Two-Stage SN38 Release from a Core-Shell Nanoparticle Enhances Tumor Deposition and Antitumor Efficacy for Synergistic Combination with Immune Checkpoint Blockade.

Long-circulating nanomedicines efficiently deliver chemotherapies to tumors to reduce general toxicity. However, extended blood circulation of nanomedicines can increase drug exposure to leukocytes and lead to hematological toxicity. Here, we report a two-stage release strategy to enhance the drug deposition and antitumor efficacy of OxPt/SN38 core-shell nanoparticles with a hydrophilic oxaliplatin (OxPt) prodrug coordination polymer core and a lipid shell containing a hydrophobic cholesterol-conjugated SN38 prodrug (Chol-SN38). By conjugating cholesterol to the phenol group of SN38 via an acetal linkage and protecting the 20-hydroxy position with a trimethylsilyl (TMS) group, Chol-SN38 releases SN38 in two stages via esterase-catalyzed cleavage of the acetal linkage in the liver followed by acid-mediated hydrolysis of the TMS group to preferentially release SN38 in tumors. Compared to irinotecan, OxPt/SN38 reduces SN38 blood exposure by 9.0 times and increases SN38 tumor exposure by 4.7 times. As a result, OxPt/SN38 inhibits tumor growth on subcutaneous, spontaneous, and metastatic tumor models by causing apoptotic and immunogenic cell death. OxPt/SN38 exhibits strong synergy with the immune checkpoint blockade to regress subcutaneous colorectal and pancreatic tumors with 33-50% cure rates and greatly inhibits tumor growth and invasion in a spontaneous prostate cancer model and a liver metastasis model of colorectal cancer without causing side effects. Mechanistic studies revealed important roles of enhanced immunogenic cell death and upregulated PD-L1 expression by OxPt/SN38 in activating the tumor immune microenvironment to elicit potent antitumor immunity. This work highlights the potential of combining innovative prodrug design and nanomedicine formulation to address unmet needs in cancer therapy.

Human-Induced Neural and Mesenchymal Stem Cell Therapy Combined with a Curcumin Nanoconjugate as a Spinal Cord Injury Treatment.

We currently lack effective treatments for the devastating loss of neural function associated with spinal cord injury (SCI). In this study, we evaluated a combination therapy comprising human neural stem cells derived from induced pluripotent stem cells (iPSC-NSC), human mesenchymal stem cells (MSC), and a pH-responsive polyacetal-curcumin nanoconjugate (PA-C) that allows the sustained release of curcumin. In vitro analysis demonstrated that PA-C treatment protected iPSC-NSC from oxidative damage in vitro, while MSC co-culture prevented lipopolysaccharide-induced activation of nuclear factor-κB (NF-κB) in iPSC-NSC. Then, we evaluated the combination of PA-C delivery into the intrathecal space in a rat model of contusive SCI with stem cell transplantation. While we failed to observe significant improvements in locomotor function (BBB scale) in treated animals, histological analysis revealed that PA-C-treated or PA-C and iPSC-NSC + MSC-treated animals displayed significantly smaller scars, while PA-C and iPSC-NSC + MSC treatment induced the preservation of ß-III Tubulin-positive axons. iPSC-NSC + MSC transplantation fostered the preservation of motoneurons and myelinated tracts, while PA-C treatment polarized microglia into an anti-inflammatory phenotype. Overall, the combination of stem cell transplantation and PA-C treatment confers higher neuroprotective effects compared to individual treatments.

"Smart" polymer enhances the efficacy of topical antimicrobial agents.

The delivery of antimicrobial agents to surface wounds has been shown to be of central importance to the wound healing process. In this work, we prepared film forming wound care formulations containing 3 polymers (FTP) that provide broad-spectrum antimicrobial protection for prolonged periods. FTP formulations comprises of a smart gel matrix comprising of pH-degradable and temperature responsive polyacetals (smart polymer) which allow for the FTP films to be hydrophobic at room temperature, preventing accidental rubbing off, and hydrophilic at lower temperatures, allowing for easy removal. Two FTP smart-antimicrobial films were evaluated in this work: FTP-AgSD (Silver sulfadiazine actives), and FTP-NP (Neosporin actives). The in vitro and ex vivo antimicrobial efficacy studies show that FTP-AgSD films are significantly more effective for longer durations against Staphylococcus aureus (3 days), Candida albicans (9 days) and Pseudomonas aeruginosa (4 days) when compared to the cream formulations containing antimicrobials. FTP-NP films showed significantly improved antimicrobial activity for a minimum of 3 days for all pathogens tested. Moreover, when tested ex vivo in porcine skin, FTP-AgSD and FTP-NP showed average improvements of 0.89 log10 and 1.66 log10 respectively over standard cream counterparts. Dermal toxicity studies were carried out in a rat skin excision model which showed a similar wound healing pattern to that in rats treated with standard cream formulations as represented by reduction in wound size, and increase in wound healing markers.

