Pharmacokinetics of UGN-101, a mitomycin-containing reverse thermal gel instilled via retrograde catheter for the treatment of low-grade upper tract urothelial carcinoma.

PURPOSE: To evaluate the pharmacokinetic properties of UGN-101, a mitomycin-containing reverse thermal gel used as primary chemoablative treatment for low-grade upper tract urothelial carcinoma (UTUC), in a subset of patients participating in a phase 3 clinical trial. METHODS: Pharmacokinetic parameters (Cmax, Tmax, AUC(0-6), λz, t½, and AUCinf) were evaluated in six participants (male or female, ≥ 18 years) with biopsy-proven, low-grade UTUC who received the first of 6 once-weekly instillations of UGN-101 to the renal pelvis and calyces via retrograde ureteral catheter. Plasma samples were collected prior to instillation and 30 min, 1, 2, 3, 4, 5, and 6 h post-instillation. Safety was assessed by laboratory evaluations, physical exam, and adverse event monitoring. RESULTS: The mean age of the six participants was 69 years; most were male (5/6) and Caucasian (5/6). Mean (SD) Cmax was 6.24 (4.11) ng/mL and mean Tmax was 1.79 (1.89) hours after instillation. Mean apparent t½ following instillation was 1.27 (0.63) hours. Mean total systemic exposure to mitomycin up to 6 h post-instillation was 20.30 (19.69) ng h/mL. At 6 h post-instillation, mitomycin plasma concentrations of 5/6 participants were < 2 ng/mL. There were no clinically important adverse events or changes in laboratory values in any participant after a single instillation of UGN-101. CONCLUSION: The reverse thermal gel formulation of UGN-101 is associated with higher concentration and extended dwell time of mitomycin in contact with the urothelium of the upper urinary tract while limiting systemic absorption of mitomycin. REGISTRATION: NCT02793128; registered June 8, 2016.

Development of Promitil®, a lipidic prodrug of mitomycin c in PEGylated liposomes: From bench to bedside.

Several liposome products have been approved for the treatment of cancer. In all of them, the active agents are encapsulated in the liposome water phase passively or by transmembrane ion gradients. An alternative approach in liposomal drug delivery consists of chemically modifying drugs to form lipophilic prodrugs with strong association to the liposomal bilayer. Based on this approach, we synthesized a mitomycin c-derived lipidic prodrug (MLP) which is entrapped in the bilayer of PEGylated liposomes (PL-MLP, Promitil®), and activated by thiolytic cleavage. PL-MLP is stable in plasma with thiolytic activation of MLP occurring exclusively in tissues and is more effective and less toxic than conventional chemotherapy in various tumor models. PL-MLP has completed phase I clinical development where it has shown a favorable safety profile and a 3-fold reduction in toxicity as compared to free mitomycin c. Clinical and pharmacokinetic studies in patients with advanced colo-rectal carcinoma have indicated a significant rate of disease stabilization (39%) in this chemo-refractory population and significant prolongation of median survival in patients attaining stable disease (13.9 months) versus progressive disease patients (6.35 months). The pharmacokinetics of MLP was typically stealth with long T½ (~1 day), slow clearance and small volume of distribution. Interestingly, a longer T½, and slower clearance were both correlated with disease stabilization and longer survival. This association of pharmacokinetic parameters with patient outcome suggests that arrest of tumor growth is related to the enhanced tumor localization of long-circulating liposomes and highlights the importance of personalized pharmacokinetic evaluation in the clinical use of nanomedicines. Another important area where PL-MLP may have an added value is in chemoradiotherapy, where it has shown a strong radiosensitizing effect in animal models based on a unique mechanism of enhanced prodrug activation and encouraging results in early human testing.

Pharmacokinetics of mitomycin-c lipidic prodrug entrapped in liposomes and clinical correlations in metastatic colorectal cancer patients.

