Medical Device Link.

ASSAY DEVELOPMENT

Figure 1. The endotoxin activity assay for assessment of gram-negative sepsis from Spectral Diagnostics Inc. (Toronto).4

There is little doubt that immunoassays and immunoassay systems will continue to be primary players in diagnostic applications for many years. The need for assay systems fuels investment and encourages the start-up of companies focused on developing new immunoassay technology and products.

Bringing an assay from lab bench to marketplace involves a diverse range of skills and experience. Careful planning, milestones, and other production goals are key to this process, and assay development requirements have been documented in a number of books.^1–3 Beyond these basic concerns, however, immunoassays require detailed, step-by-step plans to ensure a successful market launch.

Outlined in this article is a generic, phased approach for the development and commercialization of immunoassays and immunoassay systems for most common analytes, including blood components, pathogens, cancer markers, and cardiac risk factors. TC Associates Inc. (West Boxford, MA) has used this method to help develop a variety of products, such as the recently approved clinical assay for gram-negative sepsis from Spectral Diagnostics Inc. (Toronto) (see Figure 1) and the RAMP point-of-care diagnostics platform from Response Biomedical Corp. (Burnaby, BC, Canada) (see Figure 2). This approach can be applied to assay development for all major markets. Although the strategy described here is for immunoassays, it can also be adjusted to develop nucleic acid probes, biosensors, microarrays, and other assays.

Basic Assay Requirements

Figure 2. The RAMP immunoassay platform for cardiac markers from Response Biomedical Corp. (Burnaby, BC, Canada). RAMP tests for infectious agents, such as West Nile virus, and biological warfare agents are also available.

Successful new clinical immunodiagnostics must meet one or both of two primary needs. First, if the new assay or system is a competitor to an alreadyestablished assay, it must show improved performance and productivity—for example, lower cost per assay, greater efficiency and throughput, and, if possible, lower capital equipment investment and less dedicated technician time. Second, if the product claims new diagnostic capabilities, these must address long-standing needs. Such systems are not, initially, cost limited. Cost becomes a factor only as competitors develop and offer similar assays or systems.

Manufacturers must also weigh the risks and benefits of developing and commercializing a new immunodiagnostic. The rate of false-positives and false-negatives must be factored into assay marketing decisions, as must the effect of the assay and its failure rate on the detection and prediction of disease, and the management of patients.

In clinical diagnostics, risk-benefit considerations include not only concerns connected with the actual testing (e.g., the use of radioisotopes), but also those associated with the use of the assay results. These latter risks may range from incorrect diagnoses to moral quandaries surrounding tests for diseases for which there is no current cure.

For instance, in the United States, there is considerable resistance to the use of diagnostic tests for genetic diseases such as cystic fibrosis and muscular dystrophy. The argument made by opponents is that an indication that parents are carriers of the disease, or that a fetus will express the illness, could lead to abortion and involve manufacturers in the social implications of such an action. Conversely, if assays are available for genetic diseases but lack high accuracy and fail to predict them consistently, a diagnostics company could face potential legal ramifications. Such sociopolitical factors may, at least in the case of some diseases, outweigh the benefits of a specific clinical assay to patient management and improvements in quality of life.

Designing an Assay

It is critical to assess and decide on the design of a new immunodiagnostic early in the commercialization process. These considerations should include a survey of markets for the assay as well as an assessment of other competitive assays already on the market. These analyses allow projections of both potential market share and return on investment.

In developing a new assay for an established immunodiagnostic system, or generic OEM reagents for a variety of immunodiagnostic systems, design is dictated by system architecture and is thus straightforward. However, system requirements, such as detection method and antibody specificity, may also limit the number of new assays that can be developed for the system.

Immunodiagnostic kits and stand-alone tests allow a broader selection of design characteristics. Currently, immunoassay kits and, more recently, anti- body-based microarrays, are being designed to meet criteria that increase their ease of use and cost-effectiveness. Examples of such criteria are the following:

• High sensitivity.

• High specificity.

• Rapid data output (from seconds to a few minutes).

• Ability to assay multiple analytes in the same test (panels).

• Simple operation (homogeneous).

• Reagentless format.

• Minimal or no sample preparation.

• Portability.

• Low cost per assay.

• No or low risk to the user.

Design considerations must also focus on the end-user (i.e, physician, nurse, technician, or layperson) and the place where the assay will be used (i.e., physician’s office, clinical laboratory, critical-care unit, or home). These factors determine the type of instruction and training materials that must be included with the assay. They also define the level of complexity assigned to the assay under the Clinical Laboratory Improvement Act of 1988.

