IL-2-PE40 prevents the development of tumors in mice injected with IL-2 receptor expressing EL4 transfectant tumor cells.
A number of different immunotherapeutic reagents are currently being developed to target IL-2R for the treatment of leukemia, graft rejection, and certain autoimmune diseases. Previously, we have shown that IL-2-PE40, a chimeric protein composed of human IL-2 linked to the N-terminus of a truncated form of Pseudomonas exotoxin (PE), could effectively kill a variety of cell lines in vitro expressing either low, intermediate, or high affinity IL-2R. Here, we demonstrate that IL-2-PE40 can successfully retard or prevent the growth of a lethal ascites tumor or a solid tumor composed of EL4J murine thymoma cells transfected with the p55 murine IL-2R. The transfected line, EL4J-3.4, expresses 1,000 to 3,000 high affinity IL-2R. Survival extension in the ascites model was achieved by initiating treatment either after 4 to 6 h or within 5 days post-tumor injection in both athymic nude and C57BL/6 mice. Similarly, the growth of an aggressive s.c. solid tumor could also be inhibited. Extension of survival was not achieved either by using the truncated toxin alone not attached to IL-2 or by using an IL-2-PE40Asp553 mutant lacking a functional toxin. Survival extension was not caused by IL-2 activated NK or other host effector mechanisms as IL-2-PE40 was unable to prevent the receptor-negative EL4J parental line from forming a lethal ascites or a solid tumor. Thus, IL-2-PE40 is a potent, specific cytolytic reagent that may prove useful in the arsenal of anti-IL-2R immunotherapeutics.
Kozak
R W
RW
Division of Cytokine Biology, CBER, FDA, Bethesda, MD 20892.
Lorberboum-Galski
H
H
Jones
L
L
Puri
R K
RK
Willingham
M C
MC
Malek
T
T
Fitzgerald
D J
DJ
Waldmann
T A
TA
Pastan
I
I
D036002:ADP Ribose Transferases; D000818:Animals; D000970:Antineoplastic Agents; D001201:Ascites; D001427:Bacterial Toxins; D005098:Exotoxins / Q000008:administration & dosage*; D007274:Injections, Intraperitoneal; D007376:Interleukin-2 / Q000008:administration & dosage*; D051379:Mice; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000628:therapy*; D015375:Receptors, Interleukin-2 / Q000378:metabolism*; D011994:Recombinant Proteins; D016019:Survival Analysis; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A
D036002:ADP Ribose Transferases; D000970:Antineoplastic Agents; D001427:Bacterial Toxins; D005098:Exotoxins; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A