Y. Kohchi et al. / Bioorg. Med. Chem. Lett. 17 (2007) 2241–2245
Monkey
2245
Mouse
brain
heart
lung
liver
pancreas
spleen
kidney
stomach
duodenum
jejunum
illeum
colon
rectum
S.I.
L.I.
bone marrow
pasmal
Colo205
0
1
2
3
4
5
1.0
0.8
0.6
0.4
0.2
0
( nmol (DMDC) / mg protein / min )
( nmol (DMDC) / mg protein / min )
Figure 8. The results of level of DMDC by crude enzyme extracts from mouse and monkey tissues.
hematopoietic progenitor cells, compound 23 was quite
stable. Thus, in vitro proof-of-concept of the tumor-ac-
tivated prodrugs was achieved.
vs normal tissue including hematopoietic progenitor
cells) performed. A general concern with the prodrug
approach is species difference in prodrug activation since
the absolute enzyme levels in all human tissues are
unknown. In the case of compound 23, some species
difference was observed between mice and monkeys.
Further investigation is needed to assure product safety
and efficacy for clinical development of this type of
prodrug.
The tumor selective conversion of compound 23
(50 lM) to DMDC was further examined with extracts
of COLO 205 human colon cancer xenograft that ex-
pressed MDP and was compared with extracts of vari-
ous normal tissues from mice and monkeys (Fig. 8).
Compound 23 was efficiently converted to DMDC in
COLO 205, whereas its conversion was very low in other
normal tissues from mice. On the other hand, among the
monkey tissues examined, the level of DMDC was much
higher in kidney than, and nearly equal in jejunum and
ileum to, that in COLO 205.
References and notes
1. Shimma, N.; Umeda, I.; Arasaki, M.; Murasaki, C.;
Masubuchi, K.; Kohchi, Y.; Miwa, M.; Ura, M.; Sawada,
N.; Tahara, H.; Kuruma, I.; Horii, I.; Ishitsuka, H. Bioorg.
Med. Chem. Lett. 2000, 8, 1697.
2. Ishitsuka, H.; Shimma, N.; Horii, I. Yakugaku Zasshi 1999,
119, 881.
3. Hattori, K.; Kohchi, Y.; Oikawa, Nobuhiro; Suda, H.;
Ura, M.; Ishikawa, T.; Miwa, M.; Endoh, M.; Eda,
H.; Tanimura, H.; Kawashima, A.; Horii, I.; Ishit-
suka, H.; Shimma, N. Bioorg. Med. Chem. Lett. 2003,
13, 867.
4. (a) Takenuki, K.; Matsuda, A.; Ueda, T.; Sasaki, T.; Fujii,
A.; Yamagami, K. J. Med. Chem. 1988, 31, 1063; (b) Ueda,
T.; Matsuda, A.; Yoshimura, Y.; Takenuki, K. Nucleosides
Nucleotides 1989, 8, 743; (c) Matsuda, A.; Takenuki, K.;
Tanaka, M.; Sasaki, T.; Ueda, T. J. Med. Chem. 1991, 34,
812; (d) Yamagami, K.; Fujii, A.; Arita, M.; Okumoto, T.;
Sakata, S.; Matsuda, A.; Ueda, T.; Sasaki, T. Cancer Res.
1991, 51, 2319.
Species difference in tissue distribution of MDP is of con-
cern for development of oral compound 23 for human.
Further investigation is required to identify prodrugs
with less species difference in enzymatic activation.
In conclusion, this study demonstrates the gene expres-
sion profiling of tumor and normal tissues including
hematopoietic progenitor cells by DNA microarray is
an effective approach in identifying enzymes for the
design of tumor-activated prodrugs of cytotoxic agents.
We designed compound 23 which was selectively con-
verted to an active drug, DMDC, by MDP-positive
tumor tissues. The desired tumor selective conversion
was clearly demonstrated in vitro from the cytotoxicity
assays (tumor cells with high vs low MDP), cell free
enzyme assays, and tissue conversion assays (tumor
5. Ishitsuka, H.; Okabe, H.; Shimma, N.; Tsukuda, T.;
Umeda, I., PATENT WO 2003043631 A2, 2003.