Morphologic Complete Remission Research Articles

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 >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 >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.

Acute Leukemias of Ambiguous Lineage Have Durable Response to Hypomethylating Agents Plus Venetoclax in Older Patients

Background: The standard of care for frontline therapy of acute leukemias of ambiguous lineage (ALAL) remains controversial due to their rarity; however, outcomes are generally poor. Intensive chemotherapy (IC) regimens are standard, with evidence suggesting that acute lymphoblastic leukemia regimens are more effective than those used for acute myeloid leukemia (AML). Strategies for treating older or frail patients are limited. Although treatment with a hypomethylating agent plus venetoclax (HMA/Ven) is standard therapy for IC-ineligible AML patients, the role of HMA/Ven in ALAL remains poorly characterized. We performed a retrospective chart review of patients at our institution with Philadelphia-negative ALAL, comparing the outcomes of those treated with HMA/Ven and those who received IC. Method: Patients ≥ 18 years treated at Weill Cornell Medical Center with newly diagnosed, pathologically confirmed acute undifferentiated leukemia (AUL), T/myeloid, or Philadelphia chromosome-negative B- and B/T-myeloid leukemia were included. Frontline HMA/Ven was defined as Ven plus azacytydine, decitabine, or oral decitabine/cedazuridine (one patient had initial HMA monotherapy followed by HMA/Ven). Intensive chemotherapy included patients who received variations of standard ALL or AML IC regimens (hyper- or mini-hyper-CV[A]D, cytarabine plus daunorubicin or idarubicin, or cladribine plus idarubicin and cytarabine) with or without Ven. Tyrosine kinase inhibitors including midostaurin or gilteritinib were added for patients with fms-like tyrosine kinase 3 ( FLT3) mutations. Baseline and disease characteristics were collected as well as disease response, subsequent lines of therapy, whether the patient proceeded to allogeneic hematopoietic cell transplantation (HCT), rate of morphologic complete remission (CR), and overall survival (OS). Results: Of 16 patients, 7 received frontline HMA/Ven. B/myeloid was the most common disease type (n=8), followed by T/myeloid (n=4), AUL (n=3), and 1 patient with B/T/myeloid disease. The median age was 74 years (interquartile range [IQR] 62-80). Patients who received HMA/Ven were older than those who received IC, with median ages of 79 (IQR: 77-82) and 62 (IQR: 56-70; p = 0.01), respectively. Baseline white blood cell, hemoglobin, platelet counts, and lactate dehydrogenase, as well as blast percentages in both peripheral blood and bone marrow were similar between the groups. Although not validated in ALAL, markers of adverse myeloid disease as per the ELN 2022 schema were prevalent in both groups, including mutations in RUNX1, ASXL1, SRSF2, and TP53 (Figure A). One HMA/Ven patient and 3 IC patients underwent HCT. Of evaluable patients, 83% and 88% of HMA/Ven and IC patients achieved CRs, respectively. At 2 years, both groups had 50% overall survival (95% CI 22.5-100 in both). Among HMA/Ven recipients, overall survival ranged from 10-56 months, not including two patients with ongoing follow-up at 3 and 46 months (Figure B). Discussion: The treatment of ALAL remains a challenge, particularly in older patients who may be unfit for intensive treatment strategies. In our study, patients who received HMA/Ven had similarly durable disease control to younger patients who received IC in the frontline setting. Prolonged responses were seen in both AUL and MPAL. Multicenter registry and prospective analyses are needed; however, given the rarity of these diagnoses, our findings suggest that HMA/Ven should be considered as a frontline therapy for unfit patients with ALAL.

Venetoclax+Azacytidine Followed By Modified BuCy Conditioning Regimen for High Risk or Refractory/Relapsed Acute Lymphoblastic Leukemia and High Risk Myelodysplastic Syndromes

Background:Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only potential curable treatment for myelodysplastic syndromes (MDS) and acute lymphoblastic leukemia (ALL). However, for patients with high-risk or refractory relapsed (R/R) B-ALL with allo-HSCT, the three-year overall survival (OS) rate is only 5-10%, more worse in T-ALL. It is widely known that MDS patients in the high-risk group do not benefit from induction chemotherapy, the five-year OS rate is 23-39% when they received allo-HSCT. Nevertheless, relapse remains a significant cause of treatment failure after allo-HSCT, highlighting the urgent need for improved conditioning regimens that can improve prognosis and reduce relapse rates. Azacytidine (AZA) combined with Venetoclax (VEN), showed a synergistic anti-tumor activity against several hematological malignancies, Therefore, we explored AZA+VEN (VA) combined with modified BuCy(mBuCy) (semustine, cytarabine, busulfan, and cyclophosphamide) conditioning regimen and assessed the safety and effectiveness. Aims ：The aim of this study is to assess the safety, and effectiveness of the VA treatment regimen followed by mBuCy as conditioning regimen for high-risk or R/R ALL(NCT05809167) and high-risk MDS(NCT03256071) . Methods:Patients diagnosed with high-risk or R/R ALL or high-risk MDS (IPSS-R score), undergoing VA+mBuCy as conditioning regimen, and consolidation treatment with demethylating drugs every three months after transplantation, for a total of 8-12 cycles. Results:Patients diagnosed with high-risk or R/R ALL(n=11) or high-risk MDS (IPSS-R score)(n=8) were enrolled between January 13, 2022, and June 9, 2023. The ALL cohort comprised of 5 Ph-negative B-ALL, 2 Ph-positive B-ALL, 3 mixed phenotype leukemias (MPAL), and one T-lymphoblastic lymphoma/leukemia (T-ALL/LBL). There were 7 males and 4 females, with a median age of 33 years (17-54 years) (Table 1). Out of the eleven patients, four had previously undergone Chimeric Antigen Receptor T-Cell Immunotherapy (CAR-T) therapy, and one patient had received Blinatumomab. One patient experienced relapse, another patient was refractory, and 3 patients had extramedullary infiltration. All patients achieved morphological complete remission prior to transplantation, and 10 patients (90.9%) achieved a MRD negative remission. Additionally, all the transplantations successfully completed, with a median time to absolute neutrophil counts (ANC) recovery of 12 days (11-15 days) and platelet (PLT) recovery of 16 days (15-21 days). The median follow-up time was 6.4 months (2.4 -13.6 months), no patient experienced relapse or death, the OS and DFS are both 100%. There were no grade 3 or higher adverse events (AEs), hepatic veno-occlusive disease (VOD),and the transplant-related mortality (TRM). Four patients who developed acute graft-versus-host disease (aGVHD) post-transplantation, all cases involved grade I/II skin aGVHD, and one of them involved grade III GI aGVHD, and no chronic graft-versus-host disease (cGVHD) were observed during the follow-up period. By the endpoint of follow-up, Cytomegalovirus (CMV) activation was 45.4% (5/11) and Epstein-Barr virus (EBV) activation was 27.3% (3/11). The MDS cohort consisted of 7 cases of MDS-EB-I, 1 case of MDS-EB-II. There were 5 males and 3 females, with a median age of 42 years (23-57 years)(Table 2). Two patients received chemotherapy before transplantation, and the other six patients directly received allo-HSCT. In MDS cohort, the median recovery time for ANC was 12 days (11-13 days) and PLT was 17.5 days (16-20 days). The median follow-up was 14.3 months (1.2-18.3 months), no patient had relapsed or died, both OS and DFS are 100%. There were no grade 3 or higher AEs, and TRM. One patient developed VOD. Three patients developed aGVHD after transplantation, all involving degree I/II skin aGVHD, and there was one case of cGVHD during the follow-up period, where the patient developed a mild pulmonary cGVHD. By the endpoint of the follow-up, the rate of CMV activation was 37.5% (3/8) and EBV activation was 25% (2/8). Conclusion:The VA combined with the mBuCy proves to be a effective and safe conditioning regimen for high-risk ALL and MDS patients. However, more patients are needed for follow-up and validation.

