Morphologic Complete Remission Research Articles

Efficacy of venetoclax-based induction regimen in newly diagnosed pediatric acute myeloid leukemia

Objective: To explore the efficacy of venetoclax-based induction regimen for children with newly diagnosed acute myeloid leukemia (AML). Methods: Children with newly diagnosed AML in Beijing Children's Hospital Affiliated to Capital Medical University and Baoding Hospital Affliliated to Capital Medical University from November 2019 and December 2023 were prospectively included. The patients were divided into DAH group (daunorubicin, cytarabine and homoharringtonine) and VAH group (venetoclax, cytarabine and homoharringtonine) according to induction regimen. The clinical data of the children were collected, the clinical characteristics and induced remission rate between the two groups were compared, and multivariate logistic regression was used to analyze the related factors affecting the induced remission rate. Results: A total of 135 patients were enrolled, including 96 cases in the DAH group (54 males and 42 females), aged [M (Q1, Q3)] 6.4 (3.9, 11.6) years and 39 cases in the VAH group (26 males and 13 females), aged 8.0 (6.2, 13.2) years. Among patients initially diagnosed with low-medium risk AML, the morphologic complete remission rates were 94.7% (18/19) in the VAH group and 84.4% (38/45) in the DAH group, respectively, and the negativity conversion rates of minirnal residual disease (MRD) were 57.9% (11/19) and 46.7% (21/45), respectively, with no statistically difference (all P>0.05). Among patients initially diagnoised with high-risk AML, the morphologic complete remission rates in the VAH group was higher than that in the DAH group [95.0% (19/20) vs 70.6% (36/51), P=0.027], and negativity conversion rates of MRD were 45.0% (9/20) and 33.3% (17/51), respectively, with no statistically difference (P=0.359). The induction regimen (venetoclax, cytarabine and homoharringtonin) was beneficial to morphological remission (OR=0.126, 95%CI: 0.025-0.629). FLT3 mutation was not conducive to morphological remission (OR=5.832, 95%CI: 1.778-19.124) and negative MRD (OR=4.166, 95%CI: 1.396-12.433). Conclusion: Venetoclax-based induction regimen is more effective than traditional chemotherapy regimen for newly diagnosed pediatric AML.

Memory T-cell enriched haploidentical transplantation with NK cell addback results in promising long-term outcomes: a phase II trial

BackgroundRelapse remains a challenge after transplantation in pediatric patients with hematological malignancies. Myeloablative regimens used for disease control are associated with acute and long-term adverse effects. We used a CD45RA-depleted haploidentical graft for adoptive transfer of memory T cells combined with NK-cell addback and hypothesized that maximizing the graft-versus-leukemia (GVL) effect might allow for reduction in intensity of conditioning regimen.MethodsIn this phase II clinical trial (NCT01807611), 72 patients with hematological malignancies (complete remission (CR)1: 25, ≥ CR2: 28, refractory disease: 19) received haploidentical CD34 + enriched and CD45RA-depleted hematopoietic progenitor cell grafts followed by NK-cell infusion. Conditioning included fludarabine, thiotepa, melphalan, cyclophosphamide, total lymphoid irradiation, and graft-versus-host disease (GVHD) prophylaxis consisted of a short-course sirolimus or mycophenolate mofetil without serotherapy.ResultsThe 3-year overall survival (OS) and event-free-survival (EFS) for patients in CR1 were 92% (95% CI:72–98) and 88% (95% CI: 67–96); ≥ CR2 were 81% (95% CI: 61–92) and 68% (95% CI: 47–82) and refractory disease were 32% (95% CI: 11–54) and 20% (95% CI: 6–40). The 3-year EFS for all patients in morphological CR was 77% (95% CI: 64–87) with no difference amongst recipients with or without minimal residual disease (P = 0.2992). Immune reconstitution was rapid, with mean CD3 and CD4 T-cell counts of 410/μL and 140/μL at day + 30. Cumulative incidence of acute GVHD and chronic GVHD was 36% and 26% but most patients with acute GVHD recovered rapidly with therapy. Lower rates of grade III-IV acute GVHD were observed with NK-cell alloreactive donors (P = 0.004), and higher rates of moderate/severe chronic GVHD occurred with maternal donors (P = 0.035).ConclusionThe combination of a CD45RA-depleted graft and NK-cell addback led to robust immune reconstitution maximizing the GVL effect and allowed for use of a submyeloablative, TBI-free conditioning regimen that was associated with excellent EFS resulting in promising long-term outcomes in this high-risk population.The trial is registered at ClinicalTrials.gov (NCT01807611).

Evolution of tisagenlecleucel use for the treatment of pediatric and young adult relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (B-ALL): Center for International Blood & Marrow Transplant Research (CIBMTR) registry results.

10016 Background: Tisagenlecleucel is an autologous CD19-directed chimeric antigen receptor (CAR) T-cell immunotherapy indicated for patients (pts) up to 25 y of age with B-ALL that is refractory or in second or later relapse. Since the pivotal ELIANA trial, pt characteristics now include pts < 3 y, pts with isolated central nervous system relapse, and pts with leukemia burden < 5%. Here we examine the impact of tisagenlecleucel on the pt treatment journey since FDA approval in 2017. Methods: Data were collected as a part of a noninterventional, prospective, longitudinal study using the CIBMTR registry. Pts were treated in the United States, Canada, Korea, or Taiwan. Results: As of May 4, 2023, 974 pts received tisagenlecleucel. Primary disease history has evolved since 2017. Notably, disease burden prior to infusion has decreased (≥50% blasts: 18% in 2018, 4% in 2022) and a higher proportion of pts received tisagenlecleucel while in morphological complete remission (34% in 2018, 51% in 2022). Between 2018 and 2022, the proportion of pts who were in third or greater relapse decreased (14% vs 2%, respectively). Pts ≥18 y had more prior exposure to blinatumomab and inotuzumab compared with pts < 18 y: 27% vs 16% and 17% vs 7%, respectively. The proportion of pts undergoing ≥1 hematopoietic stem cell transplantation (HSCT) before tisagenlecleucel infusion decreased (37% in 2018, 15% in 2022), coinciding with the use of tisagenlecleucel in earlier lines of therapy. Reporting of B-cell recovery was suboptimal. In total, 34.5% (314/911) of pts received postinfusion HSCT (reasons for HSCT were not captured for most pts); 8.5% (77/911) of pts received postinfusion HSCT to treat relapse, persistent/progressive disease, or positive minimal residual disease. Although the overall rate of postinfusion HSCT did not change, pts with high-risk cytogenetics showed a decrease in HSCT frequency. Previously, most pts < 3 y with KMT2A rearrangement received a HSCT. Since 2017, only 16% (12/75) of pts < 3 y received a prior HSCT despite 72% (54/75) having a KMT2A rearrangement. Furthermore, of the pts with rearrangement, only 43% (23/53) received a HSCT postinfusion. With censoring for HSCT, median RFS improved: 18 mo in 2018, 27 mo in 2020, and not estimable in 2021. OS was not substantially affected by HSCT censoring; 36-mo probabilities (95% CI) with and without censoring were 66 (61-71) and 62 (57-66), respectively. Conclusions: Pediatric and young adult pts with r/r B-ALL are receiving tisagenlecleucel earlier in the course of their disease treatment, reducing the use of HSCT for r/r disease, and prolonging RFS. As both real-world and clinical trial data supporting the curative potential of tisagenlecleucel grow, the use of HSCT in pts with remission after CAR-T should be carefully evaluated.

