TBTC Study 31: Rifapentine-containing Tuberculosis Treatment Shortening Regimens

The purpose of this study is to determine whether one or two four-month regimens of tuberculosis treatment are as effective as a standard six-month regimen for treatment of pulmonary tuberculosis (TB). All three regimens are administered daily, seven days each week, with direct observation of each dose by a health-care worker at least five of the seven days of each week.

The standard six-month regimen is two months of isoniazid, rifampin, ethambutol, and pyrazinamide followed by four months of isoniazid and rifampin.

The first short regimen is a single substitution of rifapentine for rifampin: two months of isoniazid, rifapentine, ethambutol, and pyrazinamide, followed by two months of isoniazid and rifapentine.

The second short regimen is a double substitution of rifapentine for rifampin and moxifloxacin for ethambutol: two months of isoniazid, rifapentine, moxifloxacin, and pyrazinamide, followed by two months of isoniazid, rifapentine, and moxifloxacin.

Target enrollment is 2500 participants. Each study participant will remain in the study for 18 months in order to include at least 12 months of evaluation of whether the participant's TB recurs.

Title:

Rifapentine-containing treatment shortening regimens for pulmonary tuberculosis: a randomized, open-label, controlled, phase 3 clinical trial

Hypotheses:

A) Seventeen (17) week rifapentine-based regimen In previously untreated individuals with active drug-susceptible pulmonary tuberculosis treated with eight weeks of rifapentine (P), isoniazid (H), pyrazinamide (Z) and ethambutol (E) followed by nine weeks of rifapentine plus isoniazid, all given daily throughout, the proportion of participants who experience absence of cure (unfavorable outcome) will not be inferior to that observed in participants who are treated with a standard regimen (eight weeks of rifampin (R), isoniazid, pyrazinamide and ethambutol followed by eighteen weeks of rifampin plus isoniazid), all given daily throughout.

B) Seventeen (17) week rifapentine- plus moxifloxacin-containing regimen In previously untreated individuals with active drug-susceptible pulmonary tuberculosis treated with eight weeks of rifapentine, isoniazid, pyrazinamide and moxifloxacin (M), followed by nine weeks of rifapentine, isoniazid, and moxifloxacin, all given daily throughout, the proportion of participants who experience absence of cure (unfavorable outcome) will not be inferior to that observed in participants who are treated with a standard regimen (eight weeks of rifampin, isoniazid, pyrazinamide and ethambutol followed by eighteen weeks of rifampin plus isoniazid), all given daily throughout.

Phase: 3

Design: This will be an international, multicenter, randomized, controlled, open-label, 3-arm, phase 3 non-inferiority trial.

Population: Patients with newly diagnosed, previously untreated pulmonary tuberculosis.

Number of Sites: Multiple international sites, primarily sites of the Tuberculosis Trials Consortium and the AIDS Clinical Trials Group.

Study Duration: Duration per participant is approximately 18 months.

Description of Agent or Intervention: After written informed consent, participants will be randomly assigned to receive one of the following oral regimens:

Regimen 1 (control regimen): 2RHZE/4RH

* Eight weeks of daily treatment with rifampin, isoniazid, pyrazinamide, and ethambutol, followed by
* Eighteen weeks of daily treatment with rifampin and isoniazid

Regimen 2 (investigational regimen): 2PHZE/2PH

* Eight weeks of daily treatment with rifapentine, isoniazid, pyrazinamide, and ethambutol, followed by
* Nine weeks of daily treatment with rifapentine and isoniazid

Regimen 3 (investigational regimen): 2PHZM/2PHM

* Eight weeks of daily treatment with rifapentine, isoniazid, pyrazinamide, and moxifloxacin, followed by
* Nine weeks of daily treatment with rifapentine, isoniazid, and moxifloxacin

Objectives:

Primary:

* To evaluate the efficacy of a rifapentine-containing regimen to determine whether the single substitution of rifapentine for rifampin makes it possible to reduce to seventeen weeks the duration of treatment for drug-susceptible pulmonary tuberculosis
* To evaluate the efficacy of a rifapentine-containing regimen that in addition substitutes moxifloxacin for ethambutol and continues moxifloxacin during the continuation phase to determine whether it is possible to reduce to seventeen weeks the duration of treatment for drug-susceptible pulmonary tuberculosis

Secondary:

