Eighteen pts (67%) responded and became MRD-ve, 16 after cycle 1 and 2 after cycle 2. In the Ph+ group, 10 pts (59%) responded; another 3 of 5 pts who had >0.1% BCR::ABL1 transcripts at enrollment attained major molecular response as best response. Eight of 10 (80%) pts with Ph- ALL responded. The median number of cycles was 3 (range, 1-6). Eleven of 13 pts (85%) without prior blinatumomab exposure became MRD-ve compared with 7/14 (50%) pts with prior blinatumomab exposure (p=0.1). At a median follow up of 18 months (mos) (range, 1.1- 35 mos), 14 of the 18-responding pts (78%) are in ongoing MRD-ve CR. The median RFS and OS of the pts were not reached. The estimated 18-mos RFS and OS were 56% and 65%, respectively, for the whole group. 18-mos OS was 73% and 60% for responders and non-responders, respectively (p=0.7). Amongst the 18 responders, 5 pts were consolidated with SCT after a median of 3 cycles (range, 1-3) of INO, all in MRD-ve CR prior to SCT. Four (22%) responders had morphological relapse (including one relapse after SCT and one isolated CNS relapse). One pt died in MRD-ve CR due to SCT-related complications. Survival was similar between pts with Ph+ ALL vs. Ph- ALL (p=0.41), pts in CR1 vs. ≥ CR2 (p=0.23) and those with prior blinatumomab exposure vs. no prior exposure (p=40). INO was overall well-tolerated with no grade 4 non-hematological toxicities. Two pts (7%) developed veno-occlusive disease (VOD); both had Ph+ ALL and were on concurrent ponatinib. One pt developed VOD (diagnosed radiologically) 1 month after ponatinib dose of 15mg/day) and another pt developed VOD (diagnosed by liver biopsy) during cycle 5 (cumulative INO dose of 3.3 mg/m2, ponatinib dose of 15mg/day). The overall 60-day mortality was 0%. Conclusion: Lower doses of fractionated INO is a well-tolerated option for MRD eradication in pts with Ph+ or Ph- B-ALL, including in those with prior blinatumomab exposure or SCT. This approach can also facilitate consolidative SCT in these pts. The therapy is well tolerated, but pts should be monitored for development of VOD of the liver, though the absolute risks remain low. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Gimema ALL2418: Interim Analysis of a Phase Iia Study of Feasibility and Effectiveness of Inotuzumab Ozogamicin in Adult Patients with B-Cell Acute Lymphoblastic Leukemia with Positive Minimal Residual Disease before Any Hematopoietic Stem Cell Transplantation

