CA2061993A1

CA2061993A1 - Fucose-bearing cytostatics

Info

Publication number: CA2061993A1
Application number: CA002061993A
Authority: CA
Inventors: Hans-Georg Lercehn; Joerg Baumgarten; Norbert Piel; Jens-Peter Lorentzen; Horst-Peter Antonicek; Hans-Joachim Kabbe
Original assignee: Individual
Current assignee: Bayer AG
Priority date: 1991-02-27
Filing date: 1992-02-27
Publication date: 1992-08-28
Also published as: FI920834A0; HUT60283A; FI920834A; CA2060746A1; HU9200637D0; DE4106101A1; JPH0578394A; EP0501250A1

Abstract

Fucose-bearing cytostatics ABSTRACT OF THE DISCLOSURE
The heterocyclic amine 1 (batracylin) exhibits excellent anti-tumor action in the colon 38 model in the mouse; this model is regarded as representative of the action against colonic cancer. The anti-tumour action can be improved by labeling of the Batracylin with fucose.

LeA28 142

Description

~9~

The heterocyclic amine 1 tbatracylin) exhibits excellent anti-tumour action in the colon 38 model in the mouse;
this model i8 regarded as representative of the ac~ion against colonic cancer. (US 4,757,072).
o R-NH ~ IR- H VS 4,757,072 ~ 2R= ~ ~S 4,180,343 The action of batracylin i8 greatly restricted by its low solubility in water-containing solvent~, which, inter alia, makes the preparation of ~olution~ which can be administered difficult.

This handicap was overcome by the acylation of 1 with natural amino acids to give the acyl derivative~ 2 (US 4,180,343). Compounds of the type 2 are cleaved by peptidases in human serum to give 1 and are therefore ~ust as activla as 1 and have bet~er water solubility.

In the context of further investigations, it has now 6urprisingly been found that novel peptLde and glycopeptide con~ugate~ of 1, which are not prodrugs, exhibit A cytostatic nction, which is equal to that o~

Le A ~_142 - 1 -f:j ~3 batracylin 1 or even surpasse~ this, on SW 480 cell line~.

Interestingly, the linkage of ~-L-fuco~e derivatives to peptide con~ugates of 1 led to active compounds, while all other glycopeptide derivative te3ted were inactive.

Moreover, it wa~ possible to show that the desir~d action could be reproduced by linkage of ~-L-fucose to inactive peptide con~ugates.

The new derivativeæ are distinguished by more favourabls ~olvent properties, and possibly better ~electivities with respect to the action can be expected for ~-L-fuco~e con~ugates.

The new compounds are described by the following general formula:

[R]n AAl - AA2 ~ - C

where C = a cytostatic, preferably Le A 28 142 - ~ -R = H3C ~ X B

X = ~lkylene or arylene Y = CO, NH, O
B = a bond or diacyl radical of a dicarboxylic acid, AA1 = is a n~tural amino acid radical in the L- ox D~configuration or a bond. If AA1 also carrie~
other functional groups, these can be deblocked or protected by known protective groups or linked to B in amide fashion. Suitable protective groups are, for example, benzyloxycarbonyl, fluorenyl-methoxycarbonyl, t-butyloxycarbonyl, benzyl or tert.-butyl.

AA2 = i8 a natural amino acid in the D- or L-configura-tion or a bond. If AA2 also carries other func-tional groups, the~e can be deblocked or protec-ted by known protective groups or linked to B in amide fashion. Suitable protective groups are, forexample, benzyloxycarbonyl, fluorenylmethoxy-carbon~l, t-butyloxycarbonyl, benzyl or tert.-butyl.

n - 0, 1 or 2.

Preferred compounds are those in which X ~ p-phenylene or (CH2)m, where m can be 1-20, prefernbly 1-10, Le A 2B 142 - 3 -Y = CO or NH, B - a bond or the radical of a C3-C6-dicarboxylic acid, n = 0, 1 or 2.

