Sandoz AG & Ors v Biogen MA Inc

A patent claim must be construed by reference to its actual language and purpose. Technical features disclosed in the specification cannot be read into a claim when the patentee deliberately omitted them. Conversely, a numerical threshold expressly included in the claim cannot be ignored or treated as an arbitrary label.

A claim covering a class of assays is insufficient where the disclosure does not enable the skilled team to identify the claimed clinical threshold across that class, or to know whether its assay produces the required result. A method of stratifying PML risk by antibody titre was also insufficiently broad because it did not work for patients previously treated with immunosuppressants. An off-shore assay was not used in the United Kingdom merely because its results were used there.

Sandoz sought revocation of Biogen’s patent, EP (UK) 3 575 792, concerning an ELISA-based method for assessing the risk of progressive multifocal leukoencephalopathy by reference to anti-JCV antibody levels. Biogen counterclaimed for infringement in connection with Sandoz’s proposed biosimilar natalizumab product and assay.

The principal issues were construction of the claim, insufficiency, excluded subject matter, added matter, inventive step, territorial infringement, infringement by equivalents and proposed Arrow-style declaratory relief concerning a pending divisional application.

1. Construction. Claim 1 covered a class of assays containing the expressly stated assay features. Details of the Gen2 assay that were not included in the claim could not be read into it. The index value of 1.5 was a deliberate limitation and could not be ignored. The claim did not, however, specify what the index value was relative to. The construction advanced by Sandoz was therefore adopted: [2017] EWHC 3482 (Pat) was applied. The expression “>1.5” was a bookend and meant greater than 1.5.
2. Insufficiency. On the adopted construction, the patent did not enable the skilled team to produce an assay giving the same clinically relevant threshold as the Gen2 assay without undue burden, or to determine whether it had done so. The missing cut-off calibrator, HPVLP preparation and other assay parameters were material. Claim 1 was also insufficient for breadth because antibody titre did not discriminate PML risk in patients previously treated with immunosuppressants.
3. Other validity objections. The excluded-subject-matter objection failed because the claimed contribution was technical. Claim 8 added matter over the parent PCT application because the claimed combination of an index value above 1.5, extended natalizumab treatment and absence of specified immunosuppressants was not disclosed. The patent was not obvious on the narrower constructions. On the broader constructions, however, the claim would lack a technical contribution over WO369.
4. Infringement. The claimed assay method was performed outside the United Kingdom. Reporting and using the result in the United Kingdom did not amount to use of the claimed method there. If valid, the Sandoz assay would nevertheless infringe by equivalents on the adopted construction.
5. Declaratory relief. The proposed declaration concerning the PCT and pending divisionals was refused. It would effectively determine that no valid patent could arise from the PCT and would usurp the function of the EPO.

The patent was therefore invalid; the infringement counterclaim failed; and the declaration was refused.