Julian Hitchcock of Field Fisher Waterhouse LLP contributed this guest blog entry:
The grant of a patent for induced pluripotent stem cells (iPSCs) in the United Kingdom in January and the notice issued by the US Patent and Trademark Office in February allowing claims under a US patent application entitled “Methods for Reprogramming Somatic Cells” signal a significant new feature of the stem cell patent landscape. But don’t imagine that stem cell patents are about to become straightforward.
Background
The origin of every cell in the adult body may be traced back to a cluster of cells sitting on the inside surface of a tiny cell ball that, within a week of fertilisation, fills the egg capsule. The potential of these pluripotent stem cells (PSCs) to give rise to any adult cell type means that they are extraordinarily valuable to the developed world. As the ratio of economically effective to economically ineffective citizens plummets with their aging populations, products derived from such cells hold out the hope, not only of a solution to chronic, degenerative disease, but to the prevention of socio-economic collapse. They do not, however, come cheap.
PSCs may be isolated from the cell balls using standard techniques, and subsequently grown in cultures for purposes of research or, very soon, treatment. The biological term for the cell ball is “blastocyst”, but it has acquired a moniker generally applied to a later-stage of development: “embryo”. The e-word has impeded stem cell research for many years. In the US, it lead to funding anomalies that persist despite the President’s efforts. In Europe, differences of practice between states about the permissibility of research using blastocyst-derived cells (misleadingly dubbed “embryo research” by the media) and patentability have presented a confused and incoherent picture to the world. In any event, embryos require eggs and therefore women donors, leading to a shortage of supply.
New routes to pluripotency
It has long been known that pluripotency can arise without fertilisation, for example in teratomas. Indeed, the success of cell nuclear replacement in cloning Dolly the sheep clearly indicates that factors in the cytoplasm of the receiving oocyte can induce pluripotency from the nuclei of highly differentiated adult cells.
In the light of the “ethical problems” associated with fertilisation-derived cells and the sparsity of supply, the idea of refining technologies to obtain pluripotent cells became an obvious target for research. One approach, the tinder to a veritable Parliamentary explosion in the UK, was to implant human nuclei into enucleated animal oocytes to create “cytoplasmic hybrid embryos”. But even as the relevant clauses of the Human Fertilisation & Embryology Bill were being debated by the House of Lords in November 2007, Shinya Yamanaka and James Thomson independently announced that they had induced pluripotent stem cells (iPSCs) from fibroblasts taken from human skin, using (respectively) retroviral and lentiviral transfection of genes which had been implicated in studies of “embryo” derived stem cells. The news that pluripotent stem cells had been created without recourse to “embryos” was immediately pounced on by opponents of “embryo” stem cell research, who declared that, now that there was an alternative source of pluripotent stem cells, there was no remaining excuse to conduct “embryo” research.
Commercial potential
iPSCs have a further significant advantage over their embryonic counterparts. Because they may be derived from a person’s own cells, there would be none of the rejection problems associated with the grafting of embryonic stem cells. This therapeutic benefit is, however, countered by a feature of the first wave of iPSCs, as one of the transfected genes used in their manufacture, C-Myc, is an oncogene: a gene which leads to carcinomas. Clearly, such cells are precluded from therapeutic use. The commercial value of such early iPSCs was therefore restricted to their use in drug testing. This is not to say that their worth might not be considerable. Nevertheless, human embryonic stem cells would continue to have the edge in commercial applications for the time being.
However, by the end of 2009, induction techniques had advanced so rapidly that it was possible to create iPSCs without the use of viral vectors or even genetic modification. It was shown that pluripotency might even be coaxed from a highly differentiated cell by direct delivery of certain proteins. Indeed, the genes that elicit pluripotency might be kicked into life by applying basic fibroblast growth factor in hypoxic conditions. These rapid advancements potentially place 2010 as a time of great commercial opportunity for iPSCs and the reprogramming technologies associated with their manufacture.
