Delhi High Court Upholds Rejection of Patent for Innovative Worm-Based Cancer Detection Method

Introduction

In a significant ruling for biotechnology and intellectual property law, the Delhi High Court has dismissed an appeal by Japanese firm Hirotsu Bio Science Inc. against the rejection of its patent application for a novel cancer detection method utilizing the olfactory senses of nematodes (tiny worms). Justice Tejas Karia, in his judgment dated January 17, 2026, upheld the Patent Office's order under Section 3(i) of the Indian Patents Act, 1970, which prohibits the patenting of methods for diagnosing diseases in humans or animals. This decision reinforces India's stringent approach to patent eligibility in the medical field, emphasizing that even in vitro (outside the body) diagnostic processes fall within the statutory exclusion. The case, Hirotsu Bio Science Inc. v. Assistant Controller of Patents and Designs (C.A.(COMM.IPD-PAT) 45/2023), highlights ongoing tensions between innovation in biotech diagnostics and public policy safeguards against monopolizing essential healthcare tools. The bench, comprising solely Justice Karia, scrutinized the invention's claims and specifications, concluding that the method constitutes a diagnostic process despite the appellant's arguments to the contrary. This outcome could influence future patent applications in early cancer screening technologies, particularly those relying on biological indicators.

Case Background

The dispute traces back to July 4, 2016, when Hirotsu Bio Science Inc., a Japanese biotechnology company, filed a national phase patent application (No. 201617022947) in India, stemming from a PCT application dated December 10, 2014. Titled "Cancer Detection Method Using Sense of Smell of Nematode," the invention leverages the chemotaxis—the movement response—of the nematode Caenorhabditis elegans to odors in human biological samples, such as urine. The nematodes reportedly exhibit attraction to cancer-specific scents, enabling detection of various cancers, including early-stage ones like gastric, colon, rectal, and pancreatic, with claimed accuracy rates up to 100% in initial tests.

The Patent Office, Delhi, issued a First Examination Report (FER) on August 19, 2020, raising objections under Sections 2(1)(j), 3(i), 3(j), and 10(4) of the Patents Act, primarily citing non-patentability due to the diagnostic nature of the method. Hirotsu responded on December 28, 2020, with revised claims narrowing the scope to "in vitro" processes and emphasizing detection over diagnosis. Hearings were scheduled for April 11, 2023, following adjournments, during which the appellant advanced oral and written submissions, including further claim amendments.

On August 29, 2023, the Assistant Controller rejected the application outright, holding that the claims violated Section 3(i), which excludes "any process for the medicinal, surgical, curative, prophylactic, diagnostic, therapeutic or other treatment of human beings or any process for a similar treatment of animals." Aggrieved, Hirotsu appealed under Section 117A of the Act to the Delhi High Court, arguing that the method was a mere screening tool, not a clinical diagnosis. The appeal hearing focused on interpreting the scope of "diagnostic" under Section 3(i), whether it encompasses in vitro methods, and the role of the patent specification in defining claim boundaries. The case timeline underscores the protracted nature of patent examinations in India, especially for biotech inventions intersecting public health.

The parties involved included Hirotsu Bio Science Inc. as the appellant, represented by advocates Kshitij Saxena, Saransh Vijayvargiya, and Daksh Oberoi. The respondent, the Assistant Controller of Patents and Designs, was represented by Manisha Agarwal and Nipun Jain. No external interveners or amici participated, keeping the focus on statutory interpretation.

Arguments Presented

Hirotsu Bio Science mounted a robust defense, contending that its invention was fundamentally a detection mechanism, not a diagnostic one under Section 3(i). The appellant's counsel emphasized that the method operated entirely in vitro—analyzing nematode responses to ex vivo biological samples like urine—without involving clinical judgment, medical interpretation, or intervention on the human body. They drew an analogy between the patent specification (a "genus" providing broad context) and the claims (a "species" limited to detection), arguing that references to "diagnosis" in the specification were illustrative, not definitional. Claim 1, for instance, was highlighted as focusing on nematode chemotaxis as an indicator for cancer risk, signaling presence versus absence without specifying type or requiring physician input.

The appellant relied on precedents like EMD Millipore Corporation v. Assistant Controller of Patents and Designs (2025:DHC:8928), asserting that Section 3(i) targets methods involving professional medical judgment or bodily intervention, not autonomous lab processes. They also cited Chinese University of Hong Kong and Sequenom, Inc. v. Assistant Controller of Patents and Designs (2023 SCC OnLine Mad 6372), arguing that "diagnostic" should be confined to in vivo processes or those inherently identifying diseases without further testing. Hirotsu pointed to its commercial product, N-NOSE®, already marketed in Japan as a risk indicator, not a definitive diagnosis, and stressed the invention's utility in early screening without monopolizing treatment. Amendments to claims, such as adding language that results serve as "supporting documentation for preliminary screening," were proposed to underscore non-diagnostic intent.

In opposition, the Assistant Controller argued that the method squarely fell within Section 3(i)'s prohibition, which applies to both in vivo and in vitro processes without textual distinction. The respondent's counsel invoked the plain language of the section, cautioning against judicial addition of qualifiers like "in vivo" (citing Union of India v. Hansoli Devi , (2002) 7 SCC 273). They dissected the claims as encompassing all hallmarks of a diagnostic process: data collection (sample preparation), comparison (nematode response against standards), deviation identification (attraction versus avoidance), and attribution to a clinical picture (cancer presence or risk). Even Claim 5—identifying olfactory receptors—was deemed a preparatory step integral to the diagnostic chain, useless in isolation.

