Citations

Abstract Background and Significance: CMML is a myeloid neoplasm characterized by hematopoietic stem and progenitor cell (HSPCs) monocytic bias, leading to downstream monocyte expansion that plays a key role in disease maintenance and progression. Monocytes in CMML express high surface expression of the homing C-C chemokine receptor 2 (CCR2), which promotes malignant monocyte survival. Expansion of CCR2+ monocytic progenitors drives acute transformation in CMML and contributes to venetoclax resistance in AML. For these reasons, CCR2 is a potential novel therapeutic target in CMML and monocytic AML. The CyTAC platform was designed to enable targeting of cell surface antigens that demonstrate limited or ineffective binding to conventional therapeutic antibodies. A CyTAC is a heterobivalent small molecule that binds to both a target of choice and to a fully humanized monoclonal antibody. STX-0712 comprises a CCR2 CyTAC which potently binds to CCR2 on malignant cells, and a CyTAC humanized ADCC-enabling monoclonal antibody, which when combined eliminates target cells via enhanced effector-mediated killing in the presence of NK cells. We have demonstrated that treatment with STX-0712 ex vivo results in human target engagement and pharmacodynamic activity, and in vivo leads to depletion of CCR2 MO1 monocytes in a potent and dose-dependent manner in CMML and AML (ASH 2024). Therapeutic depletion of CCR2+ malignant monocytes presents a novel opportunity to develop a potential disease-modifying targeted therapeutic agent. We have designed a first-in-human, phase 1 clinical trial to evaluate the effect of CCR2 CyTAC in patients with refractory/resistant CMML, and relapsed/refractory monocytic or monocytic predominant AML. Study Design and Methods This is a phase 1, first-in-human, open-label, multicenter clinical trial based in the USA to evaluate STX-0712 as a monotherapy in patients with CMML and AML who have no remaining treatment options known to confer clinical benefit. STX-0712 will be administered as a single intravenous (IV) infusion every 3 weeks (additional regimen schedules may be explored) until evidence of disease progression, death, intolerance to study medication, or withdrawal of consent. The study consists of a dose-escalation and dose-expansion part and includes two cohorts: Cohort 1 (refractory/resistant CMML) and Cohort 2 (relapsed/refractory monocytic or monocytic predominant AML). Dose escalation will begin in participants with CMML using the Bayesian Optimal Interval (BOIN) design, with a minimum of three patients enrolled at each dose level. Backfilling of up to two cleared dose levels will be initiated once efficacious exposure levels are reached and at least one CMML participant has achieved a complete remission (CR) or a partial remission (PR), marrow response, or clinical benefit as defined by the MDS/MPN IWG 2015 criteria. In the AML cohort, backfilling may begin once at least one participant has achieved a response defined by ELN 2022 criteria. Dose expansion will occur upon completion of dose escalation in each cohort, using a Simon 2-stage adaptive design. Approximately 47 CMML and 58 AML patients may be enrolled in this phase 1 study. The primary objectives of the study are to evaluate the safety and tolerability of STX-0712 and to determine the minimal safe and biologically effective dose, recommended phase 2 dose (RP2D), and/or maximum tolerated dose (MTD), and to characterize dose-limiting toxicities (DLTs). Secondary objectives include evaluation of preliminary antitumor activity, pharmacokinetic (PK) parameters, and pharmacodynamic effects of STX-0712 on CCR2+ malignant cells in blood and bone marrow. Key exploratory endpoints include: (1) assessment of changes in CCR2+ tumor cells following STX-0712 dosing, (2) evaluation of candidate biomarkers, (3) characterization of T cells, B cells and NK cells at baseline and over the course of treatment, and (4) to explore the effects of STX-0712 on patient-reported outcomes using the CMML Symptoms Assessment Tool (MPN-SAF-TSS scoring system) and the EuroQoL 5 Dimension 5 level (EQ-5D-5L) for AML. Enrollment for Cohort 1 (CMML) began in March 2025, and the study is ongoing. Clinical Trial Information: NCT06950034