Background Pegylated liposomal (PL) mitomycin-c lipidic prodrug MLP) may be a useful agent in patients with metastatic colo-rectal carcinoma (CRC). We report here on the pharmacokinetics and clinical observations in a phase 1A/B study with PL-MLP. Methods Plasma levels of MLP were examined in 53 CRC patients, who received PL-MLP either as single agent or in combination with capecitabine and/or bevacizumab. MLP was determined by an HPLC-UV assay, and its pharmacokinetics was analyzed by noncompartmental methods. The correlation between clinical and pharmacokinetic parameters was statistically analyzed. Results PL-MLP was well tolerated with a good safety profile as previously reported. Stable Disease was reported in 15/36 (42%) of efficacy-evaluable patients. Median survival of stable disease patients (14.4 months) was significantly longer than of progressive disease patients (6.5 months) and non-evaluable patients (2.3 months). MLP pharmacokinetics was stealth-like with long T½ (~1 day), slow clearance, and small volume of distribution (Vd). The addition of capecitabine and/or bevacizumab did not have any apparent effect on the pharmacokinetics of MLP and clinical outcome. High baseline neutrophil count and CEA level were correlated with faster clearance, and larger Vd. Stable disease patients had longer T½ and slower clearance than other patients. T½ and clearance were significantly correlated with survival. Conclusions PL-MLP treatment results in a substantial rate of disease stabilization in metastatic CRC, and prolonged survival in patients achieving stable disease. The correlation of neutrophil count and CEA level with pharmacokinetic parameters of MLP is an unexpected finding that needs further investigation. The association of long T½ of MLP with stable disease and longer survival is consistent with an improved probability of disease control resulting from enhanced tumor localization of long-circulating liposomes and underscores the relevance of personalized pharmacokinetic evaluation in the use of nanomedicines.

Development of a high-precision bladder hyperthermic intracavitary chemotherapy device for bladder cancer and pharmacokinetic study.

BACKGROUND: Bladder hyperthermic intracavitary chemotherapy (HIVEC) has good effectiveness for bladder cancer, but conventional HIVEC systems lack precision and convenient application. To test the safety of a new HIVEC device (BR-TRG-II-type) in pigs and to perform a preliminary clinical trial in patients with bladder cancer. METHODS: This device was tested on six pigs to optimize the temperature and time parameters. Then, 165 patients (HIVEC after transurethral resection (TUR), n = 128; or HIVEC, n = 37) treated between December 2006 and December 2016 were recruited. Mitomycin C (MMC) was the chemotherapeutic agent. A serum pharmacokinetic study was performed. The primary endpoints were tumor recurrence, disease-free survival (DFS), and cumulative incidence rate (CIR) during follow-up. The adverse effects were graded. RESULTS: The animal experiment showed that 45 °C for 1 h was optimal. HIVEC was successful, with the infusion tube temperature stably controlled at about 45 °C, and outlet tube temperature of about 43 °C in all patients, for three sessions. Serum MMC levels gradually increased during HIVEC and decreased thereafter. The mean DFS was 39 ± 3.21 months (ranging from 8 to 78 months), and the DFS rate was 89.1% during follow-up. No adverse events occurred. CONCLUSION: The use of the BR-TRG-II-type HIVEC device is feasible for the treatment of bladder cancer. Future clinical trials in patients with different stages of bladder cancer will further confirm the clinical usefulness of this device. TRIAL REGISTRATION: chictr.org.cn: ChiCTR1900022099 (registered on Mar. 252,019). Retrospectively registered.

Effect of 2 Novel Sustained-release Drug Release Systems on Bleb Fibrosis: An In Vivo Trabeculectomy Study in a Rabbit Model.