The following are very particularly preferred for AA~ amino acid radicals having acidic or ba~ic side chains, or a bond for A~ ~mino acid radicals such as Ala, Val, Leu, Ile, Nva, Gly, Phe tD- or L-configuration), which are linked to the heterocycle and to AA1 in amide fashion.
for R the following ~-L-fucose derivatives:
Rl=
o H3C ~ O ~ O - CH2- C
~ OH
HO
B-L-Fuc-~yac-R2=

H3C ~ o ~ O - (CH2)6 C
~ OH
HO
B-L-Fuc-Hycapr-R3=
O O
H3C 1--o ~r o ~ NH--C CH2--CH2--C
~ OH
HO
~L-Fuc-pAP-Suc-Le A 28 142 - 4 -,i 6~

HO OH ~ NH - C -(CH2~3 - C
R5= B-L-Fuc-pAP-GIut-H3C 1 o ~r ~ NH
~ OH
HO
R6= B-L-Fuc-pAP-H3C ~ O ~ O - (CH~ NH
~ OH
HO
B-L-Fuc-~AHex-R7=
O O
Il 11 H3C ~ O ~ O - (CH~- NH - C - (CH2)2- C
~ OH
HO
B-~Fuc~AHex-Suc-Instead of batracylin, other cytostatLcs or their derivative~ can also be employed, ~uch a~, for example Methotrexate~

H ~ C-CH2 CH2-CH NH-C ~ N - CH ~ N ~ NH2 Le A 28 142 - 5 -S3 ~ .t Nimestin: ~
CH2-NH-CO-N - CH2 - CH2- Cl Daunorubicin:
O OH
~ r: I~COHH3 H3C ~ O

HO
Abbreviations nnd aeneral point~

All amino acids are shown in the IUPAC-IUB abbreviation (3 let~er code).

If no configuration i8 given, they are in the L-form.

Protective groups are abbreviated in the generally conventional notation~.

Other abbreviAtionss ~-L-Fuc ~-~-fuco~yl Hyac hydroxyacetate Le A 28 142 - 6 -~ .J~

Hycapr ~-hydroxycaprylata pAP p-aminophenyl Suc 8UCC inyl Bzl benzyl z benzyloxycarbonyl Fmoc Fluorenylmethoxycarbonyl Boc t-butyloxycarbonyl DMF N,N-dimethylformamide Ac acetyl Hex hexyl Glut glutarate ~-AHex ~-amino-hexanyl(1) DCC dicyclohexylcarbodiimide HOSu N-hydroxysuccinimide General _synthesis__procedure for batracylin-peptide con~,uQates ~-L-Fucosides containing ~-hydroxycarboxylic actd esters or ~-hydro~yalkylamines suitably protected on the amino function are advantageously prepared from peracylated L~
fucose using Lewis acids such as ~CH3)3SiOS02CF3, BF3-0Et2,ZnCl2 etc. or from acylated L-fucosyl halides using heavy metal salts, preferably silver or ~ercury compounds, in a ~uitable solvent such as, for example, CH2Cl2, CHCl3, toluene etc. To prepare the target compounds 4, the protected intermediates 3 are deblocked in the usual way.
The ~-carboxylic acid fucos~des can then be prepared by hydrolysis of the acyl group~ and of the carboxylic ~cid Le A 28 142 - 7 -2 ~ ~f~j3 est~r group~ and subsequent liberation of the carboxylic acids from their salts. The ~-amino fuco-Rides are prepared by liberation of the ~-amino compQund from the blocked derivativeQ and subsequent hydrolysis of the acyl protective groups or using the reverEe sequence. The pure ~arget compounds 4 are advantageou~ly obtained by crystallisation or chromatographic methods.
H3C ~ ~ R2 ~ --C--Rl +HO(CH2)nR3 ____~
Rl- C - O O - C - Rl o ll 11 O O

H3C 1-- ~r O(CH2) n -R3 Rl = Alkyl, Alyl ~ ~ C - Rl R2= H~ogen,O-Acyl Rl C ~ C O R3=CoOR,NR'R"
O O Rl n=2-20 H3C 1-- ~r O(CH2) nR
~,OH
HO
4 R~cooH~NH2 Le A 2~ 142 - 8 -Alternatively to 4, ~he ~-L-fucose derivative 5 which is obtained by hydrogenoly~is from the commercial ~-L-fucose-p-nitrQphenyl glycogide i8 employed in batracylin con~ugates.

