Analogues of camptothecin, their use as medicaments and the...

Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...

Reexamination Certificate

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Reexamination Certificate

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06815546

ABSTRACT:

Camptothecin is a natural compound which has been isolated for the first time from the leaves and the bark of the Chinese plant called
camptotheca acuminata
(see Wall et al. J. Amer. Chem. Soc. 88:3888 (1966)). Camptothecin is a pentacyclic compound constituted by an indolizino[1,2-b]quinoline fragment fused with an &agr;-hydroxylactone with six members. The carbon in position 20 which carries the &agr;-hydroxy group is asymmetrical and confers a rotatory power on the molecule. The natural form of camptothecin has an absolute “S” configuration as regards the carbon 20 and corresponds to the following formula:
Camptothecin has an anti-proliferative activity in several cancerous cell lines, including the cell lines of human tumors of the colon, lung and breast (Suffness, M et al: The Alkaloids Chemistry and Pharmacology, Bross A., ed., Vol. 25, p. 73 (Acedemic Press, 1985)). It is suggested that the anti-proliferative activity of camptothecin is related to its inhibitory activity on DNA topoisomerase I.
It has been indicated that &agr;-hydroxylactone was an absolute requirement both for the in vivo and in vitro activity of campotothecin (Camptothecins: New Anticancer Agents, Putmesil, M et al, ed., p. 27 (CRC Press, 1995); Wall M. et al, Cancer Res. 55:753 (1995); Hertzberg et al, J. Med. Chem. 32:715 (1982) and Crow et al, J. Med. Chem. 35:4160 (1992)). The present invention relates to a new class of compounds of camptothecin, in which a &bgr;-hydroxylactone replaces the natural &agr;-hydroxylactone of camptothecin. The compounds according to the present invention present a powerful biological activity which is unexpected with regard to the state of the prior art.
Therefore a subject of the invention is new analogues of camptothecin which differ from all known derivatives of camptothecin in the sense that they contain &bgr;-hydroxylactone (or its open hydroxycarboxylic form) instead of an &agr;-hydroxylactone (or its open hydroxycarboxylic form); or a pharmaceutically acceptable salt of one of the latter. By derivative of camptothecin is meant a compound having the same structural skeleton as that of camptothecin (i.e. an indolizino[1,2-b]quinoline fragment fused with an &agr;-hydroxylactone with six members), with or without other chemical substitutions on the skeletal structure. Different derivatives of camptothecin are well known by specialists, as described hereafter. By &bgr;-hydroxylactone is meant a lactone which contains an additional carbon atom between the carbon of the carboxyl and the &agr;-carbon carrying the hydroxyl group in the &agr;-hydroxylactone.
An analogue of camptothecin according to the invention can therefore contain substitutions on the indolizino[1,2-b]quinoline fragment (for example in order to improve the solubility of the compound), or on the open or closed &bgr;-hydroxylactone (for example in order to improve the stability of the compound). Examples of substitutions on the closed &bgr;-hydroxylactone include an alkyl substitution (for example ethyl) on the &bgr;-carbon. Examples of substitutions on the open &bgr;-hydroxylactone include alkyl substitutions on the &bgr;-carbon, substitutions (for example an amidation) on the resultant carboxylic acid and substitutions (for example an esterification) or suppressions of the resultant hydroxyl group.
Preferred &bgr;-hydroxylactone camptothecin analogues are notably those in which the pentacyclic skeletton is substituted at least once by an halogen atom in any of positions 8, 9, 10, 11 or 12.
The invention first relates to compounds of general formula (A
1
) or (A
2
)
in racemic or enantiomeric form or any combinations of these forms, in which
Z
1
represents a lower alkyl, a lower alkenyl, a lower alkynyl, a lower haloalkyl, a lower alkoxy lower alkyl or lower alkylthio lower alkyl;
