Monoclonal antibodies clinical trials

Adalimumab (Humira ) is a folly human anti-TNF monoclonal antibody that is mainly used in combination with methotrexate to treat rheumatoid arthritis in adults [3]. Meanwhile, it is also used against arthritis of psoriasis and ankylosing spondylitis. Its therapeutic value in Crohn s disease is under clinical trial. 

Clinical trials have indicated that omalizumab, a recombinant humanized monoclonal IgE antibody approved for use in moderate to severe persistent asthma in patients with reactivity to a perennial allergen, is effective in the treatment of SAR.25-27 Omalizumab inhibits the binding of IgE to mast cell and basophil receptors, resulting in a reduction of allergic mediator release.25 Additionally, serum free IgE levels are decreased.2 27 In SAR patients, omalizumab improves quality of life and nasal symptoms and reduces antihistamine needs. The most effective dose in SAR appears to be omalizumab 300 mg administered subcutaneously every 3 to 4 weeks depending on baseline IgE levels.26,27... 

Monoclonal Antibodies. HA-1 A is a human monoclonal IgM antibody that binds to LPS and lipid A. The initial phase 3 trial demonstrated no overall benifit of HA-1 A compared with placebo (Z5). However, HA-1A appeared to afford significant protection to a subgroup of patients with gram-negative bacteremia (Z5). A second large-scale trial documented a lack of overall clinical benefit of HA-1A (W11). 

The safety of the cocaine vaccine TC-CD in former cocaine abusers has been evaluated in a Phase I clinical trial, and it was determined that the vaccine was well tolerated with dose-related increases in antibody levels.65 Two Phase II clinical trials have now been conducted.66,67 The vaccine was again well tolerated and subjects reported a reduction in cocaine s reinforcing effects. The antibody levels were detectable after the second dose, peaked at 8 to 12 weeks, and remained elevated for up to 6 months preliminary findings indicated a negative association between antibody level and cocaine use. Other anti-cocaine vaccines in development include a blocking antibody (ITAC-cocaine) and a monoclonal catalytic antibody (15A10). 

The most widely studied therapeutic proteins produced in plants include monoclonal antibodies for passive immunotherapy and antigens for use as oral vaccines [40]. Antibodies against dental caries, rheumatoid arthritis, cholera, E. coli diarrhea, malaria, certain cancers, Norwalk virus, HIV, rhinovirus, influenza, hepatitis B virus and herpes simplex virus have been produced in transgenic plants. However, the anti-Streptococcus mutans secretory antibody for the prevention of dental caries is the only plant-derived antibody currently in Phase II clinical trials [40]. Until recently, most antibodies were expressed in tobacco, potato, alfalfa, soybean, rice and wheat [9], It has been estimated that for every 170 tons of harvested tobacco, 100 tons represents harvested leaves. A single hectare could thus yield 50 kg of secretory IgA [3, 41]. Furthermore, it has been estimated that the cost of antibody production in plants is half that in transgenic animals and 20 times lower than in mammalian cell cul-... 

Thus, the tetravalency, anti-inflammatory properties and molecular stability of slgA make it particularly suitable for protective passive immunity when applied to mucosal surfaces. To date, the clinical evaluation of slgA protection in humans and animal models has been very limited. Indeed most studies have employed monomeric IgA monoclonal antibodies [3,15]. Hence, differences in IgA and IgG protective activities at the mucosal level have often not been observed [15]. Only a few studies have demonstrated the superior activity of polymeric IgA or slgA compared with monomeric IgG or IgA [16]. In order to determine the efficacy of slgA, future animal experiments and clinical trials are needed to compare the activities of IgG monoclonal antibodies and their slgA counterparts. The ability to engineer slgAs in plants will allow these comparisons to be made [17]. 

At least 1000 potential biopharmaceuticals are currently being evaluated in clinical trials, although the majority of these are in early stage trials. Vaccines and monoclonal antibody-based products represent the two biggest product categories. Regulatory factors (e.g. hormones and... 

Despite the scientific elegance of the antibody-mediated approach to tumour detection/destruc-tion, initial clinical trials proved disappointing. A number of factors contributed to their poor therapeutic performance, particularly against solid tumours. Most such factors relate directly/ indirectly to the fact that the first generation of such drugs utilized whole monoclonal antibody preparations of murine origin. These factors include ... 

