Citations

Abstract Background: MyeloMATCH is an NCI-sponsored initiative for acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) employing a Master Screening and Reassessment Protocol (MSRP) to assign patients (pts) to a pt and disease biology-specific clinical trial. Several trials evaluating initial therapies are currently open, while subsequent trials dedicated to eradicating measurable residual disease during consolidation and including stem cell transplant are being developed. A pt enrolled at diagnosis may be followed longitudinally and be eligible for trials in sequential tiers throughout the treatment course. We report key data concerning the first cohort of pts enrolled on the MSRP. Methods: After pts with suspected AML or MDS consent for the MSRP, blood and marrow are sent to the myeloMATCH Molecular Diagnostics Network (MDNet) of central CLIA labs operating under a single Investigational Device Exemption to rapidly define molecular, cytogenetic, and immunophenotypic characteristics. These data are catalogued by a bioinformatics team (MATCHBox) and reviewed daily to assign participants to an available trial based on pt and disease features. A Tier Advancement Pathway (TAP) allows standard of care therapy with potential for assignment to subsequent myeloMATCH trials. Since activation in May 2024, 550 patients age≥18 were enrolled on the MSRP from 76 institutions: 48 Academic, 14 NCORP, 11 community, 3 VA. There are currently 4 open randomized AML trials (≥age 60 or unfit with mutant FLT3, ≥age 60 IDH2 mutant AML, fit age<60 ELN 2017 intermediate-risk AML, fit age<60 ELN 2017 adverse risk) and 1 MDS trial(IDH2 mutant). Patients not eligible for an open protocol were assigned to TAP. Results: Of the 550 pts consented, 491 completed screening assays; 49 had no or incomplete samples; 10 withdrew before completed analysis. Median cytogenetic turnaround time (TAT) was 69 hours (91% within 72 hours), and median Next Generation Sequencing (NGS) TAT from receipt was 49 hours (95% within 72 hours). Seventy-six pts (of 491 with assay data) were not assigned due to non-AML or non-MDS diagnoses, the most common being: B-ALL [n=11], MPN [9], benign marrow [9], APML [7], and MPAL [6]. The AML/MDS verified cohort was 415 pts, 366 (89.2%) patients with AML (45% age <60) and 49 (11.8%) with MDS. The median age at screening was 63 years (range:18-95) and 186 (45%) were female. Eighty-two percent identified as White, 7.5% Black, 3% Asian, 7% unknown, and 9% as Hispanic. The most frequent mutations in the AML pts were NPM1 (24.0%), DNMT3A (22.7%), TET2 (19.9%), NRAS (18.0%), FLT3 (18.0% ITD, TKD 7.1%), TP53 (14.5%), and CEBPA (8.7%); IDH1/2 mutation rates were 8.2% and 13.7%, respectively. Co-mutations include FLT3/NPM1 (9.8%), NPM1/IDH2 (4.4%), IDH1/2 and any RAS (3.8%). Karyotypes were normal in 40.4%, complex 20.8%, inv(16) 6.0%, MLL/KMT2A 4.6% and t(8;21) 1.9%. 29% had favorable risk disease, 29% intermediate, and 42% adverse (ELN 2017). In MDS, mutations included: TP53 (36.7%), RUNX1 (20.4%) ASXL1 (20.4%), TET2 (18.4%), spliceosome mutations (SRSF2, SF3B1, U2AF1 and ZRSR2, 28.6%) andIDH1/2 in 4.1% and 6.1%, respectively. Karyotypes were normal in 24.5%; complex in 40.8%. By IPSS-R, 2.4% were low, 73.8% intermediate, 2.4% high, and 21.4% very high risk. 82/415 (20%) pts were assigned to initial therapy protocol, with an increase in assignment rate to 44% in the most recent two months. 71/415 pts (16%) were enrolled in one of the MyeloMATCH studies. Three-hundred forty-four pts (80%) were assigned and enrolled to TAP (296 AML, 48 MDS) for potential assignment to subsequent tier trials. In the TAP AML pts, 99 (33%) have completed initial treatment, including intensive chemotherapy (IC) in 62% of pts and hypomethylating agents/venetoclax (HMA/VEN) in 38%. In pts <60 years of age, 87% received IC v. 13% with HMA/VEN, in >60 34% IC v. 66% HMA/VEN and in age 60-75 42% IC v. 58% HMA/Ven. Conclusion: MyeloMATCH has screened over 500 pts from academic and community sites in the US and Canada in 14 months, meeting the TAT goal of sample acquisition to results of <72 hours. Assignment to treatment protocols has substantially increased recently. As additional trials open (12 in development) we expect the percentage of pts enrolled on MSRP who go on to therapeutic trials will markedly increase, thereby allowing a personalized medicine approach for a broad group of US and Canadian adult pts with AML and MDS.

