Citations

Abstract Background: Hemorrhagic necrotizing pancreatitis (HNP) is a highly lethal form of pancreatitis that lacks mechanism-based therapy. Intra-acinar enzyme activation is fundamental to pancreatitis initiation, yet it does not explain why only a subset of episodes progress to catastrophic hemorrhagic necrosis. Objective: To identify determinants of progression to lethal HNP and test a mechanism-based preventive intervention. Design: Using humanized trypsinogen mouse models and secretagogue regimens, we compared high-dose cerulein with low/moderate-dose cerulein and bombesin. We quantified pancreatic protease activity, performed blinded histopathologic scoring, assessed hemorrhage/vascular disruption, and evaluated enzyme localization and ductal injury by PRSS1 immunostaining. De-identified human pancreatic histology from HNP were examined. We tested a repurposed strategy using clinically approved agents for other indications: secretin to stimulate ductal fluid secretion and isosorbide mononitrate (ISMN) to promote ductal outflow via sphincter of Oddi relaxation. Results: High-dose cerulein induced robust intrapancreatic protease activation but predominantly caused edematous pancreatitis. Paradoxically, bombesin and low/moderate-dose cerulein elicited lower total pancreatic protease activity yet produced severe, frequently lethal HNP with vascular disruption and lobular ischemic necrosis. HNP was associated with intraductal enzyme accumulation and ductal injury. Secretin or ISMN alone showed limited protection, whereas combined secretin+ISMN prevented hemorrhagic necrotizing injury. Conclusion: Pancreatitis severity is determined not only by the magnitude of enzyme activation but also by where enzyme activity is exerted, implicating intraductal enzyme accumulation as a mechanistic determinant and therapeutic target in HNP. Coordinated enhancement of ductal secretion and outflow with clinically approved agents prevents HNP in vivo, supporting a translatable prevention strategy.

A liver-specific Alb-FlpO mouse line was generated. By coupling it with other existing CreERT or Cre lines, the dual recombinase approach can enable sequential gene modifications within the same cell or across various cell types in an organism for liver research through temporal and spatial gene manipulations.

Abstract Metastatic castration-resistant prostate cancer (mCRPC) is an aggressive malignancy with poor outcomes. To investigate novel therapeutic strategies, we characterized three new metastatic prostate cancer patient derived-tumor xenograft (PDTX) models and developed 3D spheroids from each to investigate molecular targeted therapy combinations including CDK4/6 inhibitors (CDK4/6i) with AKT inhibitors (ATKi). Metastatic prostate cancer tissue was collected and three PDTX models were established and characterized using whole-exome sequencing. PDTX 3D spheroids were developed from these three PDTXs to show resistance patterns and test novel molecular-targeted therapies. CDK4/6i's were combined with AKTi's to assess synergistic antitumor response to prove our hypothesis that blockade of AKT overcomes drug resistance to CDK4/6i. This combination was evaluated in PDTX three-dimensional (3D) spheroids and in vivo experiments with responses measured by tumor volumes, PSA, and Ga-68 PSMA-11 PET-CT imaging. We demonstrated CDK4/6i's with AKTi's possess synergistic antitumor activity in three mCRPC PDTX models. These models have multiple unique pathogenic and deleterious genomic alterations with resistance to single-agent CDK4/6i's. Despite this, combination therapy with AKTi's was able to overcome resistance mechanisms. The IHC and Western blot analysis confirmed on target effects, whereas tumor volume, serum PSA ELISA, and radionuclide imaging demonstrated response to therapy with statistically significant SUV differences seen with Ga-68 PSMA-11 PET-CT. These preclinical data demonstrating antitumor synergy by overcoming single-agent CDK 4/6i as well as AKTi drug resistance provide the rational for a clinical trial combining a CDK4/6i with an AKTi in patients with mCRPC whose tumor expresses wild-type retinoblastoma 1.

Abstract Background Myocarditis is an inflammation of the heart muscle most often caused by an immune response to viral infections. Sex differences in the immune response during myocarditis have been well described but upstream mechanisms in the heart that might influence sex differences in disease are not completely understood. Methods Male and female BALB/c wild type mice received an intraperitoneal injection of heart-passaged coxsackievirus B3 (CVB3) or vehicle control. Bulk-tissue RNA-sequencing was conducted to better understand sex differences in CVB3 myocarditis. We performed enrichment analysis to understand sex differences in the transcriptional landscape of myocarditis and identify candidate transcription factors that might drive sex differences in myocarditis. Results The hearts of male and female mice with myocarditis were significantly enriched for pathways related to an innate and adaptive immune response compared to uninfected controls. When comparing females to males with myocarditis, males were enriched for inflammatory pathways and gene changes that suggested worse mitochondrial transcriptional support (e.g., mitochondrial electron transport genes). In contrast, females were enriched for pathways related to mitochondrial respiration and bioenergetics, which were confirmed by higher transcript levels of master regulators of mitochondrial function including peroxisome proliferator-activated receptor gamma coactivator 1 (PGC1α), nuclear respiratory factor 1 (NRF1) and estrogen-related receptor alpha (ERRα). TRANSFAC analysis identified ERRa as a transcription factor that may mediate sex differences in mitochondrial function during myocarditis. Conclusions Master regulators of mitochondrial function were elevated in females with myocarditis compared to males and may promote sex differences in mitochondrial respiratory transcript expression during viral myocarditis resulting in less severe myocarditis in females following viral infection.

