A Phase 1/2 interventional study of Sm-TSP-2/Alhydrogel® vaccine and Sm-TSP-2/Alhydrogel® vaccine plus AP 10-701 in Schistosomiasis and Schistosoma Mansoni, sponsored by Baylor College of Medicine. Completed at 1 site in Uganda. Open to participants aged 18 Years to 45 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-11-04.
Sponsored by Baylor College of Medicine · Phase 1/2, Interventional, and Prevention
The study will recruit up to 290 healthy adult males and non-pregnant females into a two-part clinical trial of a vaccine to protect against schistosomiasis caused by infection with S. mansoni. Two formulations of the Sm-TSP-2 vaccine will be tested: one using Alhydrogel® only, and one using Alhydrogel® plus AP 10-701, each at 3 different doses of antigen: 10mcg, 30mcg, and 100mcg.
The first part of the study will be a Phase I dose-escalation safety and immunogenicity study followed by a Phase IIb trial in which a larger number of adults will be enrolled to assess the impact of the vaccine on infection with S. mansoni. The impact of the vaccine on infection with S. haematobium will also be assessed although this will be exploratory given that potential cross-protection against this species is only hypothetical at this point.
The study will recruit up to 290 healthy adult males and non-pregnant females into a two-part clinical trial of a vaccine to protect against schistosomiasis caused by infection with S. mansoni. Two formulations of the Sm-TSP-2 vaccine will be tested: one using Alhydrogel® only, and one using Alhydrogel® plus AP 10-701, each at 3 different doses of antigen: 10mcg, 30mcg, and 100mcg.
The first part of the study will be a Phase I dose-escalation safety and immunogenicity study followed by a Phase IIb trial in which a larger number of adults will be enrolled to assess the impact of the vaccine on infection with S. mansoni. The impact of the vaccine on infection with S. haematobium will also be assessed although this will be exploratory given that potential cross-protection against this species is only hypothetical at this point.
Part A: double blind (within cohort), randomized, controlled, dose-escalation Phase 1b clinical trial in S. mansoni exposed adults living in the area of Kampala, Uganda. In each of 3 cohorts, subjects will be randomly assigned to 1 of 3 groups: Sm-TSP-2/Alhydrogel®, Sm-TSP-2/Alhydrogel®/AP 10-701, or the licensed Hepatitis B vaccine (up to 12 subjects per study vaccine group and 6 subjects in the Hepatitis B vaccine group). Subjects will receive three doses of the assigned vaccine delivered intramuscularly at approximately Days 0, 56, and 112.
Safety will be measured from the time of each study vaccination (Days 0, 56, 112 [Visits 2, 7, 12]) through 7 days after each study vaccination by the occurrence of solicited injection site and systemic reactogenicity events. Unsolicited non-serious adverse events (AEs) will be collected from the time of each study vaccination through approximately 28 days after each study vaccination. New-onset chronic medical conditions (including adverse events of special interest [AESI]) and serious adverse events (SAEs) will be collected from the time of the first study vaccination (Day 0 [Visit 2]) through approximately 9 months after the third study vaccination (Day 380 [Visit 19]). Clinical laboratory evaluations for safety will be performed on venous blood collected approximately 7 days after each study vaccination.
Immunogenicity testing will include IgG antibody responses to Sm-TSP-2 by a qualified indirect ELISA on serum obtained prior to each study vaccination (Days 0, 56, 112) and at time points after each vaccination.
Ninety subjects will be enrolled into 3 groups of 30. Recruitment and enrollment into the study will occur on an ongoing basis, with each group being recruited and vaccinated in sequence.
Part A of the study is a dose escalation trial in which escalation to the next dose cohort will be determined based on evaluation of pre-defined escalation criteria, which will be evaluated 7 days after all subjects in the currently active cohort have received their first dose of vaccine. Within each cohort, the assignment to Alhydrogel®, Alhydrogel®/AP 10-701, or Hepatitis B vaccine will be randomized and double-blinded (i.e., neither the subject nor the investigator will be aware of the formulation assigned). The study will proceed as follows:
Cohort 1, N=30 [10mcg Sm-TSP-2/Alhydrogel® (n=12) or 10mcg Sm-TSP-2/Alhydrogel®/ AP 10-701 (n=12) or Hepatitis B vaccine (n=6)]
Cohort 2, N=30 [30mcg Sm-TSP-2/Alhydrogel® (n=12) or 30mcg Sm-TSP-2/Alhydrogel®/AP 10-701 (n=12) or Hepatitis B vaccine (n=6)]
Cohort 3, N=30 [100mcg Sm-TSP-2/Alhydrogel® (n=12) or 100mcg Sm-TSP-2/Alhydrogel®/AP 10-701 (n=12) or Hepatitis B vaccine (n=6)]
Part B: double blind, randomized, controlled, dose-escalation Phase IIb clinical trial in adults living in the area of Kampala, Uganda, who reside in S. mansoni endemic areas with greater than or equal to 25% prevalence in children aged 5-15 years of age. In this part of the study, up to 200 eligible Schistosoma-positive (by Kato Katz fecal thick smear or CAA) adult volunteers will be progressively enrolled and randomized to receive either Sm-TSP-2/Alhydrogel® (with or without AP 10-701) or the Hepatitis B comparator vaccine, in a 1:1 fashion. The dose and formulation (i.e., with or without the point-of-injection addition of AP 10-701) of Sm-TSP-2/Alhydrogel® that will be tested in this part of the study will be chosen based on the interim results of Part A of the trial after all participants have received their third dose of vaccine. All participants in Part B will be treated with praziquantel prior to receipt of the first vaccination.
