Intratumorally delivered formulation, INT230-6, containing potent anticancer agents induces protective T cell immunity and memory

Abstract

The benefits of anti-cancer agents extend beyond direct tumor killing. One aspect of cell death is the potential to release antigens that initiate adaptive immune responses. Here, a diffusion enhanced formulation, INT230-6, containing potent anti-cancer cytotoxic agents, was administered intratumorally into large (approx. 300mm 3) subcutaneous murine Colon26 tumors. Treatment resulted in regression from baseline in 100% of the tumors and complete response in up to 90%. CD8 + or CD8 + /CD4 + T cell double-depletion at treatment onset prevented complete responses, indicating a critical role of T cells in promoting complete tumor regression. Mice with complete response were protected from subcutaneous and intravenous re-challenge of Colon26 cells in a CD4 + /CD8 + dependent manner. Thus, immunological T cell memory was induced by INT230-6. Colon26 tumors express the endogenous retroviral protein gp70 containing the CD8 + T-cell AH-1 epitope. AH-1-specific CD8 + T cells were detected in peripheral blood of tumor-bearing mice and their frequency increased 14 days after treatment onset. AH-1-specific CD8 + T cells were also significantly enriched in tumors of untreated mice. These cells had an activated phenotype and highly expressed Programmed cell-death protein-1 (PD-1) but did not lead to tumor regression. CD8 + T cell tumor infiltrate also increased 11 days after treatment. INT230-6 synergized with checkpoint blockade, inducing a complete remission of the primary tumors and shrinking of untreated contralateral tumors, which demonstrates not only a local but also systemic immunological effect of the combined therapy. Similar T-cell dependent inhibition of tumor growth was also found in an orthotopic 4T1 breast cancer model.

Intratumoral Administration of a Novel Cytotoxic Formulation with Strong Tissue Dispersive Properties Regresses Tumor Growth and Elicits Systemic Adaptive Immunity in In Vivo Models

“…This is consistent with the hypothesis that INT230-6 enhances immune cell infiltration, possibly due to the higher number of epitopes available in the tumor, as a consequence of the localized cell death (necrosis) consistently observed. Enhanced immune cells infiltration was also observed in our recently published article [ 33 ], where CD8+ cells were observed in the tumor at different time points after treatment. INT230-6 IT and the capability of these cells in specifically killing Colon-26 cells was demonstrated in vitro.…”

“…Furthermore, the involvement of the immune cells after treatment is also supported by the inability of tumors to grow in animals having had a complete response upon re-challenge. More in depth immune infiltrating immune cell analysis on INT230-6 is reported (see Bloom [ 33 ])…”

Epithelial-to-Mesenchymal Transition Enhances Cancer Cell Sensitivity to Cytotoxic Effects of Cold Atmospheric Plasmas in Breast and Bladder Cancer Systems

“…Alternatively, higher-grade lesions and metastatic sites could potentially be treated by intratumoral injection. We have shown that direct intratumoral injection of PAM could inhibit the growth of MDA-MB-231 xenografts [64], and image-guided intratumoral injection has become an accepted delivery route for immunotherapies in melanoma and other tumor types [65,66]. This includes anti-PD1 antibody (pembrolizumab ) delivered via the DfuseRx platform [67] or EBC-46 (tigilanol tiglate) [68].…”

Altered Lipid Tumor Environment and Its Potential Effects on NKT Cell Function in Tumor Immunity

“…We can hypothesize that accumulation of tumor specific lipids in the tumor microenvironment can affect the expression of CD1d on both tumor cells and DCs, thereby suppressing their immunogenicity and facilitating eventual immune evasion. Immunogenic cell death as a result of intratumoral treatment of tumors with anti-cancer agents can lead to release of tumor-specific antigens, which then can activate T-cell mediated immunity and confer long term immunologic memory against tumor (94). The use of EPA/DHA alone or in combination with various chemotherapeutic agents has shown anti-tumor effects, mostly via apoptosis (92).…”