Flotetuzumab as a salvage immunotherapy in advanced CD123-positive hematological malignancies, a phase 1 pilot study

CD123 “expression” is common in hematological malignancies, including acute lymphoblastic leukemia (ALL). Flotetuzumab is a novel, investigational CD3/CD123 DART®. We conducted a phase 1 study evaluating safety and efficacy of flotetuzumab in relapsed/refractory ALL (Cohort A) and other advanced CD123-positive hematological malignancies (excluding myeloid malignancies) (cohort B). Thirteen patients (9 in Cohort A and 4 in Cohort B) were treated at dose level 1 (500 ng/kg/day) before early closure due to discontinuation of drug development by sponsor. Two dose limiting toxicities (Grade 4 thrombocytopenia and neutropenia) occurred in one patient in Cohort B. Cytokine release syndrome occurred in most patients (85%), all being grade ≤2. Responses only occurred in Cohort B, with a partial response in one patient with Hodgkin’s lymphoma and morphological complete remission in the bone marrow in one patient with blastic plasmacytoid dendritic cell neoplasm. In conclusion, flotetuzumab had a manageable safety profile in advanced CD123-positive hematological malignancies.

Transplant versus no transplant in myelodysplastic syndrome and acute myeloid leukemia with TP53 mutation; a referral center experience.

A remarkably high rate of post-transplant relapse in patients with TP53-mutated myelodysplastic syndrome/acute myeloid leukemia (MDS/AML) calls to question the utility of allogeneic stem cell transplant (HSCT). We, therefore, performed a retrospective analysis to compare the outcomes between HSCT (N = 38) versus non-HSCT (N = 45) approaches. Patients in the HSCT cohort were younger (median age 63 vs. 72) while patients in the non-HSCT cohort more commonly had complex karyotype with chromosome 17 aberrancy and 5q deletion (p < .01). A total of 69 TP53 variants including 64 pathogenic variants, and 5 variants of undetermined significance were detected. Nine patients (4 in HSCT and 5 in non-HSCT) had multi-hit TP53 variants. After induction: 57.9% versus 56.6% in the HSCT versus non-HSCT cohort achieved morphologic complete remission. Median time to HSCT was 6 months and median follow-up was 15.1 months for HSCT and 5.7 months for non-HSCT. Median disease-free survival (DFS) and overall survival (OS) were 11.7 and 15.9 months for HSCT, and 4.1 and 5.7 months for non-HSCT cohorts, respectively. Non-relapse mortality at 12 months was 22% versus 44% for HSCT versus non-HSCT. In the HSCT cohort, the rate of grade II-IV acute and chronic graft-versus-host disease (GVHD) was 55% and 18%, respectively. None of the patients from the non-HSCT cohort were alive while four patients from the HSCT cohort were alive, in remission, and without GVHD (GRFS) at the time of abstraction. Better treatment strategies for patients with TP53-mutated MDS/AML remain an area of unmet clinical need.

CD19-Specific CAR-T Cell Treatment of 115 Children and Young Adults with Acute B Lymphoblastic Leukemia: Long-term Follow-up.

Chemotherapy has been the primary treatment for patients with B-cell acute lymphoblastic leukemia (B-ALL). However, there are still patients who are not sensitive to chemotherapy, including those with refractory/relapse (R/R) disease and those experiencing minimal residual disease (MRD) re-emergence. Chimeric antigen receptor-T lymphocytes (CAR-T) therapy may provide a new treatment option for these patients. Our institution conducted a single-arm prospective clinical trial (ChiCTR-OPN-17013507) using CAR-T-19 to treat R/R B-ALL and MRD re-emergent patients. One hundred and fifteen patients, aged 1-25 years (median age, 8 years), were enrolled, including 67 R/R and 48 MRD re-emergent CD19-positive B-ALL patients. All patients achieved morphologic complete remission (CR), and within 1 month after infusion, 111 out of 115 (96.5%) patients achieved MRD-negative CR. With a median follow-up time of 48.4 months, the estimated 4-year leukemia-free survival (LFS) rate and overall survival (OS) rate were 68.7%±4.5% and 70.7%±4.3%, respectively. There were no significant differences in long-term efficacy observed among patients with different disease statuses before infusion (4-year OS: MRD re-emergence vs. R/R B-ALL, 70.6%±6.6% vs. 66.5%±6.1%, p=0.755; 4-year LFS: MRD re-emergence vs. R/R B-ALL, 67.3%±7.0% vs. 63.8%±6.2%, p=0.704). R/R B-ALL patients bridging to transplantation after CAR-T treatment had a superior OS and LFS compared to those who did not. However, for MRD re-emergent patients, there was no significant difference in OS and LFS, regardless of whether they underwent hematopoietic stem cell transplantation or not. CD19 CAR-T therapy effectively and safely cures both R/R B-ALL and MRD re-emergent patients.

Highly Curative Treatment of High-Risk Acute Promyelocytic Leukemia: Induction and Consolidation with ATRA+ATO+anthracyclines and Maintenance with ATRA+RIF.

The aim of the study was to evaluate the efficacy and safety of induction and consolidation with all-trans retinoic acid (ATRA) +arsenic trioxide (ATO) +anthracyclines and maintenance with ATRA +Realgar-Indigo naturalis formula (RIF) for high-risk APL. Twenty-one patients with high-risk APL treated with ATRA+ATO+ anthracyclines for induction and consolidation and ATRA+RIF for maintenance from 2012 to 2021 were analyzed. Endpoints include morphological complete remission (CR) and complete molecular remission (CMR), early death (ED) and relapse, survival and adverse events (AEs). After induction treatment, all 21 patients (100%) achieved morphological CR and 14 people (66.7%) achieved CMR. Five of the 21 patients did not undergo immunological minimal residual disease (MRD) examination after induction; however, 14 of the remaining 16 patients were MRD negative (87.5%). The median time to achieve CR and CMR was 26 days (range: 16-44) and 40 days (range: 22-75), respectively. The cumulative probability of achieving CR and CMR in 45 days was 100% and 76.2% (95% CI: 56.9-91.3%), respectively. All patients achieved CMR and MRD negativity after the three courses of consolidation treatment. The median follow-up was 66 months (25-142), with no central nervous system relapse and bone marrow morphological or molecular relapse until now, and all patients survived with 100% overall survival and 100% event-free survival. Grade 4 adverse events (AEs) were observed in 3 patients (14.3%) during the induction period including arrhythmia (n = 1), pulmonary infection (n = 1) and respiratory failure (n = 1); and the most frequent grade 3 AEs were pulmonary infection, accounting for 62.0% and 28.6%, respectively, during induction and consolidation treatment, followed by neutropenia, accounting for 42.9% and 38.1%, respectively. For newly diagnosed high-risk APL patients, induction and consolidation with ATRA+ATO+anthracyclines and maintenance with ATRA+RIF is a highly curative treatment approach.

Idarubicin versus Doxorubicin in Acute Myeloid Leukemia: A Parallel Randomized Trial with Pharmacoeconomic Analysis

Background: Acute Myeloid Leukemia (AML) is the most common form of acute leukemia among adults. Treatment of acute leukemia has been divided into induction chemotherapy and post-remission therapy. The goal of induction chemotherapy, that consists of anthracycline and cytarabine, is to achieve morphologic complete remission (CR), but the main problem is that it has a high economic burden. Idarubicin is the anthracycline of choice used in AML, while doxorubicin, is mainly used in other types of cancer. The aims of this study were evaluating the use of doxorubicin versus idarubicin in the induction phase for the treatment of AML and analysis the impact of the adoption of this anthracycline in Egypt’s public health system. Methods: A randomized controlled trial was undertaken in 244 patients with AML. A decision tree was developed based on the clinical outcome of the study, safety and efficacy, aiming to get the expected cost of doxorubicin compared with idarubicin in AML management. Results: In the doxorubicin group, 52.5% had a CR, versus 49.2 % in the idarubicin group (P=0.6). The most common toxicities among the 2 groups were febrile neutropenia, diarrhea and vomiting. Oral mucositis (OM) was higher in the doxorubicin group (70.8% vs 37%, P=0.0001), while invasive fungal infections were greater in the idarubicin group (75% vs 88.7%, P=0.004). Doxorubicin arm had a lower cost than idarubicin arm in treatment success group (39,492 LE vs 44,323 LE). Conclusion: Doxorubicin provides a treatment option with comparable efficacy, toxicity profile and survival rates at a lower cost compared to the traditional treatment, idarubicin.

