DAR-901 vaccine for the prevention of infection with Mycobacterium tuberculosis among BCG-immunized adolescents in Tanzania: A randomized controlled, double-blind phase 2b trial.

BACKGROUND: SRL172 prevented disease due to Mycobacterium tuberculosis in a Phase 3 trial. DAR-901 represents a scalable manufacturing process for SRL172. We sought to determine if DAR-901 would prevent infection with M. tuberculosis among BCG-primed adolescents age 13-15 years in Tanzania. METHODS: Adolescents with a negative T- SPOT.TBR interferon gamma release assay (IGRA) were randomized 1:1 to three intradermal injections of DAR-901 or saline placebo at 0, 2 and 4 months. Repeat IGRAs were performed at 2 months, and at 1, 2, and 3 years. The primary efficacy outcome was time to new TB infection (IGRA conversion to positive); the secondary outcome was time to persistent TB infection (IGRA conversion with repeat positive IGRA). RESULTS: Among 936 participants screened 667 were eligible and randomized to their first dose of vaccine or placebo (safety cohort). At 2 months, 625 participants remained IGRA-negative and were scheduled for the additional two doses (efficacy cohort). DAR-901 was safe and well-tolerated. One DAR-901 recipient developed a vaccine site abscess. Neither the primary nor secondary endpoints differed between the two treatment arms (p = 0.90 and p = 0.20, respectively). DAR-901 IGRA converters had median responses to ESAT-6 of 50.1 spot-forming cells (SFCs) vs. 19.6 SFCs in placebo IGRA converters (p = 0.03). CONCLUSIONS: A three-dose series of 1 mg DAR-901 was safe and well-tolerated but did not prevent initial or persistent IGRA conversion. DAR-901 recipients with IGRA conversion demonstrated enhanced immune responses to ESAT-6. Since protection against disease may require different immunologic responses than protection against infection a trial of DAR-901 to prevent TB disease is warranted. TRIAL REGISTRATION: The trial is registered at ClinicalTrials.gov as NCT02712424.

Basis for treatment of tuberculosis among HIV-infected patients in Tanzania: the role of chest x-ray and sputum culture.

BACKGROUND: Active tuberculosis (TB) is common among HIV-infected persons living in tuberculosis endemic countries, and screening for tuberculosis (TB) is recommended routinely. We sought to determine the role of chest x-ray and sputum culture in the decision to treat for presumptive TB using active case finding in a large cohort of HIV-infected patients. METHODS: Ambulatory HIV-positive subjects with CD4 counts > or = 200/mm3 entering a Phase III TB vaccine study in Tanzania were screened for TB with a physical examination, standard interview, CD4 count, chest x-ray (CXR), blood culture for TB, and three sputum samples for acid fast bacillus (AFB) smear and culture. RESULTS: Among 1176 subjects 136 (12%) were treated for presumptive TB. These patients were more frequently male than those without treatment (34% vs. 25%, respectively; p = 0.049) and had lower median CD4 counts (319/microL vs. 425/microL, respectively; p < .0001). Among the 136 patients treated for TB, 38 (28%) had microbiologic confirmation, including 13 (10%) who had a normal CXR and no symptoms. There were 58 (43%) treated patients in whom the only positive finding was an abnormal CXR. Blood cultures were negative in all patients. CONCLUSION: Many ambulatory HIV-infected patients with CD4 counts > or = 200/mm3 are treated for presumptive TB. Our data suggest that optimal detection requires comprehensive evaluation, including CXR and sputum culture on both symptomatic and asymptomatic subjects.

Pre- and post-natal macronutrient supplementation for HIV-positive women in Tanzania: Effects on infant birth weight and HIV transmission.

OBJECTIVE: To determine if a protein-calorie supplement (PCS) plus a micronutrient supplement (MNS) improves outcomes for HIV-infected lactating women and their infants. DESIGN: Randomized, controlled trial. SETTING: Dar es Salaam, Tanzania. SUBJECTS, PARTICIPANTS: Pregnant HIV-infected women enrolled in PMTCT programs who intended to breastfeed for 6 months. INTERVENTION: Randomization 1:1 to administration of a PCS plus MNS versus MNS alone among 96 eligible women beginning in the third trimester and continuing for 6 months of breast-feeding. MAIN OUTCOME MEASURE(S): Primary: infant weight at 3 months. Secondary: maternal BMI at 6 months. RESULTS: PCS resulted in significant increases in daily energy intake compared to MNS at all time points (range of differences: +388-719 Kcal); and increases in daily protein intake (range of differences: +22-33 gm). Infant birth weight (excluding twins) was higher in the PCS than MNS groups: 3.30 kg vs 3.04 kg (p = 0.04). Infant weight at 3 months did not differ between PCS and MNS groups: 5.63 kg vs 5.99 kg (p = 0.07). Maternal BMI at 6 months did not differ between PCS and MNS groups: 24.3 vs 23.8 kg/m2 (p = 0.68). HIV transmission occurred in 0 infants in the PCS group vs 4 in the MNS group (p = 0.03). CONCLUSIONS: In comparison to MNS the PCS + MNS intervention was well tolerated, increased maternal energy and protein intake, and increased infant birth weight, but not weight at 3 months or maternal BMI at 6 months. Reduced infant HIV transmission in the PCS + MNS group was observed. TRIAL REGISTRATION: Clinical Trials.Gov NCT01461863.

High rates of clinical and subclinical tuberculosis among HIV-infected ambulatory subjects in Tanzania.

