Dr. Sita Withers
Assistant Professor
Veterinary Clinical Sciences (VCS)

After graduating with a veterinary degree from the University of Melbourne Australia in 2008, Sita practiced in a mixed animal clinic in Far North Queensland for a year. She then returned to Melbourne to pursue a small animal internship, and subsequently moved to California to undertake a medical oncology residency at UC Davis. During her residency she developed a keen interest in cancer research, which prompted her pursuit of a PhD after becoming board certified in veterinary medical oncology. Her PhD in Integrative Pathobiology enabled her to develop skills in pathology, immunology, and flow cytometry. The focus of her research is to investigate the immune microenvironment in canine and human osteosarcoma, and to facilitate the translation of bench-top findings into clinical advancements for osteosarcoma patients of both species.

Teaching Interests:
Clinical instruction; Communication

Research Interests:
Comparative cancer immunology; Tumor microenvironment; Metastasis

 Awards & Honors:
  • 2021 Dean's Teacher Merit Honor Roll- DVM Year II & IV
  • 2020 Dean's Teacher Merit Honor Roll- DVM Year I & IV
  • 2008 Graduated with honours
  • PhD University of California- Davis
  • BVSc University of Melbourne
  • Center for Preclinical Disease Research Project 1- "Strategic inhibition of EGFR-family signaling using novel peptidomimetic inhibitors of HER-2 for the treatment of osteosarcoma", NIH COBRE, $669,105.00
  • Center for Pre-Clinical Disease Research , National Institutes of Health - NIH, $11,192,691.00
  • Repurposing drugs to modulate myeloid-derived suppressor cells (MDSCs) in canine soft tissue sarcomas, American Kennel Club- Canine Health Foundation, $13,782.00
  • Exploring abscopal effects in canine nasal tumors via fine needle aspirate of draining lymph nodes, VCS CORP, $3,950.00
  • Uncovering the ability of chemotherapy-resistant canine osteosarcoma cells to modulate the immune microenvironment via IL-34 production , VCS CORP, $3,998.00
  • Center for Translational Viral Oncology Pilot- "Utilization of naturally-occurring canine osteosarcoma to develop virus-based combination immunotherapy strategies that exploit defects in STING signaling", NIH COBRE, $58,399.00
  • Prospective evaluation of the effect of vincristine alone on tumor burden and circulating myeloid-derived suppressor cells (MDSCs) in dogs with naïve high-grade multicentric lymphoma, VCS CORP, $4,000.00
  • Verification of phenotypic markers identifying T-lymphocyte memory subsets in dogs, VCS CORP, $4,000.00
  • Characterizing The Effects of STING Deficiency in Osteosarcoma Cells on DNA Damage-Induced Inflammation , SVM CORP, $10,000.00
  • Design, synthesis and evaluation of grafted peptides/peptidomimetics for the inhibition of protein-protein interactions of EGFRs in osteosarcoma. , Louisiana Biomedical Research Network- Graduate student summer research program, $8,000.00
  • Effects of polarized canine macrophage on osteosarcoma cells, Louisiana Biomedical Research Network- Undergraduate summer research scholar, $5,000.00
  • STING expression in osteosarcoma, Louisiana Biomedical Research Network- Undergraduate summer research scholar, $5,000.00
Journal Article, Academic Journal:
  • A grafted peptidomimetic for EGFR heterodimerization inhibition: Implications in NSCLC models., Singh, S; Mattheolabakis, G; Gu, X; Withers, Sita; Dahal, A; Jois, S, 2021, European journal of medicinal chemistry , Volume: 216, Pages: 113312
  • What is your diagnosis? Uveitis in a Parakeet, Cummings, Charles; Tully, Thomas; Stohr, Anke; Pence, Leslie; Nelson, Courtney; Withers, Sita; Carter, Renee, 2020, Journal of Avian Medicine and Surgery
  • Development of canine PD-1/PD-L1 specific monoclonal antibodies and amplification of canine T cell function., Choi, J; Withers, Sita; Chang, H; Spanier, J; De La Trinidad, V; Panesar, H; Fife, B; Sciammas, R; Sparger, E; Moore, P; Kent, M; Rebhun, R; McSorley, S, 2020, PloS one , Volume: 15, Number: 7, Pages: e0235518
