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Functional proteomic screens in therapeutic protein drug discovery.

Biopharmaceuticals, mainly protein-based therapeutics, are rapidly being developed for several disease indications. However, most biopharmaceuticals are 'me-too' drugs or are being developed against the same handful of targets. Thus, the potential of biopharmaceuticals is not being fully exploited. The bottleneck is still the lack of validated targets and the means of implementing the appropriate target validation technology. Functional proteomic screens provide a rapid route to accelerate the discovery and development of the next generation of biopharmaceuticals.

Antibodies↗

Discovery pharmaceutics--challenges and opportunities.

Most pharmaceutical companies are now evaluating compounds for druglike properties early in the discovery process. The data generated at these early stages allow upfront identification of potential development challenges and thus selection of the best candidates for lead nomination. Most often, lead nomination candidates are selected based on pharmacological and toxicological data. However, many drugs in development suffer from poor biopharmaceutical properties due to suboptimal physiochemical parameters. The poor biopharmaceutical properties often lead to extended timelines and a higher cost of developing the compounds. To avoid these problems and choose the best compounds from a biopharmaceutical perspective, physicochemical parameters such as solubility, lipophilicity, and stability need to be evaluated as early as possible. Furthermore, the preformulation approaches used to evaluate the compounds for their pharmacokinetic and toxicological properties need to be optimized. This minireview summarizes some of the parameters and approaches that can be used to evaluate compounds in the early stages of drug discovery.

Biopharmaceutics↗

Virtual screening of intestinal drug permeability.

Lead compounds generated in high throughput drug discovery programmes often have unfavorable biopharmaceutical properties, resulting in a low success rate of such drug candidates in clinical development. Drug companies and researchers would thus like to have methods of predicting biopharmaceutical properties accurately. The intestinal permeability to a lead compound is one such property which is particularly important. Therefore, access to methods to accurately predict biopharmaceutical properties, such as the intestinal permeability of a large series of compounds, is of particular importance. This review deals with new theoretical methods used to predict intestinal drug permeability. There are several possible transport routes across the intestine, but theoretical methods generally deal with only one of them, the passive transcellular route. Therefore, this review will also discuss the relative importance of passive and active drug transport and efflux routes using recent data generated in cell cultures, animal models and human subjects.

Animals↗

Large scale production of recombinant human lactoferrin in the milk of transgenic cows.

The limited capacity of current bioreactors has led the biopharmaceutical industry to investigate alternative protein expression systems. The milk of transgenic cattle may provide an attractive vehicle for large-scale production of biopharmaceuticals, but there have been no reports on the characteristics of such recombinant proteins. Here we describe the production of recombinant human lactoferrin (rhLF), an iron-binding glycoprotein involved in innate host defense, at gram per liter concentrations in bovine milk. Natural hLF from human milk and rhLF had identical iron-binding and -release properties. Although natural hLF and rhLF underwent differential N-linked glycosylation, they were equally effective in three different in vivo infection models employing immunocompetent and leukocytopenic mice, and showed similar localization at sites of infection. Taken together, the results illustrate the potential of transgenic cattle in the large-scale production of biopharmaceuticals.

Animals↗

Appropriate specifications at the IND stage.

Biopharmaceutical product specifications are to be "scientifically sound and appropriate". However, how does a biopharmaceutical company determine what are acceptable specifications for its product at the early stages of clinical development? Are there really enough test data at the start of the IND trials to "establish" specifications? As an industry, are we doing too many tests at the IND stage (i.e. following the "must do every test on someone's published list" syndrome), and then finding that specifications need to be set for each test we run? Are we feeling pressurised (either by regulatory agencies or by our own corporate cultures) to set unrealistic and tight specifications at the IND stage, and then later regretting how to justify loosening them when we gain more experience with the release testing or stability of our products? A discussion on how to set practical product specifications for biopharmaceutical products at the IND stage is presented.

