Molecular imaging of HER2 expression in breast cancer patients using a novel peptide-based tracer 99mTc-HP-Ark2: a pilot study.

BACKGROUND: Due to the temporal and spatial heterogeneity of human epidermal growth factor receptor 2 (HER2) expression in breast tumors, immunohistochemistry (IHC) cannot accurately reflect the HER2 status in real time, which may cause misguided treatment decisions. HER2-specific imaging can noninvasively determine HER2 status in primary and metastatic tumors. In this study, HER2 expression in breast cancer patients was determined in vivo by SPECT/CT of 99mTc-HP-Ark2, comparing with PET/CT of 18F-FDG lesion by lesion. METHODS: A novel HER2-targeted peptide probe 99mTc-HP-Ark2 was constructed. Biodistribution and nanoScan SPECT/CT imaging were performed in mice models. The correlation between the quantified tumor uptake and HER2 expression in tumor cells was analyzed. In the pilot clinical study, a total of 34 breast cancer patients (mean age ± SD: 49 ± 10 y) suspected of having breast cancer according to mammography or ultrasonography were recruited at Peking Union Medical College Hospital, and 99mTc-HP-Ark2 SPECT/CT and 18F-FDG PET/CT were carried out with IHC and fluorescence in situ hybridization as validation. RESULTS: Small animal SPECT/CT of 99mTc-HP-Ark2 clearly identified tumors with different HER2 expression. The quantified tumor uptake and tumor HER2 expression showed a significant linear correlation (r = 0.932, P < 0.01). Among the 36 primary lesions in the 34 patients, when IHC (2 +) or IHC (3 +) was used as the positive evaluation criterion, 99mTc-HP-Ark2 SPECT/CT imaging with a tumor-to-background ratio of 1.44 as the cutoff value reflected the HER2 status with sensitivity of 89.5% (17/19), specificity of 88.2% (15/17) and accuracy of 88.9% (32/36), while the 18F-FDG PET/CT showed sensitivity of 78.9% (15/19), specificity of 70.6% (12/17) and accuracy of 75.0% (27/36). In particular, 100% of IHC (3 +) tumors were all identified by 99mTc-HP-Ark2 SPECT/CT imaging. CONCLUSION: 99mTc-HP-Ark2 SPECT/CT can provide a specific, noninvasive evaluation of HER2 expression in breast cancer, showing great potential to guide HER2-targeted therapies in clinical practice. CLINICALTRIALS: gov Trial registration: NCT04267900. Registered 11th February 2020. Retrospectively registered, https://www. CLINICALTRIALS: gov/ct2/results?pg=1&load=cart&id=NCT04267900 .

Developing PEGylated Reversed D-Peptide as a Novel HER2-Targeted SPECT Imaging Probe for Breast Cancer Detection.

Human epidermal growth factor receptor-2 (HER2)-enriched breast cancer is characterized by strong invasiveness, high recurrence rate, and poor prognosis. HER2-specific imaging can help screening right patients for appropriate HER2-targeted therapies. Previously, we have developed a 99mTc-labeled HER2-targeted H6 peptide for SPECT imaging of breast cancer. However, the poor metabolic stability and high gallbladder uptake hamper its clinical application. In this study, a retro-inverso D-peptide of H6 (RDH6) was designed to increase the metabolic stability. PEGylation was used to improve its water solubility and in vivo pharmacokinetics. The results showed that the D-amino acids in 99mTc-PEG4-RDH6 brought better metabolic stability than 99mTc-PEG4-H6, thus achieving higher tumor uptake. As the length of the PEG chain increases, the hydrophilicity of the probes gradually increased, which may also be the main cause for the decreased liver uptake. Compared with radiotracers modified by PEG4 and PEG12, 99mTc-PEG24-RDH6 had a comparable tumor uptake and the lowest liver radioactivity. The SPECT imaging demonstrated that 99mTc-PEG24-RDH6 could specifically distinguish HER2-positive tumors from HER2-negative tumors with better imaging contrast, which thus has the potential for clinical screening of HER2-positive breast patients.

Improved in Vivo Targeting Capability and Pharmacokinetics of 99mTc-Labeled isoDGR by Dimerization and Albumin-Binding for Glioma Imaging.

