Impact of formulation on the iontophoretic delivery of the FOLFIRINOX regimen for the treatment of pancreatic cancer.

PURPOSE: Effective treatment of patients with locally advanced pancreatic cancer is a significant unmet clinical need. One major hurdle that exists is inadequate drug delivery due to the desmoplastic stroma and poor vascularization that is characteristic of pancreatic cancer. The local iontophoretic delivery of chemotherapies provides a novel way of improving treatment. With the growing practice of highly toxic combination therapies in the treatment of pancreatic cancer, the use of iontophoresis for local delivery can potentiate the anti-cancer effects of these therapies while sparing unwanted toxicity. The objective of this study was to investigate the impact of formulation on the electro-transport of the FOLFIRINOX regimen for the development of a new treatment for pancreatic cancer. METHODS: Three formulations of the FOLFIRINOX regimen (5-fluorouracil, leucovorin, irinotecan, and oxaliplatin) were generated at a fixed pH of 6.0 and were referred to as formulation A (single drug solution with all four drugs combined), formulation B (two drug solutions with two drugs per solution), and formulation C (four individual drug solutions). Anodic iontophoresis of the three different formulations was evaluated in orthotopic patient-derived xenografts of pancreatic cancer. RESULTS: Iontophoretic transport of the FOLFIRINOX drugs was characterized according to organ exposure after a single device treatment in vivo. We report that the co-iontophoresis of two drug solutions, leucovorin + oxaliplatin and 5-fluorouracil + irinotecan, resulted in the highest levels of cytotoxic drugs in the tumor compared to drugs delivered individually or combined into one solution. There was no significant difference in plasma, pancreas, kidney, and liver exposure to the cytotoxic drugs delivered by the three different formulations. In addition, we found that reducing the duration of iontophoretic treatment from 10 to 5 min per solution resulted in a significant decrease in drug concentrations. CONCLUSIONS: Underlying the difference in drug transport of the formulations was electrolyte concentrations, which includes both active and inactive components. Electrolyte concentrations can hinder or improve drug electro-transport. Overall, balancing electrolyte concentration is needed for optimal electro-transport.

Local iontophoretic administration of cytotoxic therapies to solid tumors.

Parenteral and oral routes have been the traditional methods of administering cytotoxic agents to cancer patients. Unfortunately, the maximum potential effect of these cytotoxic agents has been limited because of systemic toxicity and poor tumor perfusion. In an attempt to improve the efficacy of cytotoxic agents while mitigating their side effects, we have developed modalities for the localized iontophoretic delivery of cytotoxic agents. These iontophoretic devices were designed to be implanted proximal to the tumor with external control of power and drug flow. Three distinct orthotopic mouse models of cancer and a canine model were evaluated for device efficacy and toxicity. Orthotopic patient-derived pancreatic cancer xenografts treated biweekly with gemcitabine via the device for 7 weeks experienced a mean log2 fold change in tumor volume of -0.8 compared to a mean log2 fold change in tumor volume of 1.1 for intravenous (IV) gemcitabine, 3.0 for IV saline, and 2.6 for device saline groups. The weekly coadministration of systemic cisplatin therapy and transdermal device cisplatin therapy significantly increased tumor growth inhibition and doubled the survival in two aggressive orthotopic models of breast cancer. The addition of radiotherapy to this treatment further extended survival. Device delivery of gemcitabine in dogs resulted in more than 7-fold difference in local drug concentrations and 25-fold lower systemic drug levels than the IV treatment. Overall, these devices have potential paradigm shifting implications for the treatment of pancreatic, breast, and other solid tumors.

Rapidly-dissolvable microneedle patches via a highly scalable and reproducible soft lithography approach.

Microneedle devices for transdermal drug delivery have recently become an attractive method to overcome the diffusion-limiting epidermis and effectively transport therapeutics to the body. Here, we demonstrate the fabrication of highly reproducible and completely dissolvable polymer microneedles on flexible water-soluble substrates. These biocompatible microneedles (made by using a soft lithography process known as PRINT) showed efficacy in piercing both murine and human skin samples and delivering a fluorescent drug surrogate to the tissue.

Microfabricated curtains for controlled cell seeding in high throughput microfluidic systems.

A microfabricated cell curtain is presented that facilitates cellular assays. The cell curtain is defined as a poly(dimethylsiloxane) (PDMS) wall that extends from the ceiling of a cell culture microchamber to within microns of the chamber floor. Curtain use is demonstrated by observing monolayer human epidermal keratinocyte (HEK) colonies for 48 h longer than possible with non-curtained microfluidic chambers. The curtains were further characterized by integrating them into a 96 chamber high throughput microfluidic cell culture device. As proof of concept, this device was used to assay a range of ethanol dilutions spanning 0-22% in cell culture medium. Cells exposed to 12% ethanol or less for 30 min would recover to 85% viability at 24 h, while cells exposed to higher concentrations had viabilities below 10%. The data also showed that cells exposed to 6% ethanol or less grew in population size, 8% ethanol exposure stunted growth, and higher concentrations led to population loss. Curtain use permitted high initial cell seeding densities and increased the amount of time cells can be cultured compared to multi-well plates.

Characterization of microfluidic human epidermal keratinocyte culture.

Human epidermal keratinocytes (HEK) are skin cells of primary importance in maintaining the body's defensive barrier and are used in vitro to assess the irritation potential and toxicity of chemical compounds. Microfluidic systems hold promise for high throughput irritant and toxicity assays, but HEK growth kinetics have yet to be characterized within microscale culture chambers. This research demonstrates HEK patterning on microscale patches of Type I collagen within microfluidic channels and maintenance of these cells under constant medium perfusion for 72 h. HEK were shown to maintain 93.0%-99.6% viability at 72 h under medium perfusion ranging from 0.025-0.4 mul min(-1). HEK maintained this viability while approximately 100% confluent-a level not possible in 96 well plates. Microscale HEK cultures offer the ability to precisely examine the morphology, behavior and viability of individual cells which may open the door to new discoveries in toxicological screening methods and wound healing techniques.

A linear dilution microfluidic device for cytotoxicity assays.

A two-layer polymer microfluidic device is presented which creates nine linear dilutions from two input fluid streams mixed in varying volumetric proportions. The linearity of the nine dilutions is conserved when the flow rate is held constant at 1.0 microl min(-1) (R(2) = 0.9995) and when it is varied from 0.5-16 microl min(-1) (R(2) = 0.9998). An analytical expression is presented for designing microfluidic devices with arbitrary numbers of linear dilutions. To demonstrate the efficacy of this device, primary human epidermal keratinocytes (HEK) were stained with nine dilutions of calcein, resulting in a linear spread of fluorescent intensities (R(2) = 0.94). The operating principles of the device can be scaled up to incorporate any number of linear dilutions. This scalability, coupled with an intrinsic ability to create linear dilutions under a variety of operating conditions, makes the device applicable to high throughput screening applications such as combinatorial chemistry or cytotoxicity assays.

A serial dilution microfluidic device for cytotoxicity assays.

A novel microfluidic device is presented which creates a linear serial dilution of two input fluid streams. This platform facilitates higher productivity as a component of a high throughput cytotoxicity testing strategy. A modeling solution is presented to create custom linear dilution schemes. The featured device creates a serial dilution of two solutions in the range of 1:9 through 9:1 across nine discrete dilutions. It has been validated to create a highly linear progression of dilutions with an R2 value of 0.9993. The device functions equivalently over a wide range of flow rates. The standard deviation of dilution values averages 0.76% over six flow rates spanning 0.5 to 16 microl min(-1).