Itacitinib for Prevention of Graft-Versus-Host Disease and Cytokine Release Syndrome with T-Cell Replete Peripheral Blood Haploidentical Transplantation

Introduction: Haploidentical peripheral blood allogeneic hematopoietic cell transplantation (PB haplo-HCT) can be complicated by graft-versus-host disease (GVHD) and cytokine release syndrome (CRS). Acute GVHD rates are higher with PB grafts compared with bone marrow, affecting 35-45% of patients and outcomes are poor in steroid refractory cases. Severe CRS occurs in 10-15% of patients receiving PB haplo-HCT and is associated with high non-relapse mortality and one-year overall survival between 25-30%. As interferon-γ and IL-6 are important mediators in both acute GVHD and CRS, we hypothesized that JAK1 inhibition with itacitinib could prevent these toxicities without impairing engraftment. Here we report outcomes from our study of itacitinib with haplo-HCT (NCT03755414). Methods: Patients with AML, MDS, ALL, or NHL in remission undergoing PB haplo-HCT were treated with itacitinib 200 mg/day on days -3 through +100 (first 20 patients) or 180 (second 22 patients), followed by a taper. Myeloablative and reduced intensity conditioning were allowed. GVHD prophylaxis was tacrolimus, mycophenolate mofetil, and post-transplant cyclophosphamide. Primary outcomes were incidence of primary graft failure and incidence of grade III-IV acute GVHD. Secondary outcomes included incidence and severity of CRS, relapse, GRFS, and overall survival. Results: Forty-two patients were enrolled and underwent transplantation on study between November 2019 and December 2022, median days of follow up was 453 days (range 142-1259). The patient population had a median age of 60 years (20 - 73 years) with the majority of patients having AML (AML 60%, ALL 21%), MDS 10%, MF 5%, NHL 4%). All patients with AML, MDS, or ALL were in a complete morphologic remission, although 45% had disease by either cytogenetics, next generation sequencing, or measurable residual disease assay (flow cytometry for AML/MDS, NGS for ALL). There were no cases of grade III-IV acute GVHD. The cumulative incidence of grade II acute GVHD on day 100 was 17.3% (95% CI, 7% - 31%), day 180 was 20.5% and day 365 was 20.5%. There were no cases of severe CRS with 90% of patients having grade 1 CRS and 10% having no CRS. No anti-IL6R or steroid therapy was used. There were no cases of primary graft failure. The cumulative incidence of relapse at 1 year was 10% (95% CI, 3% to 22%) and at 2 years was 14% (95% CI, 5% to 29%). In patients who survived without relapse to day 100, the 1-year cumulative incidence of moderate or severe chronic GVHD was 5% (95% CI 1% - 17%). The refined GRFS at day +180 was 85% (95% CI 69% - 93%) and at day +365 was 79% (95% CI 62% - 89%). Overall survival at 180 days 87% (95% CI 72% - 94%) and at 1 year was 80% (95% CI 63% - 90%). Analysis of peripheral blood mononuclear cells at day +28, +60, and +100, revealed that patients on itacitinib, compared with control haplo-HCT patients, had lower numbers of CD4 and CD8 central memory T cells, lower numbers of CD4 and CD8 naïve T cells, and higher numbers of classical monocytes, nonclassical monocytes, and both myeloid and plasmacytoid dendritic cells. In itacitinib treated patients, T-cell subsets expressed lower LAG3 and PD-1 and higher TIGIT, while monocytes expressed higher HLA-DR, CD80, and CD86. Conclusions: Itacitinib with PB haplo-HCT was safe with low rates of acute and chronic GVHD, without increased risk of relapse or transplant related mortality. Severe CRS was not seen in this trial, and no anti-IL6 or steroid therapy was used. The addition of Jak inhibition to standard PtCy based GVHD prophylaxis was associated with encouraging rates of GRFS and OS on this pilot and expansion study. Patients on itacitinib have unique immune reconstitution characteristics both in terms of PBMC counts and signaling markers within subsets.

