Amina Jindani

Two 8-month regimens of chemotherapy for treatment of newly diagnosed pulmonary tuberculosis: international multicentre randomised trial

BACKGROUND A WHO-recommended 8-month regimen based on ethambutol and isoniazid was evaluated in a randomised clinical trial against a 6-month standard regimen. METHODS 1355 patients with newly diagnosed smear-positive pulmonary tuberculosis were randomly assigned one of three regimens: daily ethambutol, isoniazid, rifampicin, and pyrazinamide for 2 months, followed by ethambutol and isoniazid for 6 months (2EHRZ/6HE); the same drugs but given three times weekly in the initial intensive phase (2[EHRZ]3/6HE); or the same initial intensive phase as the first regimen, followed by 4 months of daily rifampicin and isoniazid (2EHRZ/4HR). Follow-up was to 30 months after the start of chemotherapy. Sputum was regularly examined by microscopy and culture. Unfavourable outcome was defined as failure during treatment or relapse afterwards. Analyses were by intention to treat. FINDINGS At 2 months, a significantly higher proportion of patients assigned the daily intensive phase than of those assigned the three-times-weekly regimen were culture negative (700/828 [85%] vs 333/433 [77%], p=0.001). 12 months after the end of chemotherapy, the proportions of unfavourable outcomes were 36 of 346 (10%) with 2EHRZ/6HE, 48 of 351 (14%) with 2(EHRZ)3/6HE, and 17 of 347 (5%) with 2EHRZ/4HR. Both 8-month regimens were significantly inferior to the control 6-month standard regimen (difference between control and 2EHRZ/6HE 5.5% [95% CI 1.6 to 9.4]; between control and 2(EHRZ)3/6HE 8.8% [4.5 to 13.0]). Adverse effects leading to interruption of treatment for 7 days or longer occurred in 28 patients (12 2EHRZ/6HE, five 2[EHRZ]3/6HE, 11 2EHRZ/4HR). INTERPRETATION The results of this study must be taken into account in recommendations on management of new cases of smear-positive tuberculosis.

High-Dose Rifapentine with Moxifloxacin for Pulmonary Tuberculosis

BACKGROUND Tuberculosis regimens that are shorter and simpler than the current 6-month daily regimen are needed. METHODS We randomly assigned patients with newly diagnosed, smear-positive, drug-sensitive tuberculosis to one of three regimens: a control regimen that included 2 months of ethambutol, isoniazid, rifampicin, and pyrazinamide administered daily followed by 4 months of daily isoniazid and rifampicin; a 4-month regimen in which the isoniazid in the control regimen was replaced by moxifloxacin administered daily for 2 months followed by moxifloxacin and 900 mg of rifapentine administered twice weekly for 2 months; or a 6-month regimen in which isoniazid was replaced by daily moxifloxacin for 2 months followed by one weekly dose of both moxifloxacin and 1200 mg of rifapentine for 4 months. Sputum specimens were examined on microscopy and after culture at regular intervals. The primary end point was a composite treatment failure and relapse, with noninferiority based on a margin of 6 percentage points and 90% confidence intervals. RESULTS We enrolled a total of 827 patients from South Africa, Zimbabwe, Botswana, and Zambia; 28% of patients were coinfected with the human immunodefiency virus. In the per-protocol analysis, the proportion of patients with an unfavorable response was 4.9% in the control group, 3.2% in the 6-month group (adjusted difference from control, -1.8 percentage points; 90% confidence interval [CI], -6.1 to 2.4), and 18.2% in the 4-month group (adjusted difference from control, 13.6 percentage points; 90% CI, 8.1 to 19.1). In the modified intention-to-treat analysis these proportions were 14.4% in the control group, 13.7% in the 6-month group (adjusted difference from control, 0.4 percentage points; 90% CI, -4.7 to 5.6), and 26.9% in the 4-month group (adjusted difference from control, 13.1 percentage points; 90% CI, 6.8 to 19.4). CONCLUSIONS The 6-month regimen that included weekly administration of high-dose rifapentine and moxifloxacin was as effective as the control regimen. The 4-month regimen was not noninferior to the control regimen. (Funded by the European and Developing Countries Clinical Trials Partnership and the Wellcome Trust; RIFAQUIN Current Controlled Trials number, ISRCTN44153044.).