H3C ~ O ~ NH2 ~ ,OH
HO
s The synthesis of peptide con~ugates of batracylin can be carried out by various methods known in peptide chemistry, which are de~cribed in a review (E. W~nsch in Houben-Weyl, volume 15 1/2 (1974)).

Because of the ri~k of racemisation, the single-step lengthening i~ carried out u~ing urethane-protected amino acids in preference to fragment condensation.

The choice of protecting groups and activation methods allows many different variations. Preferably the Wunsch-Weygand method using DCC/HOSu or, with less reactive amino functions, the acid chloride or mixed anhydride process are amployed in the condensation.

The linkage of the L-fuco~e derivatives 4 and 5 can be carried out on suitably protected peptide con~ug~te~ of batracylin by th~ method~ de~cribed.

L~ A 28 142 - 9 -.9~

Alternatively to thi~, amino acid, dicarboxylic acid or peptide conjugates of 4 and 5 can also be prepared, and subse-quently linked with batracylin or betracylin-amino acid conjugates.

Examples:

Dipeptide contugate~:

Example 1 H-D-alanyl-L-alanyl-batracylin The synthesis proceeds via 4 reaction steps ~tarting from batracylin and Fmoc-alanine and is described here as an example for Examples 1-11.

Fluorenyl-~_methoxycarbonyl-(Fmoc)-L-alanyl-_atracylin 2.5 g (8 mmol) of Fmoc-L-alanine are suspended'in 80 ml of abs. methylene chloride and treated with 870 ~1 (12 mmol) of thionyl chloride. After 30 min, the same amount of acid chloride i~ added and the mixture is ~tirred at room temperature for another hour. After concentration and subsequent distillation with CH2Cl2, an amorphous solid is obtained which iB immediately further reacted.
The Fmoc-amino acid chloride is dissolved in 80 ml of CH2Cl2 and added under a nitrogen atmosphere to a suspension of 1 g (4 mmol) of batracylin and 500 ~1 (6 mmol) of pyridine in 400 ml of abs. CH2Cl2. After stirring at room temperature for 16h, the mixture i8 Le A 28 142 - 10 -~ f~ ~ L;

concentrated and the residue which remains i8 treated in an ultrasonic bath with methanol for 30 min. After filtering off with suction and intensive washing with methanol, 2.07 g (95%~ of the target compound is S obtained, the structure of which was confirmed by NMR
spectroscopy. F~: 0.73 ~toluene/ethanol 3:1) L-Alanyl-batrac~lin 2 g (3.7 mmol) of Fmoc-alanyl-batracylin are su~pended in 50 ml of piperidine and treated in an ultrasonic bath for 30 min. The mixture i8 concentrated, subsequently distilled several times with CH2Clz and the residue i~
digested with methanol. After 10 min, the residue i8 filtered off with suction and washed until it is free of piperidine. The product is obtained in very pure form and in nearly quantitative yield.
Yield: 1.15 g (9~%). R~:0.38(CH3CN/H20/AcOH)5:1:0.2.

t-~utyloxycarbonyl-D-alanyl-L-alanyl-batracylin 340 mg (1.8 mmol) of Boc-D-alanine and 340 mg (2.7 mmol) of N-hydroxysuccinimide are dissolved in 30 ml of abs.
D~F and treated at 0C with 415 mg (2.16 mmol) of dicyclohexylcarbodiimide. After a reaction time of 2h at room temperature, 513 mg (1.5 mmol) of alanyl-batracylin are added and the mixture i8 allowed to react at room temperature for a further 16h. The ~olution is concentrated and the precipit~ted urea i8 separated off.
The crude product i8 purified by flash chromatography Le A 28 142 - 11 -'3 ~ ¢"

(eluent CH2Cl2/MeOH 99:1). The appropriate fraction3 are concentrated and the residue i5 digested with ethyl acetate to remove re~idual hydroxy~uccinimide. After concentration and drying the protected dipeptide con~u-gate i8 obtained, the structure of which i8 confirmed byNMR spectro~copy.
Yield: 570 mg (72~) Rr~0.65 (~oluene/ethanol 3:1) D-Alanyl-L-alanyl-batracyLin 570 mg (1.16 mmol~ of the protected dipeptide con~ugate Boc-D-Ala-L-Ala-batracylin are treated at O~C with 4.5 ml of anhydrous trifluoroacetic acid. Concantration, sub-sequent distillation with water and freeze-drying gives the trifluoroscetate of the target compound in quantitative yield.
Rf: 0.35(CH3CN/H20~AcOH5:1:0.2).

