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Key Points The kidney microvasculature was quantified reliably in human autosomal dominant polycystic kidney disease early on, using super-resolution ultrasound localization microscopy. Microvascular parameters correlated with structural and functional indices, constituting promising biomarkers to evaluate noncystic parenchyma. Microvascular parameters may serve to assess disease severity and monitor progression from the early stages of the disease. Background In vitro studies in individuals with autosomal dominant polycystic kidney disease (ADPKD) have shown extensive intrarenal microvascular remodeling. However, analyses have been limited to the time of kidney failure because of the invasive nature of current methodologies to assess the intrarenal microvasculature. We hypothesized that super-resolution ultrasound microvascular imaging, known as ultrasound localization microscopy, enabled by high-framerate ultrasound imaging and microbubble localization and tracking postprocessing techniques, would safely, reliably, and reproducibly assess the intrarenal microvasculature in individuals with ADPKD at an early stage of the disease. Methods We prospectively enrolled young (<40 years of age), well-characterized, early-stage (eGFR >90 ml/min per 1.73 m 2 ) individuals with ADPKD, and sex–age 1:1 matched controls ( n =17 each) and assessed the intrarenal microvasculature using ultrasound localization microscopy. We determined the intersonographer reliability, intraobserver repeatability, and interobserver reproducibility of microvascular parameters in both groups, and the day-to-day variability in the control group. Microvascular parameters were correlated with structural (total kidney volume) and functional (eGFR) markers in individuals with ADPKD. Results Ultrasound localization microscopy provided a super-resolved map of the intrarenal microvasculature in ADPKD and matched controls. Intrarenal microvascular parameters ( e.g ., vessel density) were quantified in a safe, reliable (intraclass correlation coefficients, 0.96; 95% confidence interval, 0.91 to 0.98), reproducible (intraclass correlation coefficient, 0.96; 95% confidence interval, 0.93 to 0.98), and repeatable (coefficient of variations, 3.6%) manner. In control individuals, the day-to-day variability of most parameters was low, with coefficient of variation ranging from 1.8% to 10.7%. Microvascular parameters differed in individuals with ADPKD compared with controls, despite preserved eGFR. Interestingly, cortical vessel density and its derived perfusion correlated directly with eGFR, whereas tortuosity indices presented an inverse correlation. Conclusions Ultrasound localization microscopy provided a safe and reliable in vivo assessment of the human intrarenal microvasculature.

Abstract Introduction: First-line therapy for mantle cell lymphoma (MCL) represents a critical opportunity for clinical benefit via sustained complete response. Multitargeted combinations, including optimized chemotherapy with novel agents targeted to MCL, may best address the biologic heterogeneity of this disease. Building on prior experience using modified VR-CAP and R-cytarabine, we enhanced this regimen by adding acalabrutinib while reducing cytarabine, aiming for improved efficacy and safety without impeding stem cell collection. To evaluate this regimen, we conducted a phase 2 multicenter trial at four centers in the Academic and Community Cancer Research United (ACCRU) network. Methods: CARiBOU (ACCRU-LY-1804) employs alternating VR-CAP and R-cytarabine with continuous acalabrutinib, in six 21-day cycles, for previously untreated MCL. Eligible patients (pts) were at least 18 years old with adequate organ function, measurable disease, no CNS involvement; and were ASCT-eligible per investigator. VR-CAP (cycles 1, 3, and 5) employed bortezomib 1.3 mg/m² subcutaneously days 1,8, and 15; rituximab 375 mg/m² day 1; cyclophosphamide 750 