Biopharmaceutics↗

Densonucleosis virus purification by ion exchange membranes.

Preparative chromatography is widely used in the downstream purification of biopharmaceutical products. Replacement of resins by membranes as chromatographic supports, overcomes many of the limitations associated with resin-based chromatography such as high-pressure drops, slow processing rates due to pore diffusion and channeling of the feed through the bed. In particular, adsorptive membranes may be ideally suited for virus capture. Virus capture is critical in a number of applications. In gene therapy and vaccine production, large-scale purification of virus vectors is often essential. In the manufacture of biopharmaceuticals, validation of virus clearance is critical. Here results for purification of Aedes aegypti densonucleosis virus (AeDNV) using anion and cation exchange membranes are presented. AeDNV is a non-enveloped, single-stranded mosquito-specific parvovirus. Virus particles are around 20 nm in size. AeDNV could find potential applications in integrated vector-borne disease control programs. In addition, capture of parvovirus for validation of virus clearance in the manufacture of biopharmaceuticals is of commercial importance. By adjusting the pH of the feed stream, AeDNV particles may be adsorbed by both anion and cation exchange membranes. However, strongly basic anion exchange membranes were the most effective in adsorbing AeDNV particles. Adsorption and subsequent elution of AeDNV by anion exchange membranes leads to significant virus concentration. Dynamic and static capacities for anion exchange membranes were similar. Further, a sharp elution curve was obtained suggesting that pore diffusional resistances are insignificant. The adsorption of AeDNV particles by anion exchange membranes may be described by a linear isotherm.

Chromatography, Ion Exchange↗

A statistical method for the determination of absorption rate constant estimated using the rat single pass intestinal perfusion model and multiple linear regression.

The guide "Waiver of In Vivo Bioavailability and Bioequivalence Studies for Immediate Release Solid Dosage Forms Containing Certain Active Moieties/Active Ingredients Based on a Biopharmaceutical Classification System" (Rockville, MD: CDER, 2000) outlined non-in vivo tests of permeability that may satisfy the classification of a compound in the biopharmaceutical classification system. However, absent from that document were specific statistical methods to legitimatize the non-in vivo tests. This report describes the appropriate statistical treatment of absorption data, and recommends its adoption in the estimation of absorption and/or permeability measurements. The calculation of the absorption rate constants (k(a)) of ten compounds by a new multiple linear regression (MLR) method was completed after the separate perfusion of each compound through the rat single pass intestinal perfusion model (n = 3 rats per compound). Studentized residuals were evaluated to determine whether any statistically significant outliers were present in the data. The standard error of k(a) was estimated using variance components from the random effects model. The results were compared with the "traditional method" for k(a) calculations. Although both methods produced similar values of k(a), the MLR method's error estimate included multiple components of variability, which was largely ignored by the traditional method. The MLR method provided objective tests for outliers and achievement of steady-state. A preferred method for the statistical analysis of absorption data was demonstrated. These methods should be applied to all forms of permeability measurements, especially the non-in vivo measurements that classify a compound in the biopharmaceutical classification system.

Absorption↗

Protect from light: photodegradation and protein biologics.

The exposure of proteins to light and the ensuing chemical and physical degradation has been studied extensively for many years. The residues in proteins that undergo primary photooxidation include tryptophan, tyrosine, phenylalanine, and cysteine/cystine. While photooxidation has been recognized as a major contributor to protein degradation, the effects of photoinduced damage have not been widely studied for biopharmaceuticals. This is particularly important since photodegradation can lead to changes in primary, secondary, and tertiary structures of protein and these changes, while not definitively established, could lead to differences in long-term stability, bioactivity, or immunogenicity. In this review we briefly describe the major pathways of photodegradation for proteins followed by a description of the limited data on photodegradation of biopharmaceuticals and methods that have been used to reduce or prevent damage. It is our intent to spur additional research in this area for increasing the safety and effectiveness of biopharmaceutical products.

