Effective Combination Immunotherapy with Oncolytic Adenovirus and Anti-PD-1 for Treatment of Human and Murine Ovarian Cancers

SIMPLE SUMMARY: This study was conducted to find a new, more efficient, treatment for ovarian cancer. A combination of an oncolytic adenovirus (TILT-123) with immune checkpoint inhibitors was employed to treat ex vivo patient samples and was found statistically significantly more effective than control treatments ex vivo and showed potent efficacy towards in vivo tumor growth. ABSTRACT: Ovarian cancer (OvCa) is one of the most common gynecological cancers and has the highest mortality in this category. Tumors are often detected late, and unfortunately over 70% of OvCa patients experience relapse after first-line treatments. OvCa has shown low response rates to immune checkpoint inhibitor (ICI) treatments, thus leaving room for improvement. We have shown that oncolytic adenoviral therapy with Ad5/3-E2F-d24-hTNFa-IRES-hIL2 (aka. TILT-123) is promising for single-agent treatment of cancer, but also for sensitizing tumors for T-cell dependent immunotherapy approaches, such as ICI treatments. Therefore, this study set out to determine the effect of inhibition of the immune checkpoint inhibitors (ICI), in the context of TILT-123 therapy of OvCa. We show that simultaneous treatment of patient derived samples with TILT-123 and ICIs anti-PD-1 or anti-PD-L1 efficiently reduced overall viability. The combinations induced T cell activation, T cells expressed activation markers more often, and the treatment caused positive microenvironment changes, measured by flow cytometric assays. Furthermore, in an immunocompetent in vivo C57BL/6NHsda mouse model, tumor growth was hindered, when treated with TILT-123, ICI or both. Taken together, this study provides a rationale for using TILT-123 virotherapy in combination with TILT-123 and immune checkpoint inhibitors together in an ovarian cancer OvCa clinical trial.