The affinities of the polyclonals then in use in commercial AFP assays
necessarily had to be sufficient to detect the minimum clinically
significant concentration of AFP, namely, 20 nanograms of AFP per
liter. That means that the affinities of those commercial polyclonals
9 8
would be 3.3x10 liters per mole or as low as 3.3x10 liters per mole.
An affinity of “at least about 10 liters per mole” is certainly8
“comparable to 3.3x10 liters per mole.8
Engvall reply brief, pp. 17-18.
The problem with this argument is that Engvall has not directed us to evidence of sufficient
weight to prove by even a preponderance of the evidence that the inventors had a contemporaneous
appreciation that 20 nanograms per liter was the clinically significant concentration of AFP or that
detecting 20 nanogram per liter was a recognized goal of their research. Engvall has not identified
any documentary evidence that shows this was an appreciated goal at the time of the alleged
conception. The testimony of witnesses, speaking long after the fact from memory in regard to past
transactions, in the absence of contemporaneous documentary or physical evidence, has been held to
be of little probative value. Lockheed Aircraft Corp. v. United States, 553 F.2d 69, 75, 193 USPQ
449, 455 (Cl. Ct. 1977).
The reference to Holbeck’s and Hayman’s testimony (e.g. Engvall reply brief, p. 17, note 16)
does not help Engvall’s case. The referenced testimony, while apparently indicating that Holbeck and
Hayman were aware that high affinity antibodies were desired, does not indicate Holbeck’s and
Hayman’s understanding of the meaning of “high affinity” or that they associated the phrase “high
affinity” with an ability to detect AFP in a concentration of 20 nanograms per liter or with an affinity
constant for AFP of 3.3x10 liters per mole. Thus, the statements of the Engvall inventors as to what8
they meant by “high affinity” antibodies are not corroborated.
The only testimony to which we have been directed that arguably correlates “high affinity”
with “at least about 10 liters/mole” is that of John Langone. In particular, Engvall refers to8
Langone’s testimony appearing at ER 3501-11. Engvall Brief, p.78. Langone there expresses his
opinion as to the affinity constant of the antibodies used in example 1 from Engvall’s specification.
For example, Langone states:
I feel confident in claiming that the binding affinity of both antibodies,
including the antibody used to coat the plastic surface, in example 1
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