860 The anti-tumor activity of HSP-90 therapeutic cancer vaccine (AST-021p) combine with TLR2/3 agonist in a MMTV-neu transgenic model

BackgroundAST-021p, which is derived from HLA class II binding epitopes of human HSP90 protein, is an investigational therapeutic cancer vaccine for the malignant neoplasms. AST-021p is designed to demonstrate the immunologic efficacy by activating antigen-specific CD4+ Th1 cell in humans. Due to their ability to link the innate with the adaptive immune response, Toll-like receptor (TLR) agonists are highly promising as adjuvants in vaccines against life-threatening and complex diseases such as cancer, AIDS and malaria. In this study, AST-021p was investigated to evaluate the immunogenicity and tumor growth inhibitory effect under the condition of combining with various immune adjuvants derived from TLR agonists, using in-vivo model.MethodsThree different agonists of TLR (TLR-4, TLR-2/3, TLR-7/8) were assigned to investigate the immunogenicity in each group (4 FVB mice/group, total 4 groups). AST-021p was intradermally injected 3 times with different TLR-agonists and the immunogenicity was assessed from mouse splenocyte by HSP90-specific IFN-γ ELISpot method. We also examined the efficacy of AST-021p and selected TLR-agonist in MMTVneu Tg mice (4 mice/group, conducted twice and A total 8 mice was assigned to each group). The combination of AST-021p and TLR-2/3 agonist (AST-021p plus TLR-2/3 agonist) was injected 3 times every 10 days to mice followed by inoculated mouse mammary cancer cell line. The tumor volume change and immunogenicity were evaluated.ResultsThe most effective TLR-agonist as a potent immune adjuvant was a TLR-2/3 agonist (L-pampoTM, supplied by CHA Vaccine Institute). In MMTV-Neu transgenic mice, AST-021p (100 μg) plus TLR-2/3 agonist significantly enhanced immunogenicity by increasing up to 130±10 HSP-90 epitope specific T cells per 1x105 splenocytes (P<0.001). AST-021p plus TLR-2/3 agonist also showed higher tumor growth inhibitory effect (170±108 mm3) on post-implantation 35th day by suppressing mouse mammary cancer cell line (5x105)-derived tumor growth, compared with a TLR-2/3 agonist alone (1031±450 mm3).ConclusionsCombination regimen of AST-021p and TLR-2/3 agonist (as immune adjuvant) demonstrated significant immunogenicity and tumor prevention effect in in-vivo study. These data supported the clinical study of AST-021p combined with TLR-2/3 agonist as active immune adjuvant in certain tumor types, and phase 1/2 clinical program would be expected to be initiated.AcknowledgementsNot applicableTrial RegistrationNot applicableReferencesCsermely P, Schnaider T, Soti C, Prohaszka Z, Nardai G. The 90-kDa molecular chaperone family: structure, function, and clinical applications. A comprehensive review. Pharmacol Ther 1998;79,129–168.Wang H, Lu M, Yao M, Zhu W. Effects of treatment with an Hsp90 inhibitor in tumors based on 15 phase II clinical trials. Mol Clin Oncol 2016;5,326–334.Ramalingam S, Goss G, Rosell R. Schmid-Bindert G, Zaric B, Andric Z, Bondarenko I, Komov D, Ceric T, Khuri F. A randomized phase II study of ganetespib, a heat shock protein 90 inhibitor, in combination with docetaxel in second-line therapy of advanced non-small cell lung cancer (GALAXY-1). Ann Oncol Off J Eur Soc Med Oncol 2015,26,1741–1748.Ethics ApprovalAll experimental procedures involving mice were performed with the guidance protocols approved by the Institutional Animal Care and Use Committee of Korea University (IACUC, Approval number: KOREA-2019-129)ConsentIt is not an abstract containing sensitive or identifiable information.

