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Introduction The major primary genetic events in multiple myeloma (MM) include translocations of immunoglobulin heavy chain (IgH) and a hyperdiploidy (HRD) karyotype (Kuehl, 2002). The main drivers of pathogenesis in HRD MM are unknown (Fonseca, 2003), therefore further research is needed in this subgroup. Translational research in HRD MM has relied on analysis of genomic and transcriptomic alterations, however changes at the genome and transcriptome level do not always correlate directionally with protein abundance. Because proteins are considered the main and final effectors of most cellular processes, proteogenomics can improve our understanding of the drivers of HRD MM. We employed it here to identify potential biomarkers in HRD MM and determine whether any given trisomy may lead to a selective advantage. Methods: Protein and mRNA were extracted from CD138+ cells from 47 HRD MM and 14 t(11;14) MM samples. RNA-seq data was processed using MAPR-Seq pipeline using default parameters and gene-wise raw counts were extracted for each sample. Proteomics data was processed using Specranaut and protein-wise intensities were extracted for each sample. A generalized linear model configured with negative binomial distribution was used to analyze gene-wise count data in edgeR software. Genes with an adjusted p-value of <=0.05 were considered significantly differentially expressed. Protein intensity data were normalized using trimmed mean of M-values and log2 transformed. A generalized linear model configured with Gaussian distribution was used to compare protein intensities between the groups. Proteins with an adjusted p-value <= 0.05 were considered significantly differentially expressed. Two separate rank lists for protein and mRNA data were generated for pathway analysis. Results When comparing our small cohort of HRD MM patient samples to those with t(11;14) MM, out of approximately 16,600 total transcripts and 9,700 proteins evaluated we identified approximately 2,100 significantly variant transcripts and 500 significantly variant proteins in HRD MM. GSEA pathway analysis of the transcriptome and proteome revealed significantly upregulated translational and ribosomal processing pathways in HRD MM. Transcriptional MYC target pathways were also significantly upregulated. RNAseq revealed significantly higher expression of MYC (Rank 24.5, p=5.3E-6) in HRD MM. It is known that patients with t(11;14) MM have increased expression of CCND1 (Kuehl and Bergsagel, 2012). As expected, we found that the HRD MM subgroup had significantly lower expression of CCND1 compared to the t(11;14) MM subgroup (Rank -79.9, p=2.8E-21) and this was also true at the protein level (Rank -21.7, p=2.2E-5). The most significantly abundant protein in the HRD MM subgroup compared to t(11;14) MM was BAHD1, which is a protein that targets H3K27me3 and recruits transcriptional co-repressors (Fan, 2020). BAHD1 has been shown to repress erythroid genes and may recruit HDAC5, which plays a role in osteoblast differentiation (Rank 72.3, p=2.9E-20; Xu, 2021). The second most abundant protein in HRD MM was CKS2, which binds to the catalytic subunit of cyclin-dependent kinases (CDKs) and therefore positively regulates cell proliferation, invasion, and migration and has been shown to be implicated in tumor progression in several solid tumors (Rank 72.3, p=2.9E-20; You, 2015). TRIM proteins promote tumorigenesis and cancer development. TRIM14 mediates cancer development through mediating the JAK/STAT, PI3K/AKT, NFkB, and p53 pathways and was found to be significantly higher in HRD MM (Rank 70.6, p=9.0E-20; Huang, 2022). We also found increased protein abundance of LAMP5 in HRD MM (Rank 20.1, p=6.0E-5). LAMP5 may play an important role in MM progression and has been shown to be highly expressed in patients with mixed-lineage leukemia and is associated with a poor prognosis (Wang, 2023; Gracia-Maldonado, 2022). We identified many proteins (not all discussed here) that have not been well described in HRD MM and thus may be biomarkers/targets of disease pathogenesis of this subgroup. Conclusion Proteins are the final effectors of most cellular processes. Proteogenomics can improve our understanding of the drivers of HRD MM. Using a proteogenomic approach we identified proteins that may lead to selective advantage and/or pathogenesis of trisomies in HRD MM.

