Introduction

In a procedurally instructive decision closed March 18, 2024, Canada’s Intellectual Property Office (CIPO) Patent Appeal Board issued its recommendation regarding Canadian patent application CA2889826A1, filed by inventor Emmanuel E. Egom and represented by Borden Ladner Gervais LLP. The case centered on methods of treating pulmonary hypertension through activation of the natriuretic peptide receptor C (NPR-C) signaling pathway — a biologically targeted therapeutic approach with significant clinical implications.

The Board’s recommendation illustrates a nuanced patentability analysis under the Canadian Patent Act, ultimately finding that a third set of proposed claim amendments satisfied compliance requirements. For patent practitioners navigating pharmaceutical and biologic prosecution before CIPO, this case offers concrete procedural and strategic guidance on claim clarity, sufficient disclosure, and the iterative amendment process under subsection 86(11) of the Patent Rules.

The outcome underscores a broader principle: strategic claim refinement, rather than adversarial contest, can resolve patentability objections efficiently — a lesson directly applicable to R&D-driven biotech and pharmaceutical patent portfolios.

Case Overview

The Parties

The Patent at Issue

This matter concerned Canadian patent application CA2889826A1, which focuses on:

• • **Application No.:** CA2889826A1
• • **Technology Area:** Biopharmaceutical / Cardiovascular Therapeutics
• • **Subject Matter:** Methods of treating pulmonary hypertension through administration of natriuretic peptide receptor C (NPR-C) signaling pathway activators.

NPR-C is a receptor subtype involved in regulating vascular tone and fluid homeostasis. The claimed methods represent a targeted pharmacological approach to pulmonary arterial hypertension (PAH), a life-threatening condition with limited treatment options. The patent claims cover therapeutic methods rather than a specific compound, implicating method-of-treatment patentability considerations central to pharmaceutical patent prosecution in Canada.

Litigation Timeline & Procedural History

This matter proceeded through CIPO’s Patent Appeal Board review process — a non-adversarial, administrative tribunal mechanism distinct from federal court litigation.

Key Procedural Milestones:

• • The Board issued a **Preliminary Review letter** analyzing proposed claims set-2 (claims 1–24), identifying compliance issues under subsection 27(3) and 27(4) of the Patent Act and section 60 of the Patent Rules.
• • The applicant responded with **proposed claims set-3** (claims 1–20) via a letter dated **February 29, 2024**.
• • The Board issued its **final recommendation on March 18, 2024**, the date the matter was closed.

The streamlined timeline reflects efficient prosecution through the Board’s review mechanism. Notably, BLG’s decision not to contest the Board’s preliminary determinations regarding set-2 — and instead submit a refined set-3 — proved strategically decisive, accelerating resolution without protracted disagreement.

The Verdict & Legal Analysis

Outcome

The Patent Appeal Board recommended that the applicant be notified, pursuant to subsection 86(11) of the Patent Rules, that replacement of the claims on file with proposed claims 1 to 20 (as submitted February 29, 2024) constitutes a necessary amendment for compliance with the Patent Act and Patent Rules. The matter was classified as closed, with a base of termination categorized as “Unpatentable” under the original claims — resolved prospectively through the compliant amended claims.

No damages or injunctive relief were applicable, consistent with the administrative nature of this proceeding.

Verdict Cause Analysis: Claim-by-Claim Compliance

Proposed Claims Set-2 (Claims 1–24) — Partially Deficient

The Board’s Preliminary Review identified the following regarding set-2:

• • **Subsection 27(3) (Sufficient Disclosure) and Section 60 (Support):** Claims 1–4, 7–14, and 16–23 were found to be sufficiently disclosed and fully supported by the description — a meaningful finding validating the underlying specification’s robustness.
• • **Subsection 27(4) (Definiteness):** Claims 1, 2, 13, and 22 were found definite. However, **claims 3, 4, 14, and 23 lacked clear differentiation** from claims 5, 6, 15, and 24, respectively. This overlap created indefiniteness — a fundamental deficiency under Canadian patent law requiring that each claim define a clear and distinct scope of protection.

The indefiniteness finding is legally significant. Under subsection 27(4), claims must distinctly and explicitly define the subject matter. Where two claims fail to establish differentiated scope, both claims risk invalidity, and prosecution cannot proceed without resolution.

Proposed Claims Set-3 (Claims 1–20) — Fully Compliant

Rather than arguing the sufficiency of the differentiation in set-2, BLG adopted a targeted surgical approach: **deleting claims 3, 4, 14, and 23** from set-2 entirely to eliminate the overlap. The resulting set-3, comprising 20 claims, was found by the Board to:

• • Comply with subsection 27(4) (definiteness);
• • Remain compliant with all other provisions of the Patent Act and Patent Rules.

The Board agreed that set-3 “addresses the clarity issue” — a concise but authoritative affirmation that the amendments were both necessary and sufficient.