mg/m² day 1; doxorubicin 50 mg/m2 day 1; and prednisone 100 mg PO days 1-5. Cycles 2,4, and 6 used outpatient rituximab with cytarabine at 3 g/m² x 2 daily doses in the first 5 pts, after which the dose was reduced to 2 gm/m2 x 2 daily doses due to thrombocytopenia. Acalabrutinib 100 mg p.o. twice daily was given continuously but held for grade 4 thrombocytopenia or clinically significant toxicity. Growth factors and prophylactic antimicrobials were required. Responses were assessed after six cycles using FDG PET/CT, bone marrow aspirate/biopsy (BM Bx), and endoscopy when indicated (Lugano 2014). The primary endpoint was complete metabolic response (CMR) rate at end of treatment (EOT). Secondary endpoints included safety, feasibility of stem cell collection, proportion proceeding to ASCT, and progression-free (PFS) and overall survival (OS). Peripheral blood measurable residual disease (MRD) was evaluated using the ClonoSEQ assay (Adaptive Biotechnologies). A Simon two-stage design was used, targeting a CMR rate ≥ 70% versus a null rate of 50%, with a total sample size of 39 evaluable pts. Results: 41 pts were accrued from October 2021 through May 2025, 37 of whom completed all 6 cycles and are evaluable for response; two are still on therapy, and two discontinued therapy early for toxicity. Median age was 63 years (range 41-73), 22% were female, and 85% were White. MIPI risk groups were low (44%), intermediate (39%), and high (17%), and Ki-67 was ≥ 30% in 54% of pts. Three pts (7%) had known TP53 mutations by sequencing. At EOT, the CMR rate was 85.3% among all pts (35/41; 95% CI 67.9%-92.9%), or 94.5% among evaluable pts (35/37). BM Bx was performed in 31 pts at EOT, 30 of which (96.8%) were negative for MCL. Undetectable peripheral blood MRD using a 10^6 threshold (uMRD6) was achieved at EOT in 78.1% (25/32) of tested pts, and 93.8% (30/32) achieved uMRD5. Nine of 41 pts underwent ASCT; no patient failed stem cell collection. Maintenance therapy was not protocol-defined but included rituximab in 91.9% of pts and a BTK inhibitor in 21.6% of pts. With a median follow-up of 16.7 months, PFS and OS rates at 18 months were 76.7% (95% CI: 60.7%-96.9%) and 95.5% (95% CI: 87.1%-100%). Toxicities were primarily hematologic. Grade 3+ toxicities included thrombocytopenia (66.6%), neutropenia (28.2%), and anemia (25.6%). Grade 3+ febrile neutropenia was observed in 10.2% of pts. Peripheral neuropathy was seen in 20.5% of pts and all grade 1-2. Bleeding events included purpura in 2 pts (5.2%) and epistaxis in 1 patient (2.6%). One case of atrial fibrillation was observed. Eighteen pts required temporary dose hold of acalabrutinib for toxicity (mainly thrombocytopenia), and 2 had acalabrutinib dose reductions. Serious adverse events occurred in 6 pts, and no treatment-related deaths occurred. Conclusions: CARiBOU is an efficient, highly effective outpatient regimen for 1st line MCL, employing intermediate dose cytarabine with continuous acalabrutinib. With supportive care and platelet monitoring, this approach safely yielded high rates of CMR and uMRD6, supporting multitargeted induction therapy for appropriate pts with untreated MCL.

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

Abstract Introduction: Lisocabtagene maraleucel (liso-cel) was approved in the United States for the treatment of CLL in 3/2024 for patients who have received two prior lines of therapy including a covalent BTK inhibitor and a BCL-2 inhibitor. Data regarding outcomes of liso-cel is limited to reports from the registrational TRANSCEND-CLL 004 clinical trial which had strict inclusion and exclusion criteria. This work investigates the real-world efficacy and safety of liso-cel for patients with CLL and its efficacy in specific sub-populations. Methods: This is a multi-institutional retrospective study (Collaborative Assessment of Real-World Evidence of Lisocabtagene Maraleucel in Patients with Relapsed/Refractory CLL/SLL [CARE CAR-T CLL]) of patients with