An Open-label RCT to Evaluate a New Treatment Regimen for Patients With Multi-drug Resistant Tuberculosis

Background:

TB is completely out of control in South Africa and is now officially the most common cause of death in this country. Alarmingly, the gravity if this pandemic has now been compounded by the emergence of multidrug-resistant TB (MDR-TB), which constitutes resistance to the two most potent anti-tuberculous drugs, namely rifampicin and isoniazid . XDR-TB refers to resistance to rifampicin, isoniazid, any fluoroquinolone, and any second line injectable drug (amikacin, kanamycin, or capreomycin). MDR-TB is a burgeoning epidemic in South Africa, with rates trebling over the last decade. It is of considerable concern because mortality is high (up to 50% in South Africa) and it often affects economically active young adults. It is also a major threat to health care workers in South Africa. We recently showed a rate in SA health care workers 6 fold higher than the general population further exacerbating the shortage of this critical workforce in the country. The increasing cost to manage this disease is unsustainable.

Although drug-resistant TB comprises less than 2% of the total caseload in the country (approximately ½ million patients with TB treated per year), it consumes almost 40% of the total national TB programme budget, and more than 60% of the total TB drug budget. This is not sustainable and drug-resistant TB therefore has the capacity to destabilise functional TB control programmes in many countries in Africa.

The treatment of MDR-TB is arduous, with a six to eight month intensive phase of daily painful injections of Kanamycin combined with oral pyrazinamide, a fluoroquinolone (moxifloxacin or levofloxacin), prothionamide and either cycloserine or para-aminosalicylic acid (if cycloserine cannot be used). Treatment continues for 18 months after consecutive negative sputum cultures, and lasts at least 20 months. There are substantial drug-associated toxicities and adverse events that frequently lead to interruption or cessation of treatment.

This study proposes to test the efficacy of a new drug regimen for the treatment of MDR-TB which is of short term duration and which does not contain an injectable drug, thus making treatment easier to administer and thereby potentially increasing compliance. All the drugs will be available to the NTP if the study is shown to be successful. This regimen will comprise linezolid, bedaquiline, levofloxacin, PZA and either ethionamide or high dose INH or teridazone. A gene-directed diagnostic approach (mutational analysis) will be used in the interventional arm to individualise therapy and to inform on the use of high dose INH versus ethionamide. If both mutations are present then to administer teridazone.

Furthermore, in the proposed study the key aim is to test a regimen (rather than an individual drug) and will look at how the outcomes (24 month), including treatment completion/cure (i.e. treatment success which is the primary outcome) and mortality, are impacted. It is expected that introduction of a shortened effective regimen will reduce drop out and drastically reduce mortality and on-going transmission. Moreover, the rates of XDR-TB and TDR-TB may also decline.

The study will be conducted at 5 trial sites in South Africa that are designated MDR-TB treatment facilities and it many cases patients will be recruited from the satellite clinics of these centres reflecting the decentralized MDR-TB program. All the sites have the necessary expertise and facilities to carry out the proposed study. The study is a fully conceived and funded within South Africa.