Antibody-Peptide Epitope Conjugates for Personalized Cancer Therapy

Abstract

Antibody–peptide epitope conjugates (APEC) are a new class of modified antibody–drug conjugates that redirect T-cell viral immunity against tumor cells. APECs contain a tumor-specific protease cleavage site linked to a patient-specific viral epitope, resulting in presentation of viral epitopes on cancer cells and subsequent recruitment and killing by CD8+ T cells. Here we developed an experimental pipeline to create patient-specific APECs and identified new preclinical therapies for ovarian carcinoma. Using functional assessment of viral peptide antigen responses to common viruses like cytomegalovirus (CMV) in patients with ovarian cancer, a library of 192 APECs with distinct protease cleavage sequences was created using the anti-epithelial cell adhesion molecule (EpCAM) antibody. Each APEC was tested for in vitro cancer cell killing, and top candidates were screened for killing xenograft tumors grown in zebrafish and mice. These preclinical modeling studies identified EpCAM-MMP7-CMV APEC (EpCAM-MC) as a potential new immunotherapy for ovarian carcinoma. Importantly, EpCAM-MC also demonstrated robust T-cell responses in primary ovarian carcinoma patient ascites samples. This work highlights a robust, customizable platform to rapidly develop patient-specific APECs. Significance: This study develops a high-throughput preclinical platform to identify patient-specific antibody–peptide epitope conjugates that target cancer cells and demonstrates the potential of this immunotherapy approach for treating ovarian carcinoma.

Intratumor injection of BCG Ag85A high-affinity peptides enhanced anti-tumor efficacy in PPD-positive melanoma

“…It should be noted that this study was limited to a mouse model of melanoma as our therapeutic strategy holds promise for universal application in cancer treatment. Considering that not all tumors have injectable lesions on their surface, various delivery systems have been investigated, such as copolymer-mediated epitope delivery systems [ 26 , 46 ] and nanoliposomes-mediated delivery systems [ 15 , 20 , 30 ]. Meanwhile, it is difficult to spread the peptides over the whole tumor by intratumoral injection, especially against large tumors.…”

Antibody-epitope conjugates deliver immunogenic T-cell epitopes more efficiently when close to cell surfaces

“… 6 , 12 Therefore, the observed differences in loading efficiency on the different cell lines could be explained by the variability in protease, antibody target, and HLA class I expression levels. 2 , 5 , 6 , 12 …”

“…For AECs, multiple release strategies have proven to be effective, ranging from release within the endo-lysosomal pathway, 1 the extracellular environment, 2 , 3 , 5 , 6 or the cytoplasm. 4 AEC strategies that rely on extracellular delivery use viral epitopes with a free C-terminus.…”

“…Protease expression levels and the amino acids/protease cleavage site in front of the epitope can affect the therapeutic efficiency of these AECs. 5 , 6 Extension of epitopes by one or a few amino acids at the C-terminus abolishes the capacity of AECs to deliver the epitope in MHC class I 11 unless the peptide epitope is imported into the cytoplasm. 4 This suggests that a free C-terminus may be essential for extracellular delivery of epitopes.…”

Enzyme-Instructed Photoactivatable Supramolecular Antigens on Cancer Cell Membranes for Precision-Controlled T-Cell-Based Cancer Immunotherapy

“…However, only a fraction of cancer patients benefit from these immunotherapies . The lack of appropriate endogenous peptide antigens for MHC-I presentation and the resulting poor availability of specific peptide-loaded MHC-I complexes (pMHC-I) to be recognized by their cognate TCRs renders tumors immunologically ‘cold,’ providing underlying causes for these failures. − Accordingly, techniques that can substantially improve the cognate TCR recognizable pMHC-I on tumor surfaces, including increasing MHC-I expression − and enriching tumor-available peptide antigen repertoires − are promising for boosting the CTL-based immunotherapies. Among them, the techniques capable of increasing MHC-I expression and promoting endogenous antigen presentation for tumor cells are popular in boosting ICB therapies. − However, because it is uncertain which kinds of endogenous antigens are presented by tumor cells when only MHC-I expression is increased, they are rarely applied for ACT therapies, neoantigen vaccinations, bispecific antibodies, and other immunotherapeutic modalities that require identified pMHC-I targets .…”