Dose responsive effects of subcutaneous pentosan polysulfate injection in mucopolysaccharidosis type VI rats and comparison to oral treatment.

BACKGROUND: We previously demonstrated the benefits of daily, oral pentosan polysulfate (PPS) treatment in a rat model of mucopolysaccharidosis (MPS) type VI. Herein we compare these effects to once weekly, subcutaneous (s.c.) injection. The bioavailability of injected PPS is greater than oral, suggesting better delivery to difficult tissues such as bone and cartilage. Injected PPS also effectively treats osteoarthritis in animals, and has shown success in osteoarthritis patients. METHODOLOGY/PRINCIPAL FINDINGS: One-month-old MPS VI rats were given once weekly s.c. injections of PPS (1, 2 and 4 mg/kg, human equivalent dose (HED)), or daily oral PPS (4 mg/kg HED) for 6 months. Serum inflammatory markers and total glycosaminoglycans (GAGs) were measured, as were several histological, morphological and functional endpoints. Overall, weekly s.c. PPS injections led to similar or greater therapeutic effects as daily oral administration. Common findings between the two treatment approaches included reduced serum inflammatory markers, improved dentition and skull lengths, reduced tracheal deformities, and improved mobility. Enhanced effects of s.c. treatment included GAG reduction in urine and tissues, greater endurance on a rotarod, and better improvements in articular cartilage and bone in some dose groups. Optimal therapeutic effects were observed at 2 mg/kg, s.c.. No drug-related increases in liver enzymes, coagulation factor abnormalities or other adverse effects were identified following 6 months of s.c. PPS administration. CONCLUSIONS: Once weekly s.c. administration of PPS in MPS VI rats led to equal or better therapeutic effects than daily oral administration, including a surprising reduction in urine and tissue GAGs. No adverse effects from s.c. PPS administration were observed over the 6-month study period.

Pentosan polysulfate protects brain endothelial cells against bacterial lipopolysaccharide-induced damages.

Peripheral inflammation can aggravate local brain inflammation and neuronal death. The blood-brain barrier (BBB) is a key player in the event. On a relevant in vitro model of primary rat brain endothelial cells co-cultured with primary rat astroglia cells lipopolysaccharide (LPS)-induced changes in several BBB functions have been investigated. LPS-treatment resulted in a dose- and time-dependent decrease in the integrity of endothelial monolayers: transendothelial electrical resistance dropped, while flux of permeability markers fluorescein and albumin significantly increased. Immunostaining for junctional proteins ZO-1, claudin-5 and beta-catenin was significantly weaker in LPS-treated endothelial cells than in control monolayers. LPS also reduced the intensity and changed the pattern of ZO-1 immunostaining in freshly isolated rat brain microvessels. The activity of P-glycoprotein, an important efflux pump at the BBB, was also inhibited by LPS. At the same time production of reactive oxygen species and nitric oxide was increased in brain endothelial cells treated with LPS. Pentosan polysulfate, a polyanionic polysaccharide could reduce the deleterious effects of LPS on BBB permeability, and P-glycoprotein activity. LPS-stimulated increase in the production of reactive oxygen species and nitric oxide was also decreased by pentosan treatment. The protective effect of pentosan for brain endothelium can be of therapeutical significance in bacterial infections affecting the BBB.

Enhanced binding of modified pentosan polysulfate and heparin to bladder--a strategy for improved treatment of interstitial cystitis.