The following compound~ are prepared in analogy~to 1:

Example 2 H-L-Ala-L-batracylin R~:0.35(CH3CN/H20/AcOH 5sltO.2) Example 3 H-D-Ala-D-batraÇYli~
Rr 2 0.35(CH9CN/HzO/AcOH 5 t ltO.2) Le A 28 142 - 12 -Example_4 H-D-Glu~B~l-L-Ala--Rr:0.7(CH3CN/H2O/AcOH 5sls0.2) Terminal bullding blocks Boc-D-Glu(Bzl)OH

Example 5 H-Lys-Ala-batracylin Rr: O . 4 2 ( CH3CN/H20/AcOH 10: 5:3) Terminal building blocks Boc-Lys(Boc)OH

Example 6 H-Tyr-Ala-batracylin R~:0.47(CH3CN/H2O/AcOH 5:1:0.2) Terminal building blocks Boc-Tyr-OH

ExamDle 7 Z -Ly~ -Ala-batracylin R2:0.4(CH3CN/H20/AcOH 5:1:0.2) Terminal building block: Z-Ly~( Boc ) -OH

Example 8 H-Ly~ ( Boc)-Ala-batracvlin R~sO.46(CH3CN/H20/AcOH 5slsO.2) Terminal building blocks Fmoc-Ly8(Boc)~OH. ~he ~ynthe~i~

~e A 28 142 - 13 -is carried out in analogy to Example 1 wi~h the exception of the 4th step: the deblocking of the terminal amino function i8 achieved here by a ~econd Fmoc removal with piperidine, a~ ha~ been described in Example 1 for the preparation of alanyl-batracylin .

Example 9 Boc-Lys-Ala-batracylin Rf:0.42(CH3CN/H2O/AcOH 5:1:0.2) Terminal building block: Boc~Lys(Fmoc)OH
(Synthe3is as Example 8) Example 10 Fmoc-~lu-Ala-batracylin Terminal buildinq block: Fmoc-Glu(tBu)-batracylin Example 11 H-Glu-Ala-bat~acylin R~:0.24(CH3CN/HzO/AcOH 5:1:0.2) Fmoc removal from 10 Glycopeptide con~u~ate~

ExamplQ 12 R-L-Fuc-Hyac-D-Ala-~-Ala-batracylin ~-L-Fuc~A~yac-OMe Le A 28 142 - 14 -l:v ~

A mixture of 2.2 g (24.3 mmol) of methyl hydroxyacetata, 1.3 g of pulverised molecular sieve 4A and 3.8 g of mercury(II) cyanide in 50 ml of dichloromethane i8 cooled to -20C. A ~olution of peracetylated 2,3,4-tri-0-acetyl-~-L-fucopyranosyl bromide (7.0 g) in 50 ml of dichloro-methane i8 added dropwise and the mixture i8 then stirred at room temperature. The reaction i8 monitored by thin-layer chromatography (eluent: toluene/ethyl acetate 1:1 v/v R~ (1) = 0.75, Rf ( 2) = 0.61). After completion of thereaction, the mixture is diluted with dichloromethane, the precipitate is filtered off and the filtrate is washed with saturated potassium iodide ~olution and water. The organic phase is then dried over magnesium sulphate and evaporatedO The crude product is finally purified on 700 g of silica gel (Merck 7734) using toluene-ethyl acetate 5:1 (v/v) as the eluent. 3 g of product (55% of theory) are obtained as a syrupy material.

~-Fuc-Hyac-OH

~-Fuc(Ac)3Hyac-OMe i~ dissolved in 34 ml of anhydrous methanol and treated w~th 1 ml of lN sodium methoxide solution in methanol. After 4 hours at room temperature, the mixture is treated with 30.5 ~1 of an aqueous lN
sodium hydroxide solution and the hydrolysis i8 monîtored by thin-layer chromatography. (Eluent: toluene/ethanol 3sl, v/v Rs (2) ~ 0.98, R~ (3) - 0.34). After completion of the reaction, the mixture is neutralised u8ing ion exchanger SC 108 (H~, filtered and the ~iltr~te is Le A 28 142 - 15 -h concentrated. The crude product i8 finally eluted with water on an ion exchanger column containing 150 g of ion exchanger SC 108 ~H'). The product-containing fraction~
are evaporated and the pure product is obtained.
S Yield: 1.4 g (75 % of theory).