Comparable Outcome after Busulfan- or Treosulfan-Based Conditioning Regimen in Children Above 4 Years of Age with ALL Undergoing Allogeneic HSCT. Results from the Prospective International Forum-Trial

Purpose: Total body irradiation (TBI) has proved to be the “gold standard” as part of the conditioning regimen before allogeneic hematopoietic stem cell transplantation (HSCT) in pediatric patients with acute lymphoblastic leukemia (ALL). Its superiority over chemo-based conditioning was recently demonstrated in the prospective, international, randomized phase III study, which enrolled 417 patients beyond the age of 4 years transplanted for ALL in complete morphological remission (CR) from either matched sibling (MSD) or matched unrelated donor (MD) (Peters et al, JCO 2021, FORUM study; EudraCT: 2012-003032-22;ClinicalTrials.gov: NCT01949129). The use of either of the two protocol-prespecified chemo-conditioning regimens resulted in significantly worse EFS. Given the unavailability of TBI in some regions/centres and contraindications to TBI in individual patients, we here compare the outcomes of patients who received busulfan (BU) - based regimen vs of those who were given a treosulfan (TREO) - based conditioning in FORUM centres in both randomizing and non-randomizing countries in the years 2013-2018. Patients and methods: Patients ≤ 18 years at diagnosis (median age at HSCT 9.9 years, range 4-19.5), in CR pre-HSCT and with an MSD or MUD were assigned to myeloablative conditioning with fludarabine (FLU), thiotepa (THIO) and either BU or TREO according to country preference. Children transplanted from MSDs received cyclosporine A only as graft-versus-host disease (GvHD) prophylaxis, whereas recipients of MUD HSCT also received short-term methotrexate and anti-thymocyte globulin (ATG). Further details of the transplant procedure have been previously described (Peters C, et al. J Clin Oncol 2021). Results:In addition to the 193 patients from the randomizing countries, the FORUM trial included 115 additional children enrolled in countries where randomization could not occur (for legal or technical reasons). Overall, 180 vs. 128 patients received BU/THIO/FLU vs TREO/THIO/FLU, respectively. There were no differences about the patients' gender, age, and remission status and slight differences regarding donor, stem cell source and MRD status pre-transplant between the two cohorts of patients (see Table 1 for details). Patient's outcomes were updated as of February 20 th, 2023, and median follow-up was 4.2 years (range 0.3 - 9.1). There were neither differences between the 3-year overall survival (OS) (0.71±0.03 for BU/THIO/FLU vs 0.72±0.04 for TREO/THIO/FLU) nor event-free survival (EFS) (0.61±0.04 for BU/THIO/FLU vs 0.55±0.04 for TREO/THIO/FLU, p=NS). Three-year cumulative incidence of relapse (CIR) and non-relapse mortality (NRM) were 0.31±0.03 and 0.08±0.02 following BU/THIO/FLU and 0.36±0.04 and 0.09±0.03 following TREO/THIO/FLU, respectively (p=NS). Only one case of secondary malignancy was observed in the TREO cohort and one case of fatal liver veno-occlusive disease (VOD) in the BU group. No statistical differences were observed regarding the cumulative incidence of both aGvHD and cGvHD between the two groups; 3-year GFRS was almost identical (0.42± 0.04 in the BU/THIO/FLU group and 0.43±0.04 in the TREO/THIO/FLU cohort). There were no differences in OS, EFS, CIR, NRM and GFRS in either CR1 or CR2 patients between the two conditioning regimens. Furthermore, there were no differences in outcomes between countries. Patients given BU/THIO/FLU had a faster leucocyte, neutrophil and platelet recovery as compared to those prepared with TREO/THIO/FLU. Conclusion: Comparable long-term outcomes were observed after BU/THIO/FLU or TREO/THIO/FLU in children with ALL undergoing allogeneic HSCT included in the FORUM trial. Therefore, either of the 2 regimens may be effectively and safely used worldwide in patients > 4 years having a contraindication to or treated in centres/countries unable to deliver TBI.

Tagraxofusp Maintenance Post-Hematopoietic Stem Cell Transplantation Provides Long-Term Survival and Manageable Safety for a Patient with Blastic Plasmacytoid Dendritic Cell Neoplasm

Introduction:Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, clinically aggressive hematologic malignancy that commonly involves four major compartments: cutaneous, bone marrow/blood, lymph nodes, and central nervous system (CNS). Tagraxofusp (TAG) is a first-in-class therapy directed to CD123, a target expressed in BPDCN, and is the only drug approved to treat BPDCN in the US and EU. TAG has demonstrated high rates of durable response and bridge to allogeneic hematopoietic cell transplantation (allo-HCT)(Pemmaraju N et al NEJM 2019). Historically, patients that undergo allogeneic allo-HCT have been reported to have long-term remissions, particularly if transplanted while in complete response; however, ~50% of patients will relapse post-allo-HCT, and strategies are needed to minimize this risk. No clinical studies to date have been conducted to assess the rate of post-HCT relapse in patients who receive TAG maintenance therapy after allo-HCT. This case study reports on a patient who was successfully treated with TAG therapy after allo-HCT in a phase 2 trial (NCT04317781). Methods and Results: A 68-year-old woman with BPDCN underwent allo-HCT and was enrolled in a TAG post-allo-HCT maintenance trial at the MD Anderson Cancer Center in 2021. Therapy prior to allo-HCT included hydroxyurea and TAG + venetoclax + mini-HyperCVAD for 5 cycles. The patient was in morphologic complete remission with low positivity by flow cytometry (positive for minimal residual disease [MRD]) at the time of allo-HCT. After allo-HCT and prior to TAG maintenance therapy, the patient had persistent cytogenic abnormalities on a bone marrow next-generation sequencing (NGS) panel. The patient received TAG 9 mcg/kg for 3 days on a 28-day cycle after allo-HCT. The patient received TAG in the post-allo-HCT setting for a total of 16 cycles. At mid-treatment (post Cycle 6, prior to Cycle 7) with TAG, the disease was in complete remission, and the bone marrow NGS panel was negative for mutations (MRD negative). The patient did not experience any high-grade toxicity or capillary leak syndrome (CLS); the only toxicity observed was weight gain (Grade 0 per CTCAE), TAG was stopped for that cycle, and the event resolved. After Cycle 16, the patient withdrew consent due to the burden of traveling from another state. Bone marrow NGS testing was repeated prior to discontinuing study treatment, and the panel remained negative for MRD, with disease still in complete remission. Conclusions: This case report demonstrates a patient experiencing a clinically meaningful benefit with TAG maintenance therapy after allo-HCT. Both prolonged survival and manageable safety, in this case, highlight the feasibility of long-term TAG maintenance post-allo-HCT to control BPDCN.

