Cysteine specific targeting of the functionally distinct peroxiredoxin and glutaredoxin proteins by the investigational disulfide BNP7787.

Glutaredoxin (Grx), peroxiredoxin (Prx), and thioredoxin (Trx) are redoxin family proteins that catalyze different types of chemical reactions that impact cell growth and survival through functionally distinct intracellular pathways. Much research is focused on understanding the roles of these redoxin proteins in the development and/or progression of human diseases. Grx and Prx are overexpressed in human cancers, including human lung cancers. BNP7787 is a novel investigational agent that has been evaluated in previous clinical studies, including non-small cell lung cancer (NSCLC) studies. Herein, data from activity assays, mass spectrometry analyses, and X-ray crystallographic studies indicate that BNP7787 forms mixed disulfides with select cysteine residues on Grx and Prx and modulates their function. Studies of interactions between BNP7787 and Trx have been conducted and reported separately. Despite the fact that Trx, Grx, and Prx are functionally distinct proteins that impact oxidative stress, cell proliferation and disease processes through different intracellular pathways, BNP7787 can modify each protein and appears to modulate function through mechanisms that are unique to each target protein. Tumor cells are often genomically heterogeneous containing subpopulations of cancer cells that often express different tumor-promoting proteins or that have multiple dysregulated signaling pathways modulating cell proliferation and drug resistance. A multi-targeted agent that simultaneously modulates activity of proteins important in mediating cell proliferation by functionally distinct intracellular pathways could have many potentially useful therapeutic applications.

Enzymatic and non-enzymatic mechanisms of dimesna metabolism.

The chemical reduction of the disulfide homodimer dimesna to its constituent mesna moieties is essential for its mitigation of nephrotoxicity associated with cisplatin and ifosfamide anticancer therapies and enhancement of dialytic clearance of the cardiovascular risk factor homocysteine. The objective of this study was to investigate potential enzymatic and non-enzymatic mechanisms of intracellular dimesna reduction. Similar to endogenous intracellular disulfides, dimesna undergoes thiol-disulfide exchange with thiolate anion-forming sulfhydryl groups via the two-step SN2 reaction. Determination of equilibrium constants of dimesna reduction when mixed with cysteine or glutathione provided a mechanistic explanation for dramatic cysteine and homocysteine depletion, but sparing of the endogenous antioxidant glutathione, previously observed during mesna therapy. Dimesna was reduced by recombinant enzymes of the thioredoxin system; however, oxidation of NADPH by the glutaredoxin system was only observed in the presence of combined dimesna and reduced glutathione, suggesting formation of oxidized glutathione following an initial non-enzymatic reduction of dimesna. Production of mesna by enzymatic and non-enzymatic mechanisms in HeLa cell lysate following dimesna incubation was demonstrated by a loss in mesna production following protein denaturation and prediction of residual non-enzymatic mesna production by mathematical modeling of thiol-disulfide exchange reactions. Reaction modeling also revealed that mixed disulfides make up a significant proportion of intracellular thiols, supporting their role in providing additional nephroprotection, independent of direct platinum conjugation.

In vitro and in vivo assessment of renal drug transporters in the disposition of mesna and dimesna.

Mesna and its dimer, dimesna, are coadministered for mitigation of ifosfamide- and cisplatin-induced toxicities, respectively. Dimesna is selectively reduced to mesna in the kidney, producing its protective effects. In vitro screens of uptake and efflux transporters revealed saturable uptake by renal organic anion transporters OAT1, OAT3, and OAT4. Efflux transporters breast cancer resistance protein; multidrug and toxin extrusion 1 (MATE1); multidrug resistance proteins MRP1, MRP2, MRP4, and MRP5; and P-glycoprotein (Pgp) significantly reduced dimesna accumulation. Further investigation demonstrated that renal apical efflux transporters MATE1, MRP2, and Pgp were also capable of mesna efflux. Administration of OAT inhibitor probenecid to healthy subjects significantly increased combined mesna and dimesna plasma exposure (91% ± 34%) while decreasing the renal clearance due to net secretion (67.0% ± 12.7%) and steady-state volume of distribution (45.2% ± 13.4%). Thus, the kidney represents a significant sink of total mesna, whereas function of renal drug transporters facilitates clearance in excess of glomerular filtration rate and likely the presence of active mesna in the urine. Loss of renal transporter function due to genetic variability or drug-drug interactions may decrease the efficacy of chemoprotectants, increasing the risk of ifosfamide- and cisplatin-induced toxicities.

