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Abstract E1910 evaluated the addition of blinatumomab to chemotherapy in adults with B-acute lymphoblastic leukemia (ALL). The addition of blinatumomab in patients (pts) with measurable residual disease (MRD) negative (neg) B-ALL significantly improved both relapse-free and overall survival (NEJM 2024; 391: 320-33)1. Given the increasing use of blinatumomab and the E1910 backbone chemotherapy regimen, we evaluated > Grade 3 toxicities on this trial in further detail. We assessed toxicity among the MRD-neg pts by age, gender, body mass index (BMI), combined cytogenetic-molecular risk, and number of cycles of blinatumomab received. We also evaluated toxicities during induction since this trial used a modified chemotherapy backbone. Methods: The eligibility, combined cytogenetic-molecular risk, and treatment have been previously described.1 All toxicities were > Grade 3 by CTCAE version 4 with at least a possible relationship to treatment. Descriptive statistics were used to summarize the occurrence and rates of toxicities and Fisher's exact test was used to compare differences in proportions between groups. Analysis of induction included all pts who started treatment. Analysis of Step 3 toxicities included MRD-neg pts who started treatment on the blinatumomab (n=111) or chemotherapy only arm (n=112). Results: Pt characteristics: For induction (n=488), median age was 51 years (yrs) (range 30-70); 48.6% female. Combined cytogenetic-molecular risk: favorable (13.5%); intermediate (12.9%); no risk assigned (16.2%); unfavorable (57.4%). For induction, we compared toxicities for E1910 (n=488) to pts treated on a prior young adult study (n=289) (C10403) (Blood Adv 2021; 5(2): 504-12). The incidence of hyperglycemia (8% vs. 31.1%, p< 0.001), aspartate aminotransferase (AST) increase (6.1% vs. 12.8%, p=0.002), alanine aminotransferase increase (ALT) (11.7% vs. 28.7%, p< 0.001), and hyperbilirubinemia (11% vs. 19%, p=0.002) were significantly lower in E1910 pts. The incidence of pancreatitis (1.8%), thromboembolic events (4.5%), and febrile neutropenia (25.4%) in E1910 was similar to C10403. Toxicities in the MRD-neg pts in the blinatumomab arm (n=111): Despite a high incidence of neutropenia (74.8%) and thrombocytopenia (55.9%) in Step 3, there was a relatively low incidence of sepsis (7.2%), bacteremia (1.8%), cytokine release syndrome (CRS) (3.6%) and neurologic adverse events (0-6.3%). There was a higher incidence of neurological or psychiatric events in the blinatumomab arm (23%) versus chemotherapy arm (5%) (p < 0.001) when all events were combined. There was a numerically higher incidence of ataxia (4.4% vs. %, p=0.16) and dysphasia (11.1% vs. 3%, p=0.12) in pts > 55 yrs and a higher incidence of neutropenia (80.3% vs. 66.7%, p=0.12) and thrombocytopenia (62.1% vs. 46.7%, p=0.12) in the younger pts (age < 55 yrs). In pts with a BMI < 30 kg/m2 (vs. > 30 kg/m2), there was a significantly higher incidence of leukopenia (51.7% vs. 26.4%, p=0.007) and thrombocytopenia (65.5% vs. 45.3%, p=0.037). However, this did not translate into an increased incidence of bleeding or infectious complications. By gender, females had a higher numerical incidence of AST increase (8.8% vs. 0%, p=0.057) and CRS (7% vs. 0% p=0.12); whereas males had a higher incidence of catheter- related infections (7.4% vs. 0%, p=0.05) and hyperglycemia (11.1% vs. 3.5%, p=0.16). A little more than half (56.8%) of pts received 4 cycles of blinatumomab with the remainder of pts receiving 1 (10.8%), 2 (28.8%), or 3 cycles (3.6%). Pts receiving 3-4 cycles of blinatumomab vs. 1-2 cycles of blinatumomab had a statistically higher incidence of anemia (38.8% vs. 6.8%, p< 0.001), neutropenia (98.5% vs. 38.6%, p< 0.001), and thrombocytopenia (83.6% vs. 13.6%, p< 0.001), likely related to being on treatment for a longer period of time. Conclusions: Blinatumomab was well tolerated with no significant toxicity differences noted by age, gender, or number of cycles of blinatumomab received. Pts with a lower BMI did have an increased incidence of leukopenia and thrombocytopenia, possibly related to flat dosing of the drug. However, this did not translate into increased complications. Toxicites during induction were notably few, which suggests that this backbone with age adjustments may serve as a good backbone for future trials. Blinatumomab is being evaluated with low dose chemotherapy and other targeted agents in ongoing trials.

