One of the major impediments to creating drugs for diseases of the developing world has always been the lack of money to cover the high costs of drug development. The $104 million grant from the Bill and Melinda Gates Foundation to the Global Alliance for TB Drug Development aims to address that issue directly. While the alliance’s work on tuberculosis drugs won’t put much money in the pockets of drug companies, its success would provide other benefits to industry.
The funding allows the alliance to pursue innovative scientific, regulatory and business strategies that could be valuable to industry. Even more, it provides an opportunity to recoup the industry’s reputation in developed and developing countries.
Although the developed world market for TB therapies is small, the alliance is applying a technology transfer model that could be applicable to other diseases that afflict wealthy and poor countries: the nonprofit assumes much of the cost and risk of getting new drugs to market, and industry retains rights in developed nations.
The TB Alliance’s efforts to identify and validate biomarkers also could serve as proof of concept for developers of antiinfective therapies, as could its attempt to create scientific and regulatory support for accelerating the development of combination therapies.
Pharmaceutical and profitable biotech companies also have a political incentive for partnering with the alliance and similar nonprofit ventures focused on diseases that trouble primarily poor countries: Some of the biggest public policy risks for industry are price controls and attenuation of IP rights in the U.S. and Europe.
Other benefits from collaboration include gaining experience with clinical trials in developing countries and maintaining scientific expertise in infectious disease research.
Indeed, TB poses several difficult challenges. Globally, it is a massive public health problem — the disease kills about 2 million people every year — but it occurs principally in countries that are too poor to pay for therapy. Standard therapy typically requires 130 doses of drugs taken over six months, while multidrug resistant TB can take up to two years to treat.
The TB Alliance seeks to cut the treatment time in half over the next five years and in the long term to develop therapies that eliminate the infection in a matter of days.
A model partner
To do so, the alliance has adopted several partnership models, including co-investing in and co-developing compounds, and in-licensing technology.
In general, it is inverting the conventional wisdom about public-private drug development. Rather than rely on government-financed academics to discover drug candidates that are then tested by pharmaceutical companies, a key part of the alliance’s strategy is to tap into industry’s strength in discovery and to mitigate its exposure to the riskiest part of drug development – clinical trials.
The new Gates Foundation grant, announced in late May, will pay for Phase III trials of the alliance’s most advanced compound, moxifloxacin, and for preclinical work on nine compounds in the alliance’s portfolio
Bayer AG (FSE:BAY; BAY, Leverkusen, Germany) is partnering to develop moxifloxacin, a quinolone antibiotic that is widely used worldwide to treat bacterial respiratory and skin infections. The company is providing the drug free for clinical trials coordinated by the alliance and has agreed to provide it to patients in the developing world on an affordable basis if it is approved for TB.
BAY also is contributing critical knowledge to the endeavor, TB Alliance President and CEO Maria Freire told BioCentury. “Bayer provides drug, and that is some savings, but it is also contributing its experience with 400 million doses, and that is substantial,” she said. “If I had to go back and learn all the lessons Bayer has learned for moxifloxacin, that would cost us a tremendous amount of time and money.”
The trials involve substituting moxifloxacin for either ethambutol or isoniazid, two of the four standard TB drugs. Preclinical data suggest that moxifloxacin will cut the time required to treat TB by two months. Freire expects it to receive FDA approval by the first quarter of 2011.
The alliance’s next most advanced compound is PA-824, a nitroimidazole in-licensed in 2002 from Chiron Corp., now a subsidiary of Novartis AG. PA-824 has shown bactericidal activity against multidrug-resistant tuberculosis.
The Novartis Institute for Tropical Diseases in Singapore is designing, synthesizing and optimizing a series of new analogs of PA-824, and the alliance is contributing chemical intermediates and scientific expertise, including structure design, and support for pharmacological studies.
The alliance, which is responsible for clinical testing of PA-824, has completed a Phase I study.
Novartis (NVS; SWX:NOVN, Basel, Switzerland) has agreed to make compounds developed with the alliance available without profit in developing countries where TB is endemic. It has grant-back rights for certain developed country markets.
NVS also has the rights to manufacture drugs that are developed by the partnership, “with the proviso that if we can find a cheaper manufacturer that would reduce the price, Chiron would have to meet that price or allow us to manufacture elsewhere,” Freire said.
The TB Alliance is also collaborating with industry on early stage discovery.
In March 2005, Freire and Tadataka Yamada, then chairman of R&D and executive director at GlaxoSmithKline plc (LSE:GSK;GSK, London, U.K.), announced a collaboration consisting of four programs aimed at discovering TB therapies with novel mechanisms of action.
On June 1, Yamada became executive director of global health at the Gates Foundation.