Patenting pluripotency
The first iPSC patent application was, unsurprisingly, filed in Japan, where Shinya Yamanaka had produced the first non-human iPSCs in 2006 and first human ones in 2007. In the wording of the corresponding European patent application, Yamanaka’s invention is
“a nuclear reprogramming factor for a somatic cell, which comprises a gene product of each of the following three kinds of genes: an Oct family gene, a Klf family gene, and a Myc family gene, as a means for inducing reprogramming of a differentiated cell to conveniently and highly reproducibly establish an induced pluripotent stem cell having pluripotency and growth ability similar to those of ES cells without using embryo or ES cell.”
Within a year of Yamanaka’s 2007 announcement, the Japanese Patent Office granted a national patent (No. 2008-131577) to Kyoto University. The pace reflected a sense of national panic, given that US efforts in the same field had been published on the same day as Yamanaka’s discovery. The concern was justifiable: some pretty serious iPSC work had been conducted around the time that Yamanaka produced his first human iPSCs. In 2008, for example, Nature referred to “unconfirmed reports” that Yamanaka had not produced human iPSCs until July 2007 and that Kazuhiro Sakurada had done so in April 2007. The significance of such possibilities becomes apparent when one considers that under Japanese patent law, like that of Europe, entitlement proceeds on the basis of “first to file”, whereas the rule in the US is “first to invent”. At the time of the Nature report, Sakurada was Chief Scientific Officer of iZumi Bio, a company based in California. The following July iZumi Bio merged with Pierian to form a new company, iPierian. Most recently, on 28 January 2010, iPierian announced that it had been granted a UK patent (GB2450603) for iPSC technology invented by Dr Sakurada; the first such patent to be granted outside Japan.
It is impossible to set out the full breadth of a patent in an article of this length. This is especially so before publication of the granted patent. However, the description given in the application as recorded on the EPO’s website is instructive:
“The present invention provides human pluripotent stem cells established from human postnatal tissue by the introduction of each of an Oct3/4, Sox2 and K1f4 gene and either the c-Myc gene or a histone deacetylase inhibitor, said human postnatal tissue comprising undifferentiated stem cells in which each gene of Tert, Nanog, Oct3/4 and Sox 2 has not undergone epigenetic inactivation.
In another aspect, the invention provides a method of producing human pluripotent stem cells from cells derived from human postnatal tissue, which comprises introducing thereinto either Oct3/4, Sox2 and K1f4, or Oct3/4, Sox2 and K1f4 as well as c-Myc or a histone deacetylase inhibitor. The invention further includes stem cells derived from this method.”
The word that leaps out here, is “or“. Without c-Myc, therapeutic applications are a possibility.
Exactly one week after the iPierian announcement, another America company, Fate Therapeutics, announced that it was to be granted the first iPSC patent in the US. The patent is based on inventions made by Rudolf Jaenisch, a founder of the Whitehead Institute. The significance of the Jaenisch patent is laid out unambiguously by Fate’s CEO, Paul Grayson:
“Dr. Jaenisch’s prescient vision in 2003 for creating human iPSCs and how reprogrammed cells could be used to revolutionize drug discovery and enable cell-based therapies is truly unparalleled.”
The year,- 2003-, is striking. Fate’s Press Release is emphatic:
“…In this 2003 application (20080280362), Dr. Jaenisch first describes the groundbreaking potential to generate human pluripotent cells from somatic cells without using embryos, oocytes and/or nuclear transfer technology and how reprogrammed somatic cells can enable autologous cell therapy, including the treatment, prevention or stabilization of neurological diseases such as Alzheimer’s, Parkinson’s or ALS. In addition, the application covers compositions used in screening for agents to generate these pluripotent cells and further describes specific agents that can be used to reprogram human somatic cells, including certain genes, classes of small molecules and pluripotency proteins. Fate Therapeutics also holds an exclusive license to other inventions of Dr. Jaenisch relating to iPSC technology including PCT/US2008/004516 with a priority date of April 7, 2007, which describes the reprogramming of human somatic cells using one or more pluripotency factors, including Oct3/4, Sox2 and/or Klf4, and combinations thereof.”
Strong stuff. What Fate is doing, of course, is reassuring investors of its freedom to operate. And there’s raw pride, too, with Jaenisch telling Bloomberg.com that although Yamanaka “was the first one to do it, we had the idea first”. But with the various different claims jostling so close to one another, the stem cell world is waking to the whiff of gunpowder. Bloomberg.com reported Jeanne Loring the director of the Centre for Regenerative Medicine at the Scripps Institute in California as “dreading the onslaught of new patents” as an impediment to medical research.