Abstract Introduction:A comprehensive integration of significantly mutated genes and pathways with molecular subgroups is lacking in adult B-ALL. Furthermore, the genomic drivers underlying each subgroup remain to be identified.We aimed to perform genomic analysis on a large cohort of patients with adult B-ALL, and to correlate genomic markers with achievement of MRD negativity enabling blinatumomab randomization, and with subsequent response to blinatumomab. Methods:For genomic analysis, we studied 569 adults with newly diagnosed B-ALL registered for initial screening on the ECOG-ACRIN-led E1910 trial (NCT02003222), which evaluated the addition of blinatumomab to standard consolidation chemotherapy. The median age was 52 yrs (range 30 to 71 yrs), with 52% males. Analysis was performed on tumor and matched-normal samples using whole transcriptome sequencing (RNA-seq; tumor only; n=569), whole exome sequencing (n=490), whole genome sequencing (n=131), and single nucleotide polymorphism array (n=445). B-ALL cases were classified into 22 molecular groups. Outcome analysis was limited to patients enrolled and treated on E1910 (n=319). Results: Driver genes (n=268) were identified by the mutation-significance detection tool dNdScv or by the presence of pathogenic variants in known cancer genes, with NUP188 identified as a novel driver gene. Recurrently mutated pathways included: B-cell development (46%), cell cycle (44%), epigenetic regulation (30%), other transcriptional regulation (27%), Ras signaling (25%), RNA machinery (17%) and JAK-STAT signaling (8%). A high frequency of high-risk subtypes was observed including BCR::ABL1 (20%), BCR::ABL1-like (18%), low hypodiploid (14%) and KMT2A (12%). Using tSNE analysis, we identified a new cluster of cases (n=20, 3.5%) lacking a known subgroup driver, with overexpression of CEBPA (n=13) or CEBPB (n=7), distinct from CEBPE/ZEB2, termed “CEBP-altered” ALL (CEBPalt). Five of 13 cases with high CEBPA expression harbored an IGH::CEBPA rearrangement and one harbored a RXRA::CEBPA enhancer hijacking alteration. Of the 7 cases with high CEBPB expression, 5 harbored IGH::CEBPB, and two of these had concomitant clonal BCR::ABL1 fusions. To identify additional mechanisms of CEBP deregulation, in situ Hi-C coupled to H3K27 acetylation immunoprecipitation (HiChIP) was performed on 5 cases. Four cases showed evidence of de novo CEBPA enhancer activity. In two cases, we identified novel insertions (12 and 34nt) ~2kb downstream of CEBPA. A novel translocation and enhancer hijacking event between LINC00426 and the 5' UTR of CEBPB was identified in the remaining case. Overall, we confirmed genomic alterations of CEBPA or CEBPB in 16 of 20 cases with available material. Thus, we have identified a new molecular subgroup of adult B-ALL characterized by genomic alterations that drive enhancer hijacking and oncogenic deregulation of CEBPA/CEBPB. Several subgroups were enriched in patients that failed induction chemotherapy (n=62) or were MRD-positive (n=63) compared to those that achieved MRD-negative status (n=194): BCR::ABL1-like (30 vs 14%, p<0.001), KMT2A (18 vs 9%, p=0.03) and BCL2/MYC (5 vs 1%, p=0.06). Conversely, the following subgroups were enriched in patients that achieved MRD-negativity: PAX5alt (6 vs 18%, p=0.002), TCF3::PBX1 (0 vs 5%, p=0.01) and ZNF384 (2 vs 6%, p=0.08) Within each molecular subgroup we compared the survival of patients who achieved MRD-negative status after induction and were randomized to receive blinatumomab plus chemotherapy (n=93) or chemotherapy only (n=91). Although numbers were low, blinatumomab improved relapse-free survival for patients with hyperdiploid, PAX5alt, BCR::ABL1-like and KMT2A ALL compared to chemotherapy alone. Clonal hematopoiesis of indeterminate potential (CHIP)-related gene mutations were identified in 121 of 417 cases analyzed (29% total: somatic 74%, remission 31%, both 5%). TP53 mutations were most frequent (n=65 patients), with the majority identified in patients with low hypodiploid (n=52). Interestingly, patients with CRLF2 rearrangements collectively harbored the highest number of other CHIP gene mutations (n=13), including DNMT3A (n=4), TET2 (n=3) and ASXL1 (n=3). Conclusions:We provide a comprehensive landscape of genomic alterations in adult B-ALL and identify a new group characterized by deregulation of CEBPA/CEBPB (CEBPalt). We also provide insights into the efficacy of blinatumomab in different molecular subgroups of adult B-ALL.

