Synergistic antitumor activity of taxol and immunotoxin SS1P in tumor-bearing mice.
OBJECTIVE
To investigate the combined antitumor activity in mice of immunotoxin SS1P and Taxol.


METHODS
Immunodeficient mice were implanted with A431/K5 tumors expressing mesothelin. Established tumors were treated i.v. with immunotoxin SS1P alone, i.p. with Taxol alone, or with the two agents together. SS1P was radiolabeled with (111)In and used to study the effect of Taxol on its uptake by A431/K5 tumors.


RESULTS
Using doses at which either agent alone caused stabilization of tumor growth, the combination was synergistic causing long-lasting complete remissions in many animals. In contrast, synergy was not observed when the same cells were treated with these agents in vitro. Tumor uptake of (111)In-SS1P was not affected by treatment with Taxol.


CONCLUSIONS
The combination of Taxol and SS1P exerts a synergistic antitumor effect in animals but not in cell culture. This effect is not secondary to increased tumor uptake of the immunotoxin. Synergy could be due to improved immunotoxin distribution within the tumor or could involve factors released by other cell types in the tumors.
Zhang
YuJian
Y
Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892-4264, USA.
Xiang
Laiman
L
Hassan
Raffit
R
Paik
Chang H
CH
Carrasquillo
Jorge A
JA
Jang
Beom-Su
BS
Le
Nhat
N
Ho
Mitchell
M
Pastan
Ira
I
D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage* / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000494:pharmacology; D002277:Carcinoma / Q000188:drug therapy*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003131:Combined Modality Therapy; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D006801:Humans; D007274:Injections, Intraperitoneal; D007279:Injections, Subcutaneous; D000090204:Mesothelin; D051379:Mice; D008819:Mice, Nude; D017239:Paclitaxel / Q000008:administration & dosage* / Q000494:pharmacology; D013329:Structure-Activity Relationship; D023041:Xenograft Model Antitumor Assays
D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; C000715528:Msln protein, mouse; C474515:SS1(dsFv)PE38; D000090204:Mesothelin; D017239:Paclitaxel