Introduction: Ven is a BCL2 inhibitor that has shown clinical efficacy in RRMM patients (pts) particularly those that harbor t(11;14). Ven has been evaluated in clinical trials as a single agent, in combination with dexamethasone (dex), immunomodulatory drugs (IMiD), proteasome inhibitors (PI), and anti-CD38 monoclonal antibodies (MAb) yet its place in the therapeutic landscape remains in question. In this retrospective analysis, we aim to evaluate the real-world efficacy of Ven-based regimens in RRMM pts treated outside of a clinical trial across the 3-site MCCC. Methods: We retrospectively analyzed the medical records of pts with RRMM treated with Ven-based regimens between January 2015 and October 2023 at the MCCC. Refractoriness was defined by progression on or within 60 days of stopping treatment. Categorical variables were compared with Chi-square tests and continuous variables were compared with t-tests. Outcomes were estimated using the Kaplan-Meier method and curves were compared between the groups using log-rank tests. Results: 83 pts were included in the analysis. The median age was 71 (39-93), 63% were male, 93% were white, 27% had ISS III, 18% had high risk cytogenetics (HRCyto), 76% had t(11;14), the median prior lines of therapy (LOT) was 4 (1-15), 68% received ≥ 4 prior LOT, 87% received prior autologous transplant, 58% were triple-class refractory (TCR), 64%/23% were penta-drug exposed/refractory (PDE/R), 8% received prior BCMA-directed therapies (BDT), 58% received Ven+dex, 25% received Ven+PI +/-dex, 6 % received Ven+anti-CD38 MAb+/-dex and 11% received Ven+other. The median follow-up time from start of a Ven-based regimen was 29 months (mo). The median Ven dose was 800mg (20-1600) with 25% of pts receiving Ven ramp-up dosing. The overall response rate (ORR) to a Ven-based regimen was 58% and was 64% for pts with t(11;14) and 40% for pts without t(11;14); p=0.06. Ven-treated pts with HRCyto had inferior PFS (3mo) and OS (8mo) compared to patients who did not have HRCyto who had a PFS of 9mo (p=0.020) and OS of 80mo (p<0.001). The ORR for TCR and PDR pts were 52% and 42%, respectively. No significant ORR differences were noted across the different Ven-based regimens (p=0.32). The median PFS for pts with t(11;14) was 10mo compared to 2mo for pts w/o t(11;14); p=<0.001. The median OS for pts with t(11;14) was 80mo compared to 10mo for pts without t(11;14); p=0.001. Ven-treated pts who received 1-3 prior LOT has superior ORR, median PFS, and median OS; 89%, 25mo, and 99mo, respectively, compared to pts who received ≥4 prior LOT who achieved an ORR of 43% (p<0.001), median PFS of 5mo (p<0.001) and median OS of 25mo (p<0.001). Ven-treated pts that were TCR had inferior PFS (5mo) and OS (26mo) compared to pts who were not TCR who achieved a PFS of 12mo (p<0.001) and a median OS of 80mo (p=0.02).Ven-treated pts that were PDR had inferior PFS (4mo) and OS (22mo) compared to pts who were not PDR who achieved a PFS of 9mo (p<0.001) and a median OS of 80mo (p=0.02).Ven-treated pts who received prior BDT (n=7) achieved an ORR of 29% and had a median PFS and OS of 2mo and 6mo, respectively on a Ven-based therapy. 59 pts received additional therapy in the post Ven-progression setting. The ORR to post-Ven progression therapies was 53% (n=31/59), the median PFS was 9mo and median OS was 35mo. The most common post-Ven progression regimens used were PI-based (n=16; ORR=56%), anti-CD38 MAb-based (n=14; ORR=50%), BDT (n=12; ORR=83%), selinexor-based (n=3; ORR=0%) with BDT resulting in highest ORR (p=0.048) and PFS (p=0.005). Conclusions: Ven-based regimens are effective in heavily pre-treated pts with RRMM however they are more effective when used within 1-3 prior LOT, in pts with t(11;14), and in pts without HRCyto, TCR or PDR MM. BDT appear to be the most efficacious therapies in the post-Ven progression setting.

