Community Research and Development Information Service - CORDIS

Periodic Report Summary 3 - MULEVACLIN (Clinical Studies on a Multivalent Vaccine for Human Visceral Leishmaniasis)

Project Context and Objectives:
Leishmaniasis was declared as one of the world’s most neglected diseases at the 60th WHO Assembly. Leishmaniasis can be manifested as a wide range of clinical etiologies including visceral, mucocutaneous, diffuse, and cutaneous leishmaniasis (CL). Visceral leishmanasis (VL), the most severe form of the disease, can be fatal if left untreated. The devastating effects of this disease affect largely the poorest of the poor, mainly in developing countries with a disease burden calculated at 2 090 000 disability adjusted life years. Environmental changes have also led to leishmaniasis outbreaks spreading to parts of southern Europe.
Existing treatments for this neglected disease have severe drawbacks. Attempts at vector control policies have been shown to be insufficient, impractical, or difficult to sustain. To date there is no effective vaccine against human leishmaniasis. Although several attempts to develop candidate vaccines against leishmaniasis very few candidates progressed beyond the preclinical evaluation.
We believe that the natural infection cycle of Leishmania should be taken into account in order to generate a vaccine with the potential to efficiently block vector transmission and infection of the human host. Hence, our approach is based on the use of a protein (LJL143) present in the sand fly saliva, together with four Leishmania infantum antigens: Kinetoplastid membrane protein-11 (KMP-11), sterol 24-c-methyltransferase (SMT), nucleoside hydrolase (NH) and cysteine protease b (CPB). All the antigens are produced as recombinant proteins, three of them forming a fusion protein called LEISH-F3+ (or NH/SMT/ΔCPB). Another component included in the vaccine composition is the Glucopyranosyl lipid A (GLA), a well-characterized adjuvant, yet tested in clinical studies, that potentiates Th1 responses. This adjuvant is formulated in a squalene-based oil-in-water emulsion (SE). Additionally, because recombinant proteins alone, as well as peptides, generally induce only weak T cell responses, to facilitate antigen-presentation to immune cells and, therefore, to enhance the immunological response against the target antigens, recombinant proteins are being formulated into virus-like particles (VLP) based on the proven Virosome technology. The partners and the network created around this EU funded project represent some of the world leading experts in each of the research areas needed for generating and testing this candidate vaccine in clinical trials; all of them at the forefront of research into leishmaniasis. This proposal, Clinical Studies on a Multivalent Vaccine for Human Visceral Leishmaniasis (MuLeVaClin), represents an innovative approach in combining proven technologies and the latest insights on leishmaniasis in order to produce an efficacious vaccine. The purpose of MuLeVaClin is to deliver the most advanced vaccine against human leishmaniasis as shown by clinical trials (phase I/II) confirming the safety and immunogenicity of the candidate vaccine.
To achieve this goal, the MuLeVaClin project aims to the following specific objectives:
1. To test an innovative vaccine for human visceral leishmaniasis based on multivalent VLP adjuvanted with a strong TLR4 agonist, containing the recombinant insect salivary gland protein LJL143, the Leishmania promastigote protein KMP11, and the recombinant fusion protein LEISH-F3+, consisting of Leishmania antigens (sterol 24-c-methyltransferase, nucleoside hydrolase and a truncated version of cysteine protease b).
2. The optimal composition of the vaccine formulation and the immune response elicited will be evaluated in preclinical studies in mice, hamsters and dogs. In addition, the immunogenicity of the different proteins will be analysed in asymptomatic and VL cured individuals.
3. To develop a highly stable vaccine to facilitate storage and transportation, suitable for sub-tropical and tropical regions.
4. To establish GMP production technologies for each component and formulation of the vaccine.
5. To evaluate preclinical safety (toxicology studies) in suitable animal models, which will analysed under the scrutiny of the Swiss regulatory authorities.
6. To develop specific tools and quantitative procedures to evaluate biomarkers of resistance and susceptibility in individuals from endemic areas, and the strength of the immune response in those enrolled in clinical trials
7. To prepare and submit an IND dossier to the Swiss regulatory authority.
8. To perform phase I/II clinical trials to investigate safety, optimal human dose and regimen and to analyse the immune-response generated after vaccination.
Project Results:
