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Abstract Background: Partial tandem duplications of the histone methyltransferase KMT2Agene(KMT2A-PTD) are the most common KMT2A-aberration in adult acute myeloid leukemia (AML). KMT2A-PTD AML represents a high-risk disease subset with a poor prognosis. However, KMT2A-PTD leukemia is under studied, likely due to a lack of experimental models, and therefore the underlying mechanisms of leukemogenesis remain elusive. Since KMT2A-PTD leukemias possess high-level expression of HOXAgenes, similar to KMT2A-rearranged (KMT2A-r) and NPM1c AML, patients with this type of AML are currently enrolled into several phase I/II trials assessing menin inhibitors (MIs). However, mechanistic or clinical evidence for treatment response is lacking. To date, no targeted therapeutic approaches for KMT2A-PTD leukemia are available. Results: To better understand KMT2A-PTD mediated leukemogenesis, we endogenously tagged the KMT2A-PTD or KMT2A-wildtype (WT) allele in EOL-1 cells with a dTAG that can be degraded with PROTACs. Targeted protein degradation showed that the KMT2A-PTD, but not the KMT2A-WT protein, is critical to maintain leukemia cell growth. We identified KMT2A-PTD specific genome-wide chromatin binding sites and direct target genes as assessed by changes in nascent RNA production that started to occur within 30 minutes of KMT2A-PTD degradation. KMT2A-PTD target genes identified in this study included HOXA9, HMX2, HMX3, CDKN2C, MYC and CDK6 among others. Having defined the KMT2A-PTD target gene program, we assessed the effect of MI on KMT2A-PTD function. In KMT2A-PTD cell lines, PDXs and cells from a published murine KMT2A-PTD/FLT3-ITD knockin model, we observed intrinsic resistance to revumenib characterized by retained chromatin binding of KMT2A-PTD, but not KMT2A-WT after MI treatment. We next defined critical domains for KMT2A-PTD function via a KMT2A domain scan. This revealed the CXXC domain and AT hooks as critical dependencies in EOL-1 cells. Overexpression of KMT2A or mutants with duplicated domains in 293T cells showed that a duplication of the CXXC domain or the AT hooks is sufficient to mediate retained KMT2A chromatin binding under MI. Therefore, the resistance to MIs is likely due to the duplicated protein of KMT2A subverting menin function at critical target loci. Given that KMT2A-PTD remains chromatin-bound upon menin inhibition, we focused on ENL as a potential regulator of leukemia gene expression programs. In KMT2A-r and NPM1c leukemia, the ENL protein has been shown to be a critical dependency as it associates with acetyl lysine via its YEATS domain. ENL/AF9 YEATS inhibitors reverse ENL-dependent gene expression including HOXA9 and MYC. Using the small molecules TDI-11055 and TM-7, we show that YEATS inhibition leads to loss of members of the super-elongation complex and DOT1L from KMT2A-PTD driven loci and downregulation of target gene expression. Treatment of KMT2A-PTD PDXs with YEATS inhibitors induced differentiation and significantly reduced leukemia burden in vivo. Interestingly, we show that in contrast to previous findings in KMT2A-r leukemia, loss of ENL alone is insufficient to abrogate leukemic proliferation of EOL-1 cells. Instead, by combining ENL degradation with CRISPR-Cas9 mediated knockdown of AF9, we find that both YEATS proteins, ENL and its paralogue AF9, support aberrant gene expression in KMT2A-PTD leukemia. Finally, we show that the novel combination of MI and YEATS inhibition (revumenib plus TDI-11055) synergistically affects proliferation and induces differentiation in cell line and PDX models of KMT2A-PTD leukemia, which in turn prolongs survival of mice with KMT2A-PTD leukemia. Conclusions: KMT2A-PTD leukemia is dependent on the mutated, but not the WT KMT2A allele. It is characterized by a relative, intrinsic resistance to MI monotherapy, which is mediated by a duplication of the CXXC domain and AT hooks of KMT2A. Targeting both, the ENL and AF9 YEATS domain, is a possible treatment strategy and when combined with revumenib, YEATS inhibition has synergistic effects and overcomes intrinsic MI resistance. However, based on our studies, MI monotherapy may not be effective for most patients with KMT2A-PTD leukemia. Given that numerous compounds targeting the ENL (and AF9) YEATS domain are under study and MIs have recently obtained FDA approval, the combination of MI and YEATS inhibition could be translated into clinical trials for patients with KMT2A-PTD leukemia in the relatively near future.