PRECIS: Rabbit model studies suggested better morphology blebs with equal intraocular pressure (IOP) efficacy as a standard mitomycin C (MMC) trabeculectomy using a novel slow-release drug delivery antifibrotic system delivering small quantities of MMC and 5-fluorouracil (5-FU). PURPOSE: To evaluate 2 different concentrations of biodegradable poly(lactic-co-glycolic acid) (PLGA) system with 5-FU and MMC (ElutiGLASS) for their ability to reduce fibrosis and compare the results with standard trabeculectomy with MMC in a rabbit model. MATERIALS AND METHODS: New Zealand albino rabbits (19) were divided into 3 groups (A, B, C) and standard trabeculectomy operation was performed in the right eye of each rabbit.Group (A) had trabeculectomy with MMC (0.4 mg/mL) applied using a Weck cell sponge; (B) trabeculectomy with slow-release ElutiGLASS (0.23 mg, 5-FU/0.33 µg MMC released over 23 to 30 d); (C) trabeculectomy with rapid release ElutiGLASS (0.45 mg of 5-FU/0.65 µg MMC, released over 5 to 7 d). The rabbits were followed for 3 months before euthanasia. RESULTS: Bleb morphology, vascularity, and fibrosis were less pronounced in groups B and C when compared with group A at 3 months. Group B appears to have a lower and more diffuse bleb appearance compared with the other 2 groups with honeycomb appearance on both clinical examination and ultrasound biomicroscopy imaging with higher percentage of maintained bleb space (83%), less fibrosis than group A while maintaining the same low inflammation score as the other 2 groups on histology. At 3 months, the PLGA polymer had completely disappeared in all rabbits. There were no statistical differences in the degree of IOP reduction or histologic inflammation, among the 3 groups. CONCLUSIONS: We successfully created a sustained-release antifibrotic drug delivery system that delivered known dosage of the drugs at doses that are significantly lower than the current standard, and resulted in less fibrosis while maintaining a healthy bleb and equal reduction of IOP. TRANSLATIONAL RELEVANCE: These results are supportive of the antifibrotic effect of the slow-release drug delivery system used in conjunction with trabeculectomy, thus paving the way for human pilot studies to improve and simplify existing surgical techniques for filtering surgeries in glaucoma.

Isolated thoracic perfusion in lung metastases from breast cancer: a retrospective observational study.

The median overall survival of metastatic breast cancer (MBC) patients is still approximately 2 years. This is even lower in triple-negative breast cancer (TNBC) patients with concomitant lung metastases. These patients are often not suitable for surgery and not responsive to systemic chemotherapy. Isolated thoracic perfusion (ITP) followed by chemofiltration has been used for palliation in selected specialised centres. A retrospective observational study evaluating 162 MBC patients who underwent 407 ITP procedures was performed. The primary objective was the evaluation of the feasibility, safety, tolerability and efficacy of ITP in the complete cohort of 162 patients with LM from breast cancer. The secondary objective of the study was the evaluation of responses and median survivals in 43 TNBC patients with LM. In the 162 patients, ITP appeared safe and well tolerated with MST from LM diagnosis to death or last contact of 19.5 months. In the subgroup of patients treated with systemic chemotherapy followed by ITP at progression, the MST from LM diagnosis to death or last contact was 29 months. In the subgroup of TNBC patients treated with systemic chemotherapy followed by ITP at progression, the MST from LM diagnosis to death or last contact was 19 months (ITP overall response rate was 65.52%). ITP followed by chemofiltration could be adopted in the sequential palliation treatments of BC patients with LM in progression after systemic chemotherapy, especially with TNBC. The present data allow interesting considerations about tolerability and responses, but do not allow robust conclusions about survival.

Size-Dependent Transport and Cytotoxicity of Mitomycin-Gold Nanoparticle Conjugates in 2D and 3D Mammalian Cell Models.

This work aims at learning how the size of gold nanocarriers influences the transport of DNA-alkylating antitumoral drugs. For this purpose, we devised conjugates of mercaptoethylmitomycin C (MEMC), a DNA alkylating agent, with gold nanoparticles of different sizes (2, 5, and 14 nm), and studied how size affects drug cytotoxicity, tumor penetrability, cellular uptake, and intracellular localization using two-dimensional (2D) and three-dimensional (3D) cell models. We show that only small, 2 nm, nanoparticles can transport MEMC efficiently to the cell nucleus, whereas MEMC cell uptake is much lower when delivered by these small nanoparticles than with the larger ones. 3D cellular models showed that smaller nanoparticles can transport MEMC toward deeper areas of tumor spheroids as compared to larger nanoparticles. We discuss the insights of this work toward the efficient delivery of DNA-targeting drugs.

Enhanced taxane uptake into bladder tissues following co-administration with either mitomycin C, doxorubicin or gemcitabine: association to exfoliation processes.

