Citations

Abstract Multiplexed Immunofluorescence (MxIF) enables detailed immune cell phenotyping, providing critical insights into cell behavior within the tumor immune microenvironment (TIME). However, signal integrity can be compromised due to the complex cyclic staining processes inherent to MxIF. Hematoxylin and Eosin (H&E) staining, on the other hand, offers complementary information through its depiction of cell morphology and texture patterns and is often visually cross-referenced with MxIF in clinical settings. In this study, we proposed a novel framework to align H&E and MxIF images for precise cross-modal cell feature validation. Using cell detection outputs from each modality as anchors, we formulated the multimodal image registration problem as point set alignment. Coherent Point Drift (CPD) is employed for initial alignment, followed by Graph Matching (GM) for refinement. Evaluations on ovarian cancer tissue microarrays (TMAs) demonstrate that our method achieves high alignment accuracy, enabling reliable validation of cell-level features across modalities for both restained and serial sections. Our results indicate that restained H&E enhances confidence in findings derived from MxIF. Additionally, we demonstrated the feasibility of generating high-quality virtual H&E images from MxIF data when restained H&E is unavailable, offering a viable alternative for integrated multimodal analysis.

AbstractBackgroundAccumulation of the amyloid‐β (Aβ) peptide into amyloid plaque is one of the key pathological markers of Alzheimer’s disease (AD). Apolipoprotein E (APOE) is known to modify AD risk and has been reported to influence Aβ accumulation in the brain in an isoform‐dependent manner. ApoE can be produced by various cell types in the brain, with astrocytes being the main producer. Increasing studies show that altering apoE levels can influence Aβ plaque pathology. However, it is not fully understood how apoE produced by specific cell types, such as astrocytes, contributes to amyloid pathology.MethodWe utilized mouse models expressing APOE isoforms in astrocytes and crossed them with 5xFAD mouse models of amyloidosis. We analyzed the changes to amyloid plaques and assessed the impact on cellular responses to amyloid plaques in condition of astrocytic APOE expression.ResultSpecific expression of APOE3 in astrocytes resulted in compact amyloid plaques and a large increase in plaque deposition, while the total plaque burden was reduced. Astrocytic APOE2 expression led to similar changes to amyloid plaques, but the fold change is lower comparing to that in astrocytic APOE3 models. Intriguingly, the total microglial response increased dramatically in condition of astrocytic APOE3 expression but not in condition of astrocytic APOE2 expression. Further, the ratio of plaque associated Lgals3/Iba1 is higher in condition of astrocytic APOE3 expression, indicating increased microglial activation. Additionally, astrocyte GFAP levels only increased in astrocytic APOE3 models, but not in astrocytic APOE2 models. Finally, APOE isoform effect on dystrophic neurites amount was also observed.ConclusionTogether, our study reveals an important role of astrocytic APOE on the deposition and accumulation of Aβ plaques as well as on Aβ‐associated downstream effects.

AbstractBackgroundThe efficacy of Calorie Restriction (CR) in enhancing cognition, promoting healthy aging, and extending lifespan is well‐established. Yet, it remains unclear whether the apolipoprotein E (APOE) genotype, a known modifier for aging and age‐related disorders, influences the beneficial effects of CR in countering aging.MethodsTo investigate this question, we utilized humanized APOE mouse models, which express APOE2, APOE3, or APOE4 alleles systematically (refer to as E2, E3, and E4 mice). These mice were subjected to either ad libitum (AL) feeding or 30% CR feeding, starting from 12 months and continuing up to 20 months of age (N = 11‐20/ genotype /group, mixed sex). We monitored energy expenditure using the Comprehensive Laboratory Animal Monitoring System (CLAMS). Additionally, we evaluated anxiety levels and memory capabilities through various behavioral tests. Finally, we collected brain, blood, and feces samples for transcriptomic, lipidomic, and microbiomic analyses.ResultsCLAMS measurements showed that CR significantly decreased the metabolic rate in E3 and E4 mice, but not E2 mice, during the non‐feeding period of the CR group, compared to the AL group. Furthermore, CR reduced anxiety and enhanced associative memory in E3 and E4 mice relative to the AL group. Brain transcriptomics revealed that CR upregulated the cholesterol synthesis pathway, potentially improving myelination‐related pathways in E3 and E4 mice. This finding was further validated by the increased staining intensity of myelin basic protein (MBP) observed in E3 and E4 mice from an independent cohort. In contrast, these effects were not pronounced in E2 mice. Additionally, while CR’s impact on the brain lipid profile was minor across all APOE genotypes, it significantly altered blood lipid profile of E2 mice, with minimal changes observed in E3 and E4 mice. Finally, in microbiomics, CR led to notable changes in the abundance of Bifidobacterium species in E3 and E4 mice and Lactobacillus species in E2 mice.ConclusionsOur study highlights the role of APOE genotypes in modulating the diverse effects of CR on cognition, brain transcriptomics, lipid metabolism, and the microbiome, providing a crucial foundation for considering APOE genotypes in developing prevention strategies for aging and age‐related disorders.

