POLYETHYLENE GLYCOL DERIVATISED DIHYDRO OR TETRAHYDRO PORPHYRINS, THEIR PREPARATION AND THEIR USE AS TUMOUR LOCALISING, PHOTOSENSITISING COMPOUNDS

DIHYDRO OU TETRAHYDROPORPHYRINES DERIVEES DU POLYETHYLENEGLYCOL, LEUR PREPARATION ET LEUR UTILISATION EN TANT QUE COMPOSES DE PHOTOSENSIBILISATION SERVANT A LOCALISER DES TUMEURS

English Abstract

Compounds being polyethylene glycol derivatised, pharmacologically acceptable,
tumour locating dihydro or tetrahydro porphyrins of formulae (4, 5 and 6),
wherein R1n may be -OH but in at least two instances is a chain of formula (-O-
Xp-[CH2CH2O]m-Y)n wherein n = 1 to 3, m = 5 to 250 and p = 0 to 1; the group Y
may be a C1-C12 alkyl or acyl group but preferably a methyl group; the linking
group X may be present or absent, but if present may be of the following
alternative forms: R2 = -(C=O)-(CH2)q-O- where q = 1 to 5; R3 = -CH2-CH(OH)-
(CH2)s-O- where s = 1 to 4; R4 = -(C=O)-(CH2)t-(C=O)-O- where t = 1 to 4.
Improved tumour localisation of polyether-substituted photosensitising
compounds is given leading to their more efficient uptake into tumour cells.
Lower overall doses of drug give an improved side-effect profile of the
treatment especially with regard to skin photosensitisation.

French Abstract

Ces composés sont des dihydro ou tétrahydroporphorines dérivées du polyéthylèneglycol, acceptables sur le plan pharmacologique, servant à localiser des tumeurs et répondant aux formules (4), (5) et (6) dans lesquelles R?1¿¿n? peut représenter -OH mais, dans au moins deux cas, représente une chaîne de formule (-O-X¿p?-[CH¿2?CH¿2?O]¿m?-Y)¿n? dans laquelle n vaut 1 à 3, m vaut 5 à 250 et p vaut 0 à 1; le groupe Y peut représenter un groupe acyle ou alcoyle C¿1-12? mais représente, de préférence, un groupe méthyle; le groupe de liaison X peut être présent ou absent, mais s'il est présent, il peut représenter l'une des formes suivantes: R?2¿ = -(C=O)-(CH¿2?)¿q?-O- où q vaut 1 à 5, R?3¿ = -CH¿2?-CH(OH)-(CH¿2?)¿s?-O- où s vaut 1 à 4, R?4¿ = -(C=O)-(CH¿2?)¿t?-(C=O)-O- où t vaut 1 à 4. Ces composés de photosensibilisation à substitution polyéther permettent de mieux localiser les tumeurs grâce à leur pénétration plus efficace à l'intérieur des cellules tumorales. Des doses globalement inférieures de médicament permettent d'améliorer le profil d'effets secondaires du traitement, notamment en égard à la photosensibilisation de la peau.

Claims

9
CLAIMS
1. Compounds being polyethylene glycol derivatised, pharmacologically acceptable,
tumour locating dihydro or tetra-hydro porphyrins of the formulae (4), (5) and (6)
<IMG> <IMG>
(4) (5)
<IMG>
(6)
wherein R1n may be -OH but in at least two instances is a chain of formula (-O-Xp-
[CH2CH2O]m-Y)n wherein n = 1 to 3, m =; to 250 and p = 0 to 1; the group Y
may be a C1 - C12 alkyl or acyl group but preferably a methyl group; the linking group
X may be present or absent, but if present may be of the following alternative forms:-
R = - (C = O) - (CH2)q - O - where q = 1 to 5
R3 = -CH2 - CH(OH) - (CH2)5 - O - where s = 1 to 4
R4 = -(C = O) -(CH2)t - (C = O) - O - where t = 1 to 4.
2. Compounds of claim 1 as derivatives wherein one or more hydroxyl group is
otherwise derivatised; or as hydrochlorides, sulphates or other salts with mineral acids;