Abstract Background: The addition of the CD19/CD3 bispecific T-cell engager, blinatumomab, to standard consolidation chemotherapy in adults with ALL who achieved a measurable residual disease negative (MRDneg) remission (CR), demonstrated an improvement in 3-year overall survival (OS, 85% vs 68%, HR 0.41, P=0.002) and 3-year relapse-free survival (RFS, 80% vs 64%, HR 0.53) compared to conventional chemotherapy in the ECOG-ACRIN E1910 study (Litzow et al, NEJM 2024). Given the complex therapy in this study, treatment delays and modifications are expected. We herein explored the impact of such delays on patient outcomes. Methods: In the phase 3 ECOG-ACRIN E1910 trial (NCT02003222), adults aged 30-70 years with newly diagnosedALL who had achieved MRDneg CR following induction and intensification were randomized to consolidation chemotherapy with blinatumomab (blina arm) or chemotherapy alone (chemo arm). We examined the association between the timing of the initiation of maintenance therapy and OS and RFS. The expected duration of consolidation was 252 days vs 126 days for patients on the blina and chemo arms, respectively. For this analysis, participants were classified into two groups (no/short delay or long delay) depending on whether they started on time/before or after the median time between the beginning of consolidation and start of maintenance therapy for their treatment group (medians: 335 days, range, 181-457 days vs 176 days, range, 139-265 days for blina and chemo arms, respectively). Multivariate analyses of OS and RFS were performed to examine the effect of no/short delay vs. long delay in starting maintenance. Patients were stratified according to their assigned consolidation treatment arm, and the models were further adjusted for age, sex, white blood cell count, platelets, hemoglobin, peripheral blood blasts, bone marrow blasts, performance status and genetic-genomic risk at diagnosis. Results: Of the 488 patients enrolled, 224 MRDneg patients were randomized to consolidation chemotherapy with or without blinatumomab and 135 of the 224 went on to maintenance therapy on study (N= 66 on blina arm and 69 on chemo arm, respectively). The median follow-up from the time of maintenance registration was 43.4 months. There were no significant differences in baseline characteristics between patients in either arm who experienced no/short delay or long delay. In the blina group, 60 of 66 patients (90.9%) received all 8 cycles of consolidation therapy of which 31 (45.6%) had long delays. Sixty-eight of 69 patients on the chemo arm (98.5%) received all cycles of consolidation therapy, of which 34 (50%) had a long delay. Strikingly, patients who had a long delay before initiation of maintenance had a significant improvement in OS in multivariate analysis compared to patients who had no/short delay (HR 0.31, 95% CI: 0.11-0.91; P =0.03). However, within each treatment group, OS benefit did not reach statistical significance (blina arm: HR 0.04, 95% CI: 0.001-1.64; P =0.09; chemo arm: HR 0.32, 95% CI: 0.08-1.38; P =0.13). Similar results were observed for RFS in multivariate analysis (HR 0.40, 95% CI: 0.16-1.01; P =0.05), though this impact on improved RFS was noted in the chemo arm but not in blinatumomab treated patients (blina arm: HR 0.56, 95% CI: 0.10-3.24; P =0.52; chemo arm: HR 0.19, 95% CI: 0.04-0.83; P=0.03). Additionally, patients who had no/short delay before starting maintenance experienced a longer median duration of maintenance treatment (blina arm, 548 days; chemo arm, 708 days) compared to patients who had a long delay (blina arm 488 days; chemo arm 598 days) before initiation of maintenance (P=0.0008). Conclusion: In the phase 3 randomized ECOG-ACRIN E1910 clinical trial, long delays between initiation of consolidation therapy and start of maintenance therapy were associated with improved OS compared to no/short delays. However, within each treatment group (blina or chemo), no significant difference of OS was observed. We postulate that these longer delays allowed more patients to receive all of the recommended protocol-assigned therapy thereby resulting in improved survival. Furthermore, patients who had no/short delays had a significantly longer duration of maintenance therapy. These data indicate that treatment delays during consolidation do not worsen survival. Further studies are being done to better understand why patients with long delays had better overall survival.

