Introduction and Background of the Project

This project is for pre-clinical research for the development and testing of a new adjuvant systems for a therapeutic vaccine for Chagas disease.

Chagas disease is a neglected tropical disease (NTD). Throughout the Americas, an estimated 5-7 million people, most of whom are predominantly poor and marginalized, are infected by the deadly parasite causing Chagas disease, T. cruzi.^1,2 Further, increases in migration and population movements have now started to change the epidemiology and geographic distribution of the disease and have led to its spread to the United States, Europe, Australia, and Japan.^3,4

Tens of thousands of patients die each year from Chagas disease, and the population at risk is estimated to be 75-90 million individuals. About 30% of chronically infected individuals will develop heart complications, with high probability of death, and digestive lesions inhibiting function of the colon or esophagus are present in up to 10% of those affected.⁵ Less than 0.2% of infected individuals receive treatment today.⁶ Children are particularly affected and mother-to-child transmission of Chagas disease is a growing concern.

There is an urgent need for new control and treatment tools for use in chronic Chagas disease, particularly to prevent the onset of heart complications among those infected.^7,8,9,10 Drugs available for Chagas disease have limited efficacy beyond the acute phase of the disease and are not safe to be taken during pregnancy. There is no licensed vaccine for Chagas disease.

The project should lead to preclinical proof of principle for a prototype Chagas disease vaccine comprised of a T. cruzi antigen and E6020 and determine feasibility of manufacture of the vaccine delivery formulation.

How can your partnership (project) address global health challenges?

The Sabin Vaccine Institute Product Development Partnership (Sabin PDP) focuses on developing safe, effective and low-cost vaccines that can prevent human suffering caused by infectious and neglected tropical diseases. The Sabin PDP is an innovative model that relies on private, academic and public institutions to collaborate for preclinical development, vaccine manufacturing, and clinical testing. The Sabin PDP has the ability of accelerating research and development discoveries for NTDs to product development and technology transfer.

This partnership supports current global disease priorities and strategies by providing key data required to develop an urgently needed technology to combat the global Chagas disease pandemic. The proposed studies are on the critical path towards the development of the first prototype Chagas disease vaccine. Based on the recently Global Burden of Disease Study 2010, Chagas disease is now considered one of the world’s most important NTDs.^11,12 A Chagas disease vaccine would be a key technology to address several Millennium Development Goals (MDGs) and targets including the “other diseases” component of MDG 6 and MDGs 4 and 5 to address maternal-child health disparities.

A successful therapeutic vaccine for Chagas disease has a number of significant advantages over currently available treatments and the potential of improved quality of life for the millions suffering from Chagas disease. It would save on costs associated with current treatments and shorten the time required for treatment. Recent models demonstrate the use of a therapeutic vaccine to be highly cost effective.¹³ A vaccine would also lessen associated toxicities of treatment and provide feasible solutions for pregnant women and children.

What sort of innovation are you bringing in your project?

The Sabin PDP in collaboration with key partners is developing a new therapeutic vaccine for Chagas disease.¹⁴ The key innovative aspect of this project is that it combines ongoing and parallel conventional vaccine development strategies for T. cruzi antigen selection and testing with development of a novel adjuvant system.

While aluminum-based adjuvants are capable of generating a strong antibody response, new adjuvants and novel delivery strategies are needed to generate a more robust CD8+ T cell immune responses. This is considered to be essential to the effective control of the parasite T. cruzi, which causes Chagas disease.¹⁵ To address this need, the overall goal of this project is to develop a new vaccine formulation for Chagas disease consisting of a promising protein-based antigen (Tc24) formulated with a novel TLR4 agonist adjuvant (E6020). We anticipate that the novel E6020-based vaccine platform will elicit a stronger and more effective immune response compared to conventional aluminum-based adjuvant formulations, resulting in greater therapeutic efficacy against chronic heart complications caused by Chagas disease.

Due to the versatility of the project’s protein subunit vaccine approach, the proposed adjuvant systems will have applications not only for Chagas disease, but also for a wide range of diseases caused by intracellular pathogens.

Role and Responsibility of Each Partner

Eisai will develop aqueous suspension and oil-in-water emulsion formulations of E6020 for evaluation as an adjuvant for the Chagas disease vaccine candidates. These formulations will be designed to optimize the immunopotentiating efficacy of E6020 adjuvant. The competitive advantage of Eisai is that the company has a large amount of experience formulating E6020 into various types of formulations and that there is a good body of data supporting the characterization, stability and safety of E6020 adjuvant. E6020 also has been previously produced under GMP.

Sabin will be responsible for overseeing the performance of its collaborating partners. This includes responsibility for technical assistance, quality assurance and documentation, financial oversight and project management for this project. Sabin will review project technical data, measure progress against product development milestones and plan ongoing project activities. Sabin will take on responsibility for regulatory guidance and advice for the preparation of the documentation necessary for the successful technology transfer to a cGMP pilot facility, the establishment of a successful testing and stability program for the investigational product, the development of GLP toxicology protocols, and the development, preparation, and filing of an IND to the U.S. FDA or equivalent regulatory filing in an innovative developing country.

BCM will lead the following activities: (a) the optimization, development and characterization of scaled-up processes for the selected Chagas disease vaccine recombinant protein antigen; (b) the formulation of the Chagas protein antigen with Eisai’s E6020 adjuvant; (c) the evaluation of the E6020-adjuvanted vaccine formulations by in vivo (mouse) immunogenicity and efficacy studies; and (d) the development of Trypanosoma cruzi challenge models in mice to assess the ability of the vaccine to ameliorate the effects of chronic Chagasic cardiomyopathy.