Abstract The current European Leukemia Net guidelines (ELN22) classify AML patients with intermediate-risk cytogenetics and MDS-associated mutations (MDSm, mutations in ASXL1, BCOR, EZH2, RUNX1, SF3B1, SRSF2, STAG2, U2AF1, ZRSR2) as adverse-risk but do not use MDSm+ to alter the risk stratification of patients who otherwise classify as favorable-risk. NPM1 mutations (NPM1+) are one of the most common alterations in AML and remain a favorable-risk biomarker for patients without co-occurring FLT3-ITD mutations or adverse-risk cytogenetics (NPM1+/ITD-/ARcyto-). However, prior studies have shown that older patients (≥65 years) with favorable-risk AML, including NPM1+/ITD-/ARcyto- genotype, have significantly higher relapse rates and decreased survival despite receiving comparable intensive chemotherapy regimens to their younger counterparts. Given that MDSm frequency increases with age in patients with NPM1+ AML, it raises the question as to whether MDSm contribute to poorer outcomes in older patients. To date, there have been differing results in retrospective studies examining the effect of MDSm on NPM1+ AML. Some cohorts demonstrate worse outcomes in those that have NPM1+/MDSm+ AML (Chan et al., Blood Adv. 2024), whereas others do not show a significant difference in NPM1+ AML with or without MDSm (Eckardt et al., Leukemia 2023; Othman et al., Blood 2024; Ruhnke et al., Blood Adv. 2025). We examined the mutational landscape in a large group of pre-treatment, diagnostic specimens from 271 patients, which included 119 patients enrolled in SWOG clinical trials (SWOG-9031, SWOG-9333, S0106, and S0112), 96 patients from the UW/FHCC Hematopoietic Repository, and 56 patients from the BeatAML cohort. All patients were treated with curative intent as per standard practice or on clinical trials and had adequate cytogenetic information and long-term follow-up data. Event-free and overall survival (EFS, OS) were estimated using the Kaplan-Meier method and compared using Cox regression models stratified by cohort. MDSm+ occurred in 17% of patients, with the most common mutations being in SRSF2 (7%) and SF3B1 (3%). To assess the impact of MDSm on outcomes of favorable-risk NPM1+ AML, we performed univariate analyses comparing OS and EFS for NPM1+ AML grouped by ELN22 favorable risk/MDSm-, ELN22 favorable/MDSm+, and ELN22 intermediate/adverse risk. Compared to NPM1+/MDSm- (n=116), favorable-risk NPM1+/MDSm+ (n=33) had worse OS with HR 2.0 [95% CI (1.1, 3.3), p=0.008] and had similar OS to those that are classified as ELN22 intermediate/adverse risk (n=122). There was no significant difference in EFS or complete remission rates between NPM1+ favorable risk with and without MDSm (p=0.36 and p=0.6, respectively). When we grouped the ELN22 favorable risk patients by age (<65 years vs. 65+ years), MDSm+ in younger patients did not show a difference for OS (HR 0.99, p=0.98). Older ELN22 favorable-risk patients (≥65) had poor OS regardless of presence of MDSm compared to younger MDSm- patients: older MDSm- (n=91) with HR 2.4, 95% CI (1.3, 4.6), p=0.005 and older MDSm+ (n=25) with HR 3.5, 95% CI (1.9, 6.3), p<0.0001. There was a trend toward worse OS in MDSm+ compared to MDSm- older patients, but this was not statistically significant (HR 1.42, p=0.33). Since most MDSm are in splicing factor genes (SF3B1, SRSF2, U2AF1, ZRSR2), we examined the effect of splicing factor mutations vs. other MDSm+ in ELN22 favorable risk and did not find a significant difference in OS (HR=1.01, p=0.97). Those with non-splicing MDSm+ had worse EFS compared to MDSm- and splicing MDSm+ (HR 4.12, p=0.0037), although no difference in OS. In this study, MDSm+ in the context of favorable-risk NPM1+ AML are associated with worse OS in a univariate analysis. However, this difference is likely due to the increased prevalence of MDSm with increasing age and overall worse outcomes of NPM1+ AML in older patients. When stratified by age, older NPM1+ AML patients had worse OS than younger NPM1+ patients overall, although presence of MDSm trended toward even worse OS in older patients. In younger patients, MDSm+ are not associated with a significant difference in OS, which is a similar finding compared to prior studies. Our findings suggest that NPM1+ AML is not necessarily “favorable-risk” in older patients, particularly with concurrent MDSm. Therefore, further understanding of the underlying biology of age in the context of NPM1+ AML is needed to improve outcomes for older patients.