Abstract SWOG 1318 evaluated the feasibility of combining the tyrosine kinase inhibitor (TKI) dasatinib with prednisone and blinatumomab in older patients (pts) with Philadelphia chromosome positive (Ph+) B-acute lymphoblastic leukemia (ALL). Here, we present longer follow up (median follow up 5.6 years) with outcomes, predictors of response, and translational medicine studies. Methods: This trial was activated through the NCTN in January 2014 and closed to accrual in April 2021. Pt eligibility included: age > 65 years, Ph+ ALL, no evidence of central nervous system (CNS) disease, and adequate organ function. Treatment has been previously described (Blood Adv 2023; 7(7): 1279-85). Statistics: Categorical and quantitative endpoints comparisons used Fisher's exact and Wilcoxon tests. Survival endpoints used the Kaplan-Meier method and Cox regression models and were landmarked for post-baseline events as needed (i.e., number of cycles). Translational medicine studies: Single cell ATAC seq (10x genomics) was performed on 9 archived cryopreserved diagnostic samples from patients with > 500,000 cells. All samples successfully completed library preparation, sequencing, and demonstrated adequate blast clusters for analysis. Briefly, cryopreserved cells were thawed, and transposases were introduced into nuclei in single cell suspension and used to generate GEM beads. ATAC seq libraries were prepared per manufacture instructions. Libraries were then sequenced on a 25B flow cell on Novaseq X plus (Illumina). The data were analyzed with cloupe (version 9.0.0). Results: Twenty-four eligible patients were enrolled. The median age was 73 years (range 65-87). All pts had newly diagnosed Ph+ ALL. Seventy-nine percent of pts had additional cytogenetic abnormalities. Twenty-two pts (92%) achieved a complete remission (CR) during dasatinib and prednisone induction therapy. Most sites also monitored patient's blood or bone marrow with real-time quantitative PCR to quantify the BCR-ABL1 transcript for molecular response. Of 19 patients analyzed 17 (89%) were in a major or complete molecular remission at some point after treatment, with at least 12 of these patients achieving complete molecular remission. Three patients remain on maintenance. The median follow up for patients who are alive is 5.6 years (range 4.4-8.3). Five- year OS and DFS estimates are 63% (95% CI: 40-78%) and 64% (95% CI: 40-80%). Two patients relapsed in the CNS. One pt proceeded to allogeneic hematopoietic stem cell transplant (HSCT) and 1 to autologous HSCT. Increased age was associated with a decreased chance of achieving CR as best response (median age in responder group 73.2 years [range 65-82.9]; median age in non-responder group 85.5 [range 83.8-87.3]; p=0.02). Patients with extramedullary disease had shorter DFS (HR 0.22, 95% CI 0.04-1.15, p=0.07). Increased number of cycles of blinatumomab received was associated with a trend towards improved OS (HR 0.66, 95% CI 0.41-1.08, p=0.10). Translational medicine studies for chromatin accessibility in the blast clusters demonstrated improved OS in patients with homogeneous blast clusters (HR 0.42, 95% CI 0.06-3.04, p=0.39), high DUX4 differential accessibility (HR 0.26, 95% CI 0.03-2.55, p=0.25), and ATAC seq data corresponding to decreased chromatin accessibility in HOXA2 (HR 0.09, 95% CI 0.01-1.05. p=0.06). Conclusions: Despite an elderly population, this trial demonstrated impressive outcomes with longer follow-up for patients with Ph+ ALL. The number of cycles of blinatumomab and the presence of extramedullary disease may be important factors in outcome. Translational studies suggest additional markers may be predictors of overall survival, and these will need to be studied on larger scale studies. Decreased chromatin accessibility to HOXA2 was associated with a trend towards improved OS. Additional translational medicine will also be presented at the meeting.