Conditioning Impacts on Regulatory T-Cells (Tregs) in the Microenvironment of AML: Observations from the Phase 1 Cynk-001-AML-001 Trial

Introduction: Evidence shows that NK cells can exhibit potent anti-tumor activity against acute myeloid leukemia (AML). CYNK-001 is a CD56+CD3- enriched, off-the-shelf, allogeneic natural killer (NK) cell therapy expanded from placental CD34 cells. The use of recombinant IL-2 (rhIL-2) therapy has induced regression of tumors by stimulating the activation and proliferation of NK cells. Low dose RhIL-2 has been shown to selectively expand and enhance the expression of maturation markers on the surface of NK cells, making them more potent killers in vitro and in vivo. CYNK-001-AML-001 is a Phase I multi-dose study evaluating the safety, tolerability, and persistence of CYNK-001 with or without rhIL-2 in adults with primary or secondary acute myeloid leukemia (AML) in morphologic complete remission (CR) with minimal residual disease (MRD) or relapsed/refractory (R/R) AML Aim: To determine the safety and tolerability of rhIL-2 when added to CYNK-001 and assess the impact of rhIL-2 on CYNK-001 activity and persistence. Methods This Phase I, single-arm, dose escalation clinical trial (NCT04310592) enrolled patients 18-80 years with R/R AML or MRD-positive CR. Escalating doses of CYNK-001 cells were administered following a standard 3+3 design, with 2 separate arms (MRD+ and R/R AML). Cohort 4a enrolled MRD+ AML subjects, while cohorts 4b and 5b enrolled R/R AML subjects. Cohort 4a and 4b utilized a dose of 1.8 billion CYNK-001 x 3 doses of CYNK-001 without rhIL-2. Cohort 5b utilized same dose of CYNK-001 along with rhIL-2. The decision to administer rhIL-2 in cohorts 6a, 6b, 7a and 7b would be based on review of safety, efficacy, and translational data in Cohorts 5b. In cohort 5b rhIL-2 was administered at a dose of 6M IU on days 0,2,4,7,9,11 and 14. Cohort 4b was used as a comparator. Results Five patients in cohort 5b received rhIL-2. Treatment was well tolerated with no dose limiting toxicities (DLT's) being observed. Ten adverse events ≥ grade 3 were experienced. The commonest grade 3 AE's were raised AST (2/10) and ALT (2/10). Two grade 4 AE's were reported including febrile neutropenia and a pre-existing GVHD. In cohort 4b, 3 out of 6 patients achieved an objective response (3x MLFS) at day 28. No patient in cohort 5b achieved a response. While there was an apparent higher baseline blast count in cohort 5b which may have contributed to the differences, translational data demonstrated a surge in Tregs without enhancement of T helper or cytotoxic cells or NK cell reconstitution. In cohort 4a, one subject who received rhIL-2 (6MIU/dose) in error showed an increase in Tregs similar to cohort 5b. Conclusion Treatment with CYNK-001 in combination with rhIL-2 was well tolerated with no dose-limiting toxicities observed. However, this approach does not enhance CD4 helper T cells, CD8 cytotoxic cells or NK cell reconstitution, while stimulated proliferation of Tregs. CYNK-001 proliferation and persistence was not enhanced with rhIL-2 infusion. Based on these data, rIL-2 was excluded from subsequent cohorts in this study.

Idarubicin Versus Daunorubicin Versus Mitoxantrone for Induction Chemotherapy in Acute Myeloid Leukemia: Patient Registration Study of Turkish Society of Hematology-Acute Myeloid Leukemia Working Group