Biological Products↗

Proteomic studies support the use of multi-product immunoassays to monitor host cell protein impurities.

In the biopharmaceutical industry, recombinant protein drugs are commonly produced in Chinese hamster ovary (CHO) cells. During the development process, removal of CHO cell-derived proteins from the biopharmaceutical product is monitored using multi-product immunoassays. Such immunoassays are developed by raising antibodies to a single CHO cell protein preparation. However, these assays are utilized to monitor CHO cell protein impurities during the recovery of products from different CHO cell lines. To address whether underlying differences between CHO cell lines result in sufficient protein expression changes to exclude the suitability of multi-product immunoassays, a comparative proteomics study of three independently generated CHO cell lines was performed. Statistical analysis of over 1000 proteins resolved by 2-D PAGE demonstrated that the protein expression profiles of three different CHO cell lines exhibit very few differences in protein expression. Only 11 qualitative changes in protein expression and 26 quantitative changes greater than two-fold were observed. Identification of protein spots by mass spectrometry revealed that many of the observed changes were due to post-translational modifications rather than expression of novel proteins in each cell line. These results suggest that multi-product immunoassays are suitable for monitoring host cell proteins in biopharmaceuticals produced in different CHO cell lines.

Animals↗

A strategy for preclinical formulation development using GastroPlus as pharmacokinetic simulation tool and a statistical screening design applied to a dog study.

The aim of this paper is to propose a pharmaceutical risk assessment strategy that goes beyond the usual characterisation of a clinical candidate molecule according to the biopharmaceutical classification system (BCS). This strategy was evaluated for a new CNS drug with poor solubility and good permeability. In a first step, GastroPlus was used to simulate the absorption process based on preformulation data. These input data involved a physicochemical drug characterisation including drug solubility measurements in simulated physiological media, as well as permeability determination. Further computer simulations were conducted to determine the sensitivity to changes of selected input values. Thus, oral bioavailability prediction was studied as a function of the particle size and drug solubility. The second part of the presented strategy for preclinical formulation development was to test specially designed formulations in a 2(3) screening factorial plan using the dog as the animal model. The factors were the dosage form, food effect and dose strength. One of the two experimental formulations was a capsule filled with the micronised drug, whereas the other formulation was a surfactant solution of the drug. Accordingly, a "worst case" formulation was compared with a "best case" drug solution over the clinically relevant dose range in fasted and fed dogs. The results of the computer simulation indicated that a fraction of the dose is dissolved in the stomach and precipitates partially in the small intestine. The simulation predicted almost full drug absorption during the GI transit time. Interestingly, the simulation implies that stomach drug solubility had little impact on overall fraction absorbed. The results also showed that changes of particle size and reference solubility within two orders of magnitude hardly affected the oral bioavailability. This in silico deduction was subsequently compared with the results of the dog studies. Indeed a surfactant drug solution showed no clear biopharmaceutical superiority over a solid capsule formulation on the average of both dose strengths in fasted and fed dogs. Despite the substantial variability of the in vivo data, the factorial screening design indicated marginal significant interaction between the dose level and feeding status. This can be viewed as a flag for the planning of further studies, since a potential effect of one factor may depend on the level of the other. In summary, the GastroPlus simulation together with the statistically designed dog study provided a thorough biopharmaceutical assessment of the new CNS drug. Based on these findings, it was decided to develop a standard granulate in capsules for phase I studies. More sophisticated formulation options were abandoned and so the clinical formulation development was conducted in a cost-efficient way.

Administration, Oral↗

Decision-support tool for assessing biomanufacturing strategies under uncertainty: stainless steel versus disposable equipment for clinical trial material preparation.