Results of Cynk-001-AML-001: A Phase I Multi-Dose Study Evaluating the Safety, Tolerability, and Persistence of Cynk-001 in Adults with De Novo or Secondary Acute Myeloid Leukemia in Morphologic Complete Remission with Minimal Residual Disease or Relapsed/Refractory AML

Introduction: Acute myeloid leukemia (AML) is a clinically and genetically heterogeneous disease often with suboptimal outcomes. While progress has been achieved in the treatment of AML, relapse remains a significant challenge. Novel therapeutic options aimed at attaining minimal residual disease (MRD) negative complete remission (CR) are expected to reduce the incidence of relapse and prolong survival. Evidence shows that natural killer (NK) cells can exhibit potent anti-leukemia activity against AML. CYNK-001 is a CD56+CD3- enriched, off-the-shelf, unmodified allogeneic NK cells expanded from placental CD34+ cells. Aim CYNK-001-AML-001 is a phase I multi-dose study evaluating the safety, tolerability, and persistence of CYNK-001 with or without recombinant human interleukin-2 (rhIL-2) in adults with de novo or secondary acute myeloid leukemia (AML) in morphologic complete remission (CR) with minimal residual disease (MRD) or relapsed/refractory (R/R) AML. Methods This Phase I, single-arm, dose escalation clinical trial (NCT04310592) enrolled patients 18-80 years with R/R AML or patient in MRD positive CR. Two lymphodepletion regimens were assessed. Patients in cohorts 1-3 underwent standard lymphodepletion with fludarabine (25 mg/m2/day) and cyclophosphamide (300 mg/m2/day) on days -5, -4 and -3. Subsequent cohorts received enhanced lymphodepletion with fludarabine (30 mg/m2/day) and cyclophosphamide (900 mg/m2/day) on days -6, -5, -4 and -3. Escalating doses of NK cells were administered following a standard 3+3 design, with 2 separate arms (MRD+ arm and R/R arm) starting with cohort 4. A starting dose of 600 million cells on days 0, 7, and 14 was escalated to a maximum dose of 1.8 billion cells on days 0, 7, 14 and 21. The primary objective of the study was to determine the maximum tolerated dose (MTD) or maximum planned dose (MPD) of CYNK-001 and to assess the safety of multiple infusions of CYNK-001 administered using a flat, non-weight-based dose as assessed by the frequency and severity of adverse events (AE). The secondary objective was to assess the clinical efficacy of CYNK-001 in AML subjects. Results 28 patients (17 with R/R AML and 11 with MRD-positive AML) were enrolled during dose escalation, and 27 received CYNK-001. The highest dose of NK cells administered was 1.8 billion cells X 4 in cohort 6b (patients with R/R AML). Treatment was well tolerated with no dose limiting toxicities (DLTs) even at the highest dose. No cases of neurotoxicity or GvHD were reported. Four cases of grade 2 CRS were reported but there were no cases of ≥ grade 3 CRS. Two incidences of grade 4 thrombocytopenia and one grade 4 decreased white blood cell count were noted in patients who had received enhanced lymphodepletion. In R/R AML patients treated with the highest dose of CYNK-001, 2 of 4 patients achieved an objective response of Morphologic Leukemia-Free State (MLFS) on Day 28. One of these patients has maintained a response to D120 and is continuing follow up. One of 3 patients with MRD +ve AML treated with 3 doses of 1.8 billion CYNK-001 cells per dose achieved MRD negativity until day 120 at which time a blast count of 1.6% was observed. Conclusion Treatment with CYNK-001 showed biological activity as evidenced by achievement of MLFS in R/R AML patients and eradication of AML MRD positivity in AML patients in morphologic CR. Therapy was generally well-tolerated, with no dose-limiting toxicities observed with even the highest dose of CYNK-001. This trial yielded important insights into the optimal approach to lymphodepletion and the potential clinical efficacy of allogeneic NK cells in R/R AML. Based on these results, this trial is now closed to further enrollment and future development activities will focus on next generation NK cell therapies edited to optimize persistence and efficacy and limit the requirement for enhanced lymphodepletion.

Outcomes of Children and Adolescents with Acute Myeloid Leukemia Given a Low-Versus Standard-Dose Chemotherapy Regimen for Remission Induction (CALSIII-AML18): A Multicenter, Phase 3, Randomized, Noninferiority Trial

Backgroun d: Intensive chemotherapy is recommended for remission induction of pediatric acute myeloid leukemia (AML). However, life-threatening complications are common especially in vulnerable populations. We investigated whether a low-dose chemotherapy (LDC) regimen would be noninferior to a standard-dose chemotherapy (SDC) regimen for induction remission.This study also aimed to assess whether LDC is not inferior to SDC in terms of survival outcomes. Methods: We conducted a randomized, noninferiority study in children with AML who were admitted to 14 medical centers in China. Patients were randomly assigned to receive two remission-induction courses of either low-dose chemotherapy (LDC) (cytarabine 10 mg/m 2, subcutaneous, q12 hours, 20 doses; mitoxantrone or idarubicin 5 mg/m 2, intravenous, days 1, 3 and 5; and G-CSF 5 mcg/kg, subcutaneous, daily, 10 doses) (n = 246) or standard-dose chemotherapy (SDC) (cytarabine 100 mg/m 2, intravenous, q12 hours, 20 doses; daunomycin 50 mg/m 2, intravenous, days 1, 3, 5; and etoposide 100 mg 2, intravenous, days 1 to 5) (n = 251). Depending on the risk of relapse, patients in complete remission (CR) in both arms received two to three cycles of intensive consolidation chemotherapy and/or underwent hematopoietic stem cell transplantation (HSCT). The primary endpoint was to compare CR rates in patients randomized to the LDC or SDC regimens. The secondary endpoints were to determine the safety of the LDC regimen and to compare the time to platelet and neutrophil count recovery in the two groups. Finally, in a multivariate analysis, we determined the impact of the type of remission induction on the outcome. This trial is registered at chictr.org as # ChiCTR-18000015883 and has been completed. Results: From June 2018 to June 2022,497 participants aged &amp;lt;18 years with de novo AML were randomized. Patients with Down syndrome, promyelocytic leukemia, or megakaryoblastic leukemia were excluded. There were no significant differences in age, sex, or genotype between the two arms. Complete morphologic remission with or without platelet recovery (CR/CRi) was attained in 72.8% and 70.3% of patients assigned to the LDC and SDC arms, respectively, after Induction I and in 95.5% and 95.7%, respectively, after Induction II ( P = .545 for Induction I and .898 for Induction II). Residual disease &amp;lt; 0.1%, as measured by flow cytometry, was observed in 54.8% and 58.9% of patients in the LDC and SDC arms, respectively, after Induction I and in 85.9% and 84.4%, respectively, after Induction II ( P = .229 for Induction I and .827 for induction II). Median time to neutrophil count recovery was 15 days for patients in the LDC arm vs. 22 days for those in the SCD arm after Induction I ( P&amp;lt; .001) and 12 days vs. 18 days for patients in the respective arms after Induction II ( P &amp;lt; .001). Median time to platelet count recovery was 13 days for patients in the LDC arm vs. 19 days for those in the SCD arm after Induction I ( P &amp;lt; .001) and 3 days vs. 8 days for patients in the respective arms after Induction II ( P&amp;lt; .001). Grade 3 and 4 toxicities were significantly lower in patients in the LDC arm than those in the SDC arm. In Induction I, febrile neutropenia occurred in 75.2% and 93.2% ( P &amp;lt; .001), colitis in 3.7% and 10.7% ( P = .003), and gastrointestinal hemorrhage in 0.4% and 4.4% ( P = .006) in the LDC and SDC arms, respectively. In Induction II, febrile neutropenia occurred in 34.4% and 66.9% ( P &amp;lt; .001), lung or sinus infection in 2.8% and 9.3% ( P = .008), and sepsis in 3.3% and 10.7% ( P = .004), in the LDC and SDC arms, respectively. There was no significant difference in treatment-related mortality between the two treatment arms ( P = 204).Compared to patients in the SDC arm, patients in the LDC arm had noninferior 3-year EFS of 61.9% (95% CI: 55.7 to 68.8) vs. 62.2% (95% CI: 56.1 to 68.8)( P = .994) (Figure 1A), and 3-year OS of 81.0% (95% CI: 75.7 to 86.6) vs. 83.2% (95% CI: 78.2 to 88.5) ( P = .485) (Figure 1B). In a multivariate analysis considering known prognostic indicators in pediatric AML, treatment arm was not associated with outcome. Conclusion: In children with AML, remission induction with a low-dose chemotherapy regimen with concurrent G-CSF administration was well tolerated and was associated with CR, EFS, and OS rates that were not inferior to those of patients treated with a standard chemotherapy regimen.

