Introduction and Background of the Project

1.  Introduction

WHO urgently needs new diagnostic tests to achieve the NTD 2021-2030 Roadmap goal of global trachoma elimination by 2030 and has published a TPP defining the desired product characteristics. In this project, we will deliver a fully TPP-compliant RDT for trachoma surveillance in both a dipstick and a cassette version thus covering all the various use case scenarios including use with dried blood spots (DBS) in regional, district, and village laboratories (dipstick) or with fingerstick blood at the point of care in low-infrastructure environments (cassette). Our test will come with a complete set of laboratory and field validation data generated by the Centers for Disease Control and Prevention (CDC) and The Carter Center (TCC), respectively, a novel heat-stable formulation of a positive control antibody, and an ISO13485-compliant manufacturing process independently validated at Big Eye Diagnostics, Inc. (BEDx) through pilot production of 30’000 tests, hence will be ready for programmatic adoption by WHO, including Pre-Qualification (WHO PQ) or ERPD Review if deemed necessary by the stakeholders. For the first time, national programs will be able to conduct trachoma surveys using a commercial and fully TPP compliant rapid test instead of ophthalmologic examination. Our RDT will provide a standardized and objective method that ideally integrates with other surveillance programs.

2.  Project objective

The overarching objective of this project is to deliver a rapid diagnostic test (RDT) to detect exposure to Chlamydia trachomatis, the pathogen causing trachoma. Our test will meet all key criteria of WHO’s Target Product Profile (TPP) for trachoma surveillance and will be delivered in both a dipstick and a cassette format. It will come with a complete set of laboratory and field validation data, as well as an ISO13485 manufacturing process validated through pilot production of 30’000 tests, hence will be ready for programmatic adoption and possible Pre-Qualification or ERPD Review by WHO. Our RDT will respond to a critical and urgent need with no alternatives and no competition in sight at the present time. In addition, we will also attempt to make a contribution towards rendering CDC’s laboratory-based multiplex bead assay (MBA) more amenable to lower-infrastructure usage in LMICs by generating pre-conjugated, lyophilized Luminex beads with a stringent quality control (QC) no longer requiring a cold chain for shipping.

3.  Project design

We will pursue the following 6 specific objectives:

-  Objective 1 (MBL): One key factor to ensure reproducible product quality is to have a constant, reliable source of the biological components of the test. MBL will be in charge of this key task and produce the C. trachomatis antigen. In addition, MBL, DDTD, and the CDC will collaborate to generate pre-conjugated lyophilized Luminex beads with an appropriate, standardized positive control in support of a more widespread use of CDC’s laboratory-based multiplex bead assay in certain LMICs.

-  Objective 2 (DDTD): A functional prototype RDT has already been generated and validated by the CDC, and subsequently reproduced and partially optimized at DDTD. This test will now be fully optimized until it satisfies all key TPP criteria.

-  Objective 3 (CDC): Once an optimized candidate test has been nominated by DDTD, CDC will provide an independent validation of TPP compliance in terms of sensitivity and specificity. The final selection of the candidate RDT to enter development will be based on sensitivity and specificity as well as result consistency/accuracy, time-to-result, result stability, and thermal stability, with the goal to select one candidate RDT for further development.

-  Objective 4 (TCC): After successful validation of TPP-compliance by CDC, TCC will work with the Trachoma Monitoring Laboratory at Amhara Public Health Institute (APHI) in Ethiopia, to further validate the RDT for diagnostic performance and user-friendliness (feasibility) in one of the intended use cases.

-  Objective 5 (DDTD, BEDx): DDTD will develop a robust, ISO13485-compliant large-scale manufacturing process commensurate with the expected demand forecast of up to 700’000 tests/year and the ideal target pricing of <$5 per test required by the TPP. The low-throughput card-by-card production will be replaced by a high-throughput reel-to-reel (R2R) process. The new R2R manufacturing process will be validated independently by BEDx through pilot production of 30’000 tests.

-  Objective 6 (DDTD): DDTD will liaise with a social anthropologist and a health economist with the goal to acquire socio-economic data on optimizing test acceptance by local populations and on testing costs of programmatic surveys. A concluding meeting will be organized involving all key stakeholders with the goal to obtain a unanimous recommendation for the programmatic adoption of the new test by WHO for post-MDA trachoma surveillance.

