Just a quick one.
I see that the current "fear and loathing" being expressed in forums has led to a totally mistaken assumption about a new test for TB that has recently been announced by an American Company.
I'm really not going to waste any time on this other than to point out that this is just another diagnostic for ACTIVE TB. It may or may not be better than the diagnostics for Active TB currently available but it has no direct relevance to us at all - QuantiFERON TB Gold from Cellestis is a diagnostic for LATENT TB.
It's really important to understand the difference. Any level of understanding would preclude the ludicrous suggestion that "maybe this new diagnostic can be modified to detect Latent TB".
Sorry for being so blunt but anybody that is willing to hold a speculative stock for multiple years must be willing to do the necessary work to really understand what they have invested in.
Talking about competition...................
ReplyDeleteHow does TSPOT rate?
I agree that the Xpert MTB/RIF test is not competitive with QFN-TB, but people can be forgiven for thinking otherwise when journalists and analysts write that it is. Also it is worth explaining why it is not competitive and I do so here briefly and basically.
ReplyDeleteIf a person has an infectious disease they have pathogen (ie bacteria or virus) inside them. At the same time, their immune system will be fighting the pathogen using various mechanisms, divided most basically into the innate and adaptive responses. Adaptive responses are acquired during one’s lifetime and are highly specific for the various pathogens. They may be antibody and/or cell-mediated - the relative role of each varies between diseases.
The new Xpert test is designed to diagnose active TB by detecting the TB pathogen in a person (it does this by demonstrating the presence of TB bacterial DNA in a person’s sputum). QFN-TB, on the other hand, examines a person’s cell-mediated immune response to see if they have encountered the TB bacteria. It can be useful in both active and latent stages of the disease.
During latent TB, a patient does not have the bacteria in their sputum and therefore the Xpert method is unlikely to be informative (the NEJM study did not examine latent TB, but this conclusion is reasonable). The Xpert method cannot be performed on another sample type, such as blood, because the TB bacterium is not present in the blood of an infected individual. Without going into a long explanation, I can’t see how this DNA-based (ie molecular) method is likely to be useful for latent TB, certainly in the foreseeable future. Basically, it is a refined version of existing DNA tests for TB and other diseases, which though very useful, have limited applicability in certain infectious diseases - they are only reliable when performed on a certain sample type, are susceptible to contamination and rely on relatively sophisticated reagents and analysers. The NEJM article acknowledges various limitations of the Xpert method.
Even though QFN-TB is an indirect method of ‘diagnosis’ (the definition of diagnosis seems to vary, especially when TB is concerned. Some might say that if you have latent TB you can’t be diagnosed because you don’t have the full-blown disease and perhaps this is why misinformation regarding diagnostic TB methods is rife), it is still very useful. The diagnosis of many diseases relies on examination of a person’s acquired immunity to a large extent (eg, in HIV and hepatitis). In most cases, however, antibody-based immunity is examined, not least because cell-mediated immunity has been difficult to measure in the past. This is why the QFN technology is significant – it offers a way of measuring cell-mediated immunity and theoretically is applicable to a range of diseases, infectious and otherwise. The closest technology to it is ELISpot and it is much less easy to perform.
It is hard to see how the Xpert method will render the QFN-TB method redundant because of the need for latent TB testing. It is better to detect and treat infected individuals before they have TB bacteria in their sputum in order to halt the spread of disease (during latent TB the bacteria lurks in calcified regions of the lung). Also, one should not rule out the possibility that CST is working on a version of QFT-TB for the developing world that would coexist with the Xpert method. The Xpert method is the result of a public/private/charity collaboration and unlikely to be competitive in a cut-throat way.
I used to work for a biotech company that received much mainstream press coverage and it always was inaccurate, sometimes grossly so. Certainly, the New Yorker article on TB contains multiple inaccurate details.
BTW, please don’t base your financial decisions on anything I have written. I expect the topic of competition will come up at the AGM.
Lab rat
Glad to see rational thinking is alive and well,your comments re active and latent (us old hands now are well versed in the distinction)sorted out possible fears of genuine competition and failing to return a call is not a crime but a "senior moment".
ReplyDeleteI hope you enjoyed La Belle France.
regards