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Cancer Patent Abstract
New methods for the treatment of cancer are provided. Null IGF (IGF
variants with reduced receptor binding) is administered to subjects
having cancer, thereby alleviating the symptoms of the cancer.
Cancer Patent Claims
The invention claimed is:
1. A method for slowing the growth rate of a tumor, comprising:
administering an effective amount of uncomplexed null insulin-like
growth factor I (IGF-I) to a subject having cancer.
2. The method of claim 1, wherein said cancer is selected from
the group consisting of breast, prostate, colon and lung cancer.
3. The method of claim 2, wherein said cancer is breast cancer.
4. The method of claim 2, wherein said cancer is prostate cancer.
5. The method of claim 2, wherein said cancer is colon cancer.
6. The method of claim 2, wherein said cancer is lung cancer.
7. The method of claim 1, wherein the residue at position 60 of
the amino acid sequence of said null IGF-I is altered to a non-aromatic
residue.
8. The method of claim 7, wherein the residue at position 24 or
31 of said amino acid sequence of said null IGF-I is additionally
altered to a non-aromatic residue.
9. The method of claim 7, wherein said null IGF-I is additionally
altered at a position selected from the group of positions 49, 50,
51, 53, 55 and 56.
10. The method of claim 1, wherein said null IGF-I is administered
at about 0.01 to about 50 milligrams per kilogram total body weight
per day (mg/kg/day).
11. A method for slowing progression of a cancer comprising: administering
an effective amount of uncomplexed null insulin-like growth factor
I (IGF-I) to a subject having cancer, thereby slowing progression
of the cancer.
12. The method of claim 1, wherein the residue at position 60 of
the amino acid sequence of said null IGF-I is altered to a leucine
residue.
13. The method of claim 1, wherein the residue at position 24 of
the amino acid sequence of said null IGF-I is a non-aromatic residue.
14. The method of claim 13, wherein the residue at position 31
of said amino acid sequence of said null IGF-I is a non-aromatic
residue.
15. The method of claim 1, wherein the residues at positions of
24, 31 and 60 of the amino acid sequence of said null IGF-I are
altered to a non-aromatic residue.
16. The method of claim 7, wherein said cancer is breast cancer.
17. The method of claim 7, wherein said cancer is prostate cancer.
18. The method of claim 7, wherein said cancer is colon cancer.
19. The method of claim 7, wherein said cancer is lung cancer.
20. The method of claim 8, wherein said cancer is breast cancer.
21. The method of claim 8, wherein said cancer is prostate cancer.
22. The method of claim 8, wherein said cancer is colon cancer.
23. The method of claim 8, wherein said cancer is lung cancer.
24. The method of claim 13, wherein said cancer is breast cancer.
25. The method of claim 13, wherein said cancer is prostate cancer.
26. The method of claim 13, wherein said cancer is colon cancer.
27. The method of claim 13, wherein said cancer is lung cancer.
28. The method of claim 14, wherein said cancer is breast cancer.
29. The method of claim 14, wherein said cancer is prostate cancer.
30. The method of claim 14, wherein said cancer is colon cancer.
31. The method of claim 14, wherein said cancer is lung cancer.
32. The method of claim 15, wherein said cancer is breast cancer.
33. The method of claim 15, wherein said cancer is prostate cancer.
34. The method of claim 15, wherein said cancer is colon cancer.
35. The method of claim 15, wherein said cancer is lung cancer.
36. The method of claim 12, wherein said cancer is prostate cancer.
37. The method of claim 11, wherein the residue at position 60
of the amino acid sequence of said null IGF-I is altered to a non-aromatic
residue.
38. The method of claim 37, wherein said non-aromatic residue is
a leucine residue.
39. The method of claim 37 or 38, wherein said cancer is prostate
cancer.
Cancer Patent Description
TECHNICAL FIELD
The invention relates to the field of treatment of cancer, and
particularly to the use of null IGF for the treatment of cancer.
BACKGROUND ART
Growth factors are polypeptides which stimulate a wide variety
of biological responses (e.g. DNA synthesis, cell division, expression
of specific genes, etc.) in a defined population of target cells.
