Pseudomonas Exotoxin A-Based Immunotherapy Targeting CCK2R-Expressing Colorectal Malignancies: An In Vitro and In Vivo Evaluation

Abstract

Cholecystokinin-2 receptor (CCK2R) has been proven to be a specific biomarker for colorectal malignancies. Immunotoxins are a valuable class of immunotherapy agents consisting of a targeting element and a bacterial or plant toxin. Previous work demonstrated that targeting CCK2R is a good therapeutic strategy for the treatment of colorectal cancer (CRC).In the present study, we developed a new version of CCK2Rtargeting immunotoxin GD9P using a targeted peptide, GD9, as the binding motif and a truncated Pseudomonas exotoxin A (PE38) as the cytokiller. BALB/c nude mice were treated with different doses of GD9P, and pharmacodynamics, pharmacokinetic, and toxicological data were obtained throughout this study. Compared to the parental immunotoxin rCCK8PE38, GD9P exhibited about 1.5-fold yield, higher fluorescence intensity, and increased antitumor activity against human CRC in vitro and in vivo. The IC 50 values of GD9P in vitro ranged from 1.61 to 4.55 nM. Pharmacokinetic studies were conducted in mice with a T 1/2 of 69.315 min. When tumor-bearing nude mice were treated with GD9P at doses ≥2 mg/kg for five doses, a rapid shrinkage in tumor volume and, in some cases, complete remission was observed. A preliminary safety evaluation demonstrated a good safety profile of GD9P as a Pseudomonas exotoxin A-based immunotherapy. The therapy in combination with oxaliplatin can increase the antitumor efficacy and reduce the toxic side effects caused by chemotherapy. In conclusion, the data support the use of GD9P as a promising immunotherapy targeting CCK2R-expressing colorectal malignancies.

Acidity-Triggered “Sticky Spotlight”: CCK2R-Targeted TME-Sensitive NIR Fluorescent Probes for Tumor Imaging In Vivo

“…To understand whether R2SM imaged the tumor tissue via targeting CCK2R, imaging R2S (without CCK2R-targeting MG11) in HT-29 cells (CCK2Rs positive), of which the CCK2R expression was assessed with Western blotting (Figure S19), and R2SM in HepG2 cells (CCK2Rs negative , ) was carried out. From the confocal images (Figure A), weak fluorescence was observed in HT-29 cells incubated with R2S and HepG2 cells incubated with R2SM.…”

The effects of traditional Chinese medicine and dietary compounds on digestive cancer immunotherapy and gut microbiota modulation: A review

“…Therefore, modulating the Clostridium difficile count is beneficial for immune recovery. Interestingly, in some microflora such as Bacteroides fragilis , the cross-reaction between bacterial antigen and tumor neoantigen can activate antitumor T cells ( 66 ). In contrast, the enterotoxins BFT ( Bacteroides fragilis enterotoxin) and IL-17 produced by Bacteroides fragilis induce the differentiation of monocytic myeloid-derived suppressor cells into intestinal epithelial cells, which can selectively upregulate arginase 1 (Arg1) and type 2 NO synthase (NOS2) to produce NO, inhibit T cell proliferation, and promote CRC generation ( 67 ).…”

Hosts and Heterologous Expression Strategies of Recombinant Toxins for Therapeutic Purposes

“…A lot of PE-based chimeras have been described in the literature, conjugating PE and its derivatives with various antibody formats, such as single-chain antibody (scFv), disulfide-stabilized antibody (dsFv), bispecific antibody, micro-antibody, and trivalent antibody, and have yielded promising results in both clinical and preclinical tests. This conjugation has led to the development of mono-or bivalent immunotoxins, demonstrating significant potential in the field [93][94][95][96][97]. PEA is formed via a receptor-binding (blue), translocation (green), and catalytic domain (red).…”