Introduction: HIV-associated diffuse large B-cell lymphoma (HIV-DLBCL) is a significant complication in HIV-positive individuals, presenting unique clinical challenges and a poorer prognosis compared to patients with de novo DLBCL. Epstein-Barr Virus (EBV) status is a critical factor influencing the pathogenesis, clinical behavior, and therapeutic responses in these lymphomas. Plasmablastic lymphomas (PBL) have shared some overlapping genomic abnormalities with HIV-DLBCL including MYC rearrangements. This study aims to elucidate the differences in the genetic profiles and pathway activations between EBV(+) and EBV(-) HIV-DLBCL through comprehensive genomic profiling. Methods: Cases of DLBCL were identified in patients living with HIV from a multi-institute cooperative group. Cases of Burkitt lymphoma and PBL were excluded. We performed whole exome sequencing (WES) on 106 tumors of HIV-DLBCL and RNA sequencing on 39 tumors and mapped the reads to hg38 reference genome using BWA and STAR, respectively. EBV status of cases was determined by in situ hybridization and/or reads mapped on EBV genome in sequencing data. Somatic mutations were identified using variant callers (Strelka2, Mutect2) with WES data. For those mutated genes in COSMIC, allele frequency cutoff was set at 0.03. Mutations with an artifact score larger than 0.7 in SOBDetector and those located in segmental duplications were further removed. They were annotated with Ensembl Variant Effect Predictor, manually checked, and plotted with maftools. RNAseq read counts aligned to each gene were obtained by featureCounts and DEseq2 was used for differential expression (DE) analysis between EBV positive and negative groups. Pathway analysis with the DE genes was performed using GSEA. FISH analysis was performed using MYC, BCL2, and BCL6 break-apart probes. Results: There were 41 cases of EBV(+) HIV-DLBCL and 65 cases of EBV(-) HIV-DLBCL. FISH of EBV(+) HIV-DLBCL identified 42% (3/7) with MYC rearrangement (MYCr), none with BCL2 rearrangements (BCL2r) (0/6), and 33% (2/6) positive for BCL6 rearrangement (BCL6r) with 1 tumor having a MYCr/BCL6r. For EBV(-) HIV-DLBCL, there were 35% with a MYCr (6/17), 18% with BCL2r (2/11), and 27% with a BCL6r (3/11) with 2 tumors with MYCr/BCL6r, and 1 tumor with MYCr/BCL2r/BCL6r. The most frequent mutations seen in EBV(+) HIV-DLBCL were STAT3 (32%), DDX3X (22%), and TP53 (15%). For EBV(-) HIV-DLBCL, the most frequent mutations were KMT2D (25%), TP53 (23%), GNA13 (22%), and TET2 (22%). Pathways that were most commonly associated with EBV(+) HIV-DLBCL were JAK/STAT (42%) (STAT3, JAK1) and NF-kB (39%)(DDX3X, TNFAIP3) while EBV(-) HIV-DLBCL was associated with epigenetic modifiers (62%)(KMT2D, TET2, EP300), JAK/STAT (45%)(SOCS1, JAK3) and PI3K/mTOR (40%)(GNA13, MTOR). Significant disparities between EBV(+) and EBV(-) were KMT2D (24% vs 50%, P=0.0025), TET2 (10% vs 26%, P=0.008), SOCS1 (29% vs 39%, P=0.04), DDX3X (15% vs 5%, P=0.03), and GNA13 (5% vs 24%, P=0.001). RAS mutations (KRAS, NRAS) were infrequent in HIV-DLBCL (EBV(+), 12%; EBV(-), 6%), in contrast to prior studies of PBL. Gene expression profiling showed enrichment of MYC targets, oxidative phosphorylation, and the mTORC pathway in EBV(+) as compared to EBV(-) HIV-DLBCL. Conclusion: EBV(+) HIV-DLBCL show a distinct mutational profile compared to EBV(-) HIV-DLBCL, with EBV(+) cases showing frequent mutations with STAT3 and DDX3X in contrast to EBV(-) cases with frequent mutations associated with epigenetic modification pathways (KMT2D, TET2). These genetic profiles underscore the need for tailored therapeutic approaches depending on EBV status. Although the analysis is limited and requires confirmation in a larger cohort, this is the largest study at present evaluating these tumors.

