An open-label, phase 2 trial of RPI.4610 (Angiozyme) in the treatment of metastatic breast cancer.

BACKGROUND: Serum and plasma levels of vascular endothelial growth factor (VEGF) correlate with prognosis in patients with metastatic breast cancer (MBC). VEGF binds to 2 receptors on endothelial cells, VEGFR-1 and VEGFR-2. RPI.4610 (Angiozyme0) is an antiangiogenic ribozyme targeting the VEGFR-1 mRNA. Preclinical and phase 1 studies suggested that RPI.4610 is a well-tolerated agent with clinical activity in solid tumors. The authors' trial evaluated the efficacy of RPI.4610 in the treatment of patients with progressive MBC. METHODS: This phase 2, multicenter, single-arm study was designed to assess the objective response rate of RPI.4610 in patients with MBC who had experienced disease progression with at least 1 course of chemotherapy for MBC. Patients received daily subcutaneous injections of RPI.4610 100 mg/m(2) for 12 weeks. RESULTS: Most patients (93%) had received at least 2 lines of chemotherapy previously; 69% of patients had received at least 3 lines of chemotherapy. Median follow-up was 2.76 months (range, 0.89-36.6 months). No partial responses nor complete responses were found. Median progression-free survival was 1.41 months (95% confidence interval [CI], 1.35-1.45). The median overall survival from start of treatment was 11.89 months (95% CI, 4.11-23.66). Treatment-related adverse events (AEs) were primarily grade 1 to 2 in intensity. Most common AEs were: injection site reactions, abdominal pain, anorexia, chromaturia, constipation, dyspnea, fatigue, headache, pain at the injection site, nausea, vomiting, and fever. CONCLUSIONS: Although RPI.4610 demonstrated a well-tolerated safety profile, its lack of clinical efficacy precludes this drug from further development.

Nucleic acids-based therapeutics in the battle against pathogenic viruses.

For almost three decades, researchers have studied the possibility to use nucleic acids as antiviral therapeutics. In theory, compounds such as antisense oligonucleotides, ribozymes, DNAzymes, and aptamers can be designed to trigger the sequence-specific inhibition of particular mRNA transcripts, including viral genomes. However, difficulties with their efficiency, off-target effects, toxicity, delivery, and stability halted the development of nucleic acid-based therapeutics that can be used in the clinic. So far, only a single antisense drug, Vitravene for the treatment of CMV-induced retinitis in AIDS patients, has made it to the clinic. Since the discovery of RNA interference (RNAi), there is a renewed interest in the development of nucleic acid-based therapeutics. Antiviral RNAi approaches are highly effective in vitro and in animal models and are currently being tested in clinical trials. Here we give an overview of antiviral nucleic acid-based therapeutics. We focus on antisense and RNAi-based compounds that have been shown to be effective in animal model systems.

Safety and efficacy assessment of chimeric ribozyme to proliferating cell nuclear antigen to prevent recurrence of proliferative vitreoretinopathy.

OBJECTIVE: To determine the safety and efficacy of VIT100 (Immusol, Inc, San Diego, California), a ribozyme to proliferating cell nuclear antigen, in preventing recurrent proliferative vitreoretinopathy (PVR) in patients with established PVR who undergo vitrectomy for retinal reattachment repair. METHODS: A multicenter, double-masked, placebo-controlled, randomized clinical trial. One hundred seventy-five eyes from 175 patients with grade C or worse PVR were randomly assigned to receive high-dose VIT100, low-dose VIT100, or placebo by intravitreal injection at the conclusion of retinal reattachment surgery. MAIN OUTCOME MEASURES: The primary efficacy end point was recurrent retinal detachment secondary to PVR. The secondary end point was recurrent retinal detachment due to any cause. RESULTS: One hundred fifty-four patients completed the study. Forty-one patients (27%) developed recurrent retinal detachment due to PVR by 24 weeks, including 18 patients (33%) in the group receiving 0.75 mg, 13 patients (24%) in the group receiving 0.15 mg, and 10 patients (22%) in the placebo group. There was no statistically significant difference in patients reaching this end point by 24 weeks (P = .37). Ancillary statistical analyses are reported. CONCLUSIONS: VIT100 was not effective in preventing PVR recurrence in patients with established grade C or worse PVR. APPLICATION TO CLINICAL PRACTICE: To our knowledge, this is the most recent, meticulously designed clinical trial in PVR.