Introduction E1910 randomized pts with ALL aged 30-70 years who were measurable residual disease negative (MRD-) by multi-color flow cytometry (FC) after intensification to conventional chemotherapy (chemo) with or without blinatumomab (blina). The addition of blina resulted in improved overall survival (OS) (Litzow, NEJM 2024) and led to a new standard of care. Older ALL pts have inferior outcomes when compared to younger pts in part due to increased treatment toxicity. In E1910, exposure to dexamethasone and pegasparagase was reduced for older pts (age >55 years). We present results of subgroup analyses describing outcomes of older pts enrolled in E1910. Methods Details of the E1910 protocol remission induction (step 1), high dose methotrexate with pegaspargase intensification (step 2), blina randomization (step 3), and maintenance (step 4) or allogeneic hematopoietic stem cell transplant (HCT) were previously presented (Litzow, NEJM 2024). MRD status was determined after step 2 centrally with 6-color FC with MRD- defined as <0.01% in the bone marrow (BM). Following approval of blina in the US for MRD positive (MRD+) disease in 2018, MRD+ pts were assigned to the blina arm and no longer randomized. The primary objective was to compare the OS and relapse free survival (RFS) among older pts aged >55 years (pre-specified stratification factor) who received chemo + blina to that of pts who received chemo alone (step 3 treatment). Estimates of OS and RFS were calculated using the Kaplan-Meier method. Comparison of OS and RFS between treatment arms was conducted using the two-sided stratified log-rank test and Cox model with CD20 status, rituximab use, and whether pts intended to receive HCT or not as stratification factors. Stratified Multivariate Cox models of OS and RFS were used to further evaluate the effect of step 3 treatment, adjusted by gender, white blood cell count (WBC), platelets, hemoglobin, peripheral blood blasts, BM blasts, performance status and combined molecular risk category. Results Among the 488 enrolled pts, 211 were ≥55 years old with median age of 61 (range 55-70). Among older pts, 49.3% were female and 83.4% were white, 17 (8.1%) pts had WBC >30.000/uL at the time of diagnosis. 156 (73.9%) pts had CD10+ early B-ALL and 46 (21.8%) had CD10- B-ALL immunophenotype. The most common genetic subgroups were low hypodiploid (n=58, 27.5%), BCR::ABL1-like (n=34, 16.1%) and KMT2A rearranged (n=26, 12.3%). 8.1% of pts had low, 9.0% intermediate, 63.5% high combined molecular risk disease and in 19.4% of pts risk could not be assigned. Baseline characteristics were not significantly different in chemo + blina and chemo only pts. The median follow-up for this analysis from step 1 registration was 54.6 months. Complete response with (CR) or without (CRi) count recovery after induction was observed in 174 (82.5%) pts (167 CR, 7 CRi). 93 (44%) pts were MRD-. 32 (15.1%) pts received HCT on study and 24 (11.4%) pts received it off study. Among MRD- pts (n=93), 46 were randomized to and 45 received blina: 6 (13.3%) pts had 1, 14 (31.1%) had 2, 2 (4.4%) had 3 and 23 (51.1%) had 4 cycles. 3-year OS were 71% and 67% for the blina and the chemo only arm (univariate model: HR 0.75, 95% CI: 0.37-1.50; multivariate model: HR 0.56, 95% CI: 0.25-1.27). 3-year RFS were 69% and 59% for the blina and the chemo only arm (univariate model: HR 0.75, 95% CI: 0.39-1.45; multivariate model: HR 0.67, 95% CI: 0.32-1.42). Among MRD+ pts (n=25), 14 were randomized to and 11 received blina: 7 (63.6%) pts had 2, and 4 (36.4%) had 4 cycles. 3-year OS were 66% and 44% for the blina vs the chemo only arm (univariate model: HR 0.66, 95% CI: 0.12-3.64). 3-year RFS were 64% and 31% for the blina vs the chemo only arm (univariate model: HR 0.64, 95% CI: 0.15-2.74). Frequency of treatment-related toxicities among older pts during different study phases and treatment assignments will be presented. Conclusion Despite evidence of improved outcomes in the whole study cohort, the addition of blina to consolidation chemo for older pts with ALL was not associated with statistically significant improvement of OS or RFS in this exploratory analysis not powered to detect the difference in subgroups. This is possibly due to sample size but may be due to biologic differences in the older adult population. Further studies are needed to definitively determine tolerance and benefit of blina addition to consolidation for older pts with ALL.