Introduction Monoclonal antibodies (MoAbs) directed against CD38 are a mainstay in multiple myeloma (MM). Downregulation of CD38 expression is a resistance mechanism of antigenic escape, however, cell surface expression may return. While this tumor cell plasticity is likely driven by epigenetic mechanisms, it is unknown if MM cells can develop permanent resistance to anti-CD38 MoAb by acquiring genomic events leading to biallelic disruption of CD38 thus precluding re-treatment. Here, we report biallelic loss of CD38 as a recurrent mechanism of resistance, often via convergent evolution where distinct subclones are advantaged towards the same selective pressure. Methods We interrogated two sets of patients (Mayo Clinic; n = 31, Calgary University; n =19) with relapse following anti-CD38 MoAbs. Two additional cases of interest were selected from Heidelberg University. Whole genome sequencing (WGS, 60-100x) or whole exome sequencing (WXS), flow cytometry (flow), and bulk RNAseq were used to validate the effect of genomic events on CD38. Missense mutations predicted to affect CD38 MoAb binding were validated with site-directed mutagenesis of a CD38 plasmid, transduction into K562 MM cells, and CD38 MoAb binding assays. Results The prevalence of biallelic inactivation of CD38 at anti-CD38 MoAb relapse was 6% (3/50). An additional selected biallelic event was noted in the Heidelberg set. Each case is described in detail: MM-19 (Calgary) received daratumumab (Dara), lenalidomide, and dexamethasone (Dex), and then had a second exposure to Dara, following relapse. At this second relapse, WGS was performed on two independent extramedullary disease localizations in the liver. Both samples had unique, large deletions (>3 Mb) on chromosome 4 coupled with additional unique focal deletions involving CD38. Flow confirmed the presence of CD138+/CD38- plasma cell populations in both sites. A second case of convergent evolution was seen in a patient (Mayo) after seventh-line Dara/Len/Dex. WGS revealed a common deletion encompassing CD38. On the remaining allele, one subclone had a structural variation-mediated loss of CD38(cancer cell fraction; CCF 40%) while another harbored an L153H missense mutation (CCF 60%). Flow confirmed presence of two CD138+ clones; one with diminished CD38 expression. L153H was functionally validated to abrogate Dara binding, while maintaining CD38 expression. The third sample was collected after fifth-line Dara and sixth-line Dara/Bortezomib/Dex (Heidelberg) and represents another case of convergent evolution with a common loss of chromosome 4 and two subclones detected by WGS (P98Lfs*12, CCF 39% resulting in biallelic inactivation; R140G, CCF 61%). Bulk RNAseq revealed, in comparison to NDMM from CoMMpass, CD38 expression below the first decile. Notably, the R140G variant reduced binding affinity to Dara but not to Isatuximab (Isa). A fourth case (Mayo) relapsing after 6 months of Dara-based therapy similarly had a focal deletion of CD38 with an L18Sfs*16 frameshift deletion on the remaining allele associated with a 4.35-fold reduction in CD38 expression by RNAseq compared to pre-treatment. Interestingly, in 3/4 cases the CD38-negative clone emerged after a second exposure to anti-CD38 MoAb, suggesting emergence with the first exposure and then selection during the second. One other monoallelic event (C275Y; Heidelberg) was detected post-Isa. Copy number of the alternate allele is not known given targeted sequencing methodology, but the variant was seen to reduce binding affinity to both Dara and Isa. The prevalence of monoallelic loss of CD38 in newly diagnosed MM from MMRF CoMMpass was 7% (50/701) and two patients had mutations in CD38, but there were no cases of biallelic loss suggesting these events are driven by treatment pressure. Conclusion Distinction of the mode of CD38 loss is valuable for predicting outcome of re-challenge to anti-CD38 MoAbs. We see here an estimated 5-10% of anti-CD38 MoAb relapses are characterized by genomic antigen escape. Results here are in line with antigen escape to BCMA- and GPRC5D-directed immunotherapies (Lee et al, Nat Med 2023), suggesting that acquired antigen escape resulting from prolonged exposure to the selective pressures of immunotherapy is a recurrent mechanism of resistance in MM. Moreover, in select cases, non-overlapping resistance mutations provide rationale for switching agents at second exposure.

