Fine-tuning thermoresponsive functional poly(ε-caprolactone)s to enhance micelle stability and drug loading.

Block copolymers synthesized by the ring-opening polymerization of γ-2-[2-(2-methoxyethoxy)ethoxy]ethoxy-ε-caprolactone (ME3CL), γ-2-methoxyethoxy-ε-caprolactone (ME1CL), and ε-caprolactone (CL) are reported. Previously, diblock copolymers of PME3CL-b-PME1CL displayed excellent thermoresponsive tunability (31-43 °C) and self-assembled into micelles with moderate thermodynamic stability. In this report, two strategies are employed to enhance thermodynamic stability of PME3CL/PME1CL-type block copolymer micelles while maintaining their attractive thermoresponsive qualities: modification of the end group position and alteration of hydrophobic block composition by using both ME1CL and CL. These new thermoresponsive amphiphilic block copolymers showed lower critical micelle concentration (CMC) values by one order of magnitude and formed thermodynamically stable micelles. Furthermore they demonstrated good biocompatibility and up to 4.97 wt% doxorubicin loading, more than double the amount loaded into the PME3CL-type polymeric micelles previously reported.

Systematic repurposing screening in xenograft models identifies approved drugs with novel anti-cancer activity.

Approved drugs target approximately 400 different mechanisms of action, of which as few as 60 are currently used as anti-cancer therapies. Given that on average it takes 10-15 years for a new cancer therapeutic to be approved, and the recent success of drug repurposing for agents such as thalidomide, we hypothesized that effective, safe cancer treatments may be found by testing approved drugs in new therapeutic settings. Here, we report in-vivo testing of a broad compound collection in cancer xenograft models. Using 182 compounds that target 125 unique target mechanisms, we identified 3 drugs that displayed reproducible activity in combination with the chemotherapeutic temozolomide. Candidate drugs appear effective at dose equivalents that exceed current prescription levels, suggesting that additional pre-clinical efforts will be needed before these drugs can be tested for efficacy in clinical trials. In total, we suggest drug repurposing is a relatively resource-intensive method that can identify approved medicines with a narrow margin of anti-cancer activity.

Towards smart polymeric drug carriers: self-assembling γ-substituted polycaprolactones with highly tunable thermoresponsive behavior.

Synthesis and ring opening polymerization of a new γ-substituted ε-caprolactone monomer, γ-(2-methoxyethoxy)-ε-caprolactone is reported. Amphiphilic diblock copolymers comprised of poly[γ-(2-methoxyethoxy)-ε-caprolactone] and thermosensitive poly{γ-2-[2-(2-methoxyethoxy)ethoxy]ethoxy-ε-caprolactone} as the hydrophobic and hydrophilic blocks, respectively, were prepared. The copolymers exhibited fully biodegradable backbones and highly tunable thermoresponsive behavior in the range of 31-43 °C. Additionally, the copolymers were shown to self-assemble in aqueous media above their respective critical micelle concentrations, on the order of 10-2 g L-1. Due to their thermosensitive, self-assembling, and biodegradable properties, these copolymers demonstrate potential for the use in polymeric micellar drug delivery systems.