Note: Descriptions are shown in the official language in which they were submitted.
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STABLE ELSAMITRUCIN SALTS SUITABLE FOR PHARMACEUTICAL
FORMULATIONS
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Patent Application No.
11/424,387 filed June 15, 2006. The content of this application is
incorporated by
reference herein in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to stable elsamitrucin salts and related
synthetic methods. Specifically, the stable, solid elsamitrucin salts of the
present
invention are suitable for preparing solutions useful for parenteral
administration in
the treatment of neoplastic diseases.
BACKGROUND OF THE INVENTION
[0003] Elsamitrucin is a heterocyclic antineoplastic antibiotic isolated from
the
gram positive bacterium Actinomycete strain J907-21 as described in United
States
patent numbers (USPN) 4,518,589 and 4,572,895 which are incorporated herein by
reference for all they disclose related to the natural history, chemical
composition,
methods of preparing and bioactivity of elsamitrucin. Elsamitrucin
intercalates into
DNA at guanine-cytosine (G-C)-rich sequences and inhibits topoisomerase I and
II,
resulting in single-strand breaks and inhibition of DNA replication.
Elsamitrucin
possesses significant oncolytic activity against metastatic cancer of the
breast, colon
and rectum, non-small cell lung and ovary and in patients with relapsed or
refractory
non-Hodgkin's lymphoma.
[0004] Elsamitrucin is known chemically as benzo(h)(1)benzopyrano(5,4,3-
cde)(1)ebnzopyran-5,12-dione,l0((2-0-(2-amino-2,6-dideoxy-3-O-methyl-alpha-D-
galactopyranosyl )-6-deoxy-3-C-methyl-beta-D-galactopyranosyl )oxy)-6-hydroxy-
1-
methyl, and has the structure generally depicted in Formula I. Elsamitrucin is
also
known as 10-0-elsaminosylelsarosylchartarin, BBM 2478A, BMY-28090, SPI-28090,
BRN 5214813, elsamicin A, elsamitrucina, and elsamitrucine.
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o\
CH3 O
OH
HO
OH J\~~NHp
O
OH
Formula I
[0005] Elsamitrucin is typically administered parenterally (generally
intravenously)
to animals, including humans and is supplied as a lyophilized powder that is
reconstituted with sterile water for injection immediately prior to use. The
prior art
lyophilized elsamitrucin powder is provided as a 1:1 succinate formed in situ
by
dissolving elsamitrucin base in an organic solvent and then adding sufficient
aqueous succinic acid to form a 1:1 solution of solubilized free base to acid.
The
resulting elsamitrucin-succinic acid suspension is then adjusted to a pH of
between
3.5 and 4.5 and mixed with a bulking agent such as mannitol to enhance
stability
prior to lyophilization (see for example USPN 5,508,268). Stable elsamitrucin
salts
in powder form (crystalline or amorphous) are not presently available thus all
highly
soluble elsamitrucin pharmaceutical compositions must be prepared in situ
using the
free base.
[0006] Therefore, there is a need for stable elsamitrucin salts that can be
stored
as dried powders for extended periods without loss of biological activity.
Moreover,
there is also a need for pharmaceutical preparations comprising stable
elsamitrucin
salts that can be prepared without the use of the free base and the
corresponding
organic solvents required to solubilize the free base in situ.
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SUMMARY OF THE INVENTION
[0007] The present invention provides water soluble, solid elsamitrucin salts
useful for preparing stable parenteral solutions intended for use in anti-
neoplastic
therapeutic regimens. Additionally, methods for preparing the stable,
elsamitrucin
salts of the present invention are provided.
[0008] In one embodiment of the present invention the counter-ion of the
stable,
solid elsamitrucin salt is selected from the group consisting of, but not
limited to,
lactate, fumarate, maleate, succinate, tartrate, tosylate, methanesulfonate,
benzoate,
salicylate, hydrochloride, sulfate, phosphate, and others.
[0009] In another aspect of the present invention the stable, solid
elsamitrucin
salts may be either crystalline or amorphous.
[0010] In one aspect of the present invention, a stable, solid Elsamitrucin
tosylate
salt is provided.
[0011] In yet another embodiment of the present invention a method for
treating a
neoplatic disease includes administrating an elsamitrucin parenteral
formulation
intravenously to a human wherein the elsamitrucin parenteral formulation
includes at
least one stable solid elsamitrucin salt selected from the group consisting of
lactate,
fumarate, maleate, succinate, tartrate, tosylate, methanesulfonate, benzoate,
salicylate, hydrochloride, sulfate and phosphate.
[0012] Still another embodiment of the present invention includes a method for
treating neoplastic diseases in a human that includes providing a parenteral
formulation consisting essentially of elsamitrucin tosylate, a
pharmaceutically
acceptable carrier and optionally at least one pharmaceutically acceptable
excipient.
[0013] In one embodiment of the present invention the neoplastic disease being
treated using the elsamitrucin parenteral formulations of the present
invention is
relapsed or refractory non-Hodgkin's lymphoma.
[0014] These and other objects, advantages and features of the invention will
be
more fully understood and appreciated by reference to the written
specification.
