Purpose
The fibroblast activation protein (FAP) is an emerging target for molecular imaging and therapy in cancer. OncoFAP is a novel small organic ligand for FAP with very high affinity. In this ...translational study, we establish
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GaGa-OncoFAP-DOTAGA (
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Ga-OncoFAP) radiolabeling, benchmark its properties in preclinical imaging, and evaluate its application in clinical PET scanning.
Methods
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Ga-OncoFAP was synthesized in a cassette-based fully automated labeling module. Lipophilicity, affinity, and serum stability of
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Ga-OncoFAP were assessed by determining log
D
7.4
, IC
50
values, and radiochemical purity.
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Ga-OncoFAP tumor uptake and imaging properties were assessed in preclinical dynamic PET/MRI in murine subcutaneous tumor models. Finally, biodistribution and uptake in a variety of tumor types were analyzed in 12 patients based on individual clinical indications that received 163 ± 50 MBq
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Ga-OncoFAP combined with PET/CT and PET/MRI.
Results
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Ga-OncoFAP radiosynthesis was accomplished with high radiochemical yields. Affinity for FAP, lipophilicity, and stability of
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Ga-OncoFAP measured are ideally suited for PET imaging. PET and gamma counting–based biodistribution demonstrated beneficial tracer kinetics and high uptake in murine FAP-expressing tumor models with high tumor-to-blood ratios of 8.6 ± 5.1 at 1 h and 38.1 ± 33.1 at 3 h p.i. Clinical
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Ga-OncoFAP-PET/CT and PET/MRI demonstrated favorable biodistribution and kinetics with high and reliable uptake in primary cancers (SUV
max
12.3 ± 2.3), lymph nodes (SUV
max
9.7 ± 8.3), and distant metastases (SUV
max
up to 20.0).
Conclusion
Favorable radiochemical properties, rapid clearance from organs and soft tissues, and intense tumor uptake validate
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Ga-OncoFAP as a powerful alternative to currently available FAP tracers.
There is a pressing need for the development of innovative chemical drug delivery strategies in oncology, since conventional chemotherapeutic agents typically do not localise to solid tumours in ...vivo. It is widely accepted that bivalent antibody formats accumulate in tumours more strongly than monovalent ones and that they should thus be preferred for antibody-based pharmacodelivery approaches. For small molecule-drug conjugates this is less clear. Here, we show that a bivalent ligand against the tumour marker carbonic anhydrase IX leads to an improved tumour-targeting performance compared with the corresponding monovalent counterpart in the SKRC52 model of constitutively CAIX-positive renal cell carcinoma. A bivalent disulfide-linked small drug conjugate with the potent cytotoxic maytansinoid DM1 as the payload can mediate complete eradication of the same tumours, which are resistant to standard-of-care therapeutics, in a proportion of treated mice. In the A375 melanoma model, which preferentially expresses CAIX at sites distant to blood vessels, no measurable tumour accumulation could be observed. Our results suggest that the use of bivalent small molecule ligand-drug conjugates against CAIX may represent an attractive chemical strategy for the treatment of constitutively CAIX-positive kidney cancer.
Soft-tissue sarcomas are a group of malignancies of mesenchymal origin, which typically have a dismal prognosis if they reach the metastatic stage. The observation of rare spontaneous remissions in ...patients suffering from concomitant bacterial infections had triggered the clinical investigation of the use of heat-killed bacteria as therapeutic agents (Coley's toxin), which induced complete responses in patients in the pre-chemotherapy era and is now known to mediate substantial elevations in serum TNF levels.
We designed and developed a novel immunocytokine based on murine TNF sequentially fused to the antibody fragment F8 (specific to extra-domain A of fibronectin). The antitumor activity was studied in two syngeneic murine sarcoma models.