HIF-1α inhibition by diethylstilbestrol and its polyacetal conjugate in hypoxic prostate tumour cells: insights from NMR metabolomics.

In this study, we have employed 1H NMR metabolomics to assess the metabolic responses of PC3 prostate tumour cells to hypoxia and to pharmacological HIF-1α inhibition by DES or its polyacetal conjugate tert-DES. Oxygen deprivation prompted a number of changes in intracellular composition and metabolic activity, mainly reflecting upregulated glycolysis, amino acid catabolism and other compensatory mechanisms used by hypoxic cells to deal with oxidative imbalance and energy deficit. Cell treatment with a non-cytotoxic concentration of DES, under hypoxia, triggered significant changes in 17 metabolites. Among these, lactate, phosphocreatine and reduced glutathione, whose levels showed opposite variations in hypoxic and drug-treated cells, emerged as possible markers of DES-induced HIF-1α inhibition. Furthermore, the free drug had a much higher impact on the cellular metabolome than tert-DES, particularly concerning polyamine and pyrimidine biosynthetic pathways, known to be tightly involved in cell proliferation and growth. This is likely due to the different cell pharmacokinetics observed between free and conjugated DES. Overall, this study has revealed a number of unanticipated metabolic changes that inform on DES and tert-DES direct cellular effects, providing further insight into their mode of action at the biochemical level.

Malaria-infected mice live until at least day 30 after a new artemisinin-derived thioacetal thiocarbonate combined with mefloquine are administered together in a single, low, oral dose.

In only three steps and in 21-67% overall yields from the natural trioxane artemisinin, a series of 21 new trioxane C-10 thioacetals was prepared. Upon receiving a single oral dose of only 6 mg/kg of the monomeric trioxane 12c combined with 18 mg/kg of mefloquine hydrochloride, Plasmodium berghei-infected mice survived on average 29.8 days after infection. Two of the four mice in this group had no parasites detectable in their blood on day 30 after infection, and they behaved normally and appeared healthy. One of the mice had 11% blood parasitemia on day 30, and one mouse in this group died on day 29. Of high medicinal importance, the efficacy of this ACT chemotherapy is much better than (almost double) the efficacy under the same conditions using as a positive control the popular trioxane drug artemether plus mefloquine hydrochloride (average survival time of only 16.5 days).

Antihyperglycaemic activity of 2,4:3,5-dibenzylidene-D-xylose-diethyl dithioacetal in diabetic mice.

We have recently generated lipophilic D-xylose derivatives that increase the rate of glucose uptake in cultured skeletal muscle cells in an AMP-activated protein kinase (AMPK)-dependent manner. The derivative 2,4:3,5-dibenzylidene-D-xylose-diethyl dithioacetal (EH-36) stimulated the rate of glucose transport by increasing the abundance of glucose transporter-4 in the plasma membrane of cultured myotubes. The present study aimed at investigating potential antihyperglycaemic effects of EH-36 in animal models of diabetes. Two animal models were treated subcutaneously with EH-36: streptozotocin-induced diabetes in C57BL/6 mice (a model of insulin-deficient type 1 diabetes), and spontaneously diabetic KKAy mice (Kuo Kondo rats carrying the A(y) yellow obese gene; insulin-resistant type 2 diabetes). The in vivo biodistribution of glucose in control and treated mice was followed with the glucose analogue 2-deoxy-2-[(18) F]-D-glucose; the rate of glucose uptake in excised soleus muscles was measured with [(3) H]-2-deoxy-D-glucose. Pharmacokinetic parameters were determined by non-compartmental analysis of the in vivo data. The effective blood EH-36 concentration in treated animals was 2 µM. It reduced significantly the blood glucose levels in both types of diabetic mice and also corrected the typical compensatory hyperinsulinaemia of KKAy mice. EH-36 markedly increased glucose transport in vivo into skeletal muscle and heart, but not to adipose tissue. This stimulatory effect was mediated by Thr(172) -phosphorylation in AMPK. Biochemical tests in treated animals and acute toxicological examinations showed that EH-36 was well tolerated and not toxic to the mice. These findings indicate that EH-36 is a promising prototype molecule for the development of novel antidiabetic drugs.

