Wednesday, August 02, 2006

On the obviousness challenge to WARF's '780 by PubPat

The obviousness challenge in the filed re-exam request on WARF's US 5,843,780 is based on three references, used separately or together: Robertson 1983, Robertson 1987, and Piedrahita 1990.

An interesting aspect is that the Piedrahita 1990 reference was used in an obviousness rejection by the USPTO, basically identical to that posed by PubPat, in an Office Action in the parent case on January 17, 1996 (the '780 patent is a cip derived from Ser. No. 08/376,327 filed Jan. 20, 1995.) The arguments used for obviousness over the Piedrahita 1990 reference are basically the same with the Robertson 1983 and Robertson 1987 references.

According to PubPat, WARF never overcame the rejection over the Piedrahita 1990 reference in the '327 prosecution and the matter did not come up in the prosecution of the later application (08/591,246). Piedrahita 1990 does not appear in the "references cited" section of the '780 patent.

An interesting question is whether or not these references create a substantial NEW question of patentability. Going beyond that procedural point, the substantive allegation raised is that any of the three references cited in the re-exam request present a basic "recipe" for isolating (human) embryonic stem cells:

(i) isolating a blastocyst
(ii) removing inner cell mass [ICM] from the blastocyst
(iii) placing the ICM on fibroplast cells
(iv) isolating stem cells once they become apparent
(v) maintaining the isolated ES cells on feeder layers

This basic recipe of the three references was for mouse embryonic stem cells, not for human embryonic stem cells. Thomson did isolate human embryonic stem cells, and the prior workers did not. Are Thomson's patent claims appropriate in scope to what he discovered?

In the area of SCNT, one notes that Hwang Woo-Suk really did clone Snuppy, a dog, but that Hwang Woo-Suk did NOT create patient-specific human embryonic stem cells. What works for animals, such as mice, does not necessarily work for humans. A pertinent question to be asked in the PubPat re-exam is: if the method were obvious in 1983, why didn't someone isolate human embryonic stem cells in 1983?

The Robertson 1987 reference (a book edited by Robertson) is mentioned in the text of the '780 patent, although in a different context than that used by PubPat:

The cell lines currently available that resembles primate ES cells most closely are human embryonic carcinoma (EC) cells, which are pluripotent, immortal cells derived from teratocarcinomas (Andrews, et al., Lab. Invest. 50(2): 147-162, 1984; Andrews, et al., in: Robertson E., ed. Teratocarcinomas and Embryonic Stem Cells: A Practical Approach. Oxford: IRL press, pp. 207-246, 1987).


Post a Comment

<< Home