CNIPA Invalidates Tofacitinib Sustained-Release Patent Over Lack of Inventive Step
核心洞察
The China National Intellectual Property Administration (CNIPA) invalidated a patent for tofacitinib oral sustained-release dosage forms on October 9, 2025, finding all claims lacked inventive steps.
The patent covered once-daily formulations containing 11 mg or 22 mg of tofacitinib with specific osmotic delivery system components for treating rheumatoid arthritis patients.
CNIPA's decision highlights critical challenges in pharmaceutical formulation patents, particularly when technical effects cannot be clearly established from patent specifications.
The China National Intellectual Property Administration (CNIPA) has invalidated a pharmaceutical formulation patent for tofacitinib sustained-release tablets, marking a significant development in Chinese patent law for drug delivery systems. On October 9, 2025, CNIPA issued Invalidation Decision No. 588549, declaring the invention patent titled "Tofacitinib oral sustained release dosage forms" invalid in its entirety due to lack of inventive steps.
Patent Details and Clinical Context
Tofacitinib is a JAK3 (搜索) (Janus kinase 3) inhibitor primarily used for clinical treatment of patients with moderate to severe active rheumatoid arthritis who are intolerant to or do not respond well to methotrexate. The invalidated patent specifically related to a tofacitinib sustained-release tablet formulation designed for once-daily administration.
The patent's main claim described a pharmaceutical dosage form comprising a core containing 11 mg or 22 mg of tofacitinib with sorbitol accounting for 60-85% by weight of the dosage form. The formulation featured a semi-permeable membrane coating weighing about 5-10% of the core, consisting essentially of cellulose acetate and hydroxypropyl cellulose in a 6:4 weight ratio, with at least one delivery port diameter of 100-1,000 μm.
Invalidation Grounds and Evidence Analysis
The invalidation petitioner challenged the patent's validity on multiple fronts, including amendments exceeding original disclosure scope, insufficient specification disclosure, claims not supported by the specification, and lack of inventive steps. CNIPA ultimately supported the invalidation based solely on the finding that all claims lacked inventive steps.
In an unusual approach, the invalidation decision used a combination of five pieces of literature to assess the inventive step of Claim 1. Evidence 6 served as the closest prior art, relating to development of a single-layer osmotic controlled-release tablet with an extrudable core system. This reference described tablet cores consisting of 15 mg of polymer, 75 mg of sertraline hydrochloride, 190.5 mg of sorbitol, 2.1 mg of sodium lauryl sulfate, 15 mg of Klucel EXF, and 3 mg of magnesium stearate, coated with 7:3 cellulose acetate:polyethylene glycol at 6-8 wt.%, with a 900-micron diameter hole drilled through the coating.
Technical Deficiencies in Patent Claims
A primary reason for finding Claim 1 lacking inventive step was that the technical effects could not be ascertained based on the patent specification description. CNIPA determined that an extrudable core system with a semi-permeable membrane must contain a polymer such as a water-swellable polymer or viscosity-increasing polymer (thickening agent) to achieve the desired pharmacokinetic effects for once-daily tofacitinib administration.
The decision noted that while all relevant technical solutions described in the specification included a thickening agent, Claim 1 did not limit the presence of such an agent, covering both scenarios with and without a thickening agent. This discrepancy meant the actual technical problem solved by Claim 1 could not be grounded in the technical effects achieved by the specific solutions containing a thickening agent as described in the specification.
Implications for Pharmaceutical Patent Strategy
The collegiate panel concluded that a person skilled in the art would find it obvious to arrive at the technical solution of Claim 1, based on Evidence 6 combined with teachings from Evidence 10 (tofacitinib dosage strength), Evidence 4 (modified-release oral dosage forms), Evidence 7 (sustained-release formulations), and Evidence 9 (coating composition).
The patentee's failure to submit any response to the invalidation petition or participate in the oral hearing contributed to the unfavorable outcome. As the granted claims did not involve a thickening agent, it would no longer be possible to limit the claims by adding a thickening agent during invalidation proceedings, as such amendments would exceed the scope of granted claims.
This case demonstrates that pharmaceutical formulation patents face inherent challenges regarding inventiveness levels, and patentees should ensure necessary components are included at minimum in dependent claims rather than being deliberately omitted to obtain broader protection scope. The decision serves as a cautionary example for pharmaceutical companies developing patent strategies for drug delivery systems in China.