Companies must perform accelerated shelf-life testing on the test kit and its individual components to determine realistic shelf life, storage conditions, and usage conditions for the assay. This information is also critical to assessing the overall quality control for the assay and the instructions for its use.

Finally, disposal methods must be considered and included in the assay instructions. For example, radioimmunoassays require that all radioisotope regulations be followed. Usage must comply with not only federal regulations for disposal, but also those of each state in which the assay will be sold and used.

Commercializing a New Diagnostic

Bringing a new immunodiagnostic to market requires interdisciplinary skills and experience. These may include technical expertise in biochemistry, immunology, electronics, engineering, polymerics, and ergometrics; quality control, quality assurance, and regulatory requirements; manufacturing and process experience in scale-up, technology transfer, and packaging; and marketing and distribution knowledge. For clinical diagnostics (i.e., tests for human use), experience with clinical trials is also required.

During commercialization, the following key parameters must be addressed by the development team:

• Technical performance to specifications.

• QA/QC requirements and protocols.

• Projected scale-up and production problems and solutions.

• System and system-component costs and the means to minimize such costs.

• Competitive design and use considerations.

• Manufacturing and production.

• Regulatory submissions (as necessary).

• Packaging.

• Market release and monitoring.

Oftentimes, new companies will not have the necessary experience in-house and must decide whether to hire the employees needed or seek help from outside consultants. The need for outside consultants can arise as early as in the design concept phase of the project.

Figure 3. A phased approach for the development of a new immunodiagnostic. (Click to enlarge.)

The seven-step, phased program presented in this article can be used both to guide immunodiagnostic commercialization and to measure success at each stage of the development program (see Figure 3). Although focused on human clinical diagnostic tests here, the program is also applicable, with appropriate modifications, for developing immunodiagnostic tests for veterinary, environmental, food, and pharmaceutical use. In these cases, however, clinical trials are not necessary; nor, if the products are intended for internal use, are the marketing, packaging, and release steps.

Phase 1: Initial R&D Leading to a Laboratory Prototype Assay

The goal of Phase 1 is a laboratory prototype that reduces the technology to practice and proves the intent of the assay. R&D cost is a function of time, available investment capital, allowable risk, and projected profits. Careful, up-front planning and management can decrease the costs and time to develop a new assay.

Phase 1 should include the following tasks:

• Defining needs and the target product.

• Performing a technology audit and/or selecting the technology to be used.

• Producing R&D and testing plans for the product prototype.

• Developing and testing the actual assay.

• Conducting regular reviews and refocusing of the product team.

In many cases, the base technology for the assay is either the result of other studies or needs or has been discovered by chance. In these instances, initial development is typically less organized and less focused.

Phase 2: Technology Review and Design Concept Selections

Entering the second phase of assay development assumes that the manufacturer has decided to commit further time and resources to developing the laboratory prototype. At this point, the assay begins to move from a primarily research phase into true development. This transition can prove critical; trade-offs often must be made between interests that are academic and those necessary to ensure successful assay commercialization.

The following tasks should be completed in Phase 2:

• Conducting a technical audit of work to date.

• Defining the strengths and weaknesses of the technology or product compared those of competing products.

• Selecting the design concept.

• Setting performance specifications.

• Formalizing of the final development and commercialization program, including projected cost and time.

• Formally deciding to proceed with assay development.

• Forming development, management, and marketing teams.

The goal of Phase 2 is to create a development plan that defines the assay design concept and specifications. This step often uses resources outside the development company (a third party to perform the technical audit, OEM suppliers to provide raw materials and reagents, etc.). It is in this phase that the product concept, goals, and results to date should be reviewed critically to decide whether to proceed with the development program.

Phase 3: Testing to Specifications

After a development plan has been put together, the assay returns to the laboratory to test its reproducibility and accuracy using assay components and reagents (for example, antibodies and conjugates for an immunoassay). These are either produced in pilot scale in-house or are obtained through OEM companies.

Steps in this phase include the following tasks:

• Purchasing or producing pilot lots of assay components and reagents.

• Developing and implementing QA/QC methods for all assay components.

• Testing the reproducibility and accuracy of the assay.

• Formalizing the assay method and packaging.

• Creating the initial marketing plan based on primary marketing research.

• Selecting sites for clinical trials.

Phase 3 will prove whether the assay can meet its design and performance specifications. In most cases, this phase will take more time and cost more than expected as seemingly minor performance problems become major hurdles. A strong, closely interacting development team is critical for addressing these issues.

Phase 4: Final Design and Testing

The goal of Phase 4 is to build and verify the manufacturing prototype of the assay. By the end of this development step, the final immunodiagnostic product performance and format should be near completion and ready for clinical trials.