Chemotherapy of leishmaniasis Part VI: synthesis and bioevaluation of some novel terpenyl S,N- and N,N-acetals.

Some novel terpene based oxoketene S,N-acetals 2(a-g) and N,N-acetals 3(a-c) have been synthesized from oxoketene dithioacetal 1. The compounds were screened for their in vivo antileishmanial activity. Some of the compounds showed 50-70% inhibition in the hamster model.

Comparison of L-758,298, a prodrug for the selective neurokinin-1 antagonist, L-754,030, with ondansetron for the prevention of cisplatin-induced emesis.

Substance P is localised in brainstem regions associated with emesis. Based on studies in the ferret, it was postulated that a neurokinin-1 (NK1) receptor antagonist would have antiemetic activity as monotherapy in humans receiving chemotherapy. L-758,298 is a water-soluble, intravenous (i.v.) prodrug for L-754,030, a potent and selective NK1 receptor antagonist. This double-blind, randomised, active-agent (ondansetron)-controlled study enrolled 53 cisplatin-naïve patients and evaluated the prevention of both acute (0-24 h) and delayed (days 2-7) emesis after cisplatin treatment (50-100 mg/m(2)). All patients received i.v. L-758,298 (60 or 100 mg) (n=30) or ondansetron (32 mg) (n=23) before cisplatin and efficacy was evaluated up to day 7 post-cisplatin. Nausea was assessed by means of a four-point ordinal scale at intervals over the 7 day period. In the acute period, the proportion of patients without emesis in the L-758,298 and ondansetron groups was 37 and 52%, respectively (no significant difference between the groups). Comparing the distribution of average nausea scores over the entire first 24 h revealed no significant difference between the groups. In the delayed period, the proportion of patients without emesis in the L-758,298 and ondansetron treatment groups was 72 and 30%, respectively (P=0.005). The distribution of average nausea scores in the delayed period was lower in the L-758,298 group compared with the ondansetron group (P=0.15 for the entire delayed period and P=0.043 for day 2 only). No serious adverse events were attributed to L-758,298. A single dose of L-758,298 substantially suppressed the delayed nausea and vomiting characteristic of high dose cisplatin and also appeared to reduce acute emesis post-cisplatin. The data also support the proposition that the underlying mechanism(s) of acute and delayed emesis are different.

Reduction of cisplatin-induced emesis by a selective neurokinin-1-receptor antagonist. L-754,030 Antiemetic Trials Group.

BACKGROUND: The localization of substance P in brain-stem regions associated with vomiting, and the results of studies in ferrets, led us to postulate that a neurokinin-1-receptor antagonist would be an antiemetic in patients receiving anticancer chemotherapy. METHODS: In a multicenter, double-blind, placebo-controlled trial involving 159 patients who had not previously received cisplatin, we evaluated the prevention of acute emesis (occurring within 24 hours) and delayed emesis (on days 2 to 5) after a single dose of cisplatin therapy (70 mg or more per square meter of body-surface area). Before receiving cisplatin, all the patients received granisetron (10 microg per kilogram of body weight intravenously) and dexamethasone (20 mg orally). The patients were randomly assigned to one of three treatments in addition to granisetron and dexamethasone: 400 mg of an oral trisubstituted morpholine acetal (also known as L-754,030) before cisplatin and 300 mg on days 2 to 5 (group 1), 400 mg of L-754,030 before cisplatin and placebo on days 2 to 5 (group 2), or placebo before cisplatin and placebo on days 2 to 5 (group 3). Additional medication was available at any time to treat occurrences of vomiting or nausea. RESULTS: In the acute-emesis phase, 93 percent of the patients in groups 1 and 2 combined and 67 percent of those in group 3 had no vomiting (P<0.001). In the delayed-emesis phase, 82 percent of the patients in group 1, 78 percent of those in group 2, and 33 percent of those in group 3 had no vomiting (P<0.001 for the comparison between group 1 or 2 and group 3). The median nausea score in the delayed-emesis phase was significantly lower in group 1 than in group 3 (P=0.003). No serious adverse events were attributed to L-754,030. CONCLUSIONS: The neurokinin-1-receptor antagonist L-754,030 prevents delayed emesis after treatment with cisplatin. Moreover, combining L-754,030 with granisetron plus dexamethasone improves the prevention of acute emesis.