A variety of growth factors have been identified, including the
transforming growth factor beta family (TGF-.beta.s), epidermal
growth factor and transforming growth factor alpha (the TGF-.alpha.s),
the platelet-derived growth factors (PDGFs), the fibroblast growth
factor family (FGFs) and the insulin-like growth factor family (IGFs),
which includes IGF-I and IGF-II. Many growth factors have been implicated
in the pathogenesis of cancer.
IGF-I and IGF-II (the "IGFs")are related in amino acid
sequence and structure, with each polypeptide having a molecular
weight of approximately 7.5 kilodaltons (kDa). IGF-I mediates the
major effects of growth hormone, and is thus the primary mediator
of growth after birth. IGF-I has also been implicated in the actions
of various other growth factors, since the treatment of cells with
such growth factors leads to increased production of IGF-I. In contrast,
IGF-II is believed to have a major role in fetal growth. Both IGF-I
and IGF-II have insulin-like activities (hence their names), and
are mitogenic (stimulate cell division).
IGF-I has been found to stimulate the growth of cells from a number
of different types of cancer (Butler et al., 1998 Cancer Res. 58(14):3021-3027;
Favoni R E, et al., 1998, Br. J. Cancer 77(12): 2138-2147). Additionally,
IGF-I has additionally been found to exert anti-apoptotic effects
on a number of different cell types, including tumor cells (Giuliano
M, et al., 1998 Invest Ophthalmol. Vis. Sci. 39(8): 1300-1311; Zawada
W M, et al., 1998, Brain Res. 786(1-2): 96-103; Kelley K W, et al.,
1998, Ann. N.Y. Acad. Sci. 840: 518-524; Toms S A, et al., 1998,
J. Neurosurg. 88(5): 884-889; Xu F, et al., 1997, Br. J. Haematol.
97(2): 429-440). U.S. Pat. No. 5,681,818 claims the administration
of IGFBP-3 for the treatment of cancer.
A number of variant forms of IGF-I have been created which have
altered binding characteristics for the IGF receptors, the insulin
receptor, or IGFBP's (Cascieri et al. (1988) Biochemistry 27:3229-3233
and (1989) Jr. Biol. Chem. 264:2199-2202; Bayne et al. (1990) J.
Biol. Chem. 265:15648-15652); Baxter et al. (1992) J. Biol. Chem.
267:60-65). Additionally, International Patent Application No. WO
97/39032 discloses the use of certain variant forms of IGF-I for
the treatment of conditions where increased IGF-I activity is desired,
such as diabetes, osteoporosis, and the like. The variant forms
of IGF-I are proposed to displace IGF-I from IGFBP, resulting in
increased IGF-I activity.
Almost all IGF circulates in a non-covalently associated complex
of IGF-I, insulin-like growth factor binding protein 3 (IGFBP-3)
and a larger protein subunit termed the acid labile subunit (ALS),
such that very little free IGF-I is detectable. The ternary complex
is composed of equimolar amounts of each of the three components.
ALS has no direct IGF-binding activity and appears to bind only
to the IGF/IGFBP-3 complex (Baxter et al., J. Biol. Chem. 264(20):11843-11848,
1989), although some reports suggest that IGFBP-3 can bind to rat
ALS in the absence of IGF (Lee et al., Endocrinology 136:4982-4989,
1995). The ternary complex of IGF/IGFBP-3/ALS has a molecular weight
of approximately 150 kDa and has a substantially increased half-life
in circulation when compared to binary IGF/IGFBP-3 complex or IGF
alone (Adams et al., Prog. Growth Factor Res. 6(24):347-356; presented
October 1995, published 1996). This ternary complex is thought to
act "as a reservoir and a buffer for IGF-I and IGF-II preventing
rapid changes in the concentration of free IGF" (Blum et al
(1991), "Plasma IGFBP-3 Levels as Clinical Indicators"
in MODERN CONCEPTS OF INSULIN-LIKE GROWTH FACTORS, pp. 381-393,
E. M. Spencer, ed., Elsevier, N.Y.). While there is essentially
no excess (unbound) IGFBP-3 in circulation, a substantial excess
of free ALS does exist (Baxter, J. Clin. Endocrinol. Metab. 67:265-272,
1988).
