Nick Allan

TPP: The secret to efficient diagnostic device design

efficient diagnostic device design2020 highlighted the importance of rapid diagnostics.  Many companies approached us in 2020 looking to develop a better COVID-19 diagnostic test.  No matter what the technology, state of development or size of the company, we have found that the key differentiator between a successful medical device product and an unsuccessful one, was having a good, well-defined Target Product Profile (TPP) going into the development cycle.

A Target Product Profile is defined by the world health organization (WHO) as a document that outlines the desired ‘profile’ or characteristics of a target product that is aimed at a particular disease or diseases. TPPs state intended use, target populations and other desired attributes of products, including safety and efficacy-related characteristics.  In fact, the TPP is such a critical document that the Special Programme for Research and Training in Tropical Diseases (TDR) created and maintains a database called the Health Product Profile Directory that lists the TPPs of critical medicines, vaccines, diagnostics and medical equipment.

The concept of a TPP has origins in late 1990’s with the FDA and pharmaceutical industry collaborating to improve interactions between sponsors and the agency during the complex regulatory approval process for new drug submissions.  These meetings eventually led to the draft guidance document outlining the TPP as a strategic development process tool:  Guidance for industry and review staff Target Product Profile — a strategic development process tool. 2007.

While originally aimed at pharmaceutical drug development, the TPP process can be adapted by medical device and diagnostic programs for successful product development. Implementing a robust and disciplined TPP process can help drive alignment in cross-functional strategies, leading to a more effective and cohesive product development process.

While the FDA guidance document outlines over seventeen (17) specific key sections required for a well-defined TPP, the essential elements can be distilled down to a summary of the following four (4) critical features:

  • Define the product under development (what is the diagnostic device you are developing and what is its intended use). Consider, for example, an Enzyme Immunoassay Antibody (EIA) test to help determine if people have antibodies to SARS-CoV-2.  The intended use is to determine if an individual has generated an antibody response to SARS-CoV-2.
  • Outline the desired characteristics and features. In our EIA example, this would be a kit containing all lot specific material required for testing. This includes a standard, coated 96-well EIA plate, and all related lot-specific reagents such as conjugate and calibrators.  The target user is a laboratory trained health care professional and the target use setting is a Medical Laboratory working to appropriate quality & competence standards.
  • Identify the studies that must be completed to demonstrate the product’s performance, efficacy and safety. In our EIA example this would include real time kit reagent stability data (at least 6 months at 2-8°C or 12 months at -20°C) and sufficient experimental data to appropriately demonstrate desired clinical sensitivity and analytical specificity that considers cross-reactivity with other coronaviruses (i.e. SARS-CoV-1).
  • Describe the key features of the product that provide a competitive advantage. For our EIA example, we would typically need to see clinical sensitivity of ≥98% (with 95% confidence intervals of 96-100%) on specimens collected 20 days or more after the appearance of first symptoms and an extremely competitive cost of goods sold (CoGS) target that is well defined.

While the diagnostic device TPP document provides tremendous value by outlining a very detailed product development road map (with detailed product specifications, performance and evaluation criteria) one could argue that the true value of the TPP is only realized if the TPP process is employed very early in the concept development phase. At that time, the TPP provides powerful multi-faceted strategic development which drives first principles concept development and business planning considering which opportunities have the highest return on investment (ROI), determining differentiating product claims, positioning within the market and, in some cases, developing a multi-application platform system rather than targeting just one specific indication.

Applying the TPP concept to early diagnostic device product definition. Just because you have a unique break-through diagnostic platform does not mean you should start product development without a proper plan first. During the early spring of 2020, we were inundated with enquiries from researchers with variations on CoVID-19 diagnostic device applications. Often these potential diagnostic systems missed the mark as they failed to meet some of the basic elements that are covered by a high-level TPP. The principles of the TPP should also be applied to pre-development strategic planning and analysis. Before committing to a long and expensive product development pathway, first consider this TPP inspired top ten check list:

  • Product Definition: What are you designing? Provide a concise summary description of the product.
  • Diagnostic Device Category: What is your intended indication for use?  Does the device provide an additional or new indication for an existing product?
  • Strategic Fit and Value: How well does this diagnostic device fit within the core expertise and capabilities of your company?
  • Value to Patients: What is the specific value of this diagnostic device to patients? Does it offer diagnostic, therapeutic, safety or ease of use advantages over existing or upcoming diagnostic devices in this category?
  • Competitive position: Does this device have a competitive advantage (i.e. Point of Care or time to result)?  Does the company have a competitive advantage (i.e. distribution network)?
  • Intellectual Property (IP) position: Brief summary of the IP position of the device.  We have seen a number of technologies developed in a university setting where the institution’s tech transfer office, and not the inventor or company, defined the IP/Royalty structure that was developing the platform.  This was not clearly understood early on by the company developing the platform and led to a costly design change midway through assay validation.  A costly misstep that the TPP process would have easily avoided.
  • Rationale for success: Brief summary as to why the development team and stakeholders believe this product will be successful.  It does not hurt to bring in outside Key Opinion Leaders (KOL), potential users and customers to weigh in on this point.
  • Factors for success: A brief statement defining the company’s core competencies and the market conditions that will drive a successful outcome.  Understanding market access and key product differentiators (i.e. reagent cost, time to result, usability) is a critical driver of the ultimate success of the product.
  • Key Risk Factors: A brief statement that identifies possible risks.  This does not need to be comprehensive, but should touch on potential patient risk, risks of false negatives and positives, and development risks (i.e. key component supply chain and reagent shelf life).
  • Competition: Are there alternatives to this product?  What is the market penetration and what are the key differentiators to the potential product under development?

A well-defined TPP provides the structure to ensure that a company embarks on a product development program that is efficient and effective to reach the desired commercial outcome.  If used properly, a TPP can help address issues early in the product development process and prevent late-stage development failures.  The TPP is the secret to successful development of a diagnostic device!

Image: StarFish Medical

Nick Allan is the Bio Services Manager at StarFish Medical. He has provided innovative solutions to client issues ranging from proof-of-concept studies for rapid detection point of care assays to full scale regulatory submission studies, and designed and facilitated more than 500 Unique Research Protocols.

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