Efficacy and Safety of a 4-Drug Fixed-Dose Combination Regimen Compared With Separate Drugs for Treatment of Pulmonary Tuberculosis: The Study C Randomized Controlled Trial

CONTEXT Fixed-dose combinations (FDCs) of drugs for treatment of tuberculosis have been advocated to prevent the emergence of drug resistance. OBJECTIVE To assess the efficacy and safety of a 4-drug FDC for the treatment of tuberculosis. DESIGN, SETTING, AND PATIENTS The Study C trial, a parallel-group, open-label, noninferiority, randomized controlled trial conducted in 11 sites in Africa, Asia, and Latin America between 2003 and 2008. Patients were 1585 adults with newly diagnosed smear-positive pulmonary tuberculosis. INTERVENTIONS Patients were randomized to receive daily treatment with 4 drugs (rifampicin, isoniazid, pyrazinamide, ethambutol) given as an FDC (n = 798 patients) or separately (n = 787) in the 8-week intensive phase of treatment. MAIN OUTCOME MEASURE Favorable treatment outcome, defined as negative culture result at 18 months post randomization and not having already been classified as unfavorable. Noninferiority was dependent on consistent results from a per-protocol and modified intention-to-treat analysis, using 2 different models for the latter, classifying all changes of treatment or refusal to continue treatment (eg, bacteriological failure/relapse, adverse event, default, drug resistance) as unfavorable (model 1) and classifying changes of treatment for reasons other than therapeutic outcomes according to their 18-month bacteriological outcome if available (post hoc model 2). The prespecified noninferiority margin was 4%. RESULTS In the per-protocol analysis, 555 of 591 patients (93.9%) had a favorable outcome in the FDC group vs 548 of 579 (94.6%) in the separate-drugs group (risk difference, -0.7% [90% confidence interval {CI}, -3.0% to 1.5%]). In the model 1 analysis, 570 of 684 patients (83.3%) had a favorable outcome in the FDC group vs 563 of 664 (84.8%) in the separate-drugs group (risk difference, -1.5% [90% CI, -4.7% to 1.8%]). In the post hoc model 2 analysis, 591 of 658 patients (89.8%) in the FDC group and 589 of 647 (91.0%) in the separate-drugs group had a favorable outcome (risk difference, -1.2% [90% CI, -3.9% to 1.5%]). Adverse events related to trial drugs were similarly distributed among treatment groups. CONCLUSIONS Compared with a regimen of separately administered drugs, a 4-drug FDC regimen for treatment of tuberculosis satisfied prespecified noninferiority criteria in 2 of 3 analyses. Although the results do not demonstrate full noninferiority of the FDCs compared with single drugs given separately using the strict definition applied in this trial, use of FDCs is preferred because of potential advantages associated with the administration of FDCs compared with separate-drug formulations. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00216333.

Moxifloxacin Population Pharmacokinetics in Patients with Pulmonary Tuberculosis and the Effect of Intermittent High-Dose Rifapentine

ABSTRACT We described the population pharmacokinetics of moxifloxacin and the effect of high-dose intermittent rifapentine in patients with pulmonary tuberculosis who were randomized to a continuation-phase regimen of 400 mg moxifloxacin and 900 mg rifapentine twice weekly or 400 mg moxifloxacin and 1,200 mg rifapentine once weekly. A two-compartment model with transit absorption best described moxifloxacin pharmacokinetics. Although rifapentine increased the clearance of moxifloxacin by 8% during antituberculosis treatment compared to that after treatment completion without rifapentine, it did not result in a clinically significant change in moxifloxacin exposure.

A randomised Phase II trial to evaluate the toxicity of high-dose rifampicin to treat pulmonary tuberculosis.

SETTING Randomised Phase IIB clinical trial. OBJECTIVES To assess whether increasing the dose of rifampicin (RMP) from 10 mg/kg to 15 or 20 mg/kg results in an increase in grade 3 or 4 hepatic adverse events and/or serious adverse events (SAE). METHODS Three hundred human immunodeficiency virus negative patients with newly diagnosed microscopy-positive pulmonary tuberculosis (TB) were randomly assigned to one of three regimens: 1) the control regimen (R10), comprising daily ethambutol (EMB), isoniazid (INH), RMP and pyrazinamide for 8 weeks, followed by INH and RMP daily for 18 weeks; 2) Study Regimen 1 (R15), as above, with the RMP dose increased to 15 mg/kg body weight daily for the first 16 weeks; and 3) Study Regimen 2 (R20), as above, with RMP increased to 20 mg/kg. Serum alanine transferase (ALT) levels were measured at regular intervals. RESULTS There were seven grade 3 increases in ALT levels, 1/100 (1%) among R10 arm patients, 2/100 (2%) in the R15 arm and 4/100 (4%) in the R20 arm (trend test P = 0.15). One (R15) patient developed jaundice, requiring treatment modification. There were no grade 4 ALT increases. There was a non-significant increase in culture negativity at 8 weeks with increasing RMP dosage: 75% (69/92) in R10, 82.5% (66/80) in R15 and 83.1% (76/91) R20 patients (P = 0.16). CONCLUSIONS No significant increase in adverse events occurred when the RMP dose was increased from 10 mg/kg to 15 mg/kg or 20 mg/kg.

