T 0395/00 (Stable hemoglobin compositions/BAXTER) 22-04-2004

Reasons for the Decision

Admissibility of late-filed documents into the proceedings (Article 114 EPC)

1. In accordance with Article 114(2) EPC the boards of appeal are empowered to disregard facts or evidence which are not submitted in due time. It is established case law that in appeal proceedings new facts and late-filed evidence should only very exceptionally be admitted if the material is prima facie so highly relevant so as to prejudice the maintenance of the patent in suit (see eg decision T 1002/92, EPO OJ 1995, 605, point 3.4 of the reasons.)

2. None of documents D21 to D23 has a bearing on the decision to be taken. This is especially true for document D23 which was used for a new objection of lack of novelty. The subject- matter disclosed therein differs in at least one feature from the claimed subject-matter: Oxygen is not removed from the container before the hemoglobin solution is added.

3. Therefore, none of documents D21 to D23 is allowed into the proceedings pursuant to Article 114(2) EPC.

Admissibility of the new argument under Article 123(2) EPC

4. The respondent submitted that decisions of the Enlarged Board of Appeal G 1/95 and G 7/95(EPO OJ 1996, 615; EPO OJ 1996, 626) should be construed such that patentee's consent must be obtained in relation to a totally new argument under Article 123(2)EPC even if part of the original opposition was made under Article 100(c) EPC.

5. A ground of opposition constitutes the legal basis for objecting to the maintenance of a patent.

6. Decisions G 1/95 and G 7/95 deal with cases where fresh grounds of opposition were introduced at the appeal stage. According to these decisions a ground is to be considered as "fresh" if it was neither raised nor substantiated in the notice of opposition nor was it introduced into the proceedings by the opposition division (see point 5.4 of the reasons of G 1/95). Hence, a fresh ground represents a new legal basis for an objection.

7. In the present case Article 123(2) EPC was raised as a ground of opposition and substantiated in the original notice of opposition of opponent 03 (now appellant II). The opposition division decided on this issue in its written decision. Therefore, following decisions G 1/95 and G 7/95, Article 123(2) EPC is not a fresh ground in these proceedings.

8. The board cannot identify in the two decisions cited, either generally or for the specific case of Article 123(2) EPC, a suggestion on how to proceed with new arguments in relation to already existing grounds of opposition. Therefore, the respondent's argumentation is not convincing.

9. A further question is whether there is another legal basis in the EPC for rejecting late arguments. Article 114(1) EPC applies in all proceedings before the EPO, though, due to their judicial and therefore less investigative nature, in a more restricted form in appeal proceedings. This requires that within the legal framework established by the parties, the boards consider all facts presented by the parties and decides which of them are crucial for the decision to be taken. In view of Article 114(1) EPC during the decision-making process "facts and evidence" on the one hand and "arguments" on the other hand are taken into account.

10. Article 114(2) EPC is a limitation on the obligation under Article 114(1) EPC in that it permits to exclude from the proceedings facts and evidence which are not submitted in due time. In contrast to Article 114(1) EPC, Article 114(2) EPC does not refer to "arguments".

11. The new attack under Article 123(2) EPC by appellant I does not constitute facts or evidence. In the case of amendments the "fact" is the amendment as such. "Evidence" for amendments is the submission of new pages comprising the amendment. Both events have taken place in due time. According to decision T 92/92 (dated 21 September 1993; point 2, paragraph 3 of the reasons) arguments may be understood "to include the parties' submissions as to the consequences that result from applying the law to the facts and evidence." Thus, the new attack represents a new argument.

12. Since Article 114(2) EPC is not a legal basis for disregarding late arguments, the argument is taken into consideration.

Amendments (Article 123(2) EPC)

13. According to Article 123(2) EPC a European patent application may not be amended in such a way that it contains subject-matter which extends beyond the content of the application as filed. This requires examination as to whether an amendment results in the introduction of information which the skilled person cannot derive directly and unambiguously, either explicitly or implicitly, from the originally presented application documents.