The L19 antibody (specific to extra-domain B of fibronectin) has shown by SPECT imaging procedures to selectively localise on sarcoma in a patient with a peripheral nerve sheath tumour, and immunohistochemical analysis of human soft-tissue sarcoma samples showed comparable antigen expression of EDA and EDB. The antibody-based pharmacodelivery of TNF by the fusion protein 'F8-TNF' to oncofetal fibronectin in sarcoma-bearing mice leads to complete and long-lasting tumour eradications when administered in combination with doxorubicin, the first-line drug for the treatment of sarcomas in humans. Doxorubicin alone did not display any therapeutic effect in both tested models of this study. The cured mice had acquired protective immunity against the tumour, as they rejected subsequent challenges with sarcoma cells.
The findings of this study provide a rationale for the clinical study of the fully human immunocytokine L19-TNF in combination with doxorubicin in patients with soft-tissue sarcoma.
Conventional cytotoxic therapies of cancer often suffer from a lack of specificity, leading to a poor therapeutic index and considerable toxicities to normal organs. An elegant way to overcome the ...disadvantages of conventional tumor therapy is the selective delivery of therapeutics to the tumor site by their conjugation to a carrier molecule specific for a tumor-associated molecular marker. Markers expressed on the tumor's vasculature represent particularly attractive targets for a site-specific pharmacodelivery due to their inherent accessibility for blood-borne agents and the various therapeutic options that they allow, ranging from intraluminal blood coagulation to the recruitment of immune cells.
In this review, we will outline advances in the preclinical and clinical evaluation of antibody-based vascular targeting agents, describe technologies for the discovery of novel vascular targets and discuss future prospects for vascular targeting applications.
ABSTRACT
We explore the effects of tidal interactions on star formation (SF) by analysing a sample of CALIFA survey galaxies. The sample consists of tidally and non-tidally perturbed galaxies whose ...star-forming regions are paired at the closest stellar mass surface densities, even between the same galaxy types. The regions are then compared, both on the resolved star-formation main sequence (SFMS) plane and in annular property profiles. Star-forming regions in tidally perturbed galaxies exhibit flatter SFMS slopes compared to star-forming regions in non-tidally perturbed galaxies. Despite the fact that the annular profiles show star-forming regions in tidally perturbed galaxies as being mostly older, their SF properties are never reduced against those of non-tidally perturbed galaxies. Star-forming regions in non-tidally perturbed galaxies are better candidates for SF suppression (quenching). The lowered SF with increasing stellar mass density in tidally perturbed galaxies may suggest a lower dependence of SF on stellar mass. Though the SFMS slopes, either flatter or steeper, are found independent of stellar mass density, the effect of global stellar mass cannot be ignored when distinguishing between galaxy types. Since a phenomenon or property other than local/global stellar mass may be taking part in the modulation of SF, the integrated SF properties are related to the tidal perturbation parameter. We find weak, but detectable, positive correlations for perturbed galaxies suggesting that tidal perturbations induced by close companions increase the gas accretion rates of these objects.
Abstract
Antibody-based fusion proteins are gaining increasing importance for therapeutic
applications, but the impact of glycosylation on in vivo
biopharmaceutical performance is not always ...completely understood. In this
article, we have analyzed biochemical and pharmaceutical properties of fusion
proteins, consisting of the F8 antibody (specific to the EDA domain of
fibronectin, a marker of tissue remodeling and of angiogenesis) and of the p40
subunit of interleukin-12, an inhibitor of inflammation. The corresponding
fusion protein (F8-IL12p40), which inhibits colitis development in mice, is a
glycosylated protein with suboptimal disease targeting properties in
vivo. Since the protein was extensively glycosylated, as evidenced
by PNGase F treatment and mass spectrometric analysis, we mutated four
asparagine residues in various combinations. The corresponding proteins
exhibited similar biochemical and antigen-binding properties, but differences in
thermal stability and bioactivity. Asparagine mutations did not lead to recovery
of disease targeting performance in vivo, as evidenced by
quantitative biodistribution studies with radioiodinated protein preparations in
tumor-bearing mice. By contrast, an almost complete recovery of targeting was
achieved with an enzymatically deglycosylated protein preparation. These
findings reinforce the concept that different glycostructures can have an impact
on tissue distribution properties.
