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.

Characterization of Contrast Agent Microbubbles for Ultrasound Imaging and Therapy Research

The high efficiency with which gas microbubbles can scatter ultrasound compared with the surrounding blood pool or tissues has led to their widespread employment as contrast agents in ultrasound imaging. In recent years, their applications have been extended to include super-resolution imaging and the stimulation of localized bio-effects for therapy. The growing exploitation of contrast agents in ultrasound and in particular these recent developments have amplified the need to characterize and fully understand microbubble behavior. The aim in doing so is to more fully exploit their utility for both diagnostic imaging and potential future therapeutic applications. This paper presents the key characteristics of microbubbles that determine their efficacy in diagnostic and therapeutic applications and the corresponding techniques for their measurement. In each case, we have presented information regarding the methods available and their respective strengths and limitations, with the aim of presenting information relevant to the selection of appropriate characterization methods. First, we examine methods for determining the physical properties of microbubble suspensions and then techniques for acoustic characterization of both suspensions and single microbubbles. The next section covers characterization of microbubbles as therapeutic agents, including as drug carriers for which detailed understanding of their surface characteristics and drug loading capacity is required. Finally, we discuss the attempts that have been made to allow comparison across the methods employed by various groups to characterize and describe their microbubble suspensions and promote wider discussion and comparison of microbubble behavior.

Functional POR A503V is associated with the risk of bladder cancer in a Chinese population

Human cytochrome P450 oxidoreductase (POR) plays important roles in the metabolism of exogenous carcinogens and endogenous sterol hormones. However, few studies have explored the association between POR variants and the risk of bladder cancer. In this study, we first sequenced all 16 POR exons among 50 randomly selected controls, and found three variants, rs1135612, rs1057868 (A503V) and rs2228104, which were then assessed the relation to risk of bladder cancer in a case-control study of 1,050 bladder cancer cases and 1,404 cancer-free controls in a Chinese population. People with A503V TT genotype have a decreased risk of bladder cancer in a recessive model (TT vs. CC/CT, OR = 0.73, 95% CI = 0.57–0.93), which was more pronounced among elderly male, non-smoking, subjects. Especially, A503V TT genotype showed a protective effect in the invasive tumor stage. Functional analysis revealed that A503V activity decreased in cytochrome c reduction (50.5 units/mg vs. 135.4 units/mg), mitomycin C clearance (38.3% vs. 96.8%), and mitomycin C-induced colony formation (78.0 vs 34.3 colonies per dish). The results suggested that POR A503V might decrease the risk of bladder cancer by reducing its metabolic activity, and should be a potential biomarker for predicting the susceptibility to human bladder cancer.

Serum complement enhances the responses of genotoxin- and oxidative stress-sensitive Escherichia coli bioreporters

Bacterial bioreporters are limited in their abilities to detect large polar molecules due to their membrane selectivity. In this study, the activity of serum complement was used to bypass this undesired selectivity. Initially, the serum complement activity was assessed using the responses of a bacterial bioreporter harboring a recA::luxCDABE transcriptional fusion when exposed to the chemotherapy drug, mitomycin C (MMC). Using 50 °C-treated serum, the limit of detection for this bacterial sensor was lowered by nearly 450-fold, from 31 μg/L to 0.07 μg/L MMC. Real-time quantitative PCR demonstrated that serum-treated cultures responded more strongly to 100 μg/L MMC, with 3.1-fold higher recA expression levels. Subsequent experiments with other bioreporter strains also found enhanced sensitivities and responses. Finally, combining each of the above findings, tests were performed to demonstrate the potential application of the recA::luxCDABE bioreporter within a lab-on-a-CD platform as a point-of-care diagnostic to measure chemotherapeutic drug concentrations within blood.

Anticancer potency of cytotoxic drugs after exposure to high-intensity focused ultrasound in the presence of microbubbles and hematoporphyrin

