WO1998035696A1

WO1998035696A1 - Use of thymosin alpha 1 for the manufacture of a medicament for promoting stem cell development

Info

Publication number: WO1998035696A1
Application number: PCT/US1998/002830
Authority: WO
Inventors: Alan P. Knutsen
Original assignee: Sciclone Pharmaceuticals, Inc.
Priority date: 1997-02-18
Filing date: 1998-02-17
Publication date: 1998-08-20
Also published as: AU6164898A

Abstract

A method of promoting stem cell development in a mammal in need of stem cell development includes administering to the mammal a stem cell development enhancing effective amount of Thymosin α1 (Tα1).

Description

USE OF THYMOSIN ALPHA 1 FOR THE MANUFACTURE OF A MEDICAMENT FOR PROMOTING STEM CELL DEVELOPMENT

Field of the Invention

The present invention relates generally to a 5 method of promoting stem cell development.

Background of the Invention

Both B lymphocytes ("B cells") and T lymphocytes ("T cells") play important roles in mammalian immune systems . B cells control humoral immunity through 10 antibody production. T cells account for nearly all forms of cellular immunity.

T cells originate in the thymus . Generally, thy ic ste cells which are derived from precursor cells originating in bone marrow develop into blast

15 cells which, in turn, develop into a variety of mature T cells . The developmental process from stem cell to mature T cell is referred to as stem cell differentiation or thymopoiesiε . The developmental process from bone marrow precursor cell to mature T

20 cell is referred to as T cell development. Stem cell development may include stem cell proliferation and differentiation into T cells. If stem cell differentiation progresses slowly or incompletely or if there is a shortage of stem cells in the thymus, a

25 deficiency of T cells can result. Thus, a T cell deficiency can result from a number of different factors. For example, T cell deficiencies exist in immunodeficient humans, such as individuals infected with HIV. In humans infected with HIV, it is believed that such deficiencies result not only from the virus attacking and killing T cells (e.g., CD4 cells) but also from a decrease in stem cell differentiation in the infected humans due to a change in the thymic milieu caused by the overall HIV infection. Moreover, T cell deficiencies exist in humans having a shortage of stem cells, such as individuals in need of a bone marrow transplant .

Thymosin Fraction Five (TF-5) , originally described by Goldstein et al . (Proc. Nat ' 1 Acad. Sci . (USA) . 69:1800-1803 (1972)), is a partially purified extract of bovine thymus containing at least 40 peptide components, 20 of which have been purified to homogeneity or near homogeneity; it contains about 0.6% of Thymosin o _ (To_) . Low, T.L.K., et al . , "Thymosins: Structure, Function and Therapeutic Application", ymus , 6:27-42 (1984) .

Thymosin ._ ("Tα_") is a peptide originally derived from the thymus gland, which has been reported as containing 28 amino acids. Amino acid sequence information on T _x is disclosed in U.S. Patent No. 4,079,127.

Tα_ is an immune system modulator which heretofore has been reported as being useful, inter alia, in the treatment of lung cancer, Hepatitis B and Hepatitis C. Moreover, it previously has been suggested that Tct_ might induce the expression of certain T cell markers as well as functional activity associated with lymphocyte maturation such as helper T cell activity, specific antidody production and production of macrophage inhibiting factor. Low, 1984, supra . at page 33.

A T cell deficiency as described above can have devastating and sometimes fatal effects on those afflicted with this condition, as is evident from recent experience with AIDS. Clearly, there is a need in the art for new and effective methods of promoting development in humans who are T cell deficient. Accordingly, there is a need in the art for new and effective methods of promoting stem cell development in those individuals in need of such development.

Summary of the Invention

In accordance with the present invention, a method of promoting stem development in a mammal in need of stem cell development includes administering to said mammal a stem cell development enhancing effective amount of Thymosin ot_ .

Also in accordance with the present invention, a method of promoting T cell differentiation from stem cells in a mammal in need of T cell differentiation includes administering to said mammal a T cell differentiation effective amount of Thymosin α₁.

Brief Description of the Drawings

Fig. 1 is a schematic diagram depicting the in vi tro coculture model of thymopoiesis utilized in Example 3.

