‘A modified PH20 polypeptide, comprising one or more amino acid replacements in an unmodified PH20 polypeptide, wherein: the unmodified PH20 polypeptide consists of the sequence of amino acids set forth in SEQ ID NO: 3, 7 or 32-66; the modified PH20 polypeptide exhibits increased hyaluronidase activity that is at least 120% of the hyaluronidase activity compared to the unmodified PH20 polypeptide not containing the amino acid replacement(s); the amino acid replacement is at a position corresponding to a position selected from among [ a whole series of positions] with reference to amino acid positions set forth in SEQ ID NO:3.’
‘the modified PH20 polypeptide comprises up to 10 amino acid replacement(s) compared to the unmodified PH20 polypeptide not containing the replacement(s).’
‘(a) the production of any comparator PH20 polypeptide(s) the Defendant has produced or commissioned whether for potential use in experiments in these proceedings or as part of the Defendant’s preparation for experiments in these proceedings; (b) any attempt(s) by the Defendant to produce any comparator PH20 polypeptide(s) whether for potential use in experiments in these proceedings or as part of the Defendant’s preparation for experiments in these proceedings; (c) any testing in relation to any comparator PH20 polypeptide(s) the Defendant attempted to make, made, commissioned and/or purchased whether for potential use in experiments in these proceedings or as part of the Defendant’s preparation for experiments in these proceedings; (d) any testing conducted by the Defendant to validate the SEQ ID NO: 3 comparator PH20 polypeptide disclosed in the Product Report and Certificate of Analysis at Schedule A, Annex 2 of the Notice of Experiments;’ [i.e. any testing to validate the Creative Biomart enzyme] ‘(e) any testing conducted by the Defendant comparing Alt-B4 against SEQ ID No.3 for potential use as experiments in these proceedings (whether with or without exposure to a phenolic preservative and whether or not in preparation for experiments in these proceedings in respect of EP 622).’
“3. For the purpose of showing that BHA exhibits increased stability in the presence of a phenolic preservative(s) compared to the unmodified PH20 polypeptide not containing the amino acid replacement, Halozyme intends to compare BHA with a polypeptide with the sequence of SEQ ID NO: 35, which is the sequence from among the unmodified PH20 polypeptides listed in claim 1 of EP 622 that has the same C-terminal extent as BHA. 4. For the avoidance of doubt, the aforesaid does not mean that only data relating to a comparison of BHA to SEQ ID NO: 35 can be relevant to the issue of infringement. Halozyme’s case is that data relating to other comparisons may be probative of the presence of the Stability Feature. … 10. Paragraphs 2 to 4 above are repeated mutatis mutandis with respect to the Activity Feature.”
“We and our client have been working expeditiously to produce comparator PH20 polypeptides. However, it is now clear that it will not be possible for these polypeptides to be produced and analysed in the time available. As your client acknowledged in its Rejoinder dated27 November 2025 filed in the German PI Proceedings, the production of PH20 polypeptides can take many months”
‘Strictly without waiving privilege, Bionsystems have encountered an unexpected technical issue relating to a reagent sourced from a third-party commercial supplier, which has delayed the process of validating an assay which is intended to be used in our client’s experiments. As a consequence, as at the date of this letter, your client’s sample of BHA has not yet been tested.’ ‘One shipment of a potential alternative reagent is currently en route to Bionsystems and is scheduled to arrive there on Friday afternoon. A shipment of another potential alternative reagent from a different supplier is currently being arranged, which we hope will arrive in the course of next week, although that is not yet confirmed. If the alternative reagents arrive as expected and resolve the issue, or Bionsystems is otherwise able to solve the issue with the existing reagent, we anticipate that our client will require up to an additional 3 weeks to complete its experiments.’
‘Strictly without waiving privilege, we believe the experiments are now complete, but there some final points which require verification with Bionsystems, our client’s CRO.’