Accumulation of BNP7787 in human renal proximal tubule cells.

BNP7787, an investigational drug undergoing global Phase III development, appears to have potential advantages over other cytoprotective compounds that have been evaluated for preventing and mitigating cisplatin-induced nephrotoxicity. Herein, we characterized the in vitro accumulation of BNP7787 in human renal proximal tubule cells (HK-2) in which cisplatin is known to be taken up and accumulate. HK-2 cells were incubated with pharmacological concentrations of BNP7787 for varying times. Temperature-dependent accumulation of BNP7787 in cells was observed and the BNP7787-derived metabolite, mesna, formed intracellularly was directly monitored. The peak level of BNP7787-derived mesna measured in HK-2 cells was approximately 0.6 nmol/10(6) cells; this is pharmacologically similar to reported platinum concentrations in kidney cells and may be sufficient to afford nephroprotection. Therefore, in addition to previously suggested glomerular filtration, the cellular accumulation of BNP7787 by HK-2 cells is a plausible newly identified mechanism by which BNP7787 may accumulate in renal tubular cells, where it can exert its pharmacological effects to protect against cisplatin-induced nephrotoxicity by direct covalent conjugation of mesna with cisplatin, or by the formation of BNP7787-derived mesna-disulfide heteroconjugates that exert nephroprotective effects by inhibition of the key toxification enzyme targets γ-glutamyltranspeptidase and aminopeptidase N.

Phase I and pharmacologic study of BNP7787, a novel chemoprotector in patients with advanced non-small cell lung cancer.

PURPOSE: We conducted a phase I trial of BNP7787 (disodium 2,2'-dithio-bis-ethane sulfonate, Tavocept™), a novel chemoprotective and antitumor enhancing agent administered in combination with paclitaxel and cisplatin. The primary aim was to determine a safe and potentially efficacious BNP7787 dose for preventing and mitigating paclitaxel- and cisplatin-induced toxicities and to evaluate for preliminary evidence of efficacy of treatment. PATIENTS AND METHODS: Twenty-two patients with stage IIIB/IV non-small cell lung cancer (NSCLC) received BNP7787 alone 1 week before co-administration of BNP7787 with paclitaxel followed by cisplatin. Twenty-one patients were treated with BNP7787 in escalating doses of 4.1-41.0 g/m² concurrently with paclitaxel 175 mg/m² and cisplatin 75 mg/m² every 3 weeks. RESULTS: The appropriate dose was determined to be 18.4 g/m² of BNP7787 although no dose-limiting toxicity was observed up to 41.0 g/m². Mild intravenous site discomfort, thirst, and nausea were the most common toxicities. One patient developed grade 2 skin rash, which was severe enough to preclude further study treatment. The AUC(0-inf) of the metabolite mesna was approximately 6.3% of the AUC(0-inf) of BNP7787. Co-administration of paclitaxel and cisplatin did not appear to influence the pharmacokinetics of BNP7787 and mesna. The overall response rate was encouraging; 43% including 11 patients with prior chemotherapy. CONCLUSIONS: The recommended dose for phase II/III studies is 18.4 mg/m² of BNP7787 in combination with paclitaxel and cisplatin. Further studies are warranted to assess whether BNP7787 prevents and mitigates common and serious paclitaxel- and cisplatin-related side effects and enhances the efficacy of paclitaxel and cisplatin in advanced NSCLC patients.

Mesna for treatment of hyperhomocysteinemia in hemodialysis patients: a placebo-controlled, double-blind, randomized trial.

BACKGROUND AND OBJECTIVES: Increased plasma total homocysteine is a graded, independent risk factor for the development of atherosclerosis and thrombosis. More than 90% of patients with end-stage renal disease have hyperhomocysteinemia despite vitamin supplementation. It was shown in previous studies that a single intravenous dose of mesna 5 mg/kg caused a drop in plasma total homocysteine that was significantly lower than predialysis levels 2 d after dosing. It was hypothesized 5 mg/kg intravenous mesna administered thrice weekly, before dialysis, for 8 wk would cause a significant decrease in plasma total homocysteine compared with placebo. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Patients with end-stage renal disease were randomly assigned to receive either intravenous mesna 5 mg/kg or placebo thrice weekly before dialysis. Predialysis plasma total homocysteine concentrations at weeks 4 and 8 were compared between groups by paired t test. RESULTS: Mean total homocysteine at 8 wk in the placebo group was 24.9 micromol/L compared with 24.3 micromol/L in the mesna group (n = 22 [11 pairs]; mean difference 0.63). Interim analysis at 4 wk also showed no significant difference between mesna and placebo (n = 32 [16 pairs]; placebo 26.3 micromol/L, mesna 24.5 micromol/L; mean difference 1.88). Multivariable adjustments for baseline characteristics did not alter the analysis. Plasma mesna seemed to reach steady-state concentrations by 4 wk. CONCLUSIONS: It is concluded that 5 mg/kg mesna does not lower plasma total homocysteine in hemodialysis patients and that larger dosages may be required.

