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Oxford, UK; 02 August 2006 – Oxford Immunotec Ltd, the T cell measurement company, has today announced the outcome of two studies comparing its T-SPOT.TB assay with other diagnostic tests for latent tuberculosis (‘TB’) infection. The results of both studies demonstrated that T-SPOT.TB is significantly more sensitive than other diagnostic tests for tuberculosis, far less affected by immunosuppression and is able to provide an accurate result each time a test is carried out. The first study, published in the Lancet, was conducted in Modena, Italy by Giovanni Ferrara and colleagues. This study compared the performance of the three main assays for detection of TB infection, the traditional Tuberculin Skin Test (‘TST’) and two blood assays, T-SPOT.TB and QuantiFERON-TB Gold (‘QFT’) (Cellestis: Australia) in routine clinical practice1. The study was conducted in 383 patients enrolled on suspicion of active or latent TB disease. The key findings of the study were that T-SPOT.TB identified more TB positive individuals (38%) than QFT (26%). This difference was statistically significant. In their analysis of the results the authors confirmed their belief that the higher number of positive results identified was explained by the higher sensitivity of T-SPOT.TB. In a sub-cohort of 24 patients with a diagnosis of active disease, 83% (20 patients) were positive by T-SPOT.TB, 74% were positive by QFT (17 patients) with one indeterminate result and 70% were positive by TST (14 patients). Indeterminate results were also reported both for the study as a whole and also for a variety of higher risk sub-groups within the study. An indeterminate result occurs when a test is completed but the result cannot be interpreted. This may be caused by a lack of sensitivity in the assay or by the patient having too few T cells to elicit a response. Reported indeterminate rates are given below:
The overall difference in indeterminate rates was statistically significant and shows that the QFT assay was unable to produce results in a substantial number of immunosuppressed groups, as well as patients of very old and young age. In contrast, T-SPOT.TB gave evaluable results in 97% of subjects and was only significantly affected by the severe immunosuppression associated with cancer chemotherapy. The findings from the Ferrara study are supported by another study completed at the Asan Medical Centre, Seoul, South Korea by a group led by JY Lee. This study was published in the April edition of the European Respiratory Journal and compared the performance of T-SPOT.TB, TST and QFT in a group of patients with a high clinical suspicion of active TB2. The results from this group were compared against a low risk control group of healthy patients. The overall sensitivity of T-SPOT.TB in the 87 patients diagnosed with active TB disease was 95.4%. This was significantly higher than the results achieved with QFT (70.1%) and TST (66.7%). Moreover 8 patients gave indeterminate results using QFT, while no indeterminates were observed with T-SPOT.TB. In a sub group of these active TB disease patients (n=29) who also had concomitant immunosuppression, the sensitivity of T-SPOT.TB was unaffected whereas the sensitivity of both QFT and TST fell. Commenting on the reported findings, Peter Wrighton-Smith, Chief Executive Officer of Oxford Immunotec said “These studies represent the first significant effort to directly compare the performance of T-SPOT.TB and QFT. It is clear from the results presented in these two papers that T-SPOT.TB is significantly more sensitive than its competitors, far less affected by immunosuppression and is able to provide an accurate result each time a test is carried out with very few indeterminates. We expect the clinical case for T-SPOT.TB to be further strengthened, with a significant number of further studies directly comparing the performance of each of the tests due to be published in the coming months”. - ENDS - Notes to editors: About Oxford Immunotec Oxford Immunotec, the T cell measurement company, is headquartered near Oxford, UK. The Company develops and sells clinical diagnostic products based on its patented T-SPOT® technology, the first regulatory approved method for directly quantifying antigen-specific T cells. T-SPOT is a simple and extremely accurate method of studying a person’s cellular immune response to infection and can be applied to diagnose and monitor any major disease driven by a T cell response. About T-SPOT®.TB T-SPOT.TB is an in vitro T cell measurement assay used for diagnosing TB disease and latent TB infection and the first product from Oxford Immunotec using the T-SPOT technology. The product is extremely robust in that it gives a result every time and offers unrivalled and maintained sensitivity in high risk and immunocompromised patient groups. T-SPOT.TB is approved for sale in Europe and is designed to replace the 115 year old Tuberculin Skin Test. As such it offers a substantially more accurate and effective tool for controlling the spread of TB, addressing a market of £600m. Unlike the traditional Tuberculin Skin Test, the T-SPOT.TB test incorporates a positive control, allowing the user to distinguish between a genuine negative result and one which is indeterminate (i.e. an inconclusive result) as a result of a technical failure. T-SPOT is a trademark of Oxford Immunotec. References 1 Use in routine clinical practice of two commercial blood tests for diagnosis of infection with mycobacterium tuberculosis: a prospective study – Ferrara et al: Lancet 2006; 1,328-34 2 Comparison of two commercial interferon gamma assays for diagnosing mycobacterium tuberculosis infection – Lee et al: ERJ Express 12 April 2006 For more information please contact: At Oxford Immunotec:
Dr Peter Wrighton-Smith,
CEO Oxford Immunotec 91 Milton Park Abingdon Oxfordshire OX14 4RY, UK Tel: +44 (0)1235 442780 Fax: +44 (0)1235 442781 Email: info@oxfordimmunotec.com At Northbank Communications: (for Oxford Immunotec) Lorna Watson, Senior Account Manager
Northbank
Communications Ltd
Tel: +44 (0)20
7886 8157
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