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Background In unfit patients (pts) with newly diagnosed (ND) AML, long-term survival remains short (mOS 14.7 months) despite improved responses (CR 37% and CR/CRi 66%) with azacitidine (AZA) and venetoclax (VEN) (VIALE-A, DiNardo NEJM 2020). In a pooled analysis of AZA-VEN in ND AML pts with poor risk cytogenetics the response rates were higher in TP53wt pts (CR/CRi 70%) compared with TP53mut pts (CR/CRi 41%) (Pollyea Clin Cancer Res 2022). The measurable residual disease (MRD)-negative rate was 41% in AZA-VEN treated pts in VIALE-A which was associated with improved survival (Pratz JCO 2022). Pivekimab sunirine (PVEK, IMGN632) is a first-in-class antibody-drug conjugate (ADC) comprising a high-affinity CD123 antibody, cleavable linker, and an indolinobenzodiazepine pseudodimer (IGN) payload. The novel IGN payload alkylates DNA and causes single strand breaks without crosslinking (Kovtun Blood Adv 2018). Methods This is an ongoing, open-label, multicenter, Phase 1b/2 study of PVEK in combination with AZA +VEN in adults with ND CD123-positive AML (any CD123+ expression by local flow cytometry or IHC). Pts received the recommended phase 2 dose of PVEK 0.045 mg/kg IV on D7 + AZA 75 mg/m 2 SC or IV daily on D1-7 + VEN up to 400 mg PO daily for 14 to 28 days (based on cohort assignment) in a 28-day cycle. Bone marrow assessment was performed at D14 (cohort 1) or D21 (cohort 2) of cycle 1 to determine VEN duration. The primary endpoints are composite CR rate (CCR [CR+CRh+CRp+CRi]), MRD rate (assessed centrally [Hematologics, Inc.] by flow cytometry; <0.1% defined as negative) and duration of remission. Key secondary endpoints are safety, pharmacokinetics and immunogenicity. Responses were determined using ELN 2017 criteria (with the addition of CRh) and a 14-day post-marrow count recovery window. Results As of July 17, 2023, data is available for 50 ND pts (n=25 per cohort) treated with PVEK+AZA+VEN and are aggregately reported here. The median age was 74 years (range, 46-83), 42% were ≥ 75 years old, 26% had secondary AML, 64% were ELN 2017 adverse risk, and 38% had a TP53mut. The most common non-hematologic treatment-emergent adverse events (TEAE) (all grades [grade 3+]) seen in > 20% of all pts were febrile neutropenia (44% [38%]), constipation (42% [2%]), peripheral edema (36% [4%]), diarrhea (36% [2%]), hypophosphatemia (32% [0%], nausea (28% [4%]), and hypokalemia (24% [2%]). No veno-occlusive disease (VOD) events were reported. In responders, the median time to achieve absolute neutrophil count ≥500/µL and platelet count ≥50,000/µL was 35.5 days (range, 20-55) and 22 days (range, 20-55), respectively. The median post-remission cycle delay (beyond cycle day 28) was 14 days. Two pts discontinued PVEK due to a TEAE (edema; marrow aplasia). The 60-day mortality was 4%. In the ITT population (N=50) the CR rate was 52% (26/50), and the CCR rate was 66% (33/50). In pts ≥ 75 years old, the CCR rate was 76% (16/21). In pts known to be TP53wt, both the CR and CCR rate was 88% (22/25). Additional response subsets in Table 1. Twenty-one pts received 9-14 days of VEN, 9 pts received 15-21 days of VEN and 20 pts received ≥ 22 days of VEN in cycle 1; of those who received ≤ 14 days of VEN the CR rate was 71% (15/21) and the CCR rate was 76% (16/21). Of the 26 pts who achieved CCR and had an MRD-evaluable sample, 73% (19/26) achieved MRD negativity (CCR MRD-, <0.1% residual blasts); notably all had undetectable MRD levels (lower level of detection is 0.02%). MRD-negativity was achieved rapidly with a median of 1.7 months (range, 0.8-4.5). CCR MRD- rates were high across major molecular subsets, including FLT3 (ITD/TKD) at 100% (7/7), IDH1/2 at 89% (8/9), and NPM1 at 89% (8/9), as well as ELN risk groups (intermediate 80% [8/10]; adverse 64% [9/14]). Conclusion With a manageable safety profile in pts with ND AML, the PVEK+AZA+VEN triplet demonstrated anti-leukemia activity with robust CR rates and early MRD negative responses in a cohort enriched for adverse disease characteristics (64% ELN adverse risk; 38% TP53mut). Encouraging CCR MRD- rates were observed across cytogenetic/molecular subsets, and the majority of responding pts achieved early and deep remissions, which may translate to improved clinical outcomes. The regimen was well tolerated with no new safety signals, and the addition of PVEK to the AZA-VEN backbone did not appear to meaningfully prolong count recovery.