Interim safety and anti-Sm-TSP-2 IgG antibody results up to and including Day 126 of Part A of the trial will be evaluated to determine the dose that will be tested in Part B.
Two hundred subjects will be enrolled in Part B. The 12 subjects in Part A who received the same dose/formulation of Sm-TSP-2/Alhydrogel® that is chosen for Part B will be offered the opportunity to transition to Part B for the remainder of their participation in the study.
Recruitment and enrollment into the study will occur on an ongoing basis, with participants being recruited, randomized and vaccinated in sequence. Within Part B, the assignment to Sm-TSP-2/Alhydrogel® or Hepatitis B vaccine will be randomized and double-blinded (i.e., neither the subject nor the investigator will be aware of the formulation assigned). Part B of the study will proceed as follows:
1. Cohort 4, N=200 [Sm-TSP-2/Alhydrogel® [dose and formulation TBD] (n=100) or Hepatitis B vaccine (n=100)]
Subjects will receive three doses of the assigned vaccine delivered intramuscularly at approximately Days 0, 56, and 112.
Safety will be measured from the time of each study vaccination (Days 0, 56, 112 [Visits 2, 7, 12]) through 7 days after each study vaccination by the occurrence of solicited injection site and systemic reactogenicity events. Unsolicited non-serious adverse events (AEs) will be collected from the time of each study vaccination through approximately 28 days after each study vaccination. New-onset chronic medical conditions (including adverse events of special interest [AESI]) and serious adverse events (SAEs) will be collected from the time of the first study vaccination (Day 0 [Visit 2]) through approximately 23 months after the third study vaccination (Day 800 [Visit 21]). Clinical laboratory evaluations for safety will be performed on venous blood collected approximately 7 days after each study vaccination.
Immunogenicity testing will include IgG antibody responses to Sm-TSP-2 by a qualified indirect ELISA on serum obtained prior to each study vaccination (Days 0, 56, 112) and at time points after each vaccination.
Efficacy will be evaluated by measuring the impact of vaccination with Sm-TSP-2/Alhydrogel® on fecal and urine Schistosoma egg counts and CAA positivity. After final vaccination, fecal and urine samples will be collected at 12 and 23 months following the final vaccination to determine rates and intensities of re-infection. The primary endpoint to determine the impact of vaccination on infection with S. mansoni will be incidence of infection as determined by a positive CAA test or Kato-Katz fecal thick smear. The impact of vaccination on infection with S. haematobium will be assessed as an exploratory endpoint, by means of urine microscopy for schistosome eggs.
79 studies on the registry are indexed under Schistosomiasis; 14 are open to participants now.
This study's enrollment of 290 is close to the median of 289 across 52 interventional studies indexed under Schistosomiasis.
Browse Schistosomiasis studies →Baylor College of Medicine is the lead sponsor of 747 studies on the registry; 110 are open to participants now.
Of its 84 completed or terminated interventional studies of FDA-regulated products, 45 (54%) have results posted.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Anti-Sm-TSP-2 IgE antibody level above ELISA reactivity threshold.
Part A Only:
Positive confirmatory test for virus (HCV) infection.
