The Delhi High Court’s decision in Geron Corporation vs The Assistant Controller of Patents and Designs [C.A.(COMM.IPD-PAT) 244/2022] represents another important development in the growing body of jurisprudence on Section 3(i) of the Patents Act, 1970. Building upon the principles laid down in Chinese University of Hong Kong, Natera, and Sequenom, the Court considered whether an invention framed as an “in vitro screening method” for identifying cancer patients likely to benefit from telomerase inhibitor therapy could escape the exclusion relating to diagnostic methods. The decision underscores that the characterisation of a claim as a “screening” method is not determinative; rather, the inquiry must focus on the substance of the claimed process and the role it plays in clinical decision-making.

The appeal arose from the refusal of patent application number 4506/DELNP/2015, entitled “Diagnostic Markers for Treating Cell Proliferative Disorders with Telomerase Inhibitors”. The application related to the use of telomere length as a biomarker to identify patients who were likely to benefit from treatment with telomerase inhibitors such as imetelstat. The amended independent claim 1 was directed to an in vitro screening method for selecting an individual diagnosed with or suspected of having cancer who would benefit from telomerase inhibitor treatment, based upon determining whether the patient’s relative telomere length fell within a specified percentile threshold.

The Controller refused the application on the ground of non-patentability under Section 3(i). Having concluded that the claims were directed to a non-patentable diagnostic method related to cancer treatment, the Controller expressly declined to assess the remaining objections relating to inventive step and Section 3(d). The refusal proceeded on the basis that the claimed method involved analysing a patient’s biological sample, determining telomere length and selecting patients for telomerase inhibitor therapy on the basis of that analysis. The Controller further relied upon the original PCT claims to conclude that the invention, in substance, was directed towards diagnosis and treatment of cancer, and observed that the subsequent introduction of expressions such as “in vitro screening method” did not alter the nature of the claimed subject matter.

Before the Court, the Appellant argued that:

• The claimed invention did not diagnose cancer but merely operated upon individuals already diagnosed with, or suspected of having, the disease to determine whether they were likely to benefit from a particular therapy.
• The claimed method neither identified the existence of disease nor determined its nature or severity, and that telomere length functioned only as a predictor of treatment response rather than a diagnostic marker.
• The Controller had erroneously relied on illustration 6 of the Biotechnology Guidelines, which treats biomarker-based monitoring of a patient’s response to drug therapy as a diagnostic method falling within Section 3(i). According to the Appellant, that illustration concerned post-treatment monitoring, whereas the claimed invention involved pre-treatment patient selection.
• Patentability ought to have been assessed exclusively on the amended claims pending in the Indian national phase, without reference to the original PCT claims.
• Corresponding patents had been granted in other jurisdictions, supporting the Appellant’s contention that the invention ought to be considered patentable.

The Controller maintained that the invention was, in substance, a diagnostic method related to cancer treatment. It was argued that since the claimed process guided therapeutic intervention, it squarely fell within Section 3(i).

Before examining the merits of the exclusion under Section 3(i), the Court addressed the Appellant’s objection to the Controller’s reliance on the Biotechnology Guidelines. Rejecting the contention, it observed that the Guidelines, though not having statutory force, are intended to promote consistency and uniformity in examination practice and may legitimately guide Controllers unless shown to be contrary to the Act. Simultaneously, however, the Court cautioned that the Guidelines must evolve with judicial and technological developments. That is a fairly significant observation because it gives the Guidelines practical legitimacy while also recognising their limitations.

The Court also referred to the Delhi High Court’s recent decisions in Chinese University of Hong Kong, Natera and Sequenom. From these authorities, the Court distilled several principles, including that:

• the expression ‘diagnostic’ ought to be understood in the context of diagnosis for treatment of human beings, and must not extend to every test that may have some medical relevance;
• a process need not itself establish the existence of a disease to be considered diagnostic. The key enquiry is whether its outcome contributes to a medical practitioner’s treatment-related decision-making;
• Section 3(i) draws no distinction between in vivo and in vitro diagnostic methods;
• the inquiry must focus on the substance of the claims and specification rather than drafting labels;
• the test is whether the claimed process is inherently capable of enabling a diagnosis for treatment when evaluated by a person skilled in the art, including a medical professional, in light of the claim language and the results generated by the process;
• a diagnosis need not conclusively establish pathology. Even a process that supports or informs a diagnosis requiring subsequent confirmation may fall within Section 3(i);
• A screening method may still be regarded as diagnostic if it identifies a disease, condition, or clinically relevant aspect thereof for treatment purposes;
• processes that contribute to medical treatment decisions may be excluded even if they do not independently establish disease;
• what is excluded is the diagnostic process itself, such as methods used in carrying out examinations or tests in clinical practice;
• diagnostic products, instruments, kits, and devices remain patent-eligible; and
• as per the Biotechnology Guidelines, biomarker-based methods used to monitor a patient’s response to therapy constitute diagnostic methods.

The Court also endorsed the decision in Sequenom, where it had been held that even methods yielding a “negative diagnosis” or eliminating the need for further testing may attract Section 3(i) if they influence medical decision-making.

Applying these principles, the Court examined the claims and the specification.

The Court noted that the claimed method essentially comprised two steps: first, determining relative telomere length in cancer cells obtained from a patient’s biological sample; and second, selecting patients for telomerase inhibitor treatment if their telomere lengths fell at or below the 50^th percentile of an established standard. In the Court’s view, the outcome of the analysis formed the basis for determining whether a patient should receive the therapeutic intervention.

The Court also found it significant that the Controller had compared the amended claims with the original PCT claims and subsequent amendments, agreeing that the insertion of expressions such as “in vitro screening method” merely altered the language of the claims without changing their substantive effect. The invention remained directed towards identifying cancer patients who should receive telomerase inhibitor treatment.

Accordingly, the Court held that, in practical terms, the claimed process formed an integral part of treatment decision-making and therefore constituted a diagnostic process excluded under Section 3(i). It also rejected the Appellant’s reliance on foreign grants, reiterating that patentability in India must be assessed in accordance with the Patents Act and its unique exclusions.

Finding no infirmity in the Controller’s reasoning, the appeal was accordingly dismissed.