Mesna as a nonvitamin intervention to lower plasma total homocysteine concentration: implications for assessment of the homocysteine theory of atherosclerosis.

Elevated plasma total homocysteine is independently associated with atherosclerosis. Recent randomized trials show that vitamins lower total homocysteine but do not prevent cardiovascular events, suggesting the need for nonvitamin therapies to evaluate whether a causative relationship exists. Mesna (sodium 2-mercaptoethanesulfonate) is a thiol-containing drug capable of liberating homocysteine bound by disulfide bonds to proteins, facilitating its excretion. The effect of oral mesna on total homocysteine has not been evaluated and was the objective of this study. Eleven healthy volunteers received vehicle or 10 mg/kg mesna in random order, after which serial blood and urine samples were collected over 4 hours. Plasma total homocysteine decreased by 24.2% (P < .0001) following mesna. Urinary homocysteine excretion was significantly greater with mesna (3.9 +/- 2.4 mumol) compared to vehicle (0.4 +/- 0.1 mumol), P < .01. Oral mesna decreases plasma total homocysteine and is a potential nonvitamin treatment for assessing the homocysteine theory of atherosclerosis.

Phase I and pharmacokinetic study of the novel chemoprotector BNP7787 in combination with cisplatin and attempt to eliminate the hydration schedule.

BNP7787 (disodium 2,2'-dithio-bis-ethane sulphonate; Tavocept) is a novel agent developed to protect against cisplatin (cis-diammine-dichloroplatinum(II))-associated chronic toxicities. In this study, we determined the recommended dose of BNP7787 when preceding a fixed dose of cisplatin, the pharmacokinetics (PKs) and the possible reduction of saline hydration. Patients with advanced solid tumours received BNP7787 in escalating doses of 4.1-41 g m(-2) as a 15-min intravenous (i.v.) infusion followed by cisplatin 75 mg m(-2) as a 60-min i.v. infusion together with pre- and postcisplatin saline hydration in a volume of 2200 ml; cycles were repeated every 3 weeks. PK was carried out using BNP7787, cisplatin and the combination. Twenty-five patients were enrolled in stage I of the study to determine the recommended dose of BNP7787. No dose-limiting toxicity was reached. The highest dose level of 41 g m(-2) resulted in a low incidence of grade 2 toxicities, being nausea and vomiting, dry mouth or bad taste and i.v. injection site discomfort. Doses of BNP7787 > or = 18.4 g m(-2) did not show a drug interaction between BNP7787 and cisplatin. In stage II of the study, patients received a fixed dose of BNP7787 of 18.4 g m(-2) preceding cisplatin and were entered in prespecified reduced saline hydration steps. A total of 21 patients in cohorts of six to nine patients received reduced saline hydration of 1600 ml (step A), 1000 ml (step B) and 500 ml (step C). In step C, two out of six evaluable patients experienced grade 1 nephrotoxicity. Cisplatin acute toxicities in all 46 patients were as expected. Only five patients complained of paresthesias grade 1 and six developed slight audiometric changes. Partial tumour response was observed in four patients and stable disease in 15 patients. In conclusion, BNP7787 was tolerated well up to doses of 41 g m(-2). The recommended dose of 18.4 g m(-2) enabled safe reduction of the saline hydration schedule for cisplatin to 1000 ml. Further studies will assess whether BNP7787 offers protection against platinum-related late side effects.

Attenuation of bleomycin-induced lung fibrosis in rats by mesna.