OBJECTIVE: To investigate the effect of three anticancer drugs (mitomycin c (MMC), doxorubicin or gemcitabine) on bladder wall morphology and the uptake of paclitaxel or docetaxel following coadministration. The primary objective of this study was to measure the uptake of MMC, doxorubicin or gemcitabine with or without exposure of the tissue to amine terminated cationic nanoparticles (CNPs) and to investigate any possible exfoliation effects of the three drugs on intact bladder tissue. The secondary objective was to investigate the uptake of taxane drugs (docetaxel, DTX) and paclitaxel, (PTX) from surfactant micelle formulations in the presence of MMC, doxorubicin or gemcitabine. MATERIALS AND METHODS: Sections of fresh pig bladder tissue were incubated in Franz diffusion cells with the urothelial side exposed to solutions of doxorubicin, MMC and gemcitabine containing radioactive drug for 90 min. Some tissue samples were simultaneously exposed to each of the three drugs in combination with the surfactant micelle formulations of PTX (Taxol) or DTX (Taxotere). Tissue sections were then cryostat sectioned for drug quantitation by liquid scintillation counting or fixed for scanning electron microscopy and haematoxylin and eosin staining. RESULTS: All three drugs caused exfoliation of the urothelial layer of bladder tissues. Drug uptake studies showed that all three drugs effectively penetrated the lamina propria through to the muscular layer over a 2-h incubation and these levels were unaffected by pre-treatment with CNPs. The uptake levels of the taxane drugs PTX and DTX were significantly enhanced following simultaneous treatment of bladders with MMC, doxorubicin or gemcitabine. CONCLUSION: The exfoliation effects of MMC, doxorubicin and gemcitabine allow for good tissue penetration of these drugs with no additional effect from CNP treatment of bladders. The observed exfoliation effect of these amine-containing drugs probably arises from a cationic interaction with the mucus and urothelium cell layer in a manner similar to that previously reported for CNPs. These studies suggest that the lack of long-term clinical efficacy of these drugs may not arise from poor intravesical drug penetration but may result from a rapid diffusion of the drugs into the deeper vascularised muscular region with rapid drug clearance. The enhanced uptake of PTX or DTX following co-administration with MMC, doxorubicin or gemcitabine probably arises from the removal of the urothelial barrier by exfoliation allowing for improved taxane partitioning into superficial layers. These effects may allow for dual drug intravesical strategies offering greatly improved taxane uptake and potential additive drug effects for improved efficacy.

Pharmacokinetics of lipid-drug conjugates loaded into liposomes.

Drugs that are neither lipophilic nor suitable for encapsulation via remote loading procedures are generally characterized by low entrapment efficiencies and poor retention in liposomes. One approach to circumvent this problem consists in covalently linking a lipid to the drug molecule in order to permit its insertion into the vesicle membrane. The nature of the conjugated lipid and linker, as well as the composition of the liposomal bilayer were found to have a profound impact on the pharmacokinetic properties and biodistribution of the encapsulated drugs as well as on their biological activity. This contribution reviews the past and recent developments on liposomal lipid-drug conjugates, and discusses important issues related to their stability and in vivo performance. It also provides an overview of the data that were generated during the clinical assessment of these formulations. The marketing authorization of the immunomodulating compound mifamurtide in several countries as well as the promising results obtained with the lipid prodrug of mitomycin C suggest that carefully designed liposomal formulations of lipid-drug conjugates is a valid strategy to improve a drug's pharmacokinetic profile and with that its therapeutic index and/or efficacy.

Diminishing the side effect of mitomycin C by using pH-sensitive liposomes: in vitro characterization and in vivo pharmacokinetics.