It should be noted that, while IGFBP-3 is the most abundant of
the IGF binding proteins ("IGFBPs"), at least five other
distinct IGFBPs have been identified in various tissues and body
fluids. Although these proteins bind IGFs, they originate from separate
genes and have distinct amino acid sequences. Unlike IGFBP-3, other
circulating IGFBPs are not saturated with IGFs. IGFBP-3 and IGFBP-5
are the only known IGFBPs which can form the 150 kDa ternary complex
with IGF and ALS. The IGF and ALS binding domains of IGFBP-3 are
thought to be in the N-terminal portion of the protein, as N-terminal
fragments of the protein isolated from serum retain these binding
activities. However, some of the other IGFBPs have also been suggested
for use in combination with IGF-I as therapeutics.
In addition to its role as the major carrier protein for IGF in
serum, IGFBP-3 has been recently shown to have a number of different
activities. IGFBP-3 can bind to an as-yet unidentified molecule
on the cell surface, where it can inhibit the activity of exogenously-added
IGF-I (Karas et al., 1997, J. Biol. Chem. 272(26):16514-16520).
Although the binding of IGFBP-3 to cell surfaces can be inhibited
by heparin, the unidentified cell surface binding molecule is unlikely
to be a heparin-like cell surface glycosaminoglycan, because enzymatic
removal of heparin glycosaminoglycans has no effect on IGFBP-3 cell
surface binding (Yang et al., 1996, Endocrinology 137(10):4363-4371).
It is not clear if the cell surface binding molecule is the same
or different than the IGFBP-3 receptor that was identified by Leal
et al. (1997, J. Biol. Chem. 272(33):20572-20576), which is identical
to the type V transforming growth factor-beta (TGF-.beta.) receptor.
IGFBP-3 has also been found to promote apoptosis. Interestingly,
IGFBP-3 has been shown to promote apoptosis in cells with and without
functional type 1 IGF receptors (Nickerson et al., 1997, Biochem.
Biophys. Res. Comm. 237(3):690-693; Rajah et al., 1997, J. Biol.
Chem. 272(18):12181-12188). However, there are conflicting reports
as to whether apoptosis is induced by full length IGFBP-3 or a proteolytic
fragment of IGFBP-3 (Rajah et al., ibid; Zadeh et al., 1997, Endocrinology
138(7):3069-3072).
IGF-I and IGFBP-3 may be purified from natural sources or produced
by recombinant means. For instance, purification of IGF-I from human
serum is well known in the art (Rinderknecht et al. (1976) Proc.
Natl. Acad. Sci. USA 73:2365-2369). Production of IGF-I by recombinant
processes is shown in EP 0 128 733, published in December of 1984.
IGFBP-3 may be purified from natural sources using a process such
as that shown in Baxter et al. (1986, Biochem. Biophys. Res. Comm.
139:1256-1261). Alternatively, IGFBP-3 may be synthesized by recombinantly
as discussed in Sommer et al., pp. 715-728, MODERN CONCEPTS OF INSULIN-LIKE
GROWTH FACTORS (E. M. Spencer, ed., Elsevier, N.Y., 1991). Recombinant
IGFBP-3 binds IGF-I in a 1:1 molar ratio.
Topical administration of IGF-I/IGFBP-3 complex to rat and pig
wounds is significantly more effective than administration of IGF-I
alone (Id.). Subcutaneous administration of IGF-I/IGFBP-3 complex
to hypophysectomized, ovariectomized, and normal rats, as well as
intravenous administration to cynomolgus monkeys, "substantially
prevents the hypoglycemic effects" of IGF-I administered alone
(Id.).
The use of IGF/IGFBP-3 complex has been suggested for the treatment
of a wide variety of disorders (see, for example, U.S. Pat. Nos.