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BRIEF DESCRIPTION OF THE FIGURES
[0015] Figure 1: Depicts Elsamitrucin tosylate re-crystallized from 1:1
mixture of
acetonitrile:water made in accordance with the teachings of the present
invention.
DEFINITION OF TERMS
[0016] Prior to setting forth the invention, it may be helpful to provide an
understanding of certain terms that will be used hereinafter.
[0017] Analogue(s): As used herein "analogue(s)" include compounds having
structural similarity to another compound. For example, the anti-viral
compound
acyclovir is a nucleoside analogue and is structurally similar to the
nucleoside
guanosine which is derived from the base guanine. Thus acyclovir mimics
guanosine (is "analogous with" biologically) and interferes with DNA synthesis
by
replacing (competing with) guanosine residues in the viral nucleic acid and
prevents
translation/transcription. Thus compounds having structural similarity to
another (a
parent compound) that mimic the biological or chemical activity of the parent
compound are analogues. There are no minimum or maximum numbers of
elemental or functional group substitutions required to qualify as an analogue
as
used herein providing the analogue is capable of mimicking, in some relevant
fashion, either identically, complementary or competitively, with the
biological or
chemical properties of the parent compound. Analogues can be, and often are,
derivatives of the parent compound (see "derivative" infra). Analogues of the
compounds disclosed herein may have equal, less or greater activity than their
parent compounds.
[0018] Derivative: As used herein a "derivative" is a compound made from
(derived from), either naturally or synthetically, a parent compound. A
derivative
may be an analogue (see "analogue" supra) and thus may possess similar
chemical
or biological activity. However, as used herein, a derivative does not
necessarily
have to mimic the activity of the parent compound. There are no minimum or
maximum numbers of elemental or functional group substitutions required to
qualify
as a derivative. As an example, the antiviral compound ganclovir is a
derivative of
acyclovir. Ganclovir has a different spectrum of anti-viral activity from that
of
acyclovir as well as different toxicological properties. Derivatives of the
compounds
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disclosed herein may have equal, less, greater or no similar activity to their
parent
compounds.
[0019] Elsamitrucin: As used herein, the term "elsamitrucin" refers to an anti-
neoplastic composition having a molecular weight of approximately 825.83 Da
and is
known chemically as benzo(h)(1)benzopyrano(5,4,3-cde)(1)ebnzopyran-5,12-
dione,10((2-0-(2-amino-2,6-dideoxy-3-O-methyl-alpha-D-galactopyranosyl)-6-
deoxy-
3-C-methyl-beta-D-galactopyranosyl)oxy)-6-hydroxy-1-methyl, and has the
structure
generally depicted in Formula I. Elsamitrucin is also known as 10-0-
elsaminosylelsarosylchartarin, BBM 2478A, BMY-28090, SPI-28090, BRN 5214813,
elsamicin A, elsamitrucina, and elsamitrucine. See USPNs 4,518,589 and
4,572,895
for methods of isolating and characterizing elsamitrucin from natural sources.
See
also Konishi M, Sugawara K, Kofu F, Nishiyama Y, Tomita K, Miyaki T, Kawaguchi
H. 1986. Elsamicins, new antitumor antibiotics related to chartreusin I.
Production,
isolation, characterization and antitumor activity. J. Antibiot. (Tokyo)
Jun;39(6):784-
91.
[0020] Pharmaceutical Formulation: As used herein the term pharmaceutical
formulation refers to a pharmaceutically acceptable preparation comprising one
or
more of the elsamitrucin salts of the present invention and at least one
pharmaceutically acceptable carrier such as, but not limited to water for
injection,
saline or phosphate buffered saline. Moreover, the pharmaceutical formulations
of
the present invention may also include stabilizers, preservatives, buffers or
additional
therapeutic agents. The pharmaceutical formulations of the present invention
may
be administered by any means known to those skilled in the art and are ideally
suited
for intravenous administration or infection into the skin, muscle or other
tissues of the
body. The pharmaceutical formulation may be intended for oral administration.
[0021] Salt: As used herein a "salt" or "salts" include any compounds that
result
from replacement of part or all of the acid hydrogen of an acid by a metal or
a group
acting like a metal: an ionic crystalline compound. In this case, the salt is
a product
of a free base and an organic acid that can exist as a stable solid and does
not
include pseudo salts, or salts made in situ, which only exist in the solution.
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[0022] Suitable salt form(s): As used herein, the term "suitable salt form(s)"
means an elsamitrucin salt prepared in stable solid state either as amorphous
or
crystalline form.
[0023] Solid or solid salt: As used herein the term solid or solid salt refers
to an
elsamitrucin salt existing in a solid state and having less than 30% residual
moisture,
preferably less than 10% residual moisture and more preferably less than 5%
residual moisture. As used herein "moisture" refers to water or an organic
solvent.
The term "solid" is also used herein to differentiate the elsamitrucin salts
of the
present invention from salts formed in situ and exist primarily in the aqueous
phase.