Abstract BACKGROUND Ivosidenib is an oral inhibitor of mutant isocitrate dehydrogenase type I (IDH1) currently approved for the treatment of IDH1 mutated acute myeloid leukemia and myelodysplastic syndrome (MDS). Hematopoietic stem and progenitor cells carrying preleukemic mutations, referred to as clonal hematopoiesis (CH), are the origin of myeloid neoplasms (MN). Individuals who have cytopenias and CH, but do not meet diagnostic criteria for a hematologic malignancy, are classified as having Clonal Cytopenias of Undetermined Significance (CCUS), a condition associated with a high risk of progression to MN. While CCUS patients (pts) can have multiple mutations, they show lower mutational burden on average compared to MN. Thus, we hypothesized that treatment with ivosidenib would improve cytopenias in IDH1-mutant CCUS. METHODS; We performed a decentralized phase II single-arm study to characterize the safety and efficacy of ivosidenib in IDH1-mutant CCUS (NCT0503044). Drug was shipped to pts with local oncologists performing standard-of-care clinical exams supplemented by study team lead interviews for adverse event monitoring. Research labs were drawn by local providers or through Quest. QT corrected interval (QTc) was monitored through a mobile electrocardiogram device (AliveCor). Eligible patients were aged ≥ 18 years and had confirmed IDH1-mutant CCUS with at least 6 months of unexplained cytopenias (hemoglobin<10 g/dL, platelets<100 x109/L or absolute neutrophil count <1.8 x109/L). The primary endpoint was hematologic response of at least 8 weeks in duration based on the IWG 2006 criteria for MDS. RESULTS 20 pts with IDH1-mutant CCUS have been enrolled. Most were male (70%) with a median age of 66 (range 41-79). Overall, 74% had a self-reported race of non-Hispanic white, 11% of Hispanic white, 5% of Asian and 11% of black or African American. Most pts presented with neutropenia (95%) including some with co-occurring thrombocytopenia (21%). One pt presented with anemia and thrombocytopenia without neutropenia. Prior to treatment, the average number of co-mutations beyond IDH1 was 2 (range 0-3), with most pts (74%) harboring a co-occurring spliceosome gene mutation. The IDH1 variant allele fraction (VAF) was lower in the blood (mean=19%, range 3-35%) than in the bone marrow (mean=31%, range 18-43%) in most (93%) patients. Out of the 20 enrolled pts, 17 received at least 8 weeks of therapy at the time of our data cutoff (7/29/2025) and were included in the efficacy analysis. Grade ≥3 adverse events (AEs) occurred in five patients (26%) including two with grade ≥3 treatment-related adverse events (pancytopenia and sepsis in the first pt, rash in the second pt). The most common all-grade treatment-related adverse events were nausea (n=5, 26%), prolonged QTc (n=3, 16%), anemia (n=3, 16%), and diarrhea (n=3, 16%). There were no instances of reported differentiation syndrome. Overall, 82% of pts achieved a hematologic response (14/17) including improvement in neutropenia (88%) and thrombocytopenia (75%). With a median follow-up of 16 months (range 0.6-24 months), the median duration of hematologic response was not reached. Among responders, 86% had a continued response at one year. Two pts progressed to MDS after 4 and 17 months of treatment characterized by recurrence of cytopenias and the emergence of new clones. A surveillance bone marrow biopsy was performed at 18 cycles for the 8 pts who remained on treatment with none showing disease progression. Most pts (90%, N=9/10) treated for at least 12 months had a decrease in IDH1-mutant CH VAF over time and 40% (N=4/10) showed IDH1 mutation clearance (VAF <2%) with a median time to clearance of 9 months. Among those with decreasing IDH1 clonal burden, all had a corresponding decrease in other co-occurring mutations present at baseline with one responder showing emergence of a newly detectable CHEK2 mutation without disease progression. CONCLUSIONS Decentralized trials represent a feasible solution for the conduct of clinical trials in rare hematologic neoplasms and precursor conditions. Ivosidenib was well-tolerated and induced durable hematologic remissions in IDH1-mutant CCUS. Most pts showed a reduction in clonal burden with mutation clearance commonly seen with long-term treatment demonstrating that ivosidenib modifies the natural history of IDH1-mutant CCUS.