OBJECTIVES: To attach galactosyl residues to pentosan polysulfate (PPS) and heparin so that these drugs will bind to the endogenous lectins in the bladder. The increased binding may improve their efficacy for treating interstitial cystitis. METHODS: The anionic polysaccharides, PPS, and heparin were modified by attachment of lactose. The covalent modification was by chemical linking of lactose derivatives or by beta-lactosyl transfer reaction from p-nitrophenyl beta-lactoside using the transglycosylation activity of Trichoderma reesei cellulase enzymes. The unmodified and modified PPS and heparin, as well as various mucin glycoproteins, were radiolabeled or biotinylated and examined for their ability to bind to rabbit and human bladder. RESULTS: Both biotinylated and radiolabeled PPS and heparin bound very weakly or not at all to human and rabbit bladders. In contrast, the PPS and heparin modified by attachment of lactose, as well as the asialo mucin glycoproteins, bound strongly to human and rabbit bladders. This binding is apparently mediated by the interaction of the endogenous bladder galactins and the non-reducing galactose terminals in the lactose attached to the anionic polysaccharides or the asialoglycoproteins. CONCLUSIONS: Lactose-pentosan sulfate and lactose-heparin bind more avidly to the bladder epithelium than the unmodified molecules. Thus, they may be more effective for interstitial cystitis than the parent drugs. Other possible applications of this approach include modification of intravesical chemotherapeutic agents for bladder cancer, or intravesically placed antibiotics, to improve their adherence and retention in the bladder.

Metabolism of [3H]pentosan polysulfate sodium (PPS) in healthy human volunteers.

Pentosan polysulfate sodium (PPS) is the active ingredient in ELMIRON, a drug approved for the relief of bladder pain associated with interstitial cystitis. The study objective was to characterize the pharmacokinetic and metabolic profiles of PPS following oral dosing of [3H]PPS. As specific assays for PPS do not exist, metabolic profiling was accomplished through multiple fraction collections and radiochromatographic techniques. Two groups of eight healthy female subjects sequentially received a single oral dose of 200 microCi [3H]PPS supplemented with 300 mg unlabelled PPS or 300 microCi [3H]PPS supplemented with 450 mg unlabelled PPS. Most of the administered dose (84%) was excreted in faeces as intact PPS, and a smaller percentage (6%) was excreted in urine. In summary, orally administered PPS was very poorly absorbed, with the majority of the drug being excreted in faeces as intact PPS and in urine as low molecular weight and desulfated PPS.

Enhanced ileal absorption of a hydrophilic macromolecule, pentosan polysulfate sodium (PPS).

An in situ gelling, bioadhesive liquid formulation was developed to enhance the bioavailbility (BA) of a polysaccharide, pentosan polysulfate sodium (PPS). The formulation was tested to determine its bioavailability enhancement in a non-flush/non-ligated rat ileal model. A potent synergistic effect was found with a gelling agent Cremophor and a permeation enhancer sodium salicylate. The absolute bioavailabilities were 1.9%, 4.6%, 6.3% and 46.4%, respectively, for the PPS solution in saline, sodium salicylate/PPS, Cremophor/PPS and Cremophor/sodium salicylate/PPS. Therefore, we successfully demonstrated the approach of utilizing an in situ gelling/bioadhesive liquid carrier to enhancing the bioavailability of a hydrophilic macromolecule at the distal small intestine.

Lysosomal-storage disorder induced by elmiron following 90-days gavage administration in rats and mice.

Elmiron, a highly sulfated, semisynthetic pentose polysaccharide with properties similar to heparin, is used for the treatment of interstitial cystitis. Thirteen-week gavage studies were conducted by administering the drug in deionized water to F344/N rats and B6C3F1 mice once daily, 5 days per week for up to 13 consecutive weeks, at doses of 0, 63, 125, 250, 500, and 1,000 mg/kg body weight. No significant drug-related effects were observed in body weight, survival, clinical, and necropsy results. Significant organ weight increases were seen in the liver, lungs, and spleen of both species and the kidneys of rats, mainly in groups treated with 250 mg/kg/day and above. Hematological analysis indicated increases for both species in the white blood cell and lymphocyte counts. Sites of toxicity identified histopathologically were the rectum, liver, mesenteric and mandibular lymph nodes (both sexes), spleen (mice only), and lungs and kidneys (rats only). Lesions consisted mainly of infiltration into multiple tissues of vacuolated histiocytes, which, by histochemical investigation, indicated the presence of neutral and acidic mucins and lipidic material within the vacuoles. Transmission electron microscopy identified these vacuoles as lysosomal structures that exhibited a variety of contents. On the basis of our findings, we propose that Elmiron was absorbed through the focally disrupted rectal mucosa, was deposited in the lamina propria, accumulated within macrophages, and then was distributed by these cells or as a free chemical via the lymphatics and blood, to the various organ sites manifesting histiocytic infiltration. The cytoplasmic membrane-bound structures within macrophages were lysosomes containing membranous material of cellular origin and, perhaps, remnants of the deposited test material, Elmiron.

