Further observations on the efficacy of phenylalanine mustards against mouse melanoma.

Four phenylalanine nitrogen mustards were tested against the S91 Cloudman mela noma in young male mice. Two of the mustards carried the di (2-chloroethyl) amino group in the meta position but differed in respect to the location of the amino group in the alanine side chain. Likewise, two of the mustards carried the di(2-chloroethyl)amino group in the para position, again differing, however, in location of the amino group in the alanine side chain. The most effective of the four was the meta mustard derivative of phenyl-DL-aalanine. The two isomers containing the side chain amino group in the beta position instead of the alpha were of low toxicity and could be employed at much higher dosage levels but were of relatively low potency. In general, the observations reported confirm the findings of Gram, Mosher, and Baker on the appreciably higher potency of the alpha meta mustard as compared with the known potency of the alpha para mustard.