Clinical Trial: Comparison of Three Plasmodium Falciparum Isolates in a Controlled Human Malaria Infection

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title: Comparison of NF54, NF135 and NF166 Strains of Plasmodium Falciparum in a Controlled Human Malaria Infection (TIP3)

Brief Summary:

An effective vaccine against malaria is urgently needed to combat the scourge of this disease. Before candidate vaccines can be tested in endemic countries, they are first tested in human volunteers in so-called Controlled Human Malaria Infections (CHMI's). Ideally, a candidate vaccine should be tested against multiple strains of malaria, representative of the disease's global distribution. To date, however, only one such strain (NF54) has been broadly used in CHMI's.

The purpose of this study is to compare the course of infections with 2 novel malaria strains to those with NF54 in human volunteers.


Detailed Summary:

Plasmodium falciparum (Pf) malaria remains responsible for an intolerable burden of morbidity worldwide and an effective vaccine is sorely needed to aid control efforts. Before candidate malaria vaccines can enter full-scale (phase IIb) field trials in endemic areas, they must first be tested under controlled circumstances in (phase IIa) clinical human malaria infection studies. Since Pf isolates display a wide genetic diversity across the globe, phase IIa challenge infections should be conducted with both homologous and heterologous strains.

Since 1998 a highly successful Controlled Human Malaria Infection model at the UMC St Radboud, Nijmegen, The Netherlands, has been employed both to test candidate vaccines and to answer fundamental questions about pathophysiological and immunological mechanisms during early Pf infection in human volunteers. To date largely the NF54 strain of P. falciparum has been used in this Nijmegen model, with which extensive experience has meanwhile been acquired. In order to increase the portfolio of Pf strains available for future phase IIa studies, it is first necessary to document in detail the parasitological, clinical and immunological characteristics of new candidate strains during a controlled human malaria infection. In this study, the strains NF135 and NF166 will be compared in this regard with the well-characterised NF54 strain.


Sponsor: Radboud University

Current Primary Outcome: Difference in kinetics of infection between groups infected with NF54, NF133 and NF166, as defined by a mathematical model that takes into account multiple measurements of parasitaemia [ Time Frame: between day 5 and day 21 ]

Parasitaemia will be measured retrospectively by QRT-PCR in twice daily drawn venous whole blood, from day 5 post-infection until day of thick smear positivity, or else until day 21 post-infection if volunteers have not yet developed a positive thick smear before then. All these data points will be fed into a mathematical model that amalgamates them to calculate an outcome variable with one single value for burden of (liver-stage) infection and one for (blood-stage) multiplication factor.


Original Primary Outcome: Difference in kinetics of infection between groups infected with NF54, NF133 and NF166, as defined by a mathematical model that takes into account multipe measurements of parasitaemia [ Time Frame: between day 5 and day 21 ]

Parasitaemia will be measured retrospectively by QRT-PCR in twice daily drawn venous whole blood, from day 5 post-infection until day of thick smear positivity, or else until day 21 post-infection if volunteers have not yet developed a positive thick smear before then. All these data points will be fed into a mathematical model that amalgamates them to calculate an outcome variable with one single value for burden of (liver-stage) infection and one for (blood-stage) multiplication factor.


Current Secondary Outcome:

  • Difference in time till thick smear positivity between groups infected with NF54, NF135 and NF166 [ Time Frame: between day 5 and day 21 ]
    Thick smears will be read twice daily from day 5 post-infection until day of thick smear positivity, or else until day 21 post-infection
  • Difference in duration or peak height of parasitaemia between groups infected with NF54, NF135 and NF166 [ Time Frame: between day 5 and day 21 ]
    Parasitaemia will be measured retrospectively by QRT-PCR in twice daily drawn venous whole blood, from day 5 post-infection until day of thick smear positivity, or else until day 21 post-infection.
  • Difference in frequency of malaria-related symptoms and signs between groups infected with NF54, NF135 and NF166 [ Time Frame: between day 5 and day 35 ]
    Symptoms and signs will be assessed at twice daily check-up visits from day 5 post-infection until three days after thick smear positivity, or else until day 24 post-infection, and then again on day 35-post infection.
  • Difference in induced immunological responses between groups infection with NF54, NF135 and NF166 [ Time Frame: between day -1 and day 35 ]
    Peripheral venous whole blood will be drawn for assessment of serological and cellular immune responses on day 1-prior to infection, day 5 post-infection, day 9 post-infection and day 35 post-infection.


Original Secondary Outcome: Same as current

Information By: Radboud University

Dates:
Date Received: May 25, 2012
Date Started: August 2012
Date Completion:
Last Updated: November 26, 2012
Last Verified: November 2012