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Generating functional protein variants with novel or improved characteristics has been a goal of the biotechnology industry and life sciences, for decades. Rational design and directed evolution are two major pathways to achieve the desired ends. While rational protein design approach has made substantial progress, the idea of using a method based on cycles of mutagenesis and natural selection to develop novel binding proteins, enzymes and structures has attracted great attention. Laboratory evolution of proteins/enzymes requires new tools and analytical approaches to create genetic diversity and identifying variants with desired traits. In this pursuit, construction of sufficiently large libraries of target molecules to search for improved variants and the need for new protocols to alter the properties of target molecules has been a continuing challenge in the directed evolution experiments. This review will discuss the in vivo and in vitro gene diversification tools, library screening or selection approaches, and artificial intelligence/machine‐learning‐based strategies to mutagenesis developed in the last 40 years to accelerate the natural process of evolution in creating new functional protein variants, optimization of microbial strains, and transformation of enzymes into industrial machines. Analyzing patent position over these techniques and mechanisms also constitutes an integral and distinctive part of this review. The aim is to provide an up‐to‐date resource/technology toolbox for research‐based and pharmaceutical companies to discover the boundaries of competitor's intellectual property (IP) portfolio, their freedom‐to‐operate in the relevant IP landscape, and the need for patent due diligence analysis to rule out whether use of a particular patented mutagenesis method, library screening/selection technique falls outside the safe harbor of experimental use exemption. While so doing, we have referred to some recent cases that emphasize the significance of selecting a suitable gene diversification strategy in directed evolution experiments.

Driven by increasing instances of successful ‘at-risk’ launch of patented drugs in America and Europe, the strategy of using ‘proactive infringement’ as a legal tool is now getting-in, in developing countries. The rationale behind launch-at-risk is to counterbalance the innovator companies’ strategies of getting the patented product life extended through protecting improvement innovations and maintain market exclusivity even after the expiration of the compound patent. The battle for market and drive for higher profits between generics and innovator drug companies has extended the application of at-risk launch of the generic drugs even when compound patent is still running. Sitagliptin (Januvia) may be ranked at top of the drugs that have been fiercely litigated in the developing countries during their patent term. This article reviews the outcome of sitagliptin patent litigation and impact on the market exclusivity in some developing countries. This takes the position that the existing conflict between the innovators and generics can be resolved by diluting the misconception that patents on improvement innovations are misuse of patent system or inappropriate extension of patented product life on the part of innovator companies. Whether trivial, simplified or complex, if novel and non-obvious, further improvements in the precursor drugs are patentable within the legal framework of the patent system. The real issue is the scope of monopoly granted to the secondary or follow-on patents. Once the compound patent has expired, follow-on patents on improvements relating to the same compound should not be allowed to use as legal-barrier for the generic medicines entry to the market.

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