Moxifloxacin Population Pharmacokinetics and Model-Based Comparison of Efficacy between Moxifloxacin and Ofloxacin in African Patients

ABSTRACT Pharmacokinetic exposure and the MIC of fluoroquinolones are important determinants of their efficacy against Mycobacterium tuberculosis. Population modeling was used to describe the steady-state plasma pharmacokinetics of moxifloxacin in 241 tuberculosis (TB) patients in southern Africa. Monte Carlo simulations were applied to obtain the area under the unbound concentration-time curve from 0 to 24 h (fAUC0–24) after daily doses of 400 mg or 800 mg moxifloxacin and 800 mg ofloxacin. The MIC distributions of ofloxacin and moxifloxacin were determined for 197 drug-resistant clinical isolates of Mycobacterium tuberculosis. For a specific MIC, the probability of target attainment (PTA) was determined for target fAUC0–24/MIC ratios of ≥53 and ≥100. The PTAs were combined with the MIC distributions to calculate the cumulative fraction of response (CFR) for multidrug-resistant (MDR) Mycobacterium tuberculosis strains. Even with the less stringent target ratio of ≥53, moxifloxacin at 400 mg and ofloxacin at 800 mg achieved CFRs of only 84% and 58% for multidrug-resistant isolates with resistance to an injectable drug, while the 800-mg moxifloxacin dose achieved a CFR of 98%. Using a target ratio of ≥100 for multidrug-resistant strains (without resistance to injectable agents or fluoroquinolones), the CFR was 88% for moxifloxacin and only 43% for ofloxacin, and the higher dose of 800 mg moxifloxacin was needed to achieve a CFR target of >90%. Our results indicate that moxifloxacin is more efficacious than ofloxacin in the treatment of MDR-TB. Further studies should determine the optimal pharmacodynamic target for moxifloxacin in a multidrug regimen and clarify safety issues when it is administered at higher doses.

Results at 30 months of a randomised trial of two 8-month regimens for the treatment of tuberculosis.

SETTING An 8-month isoniazid (INH, H) and ethambutol (EMB, E) based regimen recommended by the World Health Organization (WHO) had never been evaluated in a randomised controlled multicentre trial. OBJECTIVE To compare, in a non-inferiority study design, two 8-month INH+EMB-based regimens with a standard INH and rifampicin (RMP, R) based regimen. DESIGN A total of 1355 patients with newly diagnosed smear-positive pulmonary tuberculosis were randomly allocated to receive 1) daily EMB, INH, RMP and pyrazinamide (PZA, Z) for 2 months, followed by EMB+INH for 6 months (2EHRZ/6HE); 2) the same drugs in the intensive phase but given three times weekly, followed by the same continuation phase of daily EMB+INH (2(EHRZ)(3)/6HE); or 3) a control regimen with the same intensive phase as in regimen 1, followed by 4 months of daily RMP+INH (2EHRZ/4HR). All patients were to be seen and sputum examinations for microscopy and culture carried out at regular intervals up to 30 months after randomisation. RESULTS At 30 months, failure/relapse rates were 11.7% of 281 2EHRZ/6HE, 15.3% of 301 2(EHRZ)(3)/6HE and 6.0% of 282 2EHRZ/4HR patients (χ(2), 2 degrees of freedom = 12.8, P = 0.002). CONCLUSION These results confirm earlier findings demonstrating the inferiority of the INH+EMB-based regimens to the standard 6-month regimen. The WHO has withdrawn its recommendation of these regimens.

Results at 30 months of a randomised trial of FDCs and separate drugs for the treatment of tuberculosis.

Study C was an open-label, non-inferiority, randomised controlled trial of fixed-dose combination (FDC) or separate drugs given during the intensive phase of treatment to 1585 patients with smear-positive pulmonary tuberculosis conducted at 11 sites in Africa, Asia and Latin America. Thirty months post-randomisation, the failure/relapse rates in the per protocol population were 7.4% of 591 patients on FDCs and 6.5% of 587 patients on separate drugs; the site-adjusted difference was 0.3% (90%CI -1.8 to 2.3). In the modified intention-to-treat analysis, the corresponding results were respectively 17.9% of 683 and 16.1% of 671; the site-adjusted difference was 2.0% (90%CI -1.2 to 5.2).

Challenges to the development of new drugs and regimens for tuberculosis

In spite of having effective, safe treatment for tuberculosis, the prevalence, incidence and mortality remain high. One of the ways to improve control of the disease is to reduce treatment duration either with currently used drugs or with the development of new drugs. These will all require clinical testing for safety and efficacy. The increasing complexity of regulations governing the conduct of clinical trials poses a threat to the very indications for which they are intended. There is an urgent need to review and harmonise the guidelines so that they can be administered in a way that does not compromise the safety and well-being of the trial subjects.