Nevertheless, from a practical standpoint, these chemicals are similar in the sense that a pure sample of a single compund can be separated from broader chemical mixtures. An enantiomer can be purified from a racemate containing both spatial isomers (the d- and the l-isomers). Similarly, antibodies with binding specificity for a particular antigen can be purified from an antisera containing immunoglobulins of various antigen specificities.

Interesting, then, that patent law answers the following question for these chemicals in an entirely opposite manner:  Does a disclosure of a broader chemical mixture containing the specific chemical (one particular enantiomer, or an antibody with a defined antigen specificity) anticipate the specific chemical?

More than two years ago, the Court of Appeals for the Federal Circuit told us that the answer is “yes” for antibodies. This week, we learned that the answer is “no” for enantiomers.

Consider this – this week, in Sanofi v. Apotex, the Court of Appeals for the Federal Circuit flatly rejected an argument that the disclosure of a racemate, along with general statements indicating that “the compounds have enantiomers and that the enantiomers are included in the invention,” anticipated the claim to the separated enantiomer. The court noted the strict nature of anticipation law, which requires a “specific description as well as enablement of the subject matter at issue” before anticipation exists. In this case, mere knowledge that a separation can be conducted is not anticipation: “The knowledge that enantiomers may be separated is not ‘anticipation’ of a specific enantiomer that has not been separated, identified, and characterized.” Enablement was troublesome, too, because of “the known difficulty of separating enantiomers….”

Two years ago, the court considered the anticipatory effect of a disclosure of an antisera to be completely different. In Nichols Institute v. Scantibodies Clinical Laboratory, the court concluded that the disclosure of an antisera (the general mixture of immunoglobulins) anticipates a specific antibody isolated from the antisera because the antisera inherently discloses the antibody. “We also hold…that the abstract anticipates the asserted claims, because no reasonable juror could have found that the abstract does not inherently disclose the claimed antibody.” Enablement didn’t present a significant issue, apparenly because antibodies can be separated from antisera using well-known purification/separation techniques.

The distinction between the two cases appears to lie in the purification techniques.  Antibody purification is carried out according to “well-known” techniques (I can attest to this), while there is a “known difficulty of separating enantiomers.” With this in mind, it seems likely that Nichols Institute represents the eventual destination for enantiomers – once separation techniques become well-known, the disclosure of the racemate will likely anticipate the separated enantiomer just as the disclosure of an antisera anticipates a specific antibody separated from the antisera.

For now, though, the “known difficulty” of separating enantiomers from the racemate leaves us with Sanofi.