  • Metastatic immune infiltrates correlate with those of the primary tumour in canine osteosarcoma., Withers, Sita; York, D; Choi, J; Woolard, K; Laufer-Amorim, R; Sparger, E; Burton, J; McSorley, S; Monjazeb, A; Murphy, W; Canter, R; Rebhun, R, 2019, Veterinary and comparative oncology , Volume: 17, Number: 3, Pages: 242-252
  • Association of macrophage and lymphocyte infiltration with outcome in canine osteosarcoma., Withers, Sita; Skorupski, K; York, D; Choi, J; Woolard, K; Laufer-Amorim, R; Sparger, E; Rodriguez, C; McSorley, S; Monjazeb, A; Murphy, W; Canter, R; Rebhun, R, 2019, Veterinary and comparative oncology , Volume: 17, Number: 1, Pages: 49-60
  • Paradoxical effects of obesity on T cell function during tumor progression and PD-1 checkpoint blockade., Wang, Z; Aguilar, E; Luna, J; Dunai, C; Khuat, L; Le , C; Mirsoian, A; Minnar, C; Stoffel, K; Sturgill, I; Grossenbacher, S; Withers, Sita; Rebhun, R; Hartigan-O'Connor, D; Méndez-Lagares, G; Tarantal, A; Isseroff, R; Griffith, T; Schalper, K; Merleev, A; Saha, A; Maverakis, E; Kelly, K; Aljumaily, R; Ibrahimi, S; Mukherjee, S; Machiorlatti, M; Vesely, S; Longo, D; Blazar, B; Canter, R; Murphy, W; Monjazeb, A, 2019, Nature medicine , Volume: 25, Number: 1, Pages: 141-151
  • In vitro and in vivo activity of liposome-encapsulated curcumin for naturally occurring canine cancers., Withers, Sita; York, D; Johnson, E; Al-Nadaf, S; Skorupski, K; Rodriguez, Jr, C; Burton, J; Guerrero, T; Sein, K; Wittenburg, L; Rebhun, R, 2018, Veterinary and comparative oncology , Volume: 16, Number: 4, Pages: 571-579
  • Multi-color flow cytometry for evaluating age-related changes in memory lymphocyte subsets in dogs., Withers, Sita; Moore, P; Chang, H; Choi, J; McSorley, S; Kent, M; Monjazeb, A; Canter, R; Murphy, W; Sparger, E; Rebhun, R, 2018, Developmental and comparative immunology , Volume: 87, Pages: 64-74
  • Enrofloxacin enhances the effects of chemotherapy in canine osteosarcoma cells with mutant and wild-type p53., York, D; Withers, Sita; Watson, K; Seo, K; Rebhun, R, 2017, Veterinary and comparative oncology , Volume: 15, Number: 3, Pages: 1087-1100
  • Evaluation of optimal water fluoridation on the incidence and skeletal distribution of naturally arising osteosarcoma in pet dogs., Rebhun, R; Kass, P; Kent, M; Watson, K; Withers, Sita; King, A, 2017, Veterinary and comparative oncology , Volume: 15, Number: 2, Pages: 441-449
  • Management of an invasive and metastatic Sertoli cell tumor with associated myelotoxicosis in a dog., Withers, Sita; Lawson, C; Burton, A; Rebhun, R; Steffey, M, 2016, The Canadian veterinary journal = La revue veterinaire canadienne , Volume: 57, Number: 3, Pages: 299-304
  • Paraneoplastic hypertrophic osteopathy in 30 dogs., Withers, Sita; Johnson, E; Culp, W; Rodriguez, Jr, C; Skorupski, K; Rebhun, R, 2015, Veterinary and comparative oncology , Volume: 13, Number: 3, Pages: 157-65
  • BMI1 is expressed in canine osteosarcoma and contributes to cell growth and chemotherapy resistance., Shahi, M; York, D; Gandour-Edwards, R; Withers, Sita; Holt, R; Rebhun, R, 2015, PloS one , Volume: 10, Number: 6, Pages: e0131006
  • Fasting Reduces the Incidence of Delayed-Type Vomiting Associated with Doxorubicin Treatment in Dogs with Lymphoma., Withers, Sita; Kass, P; Rodriguez, Jr, C; Skorupski, K; O'Brien, D; Guerrero, T; Sein, K; Rebhun, R, 2014, Translational oncology
  • Evaluation of a single subcutaneous infusion of carboplatin as adjuvant chemotherapy for dogs with osteosarcoma: 17 cases (2006-2010)., Simcock, J; Withers, Sita; Prpich, C; Kuntz, C; Rutland, B, 2012, Journal of the American Veterinary Medical Association , Volume: 241, Number: 5, Pages: 608-14
  • Utilizing microbes to treat naturally-occurring cancer in veterinary species, Withers, Sita; Sparger, Elizabeth; Boudreaux, Bonnie; Mason, Nicola, 2019
  • Canine cancer immunotherapy studies: linking mouse and human., Park, J; Withers, Sita; Modiano, J; Kent, M; Chen, M; Luna, J; Sparger, E; Rebhun, R; Monjazeb, A; Murphy, W; Canter, R, 2016