Aeras will provide technical support for the process development of the Chagas disease vaccine candidate using Quality by Design and Process Analytical Technology guidelines. Aeras will also engage with BCM in technology transfer by developing the necessary documents, and one laboratory-scale demonstration of the Sabin PDP process at Aeras and producing a non-GMP 20 liter, high-quality scale lot of the Chagas disease vaccine candidate and other related engineering run activities for this project.

Others (including references if necessary)

References;

^[1] "Chagas Disease." Uniting to Combat NTDs. Uniting to Combat NTDs, n.d. Web. 09 July 2014

² Hotez PJ., et al., The global burden of disease study 2010: interpretation and implications for the neglected tropical diseases. PLoS Negl Trop Dis, 2014. 8(7):e2865.

³ Global Chagas disease Coalition (2013) Declaration of the Global Chagas Disease Coalition.   PLOS Speaking of Medicine 

⁴ Hotez PJ (2014) Chagas disease: urgent measures are needed. Huffington Post http://www.huffingtonpost.com/peter-hotez-md-phd/chagas-disease_b_4675010.html

⁵ "Chagas Disease." Uniting to Combat NTDs. Uniting to Combat NTDs, n.d. Web. 09 July 2014

⁶ DNDi, unpublished data

⁷ Apt, W., Current and developing therapeutic agents in the treatment of Chagas disease. Drug Des Devel Ther, 2010. 4: p. 243-53.

⁸ Buckner, F.S. and N. Navabi, Advances in Chagas disease drug development: 2009-2010. Curr Opin Infect Dis, 2010. 23(6): p. 609-16.

⁹ Lee, B.Y., et al., The Potential Economic Value of a Trypanosoma cruzi (Chagas Disease) Vaccine in Latin America. PLoS Negl Trop Dis, 2010. 4(12): p. e916.

¹⁰ Lescure, F.X., et al., Chagas disease: changes in knowledge and management. Lancet Infect Dis, 2010. 10(8): p. 556-70.

¹¹ Murray CJ, Vos T, Lozano R, Naghavi M, Flaxman AD, Michaud C, et al. Lancet. 2012;380(9859):2197-223.

¹² Peter Hotez M.D. "America's 'New' Diseases of Poverty." The Huffington Post. TheHuffingtonPost.com, 08 Jan. 2014. Web. 08 Apr. 2014.

¹³ Lee BY, Bacon KM, Wateska AR, Bottazzi ME, Dumonteil E, Hotez PJ. Human vaccines & immunotherapeutics. 2012;8(9):1293-301.

¹⁴ Dumonteil E, et al. Accelerating the development of a therapeutic vaccine for human Chagas disease: rationale and prospects. Expert Rev Vaccines. 2012 Sep;11(9):1043-55.

¹⁵ Rodrigues MM, de Alencar BC, Claser C, Tzelepis F, Silveira EL, Haolla FA, et al. Memorias do Instituto Oswaldo Cruz. 2009;104 Suppl 1:281-7.

Final Report

1. Project objective

There is an urgent need to prevent the onset of clinical sequela resulting from chronic Chagas cardiomyopathy by developing new and improved treatments. The objective of this project was to advance pre-clinical research for the development and testing of a therapeutic vaccine for Chagas disease with a new adjuvant system, as an alternative or complimentary intervention to halt progression of Chagasic cardiomyopathy.

2. Project design

The project consisted of developing a reproducible process for scalable production, formulation and testing of recombinant Tc24-C4, a parasite vaccine candidate with E6020, a novel immunostimulant, and its evaluation as a stand-alone technology and in a vaccine-linked chemotherapy approach with benznidazole. The effect of therapeutic vaccination with Tc24-C4/E6020 was evaluated in acute and chronic mouse models of infection.

3. Results, lessons learned

The Sabin PDP has successfully developed a reproducible process for scalable production, formulation and testing of recombinant Tc24-C4, a parasite vaccine candidate. This included optimization of a reproducible and robust production process for Tc24-C4 at the 10 L scale and execution of an engineering non-GMP 20 L run. Data suggest protein yields and purity comparable to internal reference standards. A process for preparation of the vaccine adjuvant E6020 as an oil-in-water emulsion was optimized and reproducible batches of Tc24-C4 and E6020 produced. Furthermore, a new medium-throughput analytical method was developed for the quantification of E6020 emulsions.

Mice were preclinically infected with T. cruzi H1 parasites, then vaccinated at 7 and 14 days post infection for acute studies, or 70 and 98 days for chronic studies. It was observed that Tc24-C4/E6020 vaccination and challenge results in induction of T_H1-type cellular immunity, increased host survival, diminished cardiac fibrosis and pathology, and reduced cardiac parasite loads in acutely and chronically infected mice compared to controls. Cardiac parasite burden was significantly reduced, and 60% of mice became consistently aparasitemic after treatment. Furthermore, it was observed that that vaccination during the indeterminate phase of disease induces a robust and durable antigen specific immune response resulting in reduced cardiac pathology. With respect to the combination of benznidazole with Tc24-C4/E6020, antigen specific immune responses were robust in groups receiving the vaccine, either alone or in combination with low dose benznidazole treatment.

As the next step, the Sabin PDP will proceed with a cGMP campaign for Tc24-C4/E6020 and conduct a GLP toxicology study. To assess the suitability for human translation, the Sabin PDP will conduct an immunogenicity study in chronic naturally-infected non-human primates to reproduce and assess results in an animal model closely resembling human disease.