Sirturo, the first new Tuberculosis drug in 40 years, brings new hope to patients
Tuberculosis (TB), though largely treatable by a select combination of four first-line medications, has never been eradicated and is still a major public health threat worldwide. The World Health Organization (WHO) reported that this infectious air-borne disease caused 1.4 million deaths and 8.7 million new and relapse infections in 2011. This makes the disease the second biggest killer in the world (after HIV) attributable to a single infectious agent. In the U.S., the rate of TB infection is relatively low with 10,528 new cases reported in the same year. Eighty-four countries have reported cases of multi-drug resistant TB (MDR-TB) but since only 1 in 20 TB patients are tested, the incidence is probably much higher than commonly recognized. Drug resistant TB accounts for 3.7% of all new cases and 20% of previously treated cases worldwide. People in developing countries are at a much greater risk of contracting the disease. According to the WHO, in 2011,
- 80% of TB cases were found in 22 countries concentrated in Asia and Africa, and
- 95% of TB-related deaths were reported by developing / undeveloped nations.
Despite the prevalence of the disease, less than 1/5 of those infected receive treatment either due to the lack of proper diagnosis or the lack of affordable / accessible medications. People who do get treatment sometimes cannot follow through with their regimen, and as a result, develop a more severe form of TB. Multi-drug-resistant TB occurs when the new mutated strain becomes resistant to the two most powerful anti-TB drugs – isoniazid and rifampin. Latest statistics show 630,000 people worldwide have MDR-TB and 2 million more patients, if predictions hold, will develop this form of the disease between 2011 and 2015. Ninety-eight cases of drug resistant TB were reported in the U.S. in 2011. While regular TB patients on a consistent antibiotic regimen start to recover after 6-12 months, MDR-TB patients must endure a two-year course of treatment involving up to 20 pills a day, 8 months-worth of injections and painful side effects. The cost of treating drug resistant TB can be 200 times greater than the standard treatment. To make matters worse, this costly MDR-TB regimen is only successful about 50% of the time.
For decades, MDR-TB patients struggled with the absence of effective medications. Janssen Therapeutics, the pharmaceutical research division of Johnson & Johnson, just recently came out with Sirturo (bedaquiline), a drug that specifically targets MDR-TB bacteria. This is the first drug to be approved for MDR-TB and the first new TB drug to be approved in 40 years. It works in a completely new way than all the other TB drugs currently on the market. It is designed to be used only in combination with other drugs. The FDA approved the drug under an accelerated review program because Sirturo qualified for fast-track designation, priority review and orphan-product designation. Under this expedited pathway, this drug was approved in only 6 months. According the agency’s news release, the drug fulfills “an unmet medical need, has the potential to provide safe and effective treatment where no satisfactory alternative therapy exists, and is intended to treat a rare disease.” Traditionally, the FDA approves a drug after a three-stage process, but J&J’s new product got the nod while still in the second phase of clinical trials. The Phase 2 trial showed a median recovery time of 83 days in the first trial and 57 days in the second trial for the Sirturo group compared to 125 days for the placebo group. Consumer advocacy groups, however, voiced concern over the drug’s approval because the mortality rate in the testing group was worrisomely high. Nine patients died while on Sirturo versus just two in the placebo group. Five of the 9 deaths were seemingly unrelated to TB so whether the drug caused the other four deaths is unclear.
J&J cautions the product should only be used when no other treatment options are available and will place a black box warning on Sirturo outlining its serious side effects such as heightened liver toxicity and abnormal heart activity. Hopefully, one of the ten new TB drugs in clinical trials or one of the 12 TB vaccine candidates being tested will join Sirturo in the battle against this rising health menace. Since costs for TB diagnosis and control are expected to reach $8 billion worldwide by 2015, having additional arrows in our quiver of treatment options is very desirable.
J&J has not yet announced the price at which it will sell Sirturo, but has indicated that it does not expect the drug to be a big seller in the United States since fewer than 100 Americans have MDR-TB. However, approval of the drug by the FDA is expected to increase chances for approval in other countries where the disease strain is much more prevalent. Whether the drug is priced affordably will be a big factor in determining whether it makes meaningful progress in reducing the 630,000 worldwide cases of MDR-TB.