Regen Lab v Estar Medical - Equivalents and Numerical Limits

A recent judgment of the Patents Court, Regen Lab v Estar [2019] EWHC 63, adds to the growing list of cases where judges have had to develop the approach to the doctrine of equivalents under English law. HHJ Hacon ultimately found the patent in question invalid, but of more interest to many are the obiter conclusions he reached on the question of equivalence. The Claimant in this case had taken the position that their main infringement argument was on the basis of equivalence and not normal construction.

The judgment was delivered towards the end of January 2019 following a trial in late June 2018. It was delayed by an (unsuccessful) application brought by the Defendant after the trial had concluded to introduce new evidence and re-open the trial, which resulted in a further hearing in January.

Background

The Claimant, Regen, is the owner of a patent directed towards preparing blood plasma which had been enriched in platelets and other factors (known as PRP). PRP is used in clinical settings to promote wound healing, and is also used in diagnostics, to assist in diagnosing conditions associated with the blood.

The method claimed in the patent employed a thixotropic gel and a centrifuge to prepare PRP. These gels have the unusual property that when they are centrifuged they change phase from a solid to a liquid. When the centrifuging ends, the gels solidify again. During the centrifuging, the gel will migrate within the centrifuge tube to a position appropriate to its density. If there are components in the centrifuge tube of both a greater and a lesser density than the gel, at the end of the cycle the gel will form a solid layer between the two. The different components of blood have different densities (red blood cells being the densest, platelets and white blood cells of middling density and plasma the least dense). In the patented method, the thixotropic gel formed a layer between the red blood cells and the remaining components of the blood, which made harvesting PRP easier.

Infringement proceedings were brought by Regen against the Estar on the basis that they were supplying kits in the UK which are subsequently used to make PRP according to the patented invention. Estar counterclaimed for revocation.

The Law on Equivalents

While the patent was held invalid, HHJ Hacon went on to consider how the UK’s new doctrine of equivalents applied to the claims with numerical limits.

Significance of the Inventive Concept

Claim 1 of the patent was as follows:

“A process for the preparation of a cell composition, comprising the steps of:

(a) Centrifuging whole blood in a separator tube selected from:

- a glass separator tube containing a polyester-based thixotropic gel and a buffered sodium citrate solution at 0.10M;

and

- a polyethylene terephthalate separator tube containing a highly thixotropic gel formed by a polymer mixture and an anhydrous sodium citrate at 3.5mg/mL;

(b) Separating enriched platelet rich plasma from full plasma by removing about half of the supernatant containing platelet poor plasma;

(c) Re-suspending the enriched plasma;

wherein the centrifugation step a) is performed at a force of about 1500g up to about 2000g in a sufficient length of time to form a barrier between plasma containing platelets, lymphocytes and monocytes and a pellet containing erythrocytes; the separation step b) is made by collecting the supernatant from atop of said barrier and wherein the enriched plasma is enriched in leucocytes, thrombocytes and adhesion proteins as compared to native whole blood.”

The Defendant’s process had two variations from claim 1: the gel used was not polyester-based, and the buffered sodium citrate had a molarity of 0.136M (relevant features underlined above).

The inventive concept was identified as the preparation of PRP for solely therapeutic use by employing a thixotropic gel wherein (a) there is only one centrifugation and (b) after centrifugation about half the supernatant is removed and the platelets are then resuspended in the enriched plasma. Estar’s own expert had suggested in evidence that neither of the two differences in the Estar’s process mattered much in relation to the operation of the process - and that the key was the density of the gel rather than its chemical composition. However, he had gone on to suggest that because different gels have different properties, the skilled person would assume that the gel was named for a reason (even if no reason was given).

It is becoming increasingly clear that the precise identification of the inventive concept will have a significant impact on the answers to the Actavis questions, and is likely to be a highly contested element of the equivalents infringement analysis. The inclusion (or not) of features such as the chemical composition of elements may have a determinative effect on the answers to the Actavis questions.