Return of the embryo?
Of all the advantages proclaimed for iPSCs in Europe, the avoidance of the “ethical problem” is the most trumpeted. That problem, of course, emerges from a single word: “embryo”. Ironically, the definition of that entity has now become so bloated as, in principle, to capture iPSCs. This arises in part from the decision of the Enlarged Board of Appeal of the European Patent Office in the WARF case (Case No. G 0002/06; 25 November 2008), that the term “embryo” should be construed in the light of the definitions used in national laws. In principle, this should mean the definitions which existed when the EU Biotechnology Directive (upon which the troublesome provisions of the European Patent Convention are based) came into force, notably that of the world’s first stem cell state: the UK. However, less than a fortnight before the WARF decision (13 November 2008), the UK passed legislation under the Human Fertilisation and Embryology Act 2008 (”HFE Act 2008″), which significantly widened the definition of the 1990 HFE Act. It did this in order to reflect technical advances and the decisions of the UK’s courts as to what the legislature would have had in mind by the term “embryo” had it known of those advances. High among those developments was the production of Dolly without fertilisation. While any sensible analysis of the facts required Dolly to have undergone embryonic development, the legal definition provided by the 1990 Act prescribed that an “embryo” was the product of fertilisation. (It is one of the curiosities of stem cell law that the Human Fertilisation and Embryology Act should have to be revised because of a sheep created without fertilisation or ever having been an “embryo”). In any event, the definition of embryo is now:
“a live human embryo”
and
“references to an embryo include an egg that is in the process of fertilisation or is undergoing any other process capable of resulting in an embryo”
The Molly effect
So let us postulate a near-future event, in which it is reported that a sheep, Molly, has been cloned from skin cells without the use of an egg. This is not incredible: in July 2009, Chinese researchers did exactly this in the case of mice. Indeed, one such iPSC mouse, Xiao Xiao (”Tiny”), successfully produced offspring by the more orthodox procedure. But Xiao Xiao himself began life rather differently. Lacking an egg, the researchers put iPSCs derived from mouse skin cells into a ball of blastocytes (undifferentiated cells that are ordinarily destined to become placental tissue), then popped the ball into Tiny’s mum.
Let us suppose that a group concerned with the ethics of human reproduction brings a case, on whatever grounds, to clarify the meaning of the term “embryo” under the amended HFE Act, just as the activist Josephine Quintavalle did some years ago in the wake of Dolly. The author submits that any such case brought in the UK would be bound by the decision of the House of Lords in the Quintavalle case, that it should look to the what Parliament would have meant by the new definition of “embryo”.
Such a tribunal would probably note from the new definition that, whereas fertilisation is no longer required, the new definition continues to make assumptions, notably that there is an egg. However, they would also note that the lawmakers had clearly hedged their bets: they knew that the pace of technology was such that eggs might not be necessary in the future. Indeed, Parliament defined the term after artificial gametogenesis had been demonstrated, a fact which clearly showed the growing ability to manipulate cells in the most fundamental of ways. This is why it used the words, “references to an embryo include…” and the distinctly self-referential description, “a live human embryo“. The likely upshot, therefore, is that the courts would hold the statutory definition to include a cluster of human iPSCs equivalent to the one that gave rise to Molly. The author submits that the courts would hold that this would have been the intention of Parliament at the time of the original 1990 Act.
Now, it would be possible to accuse the Enlarged Board of Appeal in the WARF case of being rather literal in its reading of national definitions (although little would have turned upon a more detailed reading in the light of case law). However, even if the EPO fails to take account of national definitions as understood by the relevant national law, the European Court of Justice is entirely at liberty to do so. In any event, the prospect exists of a “Molly effect”, under which iPSCs are excluded from patentability in some circumstances.
iTSCs
This doesn’t seem to make sense at first, because of a fundamental distinction between pluripotent and totipotent cells. Recall that, when fertilisation is involved, pluripotent cells are taken from the cluster of cells sitting on the inside surface of the resulting blastocyst; the inner cell mass. But of course, there is no obvious reason to wait until then. Why not take cells at an earlier stage, perhaps the four or eight cell stage, for example? The answer is that this would amount to human cloning, because the cells are “totipotent”: i.e. they can not only give rise to all the tissues of the human body, but also to trophectoderm. Trophectoderm is the extra-embryonic tissue that gives rise to the placenta. Pluripotent stem cells do not produce trophectoderm. And placental animals such as humans cannot develop to term without a placenta.
