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Three things every patent analyst should know when searching prior art

Median damages for patent infringement awarded by courts are rising and total billions of dollars annually. A significant burden of responsibility falls to patent analysts, who, with a comprehensive prior art patent search, can help confirm the novelty of an innovation before commercialization. Incomplete prior art searches can also result in invalidated patents or rejected patent applications. As a patent analyst, how can you ensure your intellectual property (IP) search strategy misses nothing?

1. Know your topic to ensure your search is comprehensive

Before initiating your prior art search, ensure you understand the topic and domain to confidently identify all relevant synonyms and classifications. This will save time and enhance the efficiency of your search efforts. If you are looking for prior art on a specific small molecule drug or polymer, you must know its chemical formula, Markush structure, any scientific, generic, or brand names that it is known by, potential applications, and other parameters that drive IP.

For example, prior art searches for antibody-drug conjugate (ADC) development require multifaceted subject matter knowledge and strategy far beyond basic name searches. ADCs are designed to selectively deliver a toxic payload directly to target cells and consist of three parts: the antibody, which is the targeting moiety, the highly potent cytotoxic payload, and a linker. IP analysis in this field must include not only the entire ADC but also all individual components. Below are a few examples:


  • Specific sequence searches: This includes full antibody sequences (heavy and light chains), or fragments, focusing on the complementarity-determining region (CDR), which is essential for binding specificity.
  • Variants and derivatives: Searches must encompass genetic variants, chemical modifications, and the presence of unusual amino acids. Given the significant impact a single modification can have on an antibody's functionality, accurate sequence identification is crucial.

Linkers and payloads:

  • Chemical structure searches: These are essential for identifying the chemical nature of linkers (including peptide-based ones) and payloads. This step often involves Markush searches to cover broad generic formulas and related combinations. Use databases containing the keys to substances in patents, such as MARPAT®.

A comprehensive ADC search is a combination of search techniques and approaches, which requires a precision search for individual components and analyses of those combined results. If any critical aspects of the ADC were not considered during the initial brainstorming process, searchers could miss relevant prior art, leading to significant downstream risks.

Frequent, early collaboration between IP and R&D teams can bolster understanding of the topic and decrease the chance of missing subtle scientific details. During the search process, communicate frequently with your requestor or other key stakeholders to leverage their subject matter expertise. Regular updates on your progress not only keep them informed but open the door to valuable insights and commercialization plans that can help shape your search strategy. Once you are in alignment, you can continue to iterate and refine your search as the research evolves.

2. Utilize multiple tactics for a comprehensive prior art patent search

Several strategies and approaches should be used to achieve a comprehensive prior art search:

  • Keyword/text search: Identify the main concepts of the target innovation and develop keywords and terms from those concepts. Start with broader terms that focus on different aspects of the technology, then add more specific or ‘narrow’ keywords. Then, look at entries that use both or all these keywords. The broad-to-narrow search strategy virtually ensures that the main concept will be present in the search results.
  • Patent classification search: Identify the relevant technology field and create a search within that specific classification. There are several unique systems with different classifications (e.g., chemistry and metallurgy, human necessities, textile and paper, etc.) to choose from, including International Patent Classifications (IPCs), Cooperative Patent Classifications (CPCs), and more.
  • Citation search: Identify closely related patents based on their connections to other patent references. In a backward citation search, you can find all of the literature cited by a record, and in a forward citation search, you can find all the literature that a record is cited by to find similar patents.

Tip: CAS STNext® delivers value-add databases where entries have attached abstracts created by scientific IP experts that make it easier to understand the IP of entries by reducing legal jargon. Value-add databases help ensure that concepts are connected and that you are capturing relevant information and navigating standardized numeric property measurements.

3. Use tools that bridge the vast differences between databases

There can be differences in the coverage of the databases, and systems should make it clear what they offer. Knowing what you can expect from each database before searching helps you use your time more effectively and formulate your search to maximize its breadth and depth. Answer the following questions with the included information:

  • What countries are covered?
  • What dates are covered?
  • What types of documents are covered?
  • First-level vs. value-add

Platforms like CAS STNext allow you to search a cluster of similar databases at the same time, reducing search time significantly.

4. Comprehensive prior art patent searches can be difficult, but persistence pays off

When conducting a comprehensive prior art patent search, expect it to take 20% of your time to find 80% of the relevant documents and 80% of your time to find the other 20%. Being persistent even when you start to feel the diminishing returns of your efforts is the hallmark of an excellent patent searcher and an essential risk mitigation strategy. Although a search is never truly complete, once your results using different strategies begin to converge, you are getting close.

Avoiding missed records means avoiding wasted R&D spending and costly financial risks. While it can be challenging to complete a comprehensive search, maximizing your search strategy can mitigate risk and boost your confidence in your result set. CAS STNext gives you the complete view you need for confident decisions throughout the innovation lifecycle.

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