ATORvastatin in Pulmonary TUBerculosis

INTRODUCTION Tuberculosis is a chronic disease responsible for most deaths from infectious disease with an estimated I0 million cases and close to 2 million deaths globally. Despite the availability of therapy for TB, the scourge of the disease has not abated especially in the developing countries. The disease is caused by a bacterium called Mycobacterium tuberculosis, a non-spore forming intracellular organism. TB exists in two forms; primary and secondary infection. While primary infection most times goes unnoticed and are usually associated with non-specific symptoms, secondary infections are usually associated with profound symptoms and signs in various organs especially in the lungs. Majority of persons overcome primary infection but the tubercule bacilli may lie dormant in the macrophages. Secondary infection occurs as a result of either endogenous reactivation or exogenous re-infection. Pulmonary TB is responsible for more than 85% of the cases.

MTB infect and survive humans by evading the various immune defense systems. The organism accumulates and utilizes an abundant amount of lipids and cholesterol for its cell wall, and as a source of carbon for synthesis of virulence factors. Mycobacterium tuberculosis also utilizes cholesterol as a vehicle to enter macrophage, inhibit phagocytosis and inhibit growth and development of phagocytes. These greatly impairs the hydrolytic and antimicrobial properties and activities of phagocytes. Current therapy is as old as the disease itself; is of long duration, hence it is associated with poor compliance. This contributes to frequent relapses and emergence of resistant form of the disease. Average interval between one episode of TB and another ranges from 6-18 months after completion of therapy. Despite clinical cure, approximately half of patients have permanent lung damage. In Nigeria, TB is a major risk factor for Chronic Obstructive Pulmonary Disease, lung fibrosis/scarring and other diseases. It is clear that new and innovative therapeutic agents are needed to tackle this hydra- headed disease. In order to address these challenges, a lipid lowering agent, atorvastatin is being repurposed.

The use of statins have been demonstrated in infectious diseases and especially in tuberculosis than other organisms. In vitro studies have demonstrated that statins could strengthen the host response against M. tuberculosis and inhibit the activation of T cells induced by M. tuberculosis antigens. In another study, murine bone marrow-derived macrophages that were exposed to simvastatin and were infected with M. tuberculosis, showed a significant reduction in mycobacterial growth, without adverse effects on cell viability. Treatment of TB in animal model with statins and anti TB drugs showed that treatment with anti-TB drugs plus simvastatin reduced the percentage of relapses by 50% compared with treatment with only anti-TB drugs. Taken together, all these studies in animal model indicate that statins has anti-TB effect, reduces bacillary load, shortens the duration of therapy and decreases relapse rate when used with first-line anti-TB drugs.

Most of the clinical evidence on the role of statins in TB were from retrospective and nested case control studies from Asian continent. In one study in Taiwan, diabetic subjects older than 65 treated with statins had a lower risk of developing active tuberculosis, with a risk of 0.76 (95% CI, 0.60-0.97). Chronic use of statins (more than 90 days) was associated with the lowest risk (RR 0.62; 95% CI 0.53-0.72) as shown in another study.

The ATORTUB investigators recently completed two phase 2 studies to assess the safety, tolerability and efficacy of atorvastatin administered with the current standard of care. The first study was a phase IIA study involving 40 patients randomized to receive standard of care alone and standard of care with oral (40mg) dose atorvastatin. Primary outcome at 2 weeks was safety, tolerability and early bactericidal activity over a 2 week period. The study showed that atorvastatin was generally safe and well tolerated. The rate of decline of colony forming unit was higher among the atorvastatin group. Even though there was no early bactericidal activity demonstrated at 2 weeks, atorvastatin group had significantly number of participants with more than 0.5 log10 decline in colony forming unit. This was quite significant. At the phase IIB study, 150 eligible participant's were randomly assigned to either of the two arms. All the participants had rifampicin sensitive active non complicated TB. Other drug resistance testing were not done. Oral dose of 40mg of atorvastatin was given for 2 months together with standard of care drugs and afterwards the standard of care drugs were continued for the patients to complete 6 months of therapy. Primary outcome were safety and tolerability atorvastatin , efficacy measured by the number of sputum conversion at 2 months. Secondary outcome was chest x-ray severity score at 2 months. AT the end of the phase IIB trial, it was shown that atorvastatin was generally safe and in fact participants in that group had reduced incidence of peripheral neuropathy. More participants achieved sputum conversion compared with the standard of care group. The mean improvement in chest x-ray severity score was higher in the experimental group Atorvastatin in combination with standard antituberculosis drugs achieved a significantly higher rate of sputum culture negativity and reduction in mycobacterial burden in sputum at 2 months compared with antituberculosis drugs alone. The difference in sputum negativity and the mean fall in colony forming unit per ml of sputum per month were significantly higher among the intervention group. The use of atorvastatin was also significantly associated with a negative sputum result. These may be indicative of the anti-mycobactericidal effect of atorvastatin, which had been earlier reported in murine models, other invitro studies and consistent with the earlier phase IIA result .