ABSTRACT Early COVID-19 convalescent plasma (CCP) transfusion to outpatients with COVID-19 decreases progression to hospitalization, but the mechanism of how CCP reduces severity is unknown. Among 882 COVID-19 participants transfused with CCP or control plasma in a randomized controlled trial, 21 cytokines and chemokines were measured using electrochemiluminescence assays. Wilcoxon rank sum tests were used to evaluate the difference between early (transfused within 5 days of symptom onset) CCP vs early control plasma and late (transfused 6–9 days after symptom onset) CCP vs late control plasma at each visit. Linear mixed-effect models were used to assess the difference in the slope of cytokine change. Median cytokine and chemokine levels were similar between the early CCP and early control groups pre-transfusion. At the day 14 visit, only the median IL-6 ( P = 0.014) and IL-16 ( P = 0.036) levels were lower in the early CCP group compared to the early control group, but these differences were not statistically significant after correcting for multiple comparisons (requiring P < 0.0024). IL-6 levels decreased significantly faster in the early CCP group from screening to the day 14 visit compared to the early control group ( P < 0.001). No difference was observed in the slope of cytokine change from screening to day 90 between early CCP and early control groups. Late control and late CCP arms showed similar cytokine and chemokine levels through study follow-up. One mechanism by which early CCP transfusion reduces hospitalization may be by decreasing IL-6 levels, as the reduction is associated with better recovery from COVID-19. IMPORTANCE This study examined the role that cytokines may have played in the beneficial outcomes found when outpatient individuals infected with SARS-CoV-2 were transfused with COVID-19 convalescent plasma (CCP) early in their infection. We found that the pro-inflammatory cytokine IL-6 decreased significantly faster in patients treated early with CCP. Participants with COVID-19 treated with CCP later in the infection did not have the same effect. This decrease in IL-6 levels after early CCP treatment suggests a possible role of inflammation in COVID-19 progression. The evidence of IL-6 involvement brings insight into the possible mechanisms involved in CCP treatment mitigating SARS-CoV-2 severity.

