Live Attenuated ETEC Vaccine ACE527 With and Without dmLT Adjuvant in Adults

Summary

This is a research study about an experimental (investigational) oral ETEC vaccine (ACE527). ACE527 is a live attenuated vaccine that is being made to prevent disease from enterotoxigenic Escherichia coli (ETEC), which causes watery diarrhea, largely in children living in developing countries and in travelers to those countries. This research study is also testing an investigational adjuvant called dmLT. An adjuvant is something that is added to a vaccine to make it work better. The purpose of this study is two-fold. First, Part A aims to find out if the vaccine by itself or the vaccine combined with the adjuvant is safe, tolerable, and initiates an immune response. Second, Part B aims to find out if the vaccine by itself or the vaccine combined with the adjuvant prevents diarrheal disease when challenged with ETEC H10407. About 60 healthy adults, ages 18-50, will participate in Part A, and they will be required to stay in the research facility for several nights for the first dose, but will not be required to stay overnight for the second and third doses. Participants will be assigned to receive either the vaccine alone, the vaccine with adjuvant, or placebo by mouth. Study procedures include: stool samples, blood samples, and documentation of side effects. Participants will be involved in study related procedures for about 8 months.

Interested volunteers from Part A will along with volunteers who were never vaccinated in Part A will return to participate in Part B. These volunteers will be required to stay overnight in the research facility for several nights after challenge, after which they will be treated with antibiotics and sent home. Study procedures include stool samples, blood samples, and documentation of infection with ETEC H10407. If the vaccine with/without adjuvant is effective, the volunteers should not development diarrhea, but if the vaccine with/without adjuvant is not effective, the volunteers will have diarrhea for a few days.

Conditions

• Diarrhea

Interventions

BIOLOGICAL

ACE527

3x10\^9 cfu ACE527 vaccine strain. Comprised of three genetically attenuated and engineered strains of E. coli, with antigen profiles covering a wide range of ETEC surface colonization factor antigens (CFA/I, CFA/II \[CS1, CS2, CS3\] and CFA/IV \[CS5, CS6\]) and also expressing LTB, the inactive subunit of LT (ETEC heat labile toxin). The constituent strains of ACE527 were: * ACAM2025: a live, attenuated, CFA/I, LTB positive strain * ACAM2022: a live, attenuated, CS5, CS6, LTB positive strain, and * ACAM2027: a live, attenuated, CS1, CS2, CS3, LTB positive strain.

BIOLOGICAL

dmLT

A derivative of wild-type enterotoxigenic Escherichia coli heat-labile enterotoxin that has been genetically modified by replacing the arginine at amino acid position 192 with glycine and the leucine at amino acid position 211 with alanine (13). These two amino acid substitutions take place in proteolytic cleavage sites which are critical for activation of the secreted toxin molecules.

BIOLOGICAL

CeraVacx placebo

CeraVacx® is used to neutralize gastric acidity upon ingestion of vaccine. It was also used as the placebo in this study. CeraVacx® was prepared from the commercial product (Cera Products, Inc.); 9.5 grams were added to sterile water for each dose and mixed. Each dose contained 7 grams of rice syrup, 2 grams of sodium bicarbonate, and 0.5 grams of trisodium citrate.

BIOLOGICAL

H10407 challenge strain

Approximately 2 x 10\^7 cfu of the fully virulent ETEC strain. Previously administered to 91 volunteers at this challenge dose by the CIR clinical team over the previous 4 years in conjunction with other Phase 1/2b trials.

Sponsors & Collaborators

• PATH

  lead OTHER

Principal Investigators

• Clayton D Harro, MD, ScM · Johns Hopkins Bloomberg School of Public Health

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

QUADRUPLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

50 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2012-09-30

Primary Completion

2013-10-31

Completion

2014-01-31

Countries

• United States

Study Locations