AbstractPatients with viral myocarditis are at risk of sudden death and may progress to dilated cardiomyopathy (DCM). Currently, no disease‐specific therapies exist to treat viral myocarditis. Here it is examined whether reconstituted, lyophilized extracellular vesicles (EVs) from platelets from healthy men and women reduce acute or chronic myocarditis in male mice. Human‐platelet‐derived EVs (PEV) do not cause toxicity, damage, or inflammation in naïve mice. PEV administered during the innate immune response significantly reduces myocarditis with fewer epidermal growth factor (EGF)‐like module‐containing mucin‐like hormone receptor‐like 1 (F4/80) macrophages, T cells (cluster of differentiation molecules 4 and 8, CD4 and CD8), and mast cells, and improved cardiac function. Innate immune mediators known to increase myocarditis are decreased by innate PEV treatment including Toll‐like receptor (TLR)4 and complement. PEV also significantly reduces perivascular fibrosis and remodeling including interleukin 1 beta (IL‐1β), transforming growth factor‐beta 1, matrix metalloproteinase, collagen genes, and mast cell degranulation. PEV given at days 7–9 after infection reduces myocarditis and improves cardiac function. MicroRNA (miR) sequencing reveals that PEV contains miRs that decrease viral replication, TLR4 signaling, and T‐cell activation. These data show that EVs from the platelets of healthy individuals can significantly reduce myocarditis and improve cardiac function.

Abstract Recent studies demonstrate that mitochondrially-generated reactive oxygen species (ROS) downstream of oncogenic KRAS drive acinar-to-ductal metaplasia (ADM), a key first step in the pancreatic ductal adenocarcinoma (PDA) progression model. MnSOD/SOD2 is a mitochondrial enzyme that converts superoxide into hydrogen peroxide. Previous studies have shown that SOD2 is biologically relevant to the study of pancreatic cancer. Some patients with a SOD2 polymorphism resulting in less active MnSOD at the mitochondrial matrix are at increased risk of developing pancreatic cancer. Additionally, MnSOD is lost in high-grade human PanIN, further suggesting a role in tumor development. To elucidate the role of MnSOD in pancreatic cancer initiation and progression, we crossed Sod2lox/lox mice into the p48Cre;LSL-KrasG12D (KC) mouse model. We found increased ROS, abundantly more abnormal tissue development and presence of flat lesions indicating accelerated early progression. However, Kaplan Meyer survival analysis of KC and KC;Sod2−/− mice did not indicate faster progression to cancer, suggesting that for later steps additional signaling is needed. In summary, we identify MnSOD as a key antioxidant molecule preventing initiation of PDA. Citation Format: Alicia K. Fleming Martinez, Brandy H. Edenfield, Irene Esposito, Peter Storz. Knockout of Sod2 accelerates KrasG12D-driven formation of pancreatic cancerous lesions. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4775.

