Setting aside the order of refusal of a patent application directed towards a composition of PXD-101 (Belinostat), based on Section 3(d) of the Patents Act, 1970, the Calcutta High Court ruled that Section 3(d) does not apply to the multi-component compositions. The patent application in this case was directed to a composition, not to a salt of PXD-101. Allowing the appeal in Topotarget vs Controller General of Patents and Designs & Ors (SR/12/2020/PT/KOL), the Court clarified that Section 3(d) is only applicable when the invention is a new form of a single known substance or it relates to combinations involving derivatives of a known substance whether alone or with the known substance itself.
Factual Matrix
Topotarget filed a patent application for a composition containing a histone deacetylase inhibitor (HDAC) – specifically PXD101 – combined with a basic in situ salt former, such as arginine or meglumine. The refusal of a patent in this case was based on a pre-grant opposition filed by Fresenius Kabi Oncology. Topotarget filed an appeal challenging the refusal order rejecting its patent application 4712/KOLKNP/2007.
Subject Matter of Patent Application
The invention in the present appeal relates to a pharmaceutical composition for a drug used in cancer treatment. The invention claimed a composition comprised of: (a) A histone deacetylase (HDAC) inhibitor wherein HDACi is a compound of the given formula or a pharmaceutically acceptable salt (active pharmaceutical ingredient and (b) a basic in situ salt former. The salt former comprises arginine or meglumine (inactive ingredient).
Case of the Appellant
The appellant contended that their invention was directed to a composition rather than a salt of PXD-101 (Belinostat). According to the appellant, arginine and meglumine are inactive ingredients and not derivatives of PXD-101. The appellant submitted that the invention as claimed by them was a multi-component composition which fell outside the scope and ambit of Section 3(d) of the Act. The appellant contested that this aspect of the invention was not addressed in the impugned order by the respondent Controller, and it clearly vitiated the finding under Section 3(d) of the Act.
The appellant submitted that the basic in situ salt former increased the solubility of the HDACi PXD101, resulting in a greater amount of the active being used. Explaining the advantages of the claimed composition, the appellant contended that the claimed invention had surprising and unexpected solubility. Other advantages were higher solubility (at higher concentrations of the active HDACi, PXD 101, with no instability), increased stability in a concentrated liquid formulation (for storage), and increased stability in a diluted liquid formulation (when ready for administration).
Respondent Controller’s Reply
The respondent Controller maintained that there were no grounds to interfere with the impugned order. According to the respondent, the finding under Section 10(4) of the Act that the pharmaceutically acceptable salt of solvate as claimed in the invention had not been clearly described was adequately reasoned. The respondent Controller argued that, in the absence of any therapeutic efficacy, the invention was contrary to Section 3(d) of the Act. According to the respondent, this aspect was critically and strictly analysed, and was in line with the Supreme Court’s ruling in Novartis AG vs Union of India (2013) 6 SCC 1.
Court’s Analysis and Findings
On the Role of the Examiner
The Court found that Respondent No. 2 had overlooked the clearly defined and limited role of an Examiner under the scheme of the Patents Act. According to the Court, the duty of the Examiner in discharging its statutory functions was limited only to making a report to the Controller. They are not entitled to participate or make submissions during the hearings of the proceedings. The Controller, according to the Court, was obliged to apply their mind independently to the objections and submissions made and adjudicate the matter and not merely endorse the Examiner’s opinion. The Court also questioned the Controller’s reliance on newly cited prior art documents that were not cited in the First Examination Report.
On Technical Advancement
The Court looked at Section 2(1)(ja) and observed that on a plain reading of this provision, an invention should provide technical advancement to the already existing knowledge having economic significance which should not be obvious. The Court found that in the present case, it was the agreed position that the compound “PXD-101” is a known ingredient. The Court agreed with the appellant that they did not claim PXD-101 or HDACi. According to the Court, the invention claimed to provide a composition of two elements, viz., an active component and an inactive component that is an in-situ salt former. This means appellant’s invention was an engineered pharmaceutical composition comprising PXD-101, an HDAC inhibitor, a known substance, but the inventive step lies in identifying the specific basic in situ salt formers, namely arginine and meglumine. The Court found that, in the impugned order, this aspect was not addressed by the respondent Controller, thereby clearly vitiating the Controller’s findings.
On the Mosaic of Prior Art
The Court found that the respondent Controller’s finding of obviousness was driven by hindsight reconstruction rather than appreciation of the cited prior arts. The Court noted that it was well settled that a combination of multiple documents is permissible only where the prior art itself provides a clear lead or motivation to combine their teachings. This requires a coherent technical thread linking the cited prior art to the claimed invention. In such circumstances, the finding of obviousness and applicability of the prior art is unsustainable and requires reconsideration. [Guangdong Oppo Mobile Telecommunications Corp. Ltd. vs Controller of Patents and Designs 2023 SCC OnLine Cal 6650].
The Court agreed with the appellant that a hindsight reconstruction by using the patent in question as a guide through the maze of prior art references in the right way to achieve the result of the claim was to be avoided. It cited the Court’s well-settled ruling of the Courts in Groz-Beckert KG vs Union of India & Ors. [2023 SCC OnLine Cal 111] and Takeda Pharmaceutical Co. Ltd. vs Controller of Patents and Designs & Ors. [2025 SCC OnLine Cal 3105] in support of this proposition. The Court ruled that in the present case, the finding of obviousness and applicability of the prior art were unsustainable and required reconsideration.
On the Applicability of Section 3(d)
According to the Court, Section 3(d) was not applicable as the appellant’s invention was directed towards a composition and not a salt of PXD-101. Arginine and meglumine are inactive ingredients and not derivatives of PXD-101. The Court ruled that the invention was claimed as a multi-component composition and therefore it fell outside the scope and ambit of Section 3(d) of the Act. The Court noted that this aspect of invention was not even dealt with by the respondent Controller in the impugned order and ruled that it clearly vitiated the finding of the Controller under Section 3(d) of the Act.
Decision of the Court
The Court ruled that the impugned order, with many infirmities, was unsustainable and set it aside, allowing the appeal. The Court remanded the matter and directed that it be heard and decided afresh by a different Controller, in accordance with the law, after affording all parties a right of hearing. The Court made clear that there had been no expression on the merits of the case, and all questions were left open to be adjudicated upon afresh.
Concluding Remarks
Section 3(d) of the Patents Act, 1970, remains a matter of interpretation in the judicial proceeding. Its applicability and reach have been tested in many appellate cases, starting with the Supreme Court case in Novartis. In the present case, the Court concluded that Section 3(d) does not apply to inventions that involve multi-component compositions. The implications of this decision could significantly influence how similar cases are approached in the future, particularly in defining the criteria for patentability concerning multi-component composite inventions.
Author: DPS Parmar (Special Counsel)