CLL who received commercial liso-cel in the United States. Patients with Richter transformation were excluded. Response was defined by iwCLL criteria. Patients who did not undergo a marrow biopsy but met other criteria for a complete response (CR) were categorized as unconfirmed CR (CRu). CRS and ICANS were graded per ASTCT criteria. Results: A total of 30 patients were identified with a median age of 67 years (range 44 – 80). Twenty of thirty patients (67%) had either del17p and/or mutated TP53, and 8/30 (27%) had complex karyotype (≥ 3 abnormalities) at time of liso-cel infusion. Patients received a median of 6 prior lines of therapy (range 1 - 12), and 24 (80%) were previously treated with chemotherapy. All patients had previous exposure to a covalent BTK inhibitor and a BCL-2 inhibitor. Twenty-seven (90%) of patients had prior exposure to pirtobrutinib. Twenty-nine patients (96.7%) received bridging treatment that was stopped after leukapheresis with 1 patient in CR and 25 patients in PR at time of liso-cel. Eighteen patients (60%) were treated with pirtobrutinib as the last line of treatment prior to liso-cel. Median length of time on pirtobrutinib prior to liso-cel infusion was 4 months (interquartile range [IQR], 2 – 8 months). Twelve (66.7%) patients stopped pirtobrutinib between leukapheresis and lymphodepletion, and 6 continued after liso-cel. Best CR/CRu rate was 60.0% (CR, n = 17/30; CRu, n = 1/30), and best overall response rate (ORR) was 83.3% (25/30) with median time to best response of 30 days (IQR, 28 – 30 days). Of the 18 patients who received pirtobrutinib as their last line of therapy, 13 (72%) achieved a CR/CRu. Meanwhile, of the 12 patients who did not receive pirtobrutinib as their last line of therapy, only 5 (28%) achieved a CR. Measurable residual disease testing (MRD) by flow cytometry was done in 14/30 patients, and 9 patients (64%) had achieved undetectable MRD (uMRD). MRD by next generation sequencing (NGS) was done in 17 patients, and 7 (41%) patients had uMRD. Twenty-seven of 30 patients (90%) were alive at time of data collection. Median follow-up was 3.3 months (IQR, 1.2 – 8.9 months). Twenty-six patients (87%) experienced any grade cytokine release syndrome (CRS), and 3 patients experienced grade 3 CRS (10%). Twelve patients (40%) experienced any grade immune effector cell-associated neurotoxicity syndrome (ICANS), and 4 patients (13%) experienced grade 3 ICANS. There were no grade 4 or 5 CRS or ICANS. One patient experienced grade 3 immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome (IEC-HS). At day 30, patients had a median absolute neutrophil count of 1.7K/μL (IQR, 0.8 – 3.6K/μL), hemoglobin of 11.7 g/dL (IQR, 8.6 – 13.1 g/dL), and platelet count of 72K/μL (IQR, 29 – 119K/μL). Conclusion: Real-world analysis of liso-cel for patients with relapsed/refractory CLL showed CR and ORR of 60.0% and 83.3%, respectively. Despite having a heavily pre-treated and chemotherapy-exposed population and with over half the patients having high-risk features, these response rates are higher than what was described in the TRANSCEND-CLL 004 clinical trial. These results are limited by the short follow-up period and the variability in response assessment typical of a retrospective study. As we increase our sample size, we will also be interested if the use of the non-covalent BTK inhibitor pirtobrutinib prior to liso-cel is associated with a higher CR rate, mimicking the findings of the sub-cohort analysis of TRANSCEND-CLL 004 where the concurrent use of ibrutinib led to higher CR rates. Further updates and patients from additional collaborators will be presented at the meeting.