Abstract Introduction Mature T-cell lymphomas, including aggressive nodal PTCL, advanced stage CTCL, and extranodal cytotoxic lymphomas, are associated with poor outcomes. While karyotype (KT) abnormalities are frequently detected in these diseases, limited data exist on their prognostic significance. We evaluated the impact of KT abnormalities, including complex KT and specific chromosomal lesions, along with clinical and demographic factors, on overall survival (OS) in a single-center cohort. Methods We retrospectively reviewed 189 patients (pts) diagnosed with T-cell lymphoma who had successful metaphase KT at diagnosis from peripheral blood (PB), bone marrow (BM), or tumor tissue. T-cell lymphomas were classified according to WHO 2022 into nodal, extranodal/cytotoxic, and cutaneous subtypes. CTCLs were stratified into indolent (Early-stage CTCL, IA–IB) and aggressive (Sézary syndrome, transformed mycosis fungoides). KTs classified as normal, abnormal, and complex (≥3 abnormalities), and recurrent abnormalities were recorded. Baseline clinical and lab data were collected. OS was estimated using the Kaplan-Meier (KM) method with 95% confidence intervals (CI). Univariate Cox proportional hazards (CPH) model identified factors associated with OS, and significant variables were entered into multivariate CPH models. Results The median age was 66 years (IQR 55-74); 65% were male and 35% were female. Overall, 58% of pts were alive at analysis. Nodal PTCL was the most common subtype (113 pts, 60%), followed by early CTCL (30, 16%), aggressive CTCL (24, 13%), and extranodal lymphomas (22, 12%). KT was obtained from 166 BM (86%), 26 PB (13%), and 2 tissue (1%) specimens. Among abnormal KTs, 63% were from BM, 35% from PB, and 2% from tissue. Specific abnormalities included gain of chr1 (5%), gain of chr3 (5%), gain of chr7 (5%), gain of chr8 (5%), monosomy 5 or del(5q) (4%), monosomy 9 or del(9q13q22) (4%), Monosomy 10 (4%), loss of chrY (5%), and presence of marker chromosomes (5%).Of the 189 pts, 48 (25%) had an abnormal KT, while 141 (75%) had a normal KT. Complex KT was observed in 31 (16%) pts. Abnormal non-complex and complex KTs were seen respectively in: aggressive CTCL (8%, 42%), nodal PTCL (4%, 13%), extranodal (9%, 14%), and early CTCL (27%, 10%). KM survival analysis showed a median OS for the entire cohort of 95 months (95% CI: 65-245). Pts with a normal KT had a median OS of 143 months (95% CI: 81-inf) compared with 34 months (95% CI: 18-83) for those with an abnormal KT. Pts without a complex KT had a median OS of 144 months (95% CI: 85-inf), whereas those with a complex KT had 14 months (95% CI: 4-25). For specific abnormalities, pts with gain of chr7 had OS of 3 months, gain of chr8 had 19 months, monosomy 5 or del(5q) had 4 months, loss of chrY had 30 months, gain of chr1 had 4.5 months, gain of chr3 had 7.5 months, monosomy 9 or del(9q13q22) had 2 months, monosomy 10 had 17 months, and marker chromosome presence had 5.5 months. Univariate CPH identified complex KT (HR = 3.9, p < 0.001), gain of chr1 (HR = 5.7, p < 0.001), gain of chr3 (HR = 4.6, p < 0.001), monosomy 5 or del(5q) (HR = 4.6, p < 0.001), gain of chr7 (HR = 4.2, p < 0.001), gain of chr8 (HR = 3.3, p < 0.001), monosomy 9 or del(9q13q22) (HR = 4.9, p < 0.001), monosomy 10 (HR = 2.8, p = 