The respondent countered the detection-diagnosis distinction by noting that high accuracy (up to 100% in specifications) rendered it diagnostic, regardless of performer. Precedents like Natera Inc. and Anr. v. Assistant Controller of Patents and Designs (2025:DHC:8937) and Sequenom Inc. & Anr. v. Controller of Patents (2025:DHC:8926) were cited to argue that screening tests identifying pathologies, even preliminarily, qualify as diagnostic if they reduce the need for further invasive tests. The specifications' explicit references to "cancer diagnosis system" and detection of early-stage cancers were highlighted to show inconsistency with amended claims, preventing a narrow reading. Ultimately, the respondent urged upholding the rejection to safeguard public access to diagnostic innovations.

Legal Analysis

Justice Karia's reasoning centered on a harmonious interpretation of Section 3(i), balancing innovation incentives with public policy against patenting core medical practices. The court affirmed that the exclusion applies unequivocally to both in vivo and in vitro methods, as the statute's text lacks qualifiers found in counterparts like Article 52(4) of the European Patent Convention. Drawing from Chinese University of Hong Kong (supra), the judge noted (at para 30) that the absence of "practised on the human or animal body" extends "diagnostic" to lab-based processes capable of uncovering pathologies.

The analysis dissected the invention's complete specification, revealing its dual portrayal: while claims emphasized "detection," the description portrayed a "cancer diagnosis system" detecting early cancers with near-perfect sensitivity and specificity (paras [0028], [0030]). This led to the conclusion that the process involves diagnostic steps—examination, comparison, deviation finding, and attribution—mirroring explanations in Natera Inc. (supra, para 79). The court rejected the appellant's genus-species analogy, holding that specifications contextualize claims; one cannot disclaim descriptive admissions of diagnostic utility ( Chinese University , para 50).

Precedents played a pivotal role. In Sequenom Inc. (supra, paras 100-101), a similarly accurate in vitro test was deemed diagnostic for confirming or ruling out conditions, defeating Section 3(i)'s purpose. Natera Inc. clarified that while diagnostic tools (e.g., devices) may be patentable, processes monopolizing diagnosis manners (e.g., swab tests) are not, irrespective of in vitro nature. The court distinguished EMD Millipore , limiting it to non-diagnostic lab aids, and dismissed Chinese University 's para 51 (on non-diagnostic indicators) as inapplicable, given the invention's standalone accuracy obviating further tests ( Chinese University , para 45: screening qualifies if identifying disease, albeit confirmable).

Justice Karia addressed the "who performs" immateriality, warning that autonomy doesn't evade exclusion; otherwise, AI-driven diagnostics could be patented, undermining policy. Proposed amendments (e.g., "preliminary screening") were futile, as specifications contradicted by touting high-accuracy diagnosis. Other cases like F. Hoffmann-La Roche Ltd. v. Cipla Ltd. (2015:DHC:9674-DB) reinforced claims' plain meaning but subordinate to specifications' context. This holistic approach underscores Section 3(i)'s broad shield for healthcare accessibility, prioritizing societal benefit over individual monopoly.

Key Observations

The judgment is replete with incisive observations illuminating the court's stance:

• On the scope of Section 3(i): "Section 3(i) excludes both in vivo and in vitro methods. In its plain reading, the provision does not qualify any of the exclusions with the phrase 'in vivo' or 'in vitro'. As a general proposition of law, it is well settled that one is not ordinarily permitted to add or delete words from the statute." (Para 10, quoting Impugned Order, citing Union of India v. Hansoli Devi ).

• Distinguishing detection from diagnosis: "The Appellant submitted that the detection methods differ significantly from diagnostic methods. Diagnostic methods require the skill and knowledge of the physician or surgeon to analyze and interpret symptoms, while in the case of detection, the result is not accompanied by a discussion... This Court is of the view that it is immaterial who performs the method." (Para 35).

• On specification's role: "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." (Para 33).

• Precedent application: "If the screening test identifies the disease, disorder or condition albeit subject to confirmation by definitive tests, it would still qualify as 'diagnostic' for purposes of Section 3(i) because the provision does not use the qualifier 'definitive.'" (Para 32, quoting Chinese University , para 45).

• Policy rationale: "It would be challenging if this section is kept limited to only methods practiced by medical practitioners as the application would be patentable even if the method would be completely autonomous." (Para 35).

These excerpts encapsulate the judgment's emphasis on textual fidelity and public policy.

Court's Decision

The Delhi High Court unequivocally dismissed the appeal, upholding the Assistant Controller's Impugned Order dated August 29, 2023. Justice Karia ruled: "The Appeal is dismissed and the Impugned Order dated 29.08.2023 is upheld." (Para 40). No costs were imposed, but the decision quashes any prospect of patent grant for the subject application.

Practically, this bars Hirotsu from exclusive rights in India, allowing open use of the nematode-based method, aligning with Section 3(i)'s aim to prevent healthcare monopolies. For future cases, it sets a precedent that in vitro diagnostics, if accurately identifying diseases without needing extensive confirmation, are unpatentable—impacting biotech firms eyeing India's market. This may deter similar applications unless claims strictly limit to non-diagnostic tools (e.g., receptor identification in isolation), while encouraging product patents for kits or devices ( Natera Inc. , para 79(e)). Broader implications include reinforcing India's pro-access stance in global pharma, potentially spurring compulsory licensing discussions ( Chinese University , para 52), but challenging innovators to navigate exclusions. As biotech advances (e.g., AI diagnostics), legislative tweaks may be needed to balance incentives without compromising affordability. Overall, the ruling prioritizes public health, ensuring worm-based screening remains accessible amid rising cancer burdens.