Lung fibrosis is a common side effect of the chemotherapeutic agent, bleomycin. Current evidence suggests that reactive oxygen species may play a key role in the development of lung fibrosis. The present study examined the effect of mesna on bleomycin-induced lung fibrosis in rats. Animals were divided into three groups: (1) saline control group; (2) Bleomycin group in which rats were injected with bleomycin (15 mg/kg, i.p.) three times a week for four weeks; (3) Bleomycin and mesna group, in which mesna was given to rats (180 mg/kg/day, i.p.) a week prior to bleomycin and daily during bleomycin injections for 4 weeks until the end of the treatment. Bleomycin treatment resulted in a pronounced fall in the average body weight of animals. Bleomycin-induced pulmonary injury and lung fibrosis was indicated by increased lung hydroxyproline content, and elevated nitric oxide synthase, myeoloperoxidase, platelet activating factor, and tumor necrosis factor-alpha in lung tissues. On the other hand, bleomycin induced a reduction in reduced glutathione concentration and angiotensin converting enzyme activity in lung tissues. Moreover, bleomycin-induced severe histological changes in lung tissues revealed as lymphocytes and neutrophils infiltration, increased collagen deposition and fibrosis. Co-administration of bleomycin and mesna reduced bleomycin-induced weight loss and attenuated lung injury as evaluated by the significant reduction in hydroxyproline content, nitric oxide synthase activity, and concentrations of myeoloperoxidase, platelet activating factor, and tumor necrosis factor-alpha in lung tissues. Furthermore, mesna ameliorated bleomycin-induced reduction in reduced glutathione concentration and angiotensin activity in lung tissues. Finally, histological evidence supported the ability of mesna to attenuate bleomycin-induced lung fibrosis and consolidation. Thus, the findings of the present study provide evidence that mesna may serve as a novel target for potential therapeutic treatment of lung fibrosis.

Possible (enzymatic) routes and biological sites for metabolic reduction of BNP7787, a new protector against cisplatin-induced side-effects.

Disodium 2,2'-dithio-bis-ethane sulfonate (BNP7787) is under investigation as a potential new chemoprotector against cisplatin-induced nephrotoxicity. The selective protection of BNP7787 appears to arise from the preferential uptake of the drug in the kidneys, where BNP7787 would undergo intracellular conversion into mesna (2-mercapto ethane sulfonate), which in turn can prevent cisplatin induced toxicities. In the present study, we have investigated whether the reduction of BNP7787 into the reactive compound mesna is restricted to the kidney or whether it can also occur in other organs, cells and physiological compartments, including the cytosolic fraction of the renal cortex, plasma, red blood cells (RBCs), liver and small intestine from rats and several tumors (OVCAR-3, MRI-H-207 and WARD). We also determined whether the endogenous thiols glutathione (GSH) and cysteine and the enzyme systems glutaredoxin and thioredoxin, which are all present in the kidney, can be involved in the BNP7787 reduction. UV detection and micro-HPLC with dual electrochemical detection were used to analyze the various incubation mixtures. Our observations are that, in contrast to plasma, a very large reductive conversion of BNP7787 to mesna was measured in RBC lysate. Intact RBCs, however, did not take up BNP7787. Although BNP7787 could be reduced in cytosol of liver and several tumors, this reduction will not be relevant in vivo, since these tissues do not take up large amounts of BNP7787. Kidney cortex cytosol was, similar to the small intestine cytosol, able to substantially reduce BNP7787 to mesna. The ability to reduce BNP7787 in the presence of the endogenous thiols GSH and cysteine, the glutaredoxin system as well as the thioredoxin system, could at least in part explain the high BNP7787 reductive activity of the kidney cortex cytosol. In conclusion, the high reduction of BNP7787 into mesna in the kidney as well as our earlier observation that the distribution of BNP7787 and mesna was mainly restricted to rat kidney are strong arguments in favor of selective protection of the kidney by BNP7787.

Pharmacokinetic behaviour of the chemoprotectants BNP7787 and mesna after an i.v. bolus injection in rats.