Purpose In lymphomas, the Deauville score (DS) standardizes 18F-FDG PET treatment response assessments. We assessed interobserver agreement of the DS and developed a quantitative PET-based parameter to minimize subjectivity of response assessments. Methods PET scans performed within the Children’s Oncology Group AHOD0831 study were analyzed. One hundred one scans obtained after the first cycle of chemotherapy (PET1) and 83 obtained after the second cycle (PET2) were eligible for inclusion. Each scan was assigned a DS by 2 nuclear medicine radiologists and a Hodgkin lymphoma index (HLI), defined as the ratio of the tumor’s SUVmax or SUVpeak to the liver’s SUVmean. Cohen κ coefficient measured the rate of agreement of the DS assigned by the 2 radiologists. Receiver operating characteristic curves and the Youden index were used with the consensus DS to identify an optimal HLI cutoff value to distinguish PET-negative from PET-positive images. For each HLI cutoff value, sensitivity, specificity, and accuracy were calculated. Results Interobserver agreement in DS was moderate (PET1: κ = 0.480, P < 0.001; PET2: κ = 0.428, P < 0.001). On PET1, the optimal cutoff values for HLImax were 1.19 for DS2/DS3 and 1.78 for DS3/DS4, and for HLIpeak were 1.19 for DS2/DS3 and 1.44 for DS3/DS4. On PET2 images, the corresponding values were 1.18, 1.58, 0.94, and 1.26. The most accurate predictor was HLImax on PET2 when scans were dichotomized as DS1–DS3 versus DS4–DS5 (accuracy, 92.8%; sensitivity, 100%; specificity, 91.8%). Conclusion The HLI provides an objective, quantitative measure of disease response and thus may improve interreader agreement for lymphoma response assessments.

Background: C10603/RATFIY was the first AML trial to show the benefit of adding a targeted agent to intensive chemotherapy for a specific genetically determined subset (Stone R et al, NEJM 2017). The addition of the multi-kinase inhibitor midostaurin (M) to chemotherapy in previously untreated adults with FLT3-mutant AML resulted in superior event-free (EFS) and overall survival (OS) compared to placebo (P) and led to the approval of this agent in combination therapy. Subsequently, additional targeted drugs including gilteritinib for relapsed/refractory FLT3-mutant AML and quizartinib plus chemotherapy in untreated adults with AML with FLT3-ITD disease have gained approval. Long-term follow-up after reporting of the primary endpoint, especially if met, is important in oncology. Objective: We report the EFS and OS data from C10603 using 10 years of follow up to determine the persistence of a midostaurin benefit and to assess the nature of late relapses or toxicity. Methods: C10603 enrolled 717 pts (360 on the M and 357 on the P arm; median age 47.8 years (range 18-61), 398 women (55.5%) of whom 51.7% were randomized to M and 59.4% to P (p=0.04), and 89% white) from 2011-2015 with previously untreated AML who had either a FLT3-TKD or ITD mutation with allelic ratio of &gt;0.05 to receive daunorubicin/cytarabine (3+7) induction (one reinduction permitted) followed by up to 4 consolidation cycles with cytarabine 3 g/m2 every 12h on days 1, 3 and 5. M (50 mg bid) or P was given orally on days 8-22 of each chemotherapy cycle as well as daily during one year of single-agent maintenance. Allogeneic transplantation (alloHCT) was employed at investigator's discretion; study drug was not continued post-HCT. Pts stayed on their randomized arm and were not re-randomized prior to maintenance. Pts were followed for relapse and survival after the end of protocol therapy, regardless of subsequent therapy, for 10 years. Log-rank tests, Kaplan-Meier methods, and Cox proportional hazard models were used to evaluate the treatment effect in EFS and OS, as well as the alloHCT effect. All p values are two-sided. Results: We have completed the 10-year FU on this trial and data collection has concluded. The median EFS was 8.2 months (95% CI, 5.5-11.4) on the M arm compared with 3.0 months for P (95% CI, 1.9-6.0) with a HR of 0.79 (95% CI 0.67-0.94, p=0.0067). Among the 420 CR pts who achieved complete remission (CR) by the protocol specified time of 60 days, 253 have had an event (death in 69 and relapse in 184); these events were relatively equal on each arm. OS, the co-primary endpoint, remained marginally superior for those randomized to M compared to P; the 10-year OS estimate was 43.7% (95% CI, 38.7-49.3%) vs 38.6% (95% CI, 33.6-44.4%) (p= 0.0485). The hazard ratios for OS favored randomization to M in each key biological subgroup (FLT3-ITD low or high allelic ratio or FLT3-TKD), but smaller subsets precluded statistical significance. There was a 10-year OS benefit in favor of M in men (p=0.005), but not women (p=0.9). A total of 414 transplants were performed: only 5 in the latter half of the follow-up period. Transplantation in CR1 was highly beneficial overall (10-year OS, 56% vs 35.8% without transplantation, p=0.001). Among those transplanted in CR1, randomization to M was marginally better than P (61.5% vs 49%, p=.064). After censoring for alloHCT in CR1, there was an OS trend in favor of M (51.8% v 48.0%, p=0.102). In CR1 patients who were randomized to maintenance therapy, M reduced the cumulative incidence of relapse in ELN 2017 favorable and intermediate risk pts, but not in those with adverse risk disease (HR 0.71, 0.47, and 1.01, respectively); maintenance M had no effect on OS. Only 3 pts relapsed after 5 years (all randomized to M). 25 pts randomized to M vs 13 P pts died after 5 years of follow-up. 5 pts on each arm died of a new primary cancer whereas 17 M and 5 P pts were coded as having died from treatment-related causes. None of the 3 pts who relapsed after 4 years had spliceosome mutations at diagnosis; whereas 18% (21/117) patients pts who had relapsed earlier had spliceosome mutations at diagnosis (p=0.419). Conclusions: The EFS benefit of randomization to midostaurin vs placebo when added to chemotherapy was maintained over time, although the benefit for OS was diminished, likely due in part to aging. Patient and disease factors differed between early vs late relapses, which could suggest the use of alternative therapies during distinct therapeutic stages.

Background: Inotuzumab Ozogamicin (InO) is an antibody-cytotoxin conjugate with high activity in B-cell acute lymphoblastic leukemia (B-ALL). InO targets the B-cell surface protein CD22, which is expressed in most B-ALL cases, albeit with great variability in expression levels. Emerging evidence suggest that this variation is associated with the stage of leukemia differentiation arrest [PMID: 21348573]. However, the exact relationship between CD22 expression and leukemia sensitivity to InO, particularly in the context of leukemia developmental state, remains unclear. Furthermore, our understanding of the molecular mechanisms regulating CD22 transcription in B-ALL is still incomplete. Methods: To comprehensively investigate the genomic basis of variability in leukemia CD22 expression and thus B-ALL sensitivity to InO, we performed a multi-omic characterization of 196 primary human B-ALL samples, using whole transcriptome sequencing (RNAseq), assay for transposase-accessible chromatin with sequencing (ATAC-seq), coupled with ex vivo profiling of InO sensitivity. Additionally, genomic editing studies were performed in Nalm6 and REH B-ALL cell lines, and patient derived xenograft (PDX) models were used for in vitro and in vivo validations. Results: Applying digital cytometry to leukemia bulk RNAseq data to infer the B-ALL developmental state, we found that blast cells with early Pre-pro-B-like signature had low levels of CD22 expression and were resistant to InO. As B-cell differentiation is controlled by stage-specific transcription factors (TFs), we performed a targeted CRISPR library screen of 1,639 TF genes and identified EBF1 as a key activator of CD22 expression (FDR=7.1x10-4). In primary B-ALL samples, EBF1 expression was significantly correlated with CD22 expression (R=0.69, P&lt;0.0001) and leukemia response to InO (measured as LC50, R=-0.42, P&lt;0.0001). In addition, TF footprint analysis of leukemia ATAC-seq data identified EBF1 as the most differentially