Although both patents pertain to fusing a therapeutic protein to albumin, one obvious difference between the patents is that HGSI’s patent refers to therapeutic proteins in general while GTC’s refers to EPO, specifically.
However, the most important distinction between the patents (IMO) is that HGSI’s patent includes claims for variants of a therapeutic protein in which glycosylation sites may be changed, while GTC’s patent is restricted to embodiments where one or more EPO glycosylation sites have been changed. GTC’s patent also includes claims for making such a fusion protein transgenically.
It is therefore my opinion that GTC’s patent is designed to support an EPO-albumin fusion protein that GTC has already produced in transgenic goats. The reason for the restriction in GTC’s patent to EPO variants where one or more glycosylation sites have been changed is presumably that the fusion protein produced by GTC’s goats happens to come out with altered glycosylation.
Differences in glycosylation between an endogenous protein and a recombinant therapeutic protein are not a new idea, of course. What’s pertinent is that the EPO glycosylation produced by GTC’s goats may offer some therapeutic advantage relative to endogenous EPO in efficacy or safety. GTC is probably unwilling to talk about this with any specificity because the company has not even disclosed that there is a preclinical EPO program underway.
What we do know is that GTC has made claims similar to the above (e.g. improved ADCC) with respect to minor variations of other therapeutic proteins that are produced transgenically. (A considerable portion of the recent annual shareholders’ meeting was devoted to this topic.)
Getting back to your question about the two patents, I surmise that GTC has attempted to “fence in” the IP in HGSI’s patent by adding the requirement of one or more changes in glycosylation as well as the option of producing the fusion protein transgenically. If a commercial product based on GTC’s patent should ever come to market, the overlapping claims in the two patents might end up in litigation. GTC would then presumably argue that HGSI’s patent is overly broad and some of the claims ought to be thrown out. Regards, Dew
p.s. I am not a patent attorney so please consider the above with all due skepticism.
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