Having agreed that Estar’s process fell outside the claims on a normal interpretation, HHJ Hacon moved on to consider the three Actavis questions applied to equivalents:

1. Notwithstanding that it is not within the literal meaning of the relevant claim(s) of the patent, does the variant achieve substantially the same result in substantially the same way as the invention, ie the inventive concept revealed by the patent?

2. Would it be obvious to the person skilled in the art, reading the patent at the priority date, but knowing that the variant achieves substantially the same result as the invention, that it does so in substantially the same way as the invention?

3. Would such a reader of the patent have concluded that the patentee nonetheless intended that strict compliance with the literal meaning of the relevant claim(s) of the patent was an essential requirement of the invention.

Some specific issues of law arose on the question of equivalence which are of wider relevance.

Application to Variants with Multiple Differences

In some cases an allegedly infringing product or process will have multiple elements which are different from the claim features on a purposive construction. In this scenario, the question which arose was whether the elements should be assessed as equivalents separately or if the differences should be considered in combination.

HHJ Hacon concluded that the relevant question is whether or not the variant falls within the claim, taking equivalents into account, as a whole. Element by element analysis may be a convenient way to proceed at times, but there must be one overall conclusion in relation to the variant.

Having found that the precise gel and buffer compositions were not part of the inventive concept, HHJ Hacon concluded that changing them made no difference to the exploitation of the invention. The answer to question 1 was “yes”, the process achieved substantially the same result in substantially the same way. The answer to question 2 was also “yes”.

Application to Numerical Claims

Estar tried to argue that the doctrine of equivalents could not apply in relation to a numerical feature of a claim. Specifically, they submitted that when it came to numerical limitations a skilled person who concluded the product or process fell outside of the claim on a normal interpretation was then bound to conclude under the third revised Improver question that the patentee intended strict compliance. The judge disagreed. To follow this line of thinking, he explained, would require numerical claims to be treated as a "special class" of claims which did not require consideration of the doctrine of equivalents. In addition, if (as discussed above) the scope of purposive interpretation has been reduced by the doctrine of equivalents then this could unintentionally lead to numerical claims having a narrower interpretation than pre-Actavis. Numerical claims must, he therefore concluded, be treated the same as other claims and the doctrine of equivalents applied accordingly.

In this case, the arguments on numerical limits concerned the molarity of the sodium citrate and Actavis question 3. The Defendants had argued that the skilled person would understand strict compliance with the 0.10M limit to be required. Having decided that numerical limits were not outside the doctrine of equivalents, HHJ Hacon concluded that the use of the extra decimal point (0.10 rather than 0.1) was relevant to normal construction but not to equivalents.

Ultimately, the judge concluded that the molarity of the sodium citrate was not essential to the inventive concept and would not have been so regarded at the priority date. Accordingly, question 3 would only have been answered “yes” if there was a sufficiently clear reason in the patent or the general knowledge of the skilled person to indicate strict compliance. There being no such indication, the answer to question 3 was “no”.

Accordingly, HHJ concluded that the patent would have been infringed by equivalents (and also rejected a possible file wrapper estoppel argument).

Conclusion

Regen joins the dozen or so cases heard since Actavis v Lilly which have considered the UK’s ‘new’ doctrine of equivalents. At least as far as Regen is concerned, the suggestion is that the courts will take a pragmatic approach to equivalents and won’t hesitate to find infringement despite clear chemical or numerical limitations in the claim not being satisfied. This continues a trend of first instance decisions finding infringement in the face of clear non-infringement on the basis of normal interpretation, and of prosecution estoppel arguments being very difficult to succeed on. It remains to be seen if this approach will be approved by the higher courts in due course.

It is also noteworthy that in nearly all cases finding infringement based on equivalence there has been an accompanying finding of invalidity (where it was in suit). However, none of these cases have focused directly on a "squeeze" between the broader scope of equivalence resulting in invalidity. In this case, for example, the inventive concept was more "restricted" than the integers encompassed by the claim, which begs the questions of what happens when it is the other integers in the claim that render the entire claim novel. How the UK courts will deal with such matters remains of considerable interest.