(Reuters Health) - The new anti-tuberculosis drug combination of bedaquiline, pretomanid and linezolid cures 90% of people with deadly drug-resistant TB if given for six months, researchers report in The New England Journal of Medicine.

“This is extremely significant, probably one of the biggest advances in TB therapeutics since the 1970s,” said Dr. Richard Chaisson, director of the Center for Tuberculosis Research at Johns Hopkins University, in Baltimore, who was not involved in the study.

A 90% success rate is typically only seen when TB responds to conventional therapy.

When TB is resistant, the success rate is well below 50%. It averages 14% in South Africa, where the new trial was done.

“These results are very compelling, better than I ever expected,” coauthor Dr. Francesca Conradie told Reuters Health by telephone.

Patients often showed improvement within a week or two.

Current therapy requires taking up to seven drugs and enduring many side effects for at least 18 months.

“The treatment for drug-resistant TB and extensively drug-resistant TB for the past 20 years has been this horrible concoction of highly-toxic and weakly-effective drugs. Half the people developed hearing loss. Everybody got nausea and vomiting,” Chaisson told Reuters Health by phone. “So to come along with a treatment that is all oral, only takes 6 months and has a 90% cure rate is nothing short of spectacular.”

Tuberculosis kills an estimated 1.5 million annually. Of about 10 million new cases each year, roughly a half million are drug resistant.

Getting better drugs to fight drug-resistant TB has been a difficult challenge. Pretomanid is one of only three new TB drugs approved by the U.S. Food and Drug Administration in more than 40 years.

Tuberculosis bacteria grew resistant to conventional therapy partly because not enough was done to deal with cases where the standard combination was not working, Dr. Guy Thwaites of the University of Oxford and Dr. Payam Nahid of the University of California, San Francisco write in an editorial.

More funds need to be invested to ensure TB bacteria don’t develop resistance to this treatment as well, they write.

“We need to guard this regimen like a pearl of great price,” said Conradie, who is deputy director of the clinical HIV research unit at the University of Witwatersrand.

The new open-label trial was done on 109 volunteers at three South African sites; 51% were HIV-positive and 84% had holes in the lung visible on chest x-rays. The patients had been living with TB for as long as 11.75 years, although the median was 12 months.

Only 10% had treatment failure or relapsed during the six months after treatment ended.

The most significant side effects were related to linezolid, with 81% of patients having mild to moderate nerve tingling and 48% experiencing low blood counts.

The researchers characterized those problems as “manageable” and said there might be ways to change the dose to alleviate them.

No patients dropped out of the trial because of compliance,” coauthor Dr. Melvin Spigelman, president of the non-profit TB Alliance, which financed the study, told Reuters Health by phone.

The new regimen is expected to cost far less than the other, longer treatments for extensively drug-resistant TB, according to the TB Alliance.

“It is critically important that surveillance for the development of resistance be improved around the world and testing be more affordable and available,” Spigelman said. “It would be naive to believe we can abolish resistance, but we can certainly do a much better job than has been done historically.”

SOURCE: bit.ly/2uF5SYP and bit.ly/2IjBFlz The New England Journal of Medicine, online March 4, 2020.