In preclinical studies, BNP7787 (disodium 2,2'-dithio-bis-ethane sulphonate), the disulphide form of mesna, has demonstrated selective protection against cisplatin-induced nephrotoxicity due to conversion into mesna inactivating toxic platinum species. Mesna (sodium 2-mercapto ethane sulphonate), however, can affect the antitumour activity of cisplatin, while BNP7787 does not interfere with the antitumour activity. To understand the difference in interference with cisplatin-induced antitumour activity between BNP7787 and mesna as well to characterise the selective nephroprotection by BNP7787, the pharmacokinetics of BNP7787 and mesna, each given i.v. 1000 mg x kg(-1), were determined in plasma, kidney, liver, red blood cells (RBC), skeletal muscle and tumour of Fischer rats bearing subcutaneously implanted WARD colon tumours. The following results were obtained: (1). high concentrations of BNP7787 and mesna were observed in the plasma and kidney after administration of BNP7787 or mesna, except for mesna in plasma after BNP7787 administration; (2). in all other sampled compartments, the AUC values of both compounds were at least 5.5-fold lower than the corresponding values in kidney; (3). the AUC of mesna in plasma after mesna administration was comparable to the AUC of mesna in kidney after a dose of BNP7787 that can completely prevent cisplatin-induced nephrotoxicity in rats; (4). the AUC of mesna in plasma was five-fold higher relative to the AUC of mesna following BNP7787 administration (P<0.01). In conclusion, the five-fold higher AUC of mesna in plasma after mesna administration and the fact that mesna is more reactive with (hydrated) cisplatin than its disulphide form BNP7787 represent a plausible explanation as to why mesna administration can reduce the antitumour activity of cisplatin. After BNP7787 administration, the distribution of BNP7787 and mesna was restricted to the kidney, which confirmed the selective protection of the kidney by BNP7787.

BNP-7787 (BioNumerik/Baxter Oncology/Grelan).

BioNumerik Pharmacology Inc, Baxter Oncology GmbH (formerly ASTA Medica AG) and Grelan Pharmaceutical Co Ltd are developing BNP-7787 for the potential reduction of toxicity associated with cisplatin and carboplatin treatment in cancer patients.

Crossover randomized comparison of intravenous versus intravenous/oral mesna in soft tissue sarcoma treated with high-dose ifosfamide.

PURPOSE: We conducted our study to determine the pharmacokinetics (PK) and clinical efficacy of oral mesna in patients receiving ifosfamide for soft tissue sarcoma. EXPERIMENTAL DESIGN: Seventeen patients were enrolled in a randomized prospective Phase I/II study. Seventeen patients were exposed to study medication. Ifosfamide was given at a dose of 2 g/m2/day for 5 days on a 21-day cycle. Before the first cycle, all patients were randomized onto a crossover design and received either the approved i.v. or i.v./oral mesna regimen, with crossover for the second cycle of chemotherapy. The i.v. mesna regimen consisted of dosings (20% ifosfamide dose) at 0, 4, and 8 h. The i.v./oral arm consisted of an i.v. mesna dosing (20% ifosfamide dose) at 0 h, followed by oral tablet dosing (40% ifosfamide dose) at 2 and 6 h. In-patient clinical monitoring and phlebotomy and urine sampling for mesna, dimesna, and ifosfamide PK were performed on all chemotherapy days. RESULTS: Thirteen patients were evaluable for PK and 17 for efficacy and toxicity. No significant differences were detected in the plasma PK of the concomitantly infused ifosfamide. Rates of hemorrhagic cystitis were similar across mesna schedules. Four of 10 evaluable patients demonstrated objective response. CONCLUSION: On the basis of our study, an i.v./oral mesna regimen is at least as uroprotective as the approved i.v. regimen. The i.v./oral regimen will improve patient tolerance and convenience, allow for a reduction in elective hospitalizations for ifosfamide chemotherapy, reduce the potential morbidity associated with inpatient administration of chemotherapy, and likely result in decreased costs of care.

Pharmacokinetics and pharmacodynamics of mesna-mediated plasma cysteine depletion.