Abstract Background Mosaic chromosomal alterations (mCAs) are large-scale somatic gains, losses, or copy-neutral loss of heterozygosity (CNLOH) detectable by genotyping of peripheral blood DNA. They represent a form of clonal hematopoiesis and are observed in 0.5-5% of cancer-free individuals. The presence of any autosomal mCA has been associated with >3-fold risk of hematological malignancies. In particular, mCAs occurring in regions related to lymphoid malignancies have an 11-fold increased risk of lymphoid malignancies and a 68.6-fold risk for chronic lymphocytic leukemia (CLL). Monoclonal B-cell lymphocytosis (MBL), the precursor state to CLL, is defined by <5×10⁹/L clonal B cells in otherwise healthy individuals and is classified as low-count (<0.5x109/L) or high-count (0.5-5x10⁹/L) based on clonal B-cell count. MBL is also associated with increased risk of lymphoid malignancy (beyond CLL), with 4.3-fold and 74-fold risk in individuals with low- and high-count MBL, respectively. We previously reported a significant enrichment of autosomal mCAs in MBL, demonstrating a 1.7-fold association in those with low-count MBL and a 50.5-fold association in those with high-count MBL. Whether mCAs independently predict lymphoid malignancy risk after accounting for MBL status is unknown. Here, we evaluated the impact of mCAs on risk of incident lymphoid malignancies in individuals with MBL and in individuals screened negative for MBL. Methods CLL-type MBL (CD5 positive) was identified using flow cytometry assay on peripheral blood. Participants were age ≥40, had no prior hematologic malignancy, and were enrolled through the Mayo Clinic Biobank or the Division of Hematology at Mayo Clinic, Rochester. Participants were followed for incident lymphoid malignancy, including CLL, with diagnoses confirmed by medical record review. mCAs with cell fraction >1% were detected from array-based genotyping of whole blood DNA. Cox proportional hazards models, adjusted for age and sex, estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for risk of developing an incident lymphoid malignancy in individuals with autosomal mCA versus those without an autosomal mCA. Results In 4,331 participants with available MBL and mCA status, the median age was 67 years, and 45% were male. Flow cytometry identified 3,231 individuals who screened negative for MBL, 754 individuals with low-count MBL, and 346 individuals with high-count MBL. Autosomal mCAs were present in 6.5% of individuals without MBL, 7.6% with low-count MBL, and 71.1% with high-count MBL. Over a median follow-up of 6.9 years, 237 individuals developed an incident lymphoid malignancy. The most common types were CLL, multiple myeloma, and diffuse large B-cell lymphoma. Ignoring MBL status, the presence of an autosomal mCA was associated with increased risk of lymphoid malignancy (HR = 2.65; 95% CI: 1.45–4.86; P = 0.002), replicating previous results. However, after excluding individuals with MBL, this association attenuated; those with mCA alone did not have a significantly elevated risk (HR = 1.60; 95% CI: 0.57-4.52; P = 0.38) compared to individuals without MBL or mCA. We next examined the effect of mCAs among individuals with MBL. In those with low-count MBL, the most frequent mCA events were 13q loss (2.1%), 12 gain (1.9%), and 4q CNLOH (1.2%), and individuals with an mCA had a borderline significant risk of developing a lymphoid malignancy (HR = 2.78; 95% CI: 1.01–7.67; P = 0.049) compared to those without an mCA. Similarly, in those with high-count MBL, the most frequent mCA events were 13q loss/CNLOH (31.2%), 12 gain (13.0%), and 11q loss (4.9%), and the presence of an mCA conferred an increased risk compared to those without mCA (HR = 1.51; 95% CI: 1.09-2.08; P = 0.012). Conclusions Autosomal mCAs were more frequent in individuals with high-count MBL compared to those with low-count or no MBL. mCAs showed limited predictive value for lymphoid malignancy among individuals without MBL. In contrast, in individuals with low-count MBL, autosomal mCAs emerged as a potential biomarker for identifying those at risk of developing a lymphoid malignancy. In high-count MBL, mCAs were also a biomarker, but were driven by known chromosomal abnormalities identified through clinical testing. These findings suggest that the utility of mCAs as a predictive marker for lymphoid malignancy is contingent on the presence of MBL and may inform risk stratification and surveillance strategies in this population.

Abstract Acute myocardial infarction complicated by cardiogenic shock (AMI-CS) is a heterogeneous clinical syndrome associated with substantial morbidity and mortality. We developed a machine learning-based mortality model to identify features and patient subgroups associated with the largest change in mortality risk when evaluating treatment with Impella devices or intra-aortic Balloon Pump (IABP). Our cohort comprised 369 sites and 15,796 patient visits to the cardiac catheterization laboratory from the National Cardiovascular Data Registry. The estimated population mean excess mortality effect of treatment with Impella devices vs IABP was 10.4 ± 0.8%. However, we identified clinical subgroups of 282 patients for whom a decreased risk of mortality was associated with use of Impella as compared with IABP. Those patients were on average younger, presented with higher systolic blood pressure, higher rate of salvage percutaneous coronary intervention, higher initial creatinine, and lower hemoglobin. While Impella devices were associated with higher mortality risk overall, certain clinical profiles were associated with lower risk, illustrating heterogeneity of treatment effects.