Abstract Introduction Obecabtagene autoleucel (obe-cel) and brexucabtagene autoleucel (brexu-cel) are CD19 targeted chimeric antigen receptor T cell (CAR-T) therapies, approved for the treatment of adults with relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (ALL). Mechanistic differences between obe-cel and brexu-cel including differing costimulatory domains (4-1BB vs. CD28), CD19 binding domains (intermediate vs. high affinity) and split dose (Days 1 and 10) vs. single infusion may impact in-vivo cellular kinetics that translate into variant clinical outcomes. In pivotal trials, obe-cel resulted in lower rates of severe cytokine release syndrome (CRS) and immune effector cell associated neurotoxicity syndrome (ICANS) compared to brexu-cel with comparable efficacy (Roddie et al., NEJM 2025; Shah et al., Lancet 2021). Real-world utilization and outcomes with obe-cel are unknown given the relatively recent approval. Methods The ROCCA database, comprising real world data from patients (pts) with r/r ALL treated at 40 North American institutions was utilized in this analysis. Pts with r/r ALL were eligible if they were apheresed for obe-cel since its approval (11/8/2024) or brexu-cel over a comparable period (since 8/1/24) and had at least 30 days of follow up. Data cut off was 7/15/2025. CRS/ICANS were graded per ASTCT criteria. Measurable residual disease (MRD) was assessed by flow cytometry and/or next generation sequencing per institutional standards. Results 38 pts have undergone apheresis for obe-cel (36 infused, all received both infusions) and 54 (53 infused) for brexu-cel over the study period. Pts in the obe-cel and brexu-cel cohorts had the following baseline characteristics: median age, 47 vs. 39 years; ECOG 2+, 15% vs. 26%; Ph+ disease, 24% vs 13%; KMT2Ar, 0 vs. 4%; TP53m, 11% vs 11%, and hypodiploid karyotype, 5% vs 6%. The following prior treatment patterns were observed: median lines of therapy before CAR-T 3 vs. 3; prior SCT 24% vs. 30%, prior blinatumomab 68% vs. 46%, prior inotuzumab 45% vs. 30%. At apheresis, active disease (&gt;5% bone marrow blasts) was present in 47% vs. 55% of obe-cel and brexu-cel pts, respectively; the remainder were in CR (with 18% vs. 22% in MRD- CR, respectively). Among obe-cel (n= 35 [92% of cohort]) and brexu-cel (21 [38% of cohort] pts with disease re-assessment prior to lymphodepletion (LD), 31% vs. 43% had active BM disease, respectively; few pts (24% vs. 17%) had &gt;20% marrow disease burden prior to LD. CAR-mediated toxicity differed significantly between the cohorts. CRS occurred in 56% of obe-cel pts compared to 94% of brexu-cel pts (p &lt; 0.0001). There were no Gr3+ CRS events among the obe-cel pts; 3 (6%) brexu-cel pts had Gr3+ CRS (p = 0.27). ICANS occurred in 17% of obe-cel pts vs. 51% of brexu-cel pts (p = 0.001). Gr3+ ICANS occurred in 6% of obe-cel vs. 32% of brexu-cel pts (p = 0.0027). Among the obe-cel pts, CRS occurred in 31% after the first infusion and 46% after the second; ICANS occurred in 3% after the first infusion and 15% after the second. Prolonged Gr4 neutropenia (ANC &lt; 500 cells/uL beyond day 30 from infusion) occurred in 24% of obe-cel vs. 28% of brexu-cel pts (p = 0.73). Deaths within the first 28 days of infusion occurred in 0 obe-cel pts and 4 brexu-cel pts (2 of infection, 1 of infection/brain bleed, and 1 of liver failure in the setting of Gr4 CRS and HLH). Response rates were high and did not significantly differ between cohorts (p = 0.85). Among the 31 obe-cel pts with available response data, 25 (81%) achieved an MRD- CR/CRi, 3 (10%) had an MRD+ CR/CRi, 2 (6%) had a CR/CRi with unknown MRD, and 1 (3%) did not respond. Among 41 brexu-cel pts with available response data, 33 (80%) had an MRD- CR/CRi, 4 (10%) an MRD+ CR/CRi, and 4 (10%) CR/CRi with unknown MRD. Conclusion Pts selected for obe-cel apheresis were similar to those for brexu-cel over the study period (noting that not all centers had access to obe-cel during this time). Similar to clinical trial results, obe-cel was associated with lower rates of CRS/ICANS. Rates of MRD-negative CR were high and did not differ between cohorts. A larger sample and longer follow up are required for further analyses; we anticipate a cohort of ~75 obe-cel treated pts by the annual meeting and will provide updated data.

