Pharmacyclics Continues the Divisional Applications Debate in India

Summary: The Calcutta High Court’s ruling in the Pharmacyclics case clarifies that a divisional patent application can be filed as long as the invention is disclosed in the full specification, even if it was not included in the original claims.

Introduction

In 2024, the Indian Patent Office (“IPO”) issued the Patents (Amendment) Rules, 2024 (“Rules”), which, among other things, amended the rules relating to filing of divisional applications. Specifically, the Rules clarified that a divisional application could be filed based on the subject matter disclosed either in the provisional specification or the complete specification, as opposed to only based on the claims. These Rules implemented the decision of the Delhi High Court in Syngenta Ltd. v. Controller of Patents (2023:DHC:7473-DB).

The present note discusses the more recent decision of the Calcutta High Court in Pharmacyclics LLC v. Deputy Controller of Patents & Designs (I.P.D.P.T.A. No. 4 of 2024, decision dated 2 September 2025), which has held that a divisional application is an independent application and will not be affected by the proceedings of the parent application.

Background

The appellant, Pharmacyclics LLC, had filed Indian Patent Application No. 3985/KOLNP/2012 initially directed to methods of treating hematological malignancies using BTK inhibitors. The claims were later amended to a compound (ibrutinib) for treating relapsed or refractory non-Hodgkin’s lymphoma. In 2018, the appellant filed a divisional application (Indian Application No. 201838043708) claiming a combination of ibrutinib with anti-CD20 antibodies (rituximab or ofatumumab).

The IPO rejected the divisional application on the grounds:

1. The parent application had 133 claims directed to a method for treating haematological malignancies. These were later amended to 33 product claims, directed to a single product. When filing the divisional application, the claims were changed to combination claims, which were beyond the scope of the originally-filed claims (PCT claims) and the amended claims. Thus, the amended claims filed with the divisional application could not be allowed under Section 59 (1) of the Patents Act, 1970 (the “Act”).
2. The applicant failed to stipulate the nature or reason for the amendment. Thus, the amended claims in the divisional application were not allowed under Section 57(2) of the Act.

The Calcutta High Court’s Analysis

1. No objection to divisional application in the First Examination Report (“FER”): The Court noted that the Controller had not raised any objection on the maintainability of the divisional application in the FER. In fact, the Controller had held that the claims of the divisional application are fully supported by claim 33 of the parent application.

2. Maintainability of divisional applications: The Court clarified that a divisional application is maintainable if:
   1. Its claims are based on the disclosure in the complete specification; and
   2. There is no overlap between the claims of the parent and the divisional application

   Importantly, the Court emphasized that it is not necessary for a divisional application to be based only on the original PCT claims filed in the parent application.

3. Independence of divisional applicationsRelying on Section 16(3), the Court held that once a divisional application is recognized, it must be treated as a substantive application, independent of the parent. Thus, the outcome of the parent does not have any bearing on the examination of the divisional application. The Court concluded that the Controller had erred in rejecting the divisional application by relying on the claims of the parent application.

4. Amendments and Section 59
   The Court pointed out that the divisional application itself had not undergone amendments, and thus, objections under Section 59 were misplaced. It reiterated that so long as claims are supported by the specification, amendments (or new claim sets in a divisional application) are permissible.

5. No conflict between the claims of patent and the divisional
   The Court held that there was no conflict between claim 1 of the divisional (a combination of two actives) and claim 33 of the parent (a compound of Formula D).

6. Technical contribution and inventiveness
   Finally, the court observed that Pharmacyclics had demonstrated that combining ibrutinib with anti-CD20 antibodies reduced infusion-related reactions and improved efficacy. These unexpected results constituted technical advancement and supported inventiveness, reinforcing the patentability of the combination.

In its findings, the Court held that the divisional application filed by Pharmacyclics, although not divided out of the parent application’s amended claims, was valid because the combination therapy was disclosed in the specification. Thus, the Court set aside the Controller’s order and remanded the divisional application for fresh examination by a different Controller.

Conclusion

The Pharmacyclics decision has clarified that the divisional application must be treated as an independent application, distinct from its parent. Further, it has reiterated that a divisional application need not be carved out from the claims of the patent application including the PCT claims, reinforcing the rights of applicants to pursue legitimate embodiments disclosed in their specifications via a divisional application. For practitioners, the decision underscores the importance of drafting comprehensive specifications and strategically using divisional applications to protect different facets of an invention.