5,187,151, 5,527,776, 5,407,913, 5,643,867, 5,681,818 and 5,723,441,
as well as International Patent Applications Nos. WO 95/03817, WO
95/13823, and WO 96/02565. IGF-I/IGOFBP-3 complex is also under
development by Celtrix Pharmaceuticals, Inc., as a treatment for
several indications, including recovery from burns and recovery
from hip fracture surgery.
While there are a large number of cytotoxic drugs available for
the treatment cancer, these drugs are generally associated with
a variety of serious side effects, including alopecia, leukopenia,
mucositis. Accordingly, there is a need in the art for cancer therapies
that do not induce the serious side effects associated with conventional
cytotoxic chemotherapy.
DISCLOSURE OF THE INVENTION
The inventor has surprisingly found that null IGF-I, administered
in the absence of IGFBP-3, is effective in alleviating the symptoms
of cancer, whereas null IGF-I administered as a complex with IGFBP-3
is ineffective. This finding was unexpected because IGFBP-3 is known
to substantially increase the half-life of IGF-I and to increase
the efficacy of IGF-I (Sommer et al., supra), so it was expected
that null IGF-I/IGFBP-3 complex would be more efficacious in alleviating
the symptoms of cancer than null IGF-I administered in the absence
of IGFBP-3.
Disclosed herein are methods for alleviating the symptoms of cancer.
In one embodiment, an effective amount of null IGF is administered
to a subject having cancer, thereby alleviating the symptoms of
the cancer.
In another embodiment, a thyroid axis antagonist is administered
with the null IGF-I to the subject having cancer.
DEFINITIONS
As used herein, the term "null IGF-I" refers to IGF-I
which has amino acid sequence alterations at one or more sites in
the molecule. Null IGF-I retains its ability to bind IGFBP-3, but
is altered in its receptor binding and/or activating properties
(e.g., having little or no binding to the type 1 IGF receptor while
maintaining its binding activities for the type 2 IGF receptor and
the insulin receptor). A preferred null IGF-I has substantially
reduced binding to both types of the IGF receptor and the insulin
receptor. Descriptions of null IGF-I's may be found in Cascieri
et al. (1988) Biochemistry 27:3229-3233; (1989) J. Biol. Chem. 264:2199-2202),
Bayne et al. (1990) J. Biol. Chem. 265:15648-15652) and Baxter et
al. (1992) J. Biol. Chem. 267:60-65). Examples of null IGF-I include
variants in which one or more of IGF-I's tyrosine residues (i.e.,
residues 24, 31, or 60) are replaced with non-aromatic residues
(i.e., other than tyrosine, phenylalanine or tryptophan), variants
where amino acid residues 49, 50, 51, 53, 55 and 56 are altered
(for example, where residues 49-50 are altered to Thr-Ser-Ile or
where residues 55-56 are altered to Tyr-Gln), and combinations thereof.
The term "thyroid axis antagonist" refers to a compound
which acts to decrease thyroid hormone activity in a subject. Thyroid
axis antagonists include 6-n-propyl-2-thiouracil (propylthiouracil
or PTU), methimazole, carbimazole, and other compounds known to
the art to reduce thyrotropic hormones, thyroid hormones, or thyroid
receptor signaling.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the amino acid sequence (SEQ ID NO: 1) of native human
IGF-I in single-letter amino acid code.
FIG. 2 depicts the results of the experiment described in Example
2. The percentage of surviving animals (y-axis) is plotted against
time after xenograft implantation (x-axis). The data for null.sub.60
IGF-I, null.sub.60 complex and control treated groups are represented
by open circles, open diamonds and open squares, respectively.
BEST MODE FOR CARRYING OUT THE INVENTION
Disclosed herein are new methods for the treatment of cancer. An
effective amount of null IGF-I is administered to a subject suffering
from cancer, thereby alleviating the symptoms of the cancer. Null
IGF-I slows the growth rate of cancer, thereby alleviating the symptoms
of, or slowing the progression of the cancer. While not wishing
to be bound by any particular theory, the inventor believes that
the administration of null IGF-I displaces native IGF-I from complexes
with binding proteins, particularly binding proteins other than
IGFBP-3 (e.g., IGFBP-2), resulting in reduced IGF-I activity, which
reduces growth of the tumor and renders the tumor cells more responsive
to apoptotic signals.