Chemotherapy is undertaken perioperatively to improve the efficacy of high-intensity focused ultrasound (HIFU) for solid tumors. HIFU at a sufficient intensity for tissue ablation has recently been applied for drug delivery; ultrasonic cavitation plays an important part in HIFU and drug delivery. Hematoporphyrin and microbubbles are adjuncts because they aid cavitation. The effect of HIFU (1.0 MHz; 12,999 W/cm(2) in continuous waves), in the presence of hematoporphyrin and/or microbubbles, on the anticancer potency of 5-fluorouracil, cisplatin, paclitaxel, mitomycin C or adriamycin, was investigated. Insonated adriamycin resulted in a lower death rate of human cancer cells HO-8910 (45.85 ± 2.65% vs 34.84 ± 1.21%, p < 0.05), which was exacerbated when employing hematoporphyrin (34.84 ± 1.21% vs 23.09 ± 7.82%, p < 0.05) or hematoporphyrin combined with microbubbles (34.84 ± 1.21% vs. 8.79 ± 3.69%, p < 0.05); the therapeutic activity was not affected when adding microbubbles alone. High-performance liquid chromatography detected a smaller peak area after subjecting adriamycin to HIFU with the use of hematoporphyrin alone or combined with microbubbles. The other drugs were not affected. Hematoporphyrin, microbubbles and adriamycin increased the throughput of hydroxyl radicals resulting from cavitation as determined by iodine and methylene blue assays. These data suggested that the anticancer activity of a drug may be decreased by HIFU exposure (particularly in the presence of hematoporphyrin and microbubbles). Cavitation produced reactive species that attacked drug molecules, thereby decreasing their antitumor potency; this process was enhanced if the drug itself generated free radicals under insonation.

The role of a combined regimen with intravesical chemotherapy and hyperthermia in the management of non-muscle-invasive bladder cancer: a systematic review

CONTEXT

Due to the suboptimal clinical outcomes of current therapies for non-muscle-invasive bladder cancer (NMIBC), the search for better therapeutic options continues. One option is chemohyperthermia (C-HT): microwave-induced hyperthermia (HT) with intravesical chemotherapy, typically mitomycin C (MMC). During the last 15 yr, the combined regimen has been tested in different clinical settings.

OBJECTIVE

To perform a systematic review to evaluate the efficacy of C-HT as a treatment for NMIBC.

EVIDENCE ACQUISITION

The review process followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. An electronic search of the Medline, Embase, Cochrane Library, CancerLit, and ClinicalTrials.gov databases was undertaken. Relevant conference abstracts and urology journals were also searched manually. Two reviewers independently reviewed candidate studies for eligibility and abstracted data from studies that met inclusion criteria. The primary end point was time to recurrence. Secondary end points included time to progression, bladder preservation rate, and adverse event (AE) rate.

EVIDENCE SYNTHESIS

A total of 22 studies met inclusion criteria and underwent data extraction. When possible, data were combined using random effects meta-analytic techniques. Recurrence was seen 59% less after C-HT than after MMC alone. Due to short follow-up, no conclusions can be drawn about time to recurrence and progression. The overall bladder preservation rate after C-HT was 87.6%. This rate appeared higher than after MMC alone, but valid comparison studies were lacking. AEs were higher with C-HT than with MMC alone, but this difference was not statistically significant.

CONCLUSIONS

Published data suggest a 59% relative reduction in NMIBC recurrence when C-HT is compared with MMC alone. C-HT also appears to improve bladder preservation rate. However, due to a limited number of randomized trials and to heterogeneity in study design, definitive conclusions cannot be drawn. In the future, C-HT may become standard therapy for high-risk patients with recurrent tumors, for patients who are unsuitable for radical cystectomy, and in cases for which bacillus Calmette-Guérin treatment is contraindicated.

Validation and use of microdialysis for determination of pharmacokinetic properties of the chemotherapeutic agent mitomycin C - an experimental study

BACKGROUND

Mitomycin C is a chemotherapeutic agent used in the treatment of peritoneal surface malignancies, administered as hyperthermic intraperitoneal chemotherapy after cytoreductive surgery. Pharmacokinetic studies have been based on analyses of blood, urine and abdominal perfusate, but actual tissue concentrations of the drug have never been determined. Microdialysis is an established method for continuous monitoring of low-molecular substances in tissues, and in the present study microdialysis of mitomycin C was studied in vitro and in vivo.

METHODS

Using in vitro microdialysis, relative recovery was determined when varying drug concentration, temperature and perfusion flow rate. In vivo microdialysis was performed in rats to verify long-term stability of relative recovery in four compartments (vein, peritoneum, extraperitoneal space and hind leg muscle). Subsequently, intravenous and intraperitoneal bolus infusion experiments were performed and pharmacokinetic parameters were calculated.

RESULTS

In vitro, compatibility of mitomycin C and microdialysis equipment was demonstrated, and relative recovery was stable over an adequate concentration range, moderately increased by raising medium temperature and increased when flow rate was reduced, all according to theory. In vivo, stable relative recovery was observed over seven hours. Mitomycin C exhibited fast and even distribution in rat tissues, and equal bioavailability was achieved by intravenous and intraperitoneal infusion. The half-life of mitomycin C calculated after intravenous infusion was 40 minutes.