Introduction: Standard induction chemotherapy in newly diagnosed acute myeloid leukemia (AML) includes a combination of standard-dose cytarabine and an anthracycline (idarubicin [IDA], daunorubicin [DNR], or mitoxantrone [MXR]). Anthracycline selection is still not standardized, and the impact of anthracycline selection on survival and response in patients with adverse genetic risk is of interest. The study aimed to retrospectively compare the effectiveness of induction regimens with respect to anthracycline preference. Methods: The study population was recruited from the Turkish AML Registry project database based on documentation of newly diagnosed AML and induction chemotherapy with IDA, DAU, or MXR in combination with cytarabine. Patients diagnosed before 31 August 2022 were received typical “7 + 3” induction chemotherapy containing 3 days of IDA, DAU, or MXR. Results: The study included 317 newly diagnosed AML patients (median age 51; range, 18 - 79; 55.2% male). Of the patients, IDA was administered in 266 (83.9%), DNR in 42 (13.2%), and MXR in 9 (2.8%). The three anthracycline treatment groups were similar between age, gender, type of AML by the World Health Organization (WHO), and risk classification by 2017 European LeukemiaNet (ELN) when evaluated according to the baseline disease characteristics. At the time of diagnosis, although the median white blood cell levels were 19 x 10 9/L (0.4 - 355) in the IDA, 7.8 x 10 9/L (0.7 - 357.2) in the DAU, and 5.5 x 10 9/L (0.6 - 34) in the MXR therapy group (p = 0.019); the hemoglobin and platelet levels and bone marrow blast percentage were similar between the treatment groups. FMS-like tyrosine kinase-3 internal tandem duplication ( FLT3-ITD) (p = 0.561) and Nucleophosmin 1 gene ( NPM1) (p = 0.430) mutation frequencies were also similar between treatment groups. Morphological complete remission (CR) was documented in 65% of all evaluable patients. Among the patient groups, CR was 67.7% for IDA, 50% for DNR, and 55.6% for MXR (p = 0.081). In univariate analysis (Table 1), significant predictors of overall survival (OS) were age ≥60 years (p <0.001), acute leukemias of ambiguous lineage (p <0.001), presence of disseminated intravascular coagulation (DIC) (p = 0.012), and FLT3-ITD mutation (p = 0.018); no significant interaction was noted between NPM1 mutation and OS (p = 0.059). Additionally, when idarubicin was taken as a reference, there was no meaningful relationship between anthracycline type and OS (p values for daunorubicin and mitoxantrone were 0.145 and 0.356, respectively). In multivariate analysis (Table 1), age ≥60 years (p = 0.001), acute leukemias of ambiguous lineage (p = 0.007), and the presence of DIC (p = 0.040) remained significant. After a median follow-up of 29.8 months, 32.5% relapse cases were documented and similarly distributed among IDA (33.1%), DNR (31%), and MXR (22.2%) therapy groups (p = 0.771). During the same period, allogeneic hematopoietic stem cell transplantation (AHSCT) was documented in 10.9% and 26.2% of patients treated for IDA and DNR, respectively. No patient progressed to AHSCT in the MXR arm (p <0.001). In the study, 142 (44.8%) deaths were reported, and there was a 48.5%, 26.2%, and 22.2% mortality rate between the IDA, DNR, and MXR treatment groups, respectively. There was no significant difference in OS by anthracycline type in both the study cohort and age group <60 years (Figures 1A and 1B). There was also no significant difference in OS in patients with the adverse genetic risk group and <60 years age group with adverse genetic risk, according to 2017ELN (Figures 1C and 1D). The results may have been influenced by the number of patients in the treatment groups of the retrospective study and by differences in fitness levels that needed to be measured systematically. Conclusions: We are encouraged that our findings mostly agree with previously published studies and that IDA, DNR, and MXR offer comparable survival values in the research and the younger patient groups. In the future, the ever-changing treatment environment in patient groups with targetable mutations makes choosing the optimal anthracycline for induction chemotherapy in AML much more difficult.

Newly Dignosed Early T-Cell Precursor Acute Lymphoblastic Leukemia Successfully Treated with Venetoclax Combined with DA and IA Regime

Abstract Background: Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is a distinctive and extremely aggressive subtype of T-ALL. It is characterized by the aberrant expression of myeloid/stem cell antigens and the lack of Tlymphoid antigens including CD1a, CD4, CD5, and CD8. Currently, standard combination chemotherapy is still the mainstay of ETP-ALL treatment. However, the optimal management remains to be determined. ETP-ALL has low response rates to conventional chemotherapy and high relapse rates with a grim prognosis. Although some ETPALL patients achieved morphologic complete remission (CR), a more signifcant proportion maintained MRD positive. Under the traditional induction and intensifcation treatment strategy, the ETP-ALL group had worse long-term outcomes than the non-ETP-ALL group [1]. A recent preclinical study suggested that inhibition of B-cell lymphoma/leukemia-2 (BCL-2) might be a potential treatment option for patients with ETP-ALL [2]. Here, we present two cases of ETP-ALL clinical reactivity to venetoclax in combination with the IA regimen, providing a better bridge to allogeneic hematopoietic stem cell transplantation (allo-HSCT). Case 1 A 47-year-old female was diagnosed with ETPALL in October 2021. Flow cytometry analysis showed CD7,CD117,CD34,CD13,CD2,CD200,cyCD3 positive,suggestive of ETP ALL. Cytogenetic analysis was normal and molecular panel identified aberrations in TET, EP300 and EZH2. She then recived venetoclax plus DA regime（venetoclax, 100 mg d1, 200 mg d2, 400 mg qd d3-14；daunorubicin 40mg d1-3；cytarabine 100mg d1-5). A bone marrow biopsy after the 1st cycle revealed CR with minimum residual disease (MRD) 1.91% by flow cytometry. She then received 2nd cycle of venetoclax plus CAG treatment and got MRD negative. She received 2cycles of the same combination and remained in MRD-negative CR prior to proceeding with a reduced intensity haploidentical allo-transplantation. She is currently 1 years and 4 months post-transplant and in remission. Case 2 A 53-year-old man was diagnosed with ETP-ALL following bone marrow aspiration in August 2022. He presented with Leukopenia and anemia (WBC 2.53× 109 /L, HB 73 g/L, PLT 148 × 109 /L). Bone marrow biopsy revealed a hypercellular bone marrow with 80% lymphoid blasts, negative for MPO staining. The flow cytometry showed the immunophenotype of the lymphoid blasts (CD7+CD34+CD33+CD13+CD200+cyCD3+nTdT+), which were consistent with the immunophenotype of the ETP-leukemic cells. Cytogenetics revealed der(4)(q35).The molecular panel identified aberrations in CSF3R,DNMT3A,CCND3,CSF3R and WT1. Therefore, ETP-ALL was diagnosed. Initially, he received the first cycles of venetoclax combined with IA regimen (venetoclax, 100 mg d1, 200 mg d2, 400 mg qd d3-14;idarubicin 10mg d1-3,cytarabine 100mg d1-5), and CR was achieved this time. Then, he received a 3rd CAG therapy. Subsequently, he underwent hematopoietic stem cell transplantation (HSCT) successfully in December, and CR was still maintained at now 7 months after HSCT. Conclusion Combination therapy of venetoclax with IA regimen is an effective regimen for treating patients with ETP ALL.