B-L-Fuc-Hyac-D-Ala-L-Ala-batra~ylin 200 mg (0.9 mmol) of ~-L Fuc-Hyac are taken up in 30 ml of DNF and treated with 208 mg (1.8 mmol) of N-hydroxy-succinimide. 223 mg (1.1 mmol) of DCC are added at 0C
and the mixture is slowly allowed to warm to room temperature. After 3h, 455 mg (0.9 mmol) of the dipeptide con~ugate from Example 1 are added. After a reaction time of 16h, the precipitated urea i8 separated off and the filtrate i8 concentrated. After digesting with methanol and reprecipitating from DMF/MeOH/isopropanol, 250 mg (47 ~) of the clean target compound are obtained:
RrsO.7(CH3CN/H~O/AcOH 5slsO.2).

The compounds 13-25 are prepared analogously by this procedure. In Examples 20-25, ~-hydroxycaprylic acid is employed instead of hydroxyacetic acid.

Example 13 B-L-Fuc-Hyac-Lys(Boc)-Ala-batracylin R~sO.43(CH3CN/H20 lOsl) Coupling building blocks H-Lys(Boc)-Ala-batracylin Le A 28 142 - 16 ~

Example 14 ~-L-Fuc-Hyac-Ly~_Ala-batxacylin Rf: 0.2(CH3CN/H2O/AcOH 5sl:1.2) (Deblocking of the compound from Example 13) Example 15 H-Lysl~-L-Fuc-Hyac~-Ala-batracylin Rf: 0.18(CH3CN/H2O/AcOH 5:1:0.2) (Coupling building block: Boc-Lys(H)-Ala-batracylin Example 16 B-L-Fuc-Hyac-Lys(B-L-Fuc-Hyac)-Ala-batracylin Rf:0.5(CH3CN/H2O 5:1:0.2) Example 17 Z-LystB-L-Fuc-Hyac)-Ala-batracylin R~:0.5(CH3CN/H20 10:1) (Coupling building block: Z-Lys(H)-Ala-batracylin) Example 18 B-L-Fuc-Hyac-Glu-Ala-batracylin R~:0.1(CH3CN/H2O 10:1) (Coupling building block: H-Glu(tBu)-Ala-batracylin;
tBu removal analogous to Boc removal in Example 1) Example 19.
B-L-Fuc-H~yac-Tyr(OH~-Ala-batracylin R~s0.78(CH3CN/H2O/AcOH 5:1:0.2) Le A 28 142 - 17 -$ ~

Exampl~ ?
Boc-Lysl~-L-Fuc-Hycapr)-Ala-batracylin Rf:0.48(CH3CN/H2O 10:1) Example 21 S H-Lys(B-L-Fuc-Hycapr~-Ala-batracylin Rf:0.45~CH3CN/H2O/AcOH lOs3s1.5) (Coupling building block: Boc-Lys-Ala-batracylin) ExamDle 22 B-L-Fuc-Hycapr-Lys-Ala-batracylin (Coupling building block: H-Lys(Boc)-Ala-batracylin) Example 23 B-L-Fuc-Hycapr-Lys(~-L-Fuc-Hycapr~-Ala-batracylin (Coupling building block: H-Lys-Ala-batracylin) Example 24 ~-L-Fuc-HycaPr-D-Ala-L-Ala-b--atracylin Example 25 B-L-Fuc-H~capr-Glu-Ala-batracylin (Coupling building block: H-Glu(tBu)-Ala-Batracylin) Example 26 B-L-Fuc-pAp-sg~c-Ala-Batracylin ~-L-Fuc-pAPs 170 mg (0.67 mmol) o ~-~p-aminophenyl)-L-fueoside are treated $n 10 ml of DMF with 67 mg (O.67 mmol) of Le A 28 142 - 18 -c~

succinic anhydride. After stirring at RT for 2h, the mixture is concentrated and the product is precipitated from isopropanol/ether.
Yield: 2no mg (85~) R~: 0.15(CH3CN:H20 lO:l) Linkage with alanyl-batracylin is carried out in the presence of DCC/HOSu as described in Example 1.
Yield: 265 mg (72%) R: 0.44(CH3CN/H20 10:1).

