Precision BioSciences Issues Update Regarding Recent U.S. Patent Office Action Concerning Cellectis` Patents

RESEARCH TRIANGLE PARK, N.C.--(Business Wire)--
The United States Patent and Trademark Office (PTO) is reexamining two currently
issued U.S. patents owned by the Institut Pasteur and the Universite Pierre et
Marie Curie, and licensed to Cellectis SA (Alternext: ALCLS). The two patents
belong to a family of thirteen issued U.S. patents, which includes U.S. Patent
Nos. 7,309,605 and 6,610,545 that are being asserted against Precision
BioSciences.

Precision filed requests seeking reexamination of U.S. Patent No. 7,214,536 (the
`536 patent) and U.S. Patent No. 6,833,252 (the `252 patent) on the grounds that
these claims of these patents are obvious in view of a variety of references
which had not been previously considered by the patent examiners. On May 27,
2009, the PTO granted Precision`s requests and issued initial rejections of all
17 claims of the `536 patent, and 18 of 19 claims of the `252 patent.

In rejecting the claims of the `252 patent, the PTO concluded:

The terms "an I-SceIV site, an I-Csml site, I-Panl site, I-Scell
site, an I-CeuI site, an I-PpoI site, an I-SceIII site, an I
-CreI site, an I-TevI site, an I-TevII site, an I-TevIII site,
and an I-SceI site" are each interpreted to mean a segment of
DNA having a sequence that is recognized by the corresponding
Group I intron encoded endonuclease, which includes the
insertion site for the corresponding Group I intron. The terms
include the naturally-occurring endonucleases but not
genetically engineered endonucleases with altered specificities
or activities. (Emphasis added.)

The PTO went on to conclude:

"Group I intron encoded endonuclease site" is interpreted to mean a segment of DNA having a sequence that is recognized by a Group I intron encoded endonuclease and, as shown in Figure 6 of the '252 patent, that includes the insertion site for the corresponding Group I intron. (Emphasis added.)

Similar claim terms are used in the `605 patent and `545 patent that are the
subject of ongoing litigation between Cellectis and Precision.

The enzymes which are the basis of Precision`s Directed Nuclease Editor
technology are genetically-engineered endonucleases with altered specificities.
The recognition sites of these rationally-designed enzymes do not include the
intron insertion site of a naturally-occurring Group I intron encoded
endonuclease.

In rejecting all but one of the claims of the `536 patent and the `252 patent as
obvious, the PTO relied on a number of the same references that Precision
contends also render the asserted claims of the `605 patent and `545 patent
obvious or anticipated.

According to data released by the PTO for all inter partes reexaminations which
had been concluded since the procedure was first introduced in 1999 through
March 31, 2009, 73% of the reexaminations resulted in all issued claims being
canceled, and 93% of the reexaminations resulted in at least some issued claims
being canceled or amended.

Precision BioSciences is now evaluating whether or not it will request that
every patent in this family be reexamined, including those currently asserted
against Precision.

Interested parties can download a copy of the PTO`s office actions at:
www.precisionbiosciences.com/news.

About Precision BioSciences

Precision's mission is to utilize its engineered endonuclease technology to
become the world leader in the field of genomic molecular biology. Precision`s
proprietary Directed Nuclease EditorTM (DNE) technology enables the production
of custom genome editing enzymes that can insert, remove, modify, and regulate
essentially any gene in mammalian or plant cells.

Precision BioSciences has already produced hundreds of custom endonucleases for
partners and internal development that can precisely alter naturally occurring
sequences within genomes. Precision has successfully partnered its DNE
technology with several of the world`s largest agbiotech firms and is internally
developing applications in biological production and human therapeutics. For
additional information, please visit www.precisionbiosciences.com.

Precision BioSciences, Inc.
Chelsea Lynam, 919-314-5512

Copyright Business Wire 2009