[0024] Stable: As used herein "stable" refers to an elsamitrucin salt or a
parenteral elsamitrucin salt-containing formulation (made by method other than
in
situ salt formation) wherein the elsamitrucin salt retains NMR data showing a
near
perfect 1:1 salt ratio (thus indicating no decomposition in the solid state)
during
drying at elevated temperatures at 75 C for nine hours or more preferably 98 C
overnight. Moreover, stable as used herein refers to elsamitrucin salt-
contained in a
parenteral formulation that retains at least 90% of its anti-neoplastic
activity as
determined by in vitro growth inhibition testing (see Example 4) for at least
24
months in the solid form and for 18 months in the liquid form at a suitable
storage
temperature.
DETAILED DESCRIPTION OF THE INVENTION
[0025] The present invention provided water soluble, solid elsamitrucin salts
useful for preparing stable pharmaceutical formulations intended for use in
anti-
neoplastic therapeutic regimens. Additionally, methods for preparing the
stable,
elsamitrucin salts have also been provided.
[0026] In one embodiment of the present invention the stable, elsamitrucin
salts
of the present invention are selected form the group consisting of, but not
limited to,
lactate, fumarate, maleate, succinate, tartrate, tosylate, methanesulfonate,
benzoate,
salicylate, hydrochloride, sulfate, phosphate, and others. The elsamitrucin
salts of
the present invention are stable solids and may be either crystalline or
amorphous.
[0027] Elsamitrucin and structurally related antibiotics bind to GC-rich
tracts in
DNA, with a clear preference for B-DNA over Z-DNA. They inhibit RNA synthesis
and cause single-strand scission of DNA via the formation of free radicals.
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Elsamitrucin can also be regarded as the most potent inhibitor of
topoisomerase II
reported so far and can inhibit the formation of several DNA-protein
complexes.
Elsamitrucin binds to the P1 and P2 promoter regions of the c-myc oncogene
inhibits
the binding of the Sp1 transcription factor, thus inhibiting transcription.
[0028] Elsamitrucin has shown activity in patients with relapsed or refractory
non-
Hodgkin's lymphoma and in vivo activity against a wide range of murine
neoplasmas
including leukemia P388, leukemia L1210, and melanoma B16 and M5076, as well
as against MX1 and HCT116 xenografts (see for example Raber MN, Newman RA,
Newman BM, Gaver RC, Schacter LP1992 Phase I trial and clinical pharmacology
of
elsamitrucin. Cancer Res. Mar 15;52(6):1406-10).
[0029] Additionally, experimental treatment of refractory/relapsed non-
Hodgkin's
lymphoma has demonstrated that elsamtrucin-associated toxicity is relatively
mild
and consisted mainly of asthenia, nausea and vomiting and did not include
myelosuppression. The activity of elsamitrucin and its lack of
myelosuppression
suggest utility in this disease especially when combined with other proven
agents.
(see Allen SL, Schacter LP, Lichtman SM, Bukowski R, Fusco D, Hensley M,
O'Dwyer P, Mittelman A, Rosenbloom B, Huybensz S. 1996. Phase II study of
elsamitrucin (BMY-28090) for the treatment of patients with
refractory/relapsed non-
Hodgkin's lymphoma. Invest. New Drugs. 14(2):213-7.
[0030] The in vitro activity of elsamitrucin was also investigated as compared
with
that of doxorubicin (DX) on two sensitive breast cancer cell lines: one
estrogen
receptor-positive (ER+, MCF7) and one estrogen receptor-negative (ER-, MDA-MB-
231) line, and on a DX-resistant subline (MCF7DX). The activity of the two
drugs
was also investigated on 19 clinical breast cancer specimens from untreated
patients. The drugs were tested at pharamcologically relevant concentrations,
as
calculated from the area under the curve for a 3 h exposure to the lethal dose
producing 10% mortality (LD10) in mice, and at 10- and 100-fold
concentrations. In
DX-sensitive lines, a greater inhibition of RNA and DNA precursor
incorporation, as
well as of cell proliferation, was caused by elsamitrucin than by DX.
Moreover, the
antiproliferative effect was 10-fold higher in the ER+ MCF7 than in the ER-
MDA-MB-
231 cell line (IC50: 0.25 versus 0.21 micrograms/ml). Elsamitrucin was cross-
resistant to DX in the MCF7DX subline. In clinical specimens, effects on DNA
precursor incorporation were more often observed for elsamitrucin than for DX
at the
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same drug concentrations. The in vitro sensitivity to elsamitrucin was more
pronounced for ER+ than for ER- tumors: minimal inhibiting concentrations of
the
drug were 0.1 and 3.5 micrograms/ml, respectively, in the two groups. These in
vitro
results would indicate a promising role for elsamitrucin in clinical
treatment, mainly of
ER+ breast cancer patients (see Silvestrini R, Sanfilippo 0, Zaffaroni N, De
Marco C,
Catania S. 1992. Activity of a chartreusin analog, elsamitrucin, on breast
cancer
cells. Anticancer Drugs. Dec; 3(6):677-81).
[0031] United States patent number 5,508,268 issued April 16, 1996 to Nassar
et
al. assigned to Bristol-Myers Squibb (hereinafter the `268 patent) discloses
parenteral formulations comprising elsamitrucin base, an organic acid, a
stabilizer
and a buffer. The elsamitrucin compositions disclosed therein were prepared
using
various organic acids including hydrochloric, L(+)-lactic, L-tartaric, D-
glucuronic,
methane-sulfonic, adipic and succinic with the succinic acid being preferred.