Examples 27 and 28 are prepared analagously to this procedure.

Example 27 ~-L-Fuc-pAP-Suc-Val-batracylin Example 28 B-L-Fuc-PAP-Glut-Ala-batracylin Example 29 B-L-Fuc-~-AHex-Suc-Ala-batracylin Glycosylation reaction in analogy to Example 12, starting from peracetylated L-fucosyl bromide and N-benzyloxy-carbonyl-~-aminohexanol, which can be prep~red in a known manner.

Le A 28 142 - 19 -3 ~

~-L-Fuc-~-AHex Deblocking as in Example 12, followed by hydrogenolytic Z-group removal.

~-L-Fuc-~-AH~x-Suc-OH
Reaction with succinic anhydride as in Example 26 ~-L-Fuc-~-AHex-Suc-Ala-batracylin Coupling reaction as described in Example 1 Examples 30 and 31 are prepared analogously.

Example 30 H-Glu(~-Fu~~ Hex~-Ala-batracylin (Coupling building block: ~oc-Glu-Ala-batracylin) Exam~le 31 H-Çlyl~-Fuc-pAP)-Leu-batracylin (Coupling building blocks Boc-Glu-Leu-batracylin) Material and methods for biological testin~

The cell line SW 480 (CCL 228) comes from a human adenocarcinoma of the colon. It was isolated by A. Leibovitz in the period from 1971-1975 and is produced by ATCC in the 96th passage.

In the experiments, it WaB employed after 104 to 111 passages. The nutrlent medium used was L 15 (Gibco) Le A 28 142 - 20 -TJ I ~ ' containing 10% foetal calf serum (L 15/FCS 10). The control cell line aHK was cultured in DMEM/FCS10 medium.
It was after 109-116 passage~.

Culture c nditions for g~owth inhibition tests SW 480 cells were raised in L15/FCS10 medium in Roux dishe~. The medium was replaced 24 hours before use and 0.1% BSA was additionally added. The culture was then trypsinised and taken up in NEME (Flow) with the addition of10%FCS andO.1%BSAto a cell count of 100,000 cells~ml.
0 100 ~1 of cell 8U pension/wellwere added to a 96 microwell plate and incubated at 37C in a CO2 incubator for 3 days.
100 ~1 of MEME medium was then added to 1 ~1 of DMSO
containing the test substances (glycocon~ugates). The growth was monitored daily.
Confluent precultures of BHR were trypsinised and taken up in GNEM (Plow) medium in 10% tryptose (Gibco), 10%
newborn calf serum, 0.5 ~ L-glutamine solution lOQ x (Gibco), 0.75 % penicillin/streptomycin solution (Gibco) and 0.1 % of ~SA to a cell count of 100,000 cells/ml.
100 ~1 of cell suspension/well were added to 96 well microtiter plates and incubated at 37C in a CO2 incubator for 24h. 100 ~1 of GMEM medium and the test substances in 1 ~1 of DNSO were then added per microwell. The growth was monitored daily.

Le A 28 142 - 21 -Growth inhibition test~

40 ~1 of MTT solution t3-[4,5-dimethyl~hiazol-2-yl]-2,5-diphenyltetrazolium bromide) having a starting concent-ration of 5 mg/ml of H20 were added to each microwell S every 24h. The mixture wa~ incubated at 37~C in the C02 incubator for 5 hours. The med~um wa~ then a~pirated and 100 ~1 of i-propanol/well were added. After shaking for 30 min, the absorption at 545 nm was measured using a Titertek Multiscan MCC/340 (Flow).

Le A 28 142 - 22 -

Claims

1. Compounds of the general formula [R]-AA1-AA2-C

where C = a cytostatic, R = , X = alkylene or arylene Y = CO, NH, O
B = a bond or diacyl radical of a dicarboxylic acid, AA1= is a natural amino acid radical in the L- or D-configuration or a bond.
and AA2= is a natural amino acid in the D- or L-configuration or a bond, n = 0, 1 or 2.

