Merck Sharp & Dohme (UK) Limited v Halozyme, Inc

Consequential waiver of litigation privilege resulting from serving a Notice of Experiments in patent proceedings is confined by the experiment deployed and the issue or transaction it puts in question. It ordinarily extends to work-up experiments for that experiment and, where necessary to avoid unfairness, to material needed for completeness of the data. It does not automatically extend to every experiment or comparator polypeptide falling within the pleaded claims, to experiments directed to another patent, or to material said to support a separate insufficiency case. Outside clear inevitable-result and completeness-of-data cases, the approach is cautious and restrictive. A reagent problem does not by itself establish undue burden, and privately generated redacted material remains protected unless waiver is shown.

Merck Sharp & Dohme (UK) Limited v Halozyme, Inc concerned MSD’s application for further disclosure from Halozyme under an earlier case-management order requiring Mayne Pharma disclosure in connection with a Notice of Experiments concerning EP 347.

Halozyme had disclosed preliminary experiments and material using comparable protocols, but withheld documents concerning other comparator PH20 sequences and redacted parts of two experiments not relied upon. MSD argued that the material formed part of the work-up or a wider transaction encompassing infringement, validity and a new insufficiency plea. The central issue was whether service of the Notice had waived privilege in the further material and whether the redactions were justified.

Disposition

The court rejected MSD’s application for further disclosure. The remaining points were agreed and embodied in the order.

1. Applicable principles. The disclosure issue in patent experiments originated in Mayne Pharma Pty Ltd v Debiopharm SA [2006] EWHC 164 (Pat), [2006] FSR 37, particularly the risk of presenting a misleading picture by disclosing only a successful experiment. The court applied the more comprehensive principles in Magnesium Elektron v Neo Chemicals [2017] EWHC 2957 (Pat), [2018] FSR 11: the scope of waiver depends on what was deployed and why, and a cautious and restrictive approach is required outside clear inevitable-result and completeness-of-data cases.
2. Relevant issue or transaction. The court preferred Magnesium Elektron to the extent that Safestand Limited v Weston Homes Plc [2023] EWHC 1098 (Pat) might suggest a wider approach. Safestand was understood as recognising that waiver may extend more widely depending on the particular facts. Here, however, the relevant issue or transaction was confined by the Notice of Experiments to the experiment relied upon and its proper work-up.
3. Comparator material and insufficiency. The Notice relied on a comparator with SEQ ID NO: 3. Documents concerning the production or testing of different comparator sequences were not within the consequential waiver merely because the pleaded claims covered those sequences or the material might bear on insufficiency. The fact that insufficiency was pleaded did not itself make privileged material disclosable. A reagent problem or delay in validating an assay did not establish undue burden; MSD bore that burden and could conduct its own experiments.
4. Redactions and confidentiality. For two experiments not relied upon, Halozyme disclosed the parts using protocols comparable to the deployed experiment. The court found no basis for requiring disclosure of the redacted parts, which concerned different subject matter. There was no demonstrated cherry-picking, and experiments conducted in private remained confidential absent waiver or another basis for disclosure. Disclosure without confidentiality might itself cause further waiver.

This was a first-instance interlocutory decision. The judgment records earlier case-management proceedings before Richards J, who ordered disclosure in accordance with principles concerning work-up experiments. The present court rejected the subsequent application for further disclosure.