The
elsamitrucin compositions are prepared according to the teachings of an
Example
occurring at column 4 lines 5-30. In this example only the succinate salt is
described. Specifically, the '268 patent, in accordance with the disclosure
therein,
the elsamitrucin salt is formed in situ using an organic acid in combination
with at
least one reducing agent (preservative) and the pH adjusted to approximately
4. The
resulting solution was filtered and retained in the liquid state for stability
testing. In
other embodiments disclosed in the `268 patent the organic acid, elsamitrucin
base,
reducing agent and other suitable pharmaceutical excipients such as, but not
limited
to sugars, are admixed in solution and the resulting composition is
lyophilized.
[0032] However, the `268 patent does not disclose, discuss or teach stable
solid
elsamitrucin salts. In sharp contrast to the teachings of the `268 patent the
present
inventors have discovered methods that provide stable solid elsamitrucin salts
made
using elsamitrucin base and selected organic acids. The resulting compositions
made in accordance with the teachings of the present invention are solid, dry
or
partially dried elsamitrucin salt powders, as opposed to lyophilizates
described in the
`268 patent. Thus, the elsamitrucin salt compositions of the present invention
are
true salts in solid state, not in situ solutions containing a solubilized base
and organic
acid admixture.
[0033] The present invention offers numerous advantages over in situ formed
admixtures as described in the '268 patent. First, the elsamitrucin salts made
in
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accordance with the teachings of the present invention can be carefully
analyzed for
impurities and refined as needed to meet exceedingly high governmental
regulations. Moreover, the true salts of the present invention can be
precisely
weighed and dissolved in suitable pharmaceutical carriers such as Water for
Injection. The selected salts themselves are extremely stable when stored in
the
solid state and have extended shelf lives as do their corresponding
solubilized
solutions. Thus, parenteral solutions can be prepared using the elsamitrucin
salts of
the present invention and stored for extended periods of time.
[0034] The following Examples are provided as illustrative embodiments of the
present invention. It should be understood that the stable dried, or nearly
dried
elsamitrucin salts of the present invention are not limited by the following
examples.
The teachings of the Examples that follow can be used by pharmaceutical
chemists
of ordinary skill as guidance in making other, variations that result in the
same
compositions as disclosed here.
Examples
METHODS OF MANUFACTURING ELSAMITRUCIN SALTS
EXAMPLE 1
INITIAL PREPARATION OF THE STABLE ELSAMITRUCIN SALTS OF THE PRESENT INVENTION
[0035] Small batches of elsamitrucin salts were prepared prior to optimization
and scale up. Eight counter ions based on organic acids were selected, these
included lactic acid, maleic acid, succinic acid, L-tartaric acid, p-
toluenesulfonic (also
referred to herein as p-TSA or tosylate), , benzoic acid, salicylic acid, and
sulfuric
acids. Three solvents were selected based on previous screen methods known to
those skilled in the art of pharmaceutical chemistry, the selected solvents
included
dioxane, dimethylformamide (DMF), and acetic acid (AcOH). An additional
combination of p-TSA/MeOH was included for a total of twenty-five variations
reactions.
[0036] To each reaction vial 3.0 x 10-5 mol of elsamitrucin base was added.
The
elsamitrucin base was dissolved in 0.25 mL of DMF or AcOH at 55 C, 1.5 mL of
dioxane at 80 C, or 12 mL of MeOH at 70 C and stirred for five minutes to
ensure
dissolution. Each vial was then charged with 245-270 pL of a 0.126 M dioxane
solution of one of the organic acids listed above (see Table 1) corresponding
to 1.05
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equivalent of each of the eight acids (tartaric acid was dispensed in a 1:1
mixture of
methanol/water due to its insolubility in dioxane).
Table 1.
A- Dioxane (1.5 mL) B - DMF (0.25 mL) C- AcOH (0.25 mL) D - MeOH (12 mL)
Acid API (mg) Acid sol. API (mg) Acid sol. API (mg) Acid sol. API (mg) Acid
sol.
0.126MmL 0.126MmL 0.126MmL 0.126MmL
1 Lactic 20.25 0.260 20.01 0.255 19.13 0.245 - -
2 Maleic 19.96 0.255 21.22 0.270 20.23 0.260 - -
3 Succinic 20.42 0.260 19.18 0.245 19.12 0.245 - -
4 L-Tartaric 20.65 0.265 19.55 0.250 19.62 0.250 - -
p-TSA 19.52 0.250 19.41 0.250 19.61 0.250 21.08 0.270
6 Benzoic 19.63 0.250 21.03 0.270 19.96 0.255 - -
7 Salicylic 19.95 0.255 21.04 0.270 20.15 0.260 - -
8 Sulfuric 19.54 0.250 21.17 0.270 19.97 0.255 - -
API=elsamitrucin base.