“Patent cases are no different to any other cases in that documents recording activity undertaken for the purpose of litigation attract privilege. Until they are deployed, they remain privileged. Once deployed, the question arises as to the extent to which, if at all, the effect of doing so is also to waive privilege in any other documents or material. The answer given in patent cases is in line with that in other cases although the patent case law has not always referred to all of the general authorities. In patent cases, as in any other, the opposite party and the court must have the opportunity of satisfying themselves that "what the party has chosen to release from privilege represents the whole of the material relevant to the issue in question". The problem arises in patent cases because, as in other cases, that proposition is itself somewhat imprecise: how are the boundaries of that which is relevant to the issue in question to be set?”
“…‘work up’ experiments should not be limited to preliminary investigations leading to the experiment relied upon but could encompass other related litigation experiments which provide materially relevant contextual information on the experiments relied upon.”
‘109. The combination of (i) the general law of privilege, (ii) the approach to scope of waiver generally and (iii) the approach taken in the patent case law relating to experiments suggests that the court should adopt a relatively cautious and restrictive approach to waiver of privilege in material relating to experiments in cases other than clear ones of the kind identified above. Neither the general law nor the specific patent case law provides a warrant for broad and general disclosure of all information about earlier experiments on which the experiments in question may have been based if a later experiment is deployed. To the contrary, waiver of privilege in material not deployed should only be treated as having taken place to a limited additional extent and only in so far as necessary to satisfy the specific objects of the law relating to waiver set out in Nea Karteria set out above.’
‘…in some cases citing the Nea Karteria passage, waiver of privilege in a document has been held to extend not just to the document as a whole but to other documents forming part of the transaction or communication in question.’
‘It is not possible to avoid these difficulties [as to the scope of waiver] altogether by reference to waiver of privilege taking place in the “transaction” as a whole, since that begs a related question of how the boundaries of the “transaction” are to be determined. There is, as Matthews & Malek acknowledges at para. 16.40, “room for argument in any given case as to what constitutes the “transaction” in question” and whether, even if that can be determined, the boundaries of implied or consequential waiver of privilege are limited to that.’
‘Halozyme has not explained how it came to represent to MSD (in Quinn Emanuel’s letter of9 January 2026 ) that the primary reason for requiring a 28-day extension for service of its Notice of Experiments was difficulties in producing “comparator PH20 polypeptides” which can take “many months”…’
‘27. On the basis of that representation by Halozyme, it is reasonable to infer that Halozyme intended to use one or more comparator polypeptides in its experiments (other than the one described in its Notice of Experiments), was struggling to make or have those made and ended up using the Creative Biomart product instead. Alternatively based on the representation Halozyme made to procure the extension of time, another explanation is that Halozyme did manage to obtain comparator PH20 polypeptides other than the Creative Biomart product, used those polypeptides in experiments but decided it preferred the results from experiments conducted with the Creative Biomart PH20 polypeptide 28. Given that Halozyme had previously pleaded that the comparator enzyme should be a PH20 having the amino acid sequence of SEQ ID NO: 35 of EP 347 and EP 622, the delay may have resulted from efforts to run the experiments with a PH20 having SEQ ID NO: 35 but that this ran into problems. But in any event Halozyme has not explained itself nor has it provided disclosure or made out a valid claim to privilege for that material. 29. According to the information provided by Halozyme, the material purchased from Creative Biomart is a formulation containing a PH20 enzyme having the amino acid sequence of SEQ ID NO: 3 of EP 347 (and EP 622). As noted at paragraph 10 above, Halozyme manufactures and sells a commercial product (Hylenex) that, according to its published description contains, along with a number of excipients, a PH20 enzyme having the sequence of amino acids of SEQ ID NO: 3. The Hylenex product is the comparator enzyme-containing formulation that Halozyme asserts it used for the experiments it relies upon in Germany and the Netherlands. No explanation has been offered by Halozyme as to why it didn’t simply use its own Hylenex PH20 enzyme in its UK experiments, as it did in Germany, rather than delay matters with repeated extension requests while it attempted to rely on other polypeptides.’
‘30. The importance of the identity of the comparator sequence and difficulties in making comparator polypeptides are matters in dispute on the pleadings in this case. It is relevant to pleaded issues of validity and infringement.’
‘Without waiving privilege, I can say that that is not the case. Halozyme has not conducted any experiments comparing the MSD ALT-B4 Sample Enzyme with any comparator enzyme other than the Creative Biomart product described in the Notice of Experiments.’