Importance Treatment for cognitive dysfunction due to postacute sequelae of long COVID (ie, symptoms of fatigue, malaise, weakness, confusion that persist beyond 12 weeks after an initial COVID infection) remains a significant unmet need. Objective To test evidence-based rehabilitation strategies for improving cognitive symptoms in persons with long COVID. Design, Setting, and Participants This was a 5-arm, multicenter, randomized clinical trial of 3 remotely delivered interventions conducted between August 17, 2023, and June 10, 2024. The study took place at 22 trial sites and included the screening of individuals with cognitive long COVID. Interventions Participants were randomized to 1 of 5 arms: adaptive computerized cognitive training (BrainHQ [Posit Science]), cognitive-behavioral rehabilitation involving both group and individual counseling sessions (PASC-Cognitive Recovery [PASC-CoRE]) paired with BrainHQ, and transcranial direct current stimulation (tDCS) paired with BrainHQ. Two comparator arms were included as follows: unstructured computer puzzles and games (active comparator) and sham tDCS paired with BrainHQ. The interventions occurred 5 times per week over 10 weeks. Main Outcomes and Measures Cognitive and behavioral in-person assessments were performed at baseline, midintervention, at the end of intervention, and 3 months after the end of the intervention. The primary outcome measure was the modified Everyday Cognition Scale 2 (ECog2) completed at the end of the intervention compared to the baseline visit based on participant self-report looking back over the prior 7 days. Results A total of 378 individuals were screened, from which there were 328 participants (median [IQR] age, 48.0 [37.0-58.0] years; 241 female [73.5%]; race: 15 Asian [4.6%], 47 Black [14.3%], and 235 White [71.6%]; ethnicity: 52 Hispanic [15.9%]). None of the 3 active interventions demonstrated benefits on the modified ECog2 in the intention-to-treat population by the end of the intervention period. The adjusted differences in mean change were 0.0 (95% CI, −0.2 to 0.2) for BrainHQ vs active comparator, 0.1 (95% CI, −0.1 to 0.3) for PASC-CoRE + BrainHQ vs active comparator, 0.0 (95% CI, −0.2 to 0.2) for tDCS-active + BrainHQ vs tDCS-sham + BrainHQ, and 0.1 (95% CI, −0.1 to 0.3) for PASC-CoRE + BrainHQ vs BrainHQ alone. Secondary participant-reported outcomes and neuropsychological tests showed no differential benefits for any treatment arm. All 5 arms demonstrated some improvements over time on the modified ECog2 and on secondary outcomes. There were no serious adverse events attributable to the interventions. Conclusions and Relevance This phase 2 randomized clinical trial failed to demonstrate differential benefits for online cognitive training, a structured cognitive rehabilitation program, and tDCS for cognitive long COVID. Trial Registration ClinicalTrials.gov Identifier: NCT05965739 .

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 Importance The addition of agents targeting critical signal mediators of cancer cell proliferation such as cyclin-dependent kinases (CDK) potentiates the efficacy of platinum chemotherapy. Objective To determine the safety and efficacy of palbociclib combined with cisplatin (cis) or carboplatin (carbo) in advanced solid malignancies Design Enrollment on dose escalation (part I) proceeded using the Bayesian adaptive design Escalation with Overdose Control (EWOC). Setting Single institution investigator initiated trial. Participants Patients with any advanced cancer after at least one prior therapy were enrolled on dose escalation to determine recommended phase II doses (RP2D). Expansion cohorts were then opened for pancreaticobiliary tract cancers. Intervention Escalating doses of palbociclib in combination with different doses of cisplatin or carboplatin. Main Outcomes and Measures Primary endpoint was objective response rate (ORR). Secondary endpoints included safety, overall survival (OS), and progression-free survival (PFS). Results We enrolled 39 patients on dose escalation (part I) and 32 additional patients on dose expansion (part II). RP2D of palbociclib 100 mg on Day 2-22 + Cisplatin (cis) 60 mg/m2 IV on Day 1 Q4W (Arm A); and palbociclib 75 mg on Day 2-22 + Carboplatin (carbo) AUC 6 IV on Day 1 Q4W (Arm B). ORR for Part I were 12.5% (Arm A) and 25% (Arm B). Median PFS and OS for dose expansion were 2.1 and 4.9 months, respectively. For PDAC, mPFS was 1.9 months (95% CI: 1.7, 2.4), and OS was 3.7 months (95% CI: 2.7, 5.7). Most common treatment-related adverse events (TRAEs—all grade %): Arm A—neutropenia (66%), thrombocytopenia (26%), nausea, fatigue, and anemia (20% each); Arm B—neutropenia (64.7%), thrombocytopenia (53%), and anemia (29%). There were no grade 4-5 TRAEs. Conclusions and Relevance The combination of palbociclib with cisplatin or carboplatin had an acceptable safety profile and clinical responses in some treatment refractory advanced cancers. There was no objective response, but about half of PDAC patients had disease stabilization. Additional efforts are needed to exploit CDK abnormalities in these patients. Clinical trial registration number: NCT02897375

Abstract Despite advances in immunotherapy, high-grade serous ovarian cancer (OC) remains largely refractory to current treatments. The diversity of antigens expressed in OC has not been fully elucidated, limiting targeted approaches. Using immunopeptidomic profiling of HLA-A02:01+ OC cell lines and metastatic patient samples, we sought to identify a broader range of actionable antigens. Among canonical tumor-associated peptides, we found epitopes from TTLL8, POTEE, and PKMYT1—proteins with minimal expression in normal tissues but elevated in OC. TTLL8, in particular, correlated with poor prognosis and elicited robust CD8+ T cell responses, underscoring its immunogenic potential. In a separate study, we detected 311 cryptic (noncanonical) peptides derived from noncoding genomic regions across five metastatic OC tumor samples. Although representing <1% of total peptides, these cryptic antigens dominated the immunogenic landscape, with nearly 70% inducing autologous CD8+ T cell activation, as measured by 4-1BB and IFN-γ expression. Together, these findings expand the antigenic repertoire of OC and support the development of new immunotherapies targeting both canonical and cryptic tumor antigens. Citation Format: Marion Curtis. Cracking the code: Identifying immunogenic targets in high-grade serous ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Ovarian Cancer Research; 2025 Sep 19-21; Denver, CO. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl):Abstract nr IA019.

