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Abstract：
OBJECTIVE: ATG-101, a bispecific antibody that simultaneously targets the immune checkpoint PD-L1 and the costimulatory receptor 4-1BB, activates exhausted T cells upon PD-L1 crosslinking. Previous studies demonstrated promising anti-tumour efficacy of ATG-101 in preclinical models. Here, we labelled ATG-101 with 89Zr to confirm its tumour targeting effect and tissue biodistribution in a preclinical model. We also evaluated the use of immuno-PET to study tumour uptake of ATG-101 in vivo.
METHODS: ATG-101, anti-PD-L1, and an isotype control were conjugated with p-SCN-Deferoxamine (Df). The Df-conjugated antibodies were radiolabelled with 89Zr, and their radiochemical purity, immunoreactivity, and serum stability were assessed. We conducted PET/MRI and biodistribution studies on [89Zr]Zr-Df-ATG-101 in BALB/c nude mice bearing PD-L1-expressing MDA-MB-231 breast cancer xenografts for up to 10 days after intravenous administration of [89Zr]Zr-labelled antibodies. The specificity of [89Zr]Zr-Df-ATG-101 was evaluated through a competition study with unlabelled ATG-101 and anti-PD-L1 antibodies.
RESULTS: The Df-conjugation and [89Zr]Zr -radiolabelling did not affect the target binding of ATG-101. Biodistribution and imaging studies demonstrated biological similarity of [89Zr]Zr-Df-ATG-101 and [89Zr]Zr-Df-anti-PD-L1. Tumour uptake of [89Zr]Zr-Df-ATG-101 was clearly visualised using small-animal PET imaging up to 7 days post-injection. Competition studies confirmed the specificity of PD-L1 targeting in vivo.
CONCLUSIONS: [89Zr]Zr-Df-ATG-101 in vivo distribution is dependent on PD-L1 expression in the MDA-MB-231 xenograft model. Immuno-PET with [89Zr]Zr-Df-ATG-101 provides real-time information about ATG-101 distribution and tumour uptake in vivo. Our data support the use of [89Zr]Zr-Df-ATG-101 to assess tumour and tissue uptake of ATG-101.
METHODS: ATG-101, anti-PD-L1, and an isotype control were conjugated with p-SCN-Deferoxamine (Df). The Df-conjugated antibodies were radiolabelled with 89Zr, and their radiochemical purity, immunoreactivity, and serum stability were assessed. We conducted PET/MRI and biodistribution studies on [89Zr]Zr-Df-ATG-101 in BALB/c nude mice bearing PD-L1-expressing MDA-MB-231 breast cancer xenografts for up to 10 days after intravenous administration of [89Zr]Zr-labelled antibodies. The specificity of [89Zr]Zr-Df-ATG-101 was evaluated through a competition study with unlabelled ATG-101 and anti-PD-L1 antibodies.
RESULTS: The Df-conjugation and [89Zr]Zr -radiolabelling did not affect the target binding of ATG-101. Biodistribution and imaging studies demonstrated biological similarity of [89Zr]Zr-Df-ATG-101 and [89Zr]Zr-Df-anti-PD-L1. Tumour uptake of [89Zr]Zr-Df-ATG-101 was clearly visualised using small-animal PET imaging up to 7 days post-injection. Competition studies confirmed the specificity of PD-L1 targeting in vivo.
CONCLUSIONS: [89Zr]Zr-Df-ATG-101 in vivo distribution is dependent on PD-L1 expression in the MDA-MB-231 xenograft model. Immuno-PET with [89Zr]Zr-Df-ATG-101 provides real-time information about ATG-101 distribution and tumour uptake in vivo. Our data support the use of [89Zr]Zr-Df-ATG-101 to assess tumour and tissue uptake of ATG-101.
摘要：
目的：ATG-101，一种同时靶向免疫检查点PD-L1和共刺激受体4-1BB的双特异性抗体，PD-L1交联后激活耗尽的T细胞。先前的研究证明了ATG-101在临床前模型中的有希望的抗肿瘤功效。这里,我们用89Zr标记ATG-101，以证实其在临床前模型中的肿瘤靶向作用和组织生物分布。我们还评估了使用免疫PET研究体内ATG-101的肿瘤摄取。
方法:将ATG-101、抗PD-L1和同种型对照与p-SCN-去铁胺(Df)缀合。Df缀合的抗体用89Zr放射性标记,以及它们的放射化学纯度，免疫反应性，和血清稳定性进行了评估。我们对携带PD-L1表达MDA-MB-231乳腺癌异种移植物的BALB/c裸鼠进行了[89Zr]Zr-Df-ATG-101的PET/MRI和生物分布研究。标记的抗体。通过使用未标记的ATG-101和抗PD-L1抗体的竞争研究来评估[89Zr]Zr-Df-ATG-101的特异性。
结果:Df-缀合和[89Zr]Zr-放射性标记不影响ATG-101的靶结合。生物分布和成像研究证明了[89Zr]Zr-Df-ATG-101和[89Zr]Zr-Df-抗PD-L1的生物学相似性。[89Zr]Zr-Df-ATG-101的肿瘤摄取在注射后长达7天使用小动物PET成像清楚地可见。竞争研究证实了体内PD-L1靶向的特异性。
结论：[89Zr]Zr-Df-ATG-101在MDA-MB-231异种移植模型中的体内分布依赖于PD-L1表达。具有[89Zr]Zr-Df-ATG-101的免疫PET提供关于体内ATG-101分布和肿瘤摄取的实时信息。我们的数据支持使用[89Zr]Zr-Df-ATG-101来评估ATG-101的肿瘤和组织摄取。
方法:将ATG-101、抗PD-L1和同种型对照与p-SCN-去铁胺(Df)缀合。Df缀合的抗体用89Zr放射性标记,以及它们的放射化学纯度，免疫反应性，和血清稳定性进行了评估。我们对携带PD-L1表达MDA-MB-231乳腺癌异种移植物的BALB/c裸鼠进行了[89Zr]Zr-Df-ATG-101的PET/MRI和生物分布研究。标记的抗体。通过使用未标记的ATG-101和抗PD-L1抗体的竞争研究来评估[89Zr]Zr-Df-ATG-101的特异性。
结果:Df-缀合和[89Zr]Zr-放射性标记不影响ATG-101的靶结合。生物分布和成像研究证明了[89Zr]Zr-Df-ATG-101和[89Zr]Zr-Df-抗PD-L1的生物学相似性。[89Zr]Zr-Df-ATG-101的肿瘤摄取在注射后长达7天使用小动物PET成像清楚地可见。竞争研究证实了体内PD-L1靶向的特异性。
结论：[89Zr]Zr-Df-ATG-101在MDA-MB-231异种移植模型中的体内分布依赖于PD-L1表达。具有[89Zr]Zr-Df-ATG-101的免疫PET提供关于体内ATG-101分布和肿瘤摄取的实时信息。我们的数据支持使用[89Zr]Zr-Df-ATG-101来评估ATG-101的肿瘤和组织摄取。