BACKGROUND: We sought to determine the prevalence of active tuberculosis among ambulatory HIV-infected persons in Tanzania with CD4 cell counts of > or =200 cells/mm3 and a bacille Calmette-Guerin vaccination scar. METHODS: Subjects who volunteered for a tuberculosis booster vaccine trial were screened for active tuberculosis by obtainment of a history, physical examination, chest radiography, sputum culture and acid fast bacillus (AFB) stain, and blood culture. All subjects underwent a tuberculin skin test (TST) and lymphocyte proliferation assays (LPAs) for detection of responses to mycobacterial antigens. RESULTS: Active tuberculosis was identified at baseline in 14 (15%) of the first 93 subjects who were enrolled: 10 (71%) had clinical tuberculosis (symptoms or chest radiograph findings), and 4 (29%) had subclinical tuberculosis (positive sputum AFB stain or culture results but no symptoms or chest radiograph findings). An additional 6 subjects with subclinical tuberculosis were identified subsequently. The 10 subjects with subclinical tuberculosis included 3 with positive sputum AFB stains results and 7 who were only identified by a positive sputum culture result. Compared with subjects who did not have tuberculosis, the 10 subjects with subclinical tuberculosis were more likely to have peripheral lymphadenopathy, positive TST results, and elevated LPA responses to early secreted antigenic target-6 (ESAT). Eight of 10 patients had received isoniazid because of a positive TST result before active tuberculosis was recognized. CONCLUSIONS: Clinical and subclinical tuberculosis are common among ambulatory HIV-infected persons, and some cases can only be identified by sputum culture. World Health Organization guidelines for screening for latent tuberculosis before treatment do not recommend sputum culture and, therefore, may fail to identify a substantial number of HIV-infected persons with subclinical, active tuberculosis.

Immunogenicity of an inactivated mycobacterial vaccine for the prevention of HIV-associated tuberculosis: a randomized, controlled trial.

OBJECTIVE: Prior to the widespread use of Mycobacterium bovis, Bacille Calmette-Guerin (BCG), inactivated whole cell mycobacterial vaccines had been shown effective in the prevention of tuberculosis. The present study was conducted to determine the safety and immunogenicity of an inactivated whole cell mycobacterial vaccine in persons with HIV infection.DESIGN Randomized, controlled trial. METHODS: A total of 39 HIV-positive patients with prior BCG immunization and CD4 cell counts >/= 200 x 10(6) cells/l were randomized to five doses of inactivated Mycobacterium vaccae (MV) vaccine or control vaccine (CV). Lymphocyte proliferation (LPA) and interferon gamma (IFN-gamma) responses to mycobacterial antigens were assayed at baseline, after three and five doses of vaccine and > 1 year later. Parallel studies were conducted in 10 HIV-negative subjects with prior BCG immunization. RESULTS: Among HIV-positive patients, 19 MV recipients had higher LPA and IFN-gamma responses to MV sonicate than 20 CV recipients after three and five doses of vaccine and > 1 year later. LPA responses to Mycobacterium tuberculosis whole cell lysate increased over time in both groups consistent with prior BCG immunization and current antiretroviral therapy; after three doses, responses were boosted to higher levels in MV subjects than CV subjects. LPA responses to WCL were also boosted in HIV-negative MV recipients. Immunization was safe and had no adverse effects on HIV viral load or CD4 cell count. CONCLUSIONS: In BCG-primed, HIV-positive and HIV-negative subjects, MV induces durable cellular immune responses to a new mycobacterial antigen and boosts pre-existing responses to WCL. MV is a candidate for clinical trials for the prevention of HIV-associated tuberculosis.

Prevention of tuberculosis in Bacille Calmette-Guérin-primed, HIV-infected adults boosted with an inactivated whole-cell mycobacterial vaccine.

OBJECTIVE: To determine whether a multiple-dose series of an inactivated whole cell mycobacterial vaccine, Mycobacterium vaccae, can prevent HIV-associated tuberculosis. DESIGN AND METHODS: The DarDar trial was a randomized, placebo-controlled, double-blind trial. The study was carried in an outpatient facility in Dar es Salaam, Tanzania. HIV-infected patients with CD4 cell counts of at least 200 cells/microl and a Bacille Calmette-Guérin scar were chosen for the study. The intervention was carried out by random 1:1 assignment to five intradermal doses of M. vaccae or placebo. Tuberculin skin tests were performed, and patients with reactions of at least 5 mm were administered isoniazid for 6 months. The main outcome measures were disseminated (primary endpoint), definite, and probable tuberculosis (secondary endpoints). RESULTS: Two thousand thirteen individuals were randomized (1006 to M. vaccae, 1007 to placebo) and followed every 3 months for a median of 3.3 years. The trial was terminated early because of slow accrual of cases of disseminated tuberculosis and significant protection against definite tuberculosis. Hazard ratios were disseminated tuberculosis 0.52 (95% confidence interval 0.21-1.34; seven cases in M. vaccae, 13 cases in placebo; log-rank P = 0.16), definite tuberculosis 0.61 (95% confidence interval 0.39-0.96; 33 cases in M. vaccae, 52 cases in placebo; P = 0.03), and probable tuberculosis 1.17 (95% confidence interval 0.76-1.80; 48 cases in M. vaccae, 40 cases in placebo; P = 0.46). Immunization was well tolerated, with no adverse effect on CD4 cell count or HIV viral load, and no increase in the rate of serious adverse events. CONCLUSION: Administration of a multiple-dose series of M. vaccae to HIV-infected adults with childhood Bacille Calmette-Guérin immunization is safe and is associated with significant protection against definite tuberculosis. These results provide evidence that immunization with a whole cell mycobacterial vaccine is a viable strategy for the prevention of HIV-associated tuberculosis.