By Jigyasa Pareek

In Hirotsu Bio Science Inc. vs Assistant Controller of Patents and Designs [C.A.(COMM.IPD-PAT) 45/2023], the Delhi High Court upheld the refusal of patent application number 201617022947, entitled “Cancer Detection Method Using Sense of Smell of Nematode”, holding that an in vitro cancer detection process employing the olfactory responses of nematodes falls within the exclusion under Section 3(i) of the Patents Act, 1970.

The subject application related to a method of detecting cancer using the chemotaxis and olfactory responses of nematodes, particularly C. elegans, to biological samples derived from a subject. The invention claimed that nematodes exhibited attraction towards samples from cancer patients and avoidance towards samples from healthy individuals.

The application was refused on the ground that the claimed invention constituted a non-patentable diagnostic method under Section 3(i).

Before the Court, the Appellant argued that the invention merely involved detection and not diagnosis. According to the Appellant, the method only generated an indicator of cancer risk by examining biological samples outside the human body and did not involve clinical interpretation, physician judgment, or treatment decisions.

The Appellant emphasised that the claims were expressly confined to in vitro detection methods, and that the complete specification which referred to “diagnosis” for the purpose of merely providing contextual understanding to a PSITA could not be used to expand the scope of the claims. It was contended that the claims, and not descriptive passages in the specification, define the scope of protection.

Reliance was placed on decisions such as EMD Millipore vs Controller, F. Hoffmann-La Roche vs Cipla, and Chinese University of Hong Kong vs Controller to argue that processes merely generating information relevant to diagnosis do not come under the  purview of Section 3(i), and that the expression “diagnostic” should be restricted to in vivo processes.

The Court reaffirmed that Section 3(i) excludes both in vivo and in vitro diagnostic methods, noting that the provision does not contain the expression “practised on the human or animal body”. Relying upon Chinese University of Hong Kong, Natera vs Controller, and Sequenom vs Controller, the Court held that the absence of such qualifying language reflects a broader statutory exclusion. Further, the Court noted that a screening test capable of identifying a disease may still qualify as “diagnostic” under Section 3(i), even if definitive tests may subsequently be undertaken.

The Court examined the complete specification to ascertain the true nature of the invention and observed that the specification repeatedly described the invention as a cancer diagnosis system capable of detecting even early-stage cancers with high sensitivity and specificity. The Court observed that the invention involved collection of samples, analysis of responses, comparison with established indicators, and derivation of a conclusion regarding the presence of cancer. Such a process was held to possess the essential attributes of diagnosis.

Rejecting the Appellant’s attempt to distinguish detection from diagnosis, the Court held that the claimed process effectively identified the presence of a disease, namely, cancer. It also noted that the provision includes both positive and negative diagnoses.

Further, rejecting the Appellant’s contention that diagnosis necessarily requires skills or clinical judgment, the Court observed that “it is immaterial who performs the method”. It held that Section 3(i) cannot be confined only to methods practised by medical professionals, as such an interpretation would permit methods independently arriving at diagnostic conclusions to escape the statutory exclusion.

The Appellant’s submission that claims alone should determine patent eligibility was also rejected. The Court held that while claims delimit the monopoly, the complete specification can and should be examined to determine whether the claimed process is, in substance, diagnostic in nature.

The Court found that the amended attempt to characterise the results merely as supporting preliminary screening rather than definitive diagnosis could not overcome the exclusion, particularly when the specification itself attributed extremely high diagnostic accuracy to the claimed process.

Independent claim 5, directed to identifying olfactory receptors in nematodes, was also held unpatentable since it constituted a preparatory step integrally connected with the diagnostic method claimed in claim 1 and lacked independent utility in isolation. Likewise, independent claim 10, directed towards identifying cancer types, was found inseparable from the underlying cancer detection method and consequently fell alongside claim 1 under Section 3(i).

Upholding the Controller’s reasoning, the Delhi High Court dismissed the appeal and affirmed that in vitro processes which, in substance, accurately identify the presence of disease would fall within the diagnostic exclusion under Section 3(i), regardless of whether further confirmatory tests may subsequently be undertaken.