0.008), and marker chromosomes (HR = 4.6, p < 0.001) as adverse factors. Higher platelet count was protective (HR = 0.9, p < 0.001), while greater number of abnormalities increased hazard (HR = 1.1, p < 0.001). In multivariate CPH model, complex KT (HR = 3.1, 95% CI: 1.2-8.2, p = 0.019), monosomy 9 or del(9q13q22) (HR = 4.4, 95% CI: 1.2-15.4, p = 0.022), gain of chr1 (HR = 3.5, 95% CI: 1.1-11.8, p = 0.042), and low platelet count (HR = 0.98, 95% CI: 0.97-0.99, p = 0.006) remained independent predictors of poor OS. Conclusion: We demonstrate that cytogenetic abnormalities detected in PB or BM, most notably complex KTs, confer a markedly poor prognosis in aggressive T-cell lymphomas. The integration of KT data with clinical parameters, such as platelet count, offers a powerful approach to refine risk stratification, identify biologically high-risk subgroups, and potentially guide personalized therapeutic strategies in this challenging disease spectrum. To our knowledge, this is one of the largest single-center studies assessing the prognostic significance of KT in mature T-cell lymphomas, providing novel insights into the role of specific chromosomal lesions in patient outcomes.

PURPOSE STELLAR (ClinicalTrials.gov identifier: NCT02796261 ) was a phase III, randomized, open-label trial of eflornithine + lomustine versus lomustine monotherapy in patients with recurrent grade 3 astrocytoma. METHODS At trial initiation, eligibility criteria included: age ≥18 years, anaplastic astrocytoma (2016 WHO CNS Tumor classification [WHO CNS4]), first recurrence ≥6 months after radiation and temozolomide (TMZ), Karnofsky performance status ≥70, and no imaging findings consistent with grade 4 glioblastoma. Random assignment (1:1) was stratified by isocitrate dehydrogenase ( IDH ) mutation, age, resection extent, and geography. Patients received eflornithine (2.8 g/m 2 orally, every 8 hours [2 weeks on, 1 week off]) + lomustine (90 mg/m 2 orally, once every 6 weeks), or lomustine monotherapy (110 mg/m 2 once every 6 weeks). The primary end point was overall survival (OS). RESULTS Among 343 patients randomly assigned across 74 sites in eight countries, there was no difference in survival between eflornithine + lomustine and lomustine monotherapy (median OS 23.4 v 20.3 months, hazard ratio [HR], 0.94). Following changes in classification and grading in the 2021 WHO CNS5, a subset analysis of patients with IDH- mutant, grade 3 astrocytoma (n = 196), defined in 2024, before unblinding, showed clinically meaningful improvements in median OS with eflornithine + lomustine versus lomustine monotherapy (34.9 v 23.5 months, HR, 0.64) and median progression-free survival (PFS, 15.8 v 7.2 months, HR, 0.57). No differences were observed among patients with CNS grade 4 disease. Grade ≥3 treatment-emergent adverse events of relevance were related to reversible myelosuppression (eflornithine + lomustine 42% v lomustine monotherapy 29% of patients) and hearing impairment (24% v 0%). No new safety signals were identified. CONCLUSION Clinically meaningful improvements were observed; eflornithine + lomustine doubled PFS and improved OS in patients with recurrent IDH -mutant, grade 3 astrocytoma, but not grade 4 tumors, after prior radiotherapy and TMZ, consistent with its cytostatic mechanism of action.