CONCLUSIONS

Mitomycin C concentration can be reliable monitored in vivo using microdialysis, suggesting that this technique can be used in pharmacokinetic studies of this drug during hyperthermic intraperitoneal chemotherapy.

Pharmacokinetics of mitomycin C after resection of peritoneal carcinomatosis and intraperitoneal chemohyperthermic perfusion

Over the last few years surgery on patients with abdominal malignancies has become more aggressive but the majority of patients present locoregional recurrence as peritoneal dissemination. Cytoreductive surgery followed by intraperitoneal chemohyperthermic perfusion (ICHP) has been described for treatment and prevention of locoregional cancer spread from various origins. This paper reports our study of the pharmacokinetics of mitomycin C (MMC) administered by intraperitoneal chemohyperthermic perfusion (ICHP) in patients with peritoneal carcinomatosis. 28 patients received MMC 20 mg/m2 intraperitoneally as a perfusion over 60 min. MMC was determined in perfusate, plasma and urine samples with a UV-HPLC method. A compartmental model was used to fit the drug concentrations in plasma and perfusate. Our results showed a mean maximum plasma concentration (Cmax) of 0.14 +/- 0.086 microg/ml with a peak time (Tmax) of 48..7 +/- 5.61 min. The mean area under the curve (AUC) and terminal half-life (t1/2) were 15.8 +/- 9.8 mg x min/L and 83.7 +/- 31.74 min respectively. Clearance (CL) was estimated by fitting the data by a compartmental model and the mean value was 72 +/- 66 L/h. The percent of the dose absorbed was very variable and ranged between 14 and 57% (mean 37 +/- 14%). The mean percentage of dose recovered unchanged in the urine during 24 hours was 7.21 +/- 3.73%. We conclude that ICHP in patients with peritoneal surface malignancies seems to have clinical value since it gives high peritoneal and tumor MMC concentrations with limited systemic exposure and toxicity.

LC-ESI-MSD fast determination of residual mitomycin C in hen aqueous humour after corneal refractive surgery

A simple, fast and reliable method has been developed for the assay of traces of mitomycin C (MMC) in hen aqueous humour samples. The determination was carried out by high-performance liquid chromatography with electrospray ionization mass spectrometric detection. In isocratic elution analysis, the mobile phase was a mixture of water-acetonitrile (78:22, v/v) and the chromatographic column was C(18) at 35 degrees C. The method has been validated over a range from 0.1 to 250 microg L(-1) in hen aqueous humour with correlation coefficients higher than 0.999. Limit of detection and limit of quantification for MMC based in signal to noise ratio of 3 and 10, respectively, were 20 and 71 ng L(-1). The developed method allows the analysis of MMC in hen aqueous humour samples obtained at different times and conditions in order to evaluate and compare the efficacy of the drug administration.

Combination of intravesical chemotherapy and hyperthermia for the treatment of superficial bladder cancer: preliminary clinical experience

The prevalence of superficial transitional cell carcinoma of the bladder (STCCB) is still increasing in spite of improved adjuvant chemotherapeutic and/or immunoprophylaxis approaches. Thus, there is certainly an urgent need to improve our ability to control this disease. Local hyperthermia has a therapeutical potential for the treatment of many solid tumors, especially when used in combination with other treatments, such as radiation and chemotherapy. In particular, a synergistic or, at least, supra-additive anti-tumor cell killing effect was documented when local hyperthermia was administered in combination with selected cytostatic drugs. Recently, advances in miniaturized technology have allowed the development of a system specifically designed for delivering an endovesical thermo-chemotherapy regimen in humans. In preliminary clinical experiences, insofar mainly carried out as mono-institutional investigations, the combined treatment using this system was demonstrated to be feasible, minimally invasive and safe when performed on out-patient basis. Moreover, the anti-tumoral efficacy seemed to be significantly enhanced when compared with that obtained using intravesical chemotherapy alone for both adjuvant (prophylaxis) and neo-adjuvant (ablative) approaches to superficial bladder cancer.