Introduction CD19-directed CAR T-cell therapies are an important option for the management of relapsed/refractory (R/R) DLBCL. Studies suggest that ~50% of pts receiving CAR T-cell therapies will relapse within 6 months, with an estimated overall survival (OS) of only 5 months. Additionally, 25-35% of pts do not receive subsequent treatment, indicating a high unmet need. CD19 loss is a potential mechanism of resistance to CAR T-cell therapies; thus, treatments that target alternate B-cell antigens are an attractive option. Here, we report for the first time the primary analysis of the ELM-1 expansion cohort investigating the efficacy and safety of odronextamab, a CD20×CD3 bispecific antibody, in pts with R/R DLBCL progressing after CAR T-cell therapy (NCT02290951). Methods Pts aged ≥18 with DLBCL and disease progression after CAR T-cell therapy received intravenous odronextamab weekly in 21-day (D) cycles during Cycles (C) 1-4, with steroid prophylaxis and step-up dosing in C1 (described previously), followed by 160 mg on D 1, 8, and 15 of C2-4. After C4, odronextamab maintenance treatment continued at 320 mg Q2W until disease progression or unacceptable toxicity. Pts with complete response (CR) for ≥9 months transitioned to Q4W dosing. All pts received infection prophylaxis. The primary analysis was conducted when all pts had completed ≥9 months of follow-up. Primary endpoint was objective response rate (ORR), as assessed by independent central review (ICR) according to the Lugano classification. Key secondary endpoints included duration of response (DOR), progression-free survival (PFS), and OS. Exploratory endpoints included immune biomarker assessment. Results As of January 22, 2024, 60 pts were treated and evaluable for efficacy and safety, with median follow-up of 16.2 months. Prior CAR T-cell therapies were axi-cel (50%), tisa-cel (12%), liso-cel (10%), and not specified (28%). Median time since prior CAR T-cell therapy was 6.5 months (range 1.2-46.2). Median age was 63 years (range 27-82; aged ≥75 years: 10%), and 65% were male. Pts had received a median of 3 prior lines of therapies (range 2-9); 77% of pts were refractory to their last therapy, 77% were double refractory, and 72% were refractory to prior CAR T-cell therapy. 48% of pts relapsed within 90 D of CAR T-cell therapy, and 67% relapsed within 180 D. Of the 20 pts with available tumor biopsies at baseline, 10 were CD19(-) and only 2 were CD20(-). 92% of pts completed C1 and 52% completed ≥4 C of treatment. The median duration of treatment was 12 weeks (range 0.7-154.1). The ORR and CR rate by ICR were 48% and 32%, respectively, and were consistent across pts with high-risk features and across prior CAR T products. ORR in pts relapsing in ≤90 D was 21% (6/29) and in pts relapsing in ≤180 D was 33% (13/40). ORR was observed even in pts with low CD20. Median DOR was 14.8 months (95% CI 2.8-not estimable [NE]) and median duration of CR was not reached (NR) (95% CI 3.3-NE); the probability of maintaining CR for 24 months was 68%. Median PFS was 4.8 months (95% CI 2.6-5.4) and median OS was 10.2 months (95% CI 4.6-15.8). Median PFS and OS in complete responders was NR. T-cell counts increased at Week 14 and demonstrated a functional phenotype (CD69 expression and TEMRA count), which was confirmed by ex vivo stimulation. T-cell expansion was observed regardless of CAR T product or time from CAR T administration. The most common TEAE was CRS (any grade [G]: 48%; G1: 25%; G2: 23%; G≥3: 0%). G≥3 TEAEs occurred in 77% of pts (most common: neutropenia 17%, anemia 13%, and neutrophil and white blood cell count decrease 10% each). Five pts (8%) permanently discontinued odronextamab due to AEs (COVID-19, pneumonia, encephalopathy, epilepsy, and gait disturbance [n=1 each]). There was one treatment-related death (COVID-19 pneumonia). No cases of ICANS were reported. G≥3 infections occurred in 12 pts (20%); 2 were due to COVID-19. No cases of tumor flare or TLS were reported. Conclusions ELM-1 is the only study to prospectively evaluate efficacy and safety of a CD20×CD3 bispecific antibody in pts with R/R DLBCL progressing after CAR T-cell therapy. Odronextamab monotherapy was associated with encouraging efficacy and generally manageable safety in a setting with limited treatment options and historically dismal outcomes. Efficacy was observed even in pts relapsing in ≤90 D, supporting the potential of odronextamab as an accessible, off-the-shelf option in the post-CAR T setting.

