By Christopher P. Singer --
As previously reported on Patent Docs, the biotechnology, chemical, and pharmaceuticals technology groups at the U.S. Patent Office held their quarterly customer partnership meeting on June 13, 2007. While the stated purpose of the meeting was merely to encourage dialog between practitioners, patent applicants, and the Office (i.e., not to announce PTO policy), the discussions did provide a helpful insight as to how these Art Units approach certain issues.
One discussion focused on enablement issues under 35 U.S.C. § 112 as applied to the examination of claims relating to antibodies. Larry R. Helms, Supervisory Patent Examiner for Art Unit 1643 presented a discussion of common enablement issues that Examiners encounter during examination of antibody inventions. After providing some general background discussion on antibody technology, Mr. Helms presented examples of three types of antibody claims and typical reasoning as to why each claim was enabled or not enabled, given particular disclosure in the specification, and the state of the prior art (typically referenced to around the late 80's to early 90's).
1st Example:
Claim 1: An isolated antibody that binds to human antigen X, said antibody comprises a heavy chain variable domain comprising the 3 CDRs in SEQ ID NO:1 and a light chain variable domain comprising the 3 CDRs in SEQ ID NO:2.
This claim would be ENABLED when the specification discloses:
(a) antigen X from human tissue;
(b) antigen X is over-expressed in, e.g., cancer cells, compared to normal cells;
(c) an antibody that binds antigen X and contains SEQ ID NOs:1 and 2;
(d) explicit disclosure of humanized and chimeric antibodies; and
(e) examples of detection of cancer in human subjects with an antibody that binds antigen X.
2nd Example:
Claim 1: An isolated antibody that binds to human antigen X, said antibody comprises a heavy chain variable domain comprising SEQ ID NO:1.
Claim 2: An isolated antibody that binds to human antigen X, said antibody comprises a light chain variable domain comprising SEQ ID NO:2.
These claims would be ENABLED when the disclosure contains the same information noted for Example 1 above.
3rd Example:
Claim 1: An isolated antibody that binds to human antigen X, said antibody comprises a heavy chain variable domain and a light chain variable domain, said heavy chain variable domain comprises the CDR3 in SEQ ID NO:1.
This claim would NOT be ENABLED when the specification discloses:
(a) a series of antibodies with specific pairing (i.e., non-random) of VH and VL domains, that bind antigen X;
(b) the VH domains are highly homologous to each other and share identity over a large portion of the other CDR and framework regions;
(c) the VL sequences are highly homologous to each other in the framework and CDR regions;
(d) a suggestion that it was well established in the art at the time of the invention that the CDR3 region alone can determine the specificity of an antibody.
Mr. Helms' rationale behind the last example is that the prior art methods (ca. late 90's early 2000's) fail to generate antibodies by retaining solely the CDR3 region of the VH domain and randomizing the remainder for the VH and VL sequences. He also characterized the art as indicating that, while important, CDR3 is not solely responsible for antigen binding, as a number of references describe that all six CDR regions (and sometimes framework regions) provide important contacts with the antigen. Thus, the full scope of the claim in Example 3 is not enabled. Therefore, if an applicant wishes to pursue claims similar to those in Example 3 above, it seems that in order to meet the enablement requirement the applicant will need to present data to the Office, either in the form of examples in the specification or through 132 declarations, that demonstrate that CDR3 (or another portion of the VH or VL sequence) can confer antigen specificity to a randomized sequence.
Note to Readers: This is the first in a series of articles regarding selected presentations from the June 13, 2007 quarterly biotechnology/chemical/pharmaceuticals customer partnership meeting. The second article in the series is entitled "Restriction Practice For Product Inventions in The Biotech, Chemical & Pharma Arts."
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