Abstract Background Post-COVID conditions (PCC) are common, and risk factors include older age and female sex. While high interleukin (IL)-6 and C-reactive protein are associated with more severe disease, it is unclear whether other cytokines are associated with PCC. This study was performed to identify factors associated with PCC development. Methods The Convalescent Plasma to Limit SARS-CoV-2 Associated Complications (CSSC-004) trial was a double-blind, multi-center, randomized, controlled trial comparing the use of COVID-19 convalescent plasma (CCP) to control plasma for the prevention of hospitalization among COVID-19 outpatients. Among 882 individuals participating in the trial with available biospecimens and symptom data, the association between early COVID-19 treatment, cytokine levels and PCC was evaluated. Cytokine and chemokine levels were assessed at baseline, day 14 and day 90 using a multiplexed sandwich immuosassay. Presence of any PCC symptom was assessed at day 90. Associations between COVID-19 treatment, cytokine levels and PCC were examined using multivariate logistic regression models. Results Baseline characteristics were similar by trial treatment group (Figure 1). At day 90, 292 (33.1%) participants had PCC. The most common symptoms were fatigue (14.5%), anosmia (14.5%), and ageusia (10.0%). Levels of most cytokines decreased over time (Figure 2). Six pro-inflammatory cytokines especially IL-6 were elevated at baseline among those with PCC (Figure 3). In multivariable analysis, female sex (adjusted odds ratio [AOR]=2.70[1.93-3.81]), age 50 or greater (AOR=1.32[1.17-1.50]), and elevated baseline IL-6 (AOR=1.59[1.02-2.47]) were associated with development of PCC, whereas race, obesity, vaccine status and diabetes were not. Those who received early CCP treatment (&lt;5 days after symptom onset) compared to late CCP treatment had statistically significant lower odds of PCC (AOR=0.60 [0.38-0.95]). Conclusion This study showed high prevalence of PCC symptoms at day 90, particularly among those with higher baseline levels of IL-6 or who did not receive early CCP treatment. The potential utility of IL-6 modulation as a therapeutic intervention among individuals as higher risk for PCC should be studied. Disclosures Kelly Gebo, MD, MPH, Pfizer: Advisor/Consultant|Spark HealthCare: Advisor/Consultant Sonya L. Heath, MD, Pfizer: Data Monitoring Committee/DSMB Shmuel Shoham, MD, adagio: Advisor/Consultant|Adamis: Advisor/Consultant|ansun: Grant/Research Support|Avir Pharma: Honoraria|cidara: Grant/Research Support|F2G: Grant/Research Support|Immunome: Advisor/Consultant|Karius: Honoraria|Scynexis: Advisor/Consultant|zeteo: Grant/Research Support Judith S. Currier, M.D., MSc, Merck and Company: Advisor/Consultant|Merck and Company: Honoraria Moises A. Huaman, MD, MSc, AN2 Therapeutics Inc: Grant/Research Support|Gilead Sciences Inc: Grant/Research Support|Insmed Inc: Grant/Research Support Jay S. Raval, MD, Sanofi Genzyme: Advisor/Consultant Arturo Casadevall, MD, PhD, Ortho Diagnostics: Speakers Bureau|Sabtherapeutics: Advisor/Consultant

BACKGROUND In the gastrointestinal (GI) epithelium, enterochromaffin (EC) cells are enteroendocrine cells that use tryptophan hydroxylase 1 (TPH‐1) to produce serotonin (5‐hydroxytryptamine, 5‐HT). EC cells release 5‐HT in response chemical and mechanical stimuli. EC cell 5‐HT affects GI secretion, motility and sensation. Other neuroendocrine cells are electrically excitable, and several types use SCN3A ‐encoded voltage‐gated sodium channel Na V 1.3 for electrical excitability. It is unknown whether EC cells are electrically excitable. AIM To determine if the EC cells are electrically excitable. METHODS Murine TPH1‐CFP small bowel was dissociated, FAC sorted for TPH1‐CFP cells, and ion channel expression was analyzed by RNA‐seq. Murine TPH1‐CFP and human small bowel and colon were analyzed by immunohistochemistry (IHC). After dissociation, primary cultures from TPH1‐CFP mouse jejunum and colon were maintained for 72 hours. Scn3a expression in CFP+, CFP− cultured cells and media was analyzed by single cell polymerase chain reaction (PCR). Voltage‐ and current‐clamp experiments were performed on TPH1‐CFP cells at 24–48 hours. RESULTS RNA‐seq of FACS TPH1‐CFP EC cells from murine small bowel showed that Scn3a was the 3 rd most densely expressed ion channel gene, and no other ScnXa genes showed significant expression. Scn3a encodes a voltage‐gated sodium channel Na V 1.3. By IHC, Na V 1.3 is expressed in ~89–93% of the human and mouse small bowel and colon EC cells, which were defined as TPH1‐CFP+ for mouse and 5‐HT+ for human. Single cell PCR of CFP+ cells from primary cultures confirmed Scn3a expression. In voltage‐clamp, we found voltage‐gated fast activating and inactivating