Nontransformed and Cancer Cells Can Utilize Different Endocytic Pathways To Internalize Dendritic Nanoparticle Variants: Implications on Nanocarrier Design.

Three hyperbranched polyglycerol nanoparticle (HPG NP) variants were synthesized and fluorescently labeled for the study of their cellular interactions. The polymeric nanoparticle that contains a hydrophobic core and a hydrophilic HPG shell, HPG-C10-HPG, is taken up faster by HT-29 cancer cells than nontransformed cells, while similar uptake rates are observed with both cell types for the nanoparticle HPG-C10-PEG that contains a hydrophobic core and a polyethylene glycol shell. The nanoparticle HPG-104, containing neither the hydrophobic core nor the polyethylene glycol shell, is taken up faster by nontransformed cells than HT-29 cells. Importantly, cancer and normal cells can utilize different endocytic mechanisms for the internalization of these HPG NPs. Both HPG-C10-HPG and HPG-C10-PEG are taken up by HT-29 cells through clathrin-mediated endocytosis and macropinocytosis. Nontransformed cells, however, take up HPG-C10-HPG and HPG-104 through macropinocytosis, while these cells utilize both clathrin-mediated endocytosis and macropinocytosis to internalize HPG-C10-PEG.

Investigation of hydrophobically derivatized hyperbranched polyglycerol with PEGylated shell as a nanocarrier for systemic delivery of chemotherapeutics.

We report the synthesis and characterization of a polymeric nanoparticle (NP) based on hyperbranched polyglycerol (HPG) containing a hydrophobic core and a hydrophilic shell, and assessed its suitability to be developed as a systemic anticancer drug carrier. HPG NP displayed low toxicity to primary cell cultures and were well-tolerated in mice after intravenous administration. When tested in mice tumor xenograft models, HPG NP accumulated significantly in the tumors with low accumulation in the liver and the spleen. In vitro studies demonstrated that HPG NP was capable of hydrophobically binding docetaxel and releasing it in a controlled manner. The HPG NP formulation of docetaxel conferred a preferential protective effect on primary non-cancerous cells while effectively killing cancer cells, indicating great potential for widening its therapeutic index. Taken together, these data indicate that HPG NP is a highly promising nanocarrier platform for systemic delivery of anticancer drugs. FROM THE CLINICAL EDITOR: The use of polyethylene glycol on nano-carriers as "stealth" to deliver intravenous drugs is well known. Here, the authors developed polymeric nanoparticle (NP) with hyperbranched polyglycerol (HPG) and tested its efficacy in delivering docetaxel. The results showed that this formulation could preferentially killed cancer cells with a high therapeutic index. It seems that this platform could have a great potential in cancer therapy.

Physiologically based pharmacokinetic model for composite nanodevices: effect of charge and size on in vivo disposition.

PURPOSE: To characterize temporal exposure and elimination of 5 gold/dendrimer composite nanodevices (CNDs) (5 nm positive, negative, and neutral, 11 nm negative, 22 nm positive) in mice using a physiologically based mathematical model. METHODS: 400 ug of CNDs is injected intravenously to mice bearing melanoma cell lines. Gold content is determined from plasma and tissue samples using neutron activation analysis. A physiologically based pharmacokinetic (PBPK) model is developed for 5 nm positive, negative, and neutral and 11 nm negative nanoparticles and extrapolated to 22 nm positive particles. A global sensitivity analysis is performed for estimated model parameters. RESULTS: Negative and neutral particles exhibited similar distribution profiles. Unique model parameter estimates and distribution profiles explain similarities and differences relative to positive particles. The model also explains mechanisms of elimination by kidney and reticuloendothelial uptake in liver and spleen, which varies with particle size and charge. CONCLUSION: Since the PBPK model can capture the diverse temporal profiles of non-targeted nanoparticles, we propose that when specific binding ligands are lacking, size and charge of nanodevices govern most of their in vivo interactions.

Fabrication of {198Au0} radioactive composite nanodevices and their use for nanobrachytherapy.