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

Trachoma is a public health problem in 42 countries and is responsible for the blindness or visual impairment of about 1.9 million people, with 125 million people living in trachoma-endemic areas at risk of contracting the disease. Trachoma control today relies on antibiotic mass drug administration (MDA) which, in turn, critically depends on field-deployable diagnostic tools to guide decisions on MDA initiation and cessation. None of the currently available diagnostic approaches and tools is suited for this purpose. Recognizing the urgency to act, the WHO has released a TPP defining the criteria new diagnostic tools will need to meet. Releasing a TPP is the strongest possible signal the WHO can give regarding the importance of a particular disease as a global health problem and the urgency to develop new diagnostics. This project will deliver the first fully TPP-compliant RDT for trachoma surveillance. We respectfully submit that a first-in-class tool that will support the elimination of trachoma, with no alternatives or competition currently in sight, will address an unmet need of paramount significance for global public health.

What sort of innovation are you bringing in your project?

-  Innovation 1: The development of a first-in-class device is in itself an innovative contribution. Moreover, we plan to deliver the new test in both a dipstick and a cassette version which, together, will cover all the use cases encountered in trachoma programs including use with dried blood spots  in regional, district, and village laboratories (dipstick) or with fingerstick blood at the point of care (cassette).

-  Innovation 2: The use of CDC’s MBA is currently limited to well-equipped laboratories present only in a handful of LMICs, as it requires skilled operators to conjugate the fluorescent beads to the C. trachomatis antigen prior to use. In addition all the MBA reagents require a cold chain for shipping to LMICs. To enable a more widespread use of the MBA in more regional LMIC laboratories, and ideally even down to the level of district labs, we propose to develop an MBA/Luminex assay kit containing all necessary reagents and components in a ready-to-use, heat-stable form, which can simply be reconstituted just-in-time at the corresponding laboratories in LMICs.

-  Innovation 3: The TPP calls for an external performance control, which will allow the end users to periodically check whether the RDT still performs to specs. A monoclonal positive control antibody has already been developed at CDC. However, antibodies are not heat-stable rendering shipment and use in LMICs difficult. To solve this problem, we have recently developed a novel method for rendering positive control antibodies entirely heat-stable. We have used this method to generate a positive control for the river blindness project and shown it to be stable at 50°C for > 2 weeks. Our new method will allow external control antibodies for many other NTD diagnostics to be shipped to LMICs without a cold chain, which represents a highly impactful improvement of current-best practice.

Role and Responsibility of Each Partner

-  Drugs & Diagnostics for Tropical Diseases (DDTD): RDT development, optimization, and validation of TPP compliance. Development of an automated, ISO13485-compliant reel-to-reel manufacturing process. Development of standard operating procedures (SOPs) and QC protocols for pre-conjugated lyophilized MBA/Luminex beads.

-  Medical & Biological Laboratories Co., Ltd. (MBL): Production of the C. trachomatis antigen, first in R&D-grade, then in ISO/QMS-grade quality. Validation of SOPs and QC protocols for generating pre-conjugated, lyophilized MBA/Luminex beads through pilot lot production.

-  The Carter Center (TCC): External validation of the candidate RDT in a regional laboratory located in a targeted trachoma-endemic LMIC, most likely at the Trachoma Molecular Laboratory at the Amhara Public Health Institute (APHI), Ethiopia.

-  Big Eye Diagnostics, Inc. (BEDx): Independent validation of the new reel-to-reel manufacturing process and QC protocols by producing 3 pilot lots of 10’000 test units. In the longer term, after completion of the current project, BEDx will take over test manufacturing and commercialization.

In addition to these four formal team members, we will collaborate with the Centers for Disease Control and Prevention (CDC), who will carry out the external validation of the prototype and candidate RDTs and of pre-conjugated, lyophilized MBA/Luminex beads. Moreover, Dr. A. Solomon from the World Health Organization (WHO), the focal point for trachoma at WHO, has agreed to act as an official Observer on this project and, as such, will participate to all project consortium meetings.