voltage‐gated currents in TPH1‐CFP EC cells from murine small bowel (78% of cells, −86±16 pA/pF, n=28), and colon (65% of cells, −66±12 pA/pF, n=14). These currents were abolished by Na + substitution by NMDG + and blocked by the Na V 1.3 inhibitor ICA‐121431 (IC 50 = 131±53 nM). Current‐clamped EC cells showed both elicited and spontaneous action potentials, also abolished by Na + substitution and Na V 1.3 block by ICA‐121431. Spontaneous current‐clamp activity showed action potential bursts of variable amplitude and frequency. CONCLUSIONS SCN3A ‐encoded voltage‐gated sodium channel Na V 1.3 is densely and specifically expressed by the EC cells of the human and mouse small and large bowel. In mouse EC cells, Na V 1.3 generates voltage‐gated sodium current which is critical for EC cell electrical excitability. Support or Funding Information NIH DK106456, DK84567, DK052766

In pathologies of the heart, blood vessels, and airways, and in cancer as well, the ultimate therapeutic target is often modulation of cellular contractile force. For discovering new therapies, drug screening technologies typically use biochemical or structural surrogates for contractile force rather than contractile force itself. Because such approaches are indirect, some hits are false while other potential hits could be missed. To fill this gap, we developed a new high‐throughput method that utilizes cellular contractile force directly as the reporter ‐‐called contractile force screening (CFS)‐‐ and established feasibility of CFS in the context of drug discovery in asthma. During an acute asthma attack, contractile forces generated by airway smooth muscle cells act to constrict the airway and thus obstruct airflow. To dilate constricted airways, asthma patients use bronchodilators to reduce these contractile forces and thus allow the airway to open more fully, but currently available bronchodilator medications often fail to relax that muscle sufficiently, especially in severe asthma. To address this unmet need for more effective bronchodilator medications, we implemented CFS to evaluate 10,000 small molecule compounds selected randomly from the Chembridge DIVERset® library. Acrylamide gels were made in 96‐well plates and fluorescent markers and collagen were coated onto gel surfaces. Upon each gel we cultured primary human airway smooth muscle (HASM) cells to near confluence. Drug effects were quantified as the ‘force response ratio’, namely, the ratio of the contractile forces before and after drug addition. By screening mixtures of 8 compounds simultaneously, we were able to evaluate 2000 compounds per week in quadruplicate. After retesting individual compounds from initially positives, we identified 2 individual compounds that relaxed HASM cells in a dose‐dependent and a non‐toxic manner. The mechanism of action is still under investigation but we found that these compounds work independent of cAMP. CFS provides a convenient, rapid, and inexpensive platform for drug discovery based upon a physiological endpoint, namely, cell contractile force. Furthermore, CFS technology has the potential to become a new high‐content assay for drug discovery in any disease process in which cellular contractile force plays a central role. Support or Funding Information NIH P50HL107171 (CADET phase I), R01EY019696 (Eye BRP), NRF GRN (NRF‐2013S1A2A2035518)

The patterns of idiopathic pulmonary fibrosis (IPF) lung disease that directly correspond to elevated hyperpolarised gas diffusion-weighted (DW) MRI metrics are currently unknown. This study aims to develop a spatial co-registration framework for a voxel-wise comparison of hyperpolarised gas DW-MRI and CALIPER quantitative CT patterns. Sixteen IPF patients underwent 3He DW-MRI and CT at baseline, and eleven patients had a 1-year follow-up DW-MRI. Six healthy volunteers underwent 129Xe DW-MRI at baseline only. Moreover, 3He DW-MRI was indirectly co-registered to CT via spatially aligned 3He ventilation and structural 1H MRI. A voxel-wise comparison of the overlapping 3He apparent diffusion coefficient (ADC) and mean acinar dimension (LmD) maps with CALIPER CT patterns was performed at baseline and after 1 year. The abnormal lung percentage classified with the LmD value, based on a healthy volunteer 129Xe LmD, and CALIPER was compared with a Bland–Altman analysis. The largest DW-MRI metrics were found in the regions classified as honeycombing, and longitudinal DW-MRI changes were observed in the baseline-classified reticular changes and ground-glass opacities regions. A mean bias of −15.3% (95% interval −56.8% to 26.2%) towards CALIPER was observed for the abnormal lung percentage. This suggests DW-MRI may detect microstructural changes in areas of the lung that are determined visibly and quantitatively normal by CT.