[Efficacy of alcoholates and clay in percutaneous contamination of rats with highly toxic organophosphorus compounds]. / Efikasnost alkoholata i gline kod perkutane kontaminacije pacova visoko toksicnim organofosfornim jedinjenjima.

Efficacy of decontamination by alcoholate and clay has been examined in animals percutaneously poisoned by nerve war gases (VX, soman) and organophosphorous insecticides (parathion, dichlorvos, terbufos) at exposure of 2, 5 and 60 minutes. High efficacy was achieved after two minutes using alcoholates which, except for VX, was lower for 50% after 5 minutes. The similar results were also achieved with clay in nerve war gas poisoning, however, the efficacy of this material was somewhat lower. By delayed decontamination (after 60 minutes) in animals poisoned by parathion and terbufos somewhat lower but still satisfying efficacy was achieved (ZI = 3.3, that is, 11.5). The results obtained have shown that efficacy of decontamination, except for the used materials, depends also on duration of the procedure.

Biodegradable polymers in controlled drug delivery.

Erosion mechanisms are divided into three types and drug release within each type is described. Type I erosion involves hydrolysis of hydrogels and these are useful in the controlled release of macromolecules entangled within their network structure. Type II erosion involves solubilization of water-insoluble polymers by reactions involving groups pendant from the polymer backbone. Of particular interest are polymers that solubilize by ionization of carboxylic acid groups, and the utilization of those systems is described. Type III erosion involves cleavage of hydrolytically labile bonds within the polymer backbone and four distinct polymer systems within this category are under development. One system involves the diffusion of drugs from a reservoir through a bioerodible membrane, another system utilizes microcapsules, a third system utilizes monolithic devices, and the fourth system utilizes drugs chemically bound to a bioerodible polymer.

PIP: Controlled-release methodologies can be classified on the basis of the mechanism that controls the release of the active agent from the delivery device diffusion, osmosis, or polymer erosion. This paper presents an extensive review of the research on erosional devices. The various polymer erosion mechanisms are of 3 basic types. Type I erosion refers to water-soluble polymers that have been insolubilized by covalent cross-links and that solubilize as the cross-links (type IA) or backbone (type IB) undergo a hydrolytic cleavage. In type II erosion, polymers that are initially water insoluble are solubilized by hydrolysis, ionization, or pronation of a pendant group. In type III erosion, hydrophobic polymers are converted to small water-soluble molecules by backbone cleavage. The choice of a particular erosion mechanism is dictated by the specific application. In addition, there are 2 mechanisms of polymer release from bioerodible polymers: one approach involves surrounding the drug core with a rate-controlling bioerodible membrane, while the other involves dispersing the drug within a polymer to form a bioerodible monolithic device. The use of biodegradable systems for the sustained release of fertility-regulating agents is based on type III erosion. Polymer erosion tends to lead drug release, and there is some indication that drug release from the implant is controlled by rate of solubilization of the highly water-insoluble steroid.

Studies on cyclophosphamide metabolites and their related compounds. 2. Preparation of an active species of cyclophosphamide and related compounds.

A synthetic study was made on the active metabolite of cyclophosphamide. Ozonolysis of O-(3 butenyl)-N,N-bis(2-chloroethyl)phosphorodiamidate, prepared by reaction of POC13 with 3-buten-1-ol followed by treatment with N,N-bis(2-chloroethyl)amine (nor mustard) and NH3, afforded 2-[bis(2-chloroethyl)amino]-4-hydroperoxytetrahydro-2H-1, 3,2-oxazaphosphorine 2-oxide (4-hydroperoxycyclophosphamide). Deoxygenation of 4-hydroperoxycyclophosphamide by triphenylphosphine yielded 4-hydroxycyclophosphamide in a pure crystalline state. These products exhibited high cytostatic activity in both in vitro and in vivo experiments. The results give confirmatory evidence for the hypothesis that C4-hydroxylation on the 1,3,2-oxazaphosphorinane ring of cyclophosphamide is necessary for its activation.

Antiparasitic nitroimidazoles. 8. Derivatives of 2-(4-formylstyryl)-5-nitro-1-vinylimidazole.

A series of 33 thioacetals and hydrazones of 2-(4-formylstyryl)-5-nitro-1-vinylimidazole was prepared and examined for antitrypanosomal properties. The thioacetals were inactive as antitrypanosomal agents but three hydrazones derived from N-aminoguanidine, pyridylacethohydrazide chloride (Girard reagent P), and dimethylaminoacetohydrazide (Girard reagent D) displayed good activity against Trypanosoma rhodesiense.