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.

NPM1 mutations (NPM1+) are found in about 30% of adult AML. While NPM1+ are generally associated with favorable risk, prior studies have shown that NPM1+ older patients, defined as ≥ 65 years, have significantly worse outcomes. The updated European Leukemia Net 2022 (ELN22) now classifies NPM1+ AML patients with FLT3-ITD (ITD+) and MDS-associated mutations (MDSm+) as adverse-risk, while NPM1+/ITD-/MDSm+ patients remain favorable-risk unless they have an adverse-risk karyotype. A recent report (Chan et al., Blood Adv 2024) found MDSm+ conferred worse OS only in patients ≥ 60 years; however another report (Othman et al., Blood 2024) did not find MDSm+ were significantly associated with adverse outcomes in a larger cohort of NPM1+ patients. To further assess this question, we examined the mutational landscape in a large cohort of pre-treatment, diagnostic specimens from 456 patients enrolled in SWOG clinical trials (SWOG-9031, SWOG-9333, S0106, and S0112) and 126 patients from the UW/FHCC Hematopoietic Repository (Total N=582). Patients were treated with curative intent as per standard practice or clinical trials. Out of the 582 patients, 191 were NPM1+ (33%), of which 148 patients had cytogenetic and long-term outcome data. Kaplan-Meier and cumulative incidence estimates were estimated. C-statistics and AUC for Cox, cause-specific and logistic regression models for overall survival (OS), event-free survival (EFS), time to relapse (TTR, calculated in n=106 who achieved complete remission [CR], death in remission analyzed as a competing risk) and CR were calculated for age, ELN17, and ELN22, as well as ELN17 and ELN22 adjusting for age. ELN17 favorable-risk patients reclassified as adverse-risk (N=5 of 108) demonstrated significantly shorter EFS (HR=2.50, p=0.05) and CR rate (OR=0.20, p=0.024), although with similar OS (HR 1.30, p=0.66) and TTR (HR=1.20, p=0.86). ELN17 favorable-risk patients reclassified as ELN22 intermediate-risk (N=23 of 108) did not show a significant difference in OS (HR 1.47, p=0.20), EFS (HR 1.35, p=0.12), CR rate (OR 0.75, p=0.46), or TTR (HR=1.64, p=0.11) compared to ELN22 favorable-risk. For ELN17 intermediate-risk (N=40), 5 patients were reclassified as ELN22 adverse-risk (12.5%) and had significantly shorter EFS (HR 2.89, p=0.037) compared to ELN22 intermediate risk, although there was not a significant difference in CR rate (OR 0.31, p=0.23) or OS (HR 0.81, p=0.67). We next compared the prognostic significance of age relative to ELN risk classification. Age was associated with higher C-statistics (OS=0.65, TTR=0.57 and EFS=0.60) and AUC (CR=0.64) compared to both ELN17 (OS=0.56, TTR=0.54, EFS=0.54, CR=0.54) or ELN22 (OS=0.57, TTR=0.57, EFS=0.57, CR=0.58). The combination of age and ELN22 resulted in the highest C-statistics for OS, TTR, and EFS (OS=0.68, TTR=0.60, EFS=0.64). To further assess the impact of MDSm on risk-stratification of NPM1+ AML, we performed multivariable analyses adjusting for FLT3-ITD, MDSm, and age in patients without adverse-risk disease. These analyses showed MDSm did not have a significant association with OS when controlling for age or FLT3-ITD. We also compared ELN22 favorable-risk patients with and without MDSm (MDSm+ N=18; MDSm- N=61). Compared with the MDSm-, there was a trend toward an inferior OS (HR 1.85, p=0.054) for MDSm+ patients but not EFS (HR 1.38, p=0.3) or TTR (HR 1.2, p=0.64). When stratified by age (<65, N=53 vs. ≥65, N=26), MDSm+ in younger patients did not show a difference for OS (HR 0.96, p=0.96), EFS (HR 0.63, p=0.53) or TTR (HR 0.4, p=0.37). Older ELN22 favorable-risk patients (≥65) had similarly poor OS (MDSm- HR 3.33 and MDSm+ 3.27, respectively, p=0.001 for both) and EFS (MDSm- HR 3.11 and MDSm+ 2.39, p=0.001 and 0.01) compared to younger MDSm- patients. In our study, the ELN22 guidelines incrementally improve risk stratification for EFS in NPM1+ patients. However, age remains the most prognostic factor, and patients ≥ 65 years have similar adverse clinical outcomes, whether classified as favorable risk by ELN17, ELN22, or incorporating MDSm. Moreover, MDSm do not confer a worse prognosis in NPM1+ patients when accounting for age or FLT3-ITD status. These findings differ from a recent report by Chan et al. and are in keeping with the report by Othman et al. Therefore, further understanding of the underlying biology of age and its effect on NPM1+ AML is needed to improve outcomes for older patients.