Abstract Histopathology is the gold standard for distinguishing tumor recurrence from treatment-induced necrosis but differentiating pseudoprogression from true recurrence is challenging in tumors with ambiguous morphological features. Prior research reported a 36% inter-rater agreement during suspected recurrence (Holdhoff et al., 2019). While serial radiographic and laboratory assessments are common, serial histopathological assessments are not. This study evaluated agreement and factors influencing assessment of active and inactive tumors through single and multiple time-point histopathological assessments. Patients who underwent initial and subsequent reoperation were identified, and their available histology slides were examined retrospectively. Four independent neuropathologists conducted two types of reviews: single time-point reviews using most recent biopsy/surgery slides, and multiple time-point reviews comparing images from initial and repeat biopsies taken 1-3 months apart. Neuropathologists completed a questionnaire assessing various tumor characteristics. Assignments were categorized as "active tumor," "treatment effect," or "unable to classify." 324 assessments were conducted (108 single time-point, 216 multiple time-point). Intraclass correlation coefficients for single vs. multiple time-point assessments were 0.72-0.93 for active tumors and 0.57-0.86 for inactive tumors. Pathologists' assessment of % inactive tumor was influenced by mitotic activity (p= 0.0028), cellularity (p&lt; 0.0001), hyalinized vessels (p= 0.0019), and necrosis (p= 0.0046). Evaluation of % active tumor was influenced by hyalinized vessels (p= 0.0006), mitotic activity (p&lt; 0.0001), cellularity (p&lt; 0.0001), and microvascular proliferation (p= 0.0093), with the latter three factors specifically affecting final sign-out pathology. Serial histopathological assessment didn’t affect determination of % active or inactive tumor. No association between % inactive tumor and fibrinoid necrosis for single time-point (p= 0.34) but a strong negative association was seen for serial assessment (p= 0.0006). Inter-rater agreement was higher for identifying active tumors than inactive tumors in both case reviews. Changes in necrosis between tissue samples in single vs. multiple timepoint assessments influenced pathologists' assessment of % inactive tumor.