Introduction: Multiple myeloma (MM) with t(11;14)(q13;q32), resulting in CCND1;IGH rearrangement, remains the only subset amenable to targeted therapy with the BCL2 inhibitor, Venetoclax. Nevertheless, not all patients with this translocation respond to treatment and some progress early after initial response. The mechanisms behind this clinical heterogeneity are largely unknown. Methods: To investigate mechanisms of heterogeneity in response to Venetoclax, we interrogated 44 whole genome sequencing (WGS) and 24 whole exome sequencing data from a training cohort including 33 patients with t(11;14) MM treated with Venetoclax at the Mayo Clinic. In a validation cohort, we extracted single nucleotide variants (SNV) and indels from 17 MM patients with t(11;14) with available RNAseq data treated with Venetoclax at Emory University. Results: In the training cohort the median number of lines of therapy was 4 and Venetoclax drug regimens included combinations with dexamethasone, proteasome inhibitors, anti-CD38 agents, and immunomodulatory agents. After a median follow up of 30 months, the median progression free survival (PFS) was 9 months, and 13 patients (39%) achieved a complete remission (CR) to therapy, while 9 (27%) were refractory (i.e. no response or progressed within the first 60 days). For our driver discovery analysis, we integrated SNV, indels, copy number variants (CNV) and structural variants (SV). Deletion 17p (del17p) or TP53 mutation, MCL1 gain/amp, and hyper-APOBEC did not correlate with PFS in our cohort (p=0.59, p=0.71, and p=0.05, respectively). In contrast, mutations involving the MAPK pathway (NRAS, KRAS, BRAF, FGFR3) displayed the strongest association with short PFS, which was retained after adjusting for del17p/TP53 mutations, and 1q gain/amp (HR: 4.76, CI: 1.8-12.9, p=0.002). The association between suboptimal response and resistance to Venetoclax in MM patients with MAPK pathway mutations (n=7) was also observed in our validation cohort from Emory University (p=0.046). This is in line with what has been reported in functional studies in acute myeloid leukemia, where RAS pathway promotes MCL1 under the selective pressure of Venetoclax (Zhang et al. Signal Transduct Target Ther 2022). While MAPK mutations explained most cases of refractory patients (86%), the mechanisms through which initially responding patients subsequently progressed remain unclear. To investigate this, we interrogated 10 patients with pre- and post-treatment samples collected at disease progression (PD). We identified genomic events acquired/selected at PD of genes involved in the anti-apoptotic MCL1/BCL2 and MAPK pathways in 6/10 cases. One patient was refractory to Venetoclax and had double minutes involving BCL2, which caused multiple focal amplifications (>30 copies), likely reflecting extrachromosomal DNA. Another patient progressed with an acquired, focal deletion on BCL2L11. In two patients, the progressing clones harbored mutations in MAPK pathways (one BRAF and the other WNK2). Two patients who relapsed after sustained CR had major branching evolution where a previously undetectable focal deletion of PMAIP1 (NOXA) was seen at PD. Importantly, one of these deletions was a biallelic event. Venetoclax sensitivity assays conducted on PMAIP1 knockout in the MM t(11;14) cell line, KMS12PE, demonstrated significantly reduced cell death across all drug concentrations (p<0.05), validating the loss of NOXA as a mechanism of resistance to Venetoclax in MM. Finally, similarly with what was previously reported in chronic lymphocyte leukemia treated with Venetoclax (e.g., Herling et al Nat Comm 2018), CDKN2A/B monoallelic and biallelic focal deletions were selected post-Venetoclax, at PD in 4 patients while TP53 SNV/deletions were selected from subclonal to clonal in 2 patients at PD. Conclusion: In this study, we demonstrate that mutations involving the MAPK pathway identify a population of MM patients with t(11;14)(CCND1;IGH) who are unlikely to respond to Venetoclax. We also show that genomic events involving the MAPK and BCL2/MCL1 pathways are primarily responsible for disease progression after initial response. These findings highlight the critical role of comprehensive genomic profiling through WGS in identifying mechanisms of resistance to targeted therapies in MM, aiding patient selection for Venetoclax, and guiding the development of novel drug combinations.