Abstract Background: Despite the success of chimeric antigen receptor (CAR) T cell therapy in hematological malignancies, its efficacy in solid tumors remains limited. Macrophages, as key players in the innate immune response, offer unique advantages in the solid tumor context due to their ability to infiltrate tissues and phagocytose tumor cells. Preclinical studies have demonstrated that CAR-engineered macrophages (CAR-Ms) can penetrate solid tumors, initiate phagocytosis, and promote adaptive immunity. Early-phase clinical trials infusing CAR-Ms into patients have shown a favorable safety profile. However, within the immunosuppressive tumor microenvironment (TME), macrophages are often reprogrammed into tumor-promoting, M2-like tumor-associated macrophages (TAMs), which limit their therapeutic efficacy. Metabolic reprogramming is a critical driver of this polarization and TCA derived succinate has been shown to promote M1 phenotype in macrophages. In this study, we investigate whether succinate-loaded nanoparticles (PES NPs) can metabolically rewire CAR-Ms to maintain a pro-inflammatory (M1-like) phenotype and enhance antitumor activity in ovarian cancer (OC). Results: We synthesized polyethylene succinate (PES) nanoparticles (NPs) and analyzed their size, polydispersity, and zeta (ζ) potential using dynamic light scattering (DLS). The results showed a negative potential, indicative of stability, and suggested that succinate could be effectively encapsulated in nanoparticles. OC cells abundantly express mesothelin protein; therefore, mesothelin-targeting CARs were chosen to transfect mouse bone marrow-derived macrophages (BMDMs) or human monocyte-derived macrophages (HMDMs) to generate CAR-Ms. Our results showed that mouse and human CAR-Ms treated with PES NPs exhibited increased mitochondrial respiration and glycolysis, seen as elevated ECAR and OCR relative to vehicle control or cell-permeable dimethyl succinate ester (DMSA). Flow cytometry analysis revealed that PES treatment resulted in increased expression of markers of the classical M1 phenotype in both mouse and human CAR-Ms. The CAR-Ms also had elevated mRNA levels of proinflammatory cytokines like IL-6, TNFα, and IL1β, while anti-inflammatory cytokines like IL-10 remained low. Furthermore, IL-4-induced M2-like CAR-Ms could be reversed to an M1-like phenotype by PES NPs. Consistent with these results, PES NP-treated CAR-Ms exhibited increased phagocytic activity toward OC cells expressing mesothelin. Building on these in vitro results, the effect of PES NP-treated CAR-Ms on the reduction of tumor growth in OC tumor models will be further investigated. Conclusions: Our findings demonstrate that PES NPs effectively reprogram CAR-Ms to maintain a pro-inflammatory M1 phenotype. This reprogramming enhances their phagocytic activity and target cell killing in vitro. Collectively, these results support intracellular succinate delivery as a promising strategy to improve the efficacy of CAR-M-based therapies in OC. Citation Format: Remya Raja, Alexis Hand, Madhan Mohan Chandra Sekhar Jaggarapu, Jason Tonne, Richard Vile, Abhinav Acharya, Marion Curtis. Succinate based metabolic reprogramming of CAR-macrophages for ovarian cancer immunotherapy [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Ovarian Cancer Research; 2025 Sep 19-21; Denver, CO. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl):Abstract nr B063.