Now consider the effect of the European Biotechnology Directive (98/44 EC), whether considered on its own as a requirement of national laws in EU countries or as enshrined within the European Patent Convention.
In the first place, Article 6 of the Directive (from which Rule 28c of the EPC is derived) provides that “uses of human embryos for industrial or commercial purposes” are unpatentable. On the basis of the requirement, under the WARF decision, that account be taken of national understandings of the word “embryo”, it can be clearly seen that cells which are capable of producing somatic and trophoblastic tissue may be described as “embryos”. Such cells would be better described as “iTSCs”, or induced totipotent stem cells, than iPSCs. Now, the European Court of Justice (which is wholly independent of the European Patent Organisation) will in the near future rule on the same issues that had arisen in the WARF case (in the Brüstle reference from the German Federal Supreme Court), and it is in no way obliged to follow the EPO. But even if the ECJ or EPO were to hold the word “embryo” not to encompass iTSCs, Article 5 of the Directive (Rule 29(1)) would still provide that the human body, “at the various stages of its formation and development” cannot constitute a patentable invention.
Paradigm shift
The law can sometimes be illuminated by a ludicrous interpretation. Such is the case as regards the prohibition on patenting “processes for modifying the germ line genetic identity of human beings” (Article 6b / Rule 28b): the fact that a blot of induced totipotent cells never goes on to take out a mortgage and raise a family being as irrelevant as the purpose that happens to be stated in the relevant patent application. The exception is questionable on many grounds. Ethically, it stands opposed to the natural wish of parents to ensure that their children are unharmed by genes which they would otherwise inherit. Technically, it takes no account of the role of epigenetics: for example, it would prevent the patentability of factors which might be applied in utero to counter diseases arising from genomic imprinting. Indeed, epigenetics,- the control of genetic expression by factors outside the genome-, is ultimately what iPSC technology is all about. One can put it more strongly still, by saying that it is putting the cart before the horse to talk of cells before talking of those factors which determine their fate: cells are all phenotype, while their fate is determined by genomic control.
The law has yet to catch up with this important paradigm shift. What it implies is a change in the level of description of stem cells, from an essentially morphological account to one characterised by the epigenetic state of those cells. By way of illustration, embryonic stem cells and iPSCs may be distinguished by differences in cell surface antigens: a phenotypic characterisation. Yet the key distinction, as regards the difference between an iPSC and an iTSC (notional or otherwise), is not phenotypic, but epigenetic. Indeed, one can be quite precise, because in 2009 a group from the Babraham Institute in Cambridge identified the “gatekeeper” gene: Elf 5. Elf 5 is methylated (silenced) in embryonic stem cells but not in trophoblast. By inference, induced stem cells in which Elf5 is methylated should be incapable of producing trophoblast and thus truly equivalent to embryonically-derived pluripotent cells. Of course, the fact that Elf 5 is not methylated in a particular cell cannot be conclusive of totipotency: for example, Cdx2 deficiency has been shown to prevent implantation and there are likely to be downstream lineage gatekeepers which would also prevent full development. However, it illustrates vividly how the technology is beginning to focus upon genomic reprogramming: “stem cell” innovations may increasingly come from the small molecule end of things: medicinal chemistry.
Indeed, the biggest shift of all is already taking place. As the focus sharpens on the factors that determine cell fate, the necessity of pluripotent cells, embryonic or induced, may become an increasingly subsidiary issue.
In the world of stem cells, you have to run just to stay still.
The author, Julian Hitchcock, is a Senior Associate of Field Fisher Waterhouse LLP and Executive Director of the East of England Stem Cell Network.
Tags: Embryo, induced pluripotent stem cells, IP Landscape, IP Strategy, iPierian, IPS, iPSC, iTSCs, patent, Stem Cells