“31. Halozyme’s position is that service of the Notice of Experiments containing an experiment in which the activity of the MSD ALT-B4 Sample Enzyme is compared to that of the Creative Biomart product does not waive privilege in any documents relating to the production (or attempted production) or testing (as to which see above) of any other comparator PH20 polypeptide(s) (Bennett 8 paragraph 3(a)(i)-(iii)), for the reasons given by Mr Bennett or otherwise. That will be the subject of legal submissions.”
‘47. MSD is therefore seeking disclosure in relation to the production and testing of comparator polypeptides in circumstances where: (i) The Notice of Experiments uses a SEQ ID NO: 3 enzyme, which was obtained off-the-shelf from Creative Biomart. (ii) No other comparator polypeptide is relied upon by Halozyme. (iii) No other comparator polypeptide has been compared with the MSD ALT-B4 Sample Enzyme.’
‘that the experiments relied upon have nothing to do with any comparator with a sequence other than SEQ ID NO: 3, and no other comparator has been tested. Any work relating to preparation of an enzyme with a sequence other than SEQ ID NO: 3 cannot be regarded as work-up to the experiment in the Notice, nor is otherwise engaged by the principles in Mayne Pharma.’
‘As explained in paragraphs 28-30 above, the issue of difficulty in making comparator polypeptides and the consequences from validity and infringement of testing that makes a comparison to other comparator sequences is a pleaded issue in dispute between the parties. In relation to the difficulty in making the enzymes there is clearly a story to be told by the withheld disclosure, in circumstances where the basis for Halozyme obtaining its 35-day extension for service of its Notice of Experiments was explicitly due to difficulties producing comparator PH20 polypeptides (plural) in time for the purposes of its experiments. How those enzymes were produced and difficulties in producing them are part of the work up for the experiments relied upon. Any testing of activity of comparator enzymes other than the Creative Biomart PH20 relied upon in the Notice of Experiments is also part of the work up in the sense that the testing will have included testing of activity of the comparator enzymes. Producing only the results for the comparator that suits its case is a partial production of the material generated by that transaction: it’s liable to present only part of the suite of relevant results and is an exercise in cherry-picking by Halozyme. MSD’s position is that privilege has been waived in the whole transaction which includes the matters raised by MSD’s RFI and the disclosure now sought.’
‘31. This was, of course, on the basis that, if unmodified and modified polypeptides of different lengths are compared, there is no way of knowing to what extent any changes in activity or stability are due to the modifications or due to the different lengths. It is basic scientific protocol not to introduce more than one variable when trying to ascertain the effect of changing just one of them. This is, no doubt, the reason why Halozyme intended to use SEQ ID NO: 35, even though in the end they never did as described below.’
‘40. This response does not explain the basis for Halozyme’s redactions. Per its Disclosure Statement, Halozyme accepted that these documents constituted work-up – containing “results of experiments undertaken in contemplation of litigation which utilised comparable experimental protocol(s)” to those relied upon the Notice of Experiments – such that privilege has been waived. Indeed, documents 13 and 15 appear to themselves be comparable experimental protocols, yet Halozyme has selectively redacted certain parts of the protocol and results in respect of the same.’
‘(2) the results of experiments which utilised comparable experimental protocol(s) to the experiment relied upon in the Notice of Experiments, but whose results were not relied upon in the Notice of Experiments ("Category 2 Documents"). The Category 2 Documents consist of redacted protocols and results from experiments (referred to as Experiments A & B) that are different to the experiment which is the subject of the Notice of Experiments, and which were not experiments representing preliminary investigations leading to the experiment that was the subject of the Notice (in which case they would have fallen within Category 1). Once again, they are not documents or experiments that are the subject of the Notice of Experiments and Halozyme has not voluntarily waived privilege in them by its reliance on the Notice. Prior to service of the Notice both the redacted and unredacted parts of these documents were subject to litigation privilege. However, although Experiments A & B are different to the experiment which is described in the Notice, one part of the protocols for each of Experiments A and B uses the same assay and conditions as the experiment which is in the Notice, and conducting Experiment A or B therefore leads to the generation of some data which could be said to represent additional runs of the experiment in the Notice. Halozyme therefore accepted for the purpose of the UK proceedings (and subject toCPR 31.22 ) that the data in the Category 2 documents generated using the conditions used in the experiment of the Notice, and the parts of the Category 2 documents which set out how those data were generated, should be disclosed in accordance with the "completeness of data" principle in the Mayne Pharma line of cases. However, the redacted parts of the Category 2 documents relate to subject matter which could not possibly be characterised as a repeat run of the experiment in the Notice, and Halozyme therefore maintains that privilege in the redacted parts of these documents remains, and that they do not fall within the scope of the consequential disclosure obligations of Mayne Pharma. Halozyme therefore provided disclosure of the redacted documents to MSD, but resists disclosure of the unredacted versions.’