The production of the different antigens, adjuvants and final formulation of the vaccine are carried out to provide enough amounts of the formulated vaccine and its individualized components to assess the efficacy of the vaccine in mouse, hamster and dog model. The studies conducted in mouse model has shown that both vaccine formulations (antigens combined with GLA-SE and VLP-formulated antigens + GLA-SE) are similarly immunogenic, and, therefore, both vaccines may be suitable for further analysis. Results obtained in hamster model confirmed the high immunogenicity of the complete vaccine formulation (adjuvant + virosome + proteins) in terms of humoral response, inducing antibody production after immunization and experimental challenge, as well as in terms of reduction of the parasite burden in target organs, reduction that was significant in the case of the adjvated virosomal formulation VPA 5:5:1. The optimised formulation is now being tested in dog trial. Even though the dog trial is still ongoing, the preliminary results are promising. The unforeseen problems for immunogenicity arose during the past reporting periods were properly addressed and sorted out and within this reporting period final efforts have been dedicated to standardize the procedure for production and to assess the production consistency across different batches for KMP11, LJL143 and LeishF3+ antigens and virosomal formulations. All the analytical methods to characterize the vaccine formulation and individual antigens content are set up validated and ready to be applied in GMP vaccine batches. Highly stable vaccine formulation suitable for transportation and storage in sub-tropical and tropical regions have been further developed and process for the GMP production for each antigen (KMP11, LJL143, LeishF3+) and adjuvant (GLA-SE) component of the vaccine and for the final vaccine formulation are finalized. Long-term stability study will run in parallel with toxicological study.
In order to be well prepared for the clinical evaluation of the candidate vaccine, during this reporting period the development of quantitative assays to determine levels of immunity and to distinguish vaccinated individuals from cured VL patients and asymptomatic subjects have been set up. Since no vaccinated individual are available, these assays has been done by testing cell and humoral responses in individuals with Leishmania-specific immunity like asymptomatic and VL cured patients. Indeed, as the nature of the specific protection against the parasite is cell mediated, quantitative assessment of immunity induced by the vaccine must be based in a cellular test, while the test to distinguish vaccinated from asymptomatic/cured individuals should be based in the different humoral response elicited by the vaccine or by natural infection. The results achieved so far achieved led to the identification of rK28 as the best antigens to establish a test to identify asymptomatic individuals. Further, studies on specific cell response to the vaccine antigens confirmed that expression of IFNγ after stimulation of lymphocytes is a good marker of immunity that could be used to establish the test to distinguish vaccinated from asymptomatic individuals. Noteworthy, the assays so far developed and the results achieved can be applied also to analyse the canine samples obtained in dog trial.
With reference to the clinical trial, the orphan disease status as an important medicinal product for the rare disease “prophylaxis of leishmaniasis at high risk of infection" was obtained from Swissmedic. The trial synopsis has been adapted to results obtained during the preclinical profiling of the vaccine, and the list of documents needed for the clinical trial application (Swissmedic and Ethics Committee) in Switzerland has been shared with the consortium members. Agreement has been signed between Etna Biotech and STPHI to formal represent the sponsor. The preparation the Investigator’s Brochure is ongoing and as soon as the toxicological studies will be completed, the consortium will be able to submit, without any further delay, the Investigator’s Brochure for the necessary approval to start the clinical trial.
Potential Impact:
MuLeVaClin’s primary goal is to prove through clinical trials an efficacious, affordable and stable prophylactic vaccine, which combines tried and well evaluated leishmaniasis antigens, implemented in well-established vaccine delivery platforms and analyzed on the basis of the latest understanding of the immunological aspects of leishmaniasis. As an effort to confront the major threat to public health that Leishmania represents, MuLeVaClin presents an innovative solution. Current Leishmania control strategies are unfortunately proving to be either ineffective or very expensive, and it continues representing a high burden to the economies of those primarily affected countries. The spread of this disease to previous non-endemic areas is also presenting particular challenges. Moreover, several forms of the disease are anthroponoses or have sylvatic reservoirs, meaning that vector control through insecticide spraying is unfeasible. The result being that all efforts in this direction so far have had limited impact.
The clinical research conducted in this proposal will form a significant step forward in our understanding of this disease, and if successful will represent a major step in tackling the global Leishmania problem. Finally, it is also important to add that the potential benefit of a travel vaccine, for both military and general population, obviously has the potential to add significant value for the SME in this proposal.
List of Websites:
www.mulevaclin.eu

Related information

Reported by

ETNA BIOTECH SRL
Italy

Subjects

Life Sciences
Follow us on: RSS Facebook Twitter YouTube Managed by the EU Publications Office Top