Manufacturers should undertake the following tasks:

• Optimizing product components and the total product package.

• Producing at least three pilot batches of all assay reagents and components to specifications.

• Fabricating and testing the final product prototype to specifications.

• Reviewing design and manufacturing considerations to minimize downstream manufacturing problems and costs.

• Creating a first draft of documentation and engineering drawings.

• Meeting with the appropriate regulatory agency to discuss regulatory submissions (e.g., 510(k) or premarket approval [PMA] application in the United States for a clinical immunodiagnostic) and the required clinical testing.

• Drafting the final version of the clinical trial plan and submitting it to the proper regulatory agency for comment and, if applicable, approval.

• Preparing documents and facilities, as appropriate, for good manufacturing practice (GMP) and ISOapproval compliance.

• Setting up and supplying beta sites to assess assay performance.

Phase 5: Clinical Trials

Once a prototype has been built and verified, the actual testing of the assay can begin. Phase 5, which is geared toward successfully completing clinical trials and receiving regulatory approval for the assay, involves the following steps:

• Training personnel at clinical trial sites to use the assay.

• Coordinating data collection and review.

• Shipping assay kits and/or reagents.

• Providing troubleshooting and technical assistance to the sites as needed.

After the trial is completed, data must be interpreted and prepared for the approval application. The documentation involved in regulatory submissions can be monumental; as a result, clinical trials can prove daunting to the assay team, especially to personnel who have not had much experience with the process. Since the trials are often so time-consuming, many companies choose to contract a third-party service company to handle the data collection and reduction.

Phase 6: Design Changes, Testing, and Transfer to Manufacturing

In most cases, clinical trials will reveal that changes in either assay specifications or components, or both, are necessary. For example, the sensitivity, specificity, or positive-negative predictive value of the immunoassay may need to be corrected. With luck, such revisions will be minimal and quick.

Phase 6 encompasses all activities necessary for the prototype assay to receive final regulatory approval. The following steps are included in this phase:

• Determining and implementing assay design specifications or format changes.

• Conducting limited testing of the modified assay to meet specifications.

• Submitting any necessary addenda to the primary regulatory document.

• Finalizing packaging design.

• Completing final manufacturing documents.

• Transferring first production component lots to manufacturing.

• Completing QA/QC documents.

• Completing all GMP documents; preparing for a GMP site visit.

• Finalizing marketing and distribution plans.

Phase 7: Manufacturing and Product Release

Upon completion of the final phase of the development process, the assay should be under full production in numbers projected by the marketing plan. Distribution networks and shipping methods should be in place, and GMP compliance should be approved.

Specific steps in Phase 7 include the following:

• Enacting full-scale manufacturing and assembly of the assay.

• Undertaking reliability and QA testing.

• Finalizing technical release documents and applications.

• Setting distribution and marketing plans into action.

• Collecting and reviewing customer feedback six months after product release.

Timeline and Costs per Phase

Table I. Estimated time and costs to develop a new clinical immunodiagnostic. (Click to enlarge.)

Experience using this model has shown that the generic development and commercialization of a new stand-alone diagnostic assay may take from 34 to 54 months between Phase 2 and Phase 7 and cost approximately $3.4 million to $7.3 million (see Table I). Upfront R&D can play a key role in the final cost of developing an assay technology; a failure to focus and evaluate R&D can quickly stall any program.

Costs and time may be considerably less when a new IVD is developed for an existing format or system. In these cases, assay development may be achieved in as little as 10–15 months with appropriate cost savings.

Richard F. Taylor, PhD, is president of TC Associates Inc. (West Boxford, MA). He can be reached at TCAdtaylor@cs.com.

In cases in which a new instrument is developed for the assay (e.g., a colorimetric, fluorescence, or chemiluminescence photometer), additional costs from $1 million (for off-the-shelf technology or the modification of an existing instrument) to as much as $12 million (for designing and manufacturing an entirely new instrument) should be added. Since any new instrument must be ready for the clinical trials, development should be started as early as Phase 2.

Conclusion

The phased program described here represents only the first-level, key issues for each step in the commercialization of a new assay. At the next level of planning, each phase and issue must be broken down into tasks unique to the assay. These tasks will direct the actual hands-on work, which must be carried out to bring the assay to market.

Once an assay leaves basic research and enters the development phases of the program, a team should monitor all aspects of its testing and manufacture. Commercial clinical immunoassays also require that regulatory and marketing needs be addressed early on in the process. However, by maintaining a focused approach to assay development, an IVD company can decrease the risk that a product will not meet specifications and increase the probability that the assay will be developed and commercialized within cost and time constraints.

---