Pharmacokinetics of intraarterial mitomycin C in hypoxic hepatic infusion with embolization in the treatment of liver metastases

1. The pharmacokinetics of mitomycin C (MMC) was evaluated during hypoxic hepatic infusion (HHMI) with arterial embolization for the treatment of unresectable liver metastases. 2. Ten patients with hepatic metastases from colorectal cancer were considered. Antiblastic infusion with MMC (20 mg/m2 at 30 ml/min) was initiated after 10 min of hepatic arterial occlusion. Peripheral venous blood samples were collected at different time intervals. MMC was assayed by high-pressure liquid chromatography (HPLC), and pharmacokinetic parameters were determined using an open, two-compartment model and linear kinetics. 3. Cmax of MMC during HHMI was 708 +/- 336.6 ng/ml, and tmax was 9.3 +/- 1.1 min. The plasma concentration-time curve showed a t1/2 alpha ranging from 1.5 to 9 min, followed by a t1/2 beta ranging from 31 to 93 min. The Cltot was 35.5 l/h/m2 with an area under the plasma concentration-time curve (AUC) ranging from 251 to 850 micrograms h/l. The same AUC parameter standardized for the amount of MMC was 15.5 mg-1. The HHMI model that we used revealed a significant increase in Cltot and a reduction in AUC when compared to the locoregional intraarterial and peripheral intravenous models (p < .001). 4. The reduction in AUC following HHMI explains the limited systemic toxicity in treated patients, with a greater total tumor exposure to the drug and improved drug activation.

Effect of local hyperthermia of the bladder on mitomycin C pharmacokinetics during intravesical chemotherapy for the treatment of superficial transitional cell carcinoma

AIMS

To assess the effect of local hyperthermia on the systemic absorption of mitomycin C (MMC) during intravesical chemotherapy for the treatment of superficial transitional cell carcinoma of the bladder, and to establish the likely safety of this procedure.

METHODS

Group 1 (n = 12) received 20 mg intravesical MMC plus local hyperthermia, group 2 (n = 13) 20 mg MMC alone, group 3 (n = 16) 40 mg MMC plus local hyperthermia and group 4 (n = 10) 40 mg MMC alone. Patients in groups 1, 2, and 4 underwent post-tumour resection adjuvant treatment, whereas those in group 3 still had tumour present and were treated to eradicate it. Intravesical instillation lasted 60 min, with the solution (50 ml) being replaced after the first 30 min. Blood samples were taken before, and every 15 min during instillation. MMC concentrations in plasma and in urine were determined by h.p.l.c.

RESULTS

The highest MMC plasma concentration (67.9 ng ml(-1)) occurred in a patient in group 3. This value was well below the threshold concentration (400 ng ml-1) for myelosuppression. Local hyperthermia associated with the intravesical chemotherapy enhanced plasma MMC concentrations at 30, 45 and 60 min compared with chemotherapy alone (Group 1 vs 2, P < or = 0.008). Systemic exposure to MMC was not significantly increased by doubling the intravesical dose when intravesical chemotherapy alone was administered. Patients in group 3 displayed the highest degree of MMC absorption and the greatest variability in pharmacokinetics between patients.

CONCLUSIONS

Local hyperthermia enhances the systemic absorption of MMC during intravesical chemotherapy for bladder cancer. In the doses used, plasma MMC concentrations were always more than six times lower than those shown to cause toxicity.

Quantitation of mitomycin C in human ocular tissues by high-performance liquid chromatography-photo-diode array detection

A chromatographic method, which can quantitate mitomycin C (MMC) along with two antiglaucoma drugs, is described. The separation of MMC, alphagan and timolol was performed on a reversed-phase C18 column with water-methanol-trifluoroacetic acid (65:35:0.01, v/v) as the mobile phase. By monitoring at 360, 248 and 296 nm, the lower limits of detection for MMC, alphagan and timolol are, respectively, 1.0, 2.0 and 5.0 ng (injection amount) at three-time S/N ratio. The dynamic ranges of quantitation for the three drugs are, respectively, 1.0 ng-10.0 microg, 2.0 ng-10.0 microg and 5.0 ng-10.0 microg with linearity being larger than 0.9960. This method was applied to the determination of MMC levels in Tenon's and trabeculum tissues of 10 glaucoma patients. MMC levels in these tissues, which were obtained from glaucoma filtering surgery, were determined following a multiple extraction with methanol. The recovery of MMC for a two-batch extraction was better than 91.2%. The reproducibility of measurement for the MMC levels in these tissues is 2.5-6.0% RSD for triplicate injections. The intra-day variation of retention times for the MMC peaks was less than 1.6% RSD (n=3). The inter-day variation of retention times for the MMC peaks was less than 4.8% RSD (n=3). MMC was detectable in three trabeculum tissues out of 10 cases (ranging from 0.8 to 25.5 ng/mg specimen), while MMC was detected in nine Tenon's tissues out of 10 cases (ranging from 0.3 to 21.1 ng/mg specimen). The results obtained show that the method is sensitive and selective for the quantitation of MMC.