Z
2
, Z
3
, Z
4
, Z
5
and Z
6
represent, independently,
 i) H, halo, lower haloalkyl, alkyl containing 1 to 12 carbon atoms optionnally substituted by one or more halo radicals indentical or different, lower alkenyl, cycloalkyl, cycloalkyl lower alkyl, cyano, lower cyanoalkyl, nitro, lower nitroalkyl, amido, lower amidoalkyl, hydrazino, lower hydrazinoalkyl, azido, lower azidoalkyl, lower alkyl lower sulphonylalkyl, —(CH
2
)
m
NZ′
6
Z′
7
, —(CH
2
)
m
OZ′
6
, —(CH
2
)
m
SZ′
6
, —(CH
2
)
m
CO
2
Z′
6
, —(CH
2
)
m
NZ′
6
C(O)Z
8
, —(CH
2
)
m
C(O)Z
8
, —(CH
2
)
m
OC(O)Z
8
, —O(CH
2
)
m
NZ′
6
Z′
7
, —OC(O)NZ′
6
Z′
7
, —OC(O)(CH
2
)
m
CO
2
Z′
6
, —OSO
2
Z
7
, —(CH
2
)
m
N(CH
3
)(CH
2
)
n
NZ′
6
Z′
7
, —(CH
2
)
m
OC(O)NZ′
6
Z′
7
, —(CH
2
)
m
S(O)
q
Z
11
, —C(CH
2
)
m
P(O)Z
12
Z
13
, —(CH
2
)
2
P(S)Z
12
Z
13
, —(CH
2
)
m
SiZ′
11
Z′
12
Z′
13
; or ii) —(CH
2
)
n
[N═X], —OC(O)[N═X], —(CH
2
)
m
OC(O)[N═X], aryl or lower arylalkyl, each substituted (i.e. substituted between once and four times on the aryl group or the heterocycle) or non substituted in which the substituent is a lower alkyl, lower arylalkyl, halo, hydroxy, —OCF
3
, nitro, amino, lower alkylamino, di(lower alkyl)amino, lower haloalkyl, lower hydroxyalkyl, lower alkoxy or lower alkoxy lower alkyl or iii) Z
3
and Z
4
or Z
4
and Z
5
form together a chain with 3 or 4 members in which the elements of the chain are selected from the group constituted by CH, CH
2
, O, S, N or NZ
9
;
Z
7
represents a lower alkyl radical optionnally substituted by one or more halo radicals identical or different, or an aryl optionnally susbtituted by one or more lower alkyl radicals identical or different;
Z′
6
and Z′
7
represent, independently, i) H, a lower alkyl, lower hydroxyalkyl, lower alkyl lower aminoalkyl, lower aminoalkyl, cycloalkyl, cycloalkyl lower alkyl, lower alkenyl, lower alkoxy lower alkyl, lower haloalkyl, or ii) aryl or lower arylalkyl, each substituted (i.e. substituted between once and four times on the aryl group) or non substituted in which the substituent is a lower alkyl, halo, nitro, amino, lower alkylamino, lower haloalkyl, lower hydroxyalkyl, lower alkoxy or lower alkoxy lower alkyl;
Z
8
represents i) H, a lower alkyl, lower hydroxyalkyl, amino, lower alkylamino, lower alkyl lower aminoalkyl, lower aminoalkyl, cycloalkyl, cycloalkyl lower alkyl, lower alkenyl, lower alkoxy, lower alkoxy lower alkyl, lower haloalkyl, or ii) aryl or lower arylalkyl, each substituted (i.e. substituted between once and four times on the aryl group) or non substituted, in which the substituent is a lower alkyl, halo, nitro, amino, lower alkylamino, lower haloalkyl, lower hydroxyalkyl, lower alkoxy or lower alkoxy lower alkyl;
Z
9
represents i) H, a lower alkyl, lower haloalkyl, or ii) aryl or lower arylalkyl, each substituted or non substitutued in which the substituent is lower alkyl, halo, nitro, amino, lower alkylamino, lower haloalkyl, lower hydroxyalkyl, lower alkoxy or lower alkoxy lower alkyl;
Z
10
represents i) H, a lower alkyl, lower haloalkyl, lower alkoxy, or ii) aryl substituted (i.e. having one to four substituents on the aryl group)or non substituted in which the substitutent is lower alkyl, lower haloalkyl, lower hydroxyalkyl or lower alkoxy lower alkyl;
Z
11
represents a lower alkyl, aryl, —(CH
2
)
m
OZ
14
, —(CH
2
)
m
SZ
14
, —(CH
2
)
2
NZ
14
Z
15
or —(CH
2
)
m
[N═X];
Z
12
and Z
13
represent, independently, a lower alkyl, aryl, lower alkoxy, aryloxy or amino;
Z′
11
, Z′
12
and Z′
13
represent, independently, H or a lower alkyl radical;
Z
14
and Z
15
represent, independently, H, lower alkyl or aryl;
Z
16
represents H or —OZ
21
;
Z
17
represents —OZ′
6
or —NZ′
6
Z′
7
;
Z
18
and Z
19
represent, independently, H, halo, lower alkyl, lower alkoxy or hydroxy;
Z
20
represents H or halo;
Z
21
represents H, a lower alkyl, —CHO or —C(O)(CH
2
)
m
CH
3
;
Z
p
represents H or an easily cleavable group preferably chosen from the groups corresponding to the formula —C(O)—A—NZ
22
Z
23
, in which A represents a linea

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