[0037] The initial temperature was held for ten minutes and then ramped down
to
room temperature at a rate of 20 C/hour for DMF and AcOH, 30 C/hour for
dioxane
and 25 C/hour for MeOH. Solids were formed in the vials with dioxane/L-
tartaric
acid, dioxane/p-TSA, dioxane/sulfuric acid, and AcOH/sulfuric acid. Solids
were
collected by filtration and dried in vacuo at 50 C and 30 in. Hg. Vials were
solids did
not form were concentrated to dryness with a stream of nitrogen and dried in
vacuo
at 50 C and 30 in. Hg. Methanol was removed under vacuum and the resultant
residue dried under high vacuum at room temperature. All samples were analyzed
by x-ray diffraction (XRPD), differential scanning calorimetry (DSC), and
thermogravimetric analysis (TGA) to determine the crystallinity of the salts.
Crystalline solids were obtained from dioxane/sulfuric acid and from
AcOH/sulfuric
acid; semi-crystalline solids were obtained from dioxane/L-tartaric acid,
dioxane/p-
TSA, DMF/lactic acid, DMF/maleic acid, DMF/L-tartaric acid, DMF/benzoic acid,
DMF/sulfuric acid, AcOH/lactic acid, AcOH/ p-TSA, and AcOH/benzoic acid. All
other solids were found to be amorphous by XRPD.
Example 2
Optimization of Elsamitrucin Salt Preparation
[0038] Next three elsamitrucin salts made in accordance with the teaching of
Example 1 were selected for scale-up development. The salts selected were
elsamitrucin tartrate, elsamitrucin sulfate and elsamitrucin tosylate. These
were
selected because each provided crystalline or semi-crystalline solids that
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precipitated during the cooling process, which can allow better isolation and
purification (if necessary) of the salt and thus lends them more suitable for
larger
scale manufacturing techniques. However, their selection for purposed of
Example 2
should not be considered a limitation.
[0039] L-tartaric acid, sulfuric acid and p-TSA were dissolved in dioxane.
Suitable reaction containers were each charged with 1.7 x 10-4 mol of
elsamitrucin
base which was dissolved in 7.5 mL of dioxane at 80 C, and stirred for five
minutes
to ensure dissolution. Each vial was then charged with 350-380 pL of a 0.5 M
solution of the organic acid in dioxane corresponding to approximately 1.05
equivalent each of the three acids (Table 2).
Table 2.
Elsamitrucin
Exp. # (mg) Solvent Amount (mL) Acid (0.5 M) Amount (mL)
1 118 Dioxane 9.0 Sulfuric 0.38
2 113 Dioxane 7.0 p-TSA 0.36
3 108 Dioxane 7.5 L-Tartaric 0.35
[0040] The initial temperature was held for ten minutes and then ramped down
to
room temperature at a rate of 30 C/hour for dioxane. Solids were formed upon
addition of acid to the vials with dioxane/L-tartaric acid and
dioxane/sulfuric acid and
for dioxane/p-TSA precipitation occurred during the cooling process. After
filtration
the solids were dried in vacuo at 50 C and 30 inch Hg. Samples were analyzed
by
XRPD, DSC, and TGA to determine the crystallinity (Table 3), and other
physical
properties.
[0041] As Table 3 shows, all solids in Example 2 were semi-crystalline,
contained up to about 5% of the residual solvent and were pasty in constancy
due to
the high amount of solvent that was retained in the solids due to a rapid
precipitation.
[0042] In another embodiment the elsamitrucin salts of the present invention
were prepared using a slower precipitation method than described above.
Reaction
containers were charged with 7.6 x 10-5 mol of elsamitrucin base and 5 mL of
dioxane at 80 C. After the mixture was stirred for five minutes to ensure
dissolution
of the base, 400 pL of a 0.2 M aqueous solution of tartaric acid corresponding
to
1.05 equivalents was added to the dissolved elsamitrucin base. The temperature
was held at 80 C for ten minutes and then the vials were cooled to room
temperature
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at a rate of 30 C/hour. During the cooling phase precipitation occurred. The
solids
were collected by filtration and dried in vacuo at 50 C and 30 inches Hg.
Samples
were analyzed by XRPD, DSC, and TGA to determine physical properties [Table 3,
OVL-A-55(1) and OVL-A-55(2)]. The first sample [dioxane/sulfuric acid, OVL-A-
55(1)] was crystalline by XRPD, but it contained 3.6% residual solvent
according to
TGA analysis and three endothermic peaks on the DSC curve. The second sample
[dioxane/L-tartaric acid, OVL-A-55(2)] was semi-crystalline.
[0043] Next elsamitrucin salts were prepared in an aqueous environment as
follows. Reaction vials were charged with 100 mg of elsamitrucin base, 1.05
equivalents of corresponding acid (p-TSA, succinic, and L-tartaric acid were
added
as solids; sulfuric acid was dissolved in 0.5 mL of water) and water (10 mL
for p-
TSA, succinic, and L-tartaric acid, 9.5 mL for sulfuric acid). The suspensions
were
heated to 80 C with stirring for ten minutes to form a clear solution and then
ramped
down to room temperature at a rate of 30 C/hour. After stirring overnight at
room
temperature precipitates were not formed in any of the experiments. The water
was
removed under a gentle flow of nitrogen at 35 C. Precipitation was observed in
the
p-TSA experiment after the removal of one-third of the water, this solid was
filtered
and dried in vacuo at 50 C and 30 inches Hg. The filtrate was also analyzed.
