Delhi High Court Upholds Rejection of Japanese Firm's Patent Bid For Worm-Based Cancer Detection

In a judgment delivered on January 17, 2026, a Single-Judge Bench of Justice Tejas Karia dismissed the appeal filed by Hirotsu Bio Science Inc., holding that the company's cancer detection method amounts to a diagnostic process barred from patent protection under Section 3(i) of the Patents Act, 1970.

The Court observed that “the Complete Specification of the Subject Application provide that the process sought to be patented is not limited to just a screening process for diagnosing cancer before it happens, but it also is a general diagnosing method for cancer. Therefore, the invention claimed in Subject Application would fall under the Section 3(i) of the Act.”

Hirotsu's patent application related to an invention titled “Cancer Detection Method Using Sense Of Smell Of Nematode,” which proposed detecting cancer by analysing the smell-based responses of worms when exposed to biological samples such as urine and tissue specimens. According to the company, the method merely indicated cancer risk and did not involve diagnosis or treatment and was therefore patentable.

The Patent Office however rejected the application in August 2023, holding that the claimed process involved collection of data, comparison with standard values and drawing conclusions regarding the presence of cancer, thereby satisfying all stages of a diagnostic method and falling squarely within the statutory exclusion under the Patent Act.

Challenging the rejection before the Court, Hirotsu argued that its invention was limited to laboratory-based detection conducted outside the human body and therefore could not be excluded from patentability as a diagnostic process. It further submitted that diagnosis requires medical expertise, whereas its method merely produced an objective laboratory result.

The Patent Office opposed the appeal, pointing to the complete specification, which described the invention as a “cancer diagnosis system” capable of detecting early-stage cancer with high accuracy. It was submitted that the invention, by its own description, led to a medical conclusion regarding the presence of cancer.

After examining the claims alongside the complete specification and relevant judgments, the Court agreed with the Patent Office and held that the method, as claimed, was capable of identifying cancer and therefore qualified as a diagnostic process.

Referring to the earlier rulings in Chinese University of Hong Kong and Sequenom, Inc. v. The Assistant Controller of Patents and Designs and Natera Inc. and Anr. v. Assistant Controller of Patents and Designs, the Court reiterated that screening and detection methods also fall within Section 3(i) if they uncover a disease or medical condition.

Holding that the claimed invention was non-patentable despite performing cancer detection on samples and not on the human body, the Court observed, “Section 3(i) of the Act does not differentiate between the in vivo and in vitro processes.”

Rejecting the argument that the exclusion applies only when diagnostic method is performed by a medical practitioner, the Court observed that, “it is immaterial who performs the method.”

Consequently, the Court upheld the rejection of the patent application and dismissed the appeal filed by Hirotsu Bio Science Inc.

For Appellant: Advocates Kshitij Saxena, Saransh Vijayvargiya & Daksh Oberoi.

For Respondent: Advocates Manisha Agarwal & Nipun Jain.