Abstract Background Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is the most common leukemia in US adults and incidence increases with age. Although the treatment (tx) landscape has evolved, it is unclear whether tx selection differs for older patients (pts), given concerns around comorbidities, toxicity, and efficacy. There is a need to better understand pt characteristics, tx patterns, and biomarker use among pts aged ≥65 yrs with CLL/SLL in the current therapeutic era. Methods A retrospective longitudinal study was conducted using the de-identified 100% Medicare Fee-for-Service (FFS) Research Identifiable Files. Included pts were diagnosed with CLL/SLL at age ≥65 and initiated first-line (1L) tx 1/1/2020-9/30/2024 (with ≥12 mo in database prior to 1L tx start). Index date was defined as date of 1L tx start, and pts were followed to death, end of Medicare enrollment, or study end, whichever occurred first. 1L tx was defined as any CLL pharmacologic tx within the first 90 days of index date. Tx utilization was summarized as the number and proportion of pts who received each tx at each line. Descriptive statistics were used to summarize demographic and social characteristics and baseline comorbidities, in all pts and by 1L tx. Proportion and timing of documented biomarker orders any time prior to index were summarized by test type (CLL fluorescence in situ hybridization [FISH], TP53 DNA sequencing and immunoglobulin heavy chain variable region [IGHV] test) and by 1L tx. Results Of the 21,008 pts included, median age was 76.4 yrs at 1L tx, with 43% of pts aged 65-74 yrs, 43% aged 75-84 and 14% aged ≥85. The majority of pts were male (58%) and White (91%). About 8% and 9% of pts had dual eligibility status and low-income subsidy, respectively. Median Charlson Comorbidity Index (CCI) was 4 (range: 1-21), with 40% of pts having CCI ≥5. Covalent Bruton tyrosine kinase inhibitor (cBTKi) monotherapies (mono) were most common at 1L tx (41%), including 10% zanubrutinib (zanu), 15% ibrutinib (ibr), and 16% acalabrutinib (acala). B-cell lymphoma 2 (BCL2)+anti-CD20 monoclonal antibody (mAb) was less common (11%), and chemoimmunotherapy (CIT) was used by 13% of pts, mostly BR (8%) and FCR (3%). Other less common tx included cBTKi+anti-CD20mAb (6%) or cBTKi+BCL2 therapies (1%). Among remaining pts, most received anti-CD20mAb (22%). The use of cBTKi mono increased from 41.7% in 2020 (ibr 30.6%; acala 11.1%) to 47.6% in 2024, driven by increased use of zanu (27.8%; acala 15.7%; ibr 4.2%). BCL2+anti-CD20mAb increased from 9.2% in 2020 to 12.6% in 2024. Pts treated with cBTKi mono were older than those with BCL2+anti-CD20mAb (median age 77.2 vs 74.5), and more likely to have dual eligibility status (10% vs 4%) or low-income subsidy (11% vs 5%). More pts who received zanu mono had CCI ≥5 (39%) versus acala (36%), ibr (35%), or BCL2+anti-CD20mAb (32%). Pts with BCL2+anti-CD20mAb were less likely to have diabetes (23% vs 26%), congestive heart failure (CHF; 16% vs 19%), chronic pulmonary disease (23% vs 27%), and renal diseases (23% vs 27%). Pts with ibr were less likely to have myocardial infarction (29% vs 34%), coronary artery disease (22% vs 25%), CHF (16% vs 19%), and atrial fibrillation (12% vs 18%). Overall, 69% of pts had FISH testing prior to 1L tx, but test orders for TP53 (12%) or IGHV (28%) status were infrequent. Pts with ibr had the lowest rates of TP53 tests (6%), whereas pts with CIT had the lowest rates of IGHV tests (16%). The timing of tests showed a binomial distribution where most pts received FISH, TP53, or IGHV tests either ≤60 days prior to 1L tx (46%, 50%, 33%), or &gt;1 yr before 1L tx (30%, 22%, 43%). Among pts who received ≥2 lines of therapy for CLL (n=4428; 21%), cBTKi mono was the most common in 2L (41%), including 14% zanu, 17% acala, and 10% ibr. CIT and BCL2+anti-CD20mAb were used in 12% and 9% of pts, respectively. Only 634 (3%) pts had 3L+ tx, of whom 33% received cBTKi mono, including 16% zanu, 12% acala, and 5% ibr (5%). Conclusion This large real-world study found that cBTKi mono was the most common 1L tx choice among pts aged ≥65 with CLL/SLL, with increased use of next-generation cBTKi. Pts with more baseline comorbidities were less likely to receive ibr or BCL2-based tx. FISH testing was not performed in nearly one-third of pts, and most pts did not have TP53 or IGVH sequencing prior to tx. Future studies are needed to continue to evaluate evolving tx paradigms in older pts with CLL/SLL.