Fig. 2 is a graph depicting the results of purifying CD34+ stem cells from bone marrow. These results show that >99% of the stem cells utilized in the in vi tro coculture model of thymopoiesis expressed CD34+.

Fig. 3 depicts flow cytometry results which show the effect which To^ had on the cell number per well as a function of time in the in vitro stem cell-cultured thymic epithelial fragment (SC-CTEF) coculture model of thymopoiesis illustrated in Fig. 1.

Fig. 4 depicts flow cytometry results which show the effect Ta_ had on the expression of CD25+ as a function of time in the in vi tro SC-CTEF coculture model of thymopoiesis illustrated in Fig. 1.

Fig. 5 depicts flow cytometry results which show the effect Tα_: had on the expression of CD44+25+ as a function of time in the in vi tro SC-CTEF coculture model of thymopoiesis illustrated in Fig. 1.

Fig. 6 depicts flow cytometry results which show the effect Tα_: had on the expression of CD44+25+3- as a function of time in the in vi tro SC-CTEF coculture model of thymopoiesis illustrated in Fig. 1. Fig. 7 depicts flow cytometry results which show the effect To^ had on the expression of single positive CD4+ (spCD4+) as a function of time in the in vi tro coculture model of thymopoiesis illustrated in Fig. 1.

Description of the Preferred Embodiments

It surprisingly has been discovered that Thymosin _: (Tα_:) is particularly and unexpectedly effective in promoting stem cell development. This is particularly advatageous for mammals in need of such development. The terms "Thymosin ay and "TcV refer to peptides having the amino acid sequence disclosed in U.S. Patent No. 4,079,127, the disclosure of which is incorporated herein by reference. According to the present invention, methods of promoting stem cell development and T cell differentation from stem cells are provided. The methods of the present invention include administering to the mammal a stem cell development enhancing effective amount of T _! .

According to preferred embodiments of the present invention, effective amounts of Tα_: are administered to mammals in need of stem cell development to promote stem cell development in the mammals. The amount of Tα_x administered to the mammals to promote stem cell development is preferably between about 0.1 μg Ta_l per kg body weight of the mammal and about 4 μg Tα_x- per kg body weight and, more preferably, between about 5 μg Tα_x per kg body weight (i.e., about 0.5 mg Ta_ ) and about 65 μg Toc₁ per kg body weight (i.e., about 5 mg Tα_:) . In a most preferred embodiment of this invention, about 20 μg Tot]_, per kg body weight (i.e., about 1.6 mg_Tα₁) is administered to the mammals in need of stem cell development. Actual dosages administered can be in the range of about 0.1-10 mg, about 0.5 - 5 mg or about 1-2 mg, with a dosage of 1.6 mg being contemplated. In these embodiments, the mammals preferably are human.

According to one aspect of the present invention, the mammals to which Tα_x is administered are in need of stem cell development. Mammals in need of stem cell development may include, but are not limited to, mammals that are T cell- and/or stem cell-deficient. Ta₁ may also promote stem cell proliferation. Mammals afflicted with an immunodeficiency disease (e.g., humans who have AIDS or are HIV positive) and animals in need of a bone marrow transplant are generally in need of stem development. According to another aspect of the present invention, T j can be administered to mammals in need of stem cell development on a routine basis. For example, Tα_x can be administered daily, twice a day, three times a day, every other day, weekly, monthly, etc. The frequency of administration, of course, will depend upon the quantity and formulation of Ta_ being administered.

According to the preferred embodiments of the present invention, compositions containing Tcx_ may be formulated in a conventional manner for administration by any suitable route. Suitable routes of administration include, but are not limited to, oral, rectal, nasal, topical, vaginal, and parenteral (including subcutaneous, intramuscular, intravenous and intradermal) . Particularly preferred embodiments utilize oral or parenteral administration, with parenteral administration being a more preferred embodiment. It will be appreciated that the preferred route may vary with the condition, age and species of the recipient.

