Dataset Information

Preclinical Evaluation of ^99mTc-ZHER2:41071, a Second-Generation Affibody-Based HER2-Visualizing Imaging Probe with a Low Renal Uptake.

ABSTRACT: Radionuclide imaging of HER2 expression in tumours may enable stratification of patients with breast, ovarian, and gastroesophageal cancers for HER2-targeting therapies. A first-generation HER2-binding affibody molecule [^99mTc]Tc-ZHER2:V2 demonstrated favorable imaging properties in preclinical studies. Thereafter, the affibody scaffold has been extensively modified, which increased its melting point, improved storage stability, and increased hydrophilicity of the surface. In this study, a second-generation affibody molecule (designated ZHER2:41071) with a new improved scaffold has been prepared and characterized. HER2-binding, biodistribution, and tumour-targeting properties of [^99mTc]Tc-labelled ZHER2:41071 were investigated. These properties were compared with properties of the first-generation affibody molecules, [^99mTc]Tc-ZHER2:V2 and [^99mTc]Tc-ZHER2:2395. [^99mTc]Tc-ZHER2:41071 bound specifically to HER2 expressing cells with an affinity of 58 ± 2 pM. The renal uptake for [^99mTc]Tc-ZHER2:41071 and [^99mTc]Tc-ZHER2:V2 was 25-30 fold lower when compared with [^99mTc]Tc-ZHER2:2395. The uptake in tumour and kidney for [^99mTc]Tc-ZHER2:41071 and [^99mTc]Tc-ZHER2:V2 in SKOV-3 xenografts was similar. In conclusion, an extensive re-engineering of the scaffold did not compromise imaging properties of the affibody molecule labelled with ^99mTc using a GGGC chelator. The new probe, [^99mTc]Tc-ZHER2:41071 provided the best tumour-to-blood ratio compared to HER2-imaging probes for single photon emission computed tomography (SPECT) described in the literature so far. [^99mTc]Tc-ZHER2:41071 is a promising candidate for further clinical translation studies.

SUBMITTER: Oroujeni M

PROVIDER: S-EPMC7967187 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Affibody molecules are small affinity-engineered scaffold proteins which can be engineered to bind to desired targets. The therapeutic potential of using an affibody molecule targeting HER2, fused to an albumin-binding domain (ABD) and conjugated with the cytotoxic maytansine derivate MC-DM1 (AffiDC), has been validated. Biodistribution studies in mice revealed an elevated hepatic uptake of the AffiDC, but histopathological examination of livers showed no major signs of toxicity. However, previous clinical experience with antibody drug conjugates have revealed a moderate- to high-grade hepatotoxicity in treated patients, which merits efforts to also minimize hepatic uptake of the AffiDCs. In this study, the aim was to reduce the hepatic uptake of AffiDCs and optimize their in vivo targeting properties. We have investigated if incorporation of hydrophilic glutamate-based spacers adjacent to MC-DM1 in the AffiDC, (ZHER2:2891)2-ABD-MC-DM1, would counteract the hydrophobic nature of MC-DM1 and, hence, reduce hepatic uptake. Two new AffiDCs including either a triglutamate-spacer-, (ZHER2:2891)2-ABD-E3-MC-DM1, or a hexaglutamate-spacer-, (ZHER2:2891)2-ABD-E6-MC-DM1 next to the site of MC-DM1 conjugation were designed. We radiolabeled the hydrophilized AffiDCs and compared them, both in vitro and in vivo, with the previously investigated (ZHER2:2891)2-ABD-MC-DM1 drug conjugate containing no glutamate spacer. All three AffiDCs demonstrated specific binding to HER2 and comparable in vitro cytotoxicity. A comparative biodistribution study of the three radiolabeled AffiDCs showed that the addition of glutamates reduced drug accumulation in the liver while preserving the tumor uptake. These results confirmed the relation between DM1 hydrophobicity and liver accumulation. We believe that the drug development approach described here may also be useful for other affinity protein-based drug conjugates to further improve their in vivo properties and facilitate their clinical translatability.

Project description:INTRODUCTION:The ?v?3 integrin, which is expressed by angiogenic epithelium and some tumor cells, is an attractive target for the development of both imaging agents and therapeutics. While optimal implementation of ?v?3-targeted therapeutics will require a priori identification of the presence of the target, the clinical evaluation of these compounds has typically not included parallel studies with ?v?3-targeted diagnostics. This is at least partly due to the relatively limited availability of PET radiopharmaceuticals in comparison to those labeled with (99m)Tc. In an effort to begin to address this limitation, we evaluated the tumor uptake of (99m)Tc-NC100692, a cyclic RGD peptide that binds to ?v?3 with ~1-nM affinity, in an ?v?3-positive tumor model as well as its in vivo specificity. METHODS:MicroSPECT imaging was used to assess the ability of cilengitide, a therapeutic with high affinity for ?v?3, to block and displace (99m)Tc-NC100692 in an orthotopic U87 glioma tumor. The specificity of (99m)Tc-NC100692 was quantitatively evaluated in mice bearing subcutaneous U87MG tumors, by comparison of the biodistribution of (99m)Tc-NC100692 with that of the non-specific structural analogue (99m)Tc-AH-111744 and by blocking uptake of (99m)Tc-NC100692 with excess unlabeled NC100692. RESULTS:MicroSPECT imaging studies demonstrated that uptake of (99m)Tc-NC100692 in the intracranial tumor model was both blocked and displaced by the ?v?3-targeted therapeutic cilengitide. Biodistribution studies provided quantitative confirmation of these imaging results. Tumor uptake of (99m)Tc-NC100692 at 1h post-injection was 2.8 ± 0.7% ID/g compared to 0.38 ± 0.1% ID/g for (99m)Tc-AH-111744 (p < 0.001). Blocking (99m)Tc-NC100692 uptake by pre-injecting the mice with excess unlabeled NC100692 reduced tumor uptake by approximately five-fold, to 0.68 ± 0.3% ID/g (p = 0.01). CONCLUSION:These results confirm that (99m)Tc-NC100692 does, in fact, target the ?v?3 integrin and may, therefore, be useful in identifying patients prior to anti-?v?3 therapy as well as monitoring the response of these patients to therapy.

Dataset Information

Preclinical Evaluation of ^99mTc-ZHER2:41071, a Second-Generation Affibody-Based HER2-Visualizing Imaging Probe with a Low Renal Uptake.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Dataset Information

Preclinical Evaluation of 99mTc-ZHER2:41071, a Second-Generation Affibody-Based HER2-Visualizing Imaging Probe with a Low Renal Uptake.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Preclinical Evaluation of ^99mTc-ZHER2:41071, a Second-Generation Affibody-Based HER2-Visualizing Imaging Probe with a Low Renal Uptake.