Introduction: Based on a donor versus no-donor analysis, UKALLXII/E2993 showed a survival benefit for adults with acute lymphoblastic leukemia (ALL) who underwent allogeneic hematopoietic cell transplantation (alloHCT) in first complete remission (CR1) compared to consolidation/maintenance chemotherapy alone. The follow-up phase 3 E1910 trial (NCT02003222) randomized BCR::ABL1-negative B-lineage ALL patients (pts) aged 30-70 years in measurable residual disease (MRD)-negative CR1 after intensification to conventional chemotherapy (CC) +/- blinatumomab (blin) and demonstrated significantly improved overall survival (OS) with blin (Litzow, NEJM 2024). The current exploratory subgroup analysis evaluates outcomes of MRD-negative pts randomized on E1910 who underwent alloHCT on trial. Methods: Among pts enrolled on E1910, pts in MRD-negative CR1 by 6-color flow cytometry after intensification who were randomized to CC +/- blin and subsequently underwent alloHCT were identified. We compared baseline characteristics, MRD status post induction, relapse-free survival (RFS) and OS using the Kaplan-Meier method and the two-sided log-rank test and Cox model. A multivariable analysis was performed with alloHCT included as a time-varying covariate as well as a landmark analysis comparing the outcome of pts with unfavorable risk on the CC + blin arm who underwent alloHCT versus those who did not. Results: Of 224 MRD-negative randomized pts, 44 underwent alloHCT on trial: 22 in each arm. The median time from randomization to transplant was 3.2 months (mos). The median follow-up from initial registration was 57.8 mos. Baseline demographics including age (median 55 years), gender (53% male), race (89% white) and ethnicity (89% non-Hispanic/Latino) were equally distributed. Compared to CC + blin, the median peripheral blood white cell (WBC) count and blast percentage at diagnosis were higher in the CC arm at 6,640 vs 3,740/uL and 55 vs 9%, respectively, while median marrow blast percentage and overall unfavorable risk as defined in E1910 (55% vs 64%) were similar. Of the 44 MRD-negative pts who proceeded to alloHCT on study, 77% in the CC arm and 64% in the CC+ blin arm were MRD-negative after induction. Myeloablative conditioning was given to the majority of pts (68% CC arm and 73% CC+blin arm) and the most common graft versus host disease prophylaxis was tacrolimus-based on both arms. Among the 44 pts who underwent alloHCT, the observed hazard ratio (HR) comparing relative risk of death between pts randomized to CC+blin or CC only was 0.59 (95% CI: 0.12-2.11) with a 3-year OS rate of 82% versus 71% and the HR comparing relative risk of relapse/death was 0.52 (CI: 0.15-1.79) with a 3-year RFS rate of 82% versus 67%. For patients with unfavorable risk, 3-year OS and 3-year RFS in each treatment arm were both 71% versus 65%. Among 50 pts with unfavorable risk in MRD-negative CR after intensification who were randomized to CC + blin, a landmark analysis performed at 5 mos post randomization showed 3-year OS and RFS rates of 71% versus 90% and 71% versus 86% between the 14 pts who underwent alloHCT and those who did not, respectively. Receipt of alloHCT was a time-varying covariate in a multivariable analysis with gender, WBC count, platelets, hemoglobin, peripheral blood blasts, bone marrow blasts, performance status, and combined molecular risk category. Age, CD20 status, rituximab use, and intention to receive alloHCT were used as stratification factors. In the entire cohort of MRD-negative pts who were randomized, there was a significant association between improved OS and the receipt of CC+blin vs CC alone (HR 0.46, 95% CI: 0.26 - 0.82; p=0.009), better performance status of 0-1 vs ≥2 and favorable vs unfavorable risk ALL. In contrast, the receipt of alloHCT had no significant effect on OS (HR 1.00, 95% CI: 0.49 - 2.01). Conclusions: Within the constraints of small numbers, this exploratory subgroup analysis demonstrates that in pts with newly diagnosed BCR::ABL1-negative B-ALL treated on E1910 who achieved MRD-negativity after intensification, alloHCT outcomes did not appear to be different with or without blin in consolidation. In a multivariate analysis of all MRD-negative pts, receipt of blin but not alloHCT was associated with improved OS. Further investigation is warranted to characterize the relative benefit of blinatumomab in pts receiving alloHCT in frontline consolidation.