Effect of pentosan polysulfate therapy on intravesical potassium sensitivity.

OBJECTIVES: To evaluate further the intravesical potassium sensitivity test (PST) as an indicator of the epithelial leak of interstitial cystitis (IC) and determine whether successful pentosan polysulfate (PPS; Elmiron) treatment is associated with a change in PST results. Most individuals with IC appear to have an abnormally permeable epithelium that allows urinary solutes such as potassium to penetrate to the bladder interstitium, provoking symptoms. METHODS: Data were from an optimal dose trial of PPS in IC. Patients underwent a PST before and after a 32-week trial of 300, 600, or 900 mg PPS/day. The response to PPS treatment was measured using the Patient Overall Rating of Improvement in Symptoms scale. The before and after treatment PSTs and Patient Overall Rating of Improvement of Symptoms scores were compared. RESULTS: Of 377 patients with IC at 28 centers, 302 (80%) had a positive PST at entry. Of the 198 patients who completed the study, 153 were PST positive at entry and 92 (60%) showed clinical improvement at exit. Clinically improved patients had significant improvement on the PST analog pain and urgency scales (3.2 to 1.3 and 3.6 to 1.9, respectively; P <0.0001). In contrast, patients with no clinical improvement had no significant change in pain (3.1 to 2.7) or urgency (3.6 to 3.2). CONCLUSIONS: PST shows abnormal epithelial permeability in most patients with IC and a significant reduction in this permeability after successful PPS therapy. PST appears to be a valid indicator of epithelial abnormality and a reliable test in the diagnosis of IC.

Plasma and synovial fluid concentrations of calcium pentosan polysulphate achieved in the horse following intramuscular injection.

Results from in vitro studies have indicated that calcium pentosan polysulphate (CaPPS) may be of therapeutic value in osteoarthritis (OA) in the horse. However, no controlled clinical trials using this drug in equine OA have yet been reported. If CaPPS is to be developed for such use, the relationship between the proposed i.m. dose of CaPPS to be used and the concentrations of drug attained in plasma and synovial fluid of the target joint should first be established. An investigation was undertaken to determine these concentrations after a single 2 mg/kg i.m. injection of CaPPS. Blood and synovial fluid samples were taken from 6 healthy, sound horses following i.m. CaPPS administration. Concentrations of CaPPS measured in the synovial fluid were, on the basis of published studies, sufficient to elicit a potential therapeutic effect on synoviocyte metabolism, and possibly also to stimulate proteoglycan synthesis and reduce matrix metalloproteinase activities in articular cartilage. It would therefore seem justified to investigate further the therapeutic effect of CaPPS in OA in the horse.

The oral bioavailability of pentosan polysulphate sodium in healthy volunteers.

OBJECTIVE: Pentosan polysulphate sodium (PPS), a heparin-like drug, is supposed to be orally applicable. The objective of the present study was to assess the oral bioavailability of PPS. However, since specific assays for PPS do not exist, this was done by using primary and secondary effect parameters. METHODS: The study was carried out using a three-way randomized crossover design with 18 healthy young male volunteers. The subjects received three treatments: PPS i.v. (50 mg), PPS orally (1500 mg) and placebo (orally). Blood sampling was done for activated partial thromboplastin time (APTT), anti-Xa activity, hepatic triglyceride lipase, lipoprotein lipase, tissue plasminogen activator (t-PA) activity, fibrin plate lysis, total triglyceride, total cholesterol, HDL and LDL. RESULTS: Intravenously administered PPS significantly increased APTT, anti-Xa activity, hepatic triglyceride lipase and lipoprotein lipase compared with placebo in a magnitude comparable to other i.v. heparin-like compounds. Orally administered PPS did not significantly influence any of the parameters when compared with placebo. Point estimates for the oral bioavailability of PPS were in the range of 0% with small confidence intervals (CIs). CONCLUSION: The oral bioavailability of PPS is negligible in young healthy males.