Concurrent BCR::-ABL1 and CBFB Rearrangement in De Novo Acute Myeloid Leukemia

Introduction Acute myeloid leukemia (AML) is known for its genetic heterogeneity. Several recurrent genetic variants have been characterized including AML-defining chromosomal rearrangements involving the core binding factor (CBF), such as inv(16)/t(16;16)/ CBFB:: MYH11. 1 Less common is a subset of AML characterized by the Philadelphia chromosome (Ph+), generating a BCR::ABL1 fusion protein. 2 The Ph+ AML subtype is associated with poor prognosis and treatment resistance. 3,4 Co-occurrence of CBFB rearrangement and BCR::ABL1 fusion is rare, representing a subgroup with unique clinical and molecular features. To date, there have been less than 30 cases reported in the literature. 5-8 Case Description A 62-year-old male presented to hospital with headaches, visual changes, weakness, and a nodular rash on his back, with leukocytosis, thrombocytopenia, and 42.5% circulating blasts. A bone marrow (BM) aspirate and biopsy was diagnostic of AML with 56% myeloblasts. RT-PCR was positive for an e19a2 BCR::ABL1 fusion transcript coding for p230 kDa fusion protein (p230) and CBFB: :MYH11 fusion gene transcript. Cytogenetics identified a complex karyotype with an inv(16) and a Ph chromosome (46,XY,t(1;14)(p32;q24),t(9;22)(q34;q11.2),inv(16)(p13.1q22)[10]), consistent with concurrent BCR::ABL1 and CBFB::MYH11 rearrangements within the same clonal population of cells. Treatment consisted of hydroxyurea for cytoreduction, 7+3 induction, one cycle of low dose cytarabine consolidation, and oral azacytidine maintenance, in combination with dasatinib. He did not receive Gemtuzumab ozogamicin (GO) given patient preference and comorbidities. Post-induction course was complicated by febrile neutropenia due to Enterococcus Faceium bacteremia, pre-renal acute kidney injury, and dasatinib-related complications including rash and transaminitis. These issues resolved by holding dasatinib for 15 days. Complete morphologic remission (CR) was obtained by Day 33 post-induction and no fusion gene transcripts were detectable by nested RT-PCR from BM aspirate on day 49 post-induction, nor day 76 post-consolidation The patient was ineligible for an allogeneic stem cell transplant given his poor performance status. At present, the patient remains alive and well, continuing on maintenance with oral azacytidine and dasatinib. Discussion We present the only case, to our knowledge, of a concurrent BCR::ABL1 p230 isoform and CBFB::MYH11 with de novo AML. Based on our literature search, 26 cases have been reported. BCR::ABL1 and CBFB::MYHII rearrangements in de novo AML potentially confers an intermediate to favorable prognosis with outcomes comparable to those of CBF-AML. Studies suggest that this entity may be more akin to AML with inv(16) rather than CML-BP with inv(16), thereby retaining favorable prognosis. 5,9-11 There are no formal guidelines for management of de novo AML with concurrent BCR::ABL1 and CBFB rearrangements. Traditional chemotherapy treatment strategies for Ph+ AML are often ineffective in these cases. The presence of BCR::ABL1 fusion transcript raises the possibility of utilizing TKIs targeting the BCR::ABL1 kinase domain. In our case, the patient achieved rapid CR with induction chemotherapy and dasatinib, but experienced multiple complications, precluding further intensive chemotherapy and allogeneic stem cell transplantation. This case raises a number of questions, including the optimal timing, combination, and duration of TKI therapy in the context of dual rearrangement de novo AML. This patient subgroup may benefit from intensive chemotherapy regimens and TKIs. Prospective monitoring of these cases is warranted to assess outcomes in comparison to Ph+ AML without coinciding CBFB rearrangement. This case report underscores the importance of comprehensive genetic profiling in Ph+ AML to determine the genetic landscape and individualize therapeutic strategies.

BAX Mutated Clonal Hematopoiesis Arises Following Treatment with the BCL2 Inhibitor Class of Therapeutics across a Range of Hematological and Non-Hematological Neoplasms

Clonal hematopoiesis (CH) is an age-related phenomenon characterized by the expansion of genomically mutated hematopoietic clones with a selective fitness advantage. Venetoclax, a selective BCL2 inhibitor, has established efficacy in hematological malignancies such as chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML). Our previous studies described the emergence of deleterious BAX variants within the myeloid compartment of patients (pts) receiving venetoclax for CLL (Blombery, Blood2022). Whether this phenomenon is specific to venetoclax and the CLL disease context is currently unknown. We therefore aimed to investigate the prevalence and pattern of BAX-mutatedCH across different hematological and non-hematological neoplasms in response to BCL2 inhibitor therapy (both venetoclax and BGB-11417). We first examined pts with AML in complete morphologic remission after venetoclax exposure in both the newly diagnosed (CAVEAT; Chua, JCO 2020) and early relapse (VALDAC; Tiong, ASH 2022) settings using unique molecular index-based error-corrected next generation sequencing with a sensitivity of 0.5% (QIAseq targeted DNA panel). BAX variants were detected in remission samples in 11/20 (55%) and 9/26 (35%) pts in these cohorts, respectively, after a median of 9- and 4-months post venetoclax. This represented a significant higher incidence compared to remission samples from pts with newly diagnosed AML post conventional cytotoxic chemotherapy without venetoclax (6/87 [7%]; adjusted p&amp;lt;0.01 for both pairwise comparisons). Having observed the increased frequency of BAX-mutated CH in remission in myeloid (AML) and lymphoid (CLL) neoplasms, we then investigated whether BAX variants may be acquired in response to BCL2 inhibitor therapy outside the context of hematological neoplasm. We assessed a cohort of pts with metastatic breast cancer who received venetoclax in combination with tamoxifen (mBEP; Lok, Cancer Discover 2019), and detected BAX variants from peripheral blood samples in 5/16 (31%) pts (median age 66) after a median duration of 20 (range 13-44) months on venetoclax. In contrast, no BAX variants were detected in a similarly aged control cohort of 50 pts (median age 62) with breast cancer without exposure to venetoclax (p=0.01). The rates of any CH-related mutation were 75% and 50% pts, respectively (p=0.09). No pt developed MDS or AML during follow up in the mBEP cohort. Finally, to explore whether emergence of BAX-mutated CH is specific to venetoclax as an agent, we studied a cohort of 9 pts with CLL who had received BGB-11417, a more potent and selective BCL2 inhibitor; median treatment duration 13 months. Notably, we observed the emergence of BAX variants in 2/9 (22%) pts in this cohort. The characteristics of the BAX variants (n=88) in 28 pts (AML, CLL or breast cancer) are summarized in Figure 1; 3 variants (in 3 pts) were detectable in pre-treatment samples. Over half of the missense (n=22) or in-frame variants (n=1) were clustered in the C-terminus of the BAX protein, while truncating variants (n=65) were observed throughout the gene. The median number of BAX variants per pt was 2, with 32% of pts having ≥3 variants (max=13). The median VAF was 1.4%, and only 16% of variants had a VAF &amp;gt;5%. The number and VAF of BAX variants did not significantly correlate with the duration of therapy. Among 12 pts with AML who had serial testing (median inter-test interval 10 months), BAX variants (n=24) did not significantly change in VAF (median Δ 0.7%) with time after initial acquisition (Pearson's coefficient 0.17). To clarify the compartments affected by BAX variants we performed single-cell combined DNA/protein sequencing (Tapestri) of a sample with multiple BAX variants and demonstrated their presence in multiple independent clones with myeloid-biased lineage but also within the natural killer cell compartment ( Figure 2). In summary, the emergence of BAX-mutated CH appears to be a generalized phenomenon of adaptive hematopoiesis that occurs across both hematological and non-hematological malignancy settings as well being observed with other BCL2 inhibitors consistent with a therapeutic class effect. Further research is needed to understand the contribution of this phenomenon to the subsequent development of clinically relevant hematological abnormalities and its implications for future therapeutic resistance.

