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Significant evidence has indicated that tumor-associated macrophages (TAMs) play a critical role in the proliferation, invasion, angiogenesis, and metastasis of a variety of human carcinomas. In this study, we investigated whether near-infrared fluorescence (NIRF) imaging using a macrophage mannose receptor (MMR; CD206)-targeting agent could be used to noninvasively visualize and quantify changes in TAMs in vivo. The CD206-targeting NIRF agent, Dye-anti-CD206, was prepared and characterized in vitro and in vivo. By using NIRF imaging, we were able to noninvasively image tumor-infiltrating macrophages in the 4T1 mouse breast cancer model. Importantly, longitudinal NIRF imaging revealed the depletion of macrophages in response to zoledronic acid (ZA) treatment. However, ZA alone did not lead to the inhibition of 4T1 tumor growth. We therefore combined anti-macrophage ZA therapy and tumor cytotoxic docetaxel (DTX) therapy in the mouse model. The results demonstrated that this combination strategy could significantly inhibit tumor growth as well as tumor metastasis to the lungs. Based on these findings, we concluded that CD206-targeted molecular imaging can sensitively detect the dynamic changes in tumor-infiltrating macrophages, and that the combination of macrophage depletion and cytotoxic therapy is a promising strategy for the effective treatment of solid tumors.

http://www.thno.org/v05p0597.htm

Peptides are excellent biointerface molecules and diagnostic probes with many advantages such as good penetration, short turnover time, and low cost. We report here an efficient peptide screening strategy based on in situ single bead sequencing on a microarray. Two novel peptides YLFFVFER (H6) and KLRLEWNR (H10) specifically binding to the tumor biomarker human epidermal growth factor receptor 2 (HER2) with aKD of 10(-8) M were obtained from a 10(5) library. Conjugated to nanoparticles, both the H6 and H10 probes showed specific accumulation in HER2-positive tumor tissues in xenografted mice by in vivo imaging.

http://dx.doi.org/10.1021/acs.analchem.5b01588

Well-defined water-soluble block copolymers poly(ethylene glycol)-b-poly(N-(2-hydroxypropyl) methacrylamide-co-N-methacryloylglycylglycine) (PEG-b-P(HPMA-co-MAGG)) and their doxorubicin (Dox) conjugates with different composition and molecular weight were synthesized. These Dox conjugates can form micelles in buffer solution. The physicochemical properties, in vivo biodistribution, blood clearance, and especially the tumor accumulation of copolymers and micelles were studied. Severe liver accumulation can be observed for PEG-b-PMAGG copolymers. This was quite different from their Dox conjugate for which decreased RES uptake and elevated kidney accumulation could be observed. When decrease the negative charge to an appropriate amount such as 8-10 mol %, both RES uptake and kidney accumulation could be suppressed. Obvious tumor accumulation could be achieved especially when the molecular weight were increased from ∼40 to ∼80 KDa. These results provided us with a guideline for the design of nanoscaled drug delivery system as well as a potential option for treating kidney-related cancers.

http://dx.doi.org/10.1021/acs.biomac.5b00460

Cancer-targeted radionuclide therapy is a promising approach for the treatment of a wide variety of malignancies, especially those resistant to conventional therapies. However, to improve the use of targeted radionuclide therapy for the management of cancer patients, the in vivo behaviors, dosimetry, and efficacy of radiotherapeutic agents need to be well characterized and monitored. Molecular imaging, which is a powerful tool for the noninvasive characterization and quantification of biological processes in living subjects at the cellular and molecular levels, plays an important role in the guidance of cancer radionuclide therapy. In this review, we introduce the radiotherapeutics for cancer-targeted therapy and summarize the most recent evidence supporting the use of molecular imaging to guide cancer radionuclide therapy.

http://www.eurekaselect.com/131812/article

Integrin αvβ6 is widely upregulated in variant malignant cancers but is undetectable in normal organs, making it a promising target for cancer diagnostic imaging and therapy. Using streptavidin-biotin chemistry, we synthesized an integrin αvβ6-targeted near-infrared phthalocyanine dye-labeled agent, termed Dye-SA-B-HK, and investigated whether it could be used for cancer imaging, optical imaging-guided surgery, and phototherapy in pancreatic cancer mouse models. Dye-SA-B-HK specifically bound to integrin αvβ6 in vitro and in vivo with high receptor binding affinity. Using small-animal optical imaging, we detected subcutaneous and orthotopic BxPC-3 human pancreatic cancer xenografts in vivo. Upon optical image-guidance, the orthotopically growing pancreatic cancer lesions could be successfully removed by surgery. Using light irradiation, Dye-SA-B-HK manifested remarkable antitumor effects both in vitro and in vivo. (18)F-FDG positron emission tomography (PET) imaging and ex vivo fluorescence staining validated the observed decrease in proliferation of treated tumors by Dye-DA-B-HK phototherapy. Tissue microarray results revealed overexpression of integrin αvβ6 in over 95% cases of human pancreatic cancer, indicating that theranostic application of Dye-DA-B-HK has clear translational potential. Overall, the results of this study demonstrated that integrin αvβ6-specific Dye-SA-B-HK is a promising theranostic agent for the management of pancreatic cancer.

