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Use of recombinant human antithrombin in patients with congenital antithrombin deficiency undergoing surgical procedures.

BACKGROUND: Hereditary antithrombin (AT) deficiency is associated with a significant risk of venous thromboembolism. Patients with this disorder frequently require long-term anticoagulation. Discontinuation of anticoagulation for childbirth or surgery may carry a substantial thrombotic risk. For this reason, replacement with AT concentrate has been used when anticoagulation is interrupted. A new recombinant human AT concentrate, produced using transgenic technology, has recently been developed. STUDY DESIGN AND METHODS: Human recombinant AT (rhAT) was provided by GTC Biotherapeutics, Inc. on a compassionate-use basis for five patients with hereditary AT deficiency who underwent six surgical procedures. Patients were treated perioperatively. Dosing was determined individually by the investigators with a goal of maintaining an AT activity of 80 to 150 percent. RESULTS: There was no clinical evidence of thrombosis or bleeding. Four of the five patients had postoperative duplex ultrasound studies of the lower extremities, which showed no evidence of acute thrombosis. Four patients were tested for antirecombinant rhAT antibodies postoperatively and were negative. CONCLUSION: These case reports indicate that rhAT can provide effective support for AT-deficient patients who undergo surgery. Further study of this product is needed to define optimal dosing and further assess clinical response.

Adult↗

Characterisation of an industrial affinity process used in the manufacturing of digoxin-specific polyclonal Fab fragments.

This paper describes the effect of several variables on the affinity process for the production of the FDA approved biotherapeutic product Digoxin Immune Fab (Ovine) (DigiFab, Protherics Inc., TN, USA). The study considers the effects of column re-use on matrix capacity and on the subsequent recovery of the antibody product, and the impact of varying column loading on matrix performance. The methodology used could be equally applied to assess the feasibility of using an affinity matrix for commercial scale purification of alternative antibody derived biotherapeutics. The capacity and specific Fab recovery were calculated through 24h equilibrium and mass balance studies. Results were assessed against data obtained through confocal scanning laser microscopy. Scale-down experiments produced specific Fab recoveries and purities that were comparable with those at production scale. The matrix capacity was found to be 45+/-15 mg of Fab/ml of matrix. Through the use of fluorescent DigiFab and confocal scanning techniques, Fab uptake onto single affinity bead was evaluated. Average intensity values calculated for each sample provided direct real-time, measure of Fab binding and matrix capacity. The results suggest that the affinity matrix had a limited reuse life as a drop in recovery is observed following the completion of a small number of process cycles (30% after three runs). The findings support that which is seen at the current manufacturing scale, where the affinity column is used for a limited number of runs. Results from this study can be used as a basis for future optimisation of this purification process.

Animals↗

Virulizin.

Virulizin, a biological response modifier, is a mixture of proteins and peptides that have been extracted from bovine reticuloendothelial tissue that activates macrophages. It is being developed by Lorus Therapeutics (formerly Imutec Pharma) for the treatment of various cancers and had completed phase II clinical trials in Canada for the treatment of pancreatic cancer and advanced malignant melanoma. The commencement of phase III clinical trials in Canada, for the treatment of pancreatic cancer, was delayed due to quality control problems with batches of virulizin and all clinical trials of virulizin were suspended as Lorus underwent a major restructuring programme. However, phase I/II clinical trials are now underway again in Canada in HIV-positive patients with Kaposi's sarcoma and for the treatment of pancreatic cancer. A phase I/II clinical trial is also underway in patients with pancreatic cancer in the USA. Lorus announced in June 2000 that it had completed a meta analysis of three phase I/II studies of virulizin that showed the drug increased survival and improved quality of life for pancreatic cancer patients. Based on these positive results, Lorus initiated a phase III trial to be conducted at 40 sites in North America in November 2001. The study aims to enrol 350 patients with advanced pancreatic cancer and will test the effectiveness of virulizin as first- and second-line treatment of pancreatic cancer. The study will compare virulizin + gemcitabine with gemcitabine alone as first-line therapy, while second-line treatment will involve patients who have failed to respond to gemcitabine. Some of these patients will receive virulizin + fluorouracil while another group will receive only fluorouracil. The study is scheduled to complete in 2004 or early 2005. Virulizin received orphan drug status for this indication from the US FDA in February 2001. Lorus received fast track designation from the FDA in June 2002 for virulizin for the treatment of pancreatic cancer. Virulizin is registered for the treatment of malignant melanoma in Mexico and is due to be launched there in 2002. Lorus has entered into an exclusive 7-year distribution agreement with Faulding Canada Inc., giving Faulding (now part of Mayne Group) the right to market and sell virulizin in Mexico for the treatment of melanoma. Lorus will receive royalties from sales of the product and will be responsible for its manufacture. In April 2002, Mayne exercised its option to acquire the distribution rights for virulizin in Brazil. Lorus Therapeutics has signed a collaborative agreement with NaPro BioTherapeutics, USA, to study the efficacy of virulizin in combination with paclitaxel for the treatment of lung adenocarcinoma. Lorus is conducting preclinical studies of virulizin in human breast cancer, lung, ovarian and prostate cancer, and has reported successful activity of the agent in these indications. Lorus was awarded a patent by the US Patent and Trademark Office to protect the only known process used to create virulizin. This patent, in conjunction with the patents issued in Australia, South Africa, New Zealand, Korea and Singapore, broadens and strengthens the protection of Lorus' intellectual property rights regarding the process, composition and use of virulizin.