Detectable Somatic Variants Using Next Generation Sequencing (NGS) Post Allogeneic Hematopoietic Cell Transplant (Allo-HCT) Predict for High Relapse Risk in Acute Myeloid Leukemia (AML) and Myelodysplastic Syndromes (MDS)

Introduction: NGS is increasingly being utilized to identify pathogenic somatic and targetable variants in patients with newly diagnosed AML and MDS. Patients with high-risk disease are typically recommended to undergo allo-HCT as consolidation, upon achieving morphological complete remission (CR). But, despite achieving hematologic CR, patients often have detectable somatic variants pre allo-HCT that predict for increased risk of disease relapse. Longitudinal monitoring of somatic variants via NGS at diagnosis, pre-allo-HCT and post allo-HCT can assist in prognostication and identify patients that remain at high risk of relapse despite allo-HCT. Methods: Patients with AML or MDS who underwent a first allo-HCT and completed NGS testing at day +100 between years 2016 to 2021 were identified from the transplant registry of Mayo Clinic in Florida. The primary aim of the study was to evaluate the prognostic impact of detectable variants via NGS at day +100 days post allo-HCT on the following outcomes: 1) overall survival (OS), 2) relapse, 3) progression-free survival (PFS), and 4) non-relapse mortality (NRM). Disease risk was assessed based on European Leukemia Network (ELN) 2022 risk classification for AML and Revised International Prognostic Scoring System (R-IPPS) for MDS. Baseline variables were compared between patients with and without mutation at day +100 days post allo-HCT using Wilcoxon rank sum test for continuous variables and Fisher's exact test for categorical variables. Kaplan-Meier (KM) method was used to estimate freedom from events at different time points and draw corresponding survival curves. Results: 105 patients who underwent allo-HCT for AML and MDS and completed NGS testing at day +100 were included in the study population. Median age of the study population was 63 years (22-74) and 58% were of the male gender. Median HCT comorbidity score (HCT-CI) and KPS Karnofsky performance score (KPS) were 3 (0-8) and 90 (60-100), respectively. Matched unrelated donor (50%) and peripheral blood stem cells (98%) were the most common donor and graft source, respectively. Median number of lines of therapy pre allo-HCT was 1(0-6) and 52 (50%) patients had detectable variants after completion of chemotherapy and prior to allo-HCT. Seventeen (16%) had detectable variants via NGS on day +100. Eleven (65%) of these 17 had variants pre-allo-HCT and amongst the 88 patients with no variants post allo-HCT, 41 (47%) had detectable variants pre allo-HCT. There was no significant difference in baseline characteristics between patients with detectable variants at day+100 versus those who did not except for a higher KPS in patients with no variants at Day +100 of 90 (60-100) vs. 80 (60-100) (p=0.003). At a median follow up of 1.4 years (0.1-5.5), presence of a variant at day +100 was associated with inferior 4-year OS (32% vs. 69%, p<0.001) and higher relapse risk (64% vs. 23%, p<0.001). In univariate models, a lower KPS and presence of variants post allo-HCT were significantly associated with inferior OS, high relapse risk and worse PFS. Presence of variants pre allo-HCT was associated with an inferior PFS but did not impact OS or relapse risk. In multivariate models, KPS remained significant for OS, PFS and NRM; presence of variants at day +100 post allo-HCT approached significance for OS (p=0.06) and PFS (p=0.08) and was significant for relapse risk (p=0.002) (Table1) (Figure 1). Data regarding longitudinal evolution of variants and impact of individual variants on long term outcomes will be included at the time of presentation. Conclusion: These results indicate that presence of detectable somatic variants at day +100 is associated with poor long-term outcomes and predicts for high risk of disease relapse. Longitudinal monitoring of somatic variants via NGS should be consistently incorporated in the management of patients with high-risk AML and MDS undergoing allo-HCT. Patients with detectable somatic variants post allo-HCT should be considered for additional intervention to mitigate relapse risk.

Measurable residual disease conversion rate with consolidation chemotherapy in acute myeloid leukemia

The rate of MRD clearance in AML with standard consolidation chemotherapy is not well defined. A multi-institution retrospective analysis was performed on 107 consecutively treated AML patients in morphologic complete remission with detectable MRD post-induction therapy who received standard chemotherapy consolidation. In response to standard intermediate/high-dose cytarabine consolidation therapy, 26 of 60 patients (43.3%) with MRD threshold of detection of at least 0.1% converted to MRD-negative status (undetectable with assay used), and 6 of 47 patients (12.8%) with MRD threshold of detection > 0.1% converted to MRD-negative status. Multivariable logistic regression for patients with MRD threshold of detection of at least 0.1% showed that, when controlling for age, ELN risk category, dose of cytarabine, and use of a combination agent, treatment with 1 cycle of consolidation cytarabine versus ≥2 cycles decreased the odds of conversion of AML to MRD-negative (OR = 0.24, 95% CI 0.07–0.85, p = 0.03).

Cox proportional hazards deep neural network identifies peripheral blood complete remission to be at least equivalent to morphologic complete remission in predicting outcomes of patients treated with azacitidine-A prospective cohort study by the AGMT.

