David Edwards, a biomedical engineering professor at Harvard University, thinks he may have a better vaccine against tuberculosis in the works. He’s negotiating with the Bill & Melinda Gates Foundation and other international nonprofits to pump enough cash into a clinical trial to get an early glimpse into whether he’s really onto something.
Edwards, through an international nonprofit he established called Medicine in Need, or MEND, is preparing to move the first inhalable TB vaccine candidate into clinical trials within the next six months, he says. Unlike other vaccines in development that are liquid injectables, this one comes in a dry powder form that should be easy to ship and store in all sorts of weather conditions. That also helps it avoid the problems associated with dirty needle injections, Edwards says. Plus, since it’s an adapted form of an 80-year-old TB vaccine that’s given to hundreds of millions of infants every year, its raw material is available for pennies a dose, and might be able to advance through clinical trials faster than other candidates that might need more testing, Edwards says.
“We’ve got a big problem, since one-third of the world has TB, and the current TB vaccine doesn’t work as well as we need,” Edwards says. “This is a big goal.”
Tuberculosis is one of the top killers in the world today, causing about 1.5 million deaths a year, or 5,000 people a day, mostly in developing countries. It’s a bacterial infection of the lungs, often found in patients with HIV whose immune systems have been weakened.
Edwards brings serious expertise to the task of a new TB vaccine, having been a former student of MIT’s pioneering biomedical engineer, Robert Langer. Those two are still close collaborators, and they spend a fair amount of time thinking about the lungs. Langer and Edwards caught our attention last month with a company they co-founded, called Pulmatrix, which said it believes it has discovered a way to alter the mucus lining of the lungs to prevent any number of viral and bacterial infections from making people seriously ill, and to prevent patients from spreading the bugs around. Langer said he’s also impressed with Edwards’s other project, the inhalable TB vaccine.
“It would be great for the Third World,” Langer says in an e-mail. “No needles, and no need for trained personnel. Plus the vaccine would be dry powder. It’s much better for warm climates, and it would be stable.”
The new approach against TB aims to improve upon a vaccine that’s been widely used for 80 years, Edwards says. The injectable vaccine, called BCG, is a live-weakened form of the bacterial invader that trains the immune system to fight off infection when it runs into the bug. One problem is that it wears off after about 10 years, so infants who get it in the developing world lose protection as they get older, he says. The vaccine doesn’t work as well in adults, either.
Edwards’s idea got kickstarted in 2004 when it received its first grant from the Gates Foundation, for about $8 million. MEND now has about 20 employees, with offices in Cambridge, MA, Pretoria, South Africa, and Paris, France.
The work got started with an effort to come up with a needle-free vaccine that might be more practical for newborns, Edwards says. Then a surprising thing happened in tests of guinea pigs. Animals that were vaccinated with the injectable TB vaccine, and then exposed to large amounts of the bacteria, ended up getting a lot less of the pathogen in their lungs and throughout their bodies than those that weren’t vaccinated. But a third group of guinea pigs that got the inhalable vaccine had even less of the pathogen in their lungs and other tissues than those that got the injectable version, Edwards says. It’s hard to say for sure why, he says.
Of course, it’s just an animal study, and critics can point out plenty of reasons why it might not translate in the real world. The study didn’t look at whether the guinea pigs on inhalable vaccine remained healthy; they were given unusually high exposures to TB bacteria; and it didn’t measure how long the vaccine would last. That’s a key question, because in real life, public health officials want to see a vaccine that lasts at least 30 years, Edwards says. Of course, that can make for a very difficult clinical trial, so that’s all part of the negotiations with health authorities. It’s safe to say we all hope we don’t have to wait 30 years for a definite answer on whether a new TB vaccine really works.