Abstract H3K27M-mutant diffuse midline glioma (DMG) patients have no proven effective therapies beyond radiation. ONC201, a mitochondrial protease ClpP agonist, has recently demonstrated efficacy in these patients, but the mechanism behind this remains unknown. We assessed clinical outcomes, tumor sequencing, and tissue samples from patients treated in two completed multi-site clinical studies (n=71). Patients treated with ONC201 monotherapy following initial radiation but prior to recurrence (n=35) demonstrated a median overall survival of 21.7 months and a median progression-free survival of 12.2 months. Radiographic response was associated with increased expression of key tricarboxylic acid cycle-related genes in baseline tumor sequencing. Similar survival benefits were observed using in utero electroporation and orthotopic mouse models of H3K27M-DMG (median 107 versus 77 days [p=0.02] and median 97 versus 141 days [p=0.004], respectively). Integrated transcriptomic and metabolomic analysis of ONC201-treated H3K27M-DMG cells revealed downregulation of TCA cycle, glycolysis, and pyruvate metabolism genes, most notably oxoglutarate dehydrogenase (OGDH), and concomitant changes in levels of associated metabolites including ɑ-ketoglutarate (ɑ-KG). Interestingly, L-2-hydroxyglutarate (L-2HG), a known inhibitor of the Jumonji C domain family of histone lysine demethylases, was also increased. This corresponded with increases in repressive H3K27me3 in vitro and in human tumors accompanied by epigenetic downregulation of cell cycle regulation and neuro-glial differentiation genes. Genetic knockdown of OGDH recapitulated ONC201-mediated increases in H3K27me3. In contrast, genetic knockdown of ClpP or lactate dehydrogenase A or overexpression of L-2-hydroxyglutarate dehydrogenase (L-2HGDH), but not D-2HGDH, abrogated ONC201-mediated increases in H3K27me3, demonstrating that ONC201 induces the production of L-2HG in H3K27M-DMG cells leading to increased H3K27me3. Overall, our data demonstrates the efficacy of ONC201 in H3K27M-mutant DMG and supports ONC201 as the first monotherapy to improve outcomes in patients with H3K27M-mutant DMG for whom few therapeutic options currently exist. Mechanistically, ONC201 disrupts integrated metabolic and epigenetic pathways and reverses pathognomonic H3K27me3 reduction.

Abstract Background Implantable cardioverter defibrillators (ICDs) prevent sudden cardiac death in patients at high risk for ventricular arrhythmias, but conventional systems carry a risk of transvenous (TV) lead-related complications. The novel extravascular ICD (EV ICD) may reduce some of these complications, while offering anti-tachycardia pacing (ATP), pause prevention pacing, and a device of similar size and projected battery longevity as a TV ICD, by placing a lead substernally. The EV ICD Pivotal study demonstrated EV ICD safety and performance for termination of ventricular arrythmias at 6 months. Longer-term performance is unknown. Purpose To report the chronic safety and performance of the EV ICD system. Methods The extravascular implantable cardioverter defibrillator (EV ICD) Pivotal study was a prospective, international, single-arm, premarket clinical study. Patients with a class I or IIa indication for a single-chamber ICD per ESC or ACC/AHA/HRS guidelines were enrolled. Freedom from major system- and/or procedure-related complications at 18 mo was evaluated, as well as conversion of arrhythmias by anti-tachycardia pacing (ATP) or shock through all available follow up. Rates of ATP success were evaluated using the generalized estimating equation (GEE) and simple proportions. Results Implantation was attempted in 316 patients: 74.7% male, age 53.8±13.1 years, 82% primary prevention, left ventricular ejection fraction of 38.9%±15.4%, and New York Heart Association Class I (23.4%) or II/III (65.5%). Of 299 implanted patients (average follow up 16.2±7.2 mo), 19 experienced 80 spontaneous, appropriately treated arrhythmic episodes: 37 treated by ATP, 15 by ATP and shock, and 28 by shock alone with a Kaplan-Meier (KM) estimated 6.8% of patients experiencing appropriate therapy by 18 mo (Figure). Of discrete episodes treated with shock, 21/21 (100%) were successfully terminated. ATP was delivered in 12 patients, successfully treating 35/52 episodes (67.3%; GEE adjusted 59.0%). Inappropriate shocks occurred in 35 patients through all follow up, with a rate of 10.2% at 1 year. The KM estimate of freedom from major EV ICD system-or procedure-related complications rate through 18 mo was 91.9% (95% CI: 88.2% to 94.4%). The most common event was lead dislodgment (10 events in 9 patients) identified 0 to 120 days post-implant, predominantly due to anchoring technique. Conclusion The safety and effectiveness of a novel EV ICD system with a substernal lead extends through chronic follow up. Shocks were avoided in nearly half of all spontaneous episodes because of the availability of ATP.Figure