Venetoclax and Azacitidine for Molecular Relapse during First Line Intensive Chemotherapy in Patients with NPM1 Mutated or Core Binding Factor (CBF) AML. a Study from the Dataml Registry

Introduction: Molecular follow-up (FU) for AML patients (pts) with NPM1 mutation, RUNX1::RUNX1T1 or CBFB::MYH11 fusion transcripts has been established over the last ten years. Real-time quantitative PCR (qPCR) is the gold standard for the evaluation of measurable residual disease (MRD) in pts undergoing intensive chemotherapy (IC). Failure to achieve a deep molecular response is a strong predictive factor of relapse and survival and may guide post remission therapy (Ivey A, NEJM 2016). Moreover, the ELN MRD working party recommended a schedule for molecular FU and recently established a definition of molecular relapse (Heuser M, Blood 2021). However, there is no therapeutic consensus for pts with molecular relapse before overt clinical relapse. Frontline allogeneic hematopoietic cell transplantation (alloHCT), salvage IC or even waiting for morphological relapse in order to screen molecular characteristics of the relapsing disease or propose a clinical trial, may be discussed with pts. Venetoclax with azacitidine (VEN/AZA) was recently approved in unfit AML pts and demonstrated a particular efficacy in NPM1-mutated AML. In this study, we thought to describe the safety and efficacy of VEN/AZA in pts with NPM1 mutated or CBF AML in molecular relapse after first line IC. Methods: Pts of the DATAML registry with the following criteria were included in this study : AML with NPM1 mutation, RUNX1::RUNX1T1 or CBFB::MYH11 transcripts, first line IC, morphological complete remission (CR), no alloHCT in first line, regular monitoring of MRD by qPCR in bone marrow (BM) and/or blood, molecular relapse defined according to ELN2021 guidelines on two successive samples, at least one cycle of VEN/AZA. Pts with molecular relapse followed by morphological relapse before VEN/AZA or those who relapsed after alloHCT were not included. Treatment: First line IC was cytarabine 200 mg/m² d1-7 with idarubicin 9mg/m²/d1-5 or daunorubicin 90mg/m²/d1-3 in pts 18-60y or cytarabine 100 mg/m² d1-7 with idarubicin 8mg/m²/d1-5 and lomustine 200 mg/m²/d1 in pts &amp;gt; 60y. Post remission therapy was intermediate or high dose cytarabine or mini-consolidations according to age and performance status. Midostaurin was added in FLT3-mutated pts. At time of molecular relapse, pts received off label venetoclax 400 mg/d (d1-14, d1-21 or d1-28 according to centers) with no ramp-up and azacitidine 75 mg/m²/d subcutaneously (d1-5, d8-9). Antifungal/antibiotic prophylaxis and G-CSF use were not systematically recommended. Results: Twenty-two pts treated with VEN/AZAfrom 21/09/2020 to30/03/2023 were included. Their characteristics at diagnosis were: female (n= 14), median age 55y (range 27-71), de novo AML (n=21), median WBC (68 giga/L, range 2.32-339.7), NPM1 mutation (n=20), CBFB::MYH11 (n=2), FLT3 mutation (n=13). All pts achieved first CR after one cycle of induction chemotherapy. Pts received a median of three consolidation cycles. All but three pts had negative MRD or low level MRD (LL-MRD) in blood and/or BM at the end of consolidation. The median time between CR1 and molecular relapse was 9.5 months (range, 1-50). The median time between molecular relapse and first VEN/AZA cycle was 51 days. During first cycle of VEN/AZA, 12, 5 and 5 pts received 14, 21 or 28 days venetoclax, respectively; 19 were treated as out-pts, 4 received posaconazole and GCSF was used in 11 pts. 12 and 3 pts had grade 3-4 neutropenia or febrile neutropenia (FN), respectively. Only 3 pts (14%) were hospitalized for FN. The median number of VEN/AZA cycles was 2 (range 1-12). After C1+/-C2, 10 (45%) and 11 pts (55%) had undetectable or LL MRD in blood, respectively (Fig1). 20 pts were bridged to alloHCT in morphological CR after a median of 2 cycles (range, 1-4). Only one pt had a molecular progression before transplantation after 2 cycles. Two pts died, one had a molecular relapse after 7 cycles and progress rapidly to frank relapse, the other one died of post-transplant complication while in CR with undetectable MRD. All other pts remained in CR at date of last news. With a median FU from D1C1 of 13.5 months, median OS wat not reached and 1y-OS was 86% (Fig2). Conclusion: In the setting of molecular relapse, VEN/AZA is safe, prevent overt relapse, and induce a high rate of molecular response before alloHCT. Molecular relapse becomes a major therapeutic challenge. Clinical trial endpoints should include the treatment of molecular relapse as an event for RFS and EFS estimation.

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.