Priliximab (cM-T412) is an anti-CD4 chimeric monoclonal antibody that was evaluated in the clinic for the treatment of autoimmune diseases. Priliximab binds to CD4 on the surface of T cells and leads to a profound and sustained decrease in circulating CD4+ T cells decreased counts have been reported to be below normal levels at 18 and 30 months following single- and multiple-infusions.81 Similar findings were observed in preclinical studies in chimpanzees.82 The administration of priliximab was also associated with a cytokine-release syndrome that caused transient fever, myalgia, chills, headache, nausea, and/or hypotension that was accompanied by an increase in serum IL-6. Although evidence of efficacy was observed in clinical trials for CD, the... 

BioPortfolio. IDEC (NASDAQ IDPH) has halted clinical trials of its therapeutic monoclonal antibody IDEC-131 [online]. Available at http //www.bioportfolio.com/news/ btech 061102 l.htm [Accessed 2006]... 

Clinically, monoclonal antibodies are also proposed as drug delivery vehicles in certain tumors where specific tumor-associated antigens are expressed. In this context, investigators have found that by conjugating toxins such as the A chain polypeptide of the plant protein ricin or the bacterial toxin from Corynebacterium diphtheriae to monoclonal antibodies specific for certain tumor type, as few as one or two molecules of antibody-toxin conjugate can destroy a tumor cell in vitro. Some success has also been obtained in clinical trials with monoclonal antibody-toxin conjugates. 

Preclinical studies should address the potential toxicity due to inappropriate release of the conjugated toxin. Preclinical toxicology of monoclonal antibodies may not require extensive animal studies but should be examined for cross-reactivity with antigenic epitopes present on normal cells in vitro and for the presence of human or rodent vimses. Early clinical trial should involve biodistribution studies with radiolabelled material. 

Another creative trial design was performed for the pivotal trial for approval of the monoclonal antibody cetuzimab (Erbitux). The clinical trial was based on the preclinical evidence. Erbitux was synergistic in animal model systems. 

The development and commercial success of the first monoclonal antibody used to treat tumors in the United States have had broad consequences. Companies have pushed ahead with the development of a variety of additional monoclonal antibodies. Six years after rituximab was approved, more than one third of the 38 approved recombinant proteins manufactured in mammalian cells were antibodies (some of the most notable are listed in Table 32.1). Many of these antibodies are used at large doses that were not thought to be economically practical 10 years ago. Today, the pharmaceutical industry is facing a projected shortage of manufacturing plants for recombinant proteins synthesized by mammalian cells, and there are still more than 400 monoclonal antibodies reported to be in clinical trials. 

Van Oers, M.H., Hagenbeek, A., Van Glabbeke, M., and Teodorovic, L, Chimeric anti-CD20 monoclonal antibody (Mabthera) in remission induction and maintenance treatment of relapsed follicular non-Hodgkin s lymphoma a phase III randomized clinical trial — Intergroup Collaborative Study, Ann. HematoL, 81, 553-557, 2002. 

The annual R D expenditure for biopharmaceuticals is around US 19-20 billion. There are estimated to be 2500 biopharmaceuticals in the discovery phase, 900 in preclinical trials, and 1600 in clinical trials. This represents 44% of all drugs in the development phase and 27% of all drugs in both preclinical and clinical trials. The most common target is cancer and monoclonal antibodies and vaccines have the largest amount of R D activities. 

Tumor Necrosis Factor There are two types of tumor necrosis factor TNF-a and TNF- 8. Of the two, TNF-a has been studied in more detail. TNF-a is a 157 amino acid polypeptide. It is a mediator of immune regulation, including the activation of macrophages and induction of the proliferation of T cells. Another TNF-a function is its cytotoxic effects on a number of tumor cells. Recent research, however, concentrates on its property in the stimulation of inflammation, particularly in the case of rheumatoid arthritis. Clinical trials are being conducted with drugs to block TNF-a with anti-TNF-a monoclonal antibodies. These antibodies target the excessive levels of TNF-a in the synovial fluid of joints and provide relief to sufferers of rheumatoid arthritis (Exhibit 4.10). 

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