The current gold standard of response assessment in patients with myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML), and acute myeloid leukemia (AML) is morphologic complete remission (CR) and CR with incomplete count recovery (CRi), both of which require an invasive BM evaluation. Outside of clinical trials, BM evaluations are only performed in ~50% of patients during follow-up, pinpointing a clinical need for response endpoints that do not necessitate BM assessments. We define and validate a new response type termed "peripheral blood complete remission" (PB-CR) that can be determined from the differential blood count and clinical parameters without necessitating a BM assessment. We compared the predictive value of PB-CR with morphologic CR/CRi in 1441 non-selected, consecutive patients diagnosed with MDS (n = 522; 36.2%), CMML (n = 132; 9.2%), or AML (n = 787; 54.6%), included within the Austrian Myeloid Registry (aMYELOIDr; NCT04438889). Time-to-event analyses were adjusted for 17 covariates remaining in the final Cox proportional hazards (CPH) model. DeepSurv, a CPH neural network model, and permutation-based feature importance were used to validate results. 1441 patients were included. Adjusted median overall survival for patients achieving PB-CR was 22.8 months (95%CI 18.9-26.2) versus 10.4 months (95%CI 9.7-11.2) for those who did not; HR = 0.366 (95%CI 0.303-0.441; p < .0001). Among patients achieving CR, those additionally achieving PB-CR had a median adjusted OS of 32.6 months (95%CI 26.2-49.2) versus 21.7 months (95%CI 16.9-27.7; HR = 0.400 [95%CI 0.190-0.844; p = .0161]) for those who did not. Our deep neural network analysis-based findings from a large, prospective cohort study indicate that BM evaluations solely for the purpose of identifying CR/CRi can be omitted.

Utility of end of induction bone marrow biopsy and survival outcomes in acute promyelocytic leukemia treated with fixed-dose induction regimen

Significant variations exist related to the end of induction practices in the management of Acute Promyelocytic Leukemia (APL). These variations include all-trans retinoic acid (ATRA)-arsenic trioxide (ATO) in fixed doses versus continuation until hematologic complete remission (CR) and performance versus omission of post-induction bone marrow biopsy to confirm morphological CR. A retrospective chart review was conducted of 61 patients (42 low/intermediate-risk and 19 high-risk) aged ≥ 18 years with newly diagnosed APL treated with fixed duration ATRA-ATO +/- cytoreduction at a tertiary medical center from December 2012 through March 2020. Of the 54 patients with post-induction bone marrow biopsy results, 52 (96%) demonstrated no morphologic evidence of APL while the remaining were equivocal. After 2.6 years median follow-up, no relapses occurred. The estimated 2-year overall survival rate of 95% suggests excellent outcomes with a fixed ATO induction regimen and safe omission of post-induction bone marrow biopsy irrespective of hematologic parameters.

Influence of conditioning regimen intensity on outcomes post-allogeneic hematopoietic cell transplantation for acute myeloid leukemia in complete morphological remission.

The literature comparing outcomes between myeloablative (MAC) and reduced intensity conditioning (RIC) for acute myeloid leukemia (AML) is conflicting. We retrospectively analyzed 451 patients who underwent allogenic hematopoietic cell transplantation (alloHCT) for AML in complete remission (CR) with either RIC (n = 331) or MAC (n = 120) with the use of dual T-cell depletion as graft-versus-host disease (GVHD) prophylaxis. Univariate analysis demonstrated nonrelapse mortality (NRM) at 2 years was 19.1% for MAC and 22.5% for RIC (p = .44). Two-year cumulative incidence of relapse (CIR) was 19.8% for MAC and 24.5% for RIC (p = .15). Two-year overall survival (OS) was 61% and 53% for MAC and RIC, respectively (p = .02). Two-year graft-versus-host disease relapse-free survival (GRFS) was 40.8% for MAC and 33.7% for RIC (p = .30). A propensity score-matched analysis was done matching patients for age, HLA match, in vivo T-cell depletion, and Disease Risk Index (DRI). Two-year OS was 67% for MAC, 66% for RIC (p = .95). A subgroup analysis identified that matched related donor transplants benefit from MAC with OS at 2 years 82.6% versus 57.3% for RIC (p = .006). In the matched-related donor setting, MAC regimens may offer superior survival. Overall, for our cohort of predominantly in vivo T-cell depleted patients the outcomes of MAC and RIC were similar.

Prognostic value of the mutation types and dynamics of FLT3-ITD in acute myeloid leukemia.

The prognostic value of the mutation types and dynamics of FLT3-ITD in acute myeloid leukemia (AML) and other known factors were studied. Initial and follow-up samples from 45 AML patients with FLT3-ITD mutations were analyzed by fragment length analysis, Sanger sequencing, and next-generation sequencing. Some patients (13%) had multiple FLT3-ITD mutations, and many of them had acute promyelocytic leukemia (APL). FLT3-ITD mutations were classified according to mutation types, including duplication-only FLT3-ITD (52%) and FLT3-ITD with duplications and insertions (dup + ins) (48%). The dup + ins FLT3-ITD variant was independently associated with poor prognosis among non-APL patients (odds ratio, 2.92) in addition to FLT3-ITD with ≥50% variant allele frequency (VAF). The VAFs of FLT3-ITD were low (median 2.2%) when detected during morphologic complete remission (CR) after conventional chemotherapy; however, in two patients treated with gilteritinib after relapse, the VAFs of FLT3-ITD were much higher (>95% and 8.1%) in the morphologic CR state. The type of FLT3-ITD mutation is important in prognosis, and the dup + ins type of FLT3-ITD can be an indicator of poor prognosis. In addition, the FLT3-ITD mutation status may unexpectedly not match the morphologic examination results after gilteritinib treatment.

Effect of disease status prior to T-cell depleted allogeneic stem cell transplantation on relapse-free and overall survival in patients with adverse-risk acute myeloid leukemia (AML).

