Abstract 4473: Evaluation of the potential of oncolytic vaccinia virus delivered by autologous SVF to modulate innate and adaptive immunity in patients with diverse solid and hematological malignancies
Authors: Draganov Dobrin , Santidrian Antonio , Minev Ivelina , Nguyen Duong , Zamarin Dmitriy , Marincola Francesco , Butterfield Lisa , Minev Boris 
Published: September 2020

The development of oncolytic viruses for the treatment of cancer has been significantly hampered by their rapid clearance in circulation due to complement and antibody-mediated neutralization. In our recent first-in-human Phase I clinical trial, we confirmed the safety and feasibility of our approach to enhance virus delivery and improve tumor targeting by utilizing an autologous stromal vascular fraction (SVF) based cell delivery system. Patient sample analysis demonstrated that patients could be stratified based on the level of vaccinia virus amplification in vivo, as evidenced by analysis of persistent viral DNA in the blood.

In the current study, we evaluated the immunomodulatory potential of vaccinia virus delivered by autologous stromal vascular fraction (SVF)-derived cells and attempted to identify immunological correlates of successful vaccinia virus amplification in vivo. To this end, we performed an extensive time-course analysis of cytokines in patients' plasma as well as various peripheral blood immune subpopulations using Luminex multi-analyte profiling and multiparameter flow cytometry, respectively. We also analyzed the impact of this therapeutic approach on the innate and adaptive immune subpopulations, including NK cells, myeloid cells, as well as effector, regulatory and memory T cells.

Therapy with SFV-delivered oncolytic vaccinia virus induced a coordinated activation of cytokine, T cell and NK responses in patients as early as 1 day after treatment, which peaked around 1-week and lasted for up to 1-month post treatment. The ability of the oncolytic virus to effectively amplify in cancer patients correlated with significant changes of multiple innate (NK) and adaptive (T cell) immunological parameters. Interestingly, patient stratification into groups with transient versus persistent viral DNA was linked to opposing and mutually exclusive patterns of robust activation of NK versus T cell responses, respectively.

Overall, this study establishes the timeline of treatment-related immunological changes and identifies potential immunological correlates associated with the persistence of virus amplification in vivo. Therefore, our findings provide new insights into the role of interpatient immunological variability and will contribute to the proper evaluation of the therapeutic potency of oncolytic virotherapy in future clinical trials.

Citation Format: Dobrin Draganov, Antonio Santidrian, Ivelina Minev, Duong Nguyen, Dmitriy Zamarin, Francesco Marincola, Lisa Butterfield, Boris Minev. Evaluation of the potential of oncolytic vaccinia virus delivered by autologous SVF to modulate innate and adaptive immunity in patients with diverse solid and hematological malignancies [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4473.