Assessment of Outcomes of Consolidation Therapy By Number of Cycles of Blinatumomab Received in Newly Diagnosed Measurable Residual Disease Negative Patients with B-Lineage Acute Lymphoblastic Leukemia: In the ECOG-ACRIN E1910 Randomized Phase III National Clinical Trials Network Trial

Introduction: ECOG ACRIN E1910 is a randomized phase III trial that showed that adults with newly diagnosed BCR::ABL1 negative acute lymphoblastic leukemia (ALL) who become MRD negative (&amp;lt;0.01%) after induction chemo who receive blinatumomab with conventional chemotherapy (chemo) have improved survival compared with those who received chemo only (Litzow et al, Blood (2022) 140: Supplement 2, LBA-1). However, not all pts were able to receive all four planned cycles of blinatumomab in consolidation. In this report we assessed outcomes of pts in the blinatumomab arm of the trial who received all 4 cycles of blinatumomab compared to those who received 1-2 cycles. Methods: Patient between the ages of 30 and 70 with newly diagnosed BCR::ABL1 negative B-lineage ALL were enrolled and initially received 2.5 months of combination induction chemo utilizing a BFM-like regimen adapted from the E2993/UKALLXII clinical trial, with pegaspargase (after induction only for patients &amp;gt;=55 years of age) and addition of rituximab for CD20 positive patients. After remission induction (step 1) pts in morphologic complete remission (CR/CRi) received an intensification course of high dose methotrexate with pegaspargase for CNS prophylaxis (step 2). At the conclusion of step 2, remission and MRD status were determined centrally by 6-color flow cytometry with MRD negativity defined as &amp;lt;0.01%. In the primary analysis subset, MRD negative patients were randomized to receive an additional 4cycles of consolidation chemo or 2 cycles of blinatumomab at 28 mcg/day (flat dose) for 28 days each cycle followed by 3 cycles of consolidation chemo, another 4-week cycle of blinatumomab (3rd cycle of blinatumomab) followed by an additional cycle of chemo and then a 4th cycle of blinatumomab (step 3). Following completion of consolidation chemo +/- blinatumomab, pts were given 2.5 years of POMP maintenance therapy timed from the start of the intensification cycle (step 4). Estimates of OS were calculated using the Kaplan-Meier method. Comparison of OS between treatment arms were conducted using the stratified log-rank test and Cox proportional-hazards model with age, CD20 status, rituximab use, and whether pts intend to receive HSCT or not as stratification factors. As the number of cycles needed to optimize outcome has not been studied, an unplanned landmark analysis was used to compare OS of pts in the blinatumomab arm who received all 4 cycles o those who received 1-2 cycles. Time 0 was chosen as 9 months post step 3 randomization (the time that patients were supposed to complete 4 cycles of blina). Four pts who received blinatumomab but died within 9 months post step 3 randomization were therefore excluded from this analysis. Results: The study was activated on December 17, 2013 and closed to enrollment on October 15, 2019. 772 pts were screened for the trial and 488 were enrolled on step 1 induction therapy. The median age of the pts was 51 years (range 30-70). 224 MRD negative pts were randomized, 112 pts to each arm. In the blinatumomab arm 12 pts received 1 cycle (11%), 32 pts received 2 cycles (29%), 4 pts received 3 cycles (4%) and 63 pts received 4 cycles (57%). The OS of pts who received 1-2 cycles of blinatumomab was compared to control (Figure 1) The difference was not significant (hazard ratio 0.62, 95% CI 0.28 to 1.34, p=0.22). Fig 2 compares the survival of those who received 1-2 cycles to those who received 4 cycles ( (HR: 0.39, 95% CI 0.12 to 1.16, p=0.076). Conclusion: The addition of blinatumomab to consolidation chemotherapy resulted in a significantly better overall survival compared to chemotherapy alone in pts with newly diagnosed B-lineage ALL who were MRD negative after intensification. This represents a new standard of care for pts aged 30-70 years with BCR::ABL1 negative ALL. The optimal dose and number of cycles is however unknown. In this unplanned subgroup analysis we demonstrate that a survival benefit can only be confirmed in patients who receive the intended 4 cycles of blinatumomab during consolidation. Further studies will be needed to determine if fewer cycles can provide a similar benefit.

Salvage Autologous Peripheral Blood Stem Cell Transplantation after the Development of tMDS or AML in Multiple Myeloma Patients

Multiple Myeloma (MM) patients are often treated with high-dose chemotherapy and autologous stem cell transplantation (ASCT) for disease control. Lenalidomide is typically used as maintenance but results in an estimated 3.3% chance of developing a therapy-related myeloid neoplasm (TMN) typically myelodysplastic syndrome (MDS) or acute myelogenous leukemia (AML). This complication is often devastating with a median survival for those with a TMN of just 13 months. Over the past 6 years, 4 patients with multiple myeloma who developed a TMN were treated with a salvage ASCT using banked stem cells collected prior to their initial ASCT and before lenalidomide maintenance. None of these patients qualified for an allogeneic transplant. Melphalan 140 - 200 mg/m2 was used as conditioning prior to infusion of the peripheral blood stem cells, resulting in successful MDS/AML disease control. Case 1 = 61-year-old man with MM initially treated with CyBorD then transplanted in 2010. Post transplant treatment included lenalidomide maintenance, followed by a variety of salvage regimens over the next 7 years including thalidomide, carfilzomib, daratumumab and pomalidomide. He developed cytopenias evaluated by bone marrow biopsy in May 2017. This showed tMDS (Karyotype 47-48, XY, der (5)t(5:20)(q11.1;q11.1), +19, der(21:22)(q10:q10),+2~3mar[cp11]/46-48,idem,-der(5),+20[cp5]/46,XY[4]. FISH confirmed deletion 5q in 76% and loss of chromosome 5 in 6.5% of cells. NGS showed a frame shift mutation of TP53 at a variant allele frequency of 92.5%. He underwent a second ASCT in Aug 2017 and recovered normal hematopoiesis within three weeks. Unfortunately, he developed an aggressive relapse of his multiple myeloma 9 months later and succumbed from refractory multiple myeloma 14 months after the salvage transplant, without evidence of MDS. Case 2 = 72-year-old man with MM initially treated with CyBorD then an ASCT in May 2015. Lenalidomide maintenance was continued until October 2017 when he developed severe thrombocytopenia and circulating blasts. A bone marrow biopsy showed tMDS EB-1. Cytogenetics 46, XY t(3:21) (q26.2,q22) [18]/46, XY[2]. He received a second ASCT after melphalan 140 mg/m2 in Oct 2017 followed by recovery of normal blood counts. Bone marrow biopsy showed complete remission. He remains in remission from both the multiple myeloma and MDS almost 6 years later without any further therapy. Case 3 = 65-year-old man with MM treated with bortezomib + dexamethasone followed by ASCT in Aug 2012. He received maintenance lenalidomide for 4 years but then progressed. In Jan 2018 he developed pancytopenia and bone marrow biopsy demonstrated MDS with ringed sideroblasts. Cytogenetics were normal but NGS showed mutations of ASXL1, RUNX1, SF3B1, SETBP1 and DNMT3A. He underwent a second ASCT using his banked stem cells after melphalan 140 mg/m2 in Jan 2018 followed by full hematopoietic recovery. A repeat bone marrow biopsy in March 2022 showed persistent MDS harboring ASXL1, SF3B1, and DNMT3A mutations, but no detectable RUNX1 or SETBP1 abnormalities. His multiple myeloma remains in remission &amp;gt;5 years later. He receives only intermittent erythropoietin to maintain a Hgb of 11. Case 4 = 58-year-old man with MM initially treated with CyBorD followed by an ASCT in May 2014. He received lenalidomide maintenance but relapsed multiple times after 4 years ultimately complicated by renal failure requiring permanent dialysis. In March 2022 he developed pancytopenia. Bone marrow biopsy showed 15% blasts harboring del(5q), del(17p) and trisomy 8 by FISH. NGS demonstrated a mutation of ASXL1, and a copy number loss of TP53. Six months of decitabine did not improve his blood counts. In Dec 2022 he underwent a second ASCT after melphalan 140 mg/m2. A repeat bone marrow biopsy in Feb 2023 showed a complete morphological remission with a normal NGS. He is off all treatment 8 months post-transplant other than erythropoeitic support due to ongoing dialysis-dependent renal failure. The development of TMN is an uncommon but devastating event in patients with multiple myeloma after ASCT and lenalidomide maintenance. These patients responded well to a salvage ASCT using banked stem cells. This approach was well tolerated and provided durable hematopoietic recovery. Second ASCT using banked autologous stem cells should be considered in such patients who are not otherwise candidates for allogeneic transplantation.