activated TF comparing InO-sensitive and -resistant B-ALL cases (P=8x10-174). Blocking the EBF1 binding sites within the CD22 promoter by CRISPR interference resulted in a 50-fold and 49-fold decrease in cell surface CD22 expression, and a 22-fold and 25.7-fold increase in InO LC50 for Nalm6 and REH, respectively, confirming the direct impact of EBF1 on CD22 transcription and InO sensitivity. Because BCR::ABL1-positive ALL showed the greatest variability in InO sensitivity among all B-ALL subtypes, we further investigate the role of the EBF1/CD22 axis on InO sensitivity within this subtype. Unsupervised clustering of gene expression profiles revealed two distinct groups, namely BCR::ABL1 ALL with multilineage (BCR::ABL1-M) or lymphoid only (BCR::ABL1-L) involvement [PMID: 38153913]. Compared to BCR::ABL1-L, BCR::ABL1-M displayed markedly reduced CD22 expression (P=8.3×10-11) and resistance to InO (P=1.9×10-4), likely due to the lower expression and frequent somatic alteration of EBF1. Finally, we established PDX models for representative cases of BCR::ABL1-M and BCR::ABL1-L. Strikingly, InO treatment did not affect leukemia progression in the BCR::ABL1-M PDX model, whereas the BCR::ABL1-L PDX model achieved complete remission and has remained leukemia free to date. Conclusion: Collectively, these data demonstrate the direct impact of EBF1 on CD22 expression during B-cell development, and explain the heterogeneity of InO sensitivity, even within the same molecular B-ALL subtype.

Introduction: Epcoritamab (Epcor) is a novel subcutaneous CD3xCD20 bispecific antibody (bsAb) that is currently approved as monotherapy for the treatment of adults with relapsed or refractory (R/R) large B-cell lymphoma after ≥2 systemic therapies. The combination of Epcor with standard treatment regimens has been shown to be safe and efficacious; Epcor in combination with gemcitabine and oxaliplatin (Epcor+GemOx) has provided deep and durable responses with favorable survival outcomes in a transplant-ineligible R/R diffuse large B-cell lymphoma (DLBCL) patient (pt) population, of which 99% were from the US and Europe (EPCORE NHL-2; NCT04663347). Another CD3xCD20 bsAb, intravenous glofitamab, has been studied in combination with gemcitabine and oxaliplatin (Glofi+GemOx) in the randomized STARGLO trial (NCT04408638) and demonstrated benefit over rituximab plus GemOx (R-GemOx), despite not demonstrating superiority over R-GemOx in patients from the US and Europe. In the absence of head-to-head data, this study used matching-adjusted indirect comparisons (MAICs) to assess the comparative efficacy of Epcor+GemOx vs R-GemOx and vs Glofi+GemOx. Methods: Individual pt-level data from EPCORE NHL-2 arm 5 and aggregated data from pts in each of the STARGLO arms were used to conduct an MAIC. Logistic propensity score models were used to weight Epcor+GemOx-treated pts to create matched cohorts with the R-GemOx and Glofi+GemOx arms separately. Weighting was conducted based on the distribution of baseline characteristics and prognostic factors such as age, sex, Eastern Cooperative Oncology Group performance status, previous therapies, and primary refractory status. Overall response rate (ORR), complete response (CR) rate, progression-free survival (PFS), and overall survival (OS) were compared for Epcor+GemOx vs R-GemOx, and vs Glofi+GemOx. Results: A total of 103 pts treated with Epcor+GemOx (median follow-up: 13.2 months) were compared to 91 pts treated with R-GemOx and 183 pts treated with Glofi+GemOx (median follow-up: 20.7 months), although differences in median follow-up time limited comparisons of longer-term survival outcomes. Match-adjustment mitigated differences in baseline characteristics across the 3 cohorts. After adjustment, Epcor+GemOx demonstrated a significant 44.8% advantage in ORR over R-GemOx (85.4% vs 40.7%), with a 110% increase in the likelihood of achieving a response (odds ratio [OR] 2.1; 95% CI 1.6-2.8; P&lt;0.0001). Epcor+GemOx also demonstrated a significant 43.2% advantage in CR rate over R-GemOx (68.5% vs 25.3%), with a 170% increase in the likelihood