Chemotherapeutic Profiles of Human Tumors Implanted in SCID Mice Showing Appreciable Inconsistencies with Those in Nude Mice

Sensitivities to antitumor drugs of human tumor xenografts (HTXs) implanted in C.B-17-scid and in BALB/cA-nu were compared to examine whether genetic backgrounds of immune deficiency of the host mice influenced the chemotherapeutic profiles of implanted tumors. In a total of 25 pairs of corresponding experiments with each host mouse strain (5 HTXs × 5 drug treatment groups), we obtained consistent results in 23 (92.0%) experiments consisting of 10 which were both significantly effective and 13 which were both ineffective, although the remaining two (8.0%) experiments showed inconsistent results. A human T-cell lymphoma cell line, LM-2-JCK, implanted in nude mice, was resistant to treatment with 65 mg/kg of cyclophosphamide, but this tumor showed sensitivity to the same treatment when implanted in either SCID mice or mice with a recombination activating gene 2 defect [BALB/cA-TgH(Rag2)], suggesting that the genetic immune background of the host mouse should not be overlooked as a factor affecting tumors.