The ATORTUB investigators therefore concluded that atorvastatin has beneficial microbiological and radiological impacts in tuberculosis and warrants further studies.

Though, the phase IIB study reported positive findings that suggests the beneficial role of atorvastatin, however, before moving to a more expensive phase III study, important information relating to the clinical trial needs to be answered. For example, there is a need to establish the time to stable sputum conversion. This will be useful in determining the effective duration of atorvastatin containing regimen. In addition, evaluating the regimen among unbiased and diverse groups of patients including those with HIV, DM, hypertension and possibly children will be helpful and required. Even though, the dose we used was effective, conducting pk-pd evaluations at different doses and correlating these with outcomes of the trial will be essential.

Phase IIC also referred to as Selection Trial with Extended follow-up STEP, has been devised as a pilot phase III where patients are studied for longer period than the usual phase IIB and additional data that will justify and ensure a successful phase III trial are obtained. Patients are followed up for a fairly longer time in phase IIC , 12 months post randomization.

2. Study Design

Experimental design/Research Plan This is a multicenter, randomized, controlled, open-label, 4-arm, phase IIC superiority trial.

For the phase III aspect, the study will be fully international and multicenter.

Phase IIC will seek to determine the safety and efficacy of different doses of atorvastatin containing regimen , the time to sputum culture conversion, time to decline in Chest x-ray severity score and improvement in lung function parameters by atorvastatin at mentioned doses in combination with standard anti-TB regimen in 440 patients.

Consented and eligible patients aged12 -65 years with active tuberculosis will be recruited and have study-specific procedures initiated at enrollment / Screening visit. At screening visit, participants will be interviewed for demographics, contact information, medical history. They will have their anthropometry documented, will be screened for HIV, Diabetes and Pregnancy (in females), and have sputum collected for mycobacterial smear and culture.

At baseline visit (visit at which study drug is initiated), sputum will be collected for mycobacterial smear and culture, blood sample for complete blood count, serum or plasma for alanine aminotransferase (ALT), total bilirubin, creatinine, albumin, and potassium, complete lipid profile, creatine phosphokinase, unless results from those tests performed within fourteen days prior to screening are available. Sweat test and lung function test will be performed prior randomization. In this visit (baseline), participants will be randomized to receive either 20/40/60mg of daily treatment with atorvastatin for 16 weeks (from the beginning of standard of care treatment) with standard anti-TB regimen (2RHZE/4RH) for 24weeks (6 months) or the standards anti-TB drugs alone for 24 weeks (6 months). Randomization will be stratified by site, by HIV status (HIV-uninfected vs. HIV- infected with CD4 T cell count greater than or equal to 200 cells/mm3 vs. HIV-infected with CD4 T cell count less than 200 cells/mm3) and by DM status (DM patients vs. non-DM) and will follow a predefined allocation ratio of 1:1:1:1. Thereafter, participants will be followed up closely up to 12 months post randomization (i.e. study specific procedures will be carried out at weeks 2,4,6,8,10,12, 16, 22, 24; months 8, 10 and 12 post randomization according to study protocol). During this period, the number and types of Adverse Events in the participants will also be reported and documented.