Syngeneic Syrian hamster tumors feature tumor-infiltrating lymphocytes allowing adoptive cell therapy enhanced by oncolytic adenovirus in a replication permissive setting

Abstract

Adoptive transfer of tumor-infiltrating lymphocytes (TIL) has shown promising yet sometimes suboptimal results in clinical trials for advanced cancer, underscoring the need for approaches improving efficacy and safety. Six implantable syngeneic tumor cell lines of the Syrian hamster were used to initiate TIL cultures. TIL generated from tumor fragments cultured in human interleukin-2 (IL-2) for 10 d were adoptively transferred into tumorbearing hamsters with concomitant intratumoral injections of oncolytic adenovirus (Ad5-D24) for the assessment of antitumor efficacy. Pancreatic cancer (HapT1) and melanoma (RPMI 1846) TIL exhibited potent and tumor-specific cytotoxicity in effector-to-target (E/T) assays. MHC Class I blocking abrogated the cell killing of RPMI 1846 TIL, indicating cytotoxic CD8 C T-cell activity. When TIL were combined with Ad5-D24 in vitro, HapT1 tumor cell killing was significantly enhanced over single agents. In vivo, the intratumoral administration of HapT1 TIL and Ad5-D24 resulted in improved tumor growth control compared with either treatment alone. Additionally, splenocytes derived from animals treated with the combination of Ad5-D24 and TIL killed autologous tumor cells more efficiently than monotherapy-derived splenocytes, suggesting that systemic antitumor immunity was induced. For the first time, TIL of the Syrian hamster have been cultured, characterized and used therapeutically together with oncolytic adenovirus for enhancing the efficacy of TIL therapy. Our results support human translation of oncolytic adenovirus as an enabling technology for adoptive T-cell therapy of solid tumors.

Oncolytic Adenoviruses Armed with Tumor Necrosis Factor Alpha and Interleukin-2 Enable Successful Adoptive Cell Therapy

“…Conveniently, human IL-2 38 and human TNF-α are also bioactive in hamsters, which is evident from the hamster experiment where the unarmed virus had only moderate antitumor effects as compared with the human cytokine-coding viruses that share the same backbone construct. Furthermore, we have developed a method to extract and expand TILs from established hamster tumors, despite the limited availability of hamster-specific reagents 39 . Unfortunately, specific expansion of, for example, CD8 + T cells is unfeasible and the TIL pool depends on the population present in the tumor at the time of collection.…”

“…IL-2 induces both regulatory and helper T cells; 40 however, in this study, the nature of CD4 + cells could not be specified. Interestingly, the observed upregulation of MHC II (a marker for antigen-presenting cells) might indicate that the combination of both cytokines enables efficient tumor recognition by cytotoxic CD4 + T cells,39, 41 thus contributing to the overall efficacy. In addition, the presence of TNF-α stimulates the expression of IL-6, a cytokine needed for helper T cell differentiation 40, 42.…”

“…CD8b + , CD4 + , and MHC class II + cells were detected from hamster tumors, spleens, and lymph nodes as described by Siurala et al 39 . Polyclonal anti-Asialo-GM1 AF488 antibody (eBioscience) was used for detecting natural killer cells and a subset of monocytes/macrophages (0.5 μg per reaction) and anti-human/mouse Galectin-3 (Mac-2) PE (eBioscience) for detecting macrophages and dendritic cells (0.2 μg per reaction).…”

Adenovirus Coding for Interleukin-2 and Tumor Necrosis Factor Alpha Replaces Lymphodepleting Chemotherapy in Adoptive T Cell Therapy

“…28,29 We have shown that IL-2 and TNF-a can recruit natural killers and T cells to the tumor when produced from oncolytic adenoviruses. [19][20][21]23,30,31 This effect on trafficking could explain part of the good efficacy seen here. Additionally, preclinical work has proposed that host lymphodepletion associated the increased proliferation of CD8+ T cells with high antitumor efficacy in lymphodepleted hosts.…”

Modeling the Efficacy of Oncolytic Adenoviruses In Vitro and In Vivo: Current and Future Perspectives

“…Both of these in vivo models are immunocompetent and involve respective syngeneic tumor cell lines allowing for human OAds to study their lytic effects, distributions, and generated immune responses as well as toxicities [75,76]. Recently, combination of OAd5∆24 and infusion of ex vivo expanded tumor infiltrating lymphocytes induced systemic anti-tumor immunity in the Syrian hamster model [77]. Another study confirmed that T cells mediated anti-tumor activity in syrian hamsters and prior immunization with OAd resulted in clearance of the virus from tumors.…”