14. Appellant II contends that the original application documents do not contemplate using deoxygenated hemoglobin in the context of making the hemoglobin solution, but only in the context of its storage. Therefore, he considers the expression in claim 1 "adding a purified substantially deoxygenated hemoglobin solution to the container" not to be supported by the original application documents.

15. Claim 4 of the application documents as originally filed relates to "a method to prepare a hemoglobin based composition comprising:

a) adding a purified hemoglobin solution to an oxygen impermeable container, and

b) storing said container at a temperature of about 5°C to about 45°C for a sufficient time to permit autoreduction of sufficient methemoglobin for the composition to function as an oxygen carrying solution upon administration to a patient."

16. Example 4 of the application as filed discloses undeoxygenated hemoglobin solution as a starting material. All the other seven examples use a deoxygenated solution. Thus, the reader of the application underlying the patent in suit understands that both possibilities are referred to. The restriction of the subject-matter of claim 1 to one of these directly derivable possibilities does not contravene Article 123(2) EPC.

17. The second issue under Article 123(2) EPC is whether a reader of the claims 1 and 2 of the patent in suit would interpret the expression "removal of oxygen from an oxygen impermeable container" broadly as encompassing the removal of a non-specific amount of oxygen and thus including the possibility of removing only a small amount. This would however according to appellant II not be supported by the application documents as originally filed.

18. The application stresses in several passages the importance of removing oxygen completely, for example in Examples 2 and 6 (corresponding to Examples 2 and 5 of the patent in suit).

19. Since a claim is not read in isolation, but always in the context of the complete application, the skilled reader would not construe the above cited expression such that it related also to the partial removal of oxygen, but rather that the complete removal by any suitable means - for example flushing with nitrogen - was necessary for successfully carrying out the method.

20. The board is convinced that the amended passage would be interpreted by the skilled reader in this sense in view of the application documents as a whole and as originally filed and thus it cannot be regarded as added matter.

21. The requirements of Article 123(2) EPC are fulfilled.

Sufficiency (Article 83 EPC)

22. In the assessment as to whether a European patent application fulfils the requirement of Article 83 EPC, it is an established principle in the case law of the boards of appeal that, for the disclosure of an invention to be sufficiently clear and complete, the skilled person, on the basis of the information provided in the application itself and by using the common general knowledge at the application date (or priority date, as the case may be), has to be able to achieve the desired result without undue burden and without exercising inventive skill (see eg decisions T 694/92, OJ EPO 1997, 408 and T 612/92, dated 28 February 1996).

23. An objection of lack of disclosure can only be successful if the party alleging lack of sufficient disclosure substantiates its doubts by tangible evidence. Such evidence could for example come in the form of experiments demonstrating that the exact repetitions of the conditions of an example of a patent falling under the scope of the claim do not lead to the desired result.

24. It was argued that Examples 1 and 4 of the patent in suit as well as document D11 disclose a method which is identical to the claimed one, but that the methemglobin content of the hemoglobin solution did nevertheless not fall to less than 15%.

25. It is true that at first sight the method of Example 1 of the patent in suit seems to have all the features of the claimed method. However, this impression is shifted once this example is considered in the context of Example 2. In Example 1 the inventors express discontent with the experimental conditions: "Despite the efforts to exclude oxygen, the sample initially contained 20% oxy diaspirin ....". Example 2 begins with a statement reflecting the wish to change the experimental set-up: "In this experiment efforts were taken to ensure that the samples were stored in sufficiently oxygen impermeable containers to observe autoreduction". It can be inferred from these statements that the inventors consider that the method of Example 1 was not carried out adequately because oxygen was not sufficiently excluded. Consequently, the combination of Example 1 and 2 conveys that Example 1 does not reflect the claimed method.

26. Similar conclusions can be drawn for Example 4 which has to be considered in combination with Example 5. Example 5 discloses that the same technology as in Example 4 was used, but that rigorous efforts were taken to remove oxygen from the isolator, the container and the hemoglobin solution. Thus, the method as carried out as in Example 4 is not within the scope of the claimed method.