AbstractIntroductionAcute myeloid leukemia (AML) remains one of the deadliest hematopoietic malignancies. A better understanding of the molecular biology governing AML may lead to improved risk stratification and facilitate the development of novel therapies. Proteins are responsible for much of the biology of cells. Several studies have examined the global proteome in bulk mononuclear cells (MNCs) from AML specimens, which are comprised a heterogenous population of cells at various stages of differentiation.MethodsGiven the potential impact of the nonleukemic cells on protein expression profiles, we applied an integrative proteogenomic approach utilizing next‐generation sequencing and mass spectrometry‐based proteomics to identify novel protein biomarkers in unsorted MNCs and viable leukemic blasts (VLBs) isolated from blood and bone marrow specimens obtained at the time of AML diagnosis.ResultsWe identified significant differences in protein expression between VLBs and MNCs. Subsequent studies (N = 27) focused on proteomic profiling of VLBs that identified novel candidate biomarkers associated with mutational genotypes and clinical outcome, some of which were recapitulated in an independent cohort of patients. Using mass spectrometry, we also detected mutated protein products, some of which were predicted via in silico analyses to be potential neoantigens amenable to adoptive immunotherapy. As previously described, analyses comparing transcript and protein expression showed an overall modest correlation between mRNA and protein dataset, but enriching for genes associated with mutations significantly improved the protein–RNA correlation.ConclusionTogether, the results provide insight into the biology of VLBs and demonstrate the gains derived from examining the proteome in addition to genome and transcriptome.

TPS4201 Background: Poorly differentiated, extrapulmonary NEC are rare cancers with median overall survival (OS) <1 year. Treatment is extrapolated from small cell lung cancer (SCLC) with use of P (cisplatin or carboplatin) + E. More effective treatment regimens and predictive biomarkers are needed to improve outcomes. In SCLC, induction therapy with combination of P/E + PD-L1 checkpoint inhibitor atezolizumab and maintenance atezolizumab improved OS (12.3 months vs 10.3 months; HR 0.70, 95% CI 0.54 – 0.91, P=0.007) vs P/E alone (1). No study to date has compared PD-1/PD-L1 inhibition during induction only vs during induction and maintenance therapy. In SCLC, distinct molecular subtypes can be identified by the presence of specific transcription factors (e.g., ASCL1, NEUROD1, POU2F3) or an inflamed gene signature (SCLC-I), with SCLC-I pts more likely to benefit clinically from the addition of immunotherapy (2). In this study we plan to test the benefit of adding atezolizumab to induction P/E as well as the role of adding maintenance atezolizumab after induction P/E plus atezolizumab. We also plan to correlate tumor- and blood-based subtype biomarkers with response to therapy. Methods: Eligible pts ≥18 years old have evaluable, histologically confirmed extrapulmonary NEC, Zubrod PS ≤2, and are allowed to have up to 1 cycle of P/E prior to enrollment. P (cisplatin 75 mg/m2 or carboplatin AUC 5, iv) on day 1, E 100 mg/m2 iv on days 1-3, and atezolizumab 1200 mg iv on day 1 of q21 day cycles. Pts are randomized to 1 of 3 arms: A) Induction P/E + atezolizumab -> maintenance atezolizumab B) Induction P/E + atezolizumab -> observation C) Induction P/E -> observation. The primary objective is to compare the overall survival (OS, from randomization) between arms in a fixed sequence: A vs C -> B vs C -> A vs B. Secondary objectives include comparing OS (from start of maintenance/observation), progression free survival, response rate, duration of response, and safety/tolerability across arms. Tumor and blood samples will be banked for future biomarker analyses, including immunohistochemistry of transcription factors on tissue and whole exome sequencing on tumor and circulating tumor DNA. With 189 pts (168 eligible), the study has 84% power to detect an improvement in 12-months OS from 35% to 57.5% (HR 0.53). This study was activated December 2021 with 3 pts enrolled over 1 year due to restricting enrollment of NEC of small cell histology only. The protocol was amended in January 2023 to broaden eligibility to all NEC subtypes (small cell, large cell, and undefined histology with Ki-67 ≥55%). As of January 2024, 35 patients have been enrolled. A protocol amendment is planned to remove the need for Ki-67 index for NEC of genitourinary origin to improve accrual. 1. Horn L, et al. N Engl J Med 2018. 2. Gay CM, et al. Cancer Cell 2021. Clinical trial information: NCT05058651 .