We describe the simple fabrication of poly({198Au}) radioactive gold-dendrimer composite nanodevices in distinct sizes (diameter between 10 nm and 29 nm) for targeted radiopharmaceutical dose delivery to tumors in vivo. Irradiation of aqueous solutions of 197Au containing poly(amidoamine) dendrimer tetrachloroaurate salts or {197Au0} gold-dendrimer nanocomposites in a nuclear reactor resulted in the formation of positively charged and soluble poly{198Au0} radioactive composite nanodevices (CNDs). A mouse melanoma tumor model was used to test whether the poly{198Au0} CNDs can deliver a therapeutic dose. A single intratumoral injection of poly{198Au0}(d=22nm) CNDs in phosphate-buffered saline delivering a dose of 74 muCi resulted after 8 days in a statistically significant 45% reduction in tumor volume, when compared with untreated groups and those injected with the "cold" nanodevice. No clinical toxicity was observed during the experiments. This study provides the first proof of principle that radioactive CNDs can deliver therapeutic doses to tumors.

Palliation or Prolongation? The Impact of a Peer-Review Intervention on Shortening Radiotherapy Schedules for Bone Metastases.

PURPOSE: Shorter fractionation radiation regimens for palliation of bone metastases result in lower financial and social costs for patients and their caregivers and have similar efficacy as longer fractionation schedules, although practice patterns in the United States show poor adoption. We investigated whether prospective peer review can increase use of shorter fractionation schedules. METHODS: In June 2016, our practice mandated peer review of total dose and fractionation for all patients receiving palliative treatment during our weekly chart rounds. We used descriptive statistics and Fisher's exact test to compare lengths of treatment of uncomplicated bone metastases before and after implementation of the peer review process. RESULTS: Between July 2015 and December 2016, a total of 242 palliative treatment courses were delivered, including 105 courses before the peer review intervention and 137 after the intervention. We observed greater adoption of shorter fractionation regimens after the intervention. The use of 8 Gy in one fraction increased from 2.8% to 13.9% of cases postadoption. Likewise, the use of 20 Gy in five fractions increased from 25.7% to 32.8%. The use of 30 Gy in 10 fractions decreased from 55.2% to 47.4% ( P = .002), and the use of ≥ 11 fractions decreased from 16.2% before the intervention to 5.8% after ( P = .006). CONCLUSION: Prospective peer review of palliative regimens for bone metastases can lead to greater adoption of shorter palliative fractionation schedules in daily practice, in accordance with national guidelines. This simple intervention may therefore benefit patients and their caregivers as well as provide value to the health care system.

Significant effect of size on the in vivo biodistribution of gold composite nanodevices in mouse tumor models.

There is growing interest in developing tissue-specific multifunctional drug delivery systems with the ability to diagnose or treat several diseases. One class of such agents, composite nanodevices (CNDs), is multifunctional nanomaterials with several potential medical uses, including cancer imaging and therapy. Nanosized metal-dendrimer CNDs consist of poly(amidoamine) dendrimers (in various sizes, surface substituents, and net charges) and inorganic nanoparticles, properties of both of which can be individually modified and optimized. In this study we examine effects of size and surface charge on the behavior of Au-dendrimer CNDs in mouse tumor models. Quantitative biodistribution and excretion analyses including 5-nm and 22-nm positive surface, 5-nm and 11-nm negative surface, and a 5-nm neutral surface CNDs were carried out in the B16 mouse melanoma tumor model system. Results seen with the 22-nm CND in the B16 melanoma model were corroborated in a prostate cancer mouse tumor model system. Quantitative in vivo studies confirm the importance of charge and show for the first time the importance of size in affecting CND biodistribution and excretion. Interestingly, CNDs of different size and/or surface charge had high levels of uptake ("selective targeting") to certain organs without specific targeting moieties placed on their surfaces. We conclude that size and charge greatly affect biodistribution of CNDs. These findings have significance for the design of all particle-based nanodevices for medical uses. The observed organ selectivity may make these nanodevices exciting for several targeted medical applications.

Nanoparticle targeting of anticancer drug improves therapeutic response in animal model of human epithelial cancer.