While not essential, in preferred embodiments, Ta_ is administered as part of a pharmaceutical formulation. The formulations of the present invention comprise Tα_x together with one or more pharmaceutically acceptable carriers and optionally with other therapeutic ingredients. The carrier (s) are "acceptable" in the sense of being compatible with the other ingredients of the formulation and not deleterious to the recipient thereof.

The formulations include those suitable for oral, rectal, nasal, topical (including buccal and sublingual) , vaginal or parenteral (including subcutaneous, intramuscular, intravenous and intradermal) administration. The formulations may conveniently be presented in unit dosage form, e.g., tablets and sustained release capsules, and may be prepared by any suitable pharmaceutical methods.

Such methods include, but are not limited to, the step of bringing into association Tα_x with the carrier which constitutes one or more accessory ingredients. In general, the formulations are prepared by uniformly and intimately bringing into association Tα_x with liquid carriers or finely divided solid carriers or both, and then, if necessary, shaping the product.

Formulations of the present invention suitable for oral administration may be presented as discrete units such as capsules, cachets or tablets each containing a predetermined amount of To^; as a powder or granules; as a solution or a suspension in an aqueous liquid or a non-aqueous liquid; or as an oil-in-water liquid emulsion or a water-in-oil liquid emulsion, etc. A tablet may be made by compression or molding, optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing in a suitable machine Tot_ in a free-flowing form such as a powder or granules, optionally mixed with a binder, lubricant, inert diluent, preservative, surface-active or dispersing agent. Molded tablets may be made by molding in a suitable machine a mixture of the powdered compound moistened with an inert liquid diluent. The tablets may optionally be coated or scored and may be formulated so as to provide slow or controlled release of the active ingredient therein.

Formulations suitable for topical administration include lozenges comprising Υ x_ in a flavored basis, usually sucrose and acacia or tragacanth; pastilles comprising Ta_ in an inert basis such as gelatin and glycerin, or sucrose and acacia; and mouthwashes comprising Tu_ to be administered in a suitable liquid carrier. Formulations suitable for topical administration to the skin may be presented as ointments, creams, gels and pastes comprising Tα_x and a pharmaceutically acceptable carrier, or may utilize a transdermal patch containing the ingredient to be administered. Formulations for rectal administration may be presented as a suppository with a suitable base comprising, for example, cocoa butter or a salicylate.

Formulations suitable for nasal administration wherein the carrier is a solid include a coarse powder having a particle size, for example, in the range from about 20 to about 500 microns which is administered in the manner in which snuff is taken, i.e., by rapid inhalation through the nasal passage from a container of the powder held close up to the nose. Suitable formulations wherein the carrier is a liquid, for administration, as for example, a nasal spray or as nasal drops, include aqueous or oily solutions of the active ingredient .

Formulations suitable for vaginal administration may be presented as tampons, creams, gels, pastes, foams or spray formulations containing, in addition to Tα_x, suitable carriers.

Formulations suitable for parenteral administration include aqueous and non-aqueous sterile injection solutions which may optionally contain antioxidants, buffers, bacteriostats and solutes which render the formulation isotonic with the blood of the intended recipient; and aqueous and non-aqueous sterile suspensions which may include suspending agents and thickening agents . The formulations may be presented in unit-dose or multi-dose containers, for example, sealed ampules and vials, and may be stored in a freeze-dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example water for injections, immediately prior to use. Extemporaneous injection solutions and suspensions may be prepared from sterile powders, granules and tablets of the kind previously described. It should be understood that in addition to the ingredients particularly mentioned above the formulations of this invention may include other suitable agents having regard to the type of formulation in question, for example, those suitable for oral administration may include flavoring agents. The present invention is applicable to native (i.e., naturally occurring) Tα_x, as well as synthetic T x_ and recombinant Ta_ having the amino acid sequence of native Tα₁₍ amino acid sequences substantially similar thereto, or an abbreviated sequence form thereof, and their biologically active analogs (including muteins) having substituted, deleted, elongated, replaced, or otherwise modified sequences which possess bioactivity substantially similar to that of Tα_x.

The following examples are for illustrative purposes only, and are not to be construed in a limiting sense. Examples

EXAMPLE 1

Preparation of Iniectable Formulation

Pharmaceutical dosage units of 1 ml each are prepared from the ingredients shown in Table 1 below.