Background: Persistence of minimal residual disease (MRD) is associated with a high rate of treatment failure, relapse, and death in B-cell acute lymphoblastic leukemia (B-ALL). Particularly, patients who remain MRD positive before an allogeneic hematopoietic stem cell transplant (HSCT) have an expected disease-related death rate due to the disease of about 60%. The T cell-engager CD19-directed therapy blinatumomab demonstrated considerable efficacy in this setting, however resistant or unsuitable patients have no alternative therapy. Inotuzumab Ozogamicin (IO) is a CD22-directed antibody-drug conjugate with remarkable efficacy in B-ALL with overt disease. Furthermore, IO does not need a high effective immune system to exert activity. Methods: In this multicenter phase 2 trial (NCT03610438), we are investigating the efficacy of IO in obtaining MRD negativity in two cohorts of 38 Ph+ and 38 Ph- B-ALL patients. IO was administered at the dose of 0.5 mg/sqm on days 1, 8, and 15 of a 28-days cycle. Patients who did not obtain MRD negativity after the 1st IO cycle had the option to receive the 2nd IO cycle maintaining the same dosage. Responding Ph- patients received short-term maintenance with low-dose chemotherapy (alternating vincristine, cyclophosphamide, prednisone, methotrexate, and 6-mercaptopurine), responding PH+ patients received tyrosine kinase inhibitor (TKI) for up to 12 weeks, allowing proper IO washout before HSCT. HSCT ineligible patients entered into low-dose chemotherapy or TKI maintenance for up to 2 years. For the primary endpoint, MRD was centrally assessed at baseline, after course 1, after course 2, and eventually before transplant with high sensitive molecular methods for BCR-ABL1 or V(d)J fusion transcripts. Here, we present the results of an unplanned interim analysis that was generated to evaluate the continuation of the study considering the slow accrual due to the Sars-COV2 pandemic. Results: To date, 51 patients underwent screening procedures, and 43 were considered eligible. We report data from the first 39 patients treated in the study. Nineteen out of 39 patients had Ph- B-ALL and 20/39 Ph+ B-ALL. Eighteen out of 39 (46%) patients were male. The median age was 55 years (22-84), 15/39 patients (38%) were older than 65 years. Demographics were comparable between Ph+ and Ph- patients. Within Ph+, ALL 39% of patients harbored p190 and 61% p210 fusion transcript. Within Ph- B-ALL, 1 patient harbored ALL1/AF4 and 1 patient harbored ALL1/ENL fusion transcript. Most of the patients received 1 (16/39, 42%) or 2 (19/39, 50%) previous lines of therapy; 5 patients (13%) were resistant to blinatumomab, and all of them had Ph- B-ALL. Twelve out of 19 (63%) Ph- B-ALL patients received only 1 IO cycle, 7/19 (37%) received 2 cycles; 5/20(25%) Ph+ B-ALL received only 1 IO cycle, and 15/20 (75%) received 2 cycles. To date, central MRD monitoring is available for 20 patients (12 Ph- and 8 Ph+ B-ALL, ongoing for the remaining cases). Overall, MRD negativity was obtained in 7/20 patients (35%); Particularly, in Ph- B-ALL cohort 5/12 (42%) patients achieved MRD negativity, 4/12 (38%) achieved disease reduction at low level MRD positivity (<10-4); in Ph+ B-ALL cohort, 2/8 (25%) patients achieved MRD negativity. One out of 5 (20%) blinatumomab pre-treated patients obtained MRD negative response. IO was an effective bridge to HSCT for 10/39 patients (26%; in patients <65 years old, 9/24 patients, 37%); Specifically, all 7 patients who obtained MRD negativity after IO, a patient with low-positive MRD and 2 patients with non yet available MRD data were bridged to HSCT. Accordingly, with the caveat of a short median follow-up (2.8 months, range 0.6-20.0 months), overall survival in the study population seems promising (figure 1, median OS not reached). Overall, adverse events collected during the study were limited in number and grading. Also, myelotoxicity was manageable. Out of 39 patients, we documented 1 veno-occlusive disease (2.5%) that occurred within 20 days from the last IO dose and before any HSCT. Conclusions: IO administration demonstrated activity with a good safety profile in the setting of MRD positive B-ALL, including blinatumomab resistant patients. Importantly, IO was capable to bridge 37% of eligible patients to HSCT, augmenting the chance to achieve a cure. The continuation of the study will deliver mature efficacy and survival data for a proper evaluation of this promising strategy. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Pro-Active 4SCAR2.0 Therapy with NGS-MRD Disease Monitoring in High-Risk B Cell Leukemia Management