Cellular glutathione (GSH) levels are related to the resistance of tumor cells to platinum and alkylating agents, and depletion of GSH may enhance the activity of these drugs. The pharmacodynamic effects of mesna on depleting plasma cysteine, a GSH precursor, were evaluated in 22 patients as part of a Phase I study. Escalating doses of ifosfamide and mesna were administered; carboplatin was administered to achieve an AUC of 4 mg x min/mL. Plasma samples were collected and assayed by reverse-phase high-performance liquid chromatography (HPLC) for total mesna and total cysteine concentrations at 0, 1, 3, 6, 24, 25, 28, and 48 hours. A one-compartment pharmacokinetic model was fit to the mesna plasma concentrations, using M.A.P. Bayesian estimation (ADAPT II). Pharmacodynamics were evaluated by fitting an inhibitory Emax model to the cysteine concentration data. Both the pharmacokinetic (median R2 = 0.95; range = 0.85-0.98) and pharmacodynamic (median R2 = 0.96; range = 0.74-1.0) models fit the data well. Mean (coefficient of variation [CV%]) mesna pharmacokinetic parameter estimates were as follows: Vss of 15.3 (29) L/m2, CL of 4.6 (29) L/h/m2, and half-life of 2.2 (37) hours. Mean (CV%) pharmacodynamic parameter estimates were as follows: Emax of 31.7 (19) microg/mL and EC50 of 10.3 (52) microg/mL. Mesna produced a rapid, concentration-dependent reduction in plasma cysteine concentrations that could be adequately characterized by an inhibitory Emax pharmacodynamic model. The depletion of plasma cysteine was facilitated by ifosfamide, suggesting a pharmacodynamic interaction between these two agents. Further increases in mesna doses beyond those administered in this study would be unlikely to provide additional benefit.

Pharmacokinetics and preliminary clinical data of the novel chemoprotectant BNP7787 and cisplatin and their metabolites.

INTRODUCTION: BNP7787 (disodium 2,2'-dithio-bis-ethane sulfonate) is currently undergoing development as a chemoprotective agent to prevent common and serious cisplatin-induced side effects. In the kidneys, intestine, and liver, BNP7787 is believed to undergo intracellular conversion into 2-mercaptoethane sulfonate (mesna), which can locally inactivate toxic platinum species. Methods and objectives In a phase I trial, 25 patients with advanced solid tumors received a 1-hour intravenous infusion of 75 mg/m(2) cisplatin immediately preceded by a 15-minute intravenous infusion of BNP7787 every 3 weeks. For pharmacokinetic investigation of BNP7787 and mesna and a possible mutual pharmacokinetic interaction between BNP7787 and cisplatin, cisplatin and BNP7787 were also administered as single agents in 14 of 25 patients. The dose of BNP7787 was escalated from 4.1 to 41 g/m(2). Patients were also monitored for tumor response and possible side effects from BNP7787. RESULTS: The maximum plasma concentration of mesna was reached approximately 1.7 hours after the start of the BNP7787 infusion. The maximum plasma concentration and area under the curve to infinity (AUC( infinity )) of BNP7787 and mesna increased linearly with the dose. The mean volume of distribution of BNP7787 (+/-SD) was approximately 0.26 +/- 0.08 L/kg. The mean normalized AUC( infinity ) of mesna was only approximately 8% of the normalized AUC( infinity ) of BNP7787. The pharmacokinetic profile of mesna was unaffected by cisplatin and its metabolites. None of the dose levels of BNP7787 (4.1-41 g/m(2)) administered appeared to influence the pharmacokinetic profile of total platinum, unbound platinum, or monohydrated cisplatin. The observed effects regarding a possible mutual interaction between BNP7787 and intact cisplatin were minor, and none were statistically significant at BNP7787 dose levels of 18.4 to 41 g/m(2). The confidence intervals for the pharmacokinetic parameters of BNP7787 and intact cisplatin, however, were relatively broad. Overall, BNP7787 was well tolerated at all dose levels (4.1-41.0 g/m(2)). The most frequently reported event related to BNP7787 was local intravenous site discomfort; the majority of events were mild (grade 1). Side effects of BNP7787 at the highest dose level of 41 g/m(2) were more prominent and included nausea and vomiting, as well as a warm feeling or flushing (grade 2 or lower). Partial tumor responses and stable disease were measured in 12 of 25 patients. CONCLUSION: BNP7787 was relatively nontoxic at doses up to 41 g/m(2). The combination of BNP7787 with cisplatin did not alter the pharmacokinetic profiles of mesna or the cisplatin metabolites. At the higher dose levels of BNP7787 (18.4 to 41 g/m(2)), there appeared to be no mutual interaction between BNP7787 and intact cisplatin, which needs to be confirmed in a larger number of patients. The absence of a mutual interaction between BNP7787 and intact cisplatin is consistent with the observation that several patients had objective tumor responses with BNP7787 and cisplatin administration.

Pharmacokinetics of BNP7787 and its metabolite mesna in plasma and ascites: a case report.