This paper presents the application of a decision-support tool, SIMBIOPHARMA, for assessing different manufacturing strategies under uncertainty for the production of biopharmaceuticals. SIMBIOPHARMA captures both the technical and business aspects of biopharmaceutical manufacture within a single tool that permits manufacturing alternatives to be evaluated in terms of cost, time, yield, project throughput, resource utilization, and risk. Its use for risk analysis is demonstrated through a hypothetical case study that uses the Monte Carlo simulation technique to imitate the randomness inherent in manufacturing subject to technical and market uncertainties. The case study addresses whether start-up companies should invest in a stainless steel pilot plant or use disposable equipment for the production of early phase clinical trial material. The effects of fluctuating product demands and titers on the performance of a biopharmaceutical company manufacturing clinical trial material are analyzed. The analysis highlights the impact of different manufacturing options on the range in possible outcomes for the project throughput and cost of goods and the likelihood that these metrics exceed a critical threshold. The simulation studies highlight the benefits of incorporating uncertainties when evaluating manufacturing strategies. Methods of presenting and analyzing information generated by the simulations are suggested. These are used to help determine the ranking of alternatives under different scenarios. The example illustrates the benefits to companies of using such a tool to improve management of their R&D portfolios so as to control the cost of goods.

Clinical Trials as Topic↗

The milk protein promoter is a useful tool for developing a rat with tolerance to a human protein.

Biopharmaceuticals intended for humans are immunogenic in animals. Antibodies associated with their administration make it difficult to perform repeated-dose pharmacology and toxicology studies in animals. Despite suggestions to solve this problem with transgenic animal technology, an effective strategy has not yet been reported. The objective of the present study was to provide an efficient strategy to develop rats tolerant to biopharmaceuticals such as human gene-based proteins. The present study used transgenic rat lines (lines 311-6, 308-5, and 305-1) carrying a fusion gene designed to express the human growth hormone (hGH) gene under the control of the bovine alphaS1 casein gene promoter. Three lactating females with the transgene, produced approximately 4 mg/ml, 300 microg/ml, and 10 ng/ml in their milk. Male 8-week-old rats from these three lines were immunized with hGH three times (week 0, 1, and 3 ) and the production of antibodies against hGH in their sera were examined at week 4. While the hGH serum antibody titers increased over 1000-fold in wild-type control rats, there was no detectable antibody against hGH in the sera of these three transgenic lines. Human growth hormone in their sera was undetectable (lines 308-5 and 305-1) or much lower than the endogenous biologic level of rat growth hormone (line 311-6). Importantly, lines 308-5 and 305-1 developed tolerance to hGH without detectable hGH in their sera and these lines will be very useful for the repeated dose pharmacology and toxicology studies. These results suggest that a milk protein promoter can be a useful tool to develop transgenic rats that are tolerant to biopharmaceuticals intended for humans.

Animals↗

Follow-on biologics: challenges of the "next generation".

The imminent patent expiration of many biopharmaceutical products will produce the possibility for generic versions of these therapeutic agents (i.e. biosimilars). However, there are a number of issues that will make approval of biosimilars much more complicated than the approval of generic equivalents of conventional pharmaceuticals. These issues centre on the intrinsic complexity of biopharmaceutical agents, which are recombinant proteins in most cases, and the heterogeneity of proteins produced by different manufacturing processes (i.e. differences in host cells, purification and processing, formulation and packaging). The increased occurrence of antibody (Ab)-mediated pure red cell aplasia (PRCA) associated with a change in the formulation of one particular epoetin-alpha product highlights the potential for increased immunogenicity of recombinant proteins with different formulations, or those manufactured by different processes. Thus, verification of the similarity to or substitutability of biosimilars with reference innovator biopharmaceutical products will require much more than a demonstration of pharmacokinetic similarity, which is sufficient for conventional, small molecule generic agents. Regulatory requirements for the approval of biosimilars have not yet been fully established, but preliminary guidelines from the European Agency for the Evaluation of Medicinal Products (EMEA) state that the complexity of the product, the types of changes in the manufacturing process, and differences in quality, safety and efficacy must be taken into account when evaluating biosimilars. For most products, results of clinical trials demonstrating safety and efficacy are likely to be required. In addition, because of the unpredictability of the onset and incidence of immunogenicity, extended post-marketing surveillance is also important and may be required.

