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TB Notes 4, 2004

No. 4, 2004


Updates on the TB Trials Consortium (TBTC)

Enrollment Update: U.S. PHS TBTC Study 27

Enrollment for U.S. Public Health Service (PHS) TBTC Study 27, a double-blind, placebo-controlled comparison of the efficacy and tolerability of moxifloxacin versus ethambutol in the initiation phase of treatment of pulmonary TB, began in July 2003 at North America TBTC sites and in September 2003 at the Kampala, Uganda, site. Initially proposed to study 300 patients and to take 3 years to complete, the pace of enrollments is exceeding expectations. Of the 290 patients thus far enrolled, there has been an equal distribution of enrollments contributed from North America and from the Uganda TBTC sites. The pace of enrollments is expected to accelerate further with the participation of the Durban, South Africa, TBTC site in Study 27, which enrolled its first three patients on July 22, 2004. Because of these developments, it is hoped that enrollment for the entire study will be completed by early- to mid-January 2005 and that preliminary analyses can be completed in time for the May 2005 TBTC and American Thoracic Society (ATS) conferences.

TBTC Study 27 PK

A new substudy of Study 27, “Study 27 PK,” was recently approved by the CDC institutional review board (IRB), and will be carried out at a limited number of TBTC sites. Consisting of two parts, this pharmacokinetic study will (a) compare the concentrations of moxifloxacin among patients receiving multidrug therapy for active TB to those of healthy volunteers; and (b) characterize the inter-patient variation of moxifloxacin pharmacokinetic parameters in patients with TB. Study 27 PK will also evaluate the effect of MDR1 and NAT2 genes on antituberculosis drug pharmacokinetics.

TBTC Study 28

Another new moxifloxacin study on the TBTC horizon is Study 28, which is currently undergoing review by the CDC IRB. The main comparison in Study 28 involves moxifloxacin with isoniazid (rather than ethambutol). Specifically, the primary objective of this Phase II clinical trial is to compare the safety and activity of a moxifloxacin-containing regimen (moxifloxacin, rifampin, pyrazinamide, ethambutol) in which moxifloxacin has been substituted for isoniazid, to the standard control regimen (isoniazid, rifampin, pyrazinamide, ethambutol) in the first 2 months of treatment of sputum smear-positive pulmonary TB. The assessment of microbiological activity will be sputum culture conversion. Improved sputum culture conversion after 2 months of treatment with a moxifloxacin-containing regimen would support phase 3 clinical trials of moxifloxacin in treatment regimens of less than the current 6-month standard regimens. The plan is to enroll 400 patients from both domestic and international TBTC sites.

TBTC Study 26 Update: New Web-Based Enrollment Application

TBTC Study 26 is a trial of short-course treatment of latent TB infection among contacts of active cases, using a 3-month once-weekly regimen of isoniazid and rifapentine, compared to standard 9-month therapy with isoniazid. This flagship TBTC study aims to enroll 7,700 subjects. To date, enrollments have been telephone-based. Recent consortium expansion to international sites, with the associated multiple time zones, makes Web-based enrollment an attractive alternative.

TBTC Study 26 plans to roll out a new Web enrollment application this fall. The Web application was developed as a pilot project through collaboration between DTBE/CHSRB and the Application Development Group, Prevention Informatics Office/NCHSTP.  It will be accessible from any Internet connection and requires a user name and password. Advantages are immediate access for enrollments, increased clinic participation, system availability 24/7, and generation of automatic e-mail notification to sites regarding subject randomization and treatment schedules. 

TBTC Study 26 has already enrolled 3,275 subjects using a Visual Basic/Access application developed in DTBE/CHSRB. Site staff members who call CDC to enroll study subjects occasionally experience delays owing to time zone constraints or when CDC staff are taking other calls. The Web enrollment application will allow real time access for TBTC Study 26 collaborators throughout the United States and in Canada, Brazil, and Spain. Our hope is to increase the pace of enrollments, moving us quickly to our recruitment goal for Study 26.

—Submitted by Phil Spradling, MD
Div of TB Elimination


Released October 2008
Centers for Disease Control and Prevention
National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention
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