GSK, which has a long history of developing therapies for tropical and developing world diseases, is looking for anti-TB activity in three classes of compounds: pleuromutilin antibiotics, isocitrate lyase inhibitors, and inhibitors of InhA, an enoyl-ACP reductase enzyme involved in the synthesis of fatty acids in TB. The company also is screening its antimicrobial library for compounds that are active against relevant molecular targets.
The alliance pays half of the cost for the personnel working on the project.
Abbott Laboratories (ABT, Abbott Park, Ill.) has granted the alliance rights to the company’s patents on quinolone antibiotics. TB Alliance-funded researchers at the Korean Research Institute of Chemical Technology and Yonsei University in Seoul have identified a subclass of quinolones with potent activity against TB and are working on lead optimization.
In addition to the lack of commercial markets for TB drugs, development of new therapies is stymied by an unusual legacy.
The four drugs used to treat TB — isoniazid, rifampin, ethambutol and pyrazinamide— were approved between 1952 and 1963 and have never undergone modern clinical testing. Today, regulators usually require studies of each component of a combination to characterize its efficacy and safety, and then of the combination.
The individual contributions of the drugs used to treat TB are not known, and it isn’t even clear that two of them, isoniazid and ethambutol, are necessary, according to Mel Spigelman, director of R&D at the alliance. There are some data showing that patients who are resistant to isoniazid respond to the four-drug combination, he noted.
“We are starting with a situation in which there are no good data about the individual components of the combination or how much efficacy, if any, would be lost if we take one or two out,” Spigelman told BioCentury. “We can’t ethically do the studies to test this. TB is a curable disease so we can’t do a decent length trial to even test what a single drug would do because we can’t lose the chance for a cure.”
The alliance is convinced a combination of drugs is necessary because the organism is capable of rapidly evolving resistance to a single agent. But one of its goals is to simplify the regimen.
Spigelman estimated it would take at least 24 years to test and obtain approvals for a replacement for the existing TB regimen using the conventional approach in which each drug is developed individually.
Moreover, the alliance is casting a wide net for candidates — and is not excluding either components of the current therapy or drugs that other entities are developing.
The alliance plans to test all of its candidates individually in Phase I trials and to conduct extensive preclinical evaluation of various combinations in an effort to identify compounds that have complementary activity. “In a sense, we are doing preclinically what should over the years have been done clinically,” Spigelman said.
Only compounds that can be manufactured and marketed to patients in the developing world at affordable prices will be considered, Freire noted.
In an effort to slash the time required to test a new combination to six years, the alliance has launched discussions with FDA and EMEA to develop a strategy that would avoid having to do individual testing of new compounds and take them directly into combo studies. This would allow the alliance to conduct efficacy studies of combinations with compounds that have not been tested individually in TB patients.
Marking the Way
In addition to reducing development times by launching combination studies, the alliance is sponsoring the development of biomarkers that could reduce the uncertainty and perhaps the time required to conduct trials. It announced a biomarker collaboration with BG Medicine Inc. (Waltham, Mass.) in February (see BioCentury, Feb. 27).
“The key issue with TB is not necessarily the challenges in the discovery space. There are very good targets for innovative therapies in TB,” said Pieter Muntendam, BG’s president and CEO. “The problem is if you want to develop them preclinically and clinically, you have very cumbersome endpoints.”
According to Muntendam, a typical dose-ranging study takes six to nine months, “during which you need a large number of patients due to the heterogeneity of the disease, and these patients need to be compliant. So even if you have something that seems like a good drug, there is an incredibly difficult hurdle, even for dose-ranging studies.”
BG is looking for markers that could be assessed after two to four weeks of therapy that are predictive of the nine-month outcome. It may be easier to find predictive markers in a pathogenic infection like TB than in a condition that involves perturbations in the body’s normal function.
“We have reason to believe that we can find such markers,” Muntendam said. “What is good in cases like TB is that you have markers that could have pathogen origination, host-pathogen origination, or host origination.”
The primary value of biomarkers “is not as a surrogate endpoint for regulators,” Muntendam said. In the near term, “the primary value for organizations that are developing TB drugs is to very quickly understand if their drugs are working in a clinical environment. There is a tremendous internal value for the organization if you can do your preliminary dose ranging on biomarkers. Even if the regulators want you to do a typical dose-ranging study, it takes some of the experimentation out of the formal studies you have to conduct.”
The search for TB biomarkers could serve as broad proof of principle for infectious diseases, according to Muntendam. It could prompt research into markers for other infectious diseases that would facilitate both drug development and bedside treatment as physicians use biomarkers to guide clinical management of patients, he predicted.
Prior to the recently awarded Gates Foundation grant, the TB Alliance had raised about $70 million since its formation in 2000, including $15.5 million from the Rockefeller Foundation and $26.6 million from the U.K., the U.S., the Netherlands and Ireland.
Freire is looking to the G8 countries for the additional $100 million the alliance estimates it needs to bring a new combination therapy to market.