TABLE 1 Acti e Ingredient Amount Per mL

Thymosin α-1 0.0064 g

Inactive Ingredients mannitol, U.S. P. 0.050 g sodium phosphate dibasic, heptahydrate, U.S. P. 0.002 g sodium phosphate monobasic, monohydrate, U.S. P. 0.0005 g sodium phosphate dibasic, 2 mg/ml solution sodium phosphate monobasic, 0.5 mg/ml solution water for injection, U.S.P,

EXAMPLE 2

Preparation of In-iectable Formulation

Pharmaceutical dosage units of 1 ml each are prepared from the ingredients shown in Table 2 below.

TABLE 2

Active Ingredient Amount Per mL

Thymosin α-1 0.0032 g

Inactive Ingredients mannitol, U.S. P. 0.050 g sodium phosphate dibasic, heptahydrate, U.S. P. 0.002 g sodium phosphate monobasic,

. monohydrate, U.S. P. 0.0005 g sodium phosphate dibasic, 2 mg/ml solution sodium phosphate monobasic, 0.5 mg/ml solution water for injection, U.S. P.

EXAMPLE 3

Effects of Thvmosin-o^ on CD34+ Stem Cell

Differentiation in Cultured Thvmic Epithelia in vi tro

Material and Methods To evaluate the effect of Tα_x on thymopoiesis, an in vi tro coculture model of thymopoiesis was utilized.

In this model, as set forth in Figure 1, CD34+ stem cells were isolated from bone marrow by positive selection using CD34+ antibody coated beads and immunomagnetic selection, MiniMACS (Miltenyi) . As illustrated in Figure 2, the separation procedure was extremely efficient with >99% of the stem cells expressing CD34+. CD34+ stem cells were a heterogeneous population. Thus, in some experiments, more immature CD34+ population was used, depleted of CD2+CD4+ cells.

Thymus tissue was obtained from children less than 2 years of age undergoing cardiac surgery. The thymic tissue was minced into 1 mm³ fragments and cultured in 1.35 mM 2-deoxyguanosine for 10-14 days in order to deplete the thymic tissue of thymocytes in a 5% C0₂ humidified atmosphere. The thymic fragments were then cultured in growth media (Iscove ' s/Ham' s F-12 media supplemented with 5% FCS and epidermal growth factor) . Subsequently, CD34+ stem cells were cocultured with the cultured thymic epithelia fragments in 24 -well transwell culture plates in Iscove ' s/Ham¹ s F-12 media supplemented with 5% FCS, epidermal growth factor and IL-2 in a 5% C0₂ humidified atmosphere. Approximately 100,000 CD34+ stem cells were cocultured with 3-5 thymic fragments. 10 μg/ml of T x₁ was added to parallel cocultures. Media and Ta_ of cocultures were replaced twice weekly.

At weekly intervals, cultures were harvested to analyze thymocyte subpopulations by flow cytometry. T cell surface phenotypes of the differentiated stem cells were determined by reacting monoclonal antibodies (mAb) conjugated with either fluorescein (FITC) , phycoerythrin (PR) , and peridinin chlorophyll protein (Per-CP) and were then analyzed by flow cytometry. Monoclonal antibodies used are listed in Table 3 below. Combinations of mAbs were used to identify immature thymocytes, such as double-positive (CD3-CD4+CD8+) and triple positive (CD3+CD4+CD8+) thymocytes, and mature CD3+C4+CD8- and CD3+CD4+CD8+ T cells. Analysis of thymocyte subpopulations was performed using WinList software .

Results

Initially, a dose response of Υa_ was performed ranging from 1 to 10 μg/ml . Optimal effects were observed at 10 μg/ml which then was used in subsequent experiments. As shown in Figure 3, Ta_ increased the proliferation of cocultured cells harvested at all time points from the cocultures compared to media alone. Increased proliferation or expansion of thymocytes stimulated by Trχ_ paralleled media alone with peak proliferation observed at 3 weeks, 16.6 versus 10.4 fold increase.