or as metal complexes with Zn, Ga or other metals; or as hydrates or solvates with lower
(C1-C4) alcohols.
3. Methods of using, compounds according to claim 1 or 2 to make medicaments for
therapy of tumours susceptible to necrosis when such a compound is administered to
locate in the tumour followed by irradiation of the tumour with visible light of a
wavelength absorbed by the compound, the said methods making use of the compounds
by associating them with a pharmaceutical diluent or carrier.
4. The subject matter of claims 1 and 2 or 3, wherein the molecular weight of the
compounds (4), (5) or (6) is 5,000 D to 20,000 D.

Description

218943~
.
Tl[J~IOUR LOCALlSl~rG PHOTOSENSITISlNG COMPOU~S :
This invention }elates to polyether-substituted photns~nciri~in~ compounds and
their use in the treatment of tumours.
Photodynamic therapy involves the ~iminiitr~rinn of a ph~rosf~n~iri~incr compound
followed by irradiation of the tissue containing the compound with visible light of a
specific wave~ength. The resulting activated compound, with oxygen, forms a reactive
radical which causes necrosis of the surroundin~ tissue.
The success of this modali[y is de?endent on ~rlminicrr~rion of a compound whichis selectively retained in tumo~lr tissue as compared to normal tissue and thus on
irradiation of the tumour with visib~e Light. the amount of damage caused by necrosis in
tumour tissue Is proportiollally higher than that in norlrlal tissue. However some normal
tissue damage may occur and one sp~cific side effect seen with the use of many
phoros~n~iric~rs is redness and sv~elling (~rythema) of the s'r~in on exposure to normal
lighting levels, and particularly sunlight. This requires patients to be kept in subdued
light for some weeks after treatment which can restrict their quality of life. A more
efficient delivery of the phnrnsPn~ inr~ compound into tumour tissue, thus providing a
much higher ;umour to norm Ll-skin ratio of drug concentration could dramatically reduce
the potenhal tor skin side eftects ~.vith this trea~ment.
Such tumour localisatioll can also be used as a diagno$tic tool for determination
of tumour position, size etc. and tll~ls of the treatment of choice. Certain
photosensitisers can b~ used as diagnostic tools, if applicable as sources of detectable
fluorescence. rn addition certain radio-lr~elied entities can also be incorporated into the
tumour localising compounds for th~ purpose of diagnosis.
Photosensitisin~r compoLInds ~onta.ning a p~orpllyrln ring are well 'r~no-~n -.rom the
pFlor arr. EP-ClSS~6'-~ sclose~ ~e~ri ?ll~nvlporpllyrins h Lving various substituents on
;~,r~ lr ~ nn,s. .~ furtiler group ot pllo~osensl~ising compounds hi-LYe previousiy been
thr~ subject of EP 0 3~ 601 .'~1. These compounds are dihydroporpllvrins (chlorins) (1)
AM~DE~ SH~T

~` ~189~3~ 2
and the correspondin ~etrahydro porph~rins (bacteriochlorins) (~ nd (3) ofi the
`ormulae: `
~ ?. ~ -
'~ '~
~~ : /~` '
?. , . T
i~ '~ _
'~
/\~ ,
wherein each R is a hydroxyl joroup (one or more in each rinV ie.. n = 1 to 3) and is in
an ortho meta or para position relative to the position of i attachment ot the phenyl nn~
to the nucleus.
Said substituent vroups may be in the same or dirferent positions on their
res?ec ive phenvi jorou?s and may be liree subs;i~u~ed~ or par~ sub~ uted. ror exampie
wi[h ~ A i or ac~L =roups containino I to c~ri~on i toms. The aucieus or the ?henyl
~n~s may be suosri~u-.ed turiher~ provided pna.~lnAcoiovical to~erabiiity appreciab~e
AMENDE~ S~EET
_ . . _ _ . .