INTRODUCTION: Mitomycin C is an anticancer antibiotic agent that has the potential for broad-spectrum use against several cancers, including mammary cancers. Because its half-life is 17 min after a 30 mg intravenous bolus administration, the suitability of mitomycin C for wide use in the clinical setting is limited. Based on tumor pathophysiology, pH-sensitive liposomes could provide better tumor-targeted effects. The aim of this study was to investigate the possibility of diminishing the side effect of mitomycin C by using pH-sensitive liposomes. MATERIALS AND METHODS: pH-sensitive liposomes was employed to deliver mitomycin C and evaluate the characterization, release behaviors, cytotoxicity, in vivo pharmacokinetics and biochemical assay. RESULTS: The results demonstrated that mitomycin C-loaded pH-sensitive liposomes had a particle diameter of 144.5±2.8 nm and an entrapment efficiency of 66.5%. The in vitro release study showed that the pH-sensitive liposome release percentages at pH 7.4 and pH 5.5 were approximately 47% and 93%, respectively. The cell viability of MCF-7 cells showed that both the solution and liposome group exhibited a concentration-dependent effect on cell viability. The MCF-7 cell uptake of pH-sensitive liposomes with a folate modification was higher which was indicated by an increased fluorescence intensity compared to that without a folate modification. The area under the concentration-time curve of mitomycin C-loaded pH-sensitive liposomes (18.82±0.51 µg·h/L) was significantly higher than that of the mitomycin C solution group (10.07±0.31 µg·h/L). The mean residence times of the mitomycin C-loaded and mitomycin C solution groups were 1.53±0.16 and 0.05 h, respectively. In addition, there was no significant difference in terms of Vss (p>0.05). Moreover, the half-life of pH-sensitive liposomes and the mitomycin C solution was 1.35±0.15 and 1.60±0.04 h, respectively. In terms of safety, mitomycin C-loaded pH-sensitive liposomes did not affect the platelet count and the levels of blood urea nitrogen and aspartate aminotransferase. CONCLUSION: The positive results of pH-sensitive liposomes demonstrated maintained the cytotoxicity and decrease the side effect.

Systemic Absorption of Mitomycin-C When Used in Pterygium Surgery.

PURPOSE: To determine whether scleral topical application of mitomycin-C (MMC) results in measurable plasma levels of systemic absorption. METHODS: The study comprised 27 patients who were treated with MMC 0.2 mg/mL (0.02%) for 60 seconds during pterygium surgery. Blood samples were taken 30 minutes after surgery and evaluated by the human plasma liquid chromatography tandem-mass spectrometry method to determine the presence of MMC. RESULTS: The amount of MMC in 27 samples tested was determined as below 0.25 ppb (ng/mL). CONCLUSIONS: In this study of 27 patients treated with topical application of MMC for pterygium surgery, there was no measurable evidence of systemic drug absorption. Although systemic absorption has been found with the use of larger quantities of MMC, there is an extremely low likelihood of systemic absorption or toxicity of MMC after pterygium surgery.

Mitomycin C hypoxic pelvic perfusion for unresectable recurrent rectal cancer: pharmacokinetic comparison of surgical and percutaneous techniques.

Patients with unresectable recurrent rectal cancer that progresses after standard and multi-modular treatments are candidates for hypoxic pelvic perfusion. Hypoxic pelvic perfusion can be performed using a surgical or percutaneous approach. The aim of this study was to examine whether the surgical and percutaneous approaches are comparable with respect to tumor drug exposure in the pelvis. A pharmacokinetic study was performed in 18 patients. Both the surgical and percutaneous procedures were performed using mitomycin C (MMC) at a dose of 25 mg/m2. The main parameter that was used to evaluate pelvic tumor drug exposure was the ratio of the areas under the MMC plasma concentration curves in the pelvis and the systemic compartment during the perfusion time (AUC0-20). The mean values ± SD for the ratios between the MMC AUC0-20 in the pelvic and systemic compartments were 14.38 ± 4.31 and 13.15 ± 4.26 for the surgical and percutaneous techniques, respectively (p = 0.53). This pharmacokinetic study demonstrated that the percutaneous approach for hypoxic pelvic perfusion did not statistically differ from the surgical approach. When perfusion must be repeated several times in the same patient, the percutaneous and surgical methods may be adopted interchangeably. CLINICALTRIALS. GOV IDENTIFIER: NCT01891552.

Inhibition of Monocyte Chemoattractant Protein 1 Prevents Conjunctival Fibrosis in an Experimental Model of Glaucoma Filtration Surgery.