Antibodies↗

Preclinical development of keliximab, a Primatized anti-CD4 monoclonal antibody, in human CD4 transgenic mice: characterization of the model and safety studies.

The preclinical safety assessment of biopharmaceuticals necessitates that studies be conducted in species in which the products are pharmacologically active. Monoclonal antibodies are a promising class of biopharmaceuticals for many disease indications; however, by design, these agents tend to have limited species cross-reactivity and tend to only be active in primates. Keliximab is a human-cynomolgus monkey chimeric (Primatized) monoclonal antibody with specificity for human and chimpanzee CD4. In order to conduct a comprehensive preclinical safety assessment of this antibody to support chronic treatment of rheumatoid arthritis in patients, a human CD4 transgenic mouse was used for chronic and reproductive toxicity studies and for genotoxic studies. In addition, immunotoxicity studies were conducted in these mice with Candida albicans, Pneumocystis carinii and B16 melanoma cells to assess the effects of keliximab on host resistance to infection and immunosurveillance to neoplasia. The results of these studies found keliximab to be well tolerated with the only effects observed being related to its pharmacologic activity on CD4+ T lymphocytes. The use of transgenic mice expressing human proteins provides a useful alternative to studies in chimpanzees with biopharmaceutical agents having limited species cross-reactivity.

Animals↗

Influence of pharmaceutical quality on the bioavailability of active components from Ginkgo biloba preparations.

To be effective, herbal medicinal products are expected to meet comparable standards concerning the assessment of efficacy, safety and biopharmaceutical quality as chemically defined synthetic drugs as food supplements. However, these requirements are often not fulfilled, particularly regarding the characterization of biopharmaceutical properties such as in-vitro dissolution and in-vivo bioavailability. With respect to the relevance of biopharmaceutical quality of herbal medicinal products, two different Ginkgo biloba brands (test product: Ginkgo biloba capsules; reference product: Ginkgold) were analysed for dissolution rates and bioavailability of the most relevant active ingredients. Dissolution rates at pH 1 and 4.5 were determined according to the USP 23. The relative bioavailability of ginkgolide A, ginkgolide B and bilobalide was investigated after single oral administration of 120 mg Ginkgo biloba extract as tablets or capsules. Bioavailability data (area under the curve and peak concentration in plasma) were clearly different and did not show bioequivalence of test and reference products. The slow in-vitro dissolution of the test product resulted in a large decrease in bioavailability. These results indicate for the first time that the pharmaceutical properties of a herbal medicinal product have a significant impact on the rate and extent of drug absorption, and very likely on efficacy in humans.

Administration, Oral↗

Transgenic plant-derived pharmaceuticals - the practical approach?

Production of biopharmaceuticals in transgenic plants would involve the creation of a new industry. Those transgenic plants, including staple food crops, could provide many benefits to people all over the world. However, the new industry might require a strict regulation system. It is probable that such a strict system would not be acceptable to Japan or to most developing countries. Many countries should use non-food crops for production of biopharmaceuticals and take on more simple systems. The new industry must develop strategies for promoting the benefits of transgenic plant-derived biopharmaceuticals on both the domestic and worldwide scales.

Animals↗

ALX 111: ALX1-11, parathyroid hormone (1-84) - NPS Allelix, PREOS, PTH, recombinant human parathyroid hormone, rhPTH (1-84).