2. Compounds according to Claim 1 in which X denotes p-phenylene or (CH2)m, where m can be 1-20, Y denotes CO or NH, Le A 28 142 - 23 -B denotes a bond or a diacyl radical of a C3-C8-dicarboxlic acid, n denotes 0, 1 or 2.

3. Compounds according to Claim 1 in which AA1 denotes amino acid radicals having acidic or basic aide chains, or a bond, AA2 denotes amino acid radicals such as Ala, Val, Leu, Ile, Nva, Gly or Phe (D- or L-configuration), which are linked to the heterocycle and to AA1 in amide fashion.

4. Compounds according to Claim 1 in which C
represents , Le A 28 142 -24-

5. A compound of the general formula I
[R]-AA1-AA2-C I
wherein C represents a cytostatic radical;
R represents a group of formula , X represents an alkylene or an arylene radical;
Y represents CO, NH or O;
B represents a bond or a diacyl radical of a dicarboxylic acid;
AA1 represents a natural amino acid radical in the L- or the D-configuration or a bond;
AA2 represents a natural amino acid radical in the L- or the D-configuration or a bond; and n has the value 0, 1 or 2;
provided that if n has the value 0 then AA1 and AA2 do not both represent bonds.

6. A compound according to claim 5 wkerein C represents a cytostatic radical derived from an amino group containing cytostatic molecule by removal of a hydrogen atom from the amino group, the cytostatic molecule being batracylin, methotrescate, nimestin or daunorubicin.

7. A compound according to claim 6 wherein the cytostatic molecule is derived from batracylin.

8. A compound according to claim 5 wherein Y represents CO and B represents a bond.

9. A compound according to claim 5 wherein Y represents NH or O and B represents a diacyl radical of a dicarboxylic acid.

10. A compound according to any one of claims 5 to 9 wherein X represents a p-phenylene radical or a (CH2)m radical in which m has a value from 1 to 20, Y represents CO and B
represents a bond or Y represents NH and B represents a diacyl radical of a C3-C6 dicarboxylic acid and n has the value 0, 1 or 2.

11. A compound according to claim 10 wherein n has the value 1.

12. A compound according to any one of claims 5 to 9 and 11 wherein R represents a .beta.-L-Fuc-Hyac-, .beta.-L-Fuc-Hycapr-, .beta.-L-Fuc-pAP-Suc-, .beta.-L-Fuc-pAP-Glut-, .beta.-L-Fuc-pAP, B-L-Fuc-.omega.-AHex- or .beta.-L-Fuc-.omega.-AHex-Suc- radical.

13. A compound according to any one of claims 5 to 9 and 11 wherein AA1 represents an amino acid having an acidic or a basic side chain, or a bond, and AA1 represents an amino acid selected from the group consisting of Ala, Val, Leu, Ile, Nva, Gly and Phe (in the D- or L-configuration) linked to the cytostatic radical c via an amide linkage.

14. The compound .beta.-L-Fue-Hyac-D-Ala-L-Ala-batracylin.

15. A process for preparing a compound of formula I, as defined in claim 5, which process comprises condensing a reagent (A) with a reagent (B), wherein reagent (A) is selected from R, [R]n-AA1 and [R]n-AA1-AA2 and reagent (B) is selected from AA1-AA2-C, AA2-C and C, respectively, R, n, AA1, AA2 and C
being as defined in claim 5, the reagents (A) and (B) being protected if required and protecting groups being subsequently removed.

16. A pharmaceutical composition which comprises one or more of the compounds as claimed in any one of claims 1 to 9, 11 and 14 together with a suitable diluent or carrier.

17. A process for preparing a pharmaceutical composition, in ready-to-use drug form, for use as an anti-tumour agent, which process comprises admixing a compound as claimed in any one of claims 1 to 9, 11 and 14 with a suitable diluent or carrier.

18. A commercial package containing, as active pharma-ceutical ingredient, a compound as claimed in any one of claims 1 to 9, 11 and 14 together with instructions for the use thereof as an anti-tumour agent.

19. The use of a compound as claimed in any one of claims 1 to 9, 11 and 14 for treatment of tumours.