Prior studies suggested that nanoparticle drug delivery might improve the therapeutic response to anticancer drugs and allow the simultaneous monitoring of drug uptake by tumors. We employed modified PAMAM dendritic polymers <5 nm in diameter as carriers. Acetylated dendrimers were conjugated to folic acid as a targeting agent and then coupled to either methotrexate or tritium and either fluorescein or 6-carboxytetramethylrhodamine. These conjugates were injected i.v. into immunodeficient mice bearing human KB tumors that overexpress the folic acid receptor. In contrast to nontargeted polymer, folate-conjugated nanoparticles concentrated in the tumor and liver tissue over 4 days after administration. The tumor tissue localization of the folate-targeted polymer could be attenuated by prior i.v. injection of free folic acid. Confocal microscopy confirmed the internalization of the drug conjugates into the tumor cells. Targeting methotrexate increased its antitumor activity and markedly decreased its toxicity, allowing therapeutic responses not possible with a free drug.

Tetrathiomolybdate blocks bFGF- but not VEGF-induced incipient angiogenesis in vitro.

BACKGROUND: Angiogenesis is a multi-step process which involves endothelial cell sprouting from existing blood vessels, followed by migration, proliferation, alignment and tube formation. Tetrathiomolybdate (TM) is a multi-hit antiangiogenic agent with actions against multiple angiogenic pathways. These inhibitory effects of TM are attributed to its potent copper level-reducing property. Copper is needed for activation of various angiogenic pathways at the transcriptional and protein levels. MATERIALS AND METHODS: The direct effects of TM on angiogenesis of endothelial cells were examined using an in vitro sprout-forming system. RESULTS: It was shown that depletion of copper by TM selectively repressed bFGF-induced, but not VEGF-induced sprout formation (an early angiogenic step). CONCLUSION: This model permitted the separation of VEGF- and bFGF- induced early angiogenesis in vitro, and indicated the existence of mechanistic differences between bFGF- and VEGF- induced early angiogenic events.

Combination tetrathiomolybdate and radiation therapy in a mouse model of head and neck squamous cell carcinoma.

OBJECTIVE: To assess the effect of combining tetrathiomolybdate therapy and radiation treatment (RT) on tumor growth in the mouse head and neck squamous cell carcinoma (HNSCC) model. DESIGN: One million HNSCC cells were injected subcutaneously into the flanks of C3H/HeJ mice and the tumors grown to an average of 301 mm3 (day 0). Mice were randomized into 4 groups: (a) no therapy, (b) tetrathiomolybdate alone, (c) RT alone, or (d) tetrathiomolybdate + RT. Data from 3 experiments with these 4 groups were analyzed. A gaussian mixed model was fit to the initialized logarithm of the tumor size counts between days 7 and 16 (linear component), and growth rates were compared. Assays using 3-(4,5-dimethylthiazol-2yl)-2,5 diphenyltetrazolium bromide (MTT) were conducted on HNSCC cells in culture with varying doses of tetrathiomolybdate. INTERVENTIONS: Treated mice were given tetrathiomolybdate in their water and observed for clinical evidence of toxic effects associated with copper depletion as measured by ceruloplasmin assay. When tumor sizes reached an average of 535 mm(3), mice receiving RT were given a single fraction of 750 rad (7.5 Gy), a dose determined in previous experiments to slow but not cure tumor growth, permitting an examination of interaction of radiation with tetrathiomolybdate. RESULTS: Data from 3 separate experiments were analyzed. There were a total of 37 mice in the untreated group, 32 mice in the tetrathiomolybdate alone group, 38 mice in the RT alone group, and 46 mice in the tetrathiomolybdate + RT group. Ceruloplasmin assays showed that we had obtained adequate copper reduction throughout the experiments to inhibit angiogenesis with minimal toxic effects. The tetrathiomolybdate + RT combined therapy group of mice showed a statistically significant decrease in tumor growth compared with both the tetrathiomolybdate alone (P = .001) and RT alone groups (P<.001). CONCLUSION: The combination of the anti-angiogenic copper chelating agent tetrathiomolybdate with RT improved local control of HNSCC in an isogenic mouse model compared with either therapy alone.