Thymocyte subpopulations were then analyzed to determine whether Tα_x affected thymocyte maturation. As illustrated in Figure 4, Tα_x significantly increased thymocyte CD25+ expression at 1 , 3 and 4 weeks of coculture. Ta_ significantly stimulated CD25+ expression at 1 week, 40% versus 23%, and was significantly increased at 4 weeks, 56% versus 31%.

CD44 and CD25 expression were also evaluated in this model system since CD44 expression appears early in differentiation in the subcapsular cortex prior to expression of TCR, CD3 , CD4 and CD8 , i.e. triple negative thymocytes. Other groups have reported that CD44 plays an important role in thymocyte migration and maturation. As thymocytes further mature through double and triple positive thymocyte stages, CD44 disappears but then reappears in more mature thymocytes . The ligands for CD44 include hyaluronate and fibronectin, matrix proteins which promote cell adhesion. In this model of stem cell differentiation, Tα_x significantly increased CD44+CD25+ expression in the first three weeks of coculture, peaking at 3 weeks 46% versus 30%. See Figure 5. Furthermore, Tα_x increased early thymocyte maturation by increased expression of CD44+25+3- thymocytes at 1 week, 12% versus 7%. See Figure 6. Though Tot_ did not affect CD3 , CD4 CD8 expression, it did increase mature single positive CD3+4+ expression at 3 weeks, 31% versus 23%. Other thymocyte surface phenotypes, such as TCR, CD2 , CD7, CD45RA and CD45RO, were not affected by Tα_x . Thus, Υcx_ dramatically increased CD25 expression throughout the coculture period. It stimulated expression of an early thymocyte, CD44+25+3- pre-T cell, at 1 week of coculture. As thymocytes matured, expression of this thymocyte stage waned similar to control cocultures. Tα_x also promoted expression of mature single positive CD4+ T cells at 3 weeks of coculture. Throughout the coculture period, Tα_x stimulated proliferation of thymocytes. From these studies it is clear that Ta_ promotes T cell differentiation from stem cells.

TABLE 3 Monoclonal antibodies

EXAMPLE 4

Treatment of Adults in Need of Stem Cell

Pifferentiatirpn with τc<_ι

Adult patients in need of stem cell differentiation are selected (e.g., adults with a T cell count of less than 200) .

Each patient receives Tα_x at a dose of 1.6 mg subcutaneously (SQ) every other day.

Outpatient following is initially at one-week intervals for two weeks, then at two-week intervals for two months, and then monthly for the remainder of the treatment period. At each visit the T cell count is monitored.

Drug toxicity is monitored on an ongoing basis using both clinical and laboratory parameters.

While the invention has been described and illustrated with details and references to certain preferred embodiments, those skilled in the art will appreciate that various modifications, changes, omissions, and substitutions can be made without departing from the spirit of the invention.

Claims

What is claimed is :

1. A method of promoting stem cell development in a mammal in need of stem cell development which comprises administering to said mammal a stem cell development enhancing effective amount of Thymosin o^

2. The method of claim 1, wherein said mammal is HIV positive.

3. The method of claim 1, wherein said mammal is in need of a bone marrow transplant.

4. The method of claim 1, wherein the amount of T╬▒_: administered to said mammal is between about 0.1 ╬╝g T╬▒_x per kg body weight of the mammal and about 4.0 ╬╝g T╬▒_: per. kg body weight.

5. The method of claim 4, wherein the amount of T _x administered to said mammal is between about 5 ╬╝g T╬▒j per kg body weight of the mammal and about 65 ╬╝g T╬▒_: per kg body weight.

6. The method of claim 5, wherein the amount of T╬▒_: administered to said mammal is about 20 ╬╝g T╬▒_x per kg body weight of the mammal.

7. The method of claim 1, wherein said mammal is human.

8. The method of claim 1, comprising promoting T cell differentiation from said stem cells.

9. The method of claim 1, wherein said amount is a dosage of about 0.1-10 mg .

10. The method of claim 1, wherein said amount is a dosage of about 0.5-5 mg .

11. The method of claim 1, wherein said amount is a dosage of about 1-2 mg .

12. The method of claim 1, wherein said amount is a dosage of about 1.6 mg .