The opinion of the court was delivered by: JACKSON
1. Plaintiff, as assignee of Carlo Concilio, Piero Lanza and Mario Preti, brought this action under 35 U.S.C. § 145, seeking a judgment from this Court authorizing the defendant, Commissioner of Patents, to issue a patent to plaintiff containing Claims 2, 3, 4 and 7 of Concilio et al. application Serial No. 101,656, filed April 10, 1961, entitled "Threo-3-(p-methylsulfonylphenyl) -2- dichloroacetamido-1-(aminoacetoxy)- 3 -propanol and Preparation Thereof."
2. The application in suit relates to an ester (identified in the title of the application) and certain derivatives thereof, which are therapeutically useful as antibiotics. This ester is also known as thiophenicol glycinate. The latter is much less bitter than thiophenicol, its alcohol progenitor.
3. Claim 2 is representative and reads as follows:
D- (-) - threo - 3 -(p-methylsulfonylphenyl) -2- dichloroacetamido -1- (aminoacetoxy)- 3 -propanol.
The other claims stand or fall with Claim 2.
4. The Patent Office Board of Appeals affirmed the Examiner's rejection of the claims of the Concilio et al. application, on the ground of unpatentability over the combined teachings of Belgian (Zambon) patent No. 572,685, granted November 29, 1958, and Rebstock et al. U.S. patent No. 2,717,268, issued September 6, 1955, particularly in view of the prior art knowledge admitted in the Concilio et al. specification that thiophenicol itself is a broad spectrum antibiotic.
5. Zambon discloses as prior art (with respect to the invention disclosed therein) that the antibiotic chloramphenicol is characterized by its bitter taste and slight water solubility, and that some of its esters (such as those produced with palmitic, benzoic and cinnamic acids) are insoluble and tasteless. This patent further discloses that a new water-soluble ester, chloramphenicol glycinate, is useful as a parenterally administered antibiotic in cases where an effective water-soluble chloramphenicol derivative is needed, such as for injection therapy.
7. Rebstock et al. U.S. patent No. 2,717,268 discloses a process for the preparation of substituted 1-phenyl-2-dichloroacetamidopropane-1, 3-diol compounds where the R substituent (at the p-phenyl position) is a hydrogen, nitro, phenyl, CH (3)S, CH (3)SO or CH(3)SO(2) substituent. The products of the Rebstock process are disclosed as useful as therapeutic agents per se. When R is nitro and CH(3)SO(2), the diols, respectively, are chloramphenicol and thiophenicol.
8. Chloramphenicol and thiophenicol are alcohols and are therapeutically useful as antibiotics, but both have poor water solubility. Chloramphenicol glycinate and thiophenicol glycinate, the respective glycine esters of those alcohols, are also useful as antibiotics, and have good water solubility. Rebstock discloses the two free alcohols and their therapeutic utility. Zambon discloses chloramphenicol glycinate. Thiophenicol glycinate, the compound of Claim 2, is novel and useful. The structural formulas for thiophenicol glycinate and chloramphenicol glycinate are identical, except that the p-phenyl substituent of the former is a methylsulfonyl (CH(3)SO(2)) group, while the latter has a nitro (NO (2)) group at the same point. The same structural difference, of course, exists in the free diols.
9. It would have been obvious to one having ordinary skill in the drug art that the poor water solubility of thiophenicol could be overcome by forming the glycine ester of thiophenicol, in view of the superior water solubility of chloramphenicol glycinate to that of chloramphenicol itself (taught by Zabon) and the therapeutic equivalence of chloramphenicol and thiophenicol (taught by Rebstock).
10. Plaintiff's expert witness, Dr. Ferrari, Director of Medical Research for Zambon S.p.A., testified at the trial that thiophenicol itself "is slightly less bitter than chloramphenicol and possibly not as long lasting * * *." Consequently, it would be reasonable to predict, on the basis of this knowledge, that thiophenicol glycinate should be at least "slightly less bitter" than chloramphenicol glycinate, and that the bitter ...