Tyrosine kinase inhibitors (TKIs) have improved the outcomes of patients with Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL). Many older patients (pts) are not good candidates for intensive chemotherapy and are treated with TKIs plus corticosteroids or low-intensity chemotherapy. Although the remission rates with this approach have been high, the median disease-free survival (DFS) has been short. Therefore, novel treatment strategies are needed. This trial evaluated the feasibility of combining the TKI dasatinib with prednisone and blinatumomab in older pts with Ph+ ALL. Here we present updated results (median follow-up, 4.3 years). Methods: This trial was activated through the NCTN in January 2015 and closed to accrual in April 2021. Pt eligibility included: age ≥ 65 years; Ph+ or Ph-like ALL (with dasatinib-sensitive fusions or mutations); newly diagnosed or relapsed/ refractory; no evidence of central nervous system (CNS) disease; and adequate organ function. Treatment: For induction, pts received dasatinib 140 mg/d orally (PO) Days 1-56 along with prednisone 60 mg/m 2/d PO Days 1-24. Pts achieving complete remission (CR) or CR with incomplete count recovery (CRi) (Day 28 or Day 56) continued dasatinib until Day 84, followed by 3 cycles of post-remission therapy (PRT) with blinatumomab/ dasatinib. Pts not achieving CR or CRi by Day 56 received re-induction with blinatumomab. The response rate was assessed on Day 35 of blinatumomab. Pts not achieving CR/ CRi could receive a second cycle of blinatumomab. This was followed by 3 cycles of PRT with blinatumomab/ dasatinib. Maintenance therapy consisted of prednisone 60 mg/m 2/d x 5 days every 28 days for a total of 18 cycles, along with dasatinib 140 mg po qd indefinitely. CNS prophylaxis included intrathecal (IT) methotrexate every 4-6 weeks x 8 doses. IT methotrexate was given at least 2 days apart from blinatumomab. Response was assessed at Days 28, 56, and 84, and additional time points were dependent on response. Minimal residual disease (MRD) was assessed centrally by multi-color flow cytometry on Day 28. Statistics: A total of 24 eligible patients were accrued. The primary objective was the feasibility of the combination therapy. The combination was to be deemed feasible if the dose-limiting toxicity (DLT) was &lt; 33%. DLT included: &gt; Grade 3 non-hematologic toxicities (excluding nausea, vomiting, diarrhea) and Grade 4 neutropenia lasting &gt; 42 days. The primary results were reported in 2022 with a median of 2.7 years of follow-up. Herein, we report long-term outcomes for these patients. Results: The median age was 73 years (range 65-87). All pts had newly diagnosed Ph+ ALL; 79% of Ph+ pts had additional cytogenetic abnormalities. During induction, 2 pts experienced treatment-related non-hematologic Grade 4 toxicities. No Grade 4 or higher treatment-related non-hematologic toxicities occurred during post-remission therapy or maintenance. The toxicity of the combination was deemed acceptable. Twenty-two of 24 pts (92%) achieved a CR during dasatinib and prednisone induction therapy. Four did not receive PRT (2 due to adverse events, 1 to receive a transplant, and 1 because of insurance issues). Sixteen pts who achieved CR had MRD data. Six of 16 pts (38%) were MRD undetectable by multi-color flow cytometry on Day 28. Most sites also monitored patients' 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 time point after treatment, with at least 12 of these patients achieving complete molecular remission. Four patients remain on maintenance. The median follow- up for pts who are alive is 4.3 years (range 2.6-6.5 years). The median overall survival (OS) is 6.5 years (95% CI 3-NA) and the median DFS has not been reached as of June 29, 2023. Kaplan-Meier 3-year estimates of OS and DFS are 75% (95% CI 52%-88%) and 72% (95% CI 49%-87%), respectively (Figure). Of the 8 relapses, 4 patients were CD19+ and 3 had T315I mutations. Conclusions: Median DFS and OS with dasatinib and blinatumomab in this older group of Ph+ ALL patients remain excellent despite only 1 patient proceeding to an allogeneic transplant. Further correlative studies (single cell transcriptomics and DNA methylation sequencing) are being planned to evaluate predictors of relapse and will be presented at the meeting.