Introduction: Despite the success of anti-CD19 Chimeric Antigen Receptor T cells (CART19) in patients with B-cell acute lymphoblastic leukemia (B-ALL), an allogeneic haematopoietic stem cell transplantation (HSCT) might rescue patients with disease recurrence. However, in patients at high risk of relapse, indication and timing of HSCT are challenging. Whether waiting for detectable disease or proceeding to consolidative HSCT in remission, is still controversial. This GoCART Coalition registry study aimed at investigating the outcome of patients who received HSCT after CART19. Methods: We retrieved data from the EBMT registry on adults and children with B-ALL who received autologous CART19 from 2016 and 2023. Baseline, previous treatment, bridging therapy, CART19 therapy, B cell aplasia duration, outcome, disease status at follow-up were collected. Kaplan Meier estimates were used for overall survival (OS), leukemia-free survival (LFS) and non-relapse mortality (NRM) from date of HSCT, whereas cumulative incidence was used for relapse after HSCT. The relapse was defined as molecular or hematologic recurrence of the disease. Relapse and NRM were mutually competing events. Results: Of 345 patients (173 adults and 172 children) infused with CART19 (Tisagenlecleucel in 65.2%, Varnimcabtagene autoleucel 25.8%, brexucabtagene autoleucel 5.5%, and others 3.5%), 113 subsequently received an HSCT (37 adults and 76 children; median age 13.5 years, IQR 8.2-22.2) at a median of 6.2 months (3.7-11.8) after CART19 infusion. Median follow-up was 1.6 years (95%CI 1.1-1.9). Overall, 67/113 (59.3%) patients were transplant-naive (17 adults; 50 children). 78.2% received a myeloablative conditioning, 36.8% were grafted from a mismatched related donor. Most of the patients (64.2%) were transplanted in CR3 or more. Disease status at HSCT was relapsed disease for 9% of the patients, whereas among patients in CR with reported MRD 26/95 (27%) received HSCT with MRD positivity (MRD+). Among the patients with disease recurrence after CART19, 19/60 (32%) detected a CD19-negative clone. Indication for the subsequent HSCT was reported for 110 patients, as follow: (I) Rescue HSCT in 68 (62%) patients with molecular/morphological disease after CAR-T (including one patient with MDS post CAR-T); (II) Pre-emptive HSCT in 22 (20%) patients with B-cell aplasia loss with no signs of disease recurrence; (III) ConsolidativeHSCT in the 20 patients (18%) who were transplanted for the high risk of relapse, despite ongoing B cell aplasia and no disease recurrence. Median time elapsed between CART19 and HSCT was 9.5, 4.4 and 3.4 months in the three groups, respectively. The 2-yr OS was 71.1% (95%CI 59.8-79.7) and 2-yr LFS was 53.5% (41.9- 63.8), relapse incidence was 32.7% (22.4-43.5), while NRM was 11.6% (6.1-19.1). The 2-years LFS was 59.6% (45.2-71.4) vs 42% (19.2-63.4), for patients transplanted with negative or positive MRD, respectively. 5/11 patients transplanted with overt disease (including one with MDS) relapsed or died, the 6 survivors free of disease had follow-up inferior to 2 years. Children compared with adults showed better OS (76.8%, 62.1-86.4; 59.9%; 40.8-74.6; p=0.02), and better LFS (64.3%, vs. 36.4%; p= 0.02). Patients receiving a rescue HSCT for MRD+ or overt relapse had a significant lower LFS (43.6% and 33.2%), as compared to pre-emptive (77.3%) and consolidative HSCT (83.6%, p= 0.001). In univariate analysis, no significant differences in OS (74.5% vs 65.6%, p=0.32), LFS (54.3% vs 52.4%, p=0.75) and NRM (10.7% vs 12.9%, p=0.68) were reported for those patients having a previous HSCT before CART19. Conclusion: To the best of our knowledge this is the largest cohort of transplanted patients after CART19. In this “real-world” registry-based study we found that patients transplanted without disease recurrence had a better LFS, also accounting for MRD. For those who experienced molecular or overt relapse, achieving MRD negativity appeared to be relevant for a better outcome. The low NRM, with no differences between pre-transplanted and transplant naive patients, suggest that HSCT after CART19 is well tolerated, and represent a valid strategy to reduce the risk of relapse. As it remains unclear for which patients autologous CART19 cells remains a stand-alone treatment, future studies should focus on strategies for early identification of patients at higher risk of treatment failure.