Final Results of the AIEOP (Associazione Italiana Ematologia/Oncologia Pediatrica) AML 2013 Prospective Randomized Trial in Childhood Acute Myeloid Leukemia (AML)

Background: Treatment of children with newly diagnosed AML is based on induction therapy, followed by consolidation approaches which differ according to the group of risk patients (pts) are allocated to. In this respect, most treatment protocols stratify pts into 3 risk groups, namely standard (SR), intermediate (IR) and high-risk (HR), mainly based on the molecular/cytogenetic characterization and values of measurable residual disease (MRD) at the end of induction therapy. We report the outcomes of 371 pts with de novo AML other than acute promyelocytic leukemia (aged 0-18) enrolled in the randomized trial AIEOP AML 2013 (EudraCT:2014-000652-28). Patients and methods: pts were diagnosed and enrolled in the trial from 06/2015 to 06/2022 at 33 Centers affiliated to the AIEOP group. Main pt characteristics and criteria used for stratification are shown in Table 1. A marker of recurrent molecular lesions was detected at diagnosis for 247 cases out of the 371 enrolled (67%). Monitoring of flow-cytometry MRD at the end of the 1 st and 2 nd induction course was centrally performed in all pts but 7. The 1 st induction course was common for all pts (ICE scheme), while, then, SR pts were treated with 4 additional chemotherapy courses, all including high-dose cytarabine (HD-Ara-C). IR and HR pts were randomized to receive either a 2 nd ICE or the FLA-Liposomal Doxorubicin (L-Doxo) scheme as 2 nd induction course. IR pts were given 3 additional consolidation courses including HD-Ara-C with other agents or, in the presence of an HLA-compatible sibling, 1 consolidation course followed by allogeneic hematopoietic stem cell transplantation (HSCT). Pts of the HR group were consolidated with 2 courses of HD-Ara-C combined with other cytotoxic agents and, then, had an indication to receive HSCT from either a donor compatible for &amp;gt; 9/10 HLA loci or from an HLA-partially matched relative. Data cut-off for the analysis was March 31, 2023. Results: The proportion of pts allocated to the SR, IR and HR groups were 19% (72 pts), 23% (81 pts) and 58% (218 pts), respectively. Overall, 92% of pts obtained morphological complete remission (CR) at the end of the 2 induction courses [as compared to 87% of the previous AIEOP AML 2002 study (Pession et al. Blood 2012), p&amp;lt;0.05]. Twenty-five pts (7%) experienced a primary induction failure. Only 3 pts died during or after the 2 induction courses, while the subsequent cumulative incidence of 3-yr non-relapse mortality in continuous CR was 6.8%. Leukemia recurrence occurred in 63 pts, this leading to a 3-yr cumulative incidence of relapse of 18.9%. With a median follow-up of 4.5 yrs (range 0.8-8), the 3-yr probabilities of overall (OS) and event-free survival (EFS) were 83.9% and 68.5% (Figure 1), respectively, both values being significantly better (p&amp;lt;0.01) than those of the AIEOP AML 2002 study. The 3-yr OS of SR, IR and HR pts were 99.2%, 84.2% and 79.4%, respectively (p=0.01). The 3-yr estimate of disease-free survival (DFS) was 74.3%, with no difference among the 3 risk groups. The EFS did not differ in IR and HR randomized to receive either a 2 nd ICE or the FLA-L-Doxo scheme as second induction course. Levels of flow-cytometry MRD after the 2 nd induction course strongly influenced the probability of EFS which was 76% and 48% in pts with an MRD value &amp;lt; or &amp;gt;0.1%, respectively (p&amp;lt;0.01). Allogeneic HSCT was performed in 160 pts; in these pts, the 3-yr probabilities of OS and DFS were 87.7% and 85.1%, respectively, with no difference according to the type of donor employed. The DFS of the 10 IR pts given HSCT was 100% as compared to 72.1% of the 71 not transplanted (p=0.07). The outcome of infants treated in this study was particularly good, since their 3-yr probability of EFS was 78.3%. The 3-yr EFS of the 35 pts with FLT3-ITD and of the 75 with KMT2-A rearrangements were 57.1% and 64.7%, respectively. Conclusions: These results indicate that in children enrolled in the trial AIEOP AML 2013 the 3-yr OS and EFS overcomes 80% and approaches 70%, respectively, with a significant improvement as compared to the previous AIEOP protocol. Disease recurrence/primary resistance were the main cause of treatment failure, while the probability of DFS did not differ among the 3 different risk groups, this finding indicating that tailoring of consolidation therapy according to the risk profile was successful in improving the outcome of pts with worse prognostic characteristics. The use of FLA-L-Doxodid not offer any advantage over repeating a 2 nd ICE.

Analysis of Safety and Efficacy of Avapritinib As Targeted Therapy for Pediatric Acute Myeloid Leukemia Patients with KIT Mutation after Transplantation

Objective: To investigate the safety and efficacy of Avapritinib in pediatric acute myeloid leukemia (AML) with KIT mutation after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Methods: The clinical data of 6 AML patients with KITmutation and RUNX1::RUNX1T1 fusion gene positive in Children's Hospital of Soochow University were retrospectively analyzed, including 2 cases of KIT:N822K, 3 cases of KIT: exon17 and 1 case of KIT: Asp816Tyr. After achieving complete remission in morphology, allo-HSCT was performed. The clinical outcomes of prophylactic therapy (2/6) and preemptive intervention (4/6) with Avapritinib after complete stem cell engraftment were observed, and the adverse events during treatment were recorded. Results: Adverse events occurred in 4 of the 6 patients, among whom neutropenia was the most common (4/6), followed by facial edema (2/6) and thrombocytopenia (1/6). 2 patients who received prophylactic treatment achieved morphological complete remission, and minimal residual disease (MRD), fusion gene and KIT mutations were all negative. 4 patients received preemptive intervention because of RUNX1::RUNX1T1 fusion gene turned positive after allo-HSCT, and 1 patient's RUNX1::RUNX1T1 turned negative after single-agent Avapritinib treatment for 2 months. 2 patients did not achieve continuous RUNX1::RUNX1T1 negative after preemptive therapy with Decitabine (DAC) and donor lymph infusion (DLI), and then was treated with Avapritinib, one's RUNX1::RUNX1T1 fusion achieved continuously negative after 1 month treatment of Avapritinib, the other's achieved continuous negative after 7 months treatment of Avapritinib. One patient was treated with Avapritinib after DAC and DLI as preemtive intervention, and RUNX1::RUNX1T1 fusion did not turn negative, but the relative value of RUNX1::RUNX1T1 fusion was lower than before and lived stable for more than 10 months. Conclusions: Avapritinib is safe and effective in the prophylactic and preemptive treatment of AML with KIT mutation after allo-HSCT in children, which provides a clinical drug for the prevention of relapse after transplantation.

