The United States Patent and Trademark Office (PTO) is re-examining two currently issued US patents owned by the Institut Pasteur and the Universite Pierre et Marie Curie, and licensed to Cellectis SA. The two patents belong to a family of thirteen issued US patents, which includes US Patent Nos. 7,309,605 and 6,610,5 45 that are being asserted against Precision BioSciences.

Precision filed requests seeking reexamination of US Patent No. 7,214,536 (the '536 patent) and US Patent No. 6,833,252 (the '252 p atent) on the grounds that the 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 ICeuI site, an I-PpoI site, an I-SceIII site, an I-CreI site, an I-TevI site, an ITevII 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 stated that '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 specific ities. 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 per cent of the reexaminations resulted in all issued claims being cancelled, and 93 per cent of the reexaminations resulted in at least some issued claims being cancelled 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.

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 Editor (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.