The
other three vials were evaporated to dryness and dried in vacuo at 50 C and 30
inches Hg. The results showed that the solids produced were semi-crystalline
with
high amorphous content [Table 3, OVL-A-47(1), OVL-A-47(2-1), OVL-A-47(3), and
OVL-A-65].
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[0044]
Table 3
Lab Notebook Second Drying DSC Analysis TGA wt
Lot Number Salt Solvent Solvent Conditions XRPD Ramp Onset Peak loss
C/min C C ("/o)
52.5
25 C in 138.4
5.3
Free base vacuo Crystalline 10 202.2
210.2
66.7
OVL-A-45(1) Sulfuric Dioxane 50 C in Semicrys 10 139.2 1.3
vacuo 170.0(x)
191.2
63.0
OVL-A-45(3) p-TSA Dioxane 50 C in Semicrys 10 147.7 155.8 5.0
vacuo 175.0 x
184.0
90.7
OVL-A-45(4) L-Tartaric Dioxane 50 C in Semicrys 10 192.9 202.3 5.6
vacuo 198.23
240.6 249.83
OVL-A-47(1) Sulfuric Water 50 C ivacuon Semicrys 10 139.0(x)
172.0(x)
50 C in 66.0
OVL-A-47(2a) p-TSA Water vacuo Semicrys 10 182.0(x)
186.0
OVL-A-47(2b) p-TSA Water 50 C ivacuon Semicrys 10 139.0(x)
172.0(x)
50 Cin 91.0
OVL-A-47(3) L-Tartaric Water vacuo Semicrys 10 184.0
202.0
OVL-A-51(1b) Sulfuric Dioxane EtOAc 50 Cin Semicrys 10 44.6 75.0
vacuo 176.5 179.0(x)
50 C in 184.0
OVL-A-51(2b) p-TSA Dioxane EtOAc vacuo Amorphous 10 186.0(x)
189.0
0 50 OVL-A-51(1c) Sulfuric Dioxane Heptane vacuon Amorphous 10 164.4 173.0
67.0
OVL-A-51(2c) p-TSA Dioxane Heptane 50 C in Amorphous 10 159.0
vacuo 169.0(x)
182.0
50 C in 63.0
OVL-A-51(3c) L-Tartaric Dioxane Heptane Amorphous 10 162.1 187.0
vacuo 255.2 266.0
50 C in 58.7 78.0
OVL-A-55(1) Sulfuric Dioxane vacuo Crystalline 10 199.7 205.0 3.6
209.0
50 C in 75.0
OVL-A-55(2) L-Tartaric Dioxane vacuo Semicrys 10 195.9 205.0
209.0
88.0
158.8 173.0
OVL-65 Succinic Water 50 C in vacuo Semicrys 10 189.0
210.0
OVL-67 Sulfuric AcOH MeCN 50 C in Crystalline 10 261.3 278.0 0.2
vacuo
(x) - exotherm
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Example 3
Crystallization of Elsamitrucin tosylate salt using microscopy
[0043] On a microscope slide, 1-2 mg of amorphous elsamitrucin tosylate was
sprinkled with the help of a spatula and a cover-slip was placed. Drops of
solvent
were placed on the side of the cover-slip so as to allow the solvent to sip
under the
cover-slip and dissolve the drug. The drug in contact with the solvent was
stored at
room temperature and examined under microscope with 100x or 400x
magnification.
The solvents used were isopropyl alcohol, methanol, ethanol, acetonitrile,
acetone,
propylene glycol, tetrahydrofuran, dichloromethane and 1:1 mixtures of
isopropyl
alcohol, methanol, ethanol, acetonitrile, acetone with water. Needle or rod-
shaped
crystals were observed under microscope in solvents - ethanol, methanol,
propylene
glycol, isopropyl alcohol, acetone, and all the water:solvent mixtures.
Microscopic
examination of the samples indicated that the Elsamitrucin tosylate salt
became
crystalline in at least one solvent.
Example 4
Microcrystallization of MSA, p-TSA and HCI salts of Elsamitrucin
[0044] A small amount of the salt (1-2 mg) was placed on a microscope slide
and
covered with a cover-slip. Several drops of solvent were added at the edge of
the
cover-slip so that capillary action would draw the solvent between the slide
and the
cover-stip. If the material was partially dissolved, the slide was slowly
heated on a
hot-plate until most of the solid had dissolved. Each slide was cooled at room
temperature to allow slow crystallization. 1:1 mixtures of methanol, ethanol,
isopropyl alcohol and acetonitrile in water were used for the crystallization.
Each salt
in all the four different solvent systems produced crystals of elsamitrucin.
Elsamitrucin tosylate salt crystals showed birefringence under plane polarized
light
as depicted in Figure 1.
