Nanoparticle delivery of chemotherapy combination regimen improves the therapeutic efficacy in mouse models of lung cancer.

The combination chemotherapy regimen of cisplatin (CP) and docetaxel (DTX) is effective against a variety of cancers. However, combination therapies present unique challenges that can complicate clinical application, such as increases in toxicity and imprecise exposure of tumors to specific drug ratios that can produce treatment resistance. Drug co-encapsulation within a single nanoparticle (NP) formulation can overcome these challenges and further improve combinations' therapeutic index. In this report, we employ a CP prodrug (CPP) strategy to formulate poly(lactic-co-glycolic acid)-poly(ethylene glycol) (PLGA-PEG) NPs carrying both CPP and DTX. The dually loaded NPs display differences in drug release kinetics and in vitro cytotoxicity based on the structure of the chosen CPP. Furthermore, NPs containing both drugs showed a significant improvement in treatment efficacy versus the free drug combination in vivo.

Effect of particle size on the biodistribution, toxicity, and efficacy of drug-loaded polymeric nanoparticles in chemoradiotherapy.

Nanoparticle (NP) chemotherapeutics can improve the therapeutic index of chemoradiotherapy (CRT). However, the effect of NP physical properties, such particle size, on CRT is unknown. To address this, we examined the effects of NP size on biodistribution, efficacy and toxicity in CRT. PEG-PLGA NPs (50, 100, 150 nm mean diameters) encapsulating wotrmannin (wtmn) or KU50019 were formulated. These NP formulations were potent radiosensitizers in vitro in HT29, SW480, and lovo rectal cancer lines. In vivo, the smallest particles avoided hepatic and splenic accumulation while more homogeneously penetrating tumor xenografts than larger particles. However, smaller particles were no more effective in vivo. Instead, there was a trend toward enhanced efficacy with medium sized NPs. The smallest KU60019 particles caused more small bowel toxicity than larger particles. Our results showed that particle size significantly affects nanotherapeutics' biodistrubtion and toxicity but does not support the conclusion that smaller particles are better for this clinical application.

An additional substrate binding site in a bacterial phenylalanine hydroxylase.

Phenylalanine hydroxylase (PAH) is a non-heme iron enzyme that catalyzes oxidation of phenylalanine to tyrosine, a reaction that must be kept under tight regulatory control. Mammalian PAH has a regulatory domain in which binding of the substrate leads to allosteric activation of the enzyme. However, the existence of PAH regulation in evolutionarily distant organisms, for example some bacteria in which it occurs, has so far been underappreciated. In an attempt to crystallographically characterize substrate binding by PAH from Chromobacterium violaceum, a single-domain monomeric enzyme, electron density for phenylalanine was observed at a distal site 15.7 Å from the active site. Isothermal titration calorimetry (ITC) experiments revealed a dissociation constant of 24 ± 1.1 µM for phenylalanine. Under the same conditions, ITC revealed no detectable binding for alanine, tyrosine, or isoleucine, indicating the distal site may be selective for phenylalanine. Point mutations of amino acid residues in the distal site that contact phenylalanine (F258A, Y155A, T254A) led to impaired binding, consistent with the presence of distal site binding in solution. Although kinetic analysis revealed that the distal site mutants suffer discernible loss of their catalytic activity, X-ray crystallographic analysis of Y155A and F258A, the two mutants with the most noticeable decrease in activity, revealed no discernible change in the structure of their active sites, suggesting that the effect of distal binding may result from protein dynamics in solution.

Heart rate and autonomic biomarkers distinguish convulsive epileptic vs. functional or dissociative seizures.

