Anticancer therapeutics employing RNA interference mechanism holds promising potentials for sequence-specific silencing of target genes. However targeted delivery of siRNAs to tumor tissues and cells and more importantly, their intracellular release at sites of interest still remains a major challenge that needs to be addressed before this technique could become a clinically viable option. In the current study, we have engineered and screened a series of CD44 targeting hyaluronic acid (HA) based self-assembling nanosystems for targeted siRNA delivery. The HA polymer was functionalized with lipids of varying carbon chain lengths/nitrogen content, as well as polyamines for assessing siRNA encapsulation. From the screens, several HA-derivatives were identified that could stably encapsulate/complex siRNAs and form self-assembled nanosystems, as determined by gel retardation assays and dynamic light scattering. Many HA derivatives could transfect siRNAs into cancer cells overexpressing CD44 receptors. Interestingly, blocking the CD44 receptors on the cells using free excess soluble HA prior to incubation of cy3-labeled-siRNA loaded HA nano-assemblies resulted in >90% inhibition of the receptor mediated uptake, confirming target specificity. In addition, SSB/PLK1 siRNA encapsulated in HA-PEI/PEG nanosystems demonstrated dose dependent and target specific gene knockdown in both sensitive and resistant A549 lung cancer cells overexpressing CD44 receptors. More importantly, these siRNA encapsulated nanosystems demonstrated tumor selective uptake and target specific gene knock down in vivo in solid tumors as well as in metastatic tumors. The HA based nanosystems thus portend to be promising siRNA delivery vectors for systemic targeting of CD44 overexpressing cancers including tumor initiating (stem-) cells and metastatic lesions.

BackgroundNumerous clinical trials have demonstrated that oncolytic viruses can elicit antitumor responses when they are administered directly into localized cancers. However, the treatment of metastatic disease with oncolytic viruses has been challenging due to the inactivation of viruses by components of human blood and/or to inadequate tumor selectivity.MethodsWe determined the cytolytic potential and selectivity of Seneca Valley Virus-001 (SVV-001), a newly discovered native picornavirus, in neuroendocrine and pediatric tumor cell lines and normal cells. Suitability of the virus for intravenous delivery in humans was assessed by blood inactivation assays. Safety was evaluated in vivo using an immune-competent mouse model, and efficacy was evaluated in vivo in athymic mice bearing tumors derived from human small-cell lung cancer and retinoblastoma cell lines.ResultsCell lines derived from small-cell lung cancers and solid pediatric cancers were at least 10000-fold more sensitive to the cytolytic activity of SVV-001 than were any of the adult normal human cells tested. Viral infectivity was not inhibited by human blood components. Intravenous doses up to 1 × 1014 virus particles (vp) per kg were well tolerated, and no dose-limiting toxicity was observed in immune-competent mice. A single intravenous dose of 1 × 108 vp per kg into athymic mice bearing preestablished small-cell lung or retinoblastoma tumors resulted in complete, durable responses in ten of ten and five of eight mice, respectively.ConclusionsSVV-001 has potent cytolytic activity and high selectivity for tumor cell lines having neuroendocrine properties versus adult normal cells. Systemically administered SVV-001 has potential for the treatment of metastatic neuroendocrine cancers.

Background-Barrett's oesophagus, columnar metaplasia of the epithelium, is a premalignant condition with a 50-100-fold increased risk of cancer. The condition is caused by chronic gastro-oesophageal reflux. Regression of metaplasia may decrease the cancer risk. Aims-To determine whether elimination of acid gastro-oesophageal reflux induces a regression of metaplastic epithelium. Methods-Sixty eight patients with acid reflux and proven Barrett's oesophagus were included in a prospective, randomised, double blind study with parallel groups, and were treated with profound acid secretion suppression with omeprazole 40 mg twice daily, or with mild acid secretion suppression with ranitidine 150 mg twice daily, for 24 months. Endoscopy was performed at 0, 3, 9, 15, and 24 months with measurement of length and surface area of Barrett's oesophagus; pH-metry was performed at 0 and 3 months. Per protocol analysis was performed on 26 patients treated with omeprazole, and 27 patients treated with ranitidine. Results-Omeprazole reduced reflux to 0.1%, ranitidine to 9.4% per 24 hours. Symptoms were ameliorated in both groups. There was a small, but statistically significant regression of Barrett's oesophagus in the omeprazole group, both in length and in area. No change was observed in the ranitidine group. The diVerence between the regression in the omeprazole and ranitidine group was statistically significant for the area of Barrett's oesophagus (p=0.02), and showed a trend in the same direction for the length of Barrett's oesophagus (p=0.06). Conclusions-Profound suppression of acid secretion, leading to elimination of acid reflux, induces partial regression of Barrett's oesophagus. (Gut 1999;45:489-494)