The inventors have surprisingly found that administration of null
IGF-I is substantially more effective at slowing tumor growth than
the administration of null IGF-I as a complex with IGFBP-3. This
was surprising because it is well known that uncomplexed IGF-I has
a significantly shorter half-life than IGF-I administered as a complex
with IGFBP-3 and that IGF-I administered as a complex with IGFBP-3
is more effective than uncomplexed IGF-I.
Null IGF-I may be used to treat any cancer, preferably carcinomas
such as breast, prostate, cancer and lung cancers.
Null IGF-I for use in accordance with the instant inventive methods
may be derived from any species, although species-matched null IGF-I
(i.e., null IGF-I based on the native sequence from the same species
as the subject to which the IGF-I is to be administered) is preferred.
Null IGF-I for use in the instant invention is uncomplexed null
IGF-I, that is, administered in the absence of IGFBP-3 (i.e., is
not administered as null IGF-I/IGFBP-3 complex), and is preferably
administered in the absence of any IGF binding protein.
The null IGF-I is normally produced by recombinant methods, which
allow the production of all possible variants in IGF-I sequence.
Techniques for the manipulation of recombinant DNA are well known
in the art, as are techniques for recombinant production of proteins
(see, for example, in Sambrook et al., MOLECULAR CLONING: A LABORATORY
MANUAL, Vols. 1-3 (Cold Spring Harbor Laboratory Press, 2 ed., (1989);
or F. Ausubel et al., CURRENT PROTOCOLS IN MOLECULAR BIOLOGY (Green
Publishing and Wiley-Interscience: New York, 1987) and periodic
updates).
Preferably, the null IGF-I is produced using a bacterial cell strain
as the recombinant host cell. An expression construct (i.e., a DNA
sequence comprising a sequence encoding the desired null IGF-I operably
linked to the necessary DNA sequences for proper expression in the
host cell, such as a promoter and/or enhancer elements at the 5'
end of the construct and terminator elements in the 3' end of the
construct) is introduced into the host cell. The DNA sequence encoding
the null IGF may optionally linked to a sequence coding another
protein (a "fusion partner"), to form a fusion protein.
Preferably, the DNA sequence encoding the null IGF-I is linked to
a sequence encoding a fusion partner as described in International
Patent Application No. WO 94/04076. The expression construct may
be an extrachromosomal construct, such as a plasmid or cosmid, or
it may be integrated into the chromosome of the host cell, for example
as described in International Patent Application No. WO 96/40722.
Null IGF-I is preferably administered by parenteral administration,
including but not limited to intravenous (IV), intraperitoneal (IP),
intramuscular (IM), subcutaneous (SC), intradermal (ID), transdermal,
inhaled, and intranasal routes. IV, IP, IM, and ID administration
may be by bolus or infusion administration. For SC administration,
administration may be by bolus, infusion, or by implantable device,
such as an implantable minipump (e.g., osmotic or mechanical minipump)
or slow release implant. The null IGF-I may also be delivered in
a slow release formulation adapted for IV, IP, IM, ID or SC administration.
Inhaled null IGF-I is preferably delivered in discrete doses (e.g.,
via a metered dose inhaler adapted for protein delivery). Administration
of null IGF-I via the transdermal route may be continuous or pulsatile.
For parenteral administration, compositions of null IGF-I may be
in dry powder, semi-solid or liquid formulations. For parenteral
administration by routes other than inhalation, the null IGF-I is
preferably administered in a liquid formulation. Null IGF-I formulations
may contain additional components such as salts, buffers, bulking
agents, osmolytes, antioxidants, detergents, surfactants, and other
pharmaceutical excipients as are known in the art.
Null IGF-I is administered to subjects having cancer at a dose
of about 0.01 to about 50 mg/kg/day, more preferably about 0.1 to
about 20 mg/kg/day, more preferably 0.5 to about 15 mg/kg/day, even
more preferably about 1 to about 10 mg/kg/day.