Adjuvants, Immunologic↗

Natalizumab: AN 100226, anti-4alpha integrin monoclonal antibody.

Natalizumab [AN 100226, anti-alpha4 integrin monoclonal antibody, Antegren] is a humanised monoclonal antibody that blocks alpha4beta1 integrin-mediated leukocyte migration. Natalizumab is in phase III trials for the treatment of multiple sclerosis in North America and the UK, and for the treatment of Crohn's disease also in the UK. It may have potential in the treatment of other immune-related inflammatory disease. Elan Corporation intends to examine the potential of natalizumab in rheumatoid arthritis and ulcerative colitis. 4beta1 integrin on circulating leukocytes binds to vascular cell adhesion molecule-1, which is expressed at high levels in the blood vessels in the CNS during exacerbations of multiple sclerosis. This allows leukocytes expressing alpha4beta1 integrin (very late antigen-4) to move from the peripheral blood into the CNS. Inflammatory proteins and other factors released from lymphocytes in the brain lead to the progression of symptoms. A limitation of natalizumab is that it must be injected and cannot be administered orally. Scientists have transformed the large anti-alpha4 monoclonal antibody into much smaller, drug-like molecules suitable for oral administration. Protein Design Labs has granted a worldwide nonexclusive licence under its antibody humanisation patents to Elan Pharmaceuticals for natalizumab. Biogen Inc. has entered into an agreement with Elan for a worldwide exclusive collaboration to develop, manufacture and commercialise natalizumab for multiple sclerosis and Crohn's disease and rheumatoid arthritis. Development of natalizumab is also being funded, in part, by Axogen (acquired by Elan in 1999). In November 2003, Biogen and IDEC Pharmaceuticals merged to form Biogen Idec. Elan repurchased royalty rights on a package of products, including natalizumab, from Autoimmune Disease Research Company. Elan and Genzyme Transgenics Corporation signed an agreement to produce natalizumab in GTC's genetically engineered goats, which will express the compound in their milk. Genzyme Transgenics Corporation changed its name to GTC Biotherapeutics in June 2002; it is no longer a subsidiary of Genzyme Corporation. Following discussions with the US FDA, Elan completed enrolment in a second phase III trial, involving approximately 420 patients with Crohn's disease. This Evaluation of Natalizumab as Continuous Therapy-2 (ENACT-2) trial evaluated the effect of natalizumab on duration of response and remission in patients with Crohn's disease. In January 2004, Elan Corporation and Biogen Idec announced that the phase III, ENACT-2 maintenance trial of natalizumab in Crohn's disease met the primary endpoint of maintenance of response. Elan and Biogen Idec will discuss these data with regulatory authorities in both the US and Europe and determine the appropriate path forward for natalizumab in Crohn's disease. An NDA for Antegren in Crohn's disease was expected to be filed at the end of 2003; however, due to failing to meet the primary endpoint in the induction trial, Elan is unable to predict when and if a regulatory filing will be made. Earlier, on 23 January 2001, the Wall Street Journal reported that the Biogen CEO expects Antegren to become a blockbuster drug, with sales of at least $US1 billion. He also predicted that Antegren could be on the market as early as 2003 for the indication of Crohn's disease and in 2004 for multiple sclerosis. The Journal stated that Biogen is under pressure to develop new drugs since its flagship product Avonex will be losing its US Orphan Drug Act protection in 2003. Antegren has a different mechanism to that of Avonex and could be used either alone or as a combination therapy.

Animals↗