‘40. In paragraphs 36-37 of Bennett 8, Mr Bennett refers to the redactions made to the experimental protocol and results for Experiments A and B in the documents disclosed with Halozyme’s Notice of Experiments, and in paragraphs 39-40 he refers to Halozyme’s response to Requests 2 and 3 in the RFI, which relate to those redactions. 41. As I have explained above, Experiments A and B are not experiments relied on by Halozyme in its Notice of Experiments, nor are they experiments which led to the experiment in the Notice. The unredacted material disclosed in relation to Experiments A & B was disclosed under the "completeness of data" principles in the Mayne Pharma line of cases for the reasons explained in Halozyme’s disclosure statement. However, the redacted material (as Halozyme’s disclosure statement and RFI response make clear) does not relate to experiments which used comparable experimental protocols to the experiments relied on. Only parts of experiments A and B used protocols comparable to that of the experiment relied on in the Notice (and so those parts of the protocols and results were disclosed), whereas other parts did not (and so those protocols and results were not disclosed).’
‘Crosse 1 fails to provide a proper explanation as to the basis for the redactions made to documents 13-17 of Halozyme’s work-up disclosure (which we understand to be the “Category 2 Documents” referred to in Crosse 1). The only basis it is reasonable to infer is that the redacted material concerns testing conducted in the presence of a phenolic preservative. Whilst it is MSD’s position that privilege has been waived in these documents and that unredacted copies of the Category 2 Documents ought to have been disclosed, MSD is prepared to refrain from seeking unredacted copies of these documents if Halozyme confirms, by return, that the redactions to the Category 2 Documents do relate to testing conducted in the presence of a phenolic preservative.’
‘We note your confirmation that MSD will no longer seek an order for provision of the materials encompassed by paragraphs 1(d), 1(e) and 2 (insofar as it relates to Request 8 and 9 of the RFI) of the draft Order. With regard to the position set out in your first letter of 18 June that MSD will no longer seek an order for provision of unredacted copies of the Category 2 Documents (i.e. paragraph 3 of the draft Order) if our client were to confirm that the redactions to the Category 2 Documents relate to testing conducted in the presence of a phenolic preservative, we are taking instructions. However, our client would plainly be unable to provide your client with information characterising the nature of the experiments described in the redacted parts of the Category 2 Documents ("Category 2 Characterising Information") if the act of doing so might itself be said to amount to a broader waiver of privilege. Please therefore confirm the following by return: 1. That, if our client were to provide your client with any Category 2 Characterising Information, such information would only be disclosed to, and would be kept confidential by, the solicitors and counsel acting for MSD in the above-captioned proceedings, and the specific individuals at MSD responsible for instructing them in those proceedings; 2. That MSD will not argue, in these proceedings or otherwise, that the provision by Halozyme of any Category 2 Characterising Information amounts to a waiver of privilege in the information provided (with regard to any party other than MSD) or any other information whatsoever (with regard to any party including MSD); and 3. That any Category 2 Characterising Information provided by Halozyme will be subject toCPR 31.22 , and MSD will not make any application underCPR 31.22 (1) or oppose any application underCPR 31.22 (2) to maintain confidentiality and privilege in such information.’
‘The learned judge erred in principle in supporting his decision to award costs on the indemnity basis by the view he formed about [the] English experiments. The learned judge wrongly drew an inference from Halozyme’s maintenance of privilege.’