Abstract Novel treatment strategies are needed for the treatment of Philadelphia chromosome–positive (Ph+) acute lymphoblastic leukemia (ALL) in older patients. This trial evaluated the feasibility and outcomes with the anti-CD19 bispecific T-cell–engaging antibody, blinatumomab, in combination with dasatinib and steroids. Patients 65 years of age or older with Ph+ or Ph-like ALL (with dasatinib-sensitive fusions/mutations) were eligible and could be newly diagnosed or relapsed/refractory. Induction therapy consisted of dasatinib/prednisone. Patients not achieving response by day 56 proceeded to blinatumomab reinduction therapy. Patients achieving response with induction or reinduction therapy proceeded to blinatumomab/dasatinib postremission therapy for 3 cycles followed by dasatinib/prednisone maintenance. All patients received central nervous system prophylaxis with intrathecal methotrexate for a total of 8 doses. Response was assessed at days 28, 56, and 84 and at additional time points based on response parameters. Measurable residual disease was assessed centrally by 8-color flow cytometry at day 28. A total of 24 eligible patients with newly diagnosed Ph+ ALL were enrolled with a median age of 73 years (range, 65-87 years). This combination was safe and feasible. With a median of 2.7 years of follow-up, 3-year overall survival and disease-free survival were 87% (95% confidence interval [CI], 64-96) and 77% (95% CI, 54-90), respectively. Although longer follow-up is needed, these results are encouraging, and future trials are building on this backbone regimen. This trial was registered at www.clinicaltrials.gov as #NCT02143414.

PURPOSE Chemotherapy outcomes in older patients with Philadelphia (Ph) chromosome–negative B-acute lymphoblastic leukemia (ALL) are very poor. Here, we evaluated blinatumomab as induction and consolidation therapy followed by prednisone, vincristine, 6-mercaptopurine, and methotrexate (POMP) maintenance chemotherapy in this patient population. PATIENTS AND METHODS Patients were treated at National Clinical Trial Network sites. Eligibility criteria included age ≥ 65 years and newly diagnosed Ph chromosome–negative B-ALL. Patients received blinatumomab as induction for one-two cycles until attainment of response (complete remission (CR) and CR with incomplete count recovery). Patients then received three cycles of consolidation with blinatumomab followed by 18 months of POMP maintenance chemotherapy. Eight doses of intrathecal methotrexate were administered as central nervous system prophylaxis. RESULTS Twenty-nine eligible patients were enrolled. The median age was 75 years, and the median bone marrow blast count at diagnosis was 87%. Cytogenetic risk was poor in 10 patients (34%), and five of 14 patients (36%) tested had the Ph-like ALL gene signature. Nineteen patients (66%; 95% CI, 46 to 82) achieved CR. Kaplan-Meier 3-year disease-free survival and overall survival estimates were 37% (95% CI, 17 to 57) and 37% (95% CI, 20 to 55), respectively. CONCLUSION Blinatumomab was well tolerated and effective in the treatment of older patients with newly diagnosed Ph chromosome–negative B-ALL, including patients with poor-risk cytogenetics. The 3-year disease-free survival and overall survival results are encouraging and suggest that this approach should be further explored.