Purpose:The purpose of this study was to examine the tumor specificity, cytotoxicity, and granulocyte macrophage colony-stimulating factor expression of CG0070, a conditionally replicating oncolytic adenovirus, in human bladder transitional cell carcinoma (TCC) cell lines and determine its antitumor efficacy in bladderTCC tumor models. Experimental Design: Virus yield and cytotoxicity assays were used to determine tumor specificity and virus replication-mediated cytotoxicity of CG0070 in a panel of human bladderTCC cell lines and primary cells in vitro. Two s.c. and one orthotopic bladderTCC xenograft tumor models were used to assess antitumor activity of CG0070. Results: In a matched isogenic pair of cell lines with differing retinoblastoma (Rb) pathway status, CG0070 showed selective E1a and granulocyte macrophage colony-stimulating factor (GM-CSF) expression in Rb pathway^defective cells. CG0070 replicated in Rb-defective bladderTCC cell lines as efficiently as wild-type adenovirus but produced 100-fold less virus in normal human cells. CG0070 was up to 1,000-fold more cytotoxic in Rb pathway^defective bladder TCC cells in comparison with normal human cells. Antitumor activity of CG0070 was shown in two bladder TCC s.c. xenograft tumor models following intratumoral injections and intravesical treatment in an orthotopic xenograft tumor model when compared with PBS treatment. Conclusions: In vitro and in vivo studies showed the selective replication, cytotoxicity, GM-CSF production, and antitumor efficacy of CG0070 in several bladder TCC models, suggesting a potential utility of this oncolytic agent for the treatment of bladder cancer. Further studies are warranted to show the role of human GM-CSF in the antitumor efficacy of CG0070.

Multidrug resistance (MDR) is a significant problem in the clinical management of several cancers. Overcoming MDR generally involves multi-modal therapeutic approaches that integrates enhancement of delivery efficiency using targeted nano-platforms as well as strategies that can sensitize cancer cells to drug treatments. We recently demonstrated that tandem delivery of siRNAs that downregulate anti-apoptotic genes overexpressed in cisplatin resistant tumors followed by therapeutic challenge using cisplatin loaded in CD44 targeted hyaluronic acid (HA) nanoparticles (NPs) induced synergistic antitumor response in CD44 expressing tumors that are resistant to cisplatin. In the current study, a near infrared (NIR) dye-loaded HA NPs was employed to image the whole body localization of NPs after intravenous (i.v.) injection into live mice bearing human lung tumors that were sensitive and resistant to cisplatin. In addition, we quantified the siRNA duplexes and cisplatin dose distribution in various tissues and organs using an ultra-sensitive quantitative PCR method and inductively coupled plasma-mass spectrometry (ICP-MS), respectively, after i.v. injection of the payload loaded HA NPs in tumor bearing mice. Our findings demonstrate that the distribution pattern of the siRNA and cisplatin using specifically engineered CD44 targeting HA NPs correlated well with the tumor targeting capability as well as the activity and efficacy obtained with combination treatments.

One of the most challenging aspects of lung cancer therapy is the rapid acquisition of multidrug-resistant (MDR) phenotype. One effective approach would be to identify and downregulate resistance-causing genes in tumors using small interfering RNAs (siRNAs) to increase the sensitivity of tumor cells to chemotherapeutic challenge. After identifying the overexpressed resistance-related antiapoptotic genes (survivin and bcl-2) in cisplatin-resistant cells, the siRNA sequences were designed and screened to select the most efficacious candidates. Modifications were introduced in them to minimize off-target effects. Subsequently, the combination of siRNA and cisplatin that gave the maximum synergy was identified in resistant cells. We then demonstrated that the combination treatment of the selected siRNAs and cisplatin encapsulated in CD44-targeting hyaluronic acid (HA)-based self-assembling nanosystems reversed the resistance to cisplatin and delayed the tumor growth significantly (growth inhibition increased from 30 to 60%) in cisplatin-resistant tumors. In addition, no abnormalities in body weights, liver enzyme levels or histopathology of liver/spleen tissues were observed in any of the treatment groups during the study period. Overall, we demonstrate that the combination of siRNA-mediated gene-silencing strategy with chemotherapeutic agents constitutes a valuable and safe approach for the treatment of MDR tumors.

Gutless adenoviral vectors are devoid of all viral coding regions and display reduced cytotoxicity, diminished immunogenicity, and an increased coding capacity compared with early generation vectors. Using hemophilia A, a deficiency in clotting factor VIII (FVIII), as a model disease, we generated and evaluated a gutless vector encoding human FVIII. The FVIII gutless vector grew to high titer and was reproducibly scaled-up from vector seed lots. Extensive viral DNA analyses revealed no rearrangements of the vector genome. A quantitative PCR assay demonstrated helper virus contamination levels of <2%, with the best preparation containing 0.3% helper virus. We compared the gutless vector with an E1/E2a/E3-deficient (Av3) early generation vector encoding an identical FVIII expression cassette following intravenous administration to hemophilia A mice. Gutless vector-treated mice displayed 10-fold higher FVIII expression levels that were sustained for at least 9 months. In contrast, mice treated with the Av3 vector displayed FVIII levels below the limit of sensitivity of the assay at 3 months. Assessment of hepatotoxicity by measuring the serum levels of liver enzymes demonstrated that the gutless vector was significantly less toxic than the Av3 vector at time points later than 7 days. At the highest dose used, both vectors caused a transient 10-fold increase in liver enzymes 1 day after vector administration, suggesting that this increase was caused by direct toxicity of the input capsid proteins. These data demonstrate that the gutless vector displayed increased duration and levels of FVIII expression, and was significantly less toxic than an analogous early generation vector.

The distinct protein corona fingerprint on lipid nanoparticles of different surface characteristics affected cellular transfection and gene silencing.