Design Considerations for Developing Hyperbranched Polyglycerol Nanoparticles as Systemic Drug Carriers.

PEGylation is commonly used to increase the plasma residence time of anticancer drug nanocarriers. However, PEGylation may trigger antibody production and lead to accelerated blood clearance in subsequent administrations. Moreover, the presence of PEG shells on nanocarriers may also hamper endosomal escape and decrease drug payload release. To avoid these shortcomings, we synthesized and evaluated a non-PEGylated, hyperbranched polyglycerol nanoparticle (HPG NP) with a hydrophobic core and a hydrophilic HPG shell, HPG-C10-HPG, as a candidate for systemic delivery of anticancer drug. In vitro studies with primary human cell lines revealed that HPG-C10-HPG possesses low cytotoxicity. The presence of long chain alkyl groups (C1o) in the core as the hydrophobic pocket in the NP enabled the binding and sustained release of the hydrophobic drug docetaxel. Remarkably, the docetaxel-loaded HPG-C10-HPG formulation also confers preferential protection to primary cells, when compared to cancer cells, potentially widening the therapeutic index. HPG-C10-HPG, however, accumulated at higher levels in the liver and spleen when administered intravenously in mice. Comparing the biodistribution patterns of HPG-C10-HPG, PEGylated HPG-C10-PEG, and unmodified HPG in a xenograft model reveals that the accumulation pattern of HPG-C10-HPG was attributed to insufficient shielding of the hydrophobic groups by the HPG shell. Our results revealed the influence of the nature of the hydrophilic shell and the presence of hydrophobic groups on the tumor-to-tissue accumulation specificities of these HPG NP variants. Therefore, the present study provides insights into the structural considerations of future HPG NP designs for systemic drug delivery.

In vivo biodistribution of dendrimers and dendrimer nanocomposites -- implications for cancer imaging and therapy.

Our results indicate that the surface chemistry, composition, and 3-D structure of nanoparticles are critical in determining their in vivo biodistribution, and therefore the efficacy of nanodevice imaging and therapies. We demonstrate that gold/dendrimer nanocomposites in vivo, present biodistribution characteristics different from PAMAM dendrimers in a B16 mouse tumor model system. We review important chemical and biologic uses of these nanodevices and discuss the potential of nanocomposite devices to greatly improve cancer imaging and therapy, in particular radiation therapy. We also discuss major issues confronting the use of nanoparticles in the near future, with consideration of toxicity analysis and whether biodegradable devices are needed or even desirable.

Radiotherapy and antiangiogenic TM in lung cancer.

Tetrathiomolybdate (TM) is a potent nontoxic orally delivered copper complexing agent under development for the last several years for the treatment of Wilson's disease. It has been shown to block angiogenesis in primary and metastatic tumors. Therefore, the combination of cytotoxic radiotherapy (RT) and antiangiogenic TM could target both the existing tumor and the tumor microvasculature in a comprehensive strategy. Using a Lewis lung high metastatic (LLHM) carcinoma mouse tumor model, we demonstrate that the combination of TM and RT is more effective than either used as monotherapy. We also show that their therapeutic effects are additive, with no additional toxicity. We show that TM has no significant cytotoxicity in vitro against LLHM tumor cells, further supporting the antiangiogenic mechanism for its action.

In vivo toxicity evaluation of gold-dendrimer composite nanodevices with different surface charges.

Composite nanodevices (CNDs) are multifunctional nanomaterials with potential uses in cancer imaging and therapy. Poly(amidoamine) dendrimer-based composite nanodevices are important members of this group and consist of an organic dendrimer component and an incorporated inorganic component, in this case, gold. This study addresses the short- (14 days) and long-term (78 days) in vivo toxicity of generation-5 (G5; 5 nm) PAMAM dendrimer-based gold-CNDs (Au-CNDs) with varying surface charges (positive, negative and neutral) in C57BL/6J male mice. Detailed toxicological analyses of (1) body weight changes, (2) serum chemistry and (3) histopathological examination of 22 organs showed no evidence of organ injury or organ function compromise. Zeta potential of Au-CNDs showed significant change from their parent dendrimers upon gold incorporation, making the normally lethal positive surface dendrimer biologically safe. Also homeostatic mechanisms in vivo may compensate/repair toxic effects, something not seen with in vitro assays.