OBJECTIVE: 20-40% of individuals whose seizures are not controlled by anti-seizure medications exhibit manifestations comparable to epileptic seizures (ES), but there are no EEG correlates. These events are called functional or dissociative seizures (FDS). Due to limited access to EEG-monitoring and inconclusive results, we aimed to develop an alternative diagnostic tool that distinguishes ES vs. FDS. We evaluated the temporal evolution of ECG-based measures of autonomic function (heart rate variability, HRV) to determine whether they distinguish ES vs. FDS. METHODS: The prospective study includes patients admitted to the University of Rochester Epilepsy Monitoring Unit. Participants are 18-65 years old, without therapies or co-morbidities associated with altered autonomics. A habitual ES or FDS is recorded during admission. HRV analysis is performed to evaluate the temporal changes in autonomic function during the peri­ictal period (150-minutes each pre-/post-ictal). We determined if autonomic measures distinguish ES vs. FDS. RESULTS: The study includes 53 ES and 46 FDS. Temporal evolution of HR and autonomics significantly differ surrounding ES vs. FDS. The pre-to-post-ictal change (delta) in HR differs surrounding ES vs. FDS, stratified for convulsive and non-convulsive events. Post-ictal HR, total autonomic (SDNN & Total Power), vagal (RMSSD & HF), and baroreflex (LF) function differ for convulsive ES vs. convulsive FDS. HR distinguishes non-convulsive ES vs. non-convulsive FDS with ROC>0.7, sensitivity>70%, but specificity<50%. HR-delta and post-ictal HR, SDNN, RMSSD, LF, HF, and Total Power each distinguish convulsive ES vs. convulsive FDS (ROC, 0.83-0.98). Models with HR-delta and post-ictal HR provide the highest diagnostic accuracy for convulsive ES vs. convulsive FDS: 92% sensitivity, 94% specificity, ROC 0.99). SIGNIFICANCE: HR and HRV measures accurately distinguish convulsive, but not non-convulsive, events (ES vs. FDS). Results establish the framework for future studies to apply this diagnostic tool to more heterogeneous populations, and on out-of-hospital recordings, particularly for populations without access to epilepsy monitoring units.

3D printed drug-loaded implantable devices for intraoperative treatment of cancer.

Surgery is an important treatment for cancer; however, local recurrence following macroscopically-complete resection is common and a significant cause of morbidity and mortality. Systemic chemotherapy is often employed as an adjuvant therapy to prevent recurrence of residual disease, but has limited efficacy due to poor penetration and dose-limiting off-target toxicities. Selective delivery of chemotherapeutics to the surgical bed may eliminate residual tumor cells while avoiding systemic toxicity. While this is challenging for traditional drug delivery technologies, we utilized advances in 3D printing and drug delivery science to engineer a drug-loaded arrowhead array device (AAD) to overcome these challenges. We demonstrated that such a device can be designed, fabricated, and implanted intraoperatively and provide extended release of chemotherapeutics directly to the resection area. Using paclitaxel and cisplatin as model drugs and murine models of cancer, we showed AADs significantly decreased local recurrence post-surgery and improved survival. We further demonstrated the potential for fabricating personalized AADs for intraoperative application in the clinical setting.

Preclinical Evaluation of Promitil, a Radiation-Responsive Liposomal Formulation of Mitomycin C Prodrug, in Chemoradiotherapy.

PURPOSE: To examine the effect of radiation on in vitro drug activation and release of Promitil, a pegylated liposomal formulation of a mitomycin C (MMC) lipid-based prodrug; and examine the efficacy and toxicity of Promitil with concurrent radiation in colorectal cancer models. METHODS AND MATERIALS: Promitil was obtained from Lipomedix Pharmaceuticals (Jerusalem, Israel). We tested the effects of radiation on release of active MMC from Promitil in vitro. We next examined the radiosensitization effect of Promitil in vitro. We further evaluated the toxicity of a single injection of free MMC or Promitil when combined with radiation by assessing the effects on blood counts and in-field skin and hair toxicity. Finally, we compared the efficacy of MMC and Promitil in chemoradiotherapy using mouse xenograft models. RESULTS: Mitomycin C was activated and released from Promitil in a controlled-release profile, and the rate of release was significantly increased in medium from previously irradiated cells. Both Promitil and MMC potently radiosensitized HT-29 cells in vitro. Toxicity of MMC (8.4 mg/kg) was substantially greater than with equivalent doses of Promitil (30 mg/kg). Mice treated with human-equivalent doses of MMC (3.3 mg/kg) experienced comparable levels of toxicity as Promitil-treated mice at 30 mg/kg. Promitil improved the antitumor efficacy of 5-fluorouracil-based chemoradiotherapy in mouse xenograft models of colorectal cancer, while equitoxic doses of MMC did not. CONCLUSIONS: We demonstrated that Promitil is an attractive agent for chemoradiotherapy because it demonstrates a radiation-triggered release of active drug. We further demonstrated that Promitil is a well-tolerated and potent radiosensitizer at doses not achievable with free MMC. These results support clinical investigations using Promitil in chemoradiotherapy.

