title: Safety and efficacy assessment of two new leprosy skin test antigens: randomized double blind clinical study.
abstract: BACKGROUND
  New tools are required for the diagnosis of pre-symptomatic leprosy towards further reduction of disease burden and its associated reactions. To address this need, two new skin test antigens were developed to assess safety and efficacy in human trials.
  
  
  METHODS
  A Phase I safety trial was first conducted in a non-endemic region for leprosy (U.S.A.). Healthy non-exposed subjects (n = 10) received three titrated doses (2.5 µg, 1.0 µg and 0.1 µg) of MLSA-LAM (n = 5) or MLCwA (n = 5) and control antigens [Rees MLSA (1.0 µg) and saline]. A randomized double blind Phase II safety and efficacy trial followed in an endemic region for leprosy (Nepal), but involved only the 1.0 µg (high dose) and 0.1 µg (low dose) of each antigen; Tuberculin PPD served as a control antigen. This Phase II safety and efficacy trial consisted of three Stages: Stage A and B studies were an expansion of Phase I involving 10 and 90 subjects respectively, and Stage C was then conducted in two parts (high dose and low dose), each enrolling 80 participants: 20 borderline lepromatous/lepromatous (BL/LL) leprosy patients, 20 borderline tuberculoid/tuberculoid (BT/TT) leprosy patients, 20 household contacts of leprosy patients (HC), and 20 tuberculosis (TB) patients. The primary outcome measure for the skin test was delayed type hypersensitivity induration.
  
  
  RESULTS
  In the small Phase I safety trial, reactions were primarily against the 2.5 µg dose of both antigens and Rees control antigen, which were then excluded from subsequent studies. In the Phase II, Stage A/B ramped-up safety study, 26% of subjects (13 of 50) showed induration against the high dose of each antigen, and 4% (2 of 50) reacted to the low dose of MLSA-LAM. Phase II, Stage C safety and initial efficacy trial showed that both antigens at the low dose exhibited low sensitivity at 20% and 25% in BT/TT leprosy patients, but high specificity at 100% and 95% compared to TB patients. The high dose of both antigens showed lower specificity (70% and 60%) and sensitivity (10% and 15%). BL/LL leprosy patients were anergic to the leprosy antigens.
  
  
  CONCLUSIONS
  MLSA-LAM and MLCwA at both high (1.0 µg) and low (0.1 µg) doses were found to be safe for use in humans without known exposure to leprosy and in target populations. At a sensitivity rate of 20-25% these antigens are not suitable as a skin test for the detection of the early stages of leprosy infection; however, the degree of specificity is impressive given the presence of cross-reactive antigens in these complex native M. leprae preparations.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT01920750 (Phase I), NCT00128193 (Phase II).
authors.affiliation: Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado, United States of America.
authors.forename: Becky L
authors.initials: BL
authors.lastname: Rivoire
authors.affiliation: Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado, United States of America.
authors.forename: Nathan A
authors.initials: NA
authors.lastname: Groathouse
authors.affiliation: Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado, United States of America.
authors.forename: Stephen
authors.initials: S
authors.lastname: TerLouw
authors.affiliation: Mycobacterial Research Laboratory, Anandaban Hospital, Kathmandu, Nepal.
authors.forename: Kapil Dev
authors.initials: KD
authors.lastname: Neupane
authors.affiliation: Mycobacterial Research Laboratory, Anandaban Hospital, Kathmandu, Nepal.
authors.forename: Chaman
authors.initials: C
authors.lastname: Ranjit
authors.affiliation: Mycobacterial Research Laboratory, Anandaban Hospital, Kathmandu, Nepal.
authors.forename: Bishwa Raj
authors.initials: BR
authors.lastname: Sapkota
authors.affiliation: Mycobacterial Research Laboratory, Anandaban Hospital, Kathmandu, Nepal.
authors.forename: Saraswoti
authors.initials: S
authors.lastname: Khadge
authors.forename: Chhatra B
authors.initials: CB
authors.lastname: Kunwar
authors.affiliation: Mycobacterial Research Laboratory, Anandaban Hospital, Kathmandu, Nepal.
authors.forename: Chatra B
authors.initials: CB
authors.lastname: Kunwar
authors.affiliation: Mycobacterial Research Laboratory, Anandaban Hospital, Kathmandu, Nepal.
authors.forename: Murdo
authors.initials: M
authors.lastname: Macdonald
authors.affiliation: Mycobacterial Research Laboratory, Anandaban Hospital, Kathmandu, Nepal.
authors.forename: Rachel
authors.initials: R
authors.lastname: Hawksworth
authors.affiliation: Mycobacterial Research Laboratory, Anandaban Hospital, Kathmandu, Nepal.
authors.forename: Min B
authors.initials: MB
authors.lastname: Thapa
authors.affiliation: Mycobacterial Research Laboratory, Anandaban Hospital, Kathmandu, Nepal.
authors.forename: Deanna A
authors.initials: DA
authors.lastname: Hagge
authors.affiliation: The EMMES Corporation, Rockville, Maryland, United States of America.
authors.forename: Melinda
authors.initials: M
authors.lastname: Tibbals
authors.affiliation: The EMMES Corporation, Rockville, Maryland, United States of America.
authors.forename: Carol
authors.initials: C
authors.lastname: Smith
authors.affiliation: The EMMES Corporation, Rockville, Maryland, United States of America.
authors.forename: Tina
authors.initials: T
authors.lastname: Dube
authors.affiliation: The EMMES Corporation, Rockville, Maryland, United States of America.
authors.forename: Dewei
authors.initials: D
authors.lastname: She
authors.affiliation: The EMMES Corporation, Rockville, Maryland, United States of America.
authors.forename: Mark
authors.initials: M
authors.lastname: Wolff
authors.affiliation: Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, Maryland, United States of America.
authors.forename: Eric
authors.initials: E
authors.lastname: Zhou
authors.affiliation: Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, Maryland, United States of America.
authors.forename: Mamodikoe
authors.initials: M
authors.lastname: Makhene
authors.affiliation: Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, Maryland, United States of America.
authors.forename: Robin
authors.initials: R
authors.lastname: Mason
authors.affiliation: Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, Maryland, United States of America.
authors.forename: Christine
authors.initials: C
authors.lastname: Sizemore
authors.affiliation: Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado, United States of America.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Brennan
mesh_terms: D000293:Adolescent; D000328:Adult; D000942:Antigens, Bacterial / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007918:Leprosy / Q000175:diagnosis* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009166:Mycobacterium leprae / Q000276:immunology; D012680:Sensitivity and Specificity; D012882:Skin Tests / Q000009:adverse effects* / Q000379:methods*; D055815:Young Adult
chemical_list: D000942:Antigens, Bacterial