Pracht, Sara

Diffuse B-cell lymphomas are the most prevalent canine hematologic malignancies, and their clinical presentation resembles that of human B-cell non-Hodgkin lymphomas (NHLs). However, a lack of a clear subtyping framework perpetuates imprecise treatment approaches that fail to address mechanisms of therapy resistance. Here, we employed deep phenotyping via serial sampling and longitudinal transcriptomics to evaluate intratumoral composition and therapy response in a 6-year-old neutered male goldendoodle with stage 5A marginal zone lymphoma (MZL). Following sequential treatment consisting of a single IV dose of oncolytic vesicular stomatitis virotherapy (VSV) and standard CHOP chemotherapy 30 days later, we performed scRNAseq on seven serial lymph node biopsies and spatial sequencing on a resection taken 10 days post-VSV treatment. B cells (>90%) comprised three transcriptionally distinct and temporally stable subpopulations, with specific copy number profiles and robust spatial organization despite disrupted lymph node architecture. Analysis across subpopulations revealed downregulation of the quiescence program including KLF2, suggesting similarity to KLF2-deficient human MZL. While VSV successfully reached target B cells, downstream transcriptional responses were predominantly localized to the T-cell compartment. T cells (≤6%) showed increased proliferation and upregulation of cytotoxicity markers post-VSV administration, enriching for leukocyte-mediated cytotoxicity pathways consistent with an anti-viral immune response. Ultimately, these results provide an in vivo proof-of-concept for the treatment paradigm in canine lymphoma, while emphasizing the need for improved subtyping frameworks and multidimensional treatment strategies targeting intratumoral heterogeneity.

A three year old male neutered mixed breed dog presented with a mass on the right carpus and accompanying lameness. A Jamshidi bone biopsy was performed, and histopathology results were consistent with a sarcoma. The dog received oncolytic virotherapy (OV) with vesicular stomatitis virus (VSV) as part of a clinical trial in dogs with osteosarcoma (OSA). Ten days after VSV treatment, the affected limb was amputated, and histopathology was consistent with intramedullary HSA. Considering the new diagnosis, standard doxorubicin chemotherapy was prescribed. With this combination of therapies, the dog had an extended survival of more than seven years and remains alive at the time of writing. This is the first case report documenting OV given in conjunction with the standard of care for canine appendicular HSA.

Abstract The goal of this study was to evaluate safety, efficacy, and immunological activity of Vesicular Stomatitis Virus (VSV) expressing a species relevant (canine) interferon-beta (IFN-β) and the sodium iodide symporter (NIS), henceforth called VSV, in companion dogs with naturally occurring appendicular osteosarcoma. The hypothesis was that VSV would track to the tumor, induce oncolysis, and lead to enhanced infiltration of immune cells, expansion of virus- and tumor specific T-cell clones, and improved survival outcomes.The first 15 dogs enrolled in the VSV Immunotherapy and Genomics of Osteosarcoma Research (VIGOR) study received a single iv dose of VSV (1x109 TCID50/kg) 10 days before amputation and adjuvant carboplatin chemotherapy. The final 13 dogs were randomized in a double-blinded fashion to receive either a single dose of VSV or placebo. Outcome data were compared to those from an historical control group of 57 dogs with appendicular osteosarcoma treated between 2006 and 2018 using the standard of care of alone. VSV treatment was associated with mild systemic effects (fever and inflammation), which were self-limiting and caused no symptomatology. Alterations in the tumor microenvironment (micronecrosis, increased fibrosis, and increased inflammation) were more common and more pronounced in VSV treated dogs than in placebo-treated dogs.Reduction in the expression of co-regulated cell cycle gene clusters in tumors after VSV-treatment was observed in dogs with longer survival. Conversely, increased expression of co-regulated immune/inflammatory gene clusters was observed in both VSV-treated dogs and in placebo-treated dogs, suggesting this might be, at least partly, due to the biopsy procedures. Assessment of changes in the clonal composition of T cells within the tumors, draining lymph nodes, and systemic circulation is in progress. No differences were evident in median event-free or overall survival times among the different groups, although aspects of the study design and sample size could obscure differences. Intriguingly, a “tail” of nine dogs (41%) that were long-term survivors (>450 days) was apparent in the VSV-treated group. All but one of these long-term survivors had evidence of inflammation in the pre-treatment tumor samples or showed increased inflammation in the post-treatment samples. We conclude that neoadjuvant VSV has an excellent safety profile and provides a survival benefit for a subset of dogs with spontaneous bone cancer. Ongoing work seeks to establish distinguishing characteristics that identify those individuals most likely to benefit from this therapy, as well as to evaluate the potential to enhance this benefit through the addition of novel immunomodulatory agents as part of our efforts to translate this approach to human cancer patients. Citation Format: Kelly M. Makielski, Aaron L. Sarver, Aishwarya Sathyanarayan, Michael S. Henson, Kathleen M. Stuebner, Alexandru-Flaviu Tabaran, Ingrid Cornax, Gerard O'Sullivan, Andrea Chehadeh, Donna Groschen, Kelly Bergsrud, Lauren J. Mills, Amber L. Winter, Sara Pracht, Milcah C. Scott, Michael A. Farrar, Gary R. Cutter, Joseph S. Koopmeiners, Stephen J. Russell, Shruthi Naik, Jaime F. Modiano. Oncolytic Vesicular Stomatitis Virus expressing a species relevant interferon-beta is safe and provides a survival benefit when added as neoadjuvant to the standard of care for dogs with naturally occurring bone cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1747.