PURPOSE: BNP7787 (2',2'-dithio-bis-ethane sulfonate sodium) is a novel protector against cisplatin-induced toxicities. The pharmacokinetics of BNP7787 and its metabolite mesna were investigated in plasma and ascites of a cancer patient. We also evaluated potential pharmacokinetic interactions between BNP7787 and cisplatin. METHODS: BNP7787 and mesna were measured as mesna in deproteinized plasma and ascites using high-performance liquid chromatography with an electrochemical detector provided with a wall-jet gold electrode. RESULTS: After the i.v. administration of 41 g/m(2) BNP7787, BNP7787 and mesna had a half-life of 1.5 and 3.4 h, respectively. The AUC( infinity ) of mesna was approximately 8% of the AUC( infinity ) of BNP7787. Coadministration of cisplatin did not appear to influence the plasma concentration-time curves of BNP7787 and mesna. In ascites, approximately 0.02% of the BNP7787 dose was present as mesna, whereas approximately 4% of the dose was present as BNP7787 at the time of the maximum concentration. CONCLUSIONS: It can be concluded that the presence of ascites did not have a major impact on the pharmacokinetics of BNP7787 and coadministration of cisplatin did not influence the pharmacokinetics of BNP7787 and mesna.

Modulation of plasma thiols and mixed disulfides by BNP7787 in patients receiving paclitaxel/cisplatin therapy.

BACKGROUND: BNP7787 (disodium 2,2'-dithio-bis-ethane sulfonate) was evaluated in a phase I clinical trial with paclitaxel and cisplatin to assess the safety and potential efficacy for preventing or reducing cisplatin- and paclitaxel-induced toxicities. During this trial the effects of BNP7787 administration on the total concentrations (oxidized plus free) of cysteine, homocysteine and GSH in plasma, free and total GSH in WBC and rate of urinary excretion of cysteine were studied. The pharmacokinetics of ultrafilterable (free, non-protein bound) platinum were also determined after cisplatin (75 mg/m(2)) treatment which followed paclitaxel (175 mg/m(2)) and BNP7787 (8.2 to 27.6 g/m(2)). METHODS: Plasma thiols were measured by HPLC with fluorescence detection and platinum was measured by atomic absorption spectrophotometry. RESULTS: BNP7787 administration produced a significant depletion of all plasma thiols in all the patients studied. Differences were noted in the kinetics of BNP7787-induced depletion of cysteine and other thiols. A significant depletion of cysteine occurred with a time lag of about 2 h after the end of BNP7787 infusion, while a reversible depletion of GSH and homocysteine occurred immediately following the start of BNP7787 infusion, with the plasma thiol/disulfide nadir corresponding to the end of infusion. The mean half-life of cysteine depletion following BNP7787 administration was 2.2 h, significantly longer than for homocysteine (0.23 h), or GSH (0.18 h; P<0.05 for both). A several-fold increase in the urinary excretion of cysteine occurred following BNP7787 administration in all patients. The BNP7787-induced thiol/disulfide depletion in plasma was not affected by cisplatin administration ( P>0.05). BNP7787 administration had no effect on the ultrafilterable platinum pharmacokinetics. The 2-h lag in the depletion of cysteine, the most abundant thiol in plasma, suggests that the process may be related to the formation of free mesna from BNP7787 and that increased levels of mesna are not in circulation until after 2 h after BNP7787 administration. No effect of BNP7787 was seen on the GSH concentration in WBC, possibly reflecting the inability of these cells to take up BNP7787. CONCLUSION: The results suggest that BNP7787 has the potential to enhance cisplatin antitumor activity by depleting the reactive thiols in plasma.

Simultaneous determination of BNP7787 and its metabolite mesna in plasma and tissue by micro-HPLC with a dual electrochemical detector.

Sensitive, accurate, and precise assays are described to determine BNP7787 (disodium 2,2'-dithio-bis-ethane sulfonate) and its metabolite mesna (sodium 2-mercaptoethane sulfonate) simultaneously in plasma and tissue by micro-high-performance liquid chromatography (HPLC) with dual electrochemical detection. After separation of BNP7787 and mesna by micro-HPLC, the disulfide BNP7787 was reduced to mesna by a reactor cell with a glassy carbon working electrode (-1.6 V versus Hy-REF). At the second electrode, which consisted of a gold wall-jet electrode, the mesna generated from BNP7787 and the mesna already present in the samples were detected (+0.85 V versus Ag/AgCl). The lower limit of quantification (LLQ) of both compounds was 3 microM in plasma and 20 nmol/g in tissue. The dynamic range of the assay in plasma was 3-120 microM for mesna and 15-1200 microM for BNP7787. In tissue, the dynamic range was 20-2000 nmol/g for both compounds. The recovery of mesna from plasma and tissue ranged from 61.4 to 90.5% and 82.7 to 90.2%, respectively, and seemed to be concentration dependent. The recovery of BNP7787 from plasma and tissue was complete (i.e., 101.5 and 96.4%, respectively). The within- and between-day accuracy and precision for the plasma and tissue assay were within 14 and 7%, respectively. The utility of the assay was shown by determination of the stability of mesna and BNP7787 in a kidney sample of a rat and by analysis of plasma samples obtained from a patient receiving 18.4 g/m(2) BNP7787 as a 15-min intravenous infusion.

