A shorter MDR-TB treatment regimen can improve treatment adherence

Urvashi Prasad, CNS Correspondent, India
India has over 2 million new cases of TB—a disease that is treatable and curable— every year. Yet, many succumb to it and many encounter drug resistance. A person with multi drug-resistant TB (MDR-TB) is not responsive to at least one of the two main TB drugs. Studies have shown that MDR-TB is found in approximately 3% of new TB cases and between 12%-17% of re-treatment cases. In India given the high burden of TB, this translates into large numbers in absolute terms.

The conventional treatment regimen for MDR-TB lasts between 18-24 months and involves the administration of a combination of pills and injections. This makes the treatment very complex and yields low cure rates of 48% globally. Given that patients have to take second-line drugs with adverse side-effects for a prolonged period of time, the compliance with this treatment regimen is often quite poor. Many patients are either lost to follow-up or their treatment is interrupted. The new treatment regimen (more commonly called the Bangladesh regimen), on the other hand, can be completed within 12 months. It is not only far less expensive but can also improve outcomes by enabling better adherence to treatment and a reduction in loss to follow-up. The shorter regimen is suitable for patients who are suffering from uncomplicated MDR-TB and are not resistant to second-line drugs. Programmatic studies evaluating the shorter regimen have been carried out in 10 countries across the world involving 1,200 patients.

Several studies are also underway to assess the efficacy of new drug combinations for MDR-TB treatment in India. One study is recruiting patients on the usual 24-month treatment along with those who are being put on the drug Bedaquiline. Another cohort of patients is likely to be part of clinical study to assess the Bangladesh regimen. Another short TB drug regimen, developed by TB Alliance, called PaMZ, has shown encouraging results. This is a three-drug regimen comprising two candidate drugs pretomanid (Pa) and moxifloxacin (M) that are not yet licensed for use against TB, and one antibiotic, pyrazinamide (Z), which is already in use in TB treatment. The therapy is intended for those patients whose TB infections are sensitive to the three drugs, including people with drug-sensitive TB and MDR-TB. Phase 2b clinical studies showed the potential of PaMZ to treat drug-sensitive TB and some cases of MDR-TB in 4 to 6 months, irrespective of their HIV status.

The global phase 3 clinical study named STAND (Shortening Treatment by Advancing Novel Drugs) in patients who are currently considered to have either drug-sensitive or MDR-TB. Enrolment for the global phase 3 clinical study of PaMZ is already underway. It expects to enrol 1,500 patients across 15 countries. Patients from 5 states of India (Maharashtra, Delhi, Gujarat, Tamil Nadu and West Bengal) are also expected to be enrolled for this study. If successful in this Phase 3 trial, the PaMZ regimen would eliminate the need for injectable drugs and reduce the cost of MDR-TB therapy by more than 90% in those TB patients who are sensitive to the three drugs. During a webinar organised by CNS, Dr ID Rusen, Senior Vice President (Research and Development), International Union Against TB and Lung Disease (The Union), highlighted the need for evaluating shortened treatment regimens for MDR-TB in different settings. He emphasised the importance of designing both observational studies and randomised controlled trials.

Given the significant burden of TB and MDR-TB in India coupled with high treatment default rates, it is vital for India to evaluate the shorter regimens in various settings and add to the evidence base for the impact of these regimens on reducing TB related mortality and morbidity.

Urvashi Prasad, Citizen News Service - CNS
July 13, 2016