Purpose: To evaluate the effect of treatment with monocyte chemoattractant protein-1 receptor inhibitor (MCP-Ri) to maintain bleb survival and prevent fibrosis in an experimental model of glaucoma filtration surgery (GFS). Methods: GFS was performed on one eye of C57/Bl6 mice (n = 36) that was treated with MCP-Ri, mitomycin-C (MMC), or vehicle at the time of surgery. Real-time polymerase chain reaction was used to evaluate conjunctival expression of monocyte chemoattractant protein-1 (MCP-1), TGFB1, TGFB2, collagen 1a1 (Col1a1), sparc (Sparc), and fibronectin at 2 and 7 days following surgery. Anterior segment slit-lamp examination, optical coherence tomography, and confocal microscopy were performed in vivo at day 14. Eyes were processed for immunohistochemical staining of F4/80, a monocyte-macrophage marker, at day 2. In vitro experiments were also performed to compare the effect of MMC, MCP-Ri, and vehicle on the viability of mouse Tenon's fibroblasts. Results: Treatment with MCP-Ri results in a greater reduction in the percentage of F4/80-positive cells in conjunctival blebs and lesser MCP-1 gene expression following experimental GFS than MMC or control. Both MMC and MCP-Ri reduced Col1a1 and Sparc expression, but not fibronectin. TGFB1 decreased with MCP-Ri but not MMC; MMC but not MCP-Ri reduced TGFB2. MMC and MCP-Ri treatment resulted in the preservation of bleb height at day 14, as compared to control. MCP-Ri was less toxic to mouse Tenon's fibroblasts in comparison with MMC. Conclusions: Targeting MCP-1 results in prolonged bleb survival following experimental GFS with less cellular toxicity as compared to MMC. MCP inhibition could provide a safer alternative to conventional antifibrotic adjunctive treatments in GFS.

Feasibility and safety of hyperthermic intraperitoneal chemotherapy using 5-fluorouracil combined with cisplatin and mitomycin C in patients undergoing gastrectomy for advanced gastric cancer.

BACKGROUND AND OBJECTIVES: We conducted a dose-finding study for 5-fluorouracil (5-FU) administered with cisplatin (CDDP) and mitomycin C (MMC) to find an improved regimen for hyperthermic intraperitoneal chemotherapy (HIPEC) for advanced gastric cancer (GC). METHODS: The appropriate HIPEC regimen previously determined in vitro was 5-FU (200 µg/mL), MMC (2 µg/mL), and CDDP (10 µg/mL) at hyperthermic conditions (42°C) for 30 min. This was a clinical study to determine the recommended dose of 5-FU in combination with MMC and CDDP at 42°C for 30 min and to evaluate HIPEC safety in patients at high risk of developing peritoneal metastases following GC surgery. RESULTS: Twelve patients were treated with surgery plus HIPEC using 5-FU at 0, 500, 750, and 1000 mg combined with MMC (10 mg) and CDDP (50 mg) in the perfusate (5 L). Dose-limiting toxicities did not develop until 1000 mg 5-FU was reached. Four patients experienced grade 1 or 2 adverse events. The recommended dose was 1000 mg 5-FU/5 L perfusate. Eight (66.7%) patients demonstrated no recurrence of peritoneal metastases; 5-year overall survival rate was 83.3%. CONCLUSION: Gastrectomy and HIPEC with MMC, CDDP, and 5-FU is feasible, safe, and may protect against peritoneal metastasis following surgery for advanced GC.

The Combination of PlGF Inhibition and MMC as a Novel Anti-Scarring Strategy for Glaucoma Filtration Surgery.

PURPOSE: The complementary effects of mitomycin-C (MMC) and anti-placental growth factor (PlGF) therapy were explored and compared to the combined administration of MMC and aflibercept. Additionally, the effect of PlGF (inhibition) on IOP was investigated, since aqueous PlGF is known to be upregulated in glaucoma patients. METHODS: In the trabeculectomy mouse model, intracameral injection(s) of the PlGF inhibitor (5D11D4) were compared to MMC or aflibercept and to the combination of both compounds. Treatment outcome was studied by bleb investigation and by Sirius Red staining. The effect of subconjunctival PlGF administration and topical 5D11D4 on IOP was investigated in normotensive mice and was compared to topical administration of latanoprost, the gold standard for IOP-lowering. RESULTS: Combination of MMC and 5D11D4 was able to significantly improve surgical outcome compared to monotherapy of MMC or 5D11D4 (n = 20; P < 0.001). Compared to combined treatment of MMC with aflibercept, the simultaneous administration of MMC and 5D11D4 was equally efficacious in improving surgical outcome (n = 15; P = 0.88). In normotensive mice, 5D11D4 was able to significantly reduce the IOP-elevation induced by PlGF (n = 10; P < 0.05), whereas no effect of 5D11D4 was seen in naive mice, which was in contrast to latanoprost. CONCLUSIONS: The current data suggest that application of MMC together with PlGF inhibition may have complementary effects in the improvement of surgical outcome and is equally efficacious as the combined treatment of MMC and aflibercept. Inhibition of PlGF also might open alternative perspectives as IOP-lowering strategy for glaucoma patients with increased aqueous PlGF levels.