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Example 5
Scale up of re-crystallization of p-TSA salt
[0045] The recrystallization of p-TSA salt was carried out with slow
evaporation in
the Craig tube. The p-TSA salt was dissolved in 1:1 mixture of acetonitrile
and water
at elevated temperatures. After hot filtration in the Craig tube, the solvent
from the
reaction was evaporated slowly, which yielded precipitate. Under microscope,
the
crystal habit was observed to be needle-shaped. The crystals were isolated by
filtration and dried under vacuum. The material was observed to be transparent
to
XRD, which was confirmed to be crystalline by microscopy. In the differential
scanning calorimetry analysis, the material showed a melt followed by
degradation or
crystallization at 183 C and 186 C, respectively. 1 H NMR analysis showed the
sample to be 1:1 ratio of API to the counter ion (p-TSA).
[0046] The solubility of the p-TSA salt in water was checked by HPLC after
stirring the slurry at room temperature for six hours. It was found that the
solubility of
the p-TSA salt in water is 15.6 mg/mL (Table 5, lot # OVL-A-137). The
solubility of
the p-TSA salt at pH 4 (benzoate buffer) is 14.7 mg/mL (Table 5, OVL-A-143).
Table 4
Concentration
Lab of HPLC Vial
Notebook Sample Dilution Concentration Concentration
Lot Number Counts m Factor m MW Salt m/mL
OVL-A-137 1191856 9.45269E-05 200 0.018905385 825.83 15.612634
OVL-A-143 1126074 8.9459E-05 200 0.017891806 825.83 14.77559
[0047] Elsamitrucin salts made in accordance with the teachings of the present
invention were tested for stability. Two samples of the isolated p-TSA salt
(40 mg
each) were placed in a vacuum oven at 75 C for nine hours. After this
exposure,
sample #1 was taken out, the temperature was increased to 98 C and the second
sample was dried overnight. The NMR data showed a perfect 1:1 salt ratio, so
there
was no decomposition in the solid state during drying at elevated
temperatures. The
weight loss by TGA was approximately 2.5% for both samples. Karl Fischer
analysis
indicated the two lots still had water present: sample #1 had 4.0% water
content and
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#2 had 4.6%. The p-TSA salt (16 mg) of elsamitrucin was dissolved in 1.6 mL of
benzoate buffer (pH 4) and stirred at 50 C for ten days. Samples for HPLC and
MS
were taken in 3, 5, and 10 days. No evidence of the decomposition product was
found by either MS (peak at 282) or HPLC.
Example 6
Scale-up of HCI salt formation
[0048] Elsamitrucin (200 mg) was slurried in 1 mL of acetonitrile/water (1:1)
and
heated up to 75 C resulting in a very thick slurry. A 1 M HCI solution in
water (0.321
mL, 1.05 eq.) was added to the slurry to form a clear solution. The mixture
was then
slowly cooled to room temperature at a rate of 25 C/h with very gentle
stirring. After
stirring at room temperature for approximately 6 hours, the solids obtained
were
isolated by filtration and dried in vacuo at 50 C and 30 inches Hg to yield
187.5 mg
(88.86% yield) of the HCI salt. DSC and XRD analyses confirmed the crystalline
nature of the salt.
Example 7
In Vitro Growth Inhibitory Activities of Elsamitrucin and
Elsamitrucin Tosylate Salt.
[0049] The following experiment confirms that the elsamitrucin salts made in
accordance with the teachings of the present invention retain their in vitro
anti-
neoplastic activity when compared to elsamitrucin base. Elsamitrucin and
Elsamitrucin tosylate were tested in vitro using: B16F10 (murine lung), HCT
116
(human colon), HT29 (human colon) and SK-MES-1 (human non-small cell lung
carcinoma ). Cell growth inhibition was evaluated in 96-well micro-culture
plates with
a semi-automated MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide) assay.
[0050] SK-MES-1 human non-small cell lung carcinoma, B16F10 murine
melanoma cells, HCT 116 and HT29 human colon carcinomas (collectively "test
cell
cultures") were maintained in buffered RPMI 1640 supplemented with fetal calf
serum, antibiotics and other appropriate growth factors such as glutamine.
Test cells
(1,500-2,000 cells/well) were seeded in a 96-well micro culture plate with a
total
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volume of 100 pL/well. After overnight incubation in a humidified incubator at
37 C
with 5% COZ and 95% air, elsamitrucin solutions were diluted to various
concentrations with RPMI 1640, were added to each well in a 100 pL volume. The
elsamitrucin base and the elsamitrucin tosylate solutions (elsamitrucin
solutions)
were prepared and stored in a-20 C freezer. The solutions were thawed not more
than 10 times for the entire experiment.
[0051] Cell culture plates seeded with test cells and various concentrations
of
elsamitrucin solutions were placed in a humidified incubator at 37 C, with CO2
and
95% air for 5-10 days. The plates were then centrifuged briefly, and 100 pL of
the
growth medium was removed. The cell cultures were incubated with 50 pL of MTT
reagent (1 mg/ml in DulbeccoTM phosphate-buffered saline) for 4 hours at 37 C.
The
resultant purple formazan precipitate was solubilized with 200 pL of 0.04 N
HCI in
isopropanol. Absorbance was monitored at a wavelength of 595 nm, and at a
reference wavelength of 650 nm, using a TECAN GENios mocroplate reader. In
all
experiments, absorbance data was acquired for each agent at two overlapping
concentration ranges. In most cases, the study was repeated using broader
concentration ranges.