ALX 111 [parathyroid hormone (1-84) - NPS Allelix, recombinant human parathyroid hormone, rhPTH (1-84), PREOS] is a full-length, recombinant human parathyroid hormone. It has potential as an anti-osteoporotic agent, due to its properties as a bone formation stimulant. This profile has been selected from R&D Insight, a pharmaceutical intelligence database produced by Adis International Ltd. It has been recommended that ALX 111 should be given for 1 to 2 years and may be given in combination with an antiresorptive agent, such as estrogen or a bisphosphonate. In December 1999, Allelix Biopharmaceuticals merged with NPS Pharmaceuticals. This combined company is operating as NPS Pharmaceuticals in the US and as NPS Allelix in Canada. The merger has enabled a phase III study of ALX 111 to begin in the US, Europe and South America. NPS harmaceuticals has signed an agreement with Bio-Imaging Technologies, which will provide all image handling and analysis for this trial. Until 1994, Allelix Biopharmaceuticals and Glaxo in Canada were involved in a joint venture to investigate the efficacy of ALX 111 in osteoporosis. Allelix was subsequently, until September 1998, collaborating with Astra of Sweden in developing ALX 111. Astra had acquired exclusive worldwide rights to ALX 111 and was responsible for development of the agent. However, Astra returned all rights to ALX 111 to Allelix as a result of its merger with Zeneca to form AstraZeneca. In December 1999, Allelix Biopharmaceuticals merged with NPS Pharmaceuticals. This combined company is operating as NPS Pharmaceuticals in the US and as NPS Allelix in Canada. The merger has enabled a phase III study of ALX 111 to begin in the US, Europe and South America. The phase III trial of ALX 111 for the treatment of osteoporosis has completed patient enrolment, and phase II trials have been completed in Canada and the Netherlands. The 18-month, phase III, multicentre, placebo-controlled trial (Treatment of Osteoporosis with Parathyroid Hormone; TOP) has been designed to assess the bone-building and fracture-reducing potential of the drug, and over 2600 postmenopausal women with osteoporosis who have not received previous drug therapy for osteoporosis have been enrolled. Treatment will be completed in September 2003, but more than 75% of patients enrolled in the TOP study have chosen to enrol in an Open Label Extension Study (OLES), which allows for a total treatment period of up to 24 months. NPS Pharmaceuticals has signed an agreement with Bio-Imaging Technologies, which will provide all image handling and analysis for this trial. In September 2002, NPS Pharmaceuticals announced that it has met its patient enrolment target (n > 150) for its POWER (PTH for Osteoporotic Women on Estrogen Replacement) study; a 24-month phase III trial initiated in Europe in November 2001. In this trial, women with osteoporosis receive SC injections of ALX 111 or placebo, in combination with their existing hormone replacement therapies, to test the bone building potential of the drug. In addition to the POWER study, a clinical trial sponsored by the National Institutes of Health (NIH) is being conducted to evaluate the potential of ALX 111 to build bone in combination with another osteoporosis medication. The 'PaTH' study (PTH/alendronate) is designed to assess the effect of various combinations and sequential uses of ALX 111 and Merck's Fosamax, a drug for slowing the loss of bone due to osteoporosis. The PaTH study, initiated in May 2000 and scheduled to conclude in September 2003, involved 238 patients with postmenopausal osteoporosis. It is thought that alendronic acid and ALX 111, when administered in combination, may act in an additive manner to treat osteoporosis because they act in different ways; alendronic acid acts to inhibit resorption and ALX 111 speeds up bone formation and resorption, with a net increase in formation. Results of this study are still being analysed but preliminary results appear to be positive. The effect of ALX 111 on bone cell cultures underare still being analysed but preliminary results appear to be positive. The effect of ALX 111 on bone cell cultures under conditions of microgravity was tested in orbit on the Space Shuttle Columbia, which was launched on 16 January 2003 but did not survive re-entry. This study was one in a series of studies known as 'OSTEO' and had been prepared by researchers from NPS Pharmaceuticals using Millenium Biologix' OSTEO Mini-Lab System. Under space flight conditions, astronauts experience a loss in bone density at a rate up to ten times faster than that of earth-bound patients with osteoporosis, and it was hoped that this study would indicate the mechanism of action of ALX 111 at cellular and genetic levels. The results of these studies were represented by the samples of human bone cells, which were lost during the re-entry tragedy.

