Engineered exosomes as an in situ DC-primed vaccine to boost antitumor immunity in breast cancer

Abstract

Background Dendritic cells (DCs) are central for the initiation and regulation of innate and adaptive immunity in the tumor microenvironment. As such, many kinds of DC-targeted vaccines have been developed to improve cancer immunotherapy in numerous clinical trials. Targeted delivery of antigens and adjuvants to DCs in vivo represents an important approach for the development of DC vaccines. However, nonspecific activation of systemic DCs and the preparation of optimal immunodominant tumor antigens still represent major challenges. Methods We loaded the immunogenic cell death (ICD) inducers human neutrophil elastase (ELANE) and Hiltonol (TLR3 agonist) into α-lactalbumin (α-LA)-engineered breast cancer-derived exosomes to form an in situ DC vaccine (HELA-Exos). HELA-Exos were identified by transmission electron microscopy, nanoscale flow cytometry, and Western blot analysis. The targeting, killing, and immune activation effects of HELA-Exos were evaluated in vitro. The tumor suppressor and immune-activating effects of HELA-Exos were explored in immunocompetent mice and patient-derived organoids. Results HELA-Exos possessed a profound ability to specifically induce ICD in breast cancer cells. Adequate exposure to tumor antigens and Hiltonol following HELA-Exo-induced ICD of cancer cells activated type one conventional DCs (cDC1s) in situ and cross-primed tumor-reactive CD8+ T cell responses, leading to potent tumor inhibition in a poorly immunogenic triple negative breast cancer (TNBC) mouse xenograft model and patient-derived tumor organoids. Conclusions HELA-Exos exhibit potent antitumor activity in both a mouse model and human breast cancer organoids by promoting the activation of cDC1s in situ and thus improving the subsequent tumor-reactive CD8+ T cell responses. The strategy proposed here is promising for generating an in situ DC-primed vaccine and can be extended to various types of cancers. Graphic Abstract Scheme 1. Schematic illustration of HELA-Exos as an in situ DC-primed vaccine for breast cancer. (A) Allogenic breast cancer-derived exosomes isolated from MDA-MB-231 cells were genetically engineered to overexpress α-LA and simultaneously loaded with the ICD inducers ELANE and Hiltonol (TLR3 agonist) to generate HELA-Exos. (B) Mechanism by which HELA-Exos activate DCs in situ in a mouse xenograft model ofTNBC. HELA-Exos specifically homed to the TME and induced ICD in cancer cells, which resulted in the increased release of tumor antigens, Hiltonol, and DAMPs, as well as the uptake of dying tumor cells by cDC1s. The activated cDC1s then cross-primed tumor-reactive CD8+ T cell responses. (C) HELA-Exos activated DCs in situ in the breast cancer patient PBMC-autologous tumor organoid coculture system. Abbreviations: DCs: dendritic cells; α-LA: α-lactalbumin; HELA-Exos: Hiltonol-ELANE-α-LA-engineered exosomes; ICD: immunogenic cell death; ELANE: human neutrophil elastase; TLR3: Toll-like receptor 3; TNBC: triple-negative breast cancer; TME: tumor microenvironment; DAMPs: damage-associated molecular patterns; cDC1s: type 1 conventional dendritic cells; PBMCs: peripheral blood mononuclear cells

Small extracellular vesicles: from promoting pre-metastatic niche formation to therapeutic strategies in breast cancer

“…In situ DC vaccines with tumour cell-derived sEVs as carriers activate type 1 conventional DCs (cDC1s) and cross-prime tumour-reactive CD8+ T-cell responses. A potent tumour-suppressive effect has been observed in mouse xenograft models of TNBC and patient-derived tumour organoids [ 131 ].…”

“…In situ DC vaccines with tumour cellderived sEVs as carriers activate type 1 conventional DCs (cDC1s) and cross-prime tumour-reactive CD8+ T-cell responses. A potent tumour-suppressive effect has been observed in mouse xenograft models of TNBC and patient-derived tumour organoids [131]. The sEVs of breast cancer can provide a measure of organtropism, such as specific exosomal integrin combinations (there is a link between exosomal α6β4 and α6β1 integrins and lung metastasis/exosomal αvβ5 integrin with liver metastasis/exosomal αvβ3 integrin with brain metastasis).…”

Huaier Induces Immunogenic Cell Death Via CircCLASP1/PKR/eIF2α Signaling Pathway in Triple Negative Breast Cancer

“…Due to the effective role of DCs, cell-based vaccine emerged as a promising option in tumor treatment. According to Huang et al( Huang et al, 2022 ), a in situ DC-primed vaccine drastically facilitated CD8 + T cell responses, which resulted in obvious tumor suppression in TNBC mouse xenograft model and patient-derived tumor organoids. In our study, we co-cultured BMDCs with Huaier-treated or -untreated 4T1 cells, the results revealed that TNBC cells could provoke the activation of DCs in the presents of Huaier.…”

Tumor-Derived Membrane Vesicles: A Promising Tool for Personalized Immunotherapy

“…ICD can enhance tumor antigen exposure, promote the release of immune-stimulating tumor cell content, and facilitate the uptake of dying tumor cells by DCs. Huang et al constructed a combination of TLR3 agonist Hiltonol and ICD inducer ELANE to engineer TEXs that can activate DCs in situ in a mouse xenograft model of poorly immunogenic triple-negative breast cancer and tumor organs derived from patients with hot tears; both produced effective tumor suppression [ 104 ]. In conclusion, engineered tumor-cell-derived membrane vesicles have a promising application in developing anti-tumor vaccines due to their great advantage of carrying tumor-specific antigens.…”