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

Abstract BACKGROUND: DNA methyltransferase inhibition offers palliative benefit but does not alter disease biology. in chronic myelomonocytic leukemia (CMML, Merlevede J et al. Nat Comm 2016). This was conclusively demonstrated in the phase 3 DACOTA study, where decitabine did not improve event-free survival in comparison to hydroxyurea (median 12.1 versus 10.3 months, P=0.27) in advanced myeloproliferative CMML (MP-CMML). Hence, there is in urgent need to develop disease modifying therapies for this dismal condition. We and others have demonstrated a role for RAS mutations in MP-CMML through the activation of the KMT2A-PLK1 axis. Targeting of this axis using onvansertib, an inhibitor of PLK1, has demonstrated its pre-clinical efficacy in MP-CMML patient-derived organoid and xenograft models. (Carr RM et al. Nat Comm 2021). METHODS: We conducted a single center phase 1 study to assess the safety and efficacy of onvansertib in relapsed/refractory MP-CMML (NCT05549661). We used a Bayesian Optimal Interval (BOIN) study design to determine the maximum tolerated dose (MTD). The three dose cohorts included 6, 9 and 12 mg/m2 given orally from days 1 to 21 of each 28-day cycle. Key inclusion criteria included a WHO-defined diagnosis of MP-CMML with a white blood cell (WBC) count &gt; 13,000/mm3 and adequate organ function (estimated GFR &gt; 50 mL/min/m2). Response was evaluated per the MDS/MPN International Working Group Criteria (Savona et al. Blood 2015). Targeting efficacy was assessed by measuring phosphorylation of TCTP (a PLK1 substrate), specifically pTCTP/TCTP ratios by immunoblotting in peripheral blood mononuclear cell (PBMC) samples pre and post cycle 1 (Days 1, 7, 21) and end of cycle 3. Pharmacokinetic studies and translational correlative studies were conducted per protocol. RESULTS: Between April 2023 and July 2025, a total of 9 patients were enrolled. The median age at enrollment was 68 years (range: 60-83); all caucasian with 4 (44%) males. All patients had a diagnosis of CMML-1 with a median bone marrow (BM) blast percentage of 4 (0-9), median hemoglobin 10 (7.1-13.2) g/dL, median WBC count of 11.1 (3.1-72.7) x 109/L (4 patients had a WBC count &lt; 13 x 109/L at enrollment due to hydroxyurea use but were confirmed to be MP-CMML at diagnosis), absolute monocyte count 2.1 (1.9-19.6) x 109/L, and platelet count of 36 (20-494) x 109/L. TET2 (89%), SRSF2 (78%), ASXL1 (56%), NRAS, KRAS and CBL (22% each) were the most frequent molecular abnormalities. Previous therapies included hydroxyurea (n=8) and decitabine (n=1). Four patients were enrolled at the 6mg/m2dose level, 2 at the 9 mg/m2 dose level and we currently have one patient at the 12 mg/m2 dose level. While there were 2 planned patients at the 6 mg/m2 dose level, due to a case of pericardial effusion that was possibly drug related, an additional two patients were enrolled at the same dose level, without any dose limiting toxicity (DLT). Targeting efficacy was confirmed by pTCTP immunoblotting in PBMC samples from 4 patients (6 and 9 mg/m2 dose levels) showing suppressed pTCTP/TCTP ratios. No confirmed DLT has been identified thus far, and no grade 3 or 4 toxicities attributable to the study drug have been reported. Possible or unrelated grade 3 adverse effects included infections (sepsis/cellulitis, n=2, 22%), acute kidney injury (n=1, 11%), pericardial effusion (n=1, 11%), and atrial fibrillation with rapid ventricular response (n=1, 11%). Median duration on therapy was 124 (range: 15-654) days with most common cause of study discontinuation being disease progression (33%). Response was assessed as per the MDS/MPN IWG criteria in patients who received at least 1 cycle (n=8) with 3 (38%) patients meeting criteria for either hematological or optimal marrow response. Specifically, there was one (14%) patient with &gt;100% platelet response, one (14%) with normalization of WBC count (baseline WBC count &gt;50 x 109/L), one (14%) optimal marrow response with BM blast% reduction from 8 to 2, facilitating candidacy for an allogeneic hematopoietic stem cell transplantation, and three patients (38%) remained as stable disease. CONCLUSION: In MP-CMML, PLK1 inhibition with onvansertib is relatively well tolerated and shows preliminary efficacy in approximately 40% of patients, with one patient having an optimal marrow response at the 9 mg/m2 dose. Future directions include a dose expansion phase and studying upfront combination with DNA methyltransferase inhibitors.