Polymer-lipid hybrid nanoparticles synchronize pharmacokinetics of co-encapsulated doxorubicin-mitomycin C and enable their spatiotemporal co-delivery and local bioavailability in breast tumor.

UNLABELLED: Effective combination chemotherapy requires the delivery of drugs of synergism to tumor sites while sparing normal tissues. Herein we investigated whether coencapsulation of doxorubicin and mitomycin C within polymer-lipid hybrid nanoparticles (DMPLN) achieved this goal via ratiometric drugs in an orthotopic murine breast tumor model with nanocarrier-modified biodistribution, pharmacokinetics, local bioavailability and toxicity. Fluorescence imaging revealed quickened and extended tumor uptake but reduced cardiac accumulation of DMPLN. Quantitative drug analysis demonstrated prolonged systemic circulation, increased tumor accumulation and sustained synergistic ratios of doxorubicin and mitomycin C delivered by DMPLN over 24h. Higher levels of tumor cell apoptosis and reduced organ toxicity were obtained with DMPLN compared to free drug cocktails. DMPLN released DOX in tumors more efficiently than that from liposomal doxorubicin, as evidenced by a higher extent of the metabolite, doxorubicinol. These findings substantiate the importance of rational design of nanoparticles for synergistic drug combination therapy. FROM THE CLINICAL EDITOR: The treatment of cancer usually involves using combination chemotherapeutic agents. In adopting a nanomedicine approach, one can in theory design combination therapy consisting of drugs of synergistic activities, with the aim to target tumor specifically while minimizing systemic toxicity. The authors in this study provided evidence for this rational design by co-encapsulation of doxorubicin and mitomycin C within polymer-lipid hybrid nanoparticles (DMPLN) in a breast cancer model.

Targeting of pegylated liposomal mitomycin-C prodrug to the folate receptor of cancer cells: Intracellular activation and enhanced cytotoxicity.

Mitomycin C (MMC) is a powerful anti-bacterial, anti-fungal and anti-tumor antibiotic, often active against multidrug resistant cells. Despite a broad spectrum of antitumor activity, MMC clinical use is relatively limited due to its fast clearance and dose-limiting toxicity. To exploit the potential antitumor activity of MMC and reduce its toxicity we have previously developed a formulation of pegylated liposomes with a lipophilic prodrug of MMC (PL-MLP), activated by endogenous reducing agents which are abundant in the tumor cell environment in the form of different thiols. PL-MLP has minimal in vitro cytotoxicity unless reducing agents are added to the cell culture to activate the prodrug. In the present study, we hypothesized that targeting PL-MLP via folate receptors will facilitate intracellular activation of prodrug and enhance cytotoxic activity without added reducing agents. We grafted a lipophilic folate conjugate (folate-PEG(5000)-DSPE) to formulate folate targeted liposomes (FT-PL-MLP) and examined in vitro cell uptake and cytotoxic activity in cancer cell lines with high folate receptors (HiFR). 3H-cholesterol-hexadecyl ether (3H-Chol)-radiolabeled liposomes were prepared to study liposome-cell binding in parallel to cellular uptake of prodrug MLP. 3H-Chol and MLP cell uptake levels were 4-fold and 9-fold greater in KB HiFR cells when FT-PL-MLP is compared to non-targeted PL-MLP liposomes. The cytotoxic activity of FT-PL-MLP liposomes was significantly increased up to ~5-fold compared with PL-MLP liposomes in all tested HiFR expressing cell lines. The enhanced uptake and intracytoplasmic liposome delivery was confirmed by confocal fluorescence studies with Rhodamine-labeled liposomes. In vivo, no significant differences in pharmacokinetics and biodistribution were observed when PL-MLP was compared to FT-PL-MLP by the intravenous route. However, when liposomes were directly injected into the peritoneal cavity of mice with malignant ascites of J6456 HiFR lymphoma cells, the tumor cell levels of MLP were significantly greater with the folate-targeted liposomes. Thus, folate targeting enhances liposome uptake by tumor cells enabling intracellular activation of prodrug in the absence of exogenous reducing agents, and leading to increased cytotoxicity. These results may be particularly relevant to the application of folate-targeted PL-MLP in intracavitary or intravesical treatment of cancer.