Abstract Tyrosine kinase inhibitors (TKIs) have improved the outcomes of patients with Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL). Many older patients (pts) are not good candidates for intensive chemotherapy and are treated with TKIs plus corticosteroids or low intensity chemotherapy. Although the remission rates with this approach have been high, the median disease-free survival (DFS) has been short. Therefore, novel treatment strategies are needed. This trial evaluated the feasibility of combining the TKI dasatinib with prednisone and blinatumomab in older pts with Ph+ ALL. Methods: This trial was activated through the NCTN in January 2015 and closed to accrual in April 2021. Pt eligibility included: age ≥ 65 years; Ph+ or Ph-like ALL (with dasatinib-sensitive fusions or mutations); newly diagnosed or relapsed/ refractory; no evidence of central nervous system (CNS) disease; and adequate organ function. Treatment: For induction, pts received dasatinib 140 mg/d orally (PO) Days 1-56 along with prednisone 60 mg/m 2/d PO Days 1-24. Pts achieving complete remission (CR) or CR with incomplete count recovery (CRi) (Day 28 or Day 56) continued dasatinib until Day 84 followed by 3 cycles of post-remission therapy (PRT) with blinatumomab/ dasatinib. Pts not achieving CR or CRi by Day 56 received re-induction with blinatumomab. Response was assessed at Day 35 of blinatumomab. Pts not achieving CR/ CRi could receive a second cycle of blinatumomab. This was followed by 3 cycles of PRT with blinatumomab/ dasatinib. Maintenance therapy consisted of prednisone 60 mg/m 2/d x 5 days every 28 days for a total of 18 cycles along with dasatinib 140 mg po qd indefinitely. CNS prophylaxis included intrathecal (IT) methotrexate every 4-6 weeks x 8 doses. IT methotrexate was given at least 2 days apart from blinatumomab. Response was assessed at Days 28, 56, 84 and additional time points were dependent on response. Minimal residual disease (MRD) was assessed centrally by multi-color flow cytometry at Day 28. Statistics: 9 eligible/ evaluable pts receiving PRT were to be evaluated before enrolling additional pts. Dose-limiting toxicities (DLTs) were defined as: &gt; Grade 3 non-hematologic toxicities with the exception of nausea, vomiting, or diarrhea (if manageable with supportive care measures) or Grade 4 neutropenia lasting &gt; 42 days with possible relationship to dasatinib or blinatumomab. If due to unexpected accrual, 12 pts were evaluable for DLT, the following rules would apply. If &gt; 4 of the 12 pts experienced a DLT, the study would be temporarily closed pending review. Upon re-opening, 8 additional eligible and evaluable pts would be enrolled for a total of 20 pts receiving blinatumomab. Results: Due to rapid accrual, 16 pts enrolled before accrual was paused to assess feasibility and safety. Twelve pts were evaluable for DLT and 4 experienced a DLT: Grade 3 dyspnea and gastrointestinal pain (n=1), Grade 3 hypertension (n=1), Grade 3 dyspnea (n=1), Grade 3 hyperglycemia (n=1). These adverse events were deemed acceptable by the NCI and FDA and the study re-opened. A total of 25 eligible pts were accrued. The median age was 73 years (range 62-87). All pts were newly diagnosed. One pt was Ph-like, with the remainder being Ph+; 89% of Ph+ pts had additional cytogenetic abnormalities. During induction, 2 pts experienced treatment-related non-hematologic Grade 4 toxicities. No Grade 4 or higher treatment-related non-hematologic toxicities occurred during post-remission therapy or maintenance. Twenty-three out of 25 pts (92%) achieved a CR during dasatinib-based and prednisone induction therapy. Four did not receive PRT (2 due to adverse events, 1 to receive transplant, 1 because of insurance issues). Sixteen pts who achieved CR had MRD data. Five out of 16 pts (31%) were MRD negative at Day 28. One pt remains on PRT and 10 are on maintenance. The median follow up for pts who are alive is 1.7 years. The median overall survival (OS) and DFS have not been reached as of July 8, 2021. Kaplan-Meier 3-year estimates of OS and DFS are 85% (95% CI 58%-95%) and 80% (95% CI 55%-92%), respectively (Figure). Conclusions: This trial demonstrates the feasibility of combining dasatinib and blinatumomab in Ph+ ALL. In addition, with 