In certain embodiments, the null IGF-I is administered to the subject
with a thyroid axis antagonist. The administration of the two compounds
may be simultaneous, overlapping, or separated in time, as long
as the subject experiences exposure to both compounds at the same
time. Where the two compounds are formulated for the same route
and schedule of administration, the administration is preferably
simultaneous or nearly simultaneous (e.g., concurrent or serial
injections). However, in some embodiments, the routes and schedules
of administration for the two compounds will be different, making
simultaneous administration inconvenient. A subject will be considered
to have been administered null IGF-I and a thyroid axis antagonist
if the subject experiences simultaneous systemic exposure to both
compounds, regardless of when or how the compounds were administered.
In methods requiring the administration of thyroid axis antagonists
with the null IGF-I, the dose of the thyroid axis antagonist is
normally titrated for the individual subject, as is well known in
the art. Induction of frank hypothyroidism is not required, though
in some cases it may be found advantageous, for the proper working
of this invention. Thyroid axis antagonists are generally administered
at an intermediate dose, and the patient observed for the onset
of hypothyroidism. Hypothyroidism may be recognized by its well
known symptoms, including (in adults) lethargy, constipation, cold
intolerance, menorrhagia (in women of reproductive age), reduced
intellectual and motor activity, dry hair, dry skin, muscle aches,
reduced auditory acuity, and deepening and hoarsening of the voice.
In extreme cases, florid myxedema may be present, as indicated by
a dull, expressionless face, sparse hair, periorbital puffiness,
enlarged tongue and pale, cool skin which feels rough and doughy.
The thyroid antagonist dose should be reduced if florid myxedema
appears, to avoid the possibility of myxedema coma, a serious and
frequently fatal condition. Upon the appearance of the signs of
hypothyroidism which fall short of florid myxedema, the dose of
the thyroid axis antagonist may be reduced to the point at which
the symptoms of hypothyroidism resolve, as will be understood by
one of skill in the art.
Thyroid axis antagonists may be produced in any formulation known
to the art, including parenteral and oral dosage forms. Oral formulations
are preferred, but parenteral formulations are also acceptable,
and may be more convenient in an in-patient setting. Formulations
for parenteral administration are generally formulated as liquids,
but may also be in gel or solid depot form. Formulations for oral
administration are generally in tablet or capsule form, although
syrups and liquids are also acceptable. Formulations of thyroid
axis antagonists generally include excipients, such as salts, buffers,
bulking agents, detergents, binding agents, surfactants, stabilizers,
preservatives, anti-oxidants, lubricants, coating agents, and other
pharmaceutically acceptable excipients as are known in the art.
The dosage of thyroid axis antagonist should be adjusted according
to the identity, formulation and route of administration of the
thyroid axis antagonist which is administered with the null IGF-I,
as is known in the art. Where the thyroid axis antagonist is propylthiouracil,
the dose of propylthiouracil may be from 1 to 400 mg/day. A subject
is normally initiated with a dose of 50 to 400 mg/day, typically
divided into three equal doses, and maintained at 50 to 100 mg/day
divided into two or three equal doses. For methimazole and carbimazole,
the dose may be from 0.1 to 50 mg/day. Typically, a subject is initiated
with 5 to 50 mg/day, and maintained on 1 to 5 mg/day.
The patents, patent applications, and publications cited throughout
the disclosure are incorporated herein by reference in their entirety.
EXAMPLES
Example 1
Pharmacokinetics of Null IGF-I
The pharmacokinetics of three test articles were assayed: (1) a
recombinant human null IGF-I (Y60L IGF-I), in which the normal tyrosine
residue at position 60 had been substituted with leucine; variant
recombinant human IGFBP-3 (N109D,N172D IGFBP-3), in which the asparagine
residues normally at positions 109 and 172 were substituted with
aspartate; and Y60L IGF-I/N109D,N172D IGFBP-3 complex at a 1:1 molar
ratio. Nine mice, each weighing approximately 20-25 grams were utilized
in the study. Mouse were housed in standard mouse cages, one per
cage, and fed with water and mouse chow ad libitum.