Pharmacologic Studies of a Prodrug of Mitomycin C in Pegylated Liposomes (Promitil(®)): High Stability in Plasma and Rapid Thiolytic Prodrug Activation in Tissues.

PURPOSE: Pegylated liposomal (PL) mitomycin C lipid-based prodrug (MLP) has recently entered clinical testing. We studied here the preclinical pharmacology of PL-MLP. METHODS: The stability, pharmacokinetics, biodistribution, and other pharmacologic parameters of PL-MLP were examined. Thiolytic cleavage of MLP and release of active mitomycin C (MMC) were studied using dithiothreitol (DTT), and by incubation with tissue homogenates. RESULTS: MLP was incorporated in the bilayer at 10% molar ratio with nearly 100% entrapment efficiency, resulting in a formulation with high plasma stability. In vitro, DTT induced cleavage of MLP with predictable kinetics, generating MMC and enhancing pharmacological activity. A long circulation half-life of MLP (10-15 h) was observed in rodents and minipigs. Free MMC is either extremely low or undetectable in plasma. However, urine from PL-MLP injected rats revealed delayed but significant excretion of MMC indicating in vivo activation of MLP. Studies in mice injected with H3-cholesterol radiolabeled PL-MLP demonstrated relatively greater tissue levels of H3-cholesterol than MLP. MLP levels were highest in tumor and spleen, and very low or undetectable in liver and lung. Rapid cleavage of MLP in various tissues, particularly in liver, was shown in ex-vivo experiments of PL-MLP with tissue homogenates. PL-MLP was less toxic in vivo than equivalent doses of MMC. Therapeutic studies in C26 mouse tumor models demonstrated dose-dependent improved efficacy of PL-MLP over MMC. CONCLUSIONS: Thiolytic activation of PL-MLP occurs in tissues but not in plasma. Liposomal delivery of MLP confers a favorable pharmacological profile and greater therapeutic index than MMC.

Evidence of Nonuniformity in Urothelium Barrier Function between the Upper Urinary Tract and Bladder.

PURPOSE: We compared the relative permeability of upper urinary tract and bladder urothelium to mitomycin C. MATERIALS AND METHODS: Ex vivo porcine bladder, ureters and kidneys were dissected out and filled with 1 mg ml(-1) mitomycin C. At 60 minutes the organs were emptied and excised tissue samples were sectioned parallel to the urothelium. Sectioned tissue was homogenized and extracted mitomycin C was quantified. Transurothelial permeation across the different urothelia was calculated by normalizing the total amount of drug extracted to the surface area of the tissue sample. Average mitomycin C concentrations at different tissue depths (concentration-depth profiles) were calculated by dividing the total amount of drug recovered by the total weight of tissue. RESULTS: Mitomycin C permeation across the ureteral urothelium was significantly greater than across the bladder and renal pelvis urothelium (9.07 vs 0.94 and 3.61 µg cm(-2), respectively). Concentrations of mitomycin C in the ureter and kidney were markedly higher than those achieved in the bladder at all tissue depths. Average urothelial mitomycin C concentrations were greater than 6.5-fold higher in the ureter and renal pelvis than in the bladder. CONCLUSIONS: To our knowledge we report for the first time that the upper urinary tract and bladder show differing permeability to a single drug. Ex vivo porcine ureter is significantly more permeable to mitomycin C than bladder urothelium and consequently higher mitomycin C tissue concentrations can be achieved after topical application. Data in this study correlate with the theory that mammalian upper tract urothelium represents a different cell lineage than that of the bladder and it is innately more permeable to mitomycin C.