27. In this context it is also noted that the board cannot follow appellant II arguing that the skilled person was left without guidance as to the manner and extent of efforts to be taken in order to modify Example 1 and 4 such that a methemoglobin content of less than 15% was achieved. Example 2 specifies that the efforts concentrated on the containers (see above). Example 5 explains that "rigorous efforts were employed to purge oxygen from the isolator, the packing containers and the hemoglobin solution. After fogging, the isolator was purged with low-oxygen grade nitrogen. The purge line was then switched to ultra-pure nitrogen with an in-line oxygen trap and the isolator was purged further. All components were carefully purged with the same ultra-pure nitrogen." Thus, the skilled person is given information about what to do in case of failure.

28. Document D11 deals with the stability of a stroma-free hemoglobin solution during extended storage. Some experiments involve storage under vacuum or under nitrogen: An aliquot of hemoglobin solution is placed in a glass ampoule and evacuated and then refilled with oxygen-free nitrogen. The complete procedure is repeated three times. Then the ampoule is sealed after a final evacuation or after refilling with nitrogen. Although this disclosure is prima facie very similar to the claimed procedure, it differs however in at least one essential aspect, namely in that oxygen is not removed from the ampoule prior to adding the hemoglobin solution. Consequently, the method of document D11 is not the same as the claimed method and therefore lacks evidential weight.

29. Thus, neither Examples 1 and 4 nor document D11 are appropriate to call in question the sufficiency of disclosure of the patent in suit.

30. Moreover, it was submitted that some terms of claim 1 were so broad that is was implausible that the method could be carried out successfully over the whole breadth of the claim. The main evidence brought forward in support of this argument relates to the fact that on the one hand 5°C was the lowest temperature value in the claimed method whereas on the other hand Tables 5 and 6 of the patent in suit showed that at 5°C autoreduction did not take place.

31. However, the iron atom in the middle of the four heme prosthetic groups of the hemoglobin molecule is the site of oxygen binding and release. In order to maintain this reversible oxygen binding capability, the heme iron must be in the Fe2+ state. When a solution of hemoglobin is stored for longer periods, the iron tends to oxidize to the Fe3+ state, giving the methemoglobin form which does not reversibly bind oxygen and is therefore physiologically ineffective.

32. The claimed method relies on the discovery that under a certain set of conditions an autoreduction reaction occurs that spontaneously converts the methemoglobin in the solution to the physiological Fe2+ hemoglobin. After the autoreduction of methaemoglobin has occured the solution can be stored for a long time even at room temperature.

33. Table 5 shows data about the methemoglobin content in a hemoglobin solution. At 25°C the methemoglobin level increases on day 1 and than decreases until the end of surveying on day 56. At 5°C this trend is not visible, but a small increase and decrease of the methemoglobin content alternate with each other. Table 6 shows a similar phenomenon with the additional complication that at day 59 the measuring apparatus was changed and overall higher values are obtained. But, indeed both tables seem to demonstrate at first sight, that the methemoglobin content in the solution has not decreased to less than 15% after the same number of days at 5°C compared to 25°C. This is however no proof that autoreduction does not occur and that therefore the claimed method does not work at 5°C because, if this was the case, a steady increase of methemoglobin would be observed. In the board's view the data may indicate that at 5°C autoreduction takes longer to start. Indeed, the patent specification discloses at the top of page 4 that the autoreduction reaction is accelerated at higher temperatures and on page 5 at the bottom that during storage at 5°C autoreduction is very slow.

34. Thus it is concluded that the objections of the appellants as to the insufficiency of disclosure were not substantiated by convincing evidence. Consequently, the requirements of Article 83 EPC are fulfilled.

Novelty (Article 54 EPC)

35. It was submitted that the subject-matter of claims 1 to 5 and 7 lacks novelty in view of Example 6 of documents D1/D5. The documents relate to a method for preparing purified hemoglobin solutions. For this purpose the deoxygenated hemoglobin solution is heated typically at a temperature 60°C for 10 hours. This procedure selectively inactivates viruses and removes non-hemoglobin proteins while the hemoglobin remains stable and retains its biological activity.

