Cepheid's 'Revolutionary' Test Identifies TB Within Two Hours
Technology that protects U.S. postal workers from anthrax also cuts the time to diagnose tuberculosis to minutes from days, giving doctors a new tool to snag an ancient killer resurging globally.
Cepheid Inc.’s GeneXpert device correctly detected the bacterium within 90 minutes in about 98 percent of people with an active form of the lung disease, including a strain that evades the strongest antibiotic used to treat most patients, according to a study in the New England Journal of Medicine.
The most widely used tuberculosis test is 125 years old and routinely misses half of all cases, doctors said in an editorial accompanying the study. The World Health Organization is reviewing the Bill and Melinda Gates Foundation-funded study to decide whether to recommend the device in control programs, said Mario Raviglione, director of the agency’s Stop TB department.
“This new test is clearly revolutionary,” Raviglione said in an Aug. 31 telephone interview from Geneva. “We are really in a situation of changing practice in the way tuberculosis has been dealt with over the last century and a half.”
The need to find and treat sufferers has become more urgent as new drug-resistant forms transform an infectious disease that could be treated with $20 worth of medication into an unstoppable scourge. Unless the disease is suppressed by a cocktail of antibiotics, a patient will typically infect 10 to 15 others in a year, according to the Geneva-based WHO.
Almost half of multidrug-resistant TB cases worldwide occur in China and India, WHO estimates. Most laboratories in developing countries diagnose TB by looking for the bacterium in phlegm under a microscope.
Grown in Dishes
Patients aren’t routinely tested for drug-resistant strains unless an initial course of antibiotics fails. That analysis may take weeks while laboratory technicians grow the germs in dishes before seeing whether they’re killed by various medications.
The device made by Sunnyvale, California-based Cepheid searches for genes that enable the bacteria to resist rifampin, the strongest in a four-drug cocktail given to newly diagnosed patients. A positive result would enable doctors to immediately prescribe alternatives such as Bayer AG’s Avelox, potentially cutting treatment time and the risk of further spread.
More than a quarter of people diagnosed with TB in one region of northwestern Russia in 2008 had a form of the disease not treatable with rifampin and another generic antibiotic called isoniazid, the WHO said in March. Medicines to cure a person’s multidrug-resistant TB may cost as much as $5,000, while treatment for extensively drug-resistant TB, which doesn’t respond to even stronger antibiotics, is far more expensive.
There were 9.4 million new TB cases and 1.8 million TB deaths in 2008, WHO estimates. Multidrug-resistant TB probably infected 440,000 people, killing 150,000, WHO said in March.
“A lot of people die of their TB before they can go on to have this kind of drug testing and have better drugs given to them,” Justin Denholm, an infectious diseases specialist at the Royal Melbourne Hospital in Australia who wasn’t involved in the study, said in a telephone interview.
A scientific panel convened by the WHO is scheduled to meet in Geneva today to assess the data from this and other studies, said Karin Weyer, who coordinates efforts to improve diagnostic and laboratory techniques for the Stop TB program. A decision whether to recommend the GeneXpert to WHO’s 193 member-states may be made by the end of the month, she said on Aug. 31.
“If we have the evidence by the end of the month that this is as exciting as it looks, then it has a huge public health benefit,” Weyer said in a telephone interview.
The basic version of the GeneXpert, which is the size of a desktop computer processor, costs about $30,000 in the U.S. and will be offered public health-care providers in developing countries for about $10,000, Cepheid Chief Executive Officer John Bishop said in a telephone interview. Samples from each patient are collected in a single-use cartridge for processing inside the device.
Cepheid has been supplying a variant of the GeneXpert to the U.S. Postal Service to test for anthrax spores in packages. It also markets a range of testing kits for hospital-acquired infections like MRSA.
The 14-year-old company, whose shares have advanced 26 percent this year, is developing tests for lung cancer and sexually transmitted diseases. Cepheid rose $1.06, or 7.2 percent, to $15.77 at 4 p.m. in Nasdaq Stock Market composite trading yesterday.
India, South Africa
The TB test was jointly developed by the Foundation for Innovative New Diagnostics, a Geneva-based nonprofit group that targets neglected diseases. Samples from more than 1,400 patients from India, South Africa, Peru and Azerbaijan were tested and results were compared with currently used diagnostic techniques, according to the study published yesterday.
If GeneXpert is recommended by the WHO for use in tuberculosis surveillance and monitoring, demand for the single- use cartridges may be in the range of “hundreds of thousands very soon and in the millions in the next one or two years,” said Giorgio Roscigno, chief executive officer of FIND, in a telephone interview.
Cepheid plans to sell the cartridges in developing countries for 25 euros ($32), half of what it charges in Europe. “As test volumes go up, we will further reduce the price point that will be available for the developing countries,” Bishop said.