Abstract Introduction: Brexucabtagene autoleucel (Brexu-cel) is a CD19-targeted chimeric antigen receptor (CAR-)T cell therapy approved for treatment of relapsed/refractory (r/r) B-ALL. Brexu-cel's approval was founded on data from the ZUMA-3 trial, in which 78 patients (pts) were treated at the pivotal dose of 1x10e6 CAR-T cells/kg, resulting in a complete remission (CR) rate of 73%. Three-year follow-up from ZUMA-3 demonstrated median relapse-free and overall survival (RFS/OS) of 11.6 and 25.6 months (mos) for all treated pts. Amongst responders, the median OS was 60.4 mos for those who did not receive a subsequent allogeneic hematopoietic cell transplant (HCT) (n=43), but only 36.3 months for those who did (n=14). This has led some to conclude that HCT may not be beneficial following brexu-cel therapy for r/r B-ALL; however, it must be noted that 29 (37%) of the pts treated on ZUMA-3 received brexu-cel for post-HCT relapse. T cells collected from individuals who relapse in the post-HCT setting are largely of donor origin, making the CAR-T product comparable to a genetically modified donor lymphocyte infusion (DLI). The immunology at play in this scenario may be different from that in which CAR-T cells are of truly autologous origin. Methods: The Real-World Outcomes Collaborative for CAR-T in ALL (ROCCA) consortium database includes pt characteristics and outcomes of brexu-cel therapy given as standard-of-care across 41 US institutions. We identified pts who achieved an MRD negative (neg) CR by either flow cytometry (minimum sensitivity 10e-4) or NGS following brexu-cel for r/r Ph neg B-ALL and categorized them into three groups with regard to use of HCT: Never HCT, Pre-CAR HCT, or Post-CAR HCT. Pts who received second HCT following brexu-cel for post-HCT relapse (n=9) were excluded. Pt/disease characteristics, RFS, and OS were assessed for each group, landmarked at 73 days after brexu-cel infusion (the median time to consolidative allogeneic HCT). Results: In the ROCCA database we identified 165 pts who achieved MRD neg CR following brexu-cel, amongst whom 69 never underwent HCT, 49 were transplanted pre-CAR (ie, brexu-cel served as a genetically modified DLI), and 47 underwent post-CAR consolidative HCT while in CR. The median follow-up is 373 days. The median age was higher in the Never HCT group (49, range 19-83) in comparison with the Pre-CAR HCT (40, 24-72) and Post-CAR HCT (34, 18-70) groups. Thirty-five percent were &gt;60yo in the Never HCT group vs 20% in the Pre-CAR HCT and 9% in the Post-CAR HCT groups. Ph-like disease was present in 38%, 29%, and 43% of the Never HCT, Pre-CAR HCT, and Post-CAR HCT groups, respectively (p=0.35). No significant differences were observed in pre-apheresis bone marrow blasts, presence of CNS disease at apheresis, prior blinatumomab or inotuzumab treatment, or use of bridging therapy across the groups, though there was a higher prevalence of non-CNS extramedullary disease in the Pre- and Post-CAR HCT groups (32, 39%) vs the Never HCT group (13%) (p=0.004). A minority of pts in all groups were deemed to be in MRD neg CR prior to apheresis (6-20%). Median RFS was 260 days in the Never HCT group and not reached in the Pre- and Post-CAR HCT groups (p=0.002), with respective 1-yr RFS of 38%, 64%, and 67%. Median OS was not reached in any group and was similar for all at 1-yr at 68-79% (p=0.13). Characteristics of those in the Never HCT group who were least likely to relapse included age &gt;60 (OR 0.22, CI 0.07-0.73 vs age 18-39, p=0.024) and those with non-Ph-like B-ALL (OR 0.33, CI 0.12-0.94, vs Ph-like, p=0.037) in univariate analyses. Conclusions: Real-world data regarding outcomes following brexu-cel therapy allow evaluation of the role for consolidative allogeneic HCT, which remains one of the most important unresolved questions in the use of CAR-T therapy for r/r B-ALL. This analysis demonstrates that a first consolidative HCT after achieving MRD neg CR with brexu-cel is associated with a significant decrease in relapse. Additionally, use of brexu-cel for post-HCT relapse is also associated with a significantly lower risk of relapse compared with those who never received an allogeneic HCT. With the current duration of followup, OS is not significantly different across the three groups. These data suggest there is a benefit for relapse-free survival in pts receiving an allogeneic HCT at some point in the course of treatment for r/r Ph neg B-ALL.