Background: The addition of midostaurin (M), an oral multi-kinase inhibitor, to intensive chemotherapy (IC) prolongs survival in newly diagnosed (ND) FLT3 mutated (m) AML. It is not known if there is a benefit to more potent and selective FLT3 inhibitors. Among these is Gilteritinib (G), now approved as a single agent in relapsed/refractory FLT3m AML. Combined with IC, G also leads to high measurable residual disease (MRD)negative (-) composite complete remission (CRc) in FLT3 Internal Tandem Duplication (ITD)m AML. The aim of the PrECOG 0905 study was to compare FLT3m clearance and CRc rates of G vs M with IC in adults with ND FLT3m AML. Methods: We conducted a randomized, open-label, phase 2 trial comparing G to M in combination with IC during induction and consolidation in ND AML pts with centrally PCR detected FLT3 ITD or TKD mutations. Pts age 18-70 with non M3 AML and no known core binding factor rearrangement were eligible. Pts were stratified by mutation type (TKD only vs. ITD (+/- TKD)), NPM1 mutation status, and FLT3-ITD allelic ratio. Induction consisted of cytarabine 100 mg/m2 by continuous infusion daily, on day (d) 1-7 and daunorubicin 90 mg/m2 IV on d 1-3. G 120 mg daily or M 50 mg twice daily was given orally on d8-21. Consolidation (up to 4 cycles) began within 60 d of induction with Cytarabine (1.5-3 g/m2 IV) X 6 doses and G or M (as per randomization) on d8-21. Pts could proceed to transplant (HCT) at any time. Maintenance was not included. The primary outcome was FLT3m MRD (-) CRc after induction. MRD for TKD mutations was tested by PCR (sensitivity 10-2); ITD MRD was tested by amplicon-based NGS (sensitivity 10-4). Safety and efficacy were analyzed in all eligible pts who received treatment. Secondary endpoints included comparison of CRc, MRD by flow cytometry (sensitivity 10-3), and survival. Results: From 11/2019 to 11/2022, 722 pts were screened at 37 centers, 180 pts randomized, and 177 pts (58% female, 77% white, 8.5% black, 8.5% hispanic) treated on the G (n=90) or M (n=87) arm. Median age was 54, with 27.7% > age 60. FLT3-ITD was present in 80% in the G arm and 78.2% in the M arm. Of those with FLT3-ITD, NPM1 was detected in 56.9% pts in G arm and 58.8% in M arm. 24.4% G and 20.7% M pts had co-occuring FLT3-ITD, NPM1 and DNMT3A mutations. Adverse karyotype was seen in 3.4% G and 9.3% M while 10% G and 13.8% M were ELN 2022 adverse risk. For pts on G arm, 85.6% achieved CRc compared to 72.4% for M (p=0.042). 5 (5.6%) pts on G arm and 6 (6.9%) on M arm received 2 cycles in induction. Post induction, the FLT3m- CRc rate was 40% for G vs 47.1% for M (p=0.366). FLT3-TKD only mutated pts achieved CRc in 88.9 % with G and 63.2% with M and FLT3m- CRc in 72.2% and 63.2% respectively. FLT3-ITDm (+/- TKDm) pts achieved CRc/FLT3m- CRc in 84.7%/31.9% with G and 75%/42.6% with M, respectively. In pts with FLT3-ITD, NPM1 and DNMT3A mutations, 95.5% G and 72.2% M achieved CRc and 50% G vs 33.3% on M achieved FLT3m- CRc. Flow cytometry MRD negative CRc was documented in 64.4% on G arm and 59.8% on M arm after induction (p=0.539). On G arm 67 (74%) patients received at least one cycle of consolidation compared to 53 (61%) pts on M arm. On exploratory analysis, 54 (66%) G and 40 (46%) M were reported to proceed to HCT in first remission. FLT3m testing was done post consolidation cycle 1 in 27 pts in FLT3m+ CRc after induction and 15/18 (83%) on G and 4/9 (44.4%) on M converted to FLT3m-. On multivariate logistic regression analysis for FLT3m-CRc post-induction, FLT3-ITD allelic ratio, NPM1m, WBC and hemoglobin at baseline were significant at the 0.10 two-sided level, while treatment arm, and 2017 ELN risk were not. There were no deaths from treatment-related (TR) adverse events (TRAEs) while grade >=3 TRAE was reported in 73%G vs 70% M during induction and 79%G vs 73%M pts during consolidation. Conclusion: Induction therapy with daunorubicin 90 mg/m2 X 3 days, cytarabine 100 mg/m2 and gilteritinib results in an excellent CRc rate with no TR deaths in pts with ND FLT3m AML up to age 70. Compared to M, G increased the CRc but not the FLT3m- CRc rate after induction. More post induction FLT3m+CRc pts who received G became FLT3m- after consolidation cycle 1 and more G pts succeeded in proceeding to HCT. Future survival data will help evaluate the clinical impact of G and MRD assessments in ND FLT3mAML. Larger studies will be needed to establish most predictive timing of MRD and for definitive comparisons of these drugs in patients with specific mutation profiles ( ie TKD, ITD/NPM1/DNMT3).

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 (<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 >=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 <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.