Paracrine Behaviors Arbitrate Parasite-Like Interactions Between Tumor Subclones

Explaining the emergence and maintenance of intratumor heterogeneity is an important question in cancer biology. Tumor cells can generate considerable subclonal diversity, which influences tumor growth rate, treatment resistance, and metastasis, yet we know remarkably little about how cells from different subclones interact. Here, we confronted two murine mammary cancer cell lines to determine both the nature and mechanisms of subclonal cellular interactions in vitro. Surprisingly, we found that, compared to monoculture, growth of the “winner” was enhanced by the presence of the “loser” cell line, whereas growth of the latter was reduced. Mathematical modeling and laboratory assays indicated that these interactions are mediated by the production of paracrine metabolites resulting in the winner subclone effectively “farming” the loser. Our findings add a new level of complexity to the mechanisms underlying subclonal growth dynamics.

A Novel Canine Mammary Cancer Cell Line: Preliminary Identification and Utilization for Drug Screening Studies

Canine malignant mammary tumor is a dangerously fatal neoplastic disease with poor survival in female dogs. The aim of this study was to preliminary characterize a novel canine mammary cancer cell line, B-CMT, from canine primary mammary gland tumor, and to utilize it as a cell model for in vitro screening of possible therapeutic drugs. The successfully established cell line, B-CMT, was cultured over 50 passages. B-CMT has a fast proliferation rate, and a population doubling time (PDT) of 33.6 h. The B-CMT cell line lacked human epidermal growth factor receptor-2 (HER-2), estrogen receptors (ER) and progesterone receptors (PR) expression by qRT-PCR. Compared with MDCK cells, CDH1 expression of CMT cell line was significantly decreased or even absent, but GATA3 expression dramatically increased, while TGF-β expression was at a similar level. Interestingly, the B-CMT cell line from canine primary tumor also showed positive hypoxia inducible factor-1α (HIF-1α) results in immunofluorescence (IF), western blot, and qRT-PCR analysis. Ten days post inoculation with EGFP-B-CMT (B-CMT cells stably expressing EGFP), the experimental mice developed palpable soft tissue masses which histologically resembled the canine primary tumor, and was approved to be derived from B-CMT cell line through detection of EGFP by immunohistochemical (IHC) analysis. Moreover, we investigated the cytotoxicity of five drugs to B-CMT cells, and the results showed that rapamycin and imatinib significantly inhibited the proliferation of the cells in vitro within a certain range of concentration. They also induced cell cycle arrest of B-CMT cells at G1 and G2 phase, respectively. In summary, the results of this report showed that B-CMT cell line might serve as a tool for future studies on tumor microenvironment and drug resistance.

Evaluation of TFR-1 Expression in Feline Mammary Cancer and In Vitro Antitumor Efficacy Study of Doxorubicin-Loaded H-Ferritin Nanocages

The transferrin receptor 1 (TFR-1) has been found overexpressed in a broad range of solid tumors in humans and is, therefore, attracting great interest in clinical oncology for innovative targeted therapies, including nanomedicine. TFR-1 is recognized by H-Ferritin (HFn) and has been exploited to allow selective binding and drug internalization, applying an HFn nanocage loaded with doxorubicin (HFn(DOX)). In veterinary medicine, the role of TFR-1 in animal cancers remains poorly explored, and no attempts to use TFR-1 as a target for drug delivery have been conducted so far. In this study, we determined the TFR-1 expression both in feline mammary carcinomas during tumor progression, as compared to healthy tissue, and, in vitro, in a feline metastatic mammary cancer cell line. The efficacy of HFn(DOX) was compared to treatment with conventional doxorubicin in feline mammary cancer cells. Our results highlighted an increased TFR-1 expression associated with tumor metastatic progression, indicating a more aggressive behavior. Furthermore, it was demonstrated that the use of HFn(DOX) resulted in less proliferation of cells and increased apoptosis when compared to the drug alone. The results of this preliminary study suggest that the use of engineered bionanocages also offers unprecedented opportunities for selective targeted chemotherapy of solid tumors in veterinary medicine.