No abstract

IFEE lesions represented an accumulation of leucocytes in submucosa and muscularis, with dominance of eosinophils and macrophages and smaller numbers of lymphocytes, plasma cells and neutrophils. T cells represented the dominant lymphocytes. The mucosa overlying the lesion and both mucosa and submucosa in IFEE nonlesion sites and in DEE exhibited a similar composition, with different prevalence of various cell types. Macrophages were significantly more prevalent in the mucosal and submucosal infiltrates in IFEE nonlesion sites than in DEE, and lymphocytes significantly more prevalent in the mucosa in DEE than in IFEE nonlesion sites. The findings confirm IFEE as a primary eosinophilic intestinal disorder and indicate that IFEE represents a focally exacerbated inflammatory reaction in horses with DEE, possibly due to functional changes in the macrophage and T cell components, with subsequent excessive recruitment of both eosinophils and macrophages.

Surgical implantation of radiotelemetric transmitters is a current practice to collect a variety of physiological parameters in unrestrained laboratory animals, and in rodents in particular. In this study, the incidence of peritoneal sarcomatosis arising secondary to surgically implanted telemetry devices (< 15% of implanted Sprague Dawley rats) is considered to represent a significant issue for both animal welfare and data validity in affected animals. Macroscopically, the telemetry-associated fibrosarcomas spread along the visceral and parietal peritoneum and mesentery surrounding abdominal organs. The histologic morphology of these sarcomas was typically an undifferentiated sarcoma, although well-differentiated fibrosarcomas and telangiectatic and pleomorphic variants were noted. Using special stains such as Masson's Trichrome demonstrated a collagenous extracellular matrix in 50% of these rats, which is consistent with a fibroblastic origin. Immunohistochemical studies clearly delineated the mesenchymal components of the sarcomas (fibroblasts and smooth muscle cells); one case, however, was diagnosed as an osteosarcoma.

Permanent vascular catheterization for intravascular access is one of the most commonly applied techniques used on rodents in pharmacology studies. However, use of the intravascular catheters is complicated by nontolerance due to thromboembolic disease and sepsis. We have undertaken an extensive pathologic and clinical analysis of an intravascular catheterization model in Wistar Han and Sprague-Dawley rats, with a particular focus on carotid artery catheterization with or without jugular vein catheterization, in order to define the pathologic mechanisms behind nontolerance and define clinical end points to ensure maximal animal welfare. Further, we have explored various potential solutions to increase the tolerance of the procedure. In these studies, indwelling catheters were found to cause a high degree of thromboembolic disease with infarction in the brain, cecal tip, and kidneys being the primary causes of nontolerance. Loss of greater than 10% body weight was determined to be the most sensitive indicator of nontolerance and was closely correlated with degree of renal parenchymal loss. Sepsis was noted as a very rare complication, indicating that routine aseptic surgical techniques are adequate for preventing this complication.

Chronic prostatitis characterized on light microscopic examination by moderate, multifocal, predominantly lymphocytic inflammation associated with epithelial atypia and intranuclear and cytoplasmic inclusion-like material was identified in the prostate gland of 2 Wistar Han rats administered an immunomodulatory test article in a 6-month chronic toxicity study. Transmission electron microscopy of the prostate glands identified 45-nm, nonenveloped, icosahedral virions arranged in paracrystalline array within the cell nuclei in 1 of the 2 rats. The size, shape, location, and array pattern were most consistent with a polyomavirus. The light and electron microscopic findings after immunosuppression in our case have a resemblance to a polyomavirus recently reported to affect prostate gland epithelium in a colony of immunocompromised X-linked severe combined immune deficiency rats. To the best of our knowledge, this is the first report of light and electronic microscopic lesions in the reproductive tract associated with polyomavirus following chronic immunosuppression in a widely used, wild-type Wistar Han rat.

Anti-CD19 CAR T cell therapies have improved outcomes for non-Hodgkin lymphoma (NHL) patients. However, only 30-40% of patients treated with commercially available CART cell therapies obtain long term remission, highlighting the need for more efficacious and durable therapies. Emerging clinical data suggest several failure modes for CD19 CAR T cell therapies: including loss or downregulation of CD19 antigen, loss of co-stimulation pathways on tumor cells, exhaustion of CAR-T cells, and immunosuppressive microenvironments. To overcome these hurdles, we devised the next-generation autologous CAR-T cell therapy bbT369. bbT369 is dual targeted (CD79a/CD20) CAR T cell therapy that uses an OR gate design to limit antigen escape, has split 41BB and CD28 co-stimulatory domain architecture to augment T cell activation, and contains a knock-out of the CBLB gene to enhance potency and reduce T cell exhaustion. Here we report the first results with bbT369, demonstrating anti-lymphoma activity in in vitro assays and in vivo using xenograft mouse models. We demonstrate that CD79a and CD20 expression is B cell lineage restricted in normal human tissue and confirm that these proteins are co-expressed in diffuse large B cell samples. To target these antigens, we show a split dual-targeting CAR configuration is optimal for bbT369-directed tumor cell killing. Using an engineered megaTAL, we demonstrate high on-target activity of greater than 75% insertions and deletions (Indels) at the CBLB target site using clinical-scale manufacturing processes and low off-target activity (all off-targets less than 0.2%). In in vitro tumor co-culture assays, we show that inclusion of the CBLB gene edit in bbT369 increases Interleukin (IL)-2 production relative to an unedited anti-CD79a/CD20 CAR T cell control. Using various xenograft mouse models, we showed that bbT369 has similar or improved efficacy compared to anti-CD19 CAR drug product, including in low tumor-antigen models. In the Toledo subcutaneous xenograft model, bbT369 showed a 3-fold increase in T cell expansion compared with an unedited anti-CD79a/CD20 dual-targeting CAR T cell control. Furthermore, while a fraction of mice (3/5) receiving the unedited anti-CD79a/CD20 dual-targeting CAR T cells experienced late relapses (between 60-80 days following initial tumor clearance), all mice (n=5) receiving bbT369 were fully protected from late relapses (up to day 104 of follow-up). Collectively, the data support a first-in-human trial for bbT369 to evaluate initial safety and efficacy in NHL patients. Citation Format: Michael Certo, Christopher Baldeviano, Sharlene Adams, Martin Asimis, Alexander Astrakhan, Andy Chavkin, Maria L. Cabral, Jimmy Chu, Marie Debrue, Devina Desai, John Evans, Pinky Htun, Amanda Iniguez, Jordan Jarjour, Carl Johnson, Harini Kantamneni, Sema Kurtulus, Michael Magee, Unja Martin, Seamus McKenney, Sara Miller, Prashant Nambiar, Vinh Khang Nguyen, Mauris Nnamani, Jen Obrigewitch, Lisa Pechilis, Molly Perkins, Christopher Petersen, Jason Pinger, Cindy Rogers, Nick Rouillard, Kendal Sanson, Emily Thompson, Collin Walter, Roslyn Yi, Sarah Voytek, Philip Gregory. bbT369, a dual-targeted and CBLB gene-edited autologous CART product, demonstrates anti-lymphoma activity in preclinical mouse models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 581.