A phase I clinical trial of a ribozyme-based angiogenesis inhibitor targeting vascular endothelial growth factor receptor-1 for patients with refractory solid tumors.

PURPOSE: This study intended to determine the maximum tolerated dose, safety, pharmacokinetic variables, clinical response, and pharmacodynamic markers of daily s.c. administration of Angiozyme. PATIENTS AND METHODS: Patients with refractory solid tumors were enrolled in a dose escalation and expanded cohort design. Dose escalation involved cohorts of patients at doses of 10, 30, 100, or 300 mg/m(2)/d for 29 days. A second component enrolled 15 additional patients at a daily dose of 100 mg/m(2). Patients were eligible to continue on therapy until disease progression. RESULTS: Thirty-one patients were enrolled and 28 were evaluable (range, 29-505 days; median, 89.5 days). A maximum tolerated dose was not defined by toxicity but rather by the maximal deliverable dose of 300 mg/m(2)/d. Grade 1 to 2 injection site reactions were the most common toxicities. One patient in the 300 mg/m(2) group experienced a reversible grade 3 injection site reaction. Angiozyme showed dose-dependent plasma concentrations with good bioavailability. Surrogate markers showed Angiozyme localization in tumor biopsies and a significant increase in serum von Willebrand factor antigen, a marker for endothelial cell dysfunction. Although Angiozyme-reactive antibody production was noted for some patients, no antibody-related adverse events were noted. Seven of 28 (25%) evaluable patients had stable disease for >or =6 months, with the longest treatment duration of > or =16 months. Two patients (nasopharyngeal carcinoma and melanoma) showed minor responses. CONCLUSION: Angiozyme was well tolerated with satisfactory pharmacokinetic variables for daily s.c. dosing. Results have provided the basis for subsequent clinical trials of this first-of-class biologically targeted therapeutic.

Safety and pharmacokinetic study of RPI.4610 (ANGIOZYME), an anti-VEGFR-1 ribozyme, in combination with carboplatin and paclitaxel in patients with advanced solid tumors.

PURPOSE: RPI.4610 (ANGIOZYME) is a chemically stabilized ribozyme targeting vascular endothelial growth factor receptor 1. The purpose of this study was to evaluate the safety and pharmacokinetics of RPI.4610 in combination with carboplatin and paclitaxel in patients with advanced solid tumors. METHODS: The study used a sequential treatment design evaluating a single dose level for all three drugs: paclitaxel 175 mg m-2 and carboplatin AUC=6 on day 1 of a 21-day cycle, and RPI.4610 100 mg m-2 day-1 beginning on day 8 and continuing daily thereafter. Pharmacokinetic samples were drawn on day 1 of courses 1 (chemotherapy alone) and 2 (chemotherapy+RPI.4610), and on day 8 of course 1 (RPI.4610 alone). Ratios were generated by comparing the pharmacokinetic parameters for the combination of carboplatin with paclitaxel when administered alone or together with RPI.4610. RESULTS: Twelve patients were enrolled in this trial and received two to six courses of treatment each. The most common grade 3-4 toxicities were neutropenia (three patients), thrombocytopenia (three patients), pain (three patients), anemia (two patients) and fatigue (two patients). The ratio of the mean maximum plasma concentration (Cmax) for carboplatin when administered with paclitaxel alone versus when administered with paclitaxel and RPI.4610 was 1.07 (90% confidence interval, 0.77-1.37). Similarly, the ratio of the mean AUC0-last for carboplatin was 1.04 (0.73-1.35). For paclitaxel the ratio of the mean Cmax when administered with carboplatin alone versus with carboplatin and RPI.4610 was 1.17 (1.03-1.31), and the ratio of the mean AUC0-last was 1.17 (1.04-1.30). Objective tumor responses were observed and included one patient with a complete response (bladder cancer) and one patient with a partial response (esophageal cancer). CONCLUSIONS: These results indicate that RPI.4610, carboplatin, and paclitaxel can be administered safely in combination without substantial pharmacokinetic interactions.

Safety evaluation of phosphodiesterase produced from Penicillium citrinum: summary of toxicological data.