36. The method of documents D1/D5 differs from that of the patent in at least the characteristic that the container is not - as required by claims 1, 2, 4, 7 - made oxygen-free before the hemoglobin solution is added. Consequently, for this reason alone document D1 or D5 does not anticipate the subject-matter of the claims.

37. Moreover, appellant I considers document D18 as novelty- destroying for the subject-matter of claims 1 to 4. Document D18, an abstract from 1942 reads as follows: "Human haemoglobin solutions made isotonic with blood plasma are sterilized by Seitz filtration. The solutions are completely reduced by vacuum extraction with a Hyvac pump. They are then sealed in vacuo in glass ampoules. Although exposed to light and warm room temperatures these solutions show no methaemoglobin formation for periods up to three months." A comparison of this disclosure with the claimed method reveals that, like in document D1 or D5, there is no removal of oxygen from the glass ampoules before the haemoglobin solution is added. Therefore, document D18 cannot be novelty-destroying for the subject-matter of the claims.

38. Consequently, novelty of the subject-matter of the claims is acknowledged. The requirement of Article 54 EPC is fulfilled.

Inventive step (Article 56 EPC)

39. In vivo the heme iron is continuously oxidized leading to methemoglobin formation. The red blood cells contain, however, a number of enzyme systems that either reduce the methemoglobin or eliminate activated oxygen products such as superoxide that can also oxidize heme iron. Therefore, less pure preparations of hemoglobin that still contain a considerable amount of these enzymes are more resistant against oxidation during storage. However, since contaminating proteins may cause toxic or immunogenic reactions in patients, it is desirable to use hemoglobin solutions for administration to patients that are almost free of these contaminating proteins. Due to the lack of the protective enzymes however, the heme iron in these solutions is more easily oxidized leading quickly to an undesirably high methemoglobin content. Thus, these purified preparations quickly loose their biological activity during storage.

40. Oxidation in pure and less pure hemoglobin solutions is even more accelerated at room temperature. Therefore such solutions are usually stored refrigerated or frozen. This is however inconvenient because these solutions cannot be immediately administered to patients - which in medical emergency situations can be a life-saving measure. Moreover, storage at room temperature has the further advantage to prevent mistakes by inappropriate thawing or damage to the solution by inadvertent unrefrigeration. Finally, hemoglobin preparations which are stable at room temperature are easier to handle during transportation.

41. The patent in suit deals with the specific problem of preserving highly purified hemoglobin solutions at room temperature.

42. In accordance with the case law the closest prior art for objectively assessing inventive step is generally that which aims at the same purpose and having the most relevant technical features in common.

43. In view of this case law document D3, suggested by appellant II as the closest prior art, is not suited because it does not deal with the same purpose as the patent in suit, i.e. the storage of purified hemoglobin solutions (see section 48. below).

44. Document D1, suggested by appellant II as the closest prior document, does not explicitly address the problem of storage of purified hemoglobin solutions, but deals with their preparation. The purification-method of document D1 is mentioned in the patent in suit as one possibility of obtaining the starting material of the claimed method (see page 4, lines 33 to 34). The document mentions on page 7 that hemoglobin solutions are usually stored cold or frozen to avoid oxidation. In the board's view a person skilled in the art would infer from this general statement that this applies to the solutions prepared in document D1 as well. Thus, although not dealing with storage, the board considers document D1 as the most suitable starting point because once one has prepared a highly purified hemoglobin solution it is evident that it must be stored.

45. In view of document D1 the problem underlying the patent in suit is to provide means for making and storing a purified hemoglobin composition with less than 15% methemoglobin which is stable against oxidation during storage at convenient temperatures.

The solution to this problem is a set of conditions which are described in claims 1, 2, 4, 7.

Examples 2, 3, 5, 6 demonstrate that the claimed method solves the above formulated problem.

46. The question to be answered for the evaluation of inventive step is whether there is prior art which alone or in combination renders this solution obvious.