BACKGROUND: Allogeneic hematopoietic stem cell transplantation (HCT) is a standard treatment for high-risk relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL). However, about 30-40% of patients still relapse after HCT. Chimeric antigen receptor-modified T cell (CAR-T) therapy holds great promise as a salvage approach. Although CD19-targeted CAR-Ts have demonstrated a rapid and significant anti-tumor effect in patients with B-cell malignancies, many still suffer disease relapse due to the decrease or loss of CD19 antigen. Therefore, novel curative approaches are needed. PURPOSE: The aim of this study is to determine the best timing for applying CAR-T therapy in high-risk B-ALL patients based on high-sensitivity analysis of tumor cells by next-generation sequencing (NGS) detecting minimal residual disease (MRD). An innovative CAR-T therapy concept, CAR2.0, has been proposed, which uses multi-antigen-targeted CAR-Ts to prevent antigen escape and prolong remission. Based on NGS-MRD detection, patients with potential tumor relapse can be identified early and managed accordingly. On the other hand, if extended negative NGS-MRD is found, the patient is deemed at low risk and no further treatment is needed. The study proposes to treat high-risk B-ALL patients in the first remission period with CAR2.0 followed by continued disease monitoring by NGS-MRD to avoid HCT. METHODS: B-ALL patients who have high tumor burden and high-risk genetic indication is enrolled with the understanding that CAR-T therapy will be applied in the first remission and disease will be continuously monitored by NGS-MRD. The tumor cells from initial diagnosis will be analyzed for target antigens by immunostaining and to detect clonally rearranged immunoglobulin gene sequences by NGS-MRD with sensitivity ≤10-6. Patients will receive 4SCAR19 (CD19scFv-CD28/CD27/CD3ζ-iCasp9) therapy in the first remission and will be followed up for CAR-Ts, B cells and IgG/IgA/IgM in the blood, and bi-monthly NGS-MRD for residual tumor cells in the bone marrow (BM). A booster CAR-T treatment targeting additional tumor antigen such as CD22 will be applied 2 months later. A consolidation CAR-T treatment based on known target antigens will be applied 6 months after the first CAR-T infusion. The cyclophosphamide/fludarabine chemo-conditioning will be included prior to the first CAR-T treatment only. The CAR-T infusion dose is 1-5x106 CAR-Ts/kg. The quality of apheresis cells, efficiency of gene transfer, T cell proliferation, CAR-T infusion dose and blood CAR copies are quantitatively documented. The end point for this study is the establishment of NGS-MRD negativity for 1 year, with continued follow-up for 5 years. RESULTS: A 20 years old female was diagnosed with BCR/ABL1 P190 positive B-ALL, with 82.52% tumor blasts in the BM. NGS identified two high-frequency IgH clones at 66.29% and 30.41%. The patient received induction chemotherapy (VTCP, CAM, VP+MTX) combined with TKI therapy (Nilotinib) and achieved complete remission (CR) after the first round of treatment based on both flow cytometry and NGS MRD analyses. During the fourth round of chemotherapy (Methotrexate-Cytarabine-Dexamethasone), the patient suffered severe oral and intestinal mucositis, along with kidney and liver toxicity and required week-long dialysis. A decision was made to stop chemotherapy and start the first 4SCAR19 therapy of 3.53x106 CAR-Ts/kg, while maintaining the TKI therapy. The CAR-T cells in blood, the B cell count and Ig levels were monitored, and a booster CD22/CD19 dual CAR-Ts (4SCAR2219) was given at a dose of 3.35 x106 CAR-Ts/kg on day 96 (see figure). Consistent with 4SCART safety profile, the patient experienced no greater than grade 1 CRS. NGS-MRD detection of tumor cell clones remained negative on day 96 after the first CAR-T infusion and at 6 months into the remission. In summary, the 4SCAR2.0 therapy regimen appeared safe and effective in the innovative NGS-MRD/4SCAR2.0 B-ALL study regimen with in vivo persistency for more than three months. The simultaneous expansion of CD19 mono-specific and CD22/CD19 bi-specific CAR-Ts supports a stable maintenance treatment with good life quality as compared with conventional chemotherapy. CONCLUSIONS: The combination of 4SCAR2.0 with NGS-MRD detection of tumor clones in the management of high-risk B-ALL appears to be safe and may be a logical option for patients not elected for HCT therapy. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

First-Line Consolidation Therapy with CD19/CD22 Bispecific CAR-T Cells for MRD Positive B-ALL Maybe Feasible

Measurable residual disease (MRD) persistence after induction or early intensive therapy has proved to be the strongest independent prognostic indicator for B-cell acute lymphoblastic leukemia (B-ALL). Here we presented a phase I study to evaluate the safety and efficacy of CD19/CD22 bispecific targeted chimeric antigen receptor (CAR) T-cells for MRD positive B-ALL, especially as first-line consolidation therapy for primary patients. The primary objective was to assess the safety and the secondary objective was for its efficacy. The most common adverse events (AEs) were hematologic related, including anemia of 93.3%(14/15), leukopenia of 100% (15/15), decreased neutrophil count of 100% (15/15), and decreased lymphocyte count of 100% (15/15).Cytokine release syndrome (CRS) occurred in 4 patients (26.7%) and all of them were grade 1 or 2. One patient (6.7%) developed delayed later neurotoxicity and related symptoms were obviously alleviated after treatments with prednisone. The overall MRD response rate was 100% at day 28. With a median follow-up of 15.5 months (range, 2.5-33), the median RFS and OS were not reached. For all patients, the 2-year RFS and OS were 77% (95% CI, 55-99) and 86% (95% CI, 68-104), respectively, while for patients in first-line consolidation group, the 2-year RFS and OS 77.8% (95% CI, 51-105) and 80.8% (95% CI, 57-105), respectively. The results suggested that CD19/CD22 bispecific CAR-T cells as first-line consolidation therapy might be feasible for MRD positive patients. This trial was registered at clinicaltrials.org (NCT: 03919526).

