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Journal For Immunotherapy of Cancer Sep 2023B7-H3 is a potential target for pediatric cancers, including neuroblastoma (NB). Vobramitamab duocarmazine (also referred to as MGC018 and herein referred to as vobra...
INTRODUCTION
B7-H3 is a potential target for pediatric cancers, including neuroblastoma (NB). Vobramitamab duocarmazine (also referred to as MGC018 and herein referred to as vobra duo) is an investigational duocarmycin-based antibody-drug conjugate (ADC) directed against the B7-H3 antigen. It is composed of an anti-B7-H3 humanized IgG1/kappa monoclonal antibody chemically conjugated through a cleavable valine-citrulline linker to a ocarmycin-hydroxyenzamide zaindole (vc-seco-DUBA). Vobra duo has shown preliminary clinical activity in B7-H3-expressing tumors.
METHODS
B7-H3 expression was evaluated by flow-cytometry in a panel of human NB cell lines. Cytotoxicity was evaluated in monolayer and in multicellular tumor spheroid (MCTS) models by the water-soluble tetrazolium salt,MTS, proliferation assay and Cell Titer Glo 3D cell viability assay, respectively. Apoptotic cell death was investigated by annexin V staining. Orthotopic, pseudometastatic, and resected mouse NB models were developed to mimic disease conditions related to primary tumor growth, metastases, and circulating tumor cells with minimal residual disease, respectively.
RESULTS
All human NB cell lines expressed cell surface B7-H3 in a unimodal fashion. Vobra duo was cytotoxic in a dose-dependent and time-dependent manner against all cell lines (IC50 range 5.1-53.9 ng/mL) and NB MCTS (IC50 range 17.8-364 ng/mL). Vobra duo was inactive against a murine NB cell line (NX-S2) that did not express human B7-H3; however, NX-S2 cells were killed in the presence of vobra duo when co-cultured with human B7-H3-expressing cells, demonstrating bystander activity. In orthotopic and pseudometastatic mouse models, weekly intravenous treatments with 1 mg/kg vobra duo for 3 weeks delayed tumor growth compared with animals treated with an irrelevant (anti-CD20) duocarmycin-ADC. Vobra duo treatment for 4 weeks further increased survival in both orthotopic and resected NB models. Vobra duo compared favorably to TOpotecan-TEMozolomide (TOTEM), the standard-of-care therapy for NB relapsed disease, with tumor relapse delayed or arrested by two or three repeated 4-week vobra duo treatments, respectively. Further increased survival was observed in mice treated with vobra duo in combination with TOTEM. Vobra duo treatment was not associated with body weight loss, hematological toxicity, or clinical chemistry abnormalities.
CONCLUSION
Vobra duo exerts relevant antitumor activity in preclinical B7-H3-expressing NB models and represents a potential candidate for clinical translation.
Topics: Child; Humans; Mice; Animals; Immunoconjugates; Duocarmycins; Neuroblastoma; Antineoplastic Agents; B7 Antigens; Antibodies, Monoclonal, Humanized
PubMed: 37775116
DOI: 10.1136/jitc-2023-007174 -
Protein Expression and Purification Feb 2024Antibody-mimetic drug conjugate (AMDC) is a cancer cell-targeted drug delivery system based on the non-covalent binding of mutated streptavidin and modified biotin,...
Antibody-mimetic drug conjugate (AMDC) is a cancer cell-targeted drug delivery system based on the non-covalent binding of mutated streptavidin and modified biotin, namely Cupid and Psyche. However, the development of AMDCs is hampered by difficulties in post-translational modification or poor internalization activity. Here, we report an expression, refolding, and purification method for AMDC using a variable heavy chain of heavy chain-only antibodies (VHHs). Monomeric anti-HER2 VHH fused to Cupid was expressed in Escherichia coli inclusion bodies. Solubilization and refolding at optimized reducing conditions and pH levels were selected to form a functional, tetrameric protein (anti-HER2 VHH-Cupid) that can be easily purified based on molecular weight. Anti-HER2 VHH-Cupid non-covalently creates a tight complex with Psyche linked to a potent DNA-alkylating agent, duocarmycin. This complex can be absorbed by the HER2-expressing human breast cancer cell line, KPL-4, and kills KPL-4 cells in vitro and in vivo. The production of a targeting protein with internalizing activity, combined with the non-covalent conjugation of a highly potent payload, renders AMDC a promising platform for developing cancer-targeted therapy.