Abstract Background This phase 1 study aimed to determine the maximum tolerated dose (MTD) and evaluate the safety and preliminary efficacy of rucaparib (RUB), a poly(adenosine diphosphate ribose) polymerase (PARP) inhibitor, combined with liposomal irinotecan (nal‐IRI) and 5‐fluorouracil (5‐FU) in metastatic gastrointestinal (GI) cancers. RUB targets DNA repair pathways, showing efficacy in tumors with homologous recombination deficiency, such as BRCA mutations. Preclinical data suggest synergy with irinotecan, but overlapping toxicities pose challenges. Methods Eighteen patients with metastatic GI cancers, who previously progressed on at least one systemic therapy, were enrolled. A novel sequential dosing regimen, informed by nal‐IRI pharmacokinetic analysis, was used. Twelve patients were evaluable for dose‐limiting toxicity (DLT) and 12 for response per Response Evaluation Criteria in Solid Tumors v1.1 criteria. Results The MTD was established as RUB 600 mg twice daily, nal‐IRI 50 mg/m 2 , and 5‐FU 2400 mg/m 2 over 46 hours. The objective response rate (ORR) was 33% (4 of 12), and the disease control rate (DCR) was 75% (9 of 12). Common grade 3 adverse events included diarrhea (33%) and neutropenia (25%), with no grade 4/5 events. Responses were notable in patients with somatic ATM and BRCA mutations, especially those with prior platinum exposure. No DLTs occurred at the recommended phase 2 dose. Conclusions This optimized dosing schedule successfully established the MTD for RUB with nal‐IRI and 5‐FU, overcoming prior challenges with PARP inhibitor and irinotecan combinations. The promising ORR and DCR support further evaluation of this regimen in advanced GI malignancies.

Abstract Background DNA methylation profiling can be used to robustly predict postsurgical outcomes and response to radiotherapy (RT) for meningioma patients. To allow for seamless integration of these complementary models into clinical practice, a practical framework is needed. Methods We leveraged a cohort of nearly 2000 surgically-treated meningiomas with DNA methylation profiling and clinical outcomes data. Existing methylation-based prediction models were dichotomized to yield four risk groups: low and high recurrent risk, each with RT sensitive and resistant subgroups. Risk groups were correlated with progression-free survival in the context of existing biomarkers including extent of resection and WHO grade. Results We first demonstrated that all risk groups benefit from gross total resection. All “high-risk, RT sensitive” tumors (n = 306, 15.7%) also benefited from adjuvant RT: after GTR, median PFS increased from 4.68 (4.13-9.48) years to not reached (P = .003); after subtotal resection (STR), from 2.12 (1.59-3.02) to 4.09 (3.41-not reached) years (P = .004). “Low-risk, RT sensitive cases” (n = 1207, 61.8%) also benefited from RT after STR (median PFS 7.39 (6.66-12.8) vs. 16.53 (10.35-not reached) years, P = .03), suggesting that RT be considered in these patients. Neither “low-risk RT resistant” (n = 84, 4.3%) nor “high-risk RT resistant” (n = 356, 18.2%) cases benefited from RT, and the latter group was associated with universally poor outcomes. Conclusions We identify methylation-defined risk groups of meningioma for which additional benefit is gained from adjuvant RT, leading to a clinical decision-making framework for straightforward integration of molecular models into clinical practice.

Abstract BACKGROUND While most meningiomas are classified as low-grade tumors with indolent behavior, a subset is characterized by a more aggressive clinical course and patients undergo repeated resections and courses of radiation. Once these therapies fail, prognosis is poor and progression-free survival (PFS) rates at 6 months (PFS-6) are estimated to only be 43.6% for WHO grade 1 and 38% for WHO grade 2/3 meningiomas. Effective medical therapies are limited. Somatostatin receptor 2 (SSTR2) is expressed in a majority of meningiomas and represents a suitable treatment target. [177Lu]Lu-DOTA-TATE (177Lu-Dotatate) is an SSTR2-targeted radioligand therapy, established as standard of care in the treatment of certain neuroendocrine tumors. Two ongoing non-randomized studies of 177Lu-Dotatate in meningiomas have reported encouraging efficacy compared to historical benchmarks. METHODS/STUDY DESIGN The MOMENTUM-1 study (RTOG 3523, NCT#06955169) is a multicenter, randomized, open-label study of 177Lu-Dotatate in adult patients with progressive intracranial WHO grade 1-3 meningiomas. Up to 130 eligible subjects are randomized in a 2:1 fashion to 177Lu-Dotatate at 7.4 GBq (200 mCi) every 4 weeks for 4 (+2 optional) doses or standard of care (SOC) medical therapy as defined by the protocol and deemed appropriate by the local investigator. Treatment responses are assessed by gadolinium-enhanced MRI brain and [68Ga]Ga-DOTA-TATE (68Ga-Dotatate) PET imaging. At time of progression, cross-over from the SOC to the interventional treatment arm is allowed. The primary endpoint is PFS. Secondary endpoints include PFS-6, OS-12, OS, response assessments (ORR, DCR), safety/tolerability, and patient-reported outcomes. RESULTS/CONCLUSION MOMENTUM-1 is a multicenter, randomized, open-label, phase II study of 177Lu-Dotatate in adult patients with progressive WHO grade 1-3 meningioma. This clinical trial is expected to start enrolling patients in the United States in the third quarter of 2025. Details on study design, eligibility criteria for subject enrollment and study site eligibility criteria will be presented.

