Central neural tumor destruction by controlled release of a synthetic glycoside dispersed in a biodegradable polymeric matrix

Article abstract of DOI:10.1021/jm025620k

An octyl N-acetylglucosaminide derivative with a pentaerythritol chain at position 6 has been synthesized and evaluated as an inhibitor of neural tumor growth. The glycoside inhibited the growth of a neuroectodermic tumor implanted in rats and, when loade

Full text of DOI:10.1021/jm025620k

1286
J . Med. Chem. 2003, 46, 1286-1288
Sch em e 1a
Cen tr a l Neu r a l Tu m or Destr u ction by
Con tr olled Relea se of a Syn th etic
Glycosid e Disp er sed in a Biod egr a d a ble
P olym er ic Ma tr ix
Alfonso Ferna´ndez-Mayoralas,*,†
Natalia de la Figuera,†,# Mercedes Zurita,‡
J esu´s Vaquero,*,‡ Gustavo A. Abraham,§
J ulio San Roma´n,§ and Manuel Nieto-Sampedro|
Instituto de Quı´mica Orga´nica General, CSIC, J uan de la
Cierva 3, 28006 Madrid, Spain, Hospital Puerta de Hierro,
IMSALUD, San Martı´n de Porres 4, 28035 Madrid, Spain,
Instituto de Ciencia y Tecnologı´a de Polı´meros, CSIC, J uan
de la Cierva 3, 28006 Madrid, Spain, and Instituto Cajal,
CSIC, Avda. Doctor Arce 37, 28002 Madrid, Spain
Received November 25, 2002
Abstr a ct: An octyl N-acetylglucosaminide derivative with a
pentaerythritol chain at position 6 has been synthesized and
evaluated as an inhibitor of neural tumor growth. The glyco-
side inhibited the growth of a neuroectodermic tumor im-
planted in rats and, when loaded on a slow-delivery polymer
disk, caused the destruction of cultured human astroblastoma
obtained after surgical biopsy.
Treatment of central nervous system tumors is always
problematic. Despite important advances in therapeutic
oncology, the treatment of glioma has yielded only
meager increases in survival time. Moreover, drug
delivery further restricts brain tumor treatment with
chemotherapy. The investigation of new antitumoral
substances and delivery systems is, therefore, impor-
tant.
a
Reagents and conditions: (a) n-octanol, BF3‚Et2O, CH3NO2,
The presence in brain extracts of inhibitors of astro-
blast and astrocytoma division was first described by
one of us.1 The inhibitor had glycidic epitopes im-
munologically related to those of the epidermal growth
factor receptor and of blood groups A, H, or Le.2 On the
basis of these observations, we synthesized a family of
oligosaccharides with a common Lewis X-type structure
and tested their activities as inhibitors of division of
normal and transformed neural cells.3 The tetrasaccha-
ride R-D-GalNAc(1,3)-â-D-Gal(1,4)[R-L-Fuc(1,3)]-D-GlcNAc
inhibited the division of astrocytes and astrocytoma cells
in culture and caused the destruction of a malignant
glioma formed in the rat brain after transplantation of
the C6 glioma line.4 The practical synthesis of a second
generation of R-L-Fuc(1,3)-D-GlcNAc disaccharide de-
rivatives was carried out, and the compounds were
tested as inhibitors of human glioma growth.5 Disac-
charides with a pentaerythritol or L-glyceryl chain at
the C-6 position of a GlcNAc unit showed the best
inhibitory properties. We show now that octyl 2-acet-
amido-2-deoxy-6-O-[2,2-bis(hydroxymethyl)-3-hydroxy-
100 °C, 42%; (b) TrCl, 4-DMP, pyridine, 100 °C, 84%; (c) BnBr,
NaH, THF, 80 °C, 89%; (d) p-TsOH, CH2Cl2-MeOH, room temp,
95%; (e) 6, NaH, 1:9 DMF-THF, 100 °C, 98%; (f) H2, 10% Pd-C,
MeOH, room temp, quantitative; (g) 1 M H2SO4, 3:1 dioxane-
MeOH, room temp, 99%.
propyl]-R-D-glucopyranoside (NF115, 9, Scheme 1), con-
taining the pentaerythritol chain at position 6 and a
hydrophobic octyl chain at the anomeric position, in-
hibits the growth of cultured cells of a biopsy sample of
human astroblastoma and causes a progressive decrease
of volume, eventually leading to its total disappearance,
of a primitive neuroectodermal tumor implanted in rats.
Compound 9 was efficiently synthesized starting from
readily available N-acetyl-D-glucosamine (1, Scheme 1).
Reaction of 1 with n-octanol, promoted by BF3‚Et2O,
gave R-glycoside 2, which was selectively tritylated at
the HO-6 hydroxy group with high yield (84%). Benzyl-
ation on 3 followed by detritylation afforded alcohol 5
through 4. Alkylation of 5 with cyclic sulfate 6 gave
sulfate derivative 7, which was submitted to hydro-
genolysis of benzyl and benzylidene groups to give 8.
Finally, acid hydrolysis of the sulfate group in 8
furnished the target 9. This synthetic scheme allowed
the preparation of 9 on a multigram scale.
* To whom correspondence should be addressed. For A.F.-M.:
(phone) 34 91 316 40 40; (fax) 34 91 373 05 35; (e-mail) iqofm68@
iqog.csic.es. For J .V.: (e-mail) jvaqueroc@medynet.com.
† Instituto de Qu´ımica Orga´nica General, CSIC.
#
The antimitotic activity of 9 was first tested on the
human glioma line U-373 cell, measuring the incorpora-
tion of [3H]thymidine in cultures of the cells. Compound
9 inhibited the division of U-373 cells with an IC50 of
Current address: Almirall-Qu´ımica, Parc Cient´ıfic de Barcelona,
08028 Barcelona, Spain.
‡ Hospital Puerta de Hierro.
§ Instituto de Ciencia y Tecnolog´ıa de Pol´ımeros, CSIC.
| Instituto Cajal, CSIC.
10.1021/jm025620k CCC: $25.00 © 2003 American Chemical Society
Published on Web 03/18/2003

