On January 17, 2026, the Delhi High Court upheld the rejection of a patent application filed by Hirotsu Bio Science Inc., a Japan-based biotechnology company, for a cancer detection method using nematodes. The Court ruled that the claimed invention constitutes a diagnostic process and is therefore not eligible for patent protection under Indian law.
The judgment affirmed an earlier decision of the Indian Patent Office issued in August 2023, which rejected the application under Section 3(i) of the Indian Patents Act, 1970. This provision excludes diagnostic methods from patentability.
Hirotsu Bio Science Inc. developed a method that uses the nematode Caenorhabditis elegans to detect cancer-related chemical signals in biological samples such as urine. The method evaluates the worms’ chemotactic behavior in response to odours believed to be associated with cancer.
According to the complete patent specification, the company claimed that this approach could identify the presence of cancer with high sensitivity, including at early stages, and described its potential use in clinical settings.
The Assistant Controller of Patents and Designs rejected the application on the ground that it amounted to a diagnostic method. Under Indian patent law, any process that enables the identification of disease status in humans falls outside the scope of patentable subject matter.
Hirotsu Bio Science appealed the decision, arguing that the method functioned only as a screening tool and did not provide a definitive diagnosis. The company also contended that the process was conducted in vitro and did not involve direct medical intervention.
The Delhi High Court rejected these arguments, stating that Indian law does not differentiate between screening and diagnosis if the process determines the presence or absence of disease. The Court observed that the claimed method involved data collection, comparison with reference standards, and inference of disease status, core elements of a diagnostic process.
The Court further clarified that the exclusion under Section 3(i) applies irrespective of whether the method is performed inside or outside the human body or whether it involves automation. The complete specification repeatedly described the invention as capable of diagnosing cancer, which the Court considered decisive.
Delivered in January 2026, the ruling applies across India and reinforces existing judicial interpretations of diagnostic exclusions under the Indian Patents Act. It aligns with prior decisions aimed at preventing exclusive rights over medical diagnostic processes.
The judgment underscores the legal limits on patent protection for diagnostic technologies in India. While innovation in cancer detection continues to advance, diagnostic methods remain excluded to ensure unrestricted access for clinical use and research. Developers may need to rely on alternative intellectual property strategies that do not conflict with statutory exclusions.
(Rh/SS)
