Appeal No. 2005-1797 Page 8
Application No. 09/954,975
attempt to distinguish (Reply Brief, page 8), gallium “in and of itself” from gallium
containing compositions, appellants’ claim 11 is open to include gallium
containing compositions as taught by Collery. Further, appellants fail to direct
our attention to any evidence on this record to suggest that the gallium
compositions within the scope of their claims exhibited any unexpected benefit
over that taught by the combination of prior art relied upon by the examiner. In
this regard, while appellants remain hesitant to acknowledge it, Collery discloses
that the gallium containing compositions disclosed therein exhibit anti-viral
activity.
Further, while appellants make reference to what they characterize as a
“low EC50/IC50 ratio”, they make no attempt on this record to explain to what this
“ratio” refers. Accordingly, we offer the following. We understand IC50 to refer to
“the half maximal inhibitory concentration.”5 Stated differently IC50 represents the
concentration of a drug that is required for 50% inhibition of viral replication in
vitro. According to the data provided in Table VII (column 16) of Collery, all but
one of the gallium compositions exhibited a higher IC50 than AZT. As for EC50,
we understand this term to refer to “the concentration of a compound that is
required to obtain 50% of the maximum effect.”6 Stated differently, EC50
represents the plasma concentration required for obtaining 50% of the maximum
effect in vivo. As seen in Collery’s Table VII, a higher plasma concentration is
required for the gallium compositions to obtain their maximum effect relative to
5 See “IC50” at Wikipedia, http://en.wikipedia.org/wiki/IC50.
6 Id. n. 5.
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