* To evaluate the safety of the investigational regimens
* To evaluate the tolerability of the investigational regimens
* To collect and store biospecimens from consenting participants for the purpose of future research on discovery and validation of TB biomarkers
* To determine the correlation of mycobacterial and clinical markers with time to culture conversion, culture status at completion of eight weeks of treatment, treatment failure, and relapse.
* To conduct a pharmacokinetic/pharmacodynamic (PK/PD) study of the test drugs. The main objectives of the PK/PD study are to characterize study drug PK parameters and to determine relationships between treatment outcomes and PK parameters.
* To evaluate the pharmacokinetics of efavirenz-based antiretroviral treatment among patients with TB/HIV co-infection taking efavirenz-based combination antiretroviral therapy and TB treatment with rifapentine

Endpoints:

Primary Endpoints:

* Efficacy: TB disease-free survival at twelve months after study treatment assignment.
* Safety: Proportion of participants with grade 3 or higher adverse events during study drug treatment

Secondary Endpoints:

* TB disease-free survival at eighteen months after study treatment assignment
* Time to stable sputum culture conversion (solid and liquid media considered separately)
* Speed of decline of sputum viable bacilli by automated liquid MGIT culture days to detection
* Proportion of participants who are culture negative at completion of eight weeks of treatment (solid and liquid media considered separately)
* Sensitivity analyses assuming all participants classified as 'not assessable' have a favorable outcome
* Discontinuation of assigned treatment for a reason other than microbiological ineligibility
* Estimated steady state efavirenz PK parameters including mid-dosing interval concentration

Eligibility Criteria:
Inclusion Criteria:

* Suspected pulmonary tuberculosis plus one or both of the following: a) at least one sputum specimen positive for acid-fast bacilli on smear microscopy OR b) at least one sputum specimen positive for M. tuberculosis by Xpert MTB/RIF testing, with semiquantitative result of 'medium' or 'high' and rifamycin resistance not detected.
* Age twelve (12) years or older
* A verifiable address or residence location that is readily accessible for visiting, and willingness to inform the study team of any change of address during the treatment and follow-up period.
* Women of child-bearing potential who are not surgically sterilized must agree to practice a barrier method of contraception or abstain from heterosexual intercourse during study drug treatment.
* Documentation of HIV infection status.
* For HIV-positive individuals, CD4 T cell count greater than or equal to 100 cells/mm3 based on testing performed at or within 30 days prior to screening.
* Laboratory parameters done at or within 14 days prior to screening:

  * Serum or plasma alanine aminotransferase (ALT) less than or equal to 3 times the upper limit of normal
  * Serum or plasma total bilirubin less than or equal to 2.5 times the upper limit of normal
  * Serum or plasma creatinine level less than or equal to 2 times the upper limit of normal
  * Serum or plasma potassium level greater than or equal to 3.5 meq/L
  * Hemoglobin level of 7.0 g/dL or greater
  * Platelet count of 100,000/mm3 or greater
* For women of childbearing potential, a negative pregnancy test at or within seven (7) days prior to screening
* Karnofsky score greater than or equal to 60
* Written informed consent

Exclusion Criteria:

* Pregnant or breast-feeding.
* Unable to take oral medications.
* Previously enrolled in this study.
* Received any investigational drug in the past 3 months.
* More than five (5) days of treatment directed against active tuberculosis within 6 months preceding initiation of study drugs.
* More than five (5) days of systemic treatment with any one or more of the following drugs within 30 days preceding initiation of study drugs: isoniazid, rifampin, rifabutin, rifapentine, ethambutol, pyrazinamide, kanamycin, amikacin, streptomycin, capreomycin, moxifloxacin, levofloxacin, gatifloxacin, ofloxacin, ciprofloxacin, other fluoroquinolones, ethionamide, prothionamide, cycloserine, terizidone, para-aminosalicylic acid, linezolid, clofazimine, delamanid or bedaquiline.
* Known history of prolonged QT syndrome.
* Suspected or documented tuberculosis involving the central nervous system and/or bones and/or joints, and/or miliary tuberculosis and/or pericardial tuberculosis.
* Current or planned use within six months following enrollment of one or more of the following medications: HIV protease inhibitors, HIV integrase inhibitors, HIV entry and fusion inhibitors, HIV non-nucleoside reverse transcriptase inhibitors other than efavirenz, quinidine, procainamide, amiodarone, sotalol, disopyramide, ziprasidone, or terfenadine. Individuals who are currently taking efavirenz-based antiretroviral treatment or for whom initiation of efavirenz-based antiretroviral treatment is planned within 17 weeks following enrollment may participate.
* Weight less than 40.0 kg.
* Known allergy or intolerance to any of the study medications.
* Individuals will be excluded from enrollment if, at the time of enrollment, their M. tuberculosis isolate is already known to be resistant to any one or more of the following: rifampin, isoniazid, pyrazinamide, ethambutol, or fluoroquinolones.
* Other medical conditions, that, in the investigator's judgment, make study participation not in the individual's best interest.
* Current or planned incarceration or other involuntary detention.