Anlotinib exerts potent antileukemic activities in Ph chromosome negative and positive B-cell acute lymphoblastic leukemia via perturbation of PI3K/AKT/mTOR pathway

ObjectivesDespite advances in the development of novel targeted therapies, the need for B-ALL alternative treatments has not been met. Anlotinib could blunt the proangiogenic activity of VEGFR, PDGFR, and FGFR, and has shown strong antitumor activities across multiple tumors. However, anlotinib cytotoxicity against B-ALL has not ever been evaluated, thus prompting us to initiate this study. MethodsExpression2Kinases program was used to identify potential treatment targets. Cell viability and apoptosis were determined by CCK-8 and Annexin V/PI staining kit, respectively. qRT-PCR and Western blotting were utilized to investigate the molecular mechanisms. In vivo antileukemia activity of Anlotinib was evaluated in a Ph+ B-ALL patient-Derived Xenograft (PDX) model. ResultsCompared with treatment-naive B-ALL cases, RR B-ALL patients had higher activities in the VEGF/VEGFR signaling and the PI3K/AKT/mTOR pathway. Exposure of Ph− and Ph+ B-ALL cells to anlotinib resulted in significant cell viability reduction, apoptosis enhancement, and cell cycle arrest at G2/M phase. Importantly, anlotinib treatment led to remarkably decreased leukemia burdens and extended the survival period in a Ph+ B-ALL PDX model. Blockade of the role of the proangiogenic mediators, comprising VEGFR2, PDGFR-beta, and FGFR3, played a critical role in the cytotoxicity of anlotinib against Ph− and Ph+ B-ALL. Moreover, anlotinib dampened the activity of PI3K/AKT/mTOR pathway that resides in the convergence of the three mentioned proangiogenic signals. ConclusionThis work provides impressive preclinical evidence of anlotinib against Ph− and Ph+ B-ALL and raises a rationale for future clinical evaluation of this drug in the management of Ph− and Ph+ B-ALL.

P368: A PHASE II STUDY OF INOTUZUMAB OZOGAMICIN FOR THE TREATMENT OF MEASURABLE RESIDUAL DISEASE-POSITIVE B-CELL ACUTE LYMPHOBLASTIC LEUKEMIA