Previously, we successfully developed the c(phg-isoDGRk) peptide as a novel integrin α5ß1-targeted SPECT imaging probe 99mTc-HisoDGR for Glioma imaging. However, the fast clearance of 99mTc-HisoDGR in blood reduced its tumor accumulation and retention, which would be the obstacles for further clinical application. Dimerization and albumin-binding strategies have been proven as effective approaches to improve tumor targeting capability and blood circulation time of radiotracers. In this study, the novel PEGylated dimeric isoDGR peptides (termed 3PisoDGR2) and its analogue with an albumin binder (termed AB-3PisoDGR2) were designed, and the corresponding radiotracers 99mTc-3PisoDGR2 and 99mTc-AB-3PisoDGR2 were fabricated and assessed for tumor-targeting and in vivo pharmacokinetics properties in subcutaneous and orthotopic tumor models. The dimerization of isoDGR peptide provided higher binding affinity to tumor cells and longer blood circulation time than the original monomeric isoDGR peptide, resulting in twice increased tumor uptake (99mTc-3PisoDGR2 2.51 ± 0.17 %ID/g vs 99mTc-PisoDGR 1.17 ± 0.21 %ID/g, P < 0.01) at 0.5 h post-injection (p.i.) and enhanced tumor to nontargeting tissue ratios (T/NT) in most normal organs. The blocking study indicated that the tumor uptake was receptor-mediated specifically. NanoScanSPECT/CT imaging of 99mTc-3PisoDGR2 in glioma tumor-bearing model showed clear visions of tumors with low background, except high uptake in excretion system including kidneys and bladder at all detected time points (0.5, 1, and 2 h p.i.). The orthotopic glioma tumor could also be clearly visualized by nanoScanSPECT/CT imaging with 99mTc-3PisoDGR2. The addition of albumin-binding entity further prolonged blood circulation time and reached higher tumor uptake for 99mTc-AB-3PisoDGR2. However, since 99mTc-AB-3PisoDGR2 is less capable of passing BBB than 99mTc-3PisoDGR2, 99mTc-3PisoDGR2 is preferable for the in situ glioma imaging. In conclusion, 99mTc-3PisoDGR2 represents an improved molecular probe for integrin α5ß1-targeted tumor imaging, showing more potential for further clinical application.

A Dual pH-Responsive DOX-Encapsulated Liposome Combined with Glucose Administration Enhanced Therapeutic Efficacy of Chemotherapy for Cancer.

BACKGROUND: The acidic microenvironment of cancer can promote tumor metastasis and drug resistance. Acidic tumor microenvironment-targeted therapy is currently an important means for treating tumors, inhibiting metastasis, and overcoming drug resistance. In this study, a dual pH-responsive DOX-encapsulated liposome (DOPE-DVar7-lip@DOX) was designed and fabricated for targeting the acidic tumor microenvironment. On the one hand, the response of acid-sensitive peptide (DVar7) to the acidic tumor microenvironment increased the uptake of liposomes in tumors and prolonged the retention time; on the other hand, the response of acid-sensitive phospholipid (DOPE) to the acidic tumor microenvironment improved the controlled release of DOX in tumors. METHODS: The acid-sensitive peptide DVar7 modified liposomes can be obtained by simple incubation of DSPE-DVar7 with DOX-loaded DOPE liposomes (DOPE-lip@DOX). The tumor targeting of the dual pH-responsive liposome was investigated in vitro and in vivo by near-infrared fluorescence imaging. The tumor therapeutic efficacy of DOPE-DVar7-lip@DOX was evaluated in breast cancer mouse model using the traditional liposome as a control. Moreover, we regulated the tumor microenvironment acidity by injecting glucose to further enhance the therapeutic efficacy of cancer. RESULTS: DVar7 can allosterically insert into the tumor cell membrane in the acidic tumor microenvironment to enhance the tumor uptake of liposomes and prolong the retention time of liposomes in tumor. In addition, the therapeutic efficacy of pH-responsive liposomes can be further enhanced by glucose injection regulating the acidity of tumor microenvironment. DISCUSSION: DVar7 modified acid-sensitive nanocarriers combined with acidity regulation have great potential to improve drug resistance in clinical practice, thus improving the response rate and therapeutic effect of chemotherapy.

Host-Guest Polypyrrole Nanocomplex for Three-Stimuli-Responsive Drug Delivery and Imaging-Guided Chemo-Photothermal Synergetic Therapy of Refractory Thyroid Cancer.

Despite the good prognosis of the low-risk thyroid cancer, there are no truly effective treatments for radioactive iodine-refractory thyroid cancer. Herein, a novel theranostic nanoplatform, as well as a smart doxorubucin (DOX) delivery system is fabricated. Gelatin-stabilized polypyrrole nanoparticles are reported for the first time. The combination of gelatin-stabilized polypyrrole and cyclodextrin-DOX complexes enabling three-stimuli-controlled drug delivery, including the enzyme-sensitive, pH-sensitive and photothermal-sensitive drug release, exhibiting a new way to equip photothermal agents with precisely controlled drug delivery. Anti-galectin-3 antibodies are utilized as the targeting molecules of nanoparticles in the first time, which surprisingly increase intracellular DOX uptake by enhanced clathrin-mediated endocytosis, showing galectin-3 can be employed as a highly efficient target of drug delivery systems. The nanoparticles achieve excellent photoacoustic imaging effect, enabled chemo-photothermal combined therapy with pinpointed drug delivery. Compared to free DOX, these multifunctional nanoparticles decrease the heart damage, but greatly increase the tumor/heart ratio of DOX concentration by 12.9-fold. The tumors are completely eradicated without any recurrence after the in vivo combined therapy. To the best of the authors' knowledge, this is also the first report to apply photoacoustic imaging-guided chemo-photothermal therapy for thyroid cancer, showing great potential to solve the dilemma in thyroid cancer therapy.