[0052] The results of each test were stored and imported into PRISM 3.03 for
graphical analysis and determination of IC50 values. All results were graphed
as a
percentage of controlled absorbance versus the drug concentration. The IC50
values
were estimated with PRISM 3.03 using nonlinear regression analysis to fit the
data
to the sigmoidal dose-response curve described by the following four-logistic
equation:
Top - Bottom
Y = + Bottom
1 + (X/IC50)n
[0053] Top is the maximal percentage of control absorbance, bottom is the
minimal percentage of control absorbance at the highest agent concentration, Y
is
the observed absorbance, X is the agent concentration, IC50 is the
concentration of
agent that inhibits cell growth by 50% compared to the control cells, and n is
the
slope of the curve. Table 4 demonstrates that elsamitrucin and elsamitrucin
tosylate
salt possess essentially the same anti-proliferative effect on the cell lines
tested.
Thus as demonstrated in Table 4, the elsamitrucin salts made in accordance
with the
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teachings of the present invention can be expected to have equivalent, or
superior in
vivo anti-neoplastic activity as therapeutic compositions made using
elsamitrucin
base alone. The elsamitrucin tosylate comprises an IC50 that is within
preferably
about 20%, more preferably about 15% and most preferably about 10% of a
similar
amount of an elsamitrucin base.
TABLE 5: In Vitro Growth Inhibitory Activities of Elsamitrucin and
Elsamitrucin p-TSA
Salt against SK-MES-1 Human Non-small Cell Lung Carcinoma. B16F10 Murine
Melanoma and HCT 116 and HT29 Human Colon Carcinoma Cells.
Cell Line Elsamitrucin Elsamitrucin p-TSA Salt
IC50 (Pm) IC50 (pm)
SK-MES-1 0.042 0.045
1316F10 0.024 0.028
HCT 116 0.074 0.079
HT29 0.095 0.105
[0054] Unless otherwise indicated, all numbers expressing quantities of
ingredients, properties such as molecular weight, reaction conditions, and so
forth
used in the specification and claims are to be understood as being modified in
all
instances by the term "about." Accordingly, unless indicated to the contrary,
the
numerical parameters set forth in the following specification and attached
claims are
approximations that may vary depending upon the desired properties sought to
be
obtained by the present invention. At the very least, and not as an attempt to
limit
the application of the doctrine of equivalents to the scope of the claims,
each
numerical parameter should at least be construed in light of the number of
reported
significant digits and by applying ordinary rounding techniques.
Notwithstanding that
the numerical ranges and parameters setting forth the broad scope of the
invention
are approximations, the numerical values set forth in the specific examples
are
reported as precisely as possible. Any numerical value, however, inherently
contains certain errors necessarily resulting from the standard deviation
found in
their respective testing measurements The terms "a" and "an" and "the" and
similar
references used in the context of describing the invention (especially in the
context
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of the following claims) are to be construed to cover both the singular and
the plural,
unless otherwise indicated herein or clearly contradicted by context.
Recitation of
ranges of values herein is merely intended to serve as a shorthand method of
referring individually to each separate value falling within the range. Unless
otherwise indicated herein, each individual value is incorporated into the
specification as if it were individually recited herein. All methods described
herein
can be performed in any suitable order unless otherwise indicated herein or
otherwise clearly contradicted by context. The use of any and all examples, or
exemplary language (e.g. "such as") provided herein is intended merely to
better
illuminate the invention and does not pose a limitation on the scope of the
invention
otherwise claimed. No language in the specification should be construed as
indicating any non-claimed element essential to the practice of the invention.
[0055] Groupings of alternative elements or embodiments of the invention
disclosed herein are not to be construed as limitations. Each group member may
be
referred to and claimed individually or in any combination with other members
of the
group or other elements found herein. It is anticipated that one or more
members of
a group may be included in, or deleted from, a group for reasons of
convenience
and/or patentability. When any such inclusion or deletion occurs, the
specification is
herein deemed to contain the group as modified thus fulfilling the written
description
of any and all Markush groups used in the appended claims.
[0056] Preferred embodiments of this invention are described herein, including
the best mode known to the inventors for carrying out the invention. Of
course,
variations on those preferred embodiments will become apparent to those of
ordinary
skill in the art upon reading the foregoing description. The inventors expect
skilled
artisans to employ such variations as appropriate, and the inventors intend
for the
invention to be practiced otherwise than specifically described herein.
Accordingly,
this invention includes all modifications and equivalents of the subject
matter recited
in the claims appended hereto as permitted by applicable law. Moreover, any
combination of the above-described elements in all possible variations thereof
is
encompassed by the invention unless otherwise indicated herein or otherwise
clearly
contradicted by context.
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[0057] Furthermore, references have been made to patents and printed
publications throughout this specification. Each of the above cited references
and
printed publications are herein individually incorporated by reference in
their entirety.
[0058] In closing, it is to be understood that the embodiments of the
invention
disclosed herein are illustrative of the principles of the present invention.
Other
modifications that may be employed are within the scope of the invention.
Thus, by
way of example, but not of limitation, alternative configurations of the
present
invention may be utilized in accordance with the teachings herein.
Accordingly, the
present invention is not limited to that precisely as shown and described.