Background: Persistence or re-emergence of measurable residual disease (MRD) in B-cell acute lymphoblastic leukemia (B-ALL) is strongly associated with shorter relapse-free survival. Inotuzumab ozogamicin (INO) is an anti-CD22 antibody-drug conjugate with the potential to eradicate MRD in B-ALL. Aims: We aimed to evaluate the efficacy of INO in clearing MRD in patients (pts) with persistent or recurrent MRD positivity after treatment with conventional chemotherapy. Methods: This is a single arm phase II trial of pts with B-ALL in complete remission (CR) who did not achieve MRD negativity (MRD-ve) or had MRD-positive (MRD+ve) relapse after at least 3 months (mos) from the start of frontline therapy (i.e. CR1) or 1 month from the start of any salvage therapy (i.e. ≥ CR2). Eligibility was defined by MRD+ve at ≥ 0.01%. MRD-ve was defined as undetectable MRD by flow cytometry at a minimum sensitivity of 10-4 for Philadelphia (Ph) negative (Ph-) B-ALL and undetectable MRD by both flow and PCR at 10-4 for Ph positive (Ph+) B-ALL. INO was given at a dose of 0.6 mg/m2 on D1 and 0.3 mg/m2 on D8 of C1 and 0.3 mg/m2 on D1 and 8 of subsequent cycles (up to 6 total cycles, given every 21-28 days) along with ursodiol prophylaxis. Pts with Ph+ ALL received concomitant TKI, the choice of which was decided by the treating physician. Results: Between 11/2018 and 1/2022, 20 pts with MRD+ve B-ALL, with a median age of 40 years (range, 19-68) were treated. Twelve pts (60%) had Ph+ B-ALL, 11 of whom received concurrent ponatinib and 1 dasatinib. Eight pts were Ph- (including 3 Ph-like ALL). Fourteen pts (70%) were in CR1, and 6 pts (30%) were in ≥ CR2 (3 in CR2, 2 in CR3 and 1 in CR4). Eleven pts (55%) had received prior blinatumomab (blina) and 4 pts (20%) had prior stem cell transplantation (SCT). The median BCR-ABL1 level in Ph+ B-ALL was 0.58% (range, 0.001-17.5%) and median MRD level by flow cytometry in Ph- B-ALL was 0.2% (range, 0.05-1.24%). Twelve pts (60%) became MRD-ve (responders), 10 after cycle 1 and 2 after cycle 2. In the Ph+ group, 6 pts (50%) responded; another 3 pts attained MMR as best response. Six of 8 (75%) Ph- pts responded. The median number of cycles were 3 (range, 1-6). Seven of 9 pts (78%) without prior blina exposure became MRD-ve, compared with 5/11 (45%) pts with prior blina exposure (p=0.22). Patient disposition is shown in Fig. 1A. Amongst the 12 responders, 5 pts were consolidated with ASCT after a median of 3 cycles (range, 1-3) of INO, all in MRD-ve CR pre-ASCT. Three responders (25%) relapsed (including 1 relapse after ASCT). At a median follow-up of 17 mos, 15 pts (75%) are alive, 8 of whom are in continued MRD-ve CR. The estimated 18 mos RFS and OS were 63% and 73% respectively, for the whole group (Fig. 1B), and the 18 mos OS was 87% and 55% for responders and non-responders, respectively. Outcomes were similar between pts with Ph+ ALL vs. Ph- ALL, prior blina exposure vs. no prior exposure, and pts in CR1 vs. ≥ CR2. INO was overall well-tolerated with no grade 4 non-hematological toxicities. Grade 3 non-hematological toxicities included elevated transaminases in 1 pt and veno-occlusive disease in 1 pt without history of prior ASCT. Ten pts (50%) had grade 3-4 hematological toxicities (primarily neutropenia). Image:Summary/Conclusion: Low-dose, fractionated INO is a well-tolerated option for MRD eradication in Ph+ and Ph- B-ALL pts, including in those with prior blina exposure.

The clinical outcomes and genomic landscapes of acute lymphoblastic leukemia patients with E2A-PBX1: A 10-year retrospective study.

The clinical outcomes and genomic features of E2A-PBX1 (TCF3-PBX1)-positive B-cell acute lymphoblastic leukemia (B-ALL) patients remain unclear. A total of 137 patients carrying E2A-PBX1 among 3164 B-ALL patients between 2009 and 2019 were retrospectively analyzed. The 5-year overall survival (OS) and disease-free survival (DFS) rates of the whole cohort were 68.6% and 61.0%, respectively. Age [DFS, p=0.037; cumulative incidence of relapse (CIR), p=0.005] and the level of minimal residual disease (MRD) after induction chemotherapy (OS, p=0.020; DFS, p=0.002; CIR, p=0.006) were independent risk factors. In adolescents/adults, allogeneic hematopoietic stem cell transplantation (allo-HSCT) at first complete remission (CR1) significantly improved the 5-year prognosis (OS, p < 0.001; DFS, p < 0.001; CIR, p < 0.001). Haploidentical HSCT decreased the CIR compared with human leukocyte antigen-matched HSCT in adolescents/adults (p=0.017). Mutations in PBX1, PAX5, CTCF and SETD2, amplification of AKT3, and deletion of CDKN2A/B were common in the total cohort, while transcriptome differences were found in the cell cycle, nerve growth factor (NGF) signaling pathway and transcriptional regulation by TP53 between adolescents/adults and children. Patients with multiple subclones at diagnosis tended to have unfavorable 3-year prognoses (DFS, p=0.010; CIR, p=0.021). Leukemia clones with DNA repair gene mutations showed aggressive and treatment-refractory phenotypes in this subtype of ALL. Our study indicated that age, the level of MRD and DNA repair gene mutations were associated with E2A-PBX1-positive B-ALL outcomes. Allo-HSCT, especially haploidentical HSCT, could improve the prognosis of adolescent/adult patients.