Abstract IDH-wildtype diffuse astrocytic gliomas with lower-grade histological features alongside specific genomic alterations (e.g., TERT promoter mutation, EGFR amplification, gain Chr7/loss Chr10) are presently diagnosed as glioblastoma, IDH-wildtype (GBM) under WHO 2021 criteria. Previous analyses categorized these into “early/evolving” or “surgically undersampled” GBMs. However, it remains unclear whether these tumors share identical clinical and prognostic features with histologic GBM. Data from IDH-wt molecular GBMs across six institutions were aggregated. Astrocytic IDH-wt tumors of any grade that lacked necrosis or microvascular proliferation on initial histopathology yet exhibited molecular alterations consistent with WHO 2021 GBM diagnosis, were included. Recursive partitioning analysis (RPA) was used to categorize patients into risk groups based on overall survival (OS). Among the 264 patients included, the median age was 60 years (IQR: 51-67), with 162 (61%) being male. Additionally, 210 (80%) were diagnosed since 2016, and 216 (82%) received chemoradiation plus adjuvant temozolomide (GBM-SOC). The median follow-up period was 3.9 years (95% CI: 3.4, 4.6). Identified univariate risk factors for worse survival included older age, biopsy-only status, EGFR amplification, absence of initial adjuvant treatment, low post-operative KPS, and tumor histologic grade of 3. RPA divided patients into four distinct survival groups (p<0.0001). The “best” risk group comprised lower grade (<=2) tumors (n=58, median OS (mOS): 40 months (95% CI: 33, NA)). The “second best” group included Grade 3 patients receiving GBM-SOC without steroids during initial RT (n=139, mOS: 25 months (95% CI: 22, 28)). The “second worst” group encompassed Grade 3 patients who were on steroids during initial RT while receiving GBM-SOC (n=38, mOS: 15 months (95% CI: 13, 20)). The “worst” group contained Grade 3 tumors that had not undergone SOC (n=29, mOS: 9 months (95% CI: 4, 26)). These data show that histologic features and treatment are strong indicators of patient outcomes.