Part B Only:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Vaccines made with a weakened form of the germ, such as measles–mumps–rubella (MMR), chickenpox and yellow fever. They can be risky when the immune system is weakened. Flu injections are not live; the nasal flu spray is.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Autoimmune disease
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Live vaccines
Vaccines made with a weakened form of the germ, such as measles–mumps–rubella (MMR), chickenpox and yellow fever. They can be risky when the immune system is weakened. Flu injections are not live; the nasal flu spray is.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Sm-TSP-2/Alhydrogel Schistosomiasis Vaccine, delivered by IM injection on study days 0, 56, and 12; 10 mcg dose
Biological: Sm-TSP-2/Alhydrogel® vaccine
Sm-TSP-2/Alhydrogel Schistosomiasis Vaccine plus AP 10-701, delivered by IM injection on study days 0, 56, and 12; 10 mcg dose
Biological: Sm-TSP-2/Alhydrogel® vaccine plus AP 10-701
Sm-TSP-2/Alhydrogel Schistosomiasis Vaccine, delivered by IM injection on study days 0, 56, and 12; 30 mcg dose
Biological: Sm-TSP-2/Alhydrogel® vaccine
Sm-TSP-2/Alhydrogel Schistosomiasis Vaccine plus AP 10-701, delivered by IM injection on study days 0, 56, and 12; 30 mcg dose
Biological: Sm-TSP-2/Alhydrogel® vaccine plus AP 10-701
Sm-TSP-2/Alhydrogel Schistosomiasis Vaccine, delivered by IM injection on study days 0, 56, and 12; 100 mcg dose
Biological: Sm-TSP-2/Alhydrogel® vaccine
Sm-TSP-2/Alhydrogel Schistosomiasis Vaccine plus AP 10-701, delivered by IM injection on study days 0, 56, and 12; 100 mcg dose
Biological: Sm-TSP-2/Alhydrogel® vaccine plus AP 10-701
Hepatitis B Vaccine
Biological: ENGERIX-B Hepatitis B Vaccine
Sm-TSP-2/Alhydrogel Schistosomiasis Vaccine, with or without AP 10-701, dose and formulation determined in Part A
Biological: Sm-TSP-2/Alhydrogel® vaccine
Hepatitis B Vaccine
Biological: ENGERIX-B Hepatitis B Vaccine
The Sm-TSP-2/Alhydrogel® candidate vaccine contains recombinant Sm-TSP-2 adsorbed onto aluminum hydroxide gel (Alhydrogel®) and suspended in a solution containing 10mM imidazole buffer containing 2mM phosphate and 15% sucrose, with pH 7.4 ± 0.1. The final concentrations of Sm-TSP-2 and Alhydrogel® in the drug product are 0.1mg/ml and 0.8mg/ml respectively.
The Sm-TSP-2/Alhydrogel® candidate vaccine co-administered with the immunostimulant, AP 10-701. b) AP 10-701, also known as Gluco-Pyranosylphospho-Lipid A Aqueous Formulation (GLA-AF), is a Toll-like Receptor-4 agonist. Point-of-injection formulations with this immunostimulant will be prepared immediately prior to vaccination by adding an appropriate volume of AP 10-701 to Sm-TSP-2/Alhydrogel® and withdrawing an appropriate volume to administer the desired amount of Sm-TSP-2 plus 5µg GLA-AF.
Recombinant hepatitis B vaccine containing 10 mcg recombinant hepatitis B surface antigen per dose
Safety and Tolerability: frequency of local and systemic reactogenicity events
Frequency of solicited injection site and systemic reactogenicity, graded by severity, on the day of each study vaccination through 7 days after each study vaccination.
Time frame: 7 days post-vaccination
Safety and Tolerability: frequency of unsolicited adverse events
Frequency of unsolicited adverse events, graded by severity, from the time of each study vaccination through approximately 1 month after each study vaccination.
Time frame: 28 days post-vaccination
Safety and Tolerability: frequency of vaccine-related Serious Adverse Events
Frequency of study vaccine-related Serious Adverse Events from the time of the first study vaccination through the final study visit.
Time frame: 23 months
Safety and Tolerability: frequency of clinical safety laboratory adverse events
Frequency of clinical safety laboratory adverse events measured 7 days after each vaccination
Time frame: 7 days post-vaccination
Safety and Tolerability: frequency of new-onset chronic medical conditions
Frequency of new-onset chronic medical conditions, including Adverse Events of Special Interest, through the final study visit
Time frame: 23 months
Efficacy: proportion of subjects with detectable S. mansoni eggs
Proportion of subjects with detectable S. mansoni eggs at 12 and 23 months in fecal samples, as determined by Kato Katz fecal thick smear.
Time frame: 12 and 23 months
Efficacy: mean S. mansoni eggs per gram of feces
Mean S. mansoni eggs per gram as determined by fecal microscopy (Kato Katz fecal thick smear) at 12 and 23 months.
Time frame: 12 and 23 months
Efficacy: Proportion of subjects with a positive CAA test
Proportion of subjects with a positive CAA test at 12 and 23 months.
Time frame: 12 and 23 months
Immunogenicity: peak anti-Sm-TSP-2 IgG level
IgG level by qualified indirect ELISA on approximately Day 126
Time frame: Day 126
Immunogenicity: anti-Sm-TSP-2 IgG levels over time
IgG antibody response measured by qualified indirect ELISA
Time frame: Approximately 14 days after doses one and two and at Days 200, 290, 380 (Parts A and B) after final dose, and at Days 548, and 800 (Part B) after final dose.
Efficacy: CAA (Part B only)
Proportion of subjects with a positive CAA test
Time frame: 12 and 23 months following final vaccination
Efficacy: fecal Schistosomal DNA
Levels of Schistosoma DNA in fecal samples, as measured by real-time PCR.
Time frame: 12 and 23 months following final vaccination
Plan to share: Yes — De-identified individual participant data related to primary and secondary objectives will be made available within 12 months of finalization of the Clinical Study Report.
Time frame: Within 12 months of finalization of the Clinical Study Report.
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