1.7 years of follow up, outcomes are encouraging with high estimated 3-year DFS and OS. Longer follow up will be needed to determine the durability of these results. Figure 1 Figure 1. Disclosures Advani: Kite Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Research Funding; Glycomimetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Immunogen: Research Funding; OBI: Research Funding; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Research Funding; Macrogenics: Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding. Moseley: BioSight Ltd: Consultancy. Wood: Pfizer, Amgen, Seattle Genetics: Honoraria; Juno, Pfizer, Amgen, Seattle Genetics: Other: Laboratory Services Agreement. Park: Intellia: Consultancy; Kura Oncology: Consultancy; BMS: Consultancy; Affyimmune: Consultancy; Curocel: Consultancy; Novartis: Consultancy; Artiva: Consultancy; PrecisionBio: Consultancy; Servier: Consultancy; Kite Pharma: Consultancy; Innate Pharma: Consultancy; Minerva: Consultancy; Autolus: Consultancy; Amgen: Consultancy. Wieduwilt: Gilead: Membership on an entity's Board of Directors or advisory committees; Reata: Current holder of stock options in a privately-held company. Jeyakumar: Jazz: Research Funding; Pfizer: Research Funding. Atallah: Abbvie: Consultancy, Speakers Bureau; BMS: Honoraria, Speakers Bureau; Takeda: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Amgen: Consultancy. Gerds: PharmaEssentia Corporation: Consultancy; CTI BioPharma: Research Funding; Sierra Oncology: Consultancy; AbbVie: Consultancy; Celgene/Bristol Myers Squibb: Consultancy; Constellation: Consultancy; Novartis: Consultancy. O'Brien: Amgen, Astellas, Celgene, GlaxoSmithKline, Janssen Oncology, Aptose Biosciences Inc., Vaniam Group LLC, AbbVie, Alexion, Verastem, Juno Therapeutics, Vida Ventures, Autolus, Johnson and Johnson, Merck, Bristol Myers Squibb, NOVA Research Company, Eli Lill: Consultancy; Kite, Regeneron, Acerta, Caribou, Gilead, Pharmacyclics, TG Therapeutics, Pfizer, Sunesis: Research Funding. Othus: Celgene: Other: Data safety monitoring board; Merck: Consultancy; Biosight: Consultancy; Glycomimetics: Other: Data safety monitoring board; Daiichi Sankyo: Consultancy. Litzow: Jazz: Other: Advisory Board; Pluristem: Research Funding; Amgen: Research Funding; Actinium: Research Funding; Omeros: Other: Advisory Board; Astellas: Research Funding; AbbVie: Research Funding; Biosight: Other: Data monitoring committee. Stone: Actinium: Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy; Arog: Consultancy, Research Funding; Astellas: Membership on an entity's Board of Directors or advisory committees; BerGen Bio: Membership on an entity's Board of Directors or advisory committees; Boston Pharmaceuticals: Consultancy; Bristol Myers Squibb: Consultancy; Elevate Bio: Membership on an entity's Board of Directors or advisory committees; Foghorn Therapeutics: Consultancy; Gemoab: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Consultancy; Innate: Consultancy; Janssen: Consultancy; Jazz: Consultancy; Novartis: Consultancy, Research Funding; Onconova: Consultancy; Syndax: Membership on an entity's Board of Directors or advisory committees; Syntrix/ACI: Membership on an entity's Board of Directors or advisory committees; Syros: Membership on an entity's Board of Directors or advisory committees; Aprea: Consultancy; Amgen: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy; Agios: Consultancy, Research Funding; Celgene: Consultancy; Macrogenics: Consultancy. Erba: AbbVie Inc; Agios Pharmaceuticals Inc; ALX Oncology; Amgen Inc; Daiichi Sankyo Inc; FORMA Therapeutics; Forty Seven Inc; Gilead Sciences Inc; GlycoMimetics Inc; ImmunoGen Inc; Jazz Pharmaceuticals Inc; MacroGenics Inc; Novartis; PTC Therapeutics: Research Funding; AbbVie Inc; Agios Pharmaceuticals Inc; Bristol Myers Squibb; Celgene, a Bristol Myers Squibb company; Incyte Corporation; Jazz Pharmaceuticals Inc; Novartis: Speakers Bureau; AbbVie Inc: Other: Independent review committee; AbbVie Inc; Agios Pharmaceuticals Inc; Astellas; Bristol Myers Squibb; Celgene, a Bristol Myers Squibb company; Daiichi Sankyo Inc; Genentech, a member of the Roche Group; GlycoMimetics Inc; Incyte Corporation; Jazz Pharmaceuticals Inc; Kura Oncology; Nov: Other: Advisory Committee.