of achieving a CR (OR 2.7; 95% CI 1.8-4.1; P&lt;0.0001). With the current follow-up, Epcor+GemOx demonstrated superior PFS vs R-GemOx (hazard ratio [HR] 0.37; 95% CI 0.22-0.63; P&lt;0.001), corresponding to a 63% reduction in the risk of progression. Median OS was not reached [NR] for Epcor+GemOx vs 13.9 months for R-GemOx, corresponding to a 43% reduction in the risk of mortality (HR 0.57 [95% CI 0.33-0.98]; P=0.04). After adjustment, Epcor+GemOx demonstrated a significant 15% advantage in ORR over Glofi+GemOx (83.3% vs 68.3%), with a 20% increase in the likelihood of achieving a response (OR 1.2; 95% CI 1.0-1.4; P=0.021). Epcor+GemOx demonstrated a trend toward higher CR rate than Glofi+GemOx (66.8% vs 58.5%; OR 1.1; 95% CI 0.90-1.5; P=0.277). Adjusted median PFS and OS for Epcor+GemOx, with limited follow-up and substantial censoring, was 12.9 months and NR, respectively. For Glofi+GemOx with longer follow-up, PFS and OS were 13.8 months and 25.6 months, respectively. Conclusions: Results show significantly superior efficacy for all outcomes with Epcor+GemOx vs R-GemOx from STARGLO. Epcor+GemOx also provided superior ORR and a trend toward higher CR rates vs Glofi+GemOx, indicating potential for better long-term efficacy outcomes. The Epcor+GemOx survival data are still maturing given shorter follow-up time, preventing a robust comparison of survival vs Glofi+GemOx. Findings support the efficacy of Epcor+GemOx as an alternative therapeutic regimen in transplant-ineligible patients with R/R DLBCL.

Introduction: Epcoritamab, a novel subcutaneously administered CD3xCD20 bispecific antibody (bsAb) being developed as a core therapy across several lymphoma subtypes, is currently approved for the treatment of adults with different types of R/R LBCL after ≥2 systemic therapies. The combination of epcoritamab with standard treatments has been shown to be safe and efficacious; epcoritamab in combination with gemcitabine and oxaliplatin (Epcor+GemOx) has provided deep and durable responses with favorable survival benefits in a transplant-ineligible R/R DLBCL study population, of which 99% was from the United States and Europe (EPCORE NHL-2; NCT04663347). The rituximab plus gemcitabine and oxaliplatin (R-GemOx) regimen has been a widely used treatment for patients with R/R DLBCL ineligible for transplant, albeit with suboptimal efficacy outcomes. In the absence of direct comparisons of these regimens, this study assessed the comparative efficacy of Epcor+GemOx vs R-GemOx in patients with R/R DLBCL ineligible for transplant. Methods: Individual patient-level data (IPD) from EPCORE NHL-2 arm 5 were compared to 2 sources of clinical practice data for patients with R/R DLBCL treated with R-GemOx: published data from Cazalles et al (2021) and IPD from the US-based COTA electronic health record database. The Cazalles study reports the results of a large retrospective analysis of patients with R/R DLBCL treated in 2 academic centers in France. The COTA database includes de-identified IPD with demographic and clinical information from numerous academic and community clinical sites in the US. For the comparison to Cazalles, logistic propensity score models were used to weight the Epcor+GemOx cohort to create match-adjusted distributions of baseline characteristics with the R-GemOx cohort in Cazalles. For the comparison to COTA, inverse probability of treatment weighting was employed to balance covariates between the Epcor+GemOx and R-GemOx cohorts. Analyses were restricted to chimeric antigen receptor T-cell therapy (CAR T)-naive patients from EPCORE NHL-2, as the comparator cohorts did not include patients treated with CAR T. Overall response rate (ORR), complete response (CR) rate, progression-free survival (PFS), and overall survival (OS) were compared for Epcor+GemOx vs R-GemOx. Results: A total of 74 patients treated with Epcor+GemOx (median follow-up: 13.2 months) were compared to 196 R-GemOx-treated patients from Cazalles et al (median follow-up: 22 months). After match-adjustment, Epcor+GemOx (ORR 86.8%) demonstrated significantly higher ORR, corresponding