Pretreatment nutritional status and locoregional failure of patients with head and neck cancer undergoing definitive concurrent chemoradiation therapy.

BACKGROUND: This study was carried out to determine if markers of nutritional status predict for locoregional failure following intensity-modulated radiation therapy (IMRT) with concurrent chemoradiotherapy (CCRT) for squamous cell carcinoma of the head and neck (SCCHN). METHODS: We performed a retrospective chart review of 78 patients with SCCHN who received definitive CCRT. We compared patient factors, tumor characteristics, and nutritional status indicators between patients with and without locoregional failure. RESULTS: Fifteen of 78 patients (19%) experienced locoregional failure. Median follow-up for live patients was 38 months. On univariate analysis, pretreatment percentage of ideal body weight (%IBW) (p < .01), pretreatment hemoglobin (p = .04), and treatment duration (p < .01) were significant predictors of failure. On multivariate analysis, pretreatment %IBW (p = .04) and treatment time (p < .01) remained statistically significant. CONCLUSIONS: Although treatment time is an accepted risk factor for failure, differences in outcome for patients with head and neck cancer undergoing definitive CCRT based on pretreatment %IBW should be examined further.

Radiation treatment interruptions greater than one week and low hemoglobin levels (12 g/dL) are predictors of local regional failure after definitive concurrent chemotherapy and intensity-modulated radiation therapy for squamous cell carcinoma of the head and neck.

PURPOSE: To determine whether baseline hemoglobin level and radiation treatment interruptions predict for loco-regional failure after intensity-modulated radiation therapy (IMRT) with concurrent chemotherapy for definitive treatment of squamous cell carcinoma of the head and neck (SCCHN). METHODS: This retrospective review identified 78 consecutive patients treated with definitive concurrent chemoradiation for SCCHN. Patients were treated with IMRT to 70 Gy in 35 daily fractions to the high-dose target volume and 56 Gy to the elective target volume. RESULTS: Median age of the cohort was 62 (37-81). Median follow-up was 12 months. Tumor sites included: oropharynx (54%), larynx (36%), oral cavity (5%), and hypopharynx (5%). Fifteen of 78 patients (19%) experienced loco-regional failure. These included: 6 primary site failures, 5 regional failures, and 4 failures in both the primary site and regional lymph nodes. All but one failure occurred in the high-dose target volume. Only duration of radiation treatment and baseline hemoglobin levels were significant predictors of local control. Loco-regional failure occurred in 6 of 13 patients (46%) with radiation treatment interruptions (>1 week) versus 9 of 65 patients (14%) completing radiation therapy without interruption (P = 0.0148). Loco-regional failure occurred in 7 of 19 patients (37%) whose pretreatment hemoglobin level was <12 g/dL compared with 8 of 59 patients (14%) with hemoglobin levels > or = 12 (P = 0.042). CONCLUSION: Overall radiation treatment time and pretreatment hemoglobin level were significant predictors for loco-regional failure after definitive concurrent chemotherapy and IMRT for SCCHN.

Synthesis and characterization of PAMAM dendrimer-based multifunctional nanodevices for targeting alphavbeta3 integrins.