Background: Multiple myeloma (MM) is an incurable plasma cell malignancy with several recurrent primary cytogenetic abnormalities including t(11,14)(q13;q32), resulting in increased expression of CCND1. Although 40% of patients with t(11;14) MM respond favorably to the BCL-2 inhibitor venetoclax (ven), 60% fail to achieve an objective response. Previous studies have suggested upregulation of PMAIP1, encoding the pro-apoptotic NOXA protein, in association with ven sensitivity (Leblay, Blood, 2024). Here we sought to evaluate the role for NOXA in ven response in t(11;14) MM. Methods: We analyzed whole exome, whole genome and RNA sequencing data of CD138+ tumor cells from 1,359 patients with MM in the CoMMpass and Mayo Clinic cohorts. The histone mark H3K27ac was assessed in t(11;14)+ KMS12PE and U266B1 human myeloma cell lines using ChIP-seq. Gene expression and protein levels of PMAIP1 (NOXA) were also detected by qRT-PCR and Western blot, respectively. Live cell detection was evaluated by Annexin V and PI using flow cytometry and by YoYo3 dye using IncuCyte following treatment with ven. Results: The t(11;14) MM subtype was associated with a 1.6-5.5-fold increased expression of PMAIP1 compared to non-t(11,14) MM in the CoMMpass and Mayo Clinic cohorts (p<0.0001). These findings are consistent with a significant correlation between CCND1 and PMAIP1 expression in both cohorts (p<0.001). To evaluate whether cyclin D1 is directly associated with increasing expression of PMAIP1 in t(11;14) MM, we generated a cyclin D1 knock out (KO) version of the U266B1 line using CRISPR/cas9. Two independent U266B1 KO cell lines showed reduced expression of PMAIP1 and NOXA protein compared to the WT U266B1 consistent with a role for cyclin D1 in regulating PMAIP1 expression. In addition, the KO lines had a 4.8-fold reduced H3K27ac signal at the PMAIP1 locus in comparison to the WT control suggesting a role for cyclin D1 in promoting H3K27ac. We previously observed increased expression of CCND1 in association with the G allele compared to the A allele of rs9344 in both the CoMMpass and Mayo Clinic cohorts (Leukemia, in press). We next asked whether the G risk allele of rs9344 within CCND1 impacted gene expression and H3k27ac levels at the PMAIP1 locus. To study the allele specific effect of CCND1, we used the CRISPR/cas9 edited KMS12PE WT (rs9344 AA) and Knock In (KI) (rs9344 GG) cell lines. In the KI cells, the G allele was accompanied by an ~2-fold increased expression of PMAIP1 and NOXA protein detected by western blot (<0.05). Increased PMAIP1 expression in KI lines was also accompanied by a 2.2-fold increased H3K27ac further suggesting a role for the G allele of rs9344 in promoting H3K27ac and gene expression at the PMAIP1 locus. Finally, we evaluated the consequence of PMAIP1 expression levels in relation to ven response. Increased expression of PMAIP1 and elevated levels of NOXA protein in the KMS12PE KI lines was associated with increased sensitivity to ven resulting in ~50% increase in cell death of KI vs. WT lines (p<0.02). Conclusion: We demonstrate a role for cyclin D1 in regulating PMAIP1 expression through H3K27ac resulting in increased NOXA protein. Levels of NOXA are associated with the G allele of rs9344 and increased venetoclax response.

Background: Acute limb ischemia (ALI) requires prompt revascularization to preserve the extremity and minimize the effects of systemic reperfusion. Once ALI is recognized, delays in revascularization are generally due to system issues (e.g., transfer) and there is a need for a method of temporary extremity perfusion to reduce warm ischemic time. Lower Extremity Extracorporeal Distal Revascularization (LEEDR) is a percutaneous technique that uses a pump and circuit to deliver oxygenated blood into a pedal artery. Hypothesis: Extracorporeal perfusion can improve survival from ALI. Aims: The aim of this study is to use a swine model of prolonged hindlimb ischemia to compare survival and functional outcomes of LEEDR versus control (warm ischemia). Methods: Anesthetized female Yorkshire swine (40-60kg) underwent hindlimb ischemia using endovascular balloon occlusion and were randomized to control (n=6) or LEEDR (n=6). Controls underwent 9 hours of ischemia. LEEDR animals underwent contralateral femoral and ipsilateral posterior tibial artery cannulation followed by 8 hours of extracorporeal perfusion into the ischemic limb. Subjects were revascularized by removing the endovascular balloons, restoring extremity blood flow, and undergoing a 4-hour critical care period before extubation and observation for 48 hours. Primary outcome was survival and secondary outcomes included functional extremity scores (Tarlov Gait Score), compartment pressures (mmHg) and biochemical markers of reperfusion. Results: Survival was higher in animals undergoing LEEDR (83% vs. 0%; p=0.001), with most control animals succumbing to acute lung injury. LEEDR animals had a higher functional gait score (5.9±0.3 vs. 2.5±0.7; p<0.001) and lower compartment pressure (8±2 vs. 28±4; p=0.002) compared to controls. Biochemically, the LEEDR group had lower potassium (4.5±0.3 vs. 5.3±0.4; p=0.001) and lactate (1.2±0.5 vs. 2.0±0.7; p<0.001) measurements compared to controls during reperfusion and recovery. Conclusion: LEEDR can effectively mitigate 8 hours of extremity ischemia in a swine model, reducing mortality from reperfusion, while improving functional gait score and eliminating compartment syndrome. This percutaneous approach to ALI opens a new field of extracorporeal limb salvage, which can temporize extremity perfusion improving outcomes in patients who have traditionally had limited options due to prolonged warm ischemia.