to a 48.5% advantage over R-GemOx (ORR 38.3%) with an odds ratio (OR) of 2.3 (95% CI 1.8-2.9; P&lt;0.0001). Adjusted CR rate was also significantly higher with Epcor+GemOx vs R-GemOx (71.2% vs 32.7%; 38.6% difference; OR 2.2 [95% CI 1.6-3.0]; P&lt;0.0001). Median PFS was significantly longer with Epcor+GemOx (26.7 months) vs R-GemOx (4.8 months; hazard ratio [HR] 0.38 [95% CI 0.22-0.67]; P&lt;0.001). Median OS was not reached (NR) for Epcor+GemOx vs 10.0 months with R-GemOx (HR 0.54 [95% CI 0.29-1.0]; P=0.05), corresponding overall to a 62% reduction in the risk of a progression event and a 46% reduction in the risk of mortality with Epcor+GemOx vs R-GemOx. A total of 72 patients were treated with R-GemOx in COTA (median follow-up: 7.5 months) and compared to 74 Epcor+GemOx patients. After adjustment, ORR was significantly higher with Epcor+GemOx vs R-GemOx (88.5% vs 35.6%; OR 2.5 [95% CI 1.8-3.4]; P&lt;0.0001). Adjusted CR rate was also significantly higher with Epcor+GemOx (63.9% vs 10.2%; OR 6.3 [95% CI 3.1-12.7]; P&lt;0.0001). Adjusted median PFS was significantly longer with Epcor+GemOx (11.2 months) vs R-GemOx (2.4 months; HR 0.23 [95% CI 0.15-0.36]; P&lt;0.0001). Adjusted median OS was also significantly longer with Epcor+GemOx (21.6 vs 8.3 months; HR 0.47 [95% CI 0.30-0.74]; P=0.002), corresponding overall to a 77% reduction in the risk of a progression event and a 53% reduction in the risk of mortality with Epcor+GemOx vs R-GemOx. Conclusions: In this indirect treatment comparison analysis,Epcor+GemOx provided significantly superior efficacy benefits in terms of ORR, CR, PFS, and OS vs standard-of-care R-GemOx. While subject to the limitations of comparisons outside of controlled trials, findings indicate the compelling efficacy of Epcor+GemOx as a novel therapeutic option for transplant-ineligible patients with R/R DLBCL.

Introduction: Inotuzumab ozogamicin (INO) is an antibody targeting CD22 conjugated with a cytotoxic antitumor antibiotic (calicheamicin) approved for treatment of relapsed/refractory CD22 positive B-cell acute lymphoblastic leukemia (ALL) (Kantarjian et al. NEJM 2017). CD22 is expressed on the surface of lymphoblasts in ALL (~95%). Young adult patients (pts) 18-39 years (yrs) treated on the pediatric regimen CALGB 10403 resulted in a 3-yr event-free survival (EFS) of 59% (95% CI: 52-67%) and an estimated 3-yr overall survival (OS) of 73% (95% CI: 68-78%) (Stock et al. Blood 2019). Alliance A041501(NCT03150693), a phase 3 NCTN sponsored cooperative group trial was conducted to determine if the addition of INO to the CALGB 10403 pediatric regimen would significantly improve EFS. Methods: Eligibility included pts 18-39 years with newly diagnosed CD22 positive ALL, defined as baseline expression in &gt; 20% of lymphoblasts by local institution. Pts with Burkitt-type ALL, BCR::ABL1 positive ALL, or Down syndrome were excluded. Eligible pts received the CALGB 10403 regimen modified to omit extended induction, include dexamethasone as opposed to prednisone as steroid backbone, cap the pegaspargase dose to 3750 units, and adding rituximab for pts with CD20 expression (&gt; 20%). An amendment added blinatumomab for minimal residual disease (MRD) positivity. Pts achieving a complete remission (CR/CRi) or partial remission (PR) were eligible for randomization. Following a 6 pt safety run-in with INO, pts were randomized 1:1 to receive INO or continue CALGB 10403 backbone. Two cycles of INO (1.5 mg/m2/cycle) were administered following induction in the experimental arm. Pts were stratified by age, disease status post induction (M0/M1 vs M2), CD20 status, and LDA Card, which tests for the Ph-like status. The primary endpoint was to determine if the addition of INO would improve the EFS of the pediatric regimen CALGB 10403 without censoring for stem cell transplant (SCT). Key secondary endpoints included the impact of INO on disease-free survival (DFS), OS, and MRD. The Alliance Data and Safety Monitoring Board halted enrollment after 273 out of a planned 341 pts were registered because of increased grade (gr) 5 events in the INO arm compared with the control arm. Results: 273 pts were enrolled between 6/15/2018, and 5/24/2022. Median age was 27.0 yrs, 65.2% were White, 30.4% were Hispanic, and 63.4% were male. Baseline CSF analysis revealed 14% with CNS-2/3 disease. The overall CR rate was 86.8% (82.8-90.8%). 