7049 Background: Patients (pts) with adverse risk AML experience poor long term disease control. Some of these pts can be rescued with allogeneic stem cell transplantation (SCT). Adverse risk was defined by high risk cytogenetic and molecular markers (2017 European Leukemia Network criteria) and by disease status prior to SCT. We investigated outcomes of pts receiving in vivo T-cell depleted allogeneic SCT (TCD-SCT) at our center. Methods: We retrospectively analyzed 200 adverse-risk AML pts who received TCD-SCT from 2002-19. Pts were categorized into groups: untreated first relapse at SCT, primary induction failure with active disease at SCT, resistant to first induction but achieving morphologic complete remission (CR) by SCT, and induction sensitive CR with high-risk disease by ELN criteria. Outcomes were evaluated by 1-year (yr) and 3-yr relapse-free survival (RFS), overall survival (OS), and non-relapse mortality (NRM), and compared with log-rank tests of significance. Results: Baseline pt characteristics included a median age of 54 years (IQR, 44-61) with 62 (31%) pts older than 60, and 81 (41%) with HCT-CI score 3 or greater. All pts underwent in vivo TCD with alemtuzumab or ATG; 153 (77%) received reduced-intensity conditioning; 142 (71%) had 8/8 or 7/8 matched donors. Fourteen (7%) pts developed grade III-IV acute graft versus host disease (GVHD), and 25 (13%) developed chronic GVHD. With a median follow up of 14.3 months, cumulative incidence of relapse was 59% and NRM was 27%. Outcomes are summarized in the table. There was a statistically significant difference between categorized groups by RFS (p&lt;0.01) and OS (p&lt;0.01). Conclusions: We conclude that among adverse-risk AML pts, those in CR at time of TCD-SCT have superior survival outcomes to those with active disease. For those in CR at TCD-SCT, prior resistance to frontline induction was associated with inferior survival, suggesting that AML biology, treatment sensitivity, and remission status are important factors for TCD-SCT outcomes. The inferior outcomes observed for those with primary refractory disease suggest that while TCD-SCT can be effective with acceptable NRM, more work is needed to identify which pts can benefit from future transplant strategies. Better post-SCT therapy is needed to prevent relapses. [Table: see text]

NGS-defined measurable residual disease (MRD) after initial chemotherapy as a prognostic biomarker for acute myeloid leukemia

Treated AML patients often have measurable residual disease (MRD) due to persisting low-level clones. This study assessed whether residual post-treatment somatic mutations, detected by NGS, were significantly prognostic for subsequent clinical outcomes. AML patients (n = 128) underwent both pre-and post-treatment testing with the same 42-gene MRD-validated NGS assay. After induction, 59 (46%) patients were mutation-negative (0.0024 VAF detection limit) and 69 (54%) had ≥1 persisting NGS-detectable mutation. Compared with NGS-negative patients, NGS-positive patients had shorter overall survival (17 months versus median not reached; P = 0.004; hazard ratio = 2.2 [95% CI: 1.3–3.7]) and a shorter time to relapse (14 months versus median not reached; P = 0.014; HR = 1.9 [95% CI: 1.1–3.1]). Among 95 patients with a complete morphologic remission (CR), 43 (45%) were MRD-positive by NGS and 52 (55%) were MRD-negative. These MRD-positive CR patients had a shorter overall survival (16.8 months versus median not reached; P = 0.013; HR = 2.1 [95% CI: 1.2–3.9]) than did the MRD-negative CR patients. Post-treatment persisting MRD positivity, defined by the same NGS-based test used at diagnosis, is thus a more sensitive biomarker for low-level leukemic clones compared to traditional non-molecular methods and is prognostic of subsequent relapse and death.

PH negative acute lymphoblastic leukemia in adolescents and young adults treated according a MRD adapted BFM ALL IC 2009 protocol: Argentine real-world data on 171 patients.

Intensified pediatric chemotherapy regimens to treat adolescents and young adults (AYA) patients with Philadelphia negative acute lymphoblastic leukemia (ALL) have been associated with better outcomes. The local BFM 2009-based scheme complements the risk stratification assessing the measurable residual disease (MRD) along the induction phase with increasing levels of sensitivity. The present retrospective multicenter analysis included 171 AYA (15-40 years) patients treated accordingly between 2013 and 2019. Ninety-one percent obtained morphological complete remission, 67% a negative (<0.1%) MRD at day 33 (TP1), and 78% a negative (<0.01%) MRD at day 78 (TP2). The overall survival (OS) and the event-free survival (EFS) at 2 years were 62%±4.1 and 55%±4.1, respectively. The OS and EFS were significant better for prednisone responders, who achieved <10% BM blast at day 15, a negative MRD at TP1 or at TP2, and for low-risk patients. Age ≤30 years and WBC <30×109/L, particularly among B-phenotype, were also associated with longer OS. In the multivariable analyses, TP1 MRD positive (OS HR 2.8, 95% CI 1.4-5.7, p=0.004; EFS HR 3.0, 95% CI 1.6-5.7, p=0.001) and at TP2 (OS HR 2.6, 95% CI 1.3-5.3, p=0.012; EFS HR 2.6, 95% CI 1.3-5.1, p=0.006) were independently associated with earlier events. Age >30 years was also associated with a shorter survival (HR 3.1, 95% CI 1.3-7.5, p=0.014). Therefore, those 68 patients ≤30 years with TP1/TP2 negative MRD depicted a longer OS (2 years 85%±4.8). Based on our real-world data, the pediatric-based scheme is feasible in Argentina associated with better outcomes for younger AYA patients who achieved negative MRD at day 33 and 78.

Measurable Residual Disease (MRD) as a Surrogate Efficacy-Response Biomarker in AML

In acute myeloid leukemia (AML) many patients experience relapse, despite the achievement of morphological complete remission; therefore, conventional morphologic criteria are currently considered inadequate for assessing the quality of the response after treatment. Quantification of measurable residual disease (MRD) has been established as a strong prognostic marker in AML and patients that test MRD negative have lower relapse rates and better survival than those who test positive. Different techniques, varying in their sensitivity and applicability to patients, are available for the measurement of MRD and their use as a guide for selecting the most optimal post-remission therapy is an area of active investigation. Although still controversial, MRD prognostic value promises to support drug development serving as a surrogate biomarker, potentially useful for accelerating the regulatory approval of new agents. In this review, we will critically examine the methods used to detect MRD and its potential role as a study endpoint.