Cytokines have long been used for therapeutic applications in cancer patients. Substantial side effects and unfavorable pharmacokinetics limit their application and may prevent dose escalation to ...therapeutically active regimens. Antibody-cytokine fusion proteins (often referred to as immunocytokines) may help localize immunomodulatory cytokine payloads to the tumor, thereby activating anticancer immune responses. A variety of formats (e.g., intact IgGs or antibody fragments), molecular targets (e.g., extracellular matrix components and cell membrane antigens) and cytokine payloads have been considered for the development of this novel class of biopharmaceuticals. This review presents the basic concepts on the design and engineering of immunocytokines, reviews their potential limitations, points out emerging opportunities and summarizes key features of preclinical and clinical-stage products.
Graphical abstract Display omitted
The extra domain A (ED A) of fibronectin has been identified as a tumor vessel specific neovascular marker in glioma. Antibody based vascular targeting against ED A of fibronectin allows precise ...accumulation of photosensitizer in glioma microvasculature and thereby promises to overcome drawbacks of current photodynamic therapy (PDT) for glioma treatment. Our aim was to characterize microcirculatory consequences of F8-small immunoprotein (SIP) mediated PDT by intravital microscopy (IVM) and to analyze the effects on glioma growth. For IVM SF126 glioma cells were implanted into dorsal skinfold-chamber of nude mice. PDT was performed after intravenous injection of photosensitizer (PS)-coupled F8-SIP or PBS (n = 4). IVM was performed before and after PDT for 4 days. Analysis included total and functional (TVD, FVD) vessel densities, perfusion index (PI), microvascular permeability and blood flow rate (Q). To assess tumor growth SF126 glioma cells were implanted subcutaneously. PDT was performed as a single and repetitive treatment after PS-F8-SIP injection (n = 5). Subcutaneous tumors were treated after uncoupled F8-SIP injection as control group (n = 5). PDT induced microvascular stasis and thrombosis with reduced FVD (24 h: 115.98 ± 0.7 vs. 200.8 ± 61.9 cm/cm
2
) and PI (39 ± 11 vs. 70 ± 10 %), whereas TVD was not altered (298 ± 39.2 vs. 278.2 ± 51 cm/cm
2
). Microvascular dysfunction recovered 4 days after treatment. Microvascular dysfunction led to a temporary reduction of glioma growth in the first 48 h after treatment with complete recovery 5 days after treatment. Repetitive PDT resulted in sustained reduction of tumor growth. F8-SIP mediated PDT leads to microvascular dysfunction and reduced glioma growth in a preclinical glioma model with recovery of microcirculation 4 days after treatment. Repetitive application of PDT overcomes microvascular recovery and leads to prolonged antiglioma effects.
Magnetic levan was synthesized by co-precipitating D-fructofuranosyl homopolysaccharide with a solution containing Fe2+ and Fe3+ in alkaline conditions at 100°C. The magnetic levan particles were ...characterized by scanning electron microscopy (SEM), magnetization measurements, X-ray diffractometry (XRD) and infrared spectroscopy (IR). Afterwards, magnetic levan particles were functionalized by NaIO4 oxidation and used as matrices for trypsin covalent immobilization. Magnetite and magnetic levan particles were both heterogeneous in shape and levan–magnetite presented bigger sizes compared to magnetite according to SEM images. Magnetic levan particles exhibited a magnetization 10 times lower as compared to magnetite ones, probably, due to the coating layer. XRD diffractogram showed that magnetite is the dominant phase in the magnetic levan. Infrared spectroscopy showed characteristics absorption bands of levan and magnetite (O–H, C–O–C and Fe–O bonds). The immobilized trypsin derivative was reused 10 times and lost 16% of its initial specific activity only. Therefore, these magnetic levan particles can be proposed as an alternative matrices for enzyme immobilization.
► The magnetic levan particles presented larger size variation than magnetite particles due to the changes produced by coating. ► The utilization of magnetic levan particles showed to be efficacious for immobilization of enzymes as trypsin. ► Magnetic particles can be planned as other matrix for immobilization of biomolecule in various division processes in biotechnology.
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