Y60L IGF-I, N109D,N172D IGFBP-3, and Y60L IGF-I/N109D,N172D IGFBP-3
complex were dissolved in 50 mM sodium acetate, pH 5.5, 108 mM NaCl,
at 2, 8, and 10 mg/ml, respectively. The animals were randomly divided
into three groups of three animals each.
The animals received 100 .mu.l of the undiluted appropriate test
article in a single subcutaneous bolus. Blood samples (approximately
50 .mu.l each) were collected by eye-bleeds at 0.08, 1, 2, 4, and
8 house after the injection. Serum was isolated from each sample,
and assayed for human IGF-I and IGFBP-3, as appropriate, using commercially-available
immunoassay kits obtained from DSL (Webster, Tex.) according to
the manufacturer's instructions. The approximate area under the
curve (AUC) was calculated by multiplying concentrations by the
time periods between samples for each animal, and mean AUC's (in
arbitrary units) were determined for each group. The results are
shown in Table I ("nd" indicates that the assay was not
performed).
TABLE-US-00001 TABLE I Test Article Dose (mg/kg) AUC.sub.IGF-I
AUC.sub.IGFBP-3 Y60L IGF-I 10 2,597 nd N109D/N172D IGFBP-3 40 nd
15,480 Y60L IGF-I/N109D, N172D 50 7,505 37,797 IGFBP-3 complex
The data clearly indicates that, as expected, administration of
null IGF-I as a complex with IGFBP-3 substantially increases systemic
exposure to null IGF-I, as indicated by the substantial increase
in AUG.
Example 2
Treatment of Prostate Cancer Tumors with Null IGF41
Y60L IGF-I and Y60L IGF-I/N109D,N172D IGFBP-3 complex were tested
for anti-tumor activity in nude mice. 36 mice which had been implanted
with PC-3 (human prostate) tumor xenografts were obtained from the
Goodwin Cancer Institute (Plantation, Fla.). Each mouse had received
a subcutaneous xenograft of approximately 4-6 mm.sup.3 solid PC-3
tumor.
Three different test articles were employed in this experiment:
2 mg/kg/day Y60L IGF-I ("null.sub.60 IGF-I") dissolved
in 50 mM sodium acetate, pH 5.5, 108 mM sodium chloride ("vehicle");
10 mg/kg/day Y60L IGF-II/N109D,N172D IGFBP-3 complex ("null.sub.60
IGF-I complex") dissolved in vehicle; and vehicle alone ("control").
The test articles were administered near the xenograft site twice
each weekday (Monday through Friday) and once per weekend day (Saturday
and Sunday) by subcutaneous bolus injection. Test articles were
administered from day 15 after implantation ("Day 15")
until the animal was sacrificed.
Animals were sacrificed at day 57 after implantation ("Day
57") or earlier if tumor volume exceeded 2000 mm3. Tumor growth
was measured three times per week using calipers. Statistical analysis
was performed using a two-tailed t test.
Any animal that did not show evidence of tumor growth by Day 23
was eliminated from the study. 12 null.sub.60 IGF-1,9 null.sub.6O
IGF-I complex, and 11 control treated mice remained in the study
after Day 23.
Results of this experiment are depicted graphically in FIG. 2.
Survival of the control and null.sub.60 complex animals were very
similar (average survival 30.6 days and 31.1 days, respectively,
p=0.795). However, mice treated with nu160 IGF-I had substantially
greater survival, with an average survival of 35.25 days at the
end of the study (p=0.067 compared with control). It should be noted
that the average survival of the null.sub.60 IGF-I treated mice
was underestimated by this experiment, as two null.sub.60 IGF-I
treated mice had tumors of less than 2000 mm3 at the end of the
study. Inspection of FIG. 2 also reveals that median survival was
substantially increased for mice receiving null.sub.60 IGF-I.
The present invention has been detailed both by direct description
and by example. Equivalents and modifications of the present invention
will be apparent to those skilled in the art, and are encompassed
within the scope of the invention.
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