Bone Density↗

Staphylococcus aureus vaccine conjugate--Nabi: Nabi-StaphVAX, StaphVAX.

Staphylococcus aureus is a major cause of hospital-acquired infections and infections in kidney dialysis patients. Over 90% of these infections are due to types 5 and 8. Nabi, under a CRADA agreement with the US National Institutes of Health, is developing a bivalent vaccine against S. aureus types 5 and 8 [Nabi-StaphVAX, StaphVAX]. The vaccine contains type 5 and type 8 S. aureus capsular polysaccharides conjugated to a protein carrier (recombinant exoprotein A, a genetically detoxified form of Pseudomonas aeruginosa exotoxin A). Nabi changed its name to Nabi Biopharmaceuticals on 5 March 2002. StaphVAX is available for licensing (http://www.nabi.com). Nabi's preference is for a licensee that can provide non-US marketing and regulatory capabilities in addition to financial resources to accelerate the vaccine's development. Nabi intends to develop a second-generation version of StaphVAX that will include antigen from Staphylococcus type 336. This would increase the vaccine's coverage of staphylococcal infection. Nabi also intends to develop two combination vaccines. The first, StaphVAX+ will contain both StaphVAX and EpiVAX trade mark in a single vial and the second, CombiVAX, will contain components of StaphVAX, EpiVAX trade mark and EnteroVAX trade mark. The vaccine has completed phase II clinical trials in chronic, ambulatory, peritoneal dialysis patients. Nabi-StaphVAX completed a multicentre, phase III trial in the US involving 1800 end-stage renal disease patients on haemodialysis. In September 2000, Nabi announced preliminary results from the phase III trial; these indicated that although Nabi-StaphVAX elicited a significant decrease in S. aureus bacteraemias in the first 10 months after vaccination, statistical significance was not reached in the primary endpoint of the study, a decrease after 1-year follow up. As a result, the US FDA indicated that US registration would require a second phase III trial in which the primary endpoint is reached. Following discussions with the US FDA, Nabi stated that the initiation of a second phase III trial in collaboration with a corporate partner was likely. Nabi intends to request either an accelerated- or fast-track review by the FDA, on the basis that the vaccine prevents a fatal disease for which no other prophylactics are available. In the meantime, Nabi initiated a boosting study of Nabi-StaphVAX in July 2001. This trial is administering a second dose of Nabi-StaphVAX to 100 patients enrolled in the phase III trial. Nabi plans to begin the confirmatory phase III study of the vaccine, as requested by the US FDA, in 3000 end-stage kidney patients in Q4 2003. The primary endpoint will be a statistically significant reduction of S. aureus bacteraemia caused by type 5 and 8 S. aureus through 8 months post-vaccination, the peak efficacy point in the first phase III trial. This trial will include a booster vaccination at 8 months and vaccinees will be followed up for up to 6 months after the booster to evaluate the vaccine's ability to generate antibodies, efficacy and safety. Results from this study will be used to support eventual product registration, now planned for 2005. In July 2003, Nabi reported that proceeds totalling 32.9 million US dollars from the private placement of its common stock to selected investors will enable the planned confirmatory phase III trial to proceed. In June 2003, Nabi Biopharmaceuticals announced the start of a clinical trial (a bridging study) to evaluate the safety and immunogenicity of a newly manufactured lot of StaphVAX produced by the contract manufacturer, Dow Biopharmaceutical Contract Manufacturing, intended for use in a planned confirmatory phase III trial later in 2003. The study demonstrated that the new batch of vaccine generated antibody levels that were equivalent to the levels generated by the vaccine produced at Nabi's R&D pilot plant and used in previous phase III studies.

Drugs, Investigational↗