Topics: Humans; Duocarmycins; Immunoconjugates; Receptor, ErbB-2; Cell Line, Tumor; Drug Delivery Systems
PubMed: 37797818
DOI: 10.1016/j.pep.2023.106375 -
International Journal of Molecular... Apr 2024Acute myeloid leukemia (AML) is a hematological malignancy that is characterized by an expansion of immature myeloid precursors. Despite therapeutic advances, the...
Acute myeloid leukemia (AML) is a hematological malignancy that is characterized by an expansion of immature myeloid precursors. Despite therapeutic advances, the prognosis of AML patients remains poor and there is a need for the evaluation of promising therapeutic candidates to treat the disease. The objective of this study was to evaluate the efficacy of duocarmycin Stable A (DSA) in AML cells in vitro. We hypothesized that DSA would induce DNA damage in the form of DNA double-strand breaks (DSBs) and exert cytotoxic effects on AML cells within the picomolar range. Human AML cell lines Molm-14 and HL-60 were used to perform 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT), DNA DSBs, cell cycle, 5-ethynyl-2-deoxyuridine (EdU), colony formation unit (CFU), Annexin V, RNA sequencing and other assays described in this study. Our results showed that DSA induced DNA DSBs, induced cell cycle arrest at the G2M phase, reduced proliferation and increased apoptosis in AML cells. Additionally, RNA sequencing results showed that DSA regulates genes that are associated with cellular processes such as DNA repair, G2M checkpoint and apoptosis. These results suggest that DSA is efficacious in AML cells and is therefore a promising potential therapeutic candidate that can be further evaluated for the treatment of AML.
Topics: Humans; Apoptosis; Leukemia, Myeloid, Acute; Cell Proliferation; Duocarmycins; Cell Line, Tumor; DNA Breaks, Double-Stranded; HL-60 Cells; Antineoplastic Agents; Cell Cycle Checkpoints; DNA Damage
PubMed: 38673926
DOI: 10.3390/ijms25084342 -
Oncoimmunology 2024Regulatory T cells (Tregs) play a crucial role in mediating immunosuppression in the tumor microenvironment. Furthermore, Tregs contribute to the lack of efficacy and...
Regulatory T cells (Tregs) play a crucial role in mediating immunosuppression in the tumor microenvironment. Furthermore, Tregs contribute to the lack of efficacy and hyperprogressive disease upon Programmed cell death protein 1 (PD-1) blockade immunotherapy. Thus, Tregs are considered a promising therapeutic target, especially when combined with PD-1 blockade. However, systemic depletion of Tregs causes severe autoimmune adverse events, which poses a serious challenge to Treg-directed therapy. Here, we developed a novel treatment to locally and predominantly damage Tregs by near-infrared duocarmycin photorelease (NIR-DPR). In this technology, we prepared anti-CD25 F(ab') conjugates, which site-specifically uncage duocarmycin in CD25-expressing cells upon exposure to NIR light. , CD25-targeted NIR-DPR significantly increased apoptosis of CD25-expressing HT2-A5E cells. When tumors were irradiated with NIR light , intratumoral CD25 Treg populations decreased and Ki-67 and Interleukin-10 expression was suppressed, indicating impaired functioning of intratumoral CD25 Tregs. CD25-targeted NIR-DPR suppressed tumor growth and improved survival in syngeneic murine tumor models. Of note, CD25-targeted NIR-DPR synergistically enhanced the efficacy of PD-1 blockade, especially in tumors with higher CD8/Treg PD-1 ratios. Furthermore, the combination therapy induced significant anti-cancer immunity including maturation of dendritic cells, extensive intratumoral infiltration of cytotoxic CD8 T cells, and increased differentiation into CD8 memory T cells. Altogether, CD25-targeted NIR-DPR locally and predominantly targets Tregs in the tumor microenvironment and synergistically improves the efficacy of PD-1 blockade, suggesting that this combination therapy can be a rational anti-cancer combination immunotherapy.
Topics: Animals; T-Lymphocytes, Regulatory; Mice; Programmed Cell Death 1 Receptor; Tumor Microenvironment; Duocarmycins; Immunoconjugates; Humans; Cell Line, Tumor; Female; Interleukin-2 Receptor alpha Subunit; Immune Checkpoint Inhibitors; Disease Models, Animal; Mice, Inbred C57BL; Apoptosis; Infrared Rays
PubMed: 38915782
DOI: 10.1080/2162402X.2024.2370544