http://linkinghub.elsevier.com/retrieve/pii/S0142-9612(15)00231-8

β-Emitters can produce Cerenkov radiation that is detectable by Cerenkov luminescence imaging (CLI), allowing the combination of PET and CLI with one radiotracer for both tumor diagnosis and visual guidance during surgery. Recently, the clinical feasibility of CLI with the established therapeutic reagent Na(131)I and the PET tracer (18)F-FDG was demonstrated. (68)Ga possesses a higher Cerenkov light output than (18)F and (131)I, which would result in higher sensitivity for CLI and improve the outcome of CLI in clinical applications. However, the research on (68)Ga-based tumor-specific tracers for CLI is limited. In this study, we examined the use of (68)Ga-radiolabeled DOTA-3PRGD2 ((68)Ga-3PRGD2) for dual PET and CLI of orthotopic U87MG human glioblastoma. For this purpose, the Cerenkov efficiencies of (68)Ga and (18)F were measured with the IVIS Spectrum system (PerkinElmer, USA). The CLI signal intensity of (68)Ga was 15 times stronger than that of (18)F. PET and CLI of (68)Ga-3PRGD2 were performed in U87MG human glioblastoma xenografts. Both PET and CLI revealed a remarkable accumulation of (68)Ga-3PRGD2 in the U87MG human glioblastoma xenografts at 1 h p.i. with an extremely low background in the brain when compared with (18)F-FDG. Furthermore, (68)Ga-3PRGD2 was used for dual PET and CLI of orthotopic human glioblastoma. The orthotopic human glioblastoma was clearly visualized by both imaging modalities. In addition, the biodistribution of (68)Ga-3PRGD2 was assessed in normal mice to estimate the radiation dosimetry. The whole-body effective dose is 20.1 ± 3.3 μSv/MBq, which is equal to 3.7 mSv per whole-body PET scan with a 5 mCi injection dose. Thus, (68)Ga-3PRGD2 involves less radiation exposure in patients when compared with (18)F-FDG (7.0 mSv). The use of (68)Ga-3PRGD2 in dual PET and CLI shows great promise for tumor diagnosis and image-guided surgery.

http://dx.doi.org/10.1021/acs.bioconjchem.5b00169

PURPOSE:

This study aimed to explore the diagnostic performance of single photon emission computed tomography / computerized tomography (SPECT/CT) using a new radiotracer 99mTc-RGD-BBN for breast malignant tumor compared with 99mTc-3P4-RGD2.

METHODS:

6 female patients with breast malignant tumors diagnosed by fine needle aspiration cytology biopsy (FNAB) who were scheduled to undergo surgery were included in the study. 99mTc-3P4-RGD2 and 99mTc-RGD-BBN were performed with single photon emission computed tomography (SPECT) at 1 hour after intravenous injection of 299 ± 30 MBq and 293 ± 32 MBq of radiotracers respectively at separate day. The results were evaluated by the Tumor to non-Tumor ratios (T/NT). 99mTc-RGD-BBN and 99mTc-3P4-RGD2 SPECT/CT images were interpreted independently by 3 experienced nuclear medicine physicians using a 3-point scale system. All of the samples were analyzed immunohistochemically to evaluate the integrin αvβ3 and gastrin-releasing peptide receptor (GRPR) expression. The safety, biodistribution and radiation dosimetry of 99mTc-RGD-BBN were also evaluated in the healthy volunteers.

RESULTS:

No serious adverse events were reported in any of the patients during the study. The effective radiation dose entirely conformed to the relevant standards. A total of 6 palpable malignant lesions were detected using 99mTc-RGD-BBN SPECT/CT with clear uptake. All malignant lesions were also detected using 99mTc-3P4-RGD2 SPECT/CT. The results showed that five malignant lesions were with clear uptake and the other one with barely an uptake. 4 malignant cases were found with both αvβ3 and GRPR expression, 1 case with only GRPR positive expression (integrin αvβ3 negative) and 1 case with only integrin αvβ3 positive expression (GRPR negative).

CONCLUSION:

99mTc-RGD-BBN is a safe agent for detecting breast cancer. 99mTc-RGD-BBN may have the potential to make up for the deficiency of 99mTc-3P4-RGD2 in the detection of breast cancer with only GRPR positive expression (integrin αvβ3 negative). The preliminary application of 99mTc-RGD-BBN has demonstrated its powerful potential in breast cancer diagnosis and therapy.

http://www.ncbi.nlm.nih.gov/pmc/articles/pmid/25849333/