Letters
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 8 1287
F igu r e 1. Time course of tumoral growth in rats treated with
(2) 9 and (9) saline.
43 ( 14 µM. We next studied the effect of 9 on the
growth of a tumor in vivo. We used 45 male or female
Wistar rats (1 month old and weighting 125-150 g)
bearing an ENU-induced primitive neuroectodermal,6
growing in the epicranial subcutaneous space, with a
mean volume of 0.032 cm3. Animals were treated by
intratumor administration of compound 9 (4 mg/day in
0.1 cm3 of saline; experimental group, n ) 25) or 0.1
cm3 of saline (control group, n ) 20) during the following
15 days. The tumor grew very large in controls after
implantation (Figure 1), and the rats had to be sacrificed
after 8 days. Administration of 9 slowed tumor growth
and caused a progressive reduction of its volume until
it totally disappeared. A group of five rats treated with
9 was kept without further treatment for an additional
30 days. After this time, no relapse of the tumor was
observed in any case. In addition, no clinically signifi-
cant adverse reactions were attributable to compound
9.
F igu r e 2. Tumor cell biopsy cultures in the presence of (A)
unloaded and (B) 9-loaded polymer disks.
These preliminary studies indicate tolerance of cerebral
tissue to drug-loaded disks and encourages future
clinical trials of the compound. Further work toward
clinical evaluation is in progress.
The clinical treatment of brain tumors with the
glycoside requires controlled targeted delivery of the
drug. The association with synthetic polymers has
emerged as a promising method for local drug deliv-
ery.7,8 We have recently described9 the synthesis of a
polymeric matrix capable of steady release of the
glycoside for several days in a brain homogenate. The
polymer matrix is a graft copolymer of poly(ꢀ-caprolac-
tone) on poly(methyl methacrylate) (copolymer composi-
tion of 52:48), and it shows a low degradation rate,
adequate for long-term delivery. We have now tested
the effect of polymer disks loaded with compound 9 on
cultures of cells obtained by biopsy of a tumor in a
patient suffering repeated relapses after surgical resec-
tion of a brain tumor. The tumor was typified as a
malignant astroblastoma. Cells were incubated in the
presence of drug-loaded disks weighing 360 mg (com-
pound 9 was 17% of the weight) and unloaded control
disks weighing 300 mg. Four days later, a monolayer
of viable tumor cells was observed in controls, whereas
cultures treated with drug-loaded disks showed floating
aggregates of rounded nonviable cells (Figure 2). There-
fore, glycoside 9 was released from the disk and ef-
ficiently destroyed the astroblastoma cells.
Ack n ow led gm en t. We are very grateful to Prof.
Manuel Bernabe´ for his interest and helpful discussions.
Financial support from the Comunidad de Madrid
(Grant 08.1/0011/1997) and the Ministerio de Ciencia y
Tecnolog´ıa (Grant BQU2001-1503) is greatly appreci-
ated.
Su p p or tin g In for m a tion Ava ila ble: Experimental sec-
tion containing preparation of 9 and description of the in vitro
and in vivo assays. This material is available free of charge
via the Internet at http://pubs.acs.org.
Refer en ces
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We conclude that glycoside 9 in a polymer disk may
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tumors. Intracerebral implantation in pigs of drug-
loaded disks showed lack of acute clinical toxicity.9

1288 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 8
Letters
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