4~ J IY' h
solubility in water-based pharmacologically acceptable solutions (required so that the
drug may be administered intravenously to ensure rapid distribution to the tumour),
absorption of light at the red end of the visible spectrum, and take up in cancerous tissue
are }etained. Such further substituted compounds, when derivatised as discussed beiow,
are regarded as forms of the l u~ ou~lds of the innovation and included in the scope of
the claims herein.
Any of the compounds may be in the form of their salts at acidic or basic centres,
or their metal complexes (e.g. Zn, Ga), o`r their hydrates or other solvates particularly
with lower, e.g. Cl - C4, aliphatic alcohols.
Various specific compounds within the above formulae (each phenyl group
carrying an R group) are given in Table I below:-
TABLE I
No n R
la 1 meta OH
lb 1 para OH
lc 1 ortho OH
2a 1 metaOH
The present invention cbncerns the denvatisation or partial derivatisation of thephenolic hydroxyl groups of compounds of formulae (1), (2) and (3) with polyethylene
glycols with or without a linking group, the terminal hydroxyl being etherified or
esterified with Cl-C12 alkyl or acyl groups, the methyl group being the most preferred.
This results in compounds of types (4), (5) and (6) as shown b~low:

218~ 3~u~ ' h r~
~--r~ ln ~ r~ ln
~ /\~
~_.rd '`1~ `rd N~;~
n n - ~1 <~ R ln
~--Rl ~ Rl
(.) ~ ~: (5)
~/\\~/\
~_ Nd N~
~lr ~\ R
( 6 ~ ~( r.
Wherein R' may be R but in at least two instances is a chain of formula ~- O -
~Yp - [CH2CH201m - Y)q wherein q = I to 3, m = 5 to 250 and p = O to 1. The
group Y may be a Cl - C12 alkyl or acyl group but preferably a me~hyl group. The
linking group ~ may be present or absent, but if present may be of the following
alternative forms:-
R2 = - (C = O) - (CH2)r- O - where r = 1 to 5
R3 = CH2 - CHtOH) - (CH2)s - O - where s = 1 to 4
R4 = - (C--O) - (CH2)t - (C = O) - O - where t = 1 to 4.
Desirably the chain length of the terminally substituted polye~hylene glycol chains
is such as to provide compounds of types (~), (S) and (6) of overall molecular weight of

~189~3~
5 ~ ~ g 1 ~ 3,
no less than 5,000 D and no more than 20,000 D which is the exclusion limit of the
kidneys .
In any of the above compounds, any free hydroxyl groups may be otherwise
derivatised and salts with mineral acids (ie. hydrochlorides, sulphates, etc), metal
complexes (ie. with Zn, Ga, etc), hydrates and solvateswith lower (Cl - C4) alcohols
may be formed. All such forms are included in the claims therein.
Compounds of types (4), (~) and (6) were Rl is herein before defined and p = O
may be formed by reaction of compounds of types (1), (2) and (3) where R is herein
before defined with compounds of type (7) where Rl and n are herein before defined
and p = O in the presence of an alkali metal bicarbonate in a mixture of water and a
suitable water soluble non-hydroxyllc solvent, ie. 1,4-dioxan at a temperature between 0
and 30C.
Compounds of types (4), (5) and (6) were Rl is herein before defined, p = 1 and
X = R2 may be formed by reaction of compounds of types (1), (~) and (3) where R is
herein before defined with compounds of type (8) where Rl and n are herein before
defined, p = 1, X = R2 and Z = Cl or Br in the presence of a tertiary or"anic base,
ie. pyndine and in a suitable solvent, ie. acetonitrile at a L~ Ld~uLc between 0 and
100C.
Compounds of types (4), (5) and (6) were Rl is herein before defined, p = 1 and
X = R4 may be formed by reaction of C~ ulld~ of types (1), (2) and (3) where R is
herein before defined with compounds of type (8) where Rl and n are herein before
defined, p = 1, X = R4 and Z = Cl or Br in the presence of a tertlary organic base,
ie. pyridine and in a suitable solvent, ie. acetonitrile at a l~ dLuLe between 0 and
100C.
Compounds of types (4), (S) and (6) were Rl is herein before defined, p = 1 and
X = R3 may be formed by reaction of compounds of types (1), (2) and (3) where R is
herein before defined with compounds of type (9) where Rl, n and s are herein before
defined and p = 0, in the presence of a catalytic amount of an organic tertiary base, ie.