Analysis of CD58 As a Predictive Marker of Morphologic Response to Inotuzumab Ozogamicin in Patients with B-Cell Acute Lymphoblastic Leukemia

BACKGROUND Clinical outcomes for B-cell Acute Lymphoblastic Leukemia (B-ALL) have significantly improved in the last decade, owing to the introduction of newer agents such as inotuzumab ozogamicin (INO) and blinatumomab. Both of these antibody-based therapies are effective in adults with relapsed or refractory (R/R) B-ALL and have shown promising results in the frontline setting as well. Given the utility of these therapies, there have been efforts to identify predictive markers for these treatments in B-ALL patients. Recently, CD58 was identified as a modulator of response to blinatumomab due to its role as a CD2 ligand in T-cell activation (Li et al. Sci Adv 2022). This costimulatory relationship between CD58 and CD2 has also been linked to Natural Killer cell mediated lysis, which has been described as a mechanism of action of INO (Fu et al. Signal Transduct Target Ther 2022; Huntington et al. Nat Rev Cancer 2020). In this study, we evaluated the correlation of CD58 expression with achievement of morphologic Complete Remission (CR) or Complete Remission with incomplete blood count recovery (CRi) after treatment with INO. METHODS Retrospective chart review was performed to identify patients in our institution's B-ALL database who received INO between 09/15/2011 and 03/10/2023 with blood or bone marrow samples available for flow cytometry analysis prior to INO infusion. Because all patients had measurable CD58 expression by flow cytometry, mean fluorescence intensity (MFI) was used instead of percent positivity to perform a simple logistic regression analysis to evaluate the relationship between CD58 MFI and achievement of CR/CRi after treatment with INO. We then calculated the odds of achieving CR/CRi by age, molecular risk at diagnosis, and R/R disease status. Two patients lacked diagnostic cytogenetic data. Molecular risk stratification and assessment of morphologic response were performed according to National Comprehensive Cancer Network (NCCN) guidelines. To account CD58 MFI outliers, we then confirmed our results by comparing response rates between patients with a CD58 MFI above our median (CD58 MFI-high) to patients with a CD58 MFI below our median (CD58 MFI-low) using Fisher's exact test. RESULTS We found 34 patients who met our criteria for analysis, 2 of which had previously received INO (Table1). Median Overall Survival (OS) was 21.5 months (range, 1-58) with a median leukemia-free survival (LFS) of 13.5 months (range, 1-52). Response rates after INO were high, including 28 patients (82.4%) achieving CR, 30 patients (88.2%) achieving CR/CRi, and 27 patients (79.4%) achieving Measurable Residual Disease (MRD) negativity. Both patients with a history of prior treatment with INO attained CR with MRD negativity. The chi-square test statistic for our simple logistic regression model was not statistically significant (Figure1, p=0.915). The logistic regression coefficient showed no statistically significant association between CD58 MFI and CR/CRi rates after treatment with INO ( p=0.913). Our model predicted an 88.6% probability of achieving CR/CRi for a CD58 MFI of 8,727.97 (Q1), 88.4% for 11,719.88 (Q2), 88.0% for 19,622.85 (Q3), and 85.7% for 55,217.74 (Q4). There was no statistically significant difference in the odds of achieving CR/CRi in patients with poor molecular risk at diagnosis (OR=0.06, 95% CI [0.01, 1.22]), age &amp;gt;35 years (OR=2.75, 95% CI [0.33, 22.9]), or R/R disease (OR=0.98, 95% CI [0.01, 1.97]). When comparing response rates between CD58 MFI-high and CD58 MFI-low patients, each group contained 15 patients that achieved CR/CRi and 2 patients with refractory disease. This confirmed an equal response rate to INO between CD58 MFI-high and CD58 MFI-low patients ( p=1.000). CONCLUSION Overall, we did not find a statistically significant correlation between CD58 MFI and achievement of CR/CRi. Our study is limited by our small sample size, single-center location, and retrospective design. However, it is important to note the high rates of CR/CRi that were seen, regardless of the intensity of CD58 expression. Further work is needed to evaluate the role of CD58 as a predictive marker for other therapies in B-ALL. These data suggest that INO is likely to remain an effective option for these patients, regardless of the intensity of CD58 expression.

JAK2 Kinase Fusion and Myeloid Involvement in Acute Lymphoblastic Leukemia

Introduction JAK2 fusion genes (FGs) are rare but can be found in various phenotypes of myeloid or lymphoid malignancies. Both in the 5th edition of the World Health Organization Classification of Haematolymphoid Tumors (WHO-HAEM5, PMID: 35732831) and the International Consensus Classification (ICC, PMID: 35767897), JAK2-FGs were included in the diagnostic entity of myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions (MLN-TK or MLN-eo), and both suggest MLN-TK/eo as a priority diagnostic entity. It is highlighted in ICC that cases presenting as acute lymphoblastic leukemia (ALL) with M/LN-eo differ from de novo B-ALL and T-ALL in the involvement of myeloid cells. There is still a lack of research reports about how many JAK2-FG-positive ALL cases developed from M/LN-eo or had myeloid involvement. Methods A total of 21 ALL cases (Table 1) were enrolled in this study. The positive for JAK2-FGs were determined by G-banding karyotype analysis, transcriptome sequencing (RNA-seq; PMID: 34135310), reverse transcription PCR (RT-PCR), and interphase fluorescence in situ hybridization (I-FISH) with the JAK2 break-apart probe. Gene mutation analysis (PMID: 29932212) was also performed. According to whether there were FISH-JAK2 split signals in rod and lobed nuclear cells (Figure 1A), the cases were divided into My+ group (with myeloid involved) and My- group (without myeloid involved), respectively. Results Among these cases, there were 14 males and 7 females (M:F = 2:1); 15 B-ALL and 6 T-ALL cases; the median age was 22 years old (range 5-55). All cases were positive for JAK2-FGs in RNA-seq analysis, and all FGs were verified by RT-PCR and Sanger sequencing. A total of 16 JAK2 partner genes were detected (Table 1, Figure 1B/C), of which FNBP1, CDK5RAP2, GTF2I, and C14orf 93 have not been reported previously. All cases retained the complete kinase domain of the JAK2 gene, and 13 cases retained part or all of the JAK2 pseudo-kinase domain in their JAK2-FGs. Karyotype abnormalities were detected in 17 cases (81%), with 9p24 involved in 10 cases (48%), abnormalities other than 9p24 were observed in 7 cases, and karyotype was normal in 4 patients. FISH-JAK2 inspection showed split signals in 20 cases and showed negative results in case #21 who with a complex karyotype abnormality. Twelve cases (12/20=60%) showed JAK2 split signals in rotundum, rod, and lobed nuclei (Table 1, My+ group), suggesting both lymphoid and myeloid lineages were involved. We further investigated samples of 4 cases at the time of morphological complete remission after induction chemotherapy, of which the immunophenotype analysis was also negative for lymphoid blast cells. FISH-JAK2 inspection showed split signals accounting for 13%~79% of the nucleus, with split signals in the rod/lobed nucleus, and RT-PCR also confirmed abundant JAK2-FG transcripts in these samples. There were 8 B-ALL and 4 T-ALL cases in the My+ group, of which 2 T-ALL cases were also positive for STIL::TAL1 fusion, and 3 cases experienced eosinophilia during the course of the disease (Table 1). The 5 cases whose JAK2 partner genes were lymphoid development-related transcription factors (ETV6, PAX5) were all in the My- group. All My- cases and #21 had no documented eosinophilia. Among the 21 cases in this cohort, 13 had white blood cell (WBC) counts &amp;gt;50×10 9/L at diagnosis, and no significant hepatosplenomegaly. The total follow-up time was 2-89m, with a median overall survival (OS) time of 17m. Fourteen cases underwent allo-HSCT, and the median OS was 29.5m in the HSCT group and 9m in the non-HSCT group, respectively. The median OS was 15.5m in the My+ group and 29m in the My- group. The leukemia cells in these cases are prone to be in a high and rapid proliferation state, and they generally have a short OS and dismal prognosis. Conclusions Myeloid involvement accounted for 60% of JAK2-FG positive ALL and My+ cases had a worse prognosis and shorter OS than My- cases in this study. I-FISH inspection can be used as a method to determine whether there was myeloid involvement and provide valuable information for accurate analysis. The incidence of JAK2-FGs is low in ALL, but the fusion partners are diverse. This group of cases is more likely to have cryptic JAK2 translocations and with dismal prognosis. The phenotype of JAK2-FG malignancies is jointly determined by multiple factors under the influence of partner genes, accompanying fusion genes, and accompanying mutations.