Targeted Doxorubicin Delivery to Brain Tumors via Minicells: Proof of Principle Using Dogs with Spontaneously Occurring Tumors as a Model

BACKGROUND: Cytotoxic chemotherapy can be very effective for the treatment of cancer but toxicity on normal tissues often limits patient tolerance and often causes long-term adverse effects. The objective of this study was to assist in the preclinical development of using modified, non-living bacterially-derived minicells to deliver the potent chemotherapeutic doxorubicin via epidermal growth factor receptor (EGFR) targeting. Specifically, this study sought to evaluate the safety and efficacy of EGFR targeted, doxorubicin loaded minicells (designated EGFRminicellsDox) to deliver doxorubicin to spontaneous brain tumors in 17 companion dogs; a comparative oncology model of human brain cancers. METHODOLOGY/PRINCIPLE FINDINGS: EGFRminicellsDox were administered weekly via intravenous injection to 17 dogs with late-stage brain cancers. Biodistribution was assessed using single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI). Anti-tumor response was determined using MRI, and blood samples were subject to toxicology (hematology, biochemistry) and inflammatory marker analysis. Targeted, doxorubicin-loaded minicells rapidly localized to the core of brain tumors. Complete resolution or marked tumor regression (>90% reduction in tumor volume) were observed in 23.53% of the cohort, with lasting anti-tumor responses characterized by remission in three dogs for more than two years. The median overall survival was 264 days (range 49 to 973). No adverse clinical, hematological or biochemical effects were observed with repeated administration of EGFRminicellsDox (30 to 98 doses administered in 10 of the 17 dogs). CONCLUSIONS/SIGNIFICANCE: Targeted minicells loaded with doxorubicin were safely administered to dogs with late stage brain cancer and clinical activity was observed. These findings demonstrate the strong potential for clinical applications of targeted, doxorubicin-loaded minicells for the effective treatment of patients with brain cancer. On this basis, we have designed a Phase 1 clinical study of EGFR-targeted, doxorubicin-loaded minicells for effective treatment of human patients with recurrent glioblastoma

Implementing statically typed object-oriented programming languages

A paraîtreInternational audienceObject-oriented programming languages represent an original implementation issue due to the mechanism known as late binding, aka message sending. The underlying principle is that the address of the actually called procedure is not statically determined, at compile-time, but depends on the dynamic type of a distinguished parameter known as the receiver. In statically typed languages, the point is that the receiver's dynamic type may be a subtype of its static type. A similar issue arises with attributes, because their position in the object layout may depends on the object's dynamic type. Furthermore, subtyping introduces another original feature, i.e. subtype checks. All three mechanisms need specific implementations, data structures and algorithms. In statically typed languages, late binding is generally implemented with tables, called virtual function tables in C++ jargon. These tables reduce method calls to pointers to functions, through a small fixed number of extra indirections. It follows that object-oriented programming yields some overhead, as compared to usual procedural languages. The different techniques and their resulting overhead depend on several parameters. Firstly, inheritance and subtyping may be single or multiple and a mixing is even possible, as in JAVA, which presents single inheritance for classes and multiple subtyping for interfaces. Multiple inheritance is a well known complication. Secondly, the production of executable programs may involve various schemes, from global compilation frameworks, where the whole program is known at compile time, to separate compilation and dynamic loading, where each program unit---usually a class in an object-oriented context---is compiled and loaded independently of any usage. Global compilation is well known to facilitate optimization. In this paper, we review the various implementation schemes available in the context of static typing and in the three cases of single inheritance, multiple inheritance, and single inheritance but with multiple subtyping, e.g. JAVA. The survey focuses on separate compilation and dynamic loading, as it is the most commonly used framework and the most demanding. However, many works have been recently undertaken in the global compilation framework, mostly for dynamically typed languages but also applied to the EIFFEL language in the SMARTEIFFEL compiler. Hence, we examine global techniques and how they can improve implementation efficiency. Finally, a mixed framework is considered, where separate compilation is followed by a global step, similar to linking, which uses global techniques, as well for implementation, with coloring, as for optimization, with type analysis. An application to dynamic loading is sketched

Sequential treatment of drug-resistant tumors with targeted minicells containing siRNA or a cytotoxic drug

The dose-limiting toxicity of chemotherapeutics, heterogeneity and drug resistance of cancer cells, and difficulties of targeted delivery to tumors all pose daunting challenges to effective cancer therapy. We report that small interfering RNA (siRNA) duplexes readily penetrate intact bacterially derived minicells previously shown to cause tumor stabilization and regression when packaged with chemotherapeutics. When targeted via antibodies to tumor-cell-surface receptors, minicells can specifically and sequentially deliver to tumor xenografts first siRNAs or short hairpin RNA (shRNA)-encoding plasmids to compromise drug resistance by knocking down a multidrug resistance protein. Subsequent administration of targeted minicells containing cytotoxic drugs eliminate formerly drug-resistant tumors. The two waves of treatment, involving minicells loaded with both types of payload, enable complete survival without toxicity in mice with tumor xenografts, while involving several thousandfold less drug, siRNA and antibody than needed for conventional systemic administration of cancer therapies