46 pts were not randomized due to death (5), withdrawal (6), ineligibility (3), toxicity (5), receipt of non-protocol therapy (8), progression (5), and other (14). 227 eligible pts were randomized 1:1 to receive INO (N=111) or not (N=116)). For randomized pts, 92.5% achieved M0/M1 marrow status, 48.9% had a positive LDA Card defining Ph-like ALL, 50.7% were CD20 positive. Only 36 pts (13%) received a SCT. With a median follow up of 28.3 months for randomized pts, 3-yr EFS was 69.0% (59.1-80.5%) for the INO arm and 66.7% (57.1-78.1%) for the control (HR=0.97; 0.58-1.63). Similarly, the 3-yr OS was 79.4% (71.0-88.7%) for the INO arm and 80.3% (71.9-89.6%) for the control (HR=1.05; 0.55-2.01). The MRD undetectable rate at Course II Day 56 was 80.6% in the INO arm and 74.2% in the control arm. Univariate analysis suggests improved EFS with INO in pts with a positive LDA card (Ph-like ALL) and of Hispanic ethnicity. There were 22 gr 5 events, 7 occurred prior to randomization. Of the 15 gr 5 events on the randomized cohort, 12 were reported in the INO arm and 3 in the control arm. Of the 12 gr 5 events in the INO arm, all occurred during intensive consolidation courses complicated by prolonged pancytopenia infection/sepsis (8), hepato-biliary in setting of infection (2), multi-organ failure (1), or post-surgical complication (1). These events occurred after INO during Course II (3), Course III (5), or Course IV (4). Conclusions: Although this trial did not meet the primary EFS endpoint for the addition of INO to the pediatric regimen CALGB 10403, these data provide compelling evidence for continued use of pediatric regimens in young adults with ALL as the EFS and OS compares favorably with prior published results. INO may still be efficacious if late toxicity can be mitigated. A pilot study is planned that will decrease INO dose, add 2 cycles of blinatumomab and strict infectious prophylaxis guidelines. Support: U10CA180821, U10CA180882

Background/Objectives: Respiratory syncytial virus (RSV) causes symptoms similar to a mild cold for adults, but in case of infants, it causes bronchitis and/or pneumonia, and in some cases, mortality. Mucosal immunity within the respiratory tract includes tissue-resident memory T (TRM) cells and tissue-resident memory B (BRM) cells, which provides rapid and efficient protection against RSV re-infection. Therefore, vaccine strategies should aim to generate mucosal immune responses. However, the interactions between RSV vaccines and mucosal immune responses within the respiratory tract are poorly understood. We evaluated a mucosal immune system following immunization by RSV vaccine with poly-sorbitol transporter (RSV-PST), a nanoparticle adjuvant. Methods: We intranasally immunized the RSV-PST and identified the systemic and mucosal immune responses. Furthermore, we challenged with RSV A2 strain after immunization and investigated the protective effects. Results: Consequently, antigen-specific CD8+ TRM cells were markedly elevated in the lung parenchyma, yet exhibited impaired cytokine expression. In contrast, humoral immunity, with systemic antibody production from serum, but not in the respiratory tract, was significantly increased by RSV-PST immunization. Interestingly, the production of respiratory mucosal antigen-specific IgG after RSV A2 challenge dramatically increased in the bronchoalveolar lavage fluid (BALF) of the RSV-PST immunized group in the presence of FTY720, and the lung-infected RSV titer was significantly lower in this group. Furthermore, after RSV A2 challenge, CD69+ IgG+ BRM cells were significantly increased in lung tissues in the RSV-PST group. Conclusions: The RSV-PST vaccine has protective effects against RSV infection by promoting both systemic and local humoral immunity rather than cellular immunity.