Slow-acting, disease-modifying osteoarthritis agents.

There is evidence to suggest that tetracyclines have benefit beyond their antimicrobial activity. The ability to inhibit metalloproteinase activity may provide a disease-modifying effect in OA, and available data suggest that further investigation is warranted. Controlled, double-blind, prospective clinical studies have not been completed. The canine cruciate ligament transection model studies are frequently cited as the most convincing in vivo evidence of a benefit of oral tetracycline therapy for the treatment of OA. Until more evidence becomes available, the use of tetracyclines as therapeutic agents for OA should be considered investigational.

Phase I trial of orally administered pentosan polysulfate in patients with advanced cancer.

Tumor angiogenesis is critically important to tumor growth and metastasis. We have shown that pentosan polysulfate (PPS) is an effective inhibitor of heparin-binding growth factors in vitro and can effectively inhibit the establishment and growth of tumors in nude mice. Following completion of our Phase I trial of s.c. administered PPS, we performed a Phase I trial of p.o. administered PPS in patients with advanced cancer to determine the maximum tolerated dose (MTD) and toxicity profile and to search for any evidence for biological activity in vivo. Patients diagnosed with advanced, incurable malignancies who met standard Phase I criteria and who did not have a history of bleeding complications were enrolled, in cohorts of three, to receive PPS p.o. t.i.d., at planned doses of 180, 270, 400, 600, and 800 mg/m2. Patients were monitored at least every 2 weeks with physical exams and weekly with hematological, chemistry, stool hemoccult, and coagulation blood studies, and serum and urine samples for PPS and basic fibroblastic growth factor (bFGF) levels were also taken. The PPS dose was escalated in an attempt to reach the MTD. Eight additional patients were enrolled at the highest dose to further characterize the toxicity profile and biological in vivo effects of PPS. A total of 21 patients were enrolled in the three cohorts of doses 180 (n = 4), 270 (n = 3), and 400 (n = 14) mg/m2. The most severe toxicities seen were grade 3 proctitis and grade 4 diarrhea; however, 20 of the 21 patients had evidence of grade 1 or 2 gastrointestinal (GI) bleeding. These toxicities became evident at a much earlier time point as the dose was increased, but their severities were similar at all dose levels. There were no objective responses, although three patients had prolonged stabilization of previously progressing disease. Pharmacokinetic analysis suggested marked accumulation of PPS upon chronic administration. Serum and urine bFGF levels failed to show a consistent, interpretable pattern; however the data suggested an inverse relationship between PPS and bFGF levels in vivo. A MTD could not be determined using the daily t.i.d. dosing schedule due to the development of grade 3/4 GI toxicity (proctitis) at all dose levels studied. PPS, administered p.o. at doses of 400 mg/m2 t.i.d., did not cause significant systemic toxicity, but most patients developed moderate-to-severe GI toxicity within 1-2 months. The cause of the GI toxicity was unclear, but it was readily reversible upon cessation of the agent. The suggestion of an inverse relationship between PPS and bFGF supports further study of PPS as an antiangiogenic agent. The tested doses and schedule cannot be recommended for further study. Subsequent murine experiments showed PPS to be more effective as an anticancer agent when it is given intermittently. We propose a study of PPS given on a weekly schedule in further clinical trials.

Effects of a beta-human chorionic gonadotropin subunit immunogen administered in aqueous solution with a novel nonionic block copolymer adjuvant in patients with advanced cancer.