Background: Menin, a protein involved in transcriptional regulation, plays a role in the genesis of multiple cancers. Preclinical data from BMF-219, an investigational, highly selective, oral small-molecule inhibitor of menin, show sustained potent abrogation of menin-dependent oncogenic signaling. BMF-219 is the first and only covalent menin inhibitor in clinical development and is being evaluated in multiple hematologic malignancies, solid tumors, and diabetes mellitus. COVALENT-101 (NCT05153330) is a Phase I dose-escalation and -expansion study of BMF-219 in R/R AL (Cohort 1), DLBCL (Cohort 2), MM (Cohort 3), and CLL (Cohort 4). Here we report preliminary safety, PK and anticancer activity data from Cohort 1 (AL). Methods: Doses of BMF-219 are escalated independently for each indication, initially in single-subject cohorts followed by a “3 + 3” design. Eligible patients (pts) include adults with R/R AL ineligible for standard therapy. Initially pts were enrolled agnostic to molecular status. A subsequent amendment introduced quotas for KMT2Ar (MLL1r), NPM1 and other known menin-dependent mutations: CEBP/A, MLL1-PTD, MN1, NUP98, NUP214, PICALM-AF10, SETBP1. Prior exposure to reversible menin inhibitor therapy is permitted. Subjects receive BMF-219 daily for continuous 28-day cycles until progression/intolerability. There are 2 parallel dose-escalation arms: pts not taking (Arm A) or taking (Arm B) moderate or strong CYP3A4 inhibitors. The study is ongoing and accruing in the escalation. Expansion cohorts will enroll pts to obtain further safety and efficacy data at the OBD/RP2D. Results: As of data cutoff of 7/24/2023, 26 pts with R/R AL (24 AML; 2 ALL) are enrolled; 7 remain on study treatment. Baseline characteristics include 17(65%) males and 9(35%) females with a median age of 57.5 years (range 33-84). There is a median of 4 (range 1-8) prior lines of therapy and 11 (42%) with prior HSCT(s). Six pts (23%) had KMT2Ar, 3 (12%) KMT2A-PTD, 4 (15%) NPM1, and 13 (50%) WT for KMT2A and NPM1. Dosing began with single-patient cohorts at 100 mg QD (Arm A) and 25 mg QD (Arm B) and has been escalated through 4 dose levels. Thus far, pts have been dosed up to 500 mg QD (Arm A) and 125 mg QD (Arm B). BMF-219 exposures were comparable between arms, with ~2-4-fold higher exposures observed with co-administration of a moderate or strong CYP3A4 inhibitor. At the highest dose (DL4) in which PK was evaluated, Arm A (500 mg QD) and Arm B (125 mg QD), pts on average achieved ~50% of target exposure (2000 ng*hr/mL) with some pts surpassing it. Higher QD dosing or corresponding BID dosing is expected to achieve desired exposure. BMF-219 has generally been well tolerated with no DLTs observed and no discontinuations due to treatment-related toxicities. No related QTc prolongation was observed. At the time of data cutoff, 23 of 26 pts were included in the safety population. Common TRAEs (≥10%) include vomiting 13% (3) and Differentiation Syndrome (DS) 13% (3). No Grade 5 TRAEs were reported. The only common Grade ≥3 TRAE (≥5%) was DS 13% (3). The efficacy evaluable population includes AML pts who meet the following criteria: dosed at or near predicted efficacious dose (500 mg or above [Arm A]; 125 mg or above [Arm B]), had known menin-dependent mutations, and completed at least one scheduled response assessment (or had a minimum of 7 doses if discontinued prematurely). Thus far, 2 of 5 efficacy evaluable patients achieved a complete remission (1 CR; 1 CRi) and both continue BMF-219 treatment. Patient A: 39/M, NUP98-NSD1, ECOG=0, 500 mg QD, Arm A, 4 prior lines of treatment including intensive chemotherapy and allo-HSCT. At C1D27, marrow blasts were reduced to 6% from 13% at study entry. The patient achieved CR at C2D28 with 0% blasts.Patient B: 70/F, NPM1m, ECOG=1, 125 mg QD, Arm B, 1 prior line of treatment with decitabine and an investigational agent. At C1D28, marrow blasts were reduced to 34% from 52% at study entry. The patient achieved CRi with 3% blasts at C2D28. Conclusion: BMF-219 is generally well tolerated with no DLT observed (and able to be taken with and without CYP3A4 inhibitors) with no pts discontinuing therapy due to toxicity. BMF-219 dose escalation is ongoing and approaching target exposure. BMF-219 demonstrates early signs of clinical activity in different genomic subgroups. The trial is ongoing and includes enrollment for pts diagnosed with AL, DLBCL, MM and CLL.