- 218~3~
6 ~ ~0 b
triethylamine or an inorganic base, ie. sodium hydroxide at a ~t~ ULC; between 0 and
120C .
Compounds of types (7), (8) and (9) may be obtained commercially or
synthesised by known methods by those skilled in the art.
--Rl ~1 z / \ (CH2 ) 8 R n
r N
) (8, (9)
The denvatised dihydro and tetrahydro porphyrin compounds (S), (5) and (6)
have the following properties:
1. ~ncreased aqueous solubility.
'. Longer circulation time in body.
3. Increased binding to plasma proteins.
1. Increased tumour ~ m~ ion rates when compared to parent compound.
5. Decreased skin phot~sPn~ tion~
Polyethylene glycol derivatised tetra-(3-hydroxy phenyl) chlorins (4) have been
shown in various animal tumour models to haYe enhanced tumour cnn~Pn~r~ n
properties when compared with the parent drug, to an extent that is surprising when
compared with that in denvatised porphyrins such as are disclosed inter al~a in
WO91/18630 (DKZ).
Routes of Administration
By parenteral or any other suitable route.
Flld~,.,d~cu~ical Presentations
Any suitable presentation for example:-
,

2189~3~
U ~6 s 3
1. In~ectible solution in an ampoule.2. Freeze dried powder for injection.
3. Infusion solution for addition to saline or other vehicle.
Dosages are such as to give the desired chlorin/b~ Prinl hlorin ~nn~Pnrr~ion in
the tumour and are between 0.01 mg/kg up to 100 mg~kg depending on the drug.
E~AMPLE I
To a solution of 2,3-dihydro-5,10, 15,20-tetra-(3'-hydroxyphenyl) porphyrin (la)and compound (7a, [Rl has p = 0, m = 110-120, Y = CH3], 2.0g) in dioxan (50 ml)
was added an aqueous solution of sodium bicarbonate (715 mg in 50 ml water) The
mixture was stirred at room temperature under nitrogen and then allowed to stand for 15
hours. After freeze drying, the resulting brown powder was lrl:lJ"~ llr~ in water (50
ml) and passed through a 0.2 mm Fllter and then through a molecular filter (Cut off:
10,000 D). The resulting concentrated residue was diluted to 50 ml with water and
passed through the molecular filter again. Dilution and molecular filtration were
repeated four times. The residue was diluted once more and subjected to freeze drying
to give compound mixture (4a, 0 to 2 Rl = R + 4 to 2 Rl [p = 0, m = 110-120, Y
= CH3], 702 mg) as a brown semi-crystalline powder.
In a similar manner but replacing 2,3-dihydro-5,10,15,20-tetra-(3'-
hydroxyphenyl) porphyrin (la) with the appropriate amount of 2,3,12,13-tetrahydro-
5,10,15,20-tetra-(3'-hydroxyphenyl) porphyrin (2a), there was prepared compound
mixture (5a, 1 to 2 Rl = R + 4 to 2 Rl [p = 0, m = 110-120, Y = CH3]) as a
brown semi-crystalline power.
In a similar manner but replacing compound (7a) with the dl)~UlU,Ulid~t~ amount of
compound (7b, Rl has p = 0 and m = 40-50) and using a molecular filter (Cut off:

5,000 D), there was prepared compound mixture (4b, 0 to 2 Rl = R + 4 to 2 Rl ~p =
0, m = 40-g~ C--I -

Representative Drawing