Abstract MT-5111 is a 55kD engineered toxin body targeting HER2 in solid tumors that binds to an epitope distinct from trastuzumab and pertuzumab, offering potential combination strategies with other HER2-targeting agents. MT-5111 works by internalizing, self-routing through intracellular compartments to the cytosol, and inducing potent cell-kill via the enzymatic and permanent inactivation of ribosomes. This is a phase 1 study in adults with advanced HER2+ solid tumors. MT-5111 is dosed weekly IV over 30 min in every 21-day cycle until disease progression, unacceptable toxicity, death, or withdrawn consent. The study has dose escalation (Part A) cohorts enrolling patients (pts) with any HER2+ cancer (CA) and expansion (Part B) cohorts for HER2+ breast cancer (BC), Gastric or Gastroesophageal junction adenocarcinoma (GEA), or other HER2+ solid CA. As of 30 June 2022, 42 total pts had enrolled (36 in Part A on 0.5-23 µg/kg/dose, 6 pts with BC in Part B1 on 10 µg/kg/dose). Median age 65 years, 28 (66.78%) pts were female, median of 4 prior systemic and 2 prior HER2-targeting treatment (tx). 17 pts with BC, 6 with biliary CA, 9 with GEA, and 10 with other solid CA have enrolled. Of the 17 BC pts, 15 received ≥ 10 µg/kg/dose. Tx emergent adverse events (TEAEs) have been reported in 40 (95%) pts, and tx-related AEs (TRAE) occurred in 23 (55%) pts. No pt experienced G4-G5 TRAE. G1 troponin elevations were noted in 5 pts without clinical signs of cardiotoxicity (1 pt 6.75 µg/kg, 2 pts 10 µg/kg, 1 pt 17 µg/kg, 1 pt 23 µg/kg). Reversible G1/G2 infusion-related reactions were reported in 2 pts. Tx-related G1-G3 rash was observed in 5 pts (4 pts ≥ 10 µg/kg/dose); maculopapular in 2 pts, acneiform in 1 pt and associated with pruritus in 3 pts. The G3 rash developed one wk after first dose of 23 µg/kg, was declared a DLT, improved with systemic steroid therapy and the pt continued tx at the same dose without recurrence. Best overall response per RECIST thus far is stable disease (SD) in 17 pts, non-CR/non-PD in 1 pt, and progressive disease (PD) in 14 pts. 1 pt had non-CR/non-PD for 30 wks (1 μg/kg, BC); 1 pt had SD for 24wks (10 μg/kg, pancreatic); 1 pt is on tx with SD through 8 cycles (10 μg/kg, BC). Of the 10 BC pts who received ≥ 10 μg/kg/dose, the best response was 5 SD. The mean serum concentration of MT-5111 has increased in a dose-proportional manner starting at 6.75µg/kg/dose (Table 1). The soluble HER2 (sHER2) levels at end of tx were higher compared to baseline in cohorts that received ≤ 4.5µg/kg/dose, but similar or lower in cohorts that received ≥ 6.75µg/kg/dose. Higher MT-5111 doses have been well tolerated and may saturate circulating sHER2, leading to more predictable serum concentrations and tumor penetration. The Cmax in humans at doses ≥6.75 µg/kg/dose is above the in vitro IC50 for high HER2+ cell lines (0.029nM) and at 17 µg/kg/dose, above the IC50 for moderate HER2+ cells (1.6nM). In conclusion, the dose proportionate increase in serum concentration with levels above the in vitro IC50 and the leveling off/reduction of sHER2 indicate exposure to MT-5111 is at clinically therapeutic levels. Skin toxicity at higher doses may indicate on-target effect as observed in other EGFR-targeted therapies where it is associated with clinical response and a better prognosis. sHER2 biomarker data is expected for all cohorts with PK correlation and 23µg/kg safety and efficacy data. PK profile of MT-5111, C1D1 values Citation Format: Meena Okera, Brian A. Van Tine, Joleen M. Hubbard, Minal Barve, Erika Hamilton, Monica M. Mita, Frances Valdes-Albini, Daniel Ahn, Admasu Mamuye, Joshua Pelham, Amy Yuet, Diana Yurewicz, Yanning Liu, Andres Machado Sandri, William J. Edenfield, Aki Morikawa, William Gradishar, Rajiv Kumar, Zev A. Wainberg. A phase 1 study of the novel immunotoxin MT-5111 in patients with HER2+ tumors: interim results [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT2-11-01.

As survival in breast cancer patients from newer therapies increases, concerns for chemotherapy-induced cardiotoxicity (CIC) have offset some of these benefits, manifesting as a decline in left ventricular ejection fraction (LVEF). Patients receiving anthracycline-based chemotherapy followed by trastuzumab are at risk for CIC. Previous research evaluating whether clinical biomarkers predict cardiotoxicity has been inconsistent. Recently, angiotensin II type 1 receptor (ATR1) and endothelin 1 (ET1) have been shown to play a role in breast tumor growth. We evaluated ATR1 and ET1 expression in breast cancer tissue and its association with CIC. A total of 33 paraffin-embedded breast tissue specimens from women with breast cancer treated with anthracycline-based chemotherapy and trastuzumab were analyzed by immunohistochemistry (IHC) and qRT-PCR. We found that ET1 expression was increased in patients with an LVEF ≤ 50% (p = 0.032) with a lower LVEF correlating with higher ET1 expression (r = 0.377, p = 0.031). In patients with a change in LVEF of greater than 10%, greater ET1 expression was noted compared to those without a change in LVEF (p = 0.017). Increased ET1 expression in breast tumor tissue is associated with reduced LVEF. Future studies need to examine whether ET1 may be a tissue biomarker that helps predict the risk of developing CIC in women with breast cancer.