Abstract BACKGROUND STELLAR was a phase III randomized, open-label trial of eflornithine (ornithine decarboxylase inhibitor) with lomustine versus lomustine alone in patients with recurrent anaplastic astrocytoma (AA). We previously reported an overall survival (OS) and progression free survival (PFS) of the combination in the patients with grade 3 IDH-mutant astrocytoma. Here we report updated OS and PFS outcomes based on additional molecular classification and blinded independent central review (BICR). METHOD Eligibility included: age ≥ 18 years, AA (2016 WHO criteria) with first recurrence ≥ 6 months after radiation, KPS ≥ 70, and no imaging findings consistent with grade 4 glioblastoma. Patients received eflornithine (2.8 g/m2 TID Q 2/3 weeks) with lomustine (90 mg/m2 Q 6 weeks) (Arm A) or lomustine alone (110 mg/m2 Q 6 weeks) (Arm B). Primary endpoint was OS. RESULTS Updated molecular data resulted in re-classification of the 343 AA patients enrolled into 3 WHO 2021 defined tumor subtypes, 196 tumors were IDHmut, CDKN2A/B intact, consistent with diagnosis of astrocytoma, IDHmut, WHO grade 3, 33 tumors had CDKN2A/B loss consistent with astrocytoma, IDHmut, WHO grade 4, 106 tumors were IDHwt consistent with diagnosis of glioblastoma, IDHwt, WHO grade 4. Updated results strengthen initial conclusion that eflornithine plus lomustine resulted in significant survival benefit in the astrocytoma, IDHmut, WHO grade 3 group (mOS 34.9 vs, 23.5 months, HR = 0.64, stratified log rank p =0.0136). PFS with eflornithine was also improved (15.8 vs, 7.2 months, HR = 0.57, stratified log rank p =0.0113). BICR demonstrated a high correlation between investigator and centrally determined PFS (p=0.0305), and high correlation between OS and PFS (p=.0001). CONCLUSION The clinically meaningful OS and PFS benefits observed with eflornithine in the molecularly defined 2021 WHO CNS grade 3 astrocytomas is further confirmed and expanded based on additional molecular classification and BICR of PFS.

ABSTRACT BACKGROUND Platelet factor 4-polyanion enzyme-linked immunosorbent assays (ELISAs) are considered highly sensitive for diagnosing heparin-induced thrombocytopenia (HIT), such that current practice guidelines recommend use of ELISA-negative results to exclude HIT. Once HIT is ruled out, alternative, non-heparin-based anticoagulant treatments are ceased, and heparin reintroduction frequently occurs. METHODS Antigen-based and PF4-dependent functional testing were used to study PF4/polyvinyl sulfonate ELISA-negative platelet-activating antibodies in HIT-suspected patients and mice immunized with PF4/heparin. RESULTS Three patients with clinical presentations consistent with HIT tested negative in an ELISA using PF4-polyvinylsulfonate (PF4/PVS), an antigenic target very commonly used for HIT antibody detection. All three patients demonstrated PF4-dependent platelet activation in functional testing that was sensitive to blockade of platelet FcγRIIa receptors and inhibited by high concentrations of heparin, consistent with pathogenic HIT antibodies. Functional testing-based screening of 500 ELISA-negative patients identified three patients whose sera activated platelets in a PF4- and FcγRIIa-dependent manner, and had clinical histories consistent with HIT. Five of the six ELISA-negative HIT patients were re-exposed to heparin, which precipitated a decrease in platelet counts in all re-exposed patients, and one patient developed a new thrombus. To advance the study of ELISA-negative HIT antibodies, mice were immunized with PF4/heparin, and functional and antigenic assays were simultaneously used to successfully identify an ELISA-negative, PF4-dependent platelet-activating murine monoclonal antibody that recapitulated the serological characteristics of ELISA-negative HIT patients. CONCLUSIONS Recognition of ELISA-negative HIT is critical to avoid harm due to the cessation of alternative anticoagulation therapy and re-exposure of these patients to heparin.

ABSTRACT The American Society for Apheresis (ASFA) Attending Physician Subcommittee of the Physicians' Committee performed an annual review of articles published in 2024 related to apheresis medicine. The 10 seminal apheresis articles selected by the subcommittee members are summarized in this review. PubMed was used to identify manuscripts published in 2024 in four areas of interest: donor apheresis, therapeutic apheresis, apheresis education, and apheresis for cellular therapy. Only full length, peer‐reviewed manuscripts in English with data from human subjects were included. Case reports, review articles, and meta‐analyses were excluded. Articles were considered seminal if they met at least one of the following previously established criteria: novel finding(s), practice‐altering outcomes, international in scope, randomized‐controlled trial, relevant to current clinical practice, and/or provide evidence for category III or IV indications based on the ASFA 9th special issue of the Guidelines on the Use of Therapeutic Apheresis in Clinical Practice‐Evidence‐Based Approach.