Dataset Information

Highly Potent Immunotoxins Targeting the Membrane-distal N-lobe of GPC3 for Immunotherapy of Hepatocellular Carcinoma.

ABSTRACT: Glypican-3 (GPC3) has become a compelling target for immunotherapy of hepatocellular carcinoma, including antibody-drug conjugate (ADC), and ADC-like immunotoxin. To investigate the impact of epitopes on the potency of ADCs, current study generated a large panel of chicken monoclonal antibodies (mAbs) that targeted 12 different and over-lapping epitopes on GPC3. These mAbs demonstrated a very high affinity with K_d values in the range of 10^-9-10^-14 M, and the highest affinity (K_d value of 0.0214 pM) was 40-fold higher than the previously generated high-affinity mAb YP7 (K_d value of 0.876 nM). Additionally, these mAbs exhibited excellent thermostability with T_m values in the range of 45-82 °C. As a proof-of-concept study for ADC, we made immunotoxins (scFv fused with PE24, the 24-kDa cytotoxic domain of Pseudomonas exotoxin A) based on these mAbs, and we found that immunotoxins targeting the N-lobe of GPC3 were overall much more potent than those targeting the C-lobe and other locations. One representative N-lobe-targeting immunotoxin J80A-PE24 demonstrated 3 to 13-fold more potency than the hitherto best immunotoxin HN3-PE24 that was previously developed. J80A-PE24 could suppress tumor growth much greater than HN3-PE24 in a xenograft mouse model. Combination of J80A-PE24 with an angiogenesis inhibitor FGF401 showed additive effect, which dramatically shrank tumor growth. Our work demonstrated that, due to high affinity, excellent thermostability and potency, chicken mAbs targeting the N-lobe of GPC3 are appealing candidates to develop potent ADCs for immunotherapy of liver cancer.

SUBMITTER: Li J

PROVIDER: S-EPMC8899386 | biostudies-literature | 2022

REPOSITORIES: biostudies-literature

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Highly Potent Immunotoxins Targeting the Membrane-distal N-lobe of GPC3 for Immunotherapy of Hepatocellular Carcinoma.

Li Jingwen J Xiang Lanxin L Wang Qian Q Ma Xuqian X Chen Xin X Zhu Yuankui Y Yang Yaxi Y Huang Le L He Huixia H Xu Lilei L Liang Xinjun X Dong Shuang S Hu Sheng S Li Hanjie H Feng Mingqian M

Journal of Cancer 20220214 4

Glypican-3 (GPC3) has become a compelling target for immunotherapy of hepatocellular carcinoma, including antibody-drug conjugate (ADC), and ADC-like immunotoxin. To investigate the impact of epitopes on the potency of ADCs, current study generated a large panel of chicken monoclonal antibodies (mAbs) that targeted 12 different and over-lapping epitopes on GPC3. These mAbs demonstrated a very high affinity with Kd values in the range of 10-9-10-14 M, and the high ...[more]

PMID: 35281879

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Project description:PurposeHepatocellular carcinoma (HCC) remains one of the most challenging diseases worldwide. Glypican-3 (GPC-3) is a cell surface proteoglycan that is overexpressed on the membrane of HCC cells. The purpose of this study was to develop a target-specific radiofluorinated peptide for positron emission tomography (PET) imaging of GPC3 expression in hepatocellular carcinoma.ProceduresNew GPC3-binding peptides (GP2076 and GP2633) were radiolabeled with F-18 using Al[18F]F labeling approach, and the resulting PET probes were subsequently subject to biological evaluations. A highly hydrophilic linker was incorporated into GP2633 with an aim of reducing the probe uptake in liver and increasing tumor-to-liver (T/L) contrast. Both GP2076 and GP2633 were radiolabeled using Al[18F]F chelation approach. The binding affinity, octanol/water partition coefficient, cellular uptake and efflux, and stability of both F-18 labeled peptides were tested. Tumor targeting efficacy and biodistribution of Al[18F]F-GP2076 and Al[18F]F-GP2633 were determined by PET imaging in HCC-bearing mice. Immunohistochemistry analyses were performed to compare the findings from PET scans.ResultsAl[18F]F-GP2076 and Al[18F]F-GP2633 were rapidly radiosynthesized within 20 min in excellent radiochemical purity (> 97 %). Al[18F]F-GP2633 was determined to be more hydrophilic than Al[18F]F-GP2076 in terms of octanol/water partition coefficient. Both Al[18F]F-GP2076 and Al[18F]F-GP2633 demonstrated good in vitro and in vivo stability and binding specificity to GPC3-positive HepG2 cells. For PET imaging, Al[18F]F-GP2633 exhibited enhanced uptake in HepG2 tumor (%ID/g 3.37 ± 0.35 vs. 2.13 ± 0.55, P = 0.031) and reduced accumulation in liver (%ID/g 1.70 ± 0.26 vs. 3.70 ± 0.98, P = 0.027) at 60 min post-injection (pi) as compared to Al[18F]F-GP2076, resulting in significantly improved tumor-to-liver (T/L) contrast (ratio 2.00 ± 0.18 vs. 0.59 ± 0.14, P = 0.0004). Higher uptake of Al[18F]F-GP2633 in GPC3-positive HepG2 tumor was observed as compared to GPC3-negative McA-RH7777 tumor (%ID/g 3.37 ± 0.35 vs. 1.64 ± 0.03, P = 0.001) at 60 min pi, confirming GPC3-specific accumulation of Al[18F]F-GP2633 in HepG2 tumor.ConclusionThe results demonstrated that Al[18F]F-GP2633 is a promising probe for PET imaging of GPC3 expression in HCC. Convenient preparation, excellent GPC3 specificity in HCC, and favorable excretion profile of Al[18F]F-GP2633 warrant further investigation for clinical translation. PET imaging with a GPC3-specific probe would provide clinicians with vital diagnostic information that could have a significant impact on the management of HCC patients.

Dataset Information

Highly Potent Immunotoxins Targeting the Membrane-distal N-lobe of GPC3 for Immunotherapy of Hepatocellular Carcinoma.

Publications

Highly Potent Immunotoxins Targeting the Membrane-distal N-lobe of GPC3 for Immunotherapy of Hepatocellular Carcinoma.

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