The clinical and immunological effects of a vaccine consisting of CTP37, a synthetic peptide corresponding to the COOH-terminal peptide (CTP) of beta-human chorionic gonadotropin (beta-hCG) conjugated to diphtheria toxoid, combined with CRL 1005, a novel synthetic nonionic block copolymer adjuvant, were examined. Twenty-one patients with metastatic, nontrophoblastic cancers received up to four immunizations by i.m. injection of a fixed dose of CTP37 and escalating doses of CRL 1005. Doses of CRL 1005 adjuvant as high as 75 mg were administered with 1 mg of CTP37 without evidence of significant local or systemic toxicity. Immunizations resulted in the production of IgG antibody to beta-hCG. CRL 1005 doses of 3-25 mg appeared to be optimal for antibody induction. Immunizations also resulted in increases in the cellular response of peripheral blood mononuclear cells (PBMCs) to the unconjugated CTP, hCG, and diphtheria toxoid. Responding PBMCs specifically secreted the TH1-associated cytokines IFN-gamma and interleukin (IL)-2 as well as the TH2-associated IL-5 and IL-10. Increased expression of IFN gamma and IL-5 mRNAs by PBMCs 4 h after immunization was also observed. CRL 1005 administered with CTP37 in aqueous solution is well tolerated. The CTP37-CRL 1005 subunit vaccine has the capacity to stimulate potentially beneficial humoral and cellular immune responses in patients with advanced cancer.

Administration of pentosan polysulfate to patients with human immunodeficiency virus-associated Kaposi's sarcoma.

BACKGROUND: Neovascularization induced by basic fibroblast growth factor (basic FGF) or FGF-like cytokines is thought to play a substantial role in the pathogenesis of human immunodeficiency virus (HIV)-associated Kaposi's sarcoma. Pentosan polysulfate has been shown to inhibit basic FGF and FGF-like dependent tumor growth both in vitro and in vivo. Moreover, it has been found to inhibit the growth of Kaposi's sarcoma-derived spindle cells in vitro. These observations suggested that pentosan polysulfate might be worth exploring as a potential agent for the treatment of Kaposi's sarcoma. PURPOSE: The purpose of this phase 1 clinical trial was to determine the maximum tolerated dose of pentosan polysulfate in patients with HIV-associated Kaposi's sarcoma and whether or not this compound had activity against this neoplasm. METHODS: Sixteen HIV-seropositive patients with Kaposi's sarcoma received pentosan polysulfate via continuous venous infusion for 3-6 weeks and then received a subcutaneous dose three times per week. Three different doses of pentosan polysulfate were administered: 2 mg/kg per day by infusion followed by 2 mg/kg per dose given subcutaneously (six patients), 3 mg/kg per day by infusion followed by 3 mg/kg per dose given subcutaneously (five patients), and 4 mg/kg per day by infusion followed by 4 mg/kg per dose given subcutaneously (five patients). Five of the 16 patients in the study also received injections of 1 mg of pentosan polysulfate into two different lesions two times a week for 3 weeks, followed by intralesional therapy once weekly. After receiving pentosan polysulfate for 6 weeks, patients were administered 100 mg zidovudine (AZT) orally every 4 hours in conjunction with pentosan polysulfate. RESULTS: The maximally tolerated dose of pentosan polysulfate given by continuous venous infusion was found to be 3 mg/kg per day. No patient had an objective clinical antitumor response to either systemic or intralesional pentosan polysulfate administration; however, three patients had stable Kaposi's sarcoma for 3-27 weeks. No statistically significant effect on CD4 cells or serum HIV p24 antigen was noted during pentosan polysulfate administration. Dose-limiting toxic effects were characterized by anticoagulation and thrombocytopenia and were reversible. CONCLUSION: Pentosan polysulfate was well tolerated in this patient population. However, no objective tumor response or evidence of anti-HIV activity was noted; therefore, no claim of activity can be made in this trial. IMPLICATION: Continued investigation into the use of angiogenesis inhibitors with improved activity and toxicity profiles or different mechanisms of action is warranted.