Improving DNA double-strand repair inhibitor KU55933 therapeutic index in cancer radiotherapy using nanoparticle drug delivery.

Radiotherapy is a key component of cancer treatment. Because of its importance, there has been high interest in developing agents and strategies to further improve the therapeutic index of radiotherapy. DNA double-strand repair inhibitors (DSBRIs) are among the most promising agents to improve radiotherapy. However, their clinical translation has been limited by their potential toxicity to normal tissue. Recent advances in nanomedicine offer an opportunity to overcome this limitation. In this study, we aim to demonstrate the proof of principle by developing and evaluating nanoparticle (NP) formulations of KU55933, a DSBRI. We engineered a NP formulation of KU55933 using nanoprecipitation method with different lipid polymer nanoparticle formulation. NP KU55933 using PLGA formulation has the best loading efficacy as well as prolonged drug release profile. We demonstrated that NP KU55933 is a potent radiosensitizer in vitro using clonogenic assay and is more effective as a radiosensitizer than free KU55933 in vivo using mouse xenograft models of non-small cell lung cancer (NSCLC). Western blots and immunofluorescence showed NP KU55933 exhibited more prolonged inhibition of DNA repair pathway. In addition, NP KU55933 leads to lower skin toxicity than KU55933. Our study supports further investigations using NP to deliver DSBRIs to improve cancer radiotherapy treatment.

Nanoparticle formulations of histone deacetylase inhibitors for effective chemoradiotherapy in solid tumors.

Histone deacetylase inhibitors (HDACIs) represent a class of promising agents that can improve radiotherapy in cancer treatment. However, the full therapeutic potential of HDACIs as radiosensitizers has been restricted by limited efficacy in solid malignancies. In this study, we report the development of nanoparticle (NP) formulations of HDACIs that overcome these limitations, illustrating their utility to improve the therapeutic ratio of the clinically established first generation HDACI vorinostat and a novel second generation HDACI quisinostat. We demonstrate that NP HDACIs are potent radiosensitizers in vitro and are more effective as radiosensitizers than small molecule HDACIs in vivo using mouse xenograft models of colorectal and prostate carcinomas. We found that NP HDACIs enhance the response of tumor cells to radiation through the prolongation of γ-H2AX foci. Our work illustrates an effective method for improving cancer radiotherapy treatment.

Nanoparticle delivery of chemosensitizers improve chemotherapy efficacy without incurring additional toxicity.

Chemosensitizers can improve the therapeutic index of chemotherapy and overcome treatment resistance. Successful translation of chemosensitizers depends on the development of strategies that can preferentially deliver chemosensitizers to tumors while avoiding normal tissue. We hypothesized that nanoparticle (NP) formulation of chemosensitizers can improve their delivery to tumors which can in turn improve their therapeutic index. To demonstrate the proof of principle of this approach, we engineered NP formulations of two chemosensitizers, the PI3-kindase inhibitor wortmanin (Wtmn) and the PARP inhibitor olaparib. NP Wtmn and NP olaparib were evaluated as chemosensitizers using lung cancer cells and breast cancer cells respectively. We found Wtmn to be an efficient chemosensitizer in all tested lung-cancer cell lines reducing tumor cell growth between 20 and 60% compared to drug alone. NP formulation did not decrease its efficacy in vitro. Olaparib showed less consistent chemosensitization as a free drug or in NP formulation. NP Wtmn was further evaluated as a chemosensitizer using mouse models of lung cancer. We found that NP Wtmn is an effective chemosensitizer and more effective than free Wtmn showing a 32% reduction in tumor growth compared to free Wtmn when given with etoposide. Importantly, NP Wtmn was able to sensitize the multi-drug resistant H69AR cells to etoposide. Additionally, the combination of NP Wtmn and etoposide chemotherapy did not significantly increase toxicity. The present study demonstrates the proof of principle of using NP formulation of chemosensitizing drugs to improve the therapeutic index of chemotherapy.