30Aug 2022

{3 minutes to read}  In a recent case, the Federal Circuit found that the claim language at issue was ambiguous, and relied on the prosecution history for claim construction without requiring the prosecution history to reveal a “clear and unmistakable disclaimer” of the plain meaning of the claims.

Claim 1 is representative of the claims of the case:

  1. A method for enhancing the condition of unbroken skin of a mammal by reducing one or more of wrinkling, roughness, dryness, or laxity of the skin, without increasing dermal cell proliferation, the method comprising topically applying to the skin a composition consisting of a concentration of adenosine in an amount effective to enhance the condition of the skin without increasing dermal cell proliferation, wherein the adenosine concentration applied to the dermal cells is 10-4 M to 10-7 M.

The patent specification described human skin as a surface layer called “the epidermis” with a deeper layer called “the dermis.” Claim 1 described applying a composition to the skin surface topically, reaching a certain concentration in the dermal cells below the surface.

The Federal Circuit reviewed the claim construction de novo, and in this case noted that the relevant claim language was not plain on its face, but rather contained evident uncertainties that weighed against the plaintiff’s construction. On the other hand, the court found that the specification and prosecution history showed that the “wherein” clause should have been read to refer to the concentration of adenosine in the composition applied to the skin’s surface. According to the Federal Circuit, the specification described compositions having adenosine concentrations of 10-4 M to 10-7 M.

The specification did not describe specific numerical molar concentration figures … after penetration through the skin into the dermis, or a measurement of concentration as an amount of adenosine per unit of volume of dermal cells.

The last clause was added during prosecution based on a dependent claim.

The applicants distinguished the invention from prior art references “in which concentrations are measured before application to the skin, with no suggestion of a difference in the location of concentration measurement.”

The examiner’s reasons for allowance stated: The “[i]nstant claims are directed to a method of enhancing the condition of unbroken skin . . . where the method comprises administering adenosine, at a concentration of 10-4 M to 10-7 M, to the skin.”

Thus, the Federal Circuit concluded that the prosecution history required that the wherein clause’s reference to the recited concentrations being applied to the dermal cells be read as referring to concentrations of the composition applied to the skin’s surface.

In conclusion, if applicants have specific concerns about the examiner’s reasons for allowance, they should consider filing comments to clarify the record.

Silvia Salvadori, PhD Silvia Salvadori, PhD
Salvadori Law
Please contact me at silvia@salvadorilaw.com with questions or comments.