BNP7787, a novel protector against platinum-related toxicities, does not affect the efficacy of cisplatin or carboplatin in human tumour xenografts.

BNP7787 (2',2'-dithio-bis-ethane sulphonate sodium), a water-soluble disulphide, is chemically and mechanistically different from other sulphur-containing chemoprotective agents. Presently, BNP7787 is under investigation for its protective properties with regard to the side-effects of platinum compounds. In this study, we evaluated BNP7787, mesna and amifostine for their effects on the antitumour activity of platinum compounds. Continuous exposure to BNP7787 did not affect the antiproliferative effects of cisplatin or carboplatin, but the efficacy of both compounds was reduced in the presence of mesna in vitro in two human ovarian cancer cell lines. BNP7787 or amifostine combined with cisplatin or carboplatin given in standard schedules for the treatment of nude mice bearing well-established OVCAR-3 xenografts did not interfere with platinum-induced inhibition of tumour growth. Of interest, BNP7787 or amifostine co-administered with carboplatin was significantly more effective than carboplatin alone (P<0.01). In the presence of amifostine, doses of cisplatin and carboplatin could be safely increased by factors of 1.6 and 1.5, respectively. Unlike in a previous study of BNP7787 in tumour-bearing rats, BNP7787 did not protect against additional weight loss following treatment with higher doses of cisplatin in OVCAR-3-bearing mice. Pharmacokinetics of (mixed) disulphides including BNP7787 and extractable mesna in deproteinised plasma revealed a rapid disappearance of BNP7787 and an AUC(5-60) value of mesna 9-fold lower than that calculated after an equivalent dose of mesna by weight. We can conclude that BNP7787 does not interfere with the antitumour activity of platinum compounds in vitro and in vivo. Clinical trials are underway to evaluate the protection of normal tissues by BNP7787 when combined with cisplatin.

Quantification of BNP7787 (dimesna) and its metabolite mesna in human plasma and urine by high-performance liquid chromatography with electrochemical detection.

A sensitive and accurate assay was developed and validated to determine BNP7787 (dimesna), a new protector against cisplatin-induced toxicities, and its metabolite mesna in plasma and urine of patients. Both analytes were measured as mesna in deproteinized plasma or in urine diluted with mobile phase using high-performance liquid chromatography with an electrochemical detector provided with a wall-jet gold electrode. The assays for BNP7787 and mesna in deproteinized plasma were linear over the range of 1.6-500 microM and 0.63-320 microM, respectively. In plasma, the mean recovery of BNP7787 over the whole concentration range was 100.6% and of mesna 94.6%. The lower limits of quantitation (LLQs) of BNP7787 and mesna in deproteinized plasma were 1.6 microM and 0.63 microM, respectively. For both compounds the within- and between-day accuracy and precision of the assay was better than 12%. The assays for BNP7787 and mesna in urine were linear over the range of 0.8-1200 microM and 0.63-250 microM, respectively. In urine, the mean recovery of BNP7787 over the whole concentration range was 94.1% and of mesna 93.1%. The LLQ of BNP7787 in urine was 0.8 microM and of mesna 1.6 microM. The within- and between-day accuracy and precision of the assay for BNP7787 and mesna was lower than 15%. The stability of mesna in urine increased with an increasing concentration of mesna, lower temperature and addition of EDTA (1 g/l) and hydrochloric acid (0.2 M). BNP7787 in urine was stable for at least 24 h at temperatures in the range of -20 degrees C up to 37 degrees C and independent of the concentration. The developed assays are currently applied for samples of patients with solid tumors participating in a phase I trial of BNP7787 in combination with cisplatin.