47. It has been argued that it was evident in view of the hemoglobin stability during heating at 60°C disclosed in document D1 that hemoglobin could be stored at ambient temperature. In the board's view this conclusion cannot be drawn. Firstly, the solution heated in document D1 is not purified in the sense of the patent. On the contrary, it is the purpose of the method to prepare such a solution. Secondly, the heating process requires stability only for a shorter period. Thus, document D1 alone does not give a hint to apply the claimed method as a solution to the above formulated problem.

48. The appellants were furthermore of the opinion that document D3, document D9, document D11, document D18 and document D19 contained pointers to the solution provided by the patent in suit.

49. However, as far as documents D3, D11 or D18 are concerned, none of them refers to highly purified hemoglobin solutions. Document D3 discloses the preparation of derivatives of hemoglobin for scientific use and sets out in its first paragraph that "preparation of the different derivatives can often be done directly from the hemolysate without any further purification. This is justified by the fact that hemoglobin is the major proteic component of the erythrocytic cytoplasm". The assays of document D11 are carried out with hemoglobin purified by filtration through a 0.22µm filter or by crystallisation. Both methods mainly remove membrane components. Although a small percentage of the protective enzymes is membrane-bound, the greater amount is soluble and remains in the filtrate giving rise to a less purified hemoglobin solution. Document D18 uses a Seitz-filtrated hemoglobin preparation. As well as the methods of document D11, this method only removes particulate matter with the respective consequences on purity of the solution. Since none of these documents relates to highly purified hemoglobin solutions, a person skilled in the art being aware of the specific problems involved with them, would not have expected to get any helpful advice from these documents for solving this specific problem. Therefore, he would not have combined any of them with the closest prior art document in order to solve the problem underlying the patent in suit.

50. In decision T 745/92 (dated 8 June 1994) the board sets out that "when assessing inventive step, the disclosures of two prior documents (...) may only be combined so as to result in a finding of lack of inventive step in a claimed invention if, on an objective assessment, it would have been obvious for a skilled person, when seeking to solve the problem underlying the claimed invention but without knowledge of the claimed solution to that problem, so to combine them." Analogously, the board finds in the present case that a person skilled in the art starting from document D1 and seeking a method to make and stably store a purified hemoglobin composition with less than 15% methemoglobin at convenient temperatures would not have taken any of these documents into consideration at all and that therefore, they do not render the claimed invention obvious.

51. Document D9 is a general textbook about hemoglobin and myoglobin in their reaction with ligands. It describes methods for preparing hemoglobin with different degrees of purity. In the short chapter about storage no distinction is made between the purified or less purified hemoglobin. It is generally suggested that the best way of storage for several weeks is in the form of oxyhemoglobin in the cold or as deoxyhemogloboin in vacuo or under an inert gas in the cold. The document is not only silent about specific process steps or the methemoglobin content, but also it does not give an indication that deoxyhemoglobin could be stored at ambient temperatures.

52. Document D19 is a study about the equilibrium of oxyhemoglobin and deoxyhemoglobin in closed cuvettes and does not touch on the subject of storage. If a person skilled in the art had taken this document into account at all, all that it could take from it would be that, when oxyhemoglobin is transferred anaerobically into cuvettes that were flushed with nitrogen before and which are tightly stoppered after transfer, the oxyhemoglobin is transformed to deoxyhemoglobin. Thus, not only is oxyhemoglobin used as a starting material, but also there are no indications about the methemoglobin level during this manipulation.

53. During the deoxygenation reaction of oxyhemoglobin free oxygen is created. Document D19 suggests that oxygen may be consumed by the system by "reversibly autooxidating hemoglobin". The authors speculate that SH-groups could be involved in this reaction. It has been argued that this amounted to the description of the autoreduction reaction which is the underlying chemical mechanism of the present invention. In the board's view this disclosure in document D19 is ambiguous because it could not only relate to the oxidation of the heme iron, but also to oxidation of the SH-groups to an S-S group. Consequently, document D19 is not considered to disclose autoreduction in the sense of the patent in suit.

54. Hence, none of the documents renders the subject-matter of claim 1 obvious. Independent claims 2, 4, and 7 all refer to the features considered inventive in claim 1 and thus the respective reasons apply. Consequently, the subject-matter of all claims involves an inventive step.