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At long last, a new weapon against tuberculosis

Posted on behalf of Becky Summers.

The fight against an ancient disease has gained its first genuinely new weapon in 50 years. Using a new fast-track approval process, the US Food and Drug Administration (FDA) has approved a drug to tackle multiple-drug-resistant strains of tuberculosis (TB).

The drug, named bedaquiline and marketed as Sirturo, is produced by the pharmaceutical company Janssen Therapeutics. It received the FDA’s approval on 28 December.

TB is one of the world’s leading killers, and is the leading cause of death among people with HIV. But it is a tale of two sides. Ordinarily, Mycobacterium tuberculosis, the bacterium that causes TB, is treatable, although drug regimens can last up to six months. But strains have evolved to resist the drugs used to combat it, such as isoniazid and rifampicin.

The new drug inhibits the key enzyme adenosine triphosphate synthase, which TB needs to replicate and spread throughout the body. In two separate phase II clinical trials, Sirturo was found to reduce average treatment times for patients with TB from a median of 125 days to 57 and 83 days, respectively.

The FDA vetted Sirturo through an accelerated approval programme, which allows a drug to go onto the market earlier than would normally be allowed, if it can help to treat patients who are dying and for whom no other treatments are available.

But there are risks. The drug can cause abnormal and potentially fatal heart rhythms. In the trials, nine patients who received Sirturo died, in comparison with only two patients who died in the control group. All of the control-group deaths were TB related, but in the Sirturo group the causes of death were unclear in four cases. Patients also reported other side effects, such as  nausea, joint pain and headaches.

Approval of the new drug comes amid pressures on the FDA to loosen the requirements around clinical trials for antibiotic drugs. As new drug-resistant bacteria arise, not only in TB but in a multitude of other diseases, Janet Woodcock, head of the FDA’s centre for drug evaluation and research,  pledged last year to “reboot” the approval of new antibiotics.

On 9 July, the US Congress passed a set of measures offering incentives for companies to work on antibiotic development. “The goal there is to try to put some more enticements on the table for companies to develop new antimicrobial drugs,”  Brad Tebbets, an infectious-disease analyst at Global Data, a London-based research firm that tracks the pharmaceutical industry, told Nature in August. Drugs that treat drug-resistant bacteria, such as Sirturo, receive priority review and fast-track status, and can be eligible for up to five additional years of market exclusivity.

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