The toxicity of Enzyme RP-1, an enzyme preparation used to hydrolyze yeast RNA to produce flavor enhancers for use in the food industry, was evaluated in a series of studies. A 5-week dietary toxicity study in Wistar rats was conducted in which animals received Enzyme RP-1 in feed at concentrations of 0, 500, 2000, or 8000 mg/kg body wt/day. A 13-week dietary toxicity study in Sprague-Dawley rats was conducted in which animals received RP-1 concentrate at 0, 0.125, 0.5, or 2% in their diets. At the highest dose levels in both studies, submandibular glands in the oral cavity were enlarged, an effect attributed to protease activity of the enzyme preparation. The no-observed-effect level in rats in the 13-week study was 0.5%, equivalent to 317 mg/kg body wt/day for males and 346 mg/kg body wt/day for females. Based on estimated dietary exposure to the enzyme preparation, the margin of exposure is estimated to be greater than 38,000. Lack of genotoxic potential was demonstrated by an in vitro reverse mutation assay in Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537 and in Escherichia coli strain WP2uvr and by an in vitro chromosome aberration test in CHL/IU cells derived from fibroblasts from the lungs of Chinese hamsters. Finally, the particular strain of Penicillium citrinum, the fungal strain used to prepare Enzyme RP-1, was shown to have low pathogenicity upon a single injection into the tail vein of rats of viable spores at doses up to 2.8x10(5) colony-forming units per animal. The results of these studies demonstrate that the enzyme preparation may be considered safe to workers and consumers when employed in the production of flavor enhancers from yeast.

Pharmacokinetics and tolerability of an antiangiogenic ribozyme (ANGIOZYME) in healthy volunteers.

The pharmacokinetics and tolerability of a chemically stabilized synthetic ribozyme (ANGIOZYME) targeting the Flt-1 VEGF receptor mRNA were evaluated in healthy volunteers. In a placebo-controlled, single-dose escalation study, ribozyme was administered as a 4-hour i.v. infusion of 10 or 30 mg/m2 or as a s.c. bolus of 20 mg/m2. Peak ribozyme plasma concentrations of 1.5 and 3.8 micrograms/mL were observed after the 10 and 30 mg/m2 i.v. infusions, respectively. When normalized to dose, AUC values as well as peak concentrations increased proportionally as the dose was increased from 10 to 30 mg/m2. Peak concentrations of 0.9 microgram/mL were observed approximately 3.25 hours after a 20 mg/m2 s.c. bolus of ribozyme. The dose-normalized AUCs obtained after s.c. dosing were compared to the mean dose-normalized AUC after i.v. dosing to estimate an absolute s.c. bioavailability (f) of approximately 69%. An average elimination half-life of 28 to 40 minutes was observed after i.v. administration, which increased to 209 minutes after s.c. administration. Only 4 of 12 reported adverse events were possibly related to administration of ribozyme (headache and somnolence). Thus, ribozyme administration was well tolerated after a single 4-hour i.v. infusion of up to 30 mg/m2 or a single s.c. bolus of 20 mg/m2.

The role of the toxicologic pathologist in the preclinical safety evaluation of biotechnology-derived pharmaceuticals.

Biotechnology-derived pharmaceuticals, or biopharmaceuticals, represent a special class of complex, high molecular weight products, such as monoclonal antibodies, recombinant proteins, and nucleic acids. With these compounds, it is not appropriate to follow conventional safety testing programs, and the preclinical "package" for each biopharmaceutical needs to be individually designed. In addition to standard histopathology, the use of molecular pathology techniques is often required either in conventional animal studies or in in vitro tests. In this review, the safety evaluation of biopharmaceuticals is discussed from the perspective of the toxicologic pathologist, and appropriate examples are given of the use of molecular pathology procedures. Examples include the use of in situ hybridization to localize gene therapy vectors, the assessment of vector integration into genomic DNA by the polymerase chain reaction (PCR), and the use of immunohistochemistry to evaluate the potential cross-reactivity of monoclonal antibodies. In situ PCR techniques may allow for confirmation of the germ cell localization of nucleic acids and may therefore facilitate the risk assessment of germline transmission. Increased involvement with biopharmaceuticals will present challenging opportunities for the toxicologic pathologist and will allow for much greater use of molecular techniques, which have a critical role in the preclinical development of these compounds.