The TB activist agenda

1. Vaccines

Two vaccines have entered the second half of Phase II clinical trials in the past year. This is when the vaccine is given to a larger group of people to see if it is effective at a prescribed dose, and to further evaluate its safety.

Activists are pushing for an alternative to the only TB vaccine available today - Bacille Calmette-Guerin (BCG) - which has been in use for nearly 90 years. BCG has become a standard part of national immunization programmes in many countries, but the immunity it offers wanes after childhood.

A new TB vaccine would have to offer lasting immunity, be heat-stable and easy to administer. It should also protect against pulmonary TB as well as TB in other organs.

2. Diagnostics

A two-hour TB test - GeneXpert - which can also detect drug-resistant TB, drastically cut the time patients had to wait for results when it was released in 2010. Some countries with a high TB burden, like South Africa, have implemented wide use of the coffee-maker sized machine that uses cartridges to perform the test. Others, like Kenya, have been slower off the mark.

By March 2012, South Africa accounted for about half of the more than 863,000 cartridges procured globally, according to data presented at the South African TB Conference by Colleen Daniels, the Treatment Action Group's TB/HIV project director.

Although the World Health Organization ranks Kenya as having a higher TB burden than South Africa, Kenya had only procured about 34,000 of the cartridges by that time, Daniels told IRIN/PlusNews.

To help countries like Kenya expand their use of GeneXpert, the international health financing mechanism, UNITAID, announced on 13 June 2012 that together with the US government and the Bill and Melinda Gates Foundation, it had reached an agreement with the GeneXpert manufacturer, Cepheid, allowing some high-burden countries like Kenya, South Africa and Zimbabwe to purchase cartridges at a reduced price of US$10. 

Erica Lessem, the assistant director of Treatment Action Group's TB/HIV project, said new diagnostics that are fast, effective and affordable are still needed. "GeneXpert is certainly no panacea," she told IRIN/PlusNews. "We need to continue putting pressure on diagnostic makers for point-of-care tests that can be used in peripheral health clinics."

Countries like South Africa have rolled out the GeneXpert machine to help boost capacity in existing TB laboratories, but new tests would ideally move away from examining sputum samples for TB and towards substances that are easier to collect, such as urine, Lessem said. Patients living with HIV and children often find sputum, or mucus coughed up from the lower airways, difficult to produce.

3. New, better, shorter courses of drugs and compassionate use

Two drugs that could treat multidrug-resistant (MDR-TB) and extensively drug-resistant TB (XDR-TB) - Delamanid and Bedaquiline - have entered late-stage clinical trials.

Delamanid, manufactured by the Otsuka Pharmaceutical Group, recently filed for approval of the medication by the European Medicines Agency (EMA). This is the first new TB drug to apply for regulatory approval in more than 40 years, Lessem told the South African TB Conference, noting that it was particularly promising because there would be no pre-existing resistance to it. 

Lessem says TB activists are fighting to expand pre-approval use - or "compassionate use" - of these drugs for patients with drug-resistant TB who may have run out of options. The compassionate use concept allows patients earlier access to promising new drug candidates still in clinical trials when the normally available treatment options have failed.

Compassionate use of Bedaquiline - the other drug that could help patients with drug-resistant TB - was sought earlier this year from South Africa's drug regulator, the Medicines Control Council (MCC), by civil society groups such as South Africa's Treatment Action Campaign (TAC) and the HIV Clinicians Society of Southern Africa.

In an open letter to the MCC, the activists noted that Bedaquiline's potential for improving cure rates and shortening treatment time "far outweighs any safety concerns, especially as evidence indicates that Bedaquiline's safety profile is far superior to that of many existing second-line treatment options." Tibotec, the pharmaceutical company that developed Bedaquiline, made the drug available, free of charge, under compassionate use criteria in mid-2011.

The Medicines Control Council rejected the request, saying that while the evidence of patient need was compelling, there was insufficient data on the drug and the move was premature.

Activists are also pushing for drug-resistant TB treatment to be shorter, with fewer pills, less side effects and greater compatibility with HIV treatment. According to Lessem, some forms of treatment for drug-resistant TB are not recommended for use with antiretrovirals.

Finally, with almost all medicines to treat drug-resistant TB designed for adults, paediatric formulations that are easier to administer are urgently needed. This would include scoring pills so that they can be easily broken up into smaller, child-friendly doses, and making them available in granular form for mixing into food. Lessem said there needs to be a stronger push for paediatric clinical trials, which are often not only neglected, but hard to navigate through regulatory bodies.

PlusNews

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