We have synthesized a stable and clinically relevant nanodevice (cRGD-BT-ND; ND for short) that exhibits superior binding to the biologic target alphavbeta3 integrins, when either compared to the same free cRGD peptide or to the biotinylated nanodevice without covalently attached peptides (BT-ND). Selective targeting of alphavbeta3 integrins was achieved by coupling cyclic cRGD peptides to the nanodevice (ND) surface, while biotin groups (BT) were used for amplified detection of bound cRGD-BT-ND by anti-biotin antibody or avidin linked to horseradish peroxidase after binding. The synthesis involved the following steps: the amino-terminated ethylenediamine core generation 5 poly(amidoamine) (PAMAM_E5.NH2) dendrimer was first partially acetylated and then biotinylated, and residual primary amine termini were converted to succinamic acid groups (SAH), some of which finally were conjugated with cRGD peptide residues through the amino group of the lysine side chain. The starting material and all derivatives were extensively characterized by polyacrylamide gel electrophoresis (PAGE), size exclusion chromatography (SEC), potentiometric acid-base titration, MALDI-TOF, and NMR. Cytotoxicity of all dendrimer derivatives was examined in B16F10 melanoma cell cultures using the XTT colorimetric assay for cellular viability. Binding of nanodevices to the biological target was determined using plates coated with human alphavbeta3 integrin and alphavbeta3 receptor expressing human dermal microvascular endothelial cells (HDMECs). The PAMAM_E5.(NHAc)72(NHBT)8(NHSAH)35(NHSA-cR GD)4 nanodevice is nontoxic within physiologic concentration ranges and specifically binds to the alphavbeta3 integrins, apparently much stronger than the cyclic cRGD peptide itself.

E-selectin is required for the antiangiogenic activity of endostatin.

Endostatin, a 20-kDa fragment of collagen XVIII, is a potent angiogenesis inhibitor. E-selectin, an inducible leukocyte adhesion molecule specifically expressed by endothelial cells, has also been implicated in angiogenesis. By using in vivo, ex vivo, and in vitro angiogenic assays, we investigated the functional relationship between endostatin and E-selectin. In corneal micropocket assays, recombinant endostatin administered i.p. by osmotic pump inhibited basic fibroblast growth factor-induced angiogenesis in WT, but not E-selectin-deficient, mice. Similarly, endostatin inhibited vascular endothelial growth factor-stimulated endothelial sprout formation from aortic rings dissected from WT but not from E-selectin-deficient mice. To further explore this apparent requirement for E-selectin in endostatin action, we manipulated E-selectin expression in cultured human endothelial cells. When E-selectin was induced by IL-1beta, or lipopolysaccharide, human umbilical vein endothelial cells and human dermal microvascular endothelial cells each became markedly more sensitive to inhibition by endostatin in a vascular endothelial growth factor-induced cell migration assay. To dissociate E-selectin expression from other consequences of endothelial activation, human umbilical vein endothelial cells were transduced with an adenoviral human E-selectin expression construct; these cells also showed increased sensitivity to endostatin, and this effect required the E-selectin cytoplasmic domain. Taken together, these results indicate that E-selectin is required for the antiangiogenic activity of endostatin in vivo and ex vivo and confers endostatin sensitivity to nonresponsive human endothelial cells in vitro. E-selectin may be a useful predictor and modulator of endostatin efficacy in antiangiogenic therapy.

3H dendrimer nanoparticle organ/tumor distribution.

PURPOSE: To determine the in vivo biodistribution for differently charged poly(amidoamine) (PAMAM) dendrimers in B16 melanoma and DU145 human prostate cancer mouse tumor model systems. METHODS: Neutral (NSD) and positive surface charged (PSD) generation 5 (d = 5 nm) PAMAM dendrimers were synthesized by using 3H-labeled acetic anhydride and tested in vivo. Dendrimer derivatives were injected intravenously, and their biodistribution was determined via liquid scintillation counting of tritium in tissue and excretory samples. Mice were also monitored for acute toxicity. RESULTS: Both PSD and NSD localized to major organs and tumor. Dendrimers cleared rapidly from blood, with deposition peaking at 1 h for most organs and stabilizing from 24 h to 7 days postinjection. Maximal excretion occurred via urine within 24 h postinjection. Neither dendrimer showed acute toxicity. CONCLUSIONS: Changes in the net surface charge of polycationic PAMAMs modify their biodistribution. PSD deposition into tissues is higher than NSD, although the biodistribution trend is similar. Highest levels were found in lungs, liver, and kidney, followed by those in tumor, heart, pancreas, and spleen, while lowest levels were found in brain. These nanoparticles could have future utility as systemic biomedical delivery devices.