WO2002011539A1

WO2002011539A1 - Methods and compositions for treating skin ulcers by topical photodynamic therapy

Info

Publication number: WO2002011539A1
Application number: PCT/US2001/041611
Authority: WO
Inventors: Rolf-Markus Szeimies; Christoph Abels
Original assignee: Cytopharm, Inc.
Priority date: 2000-08-08
Filing date: 2001-08-08
Publication date: 2002-02-14
Also published as: AU2001285419A1

Abstract

Skin ulcers are treated by applying a topical composition containing a therapeutically effective amount of photosensitizing dye to the skin ulcer, allowing the topical composition to remain on the skin ulcer, thereby permitting the skin ulcer to absorb a therapeutic amount of photosensitizing dye, then irradiating the topical composition with light from a light source emitting at least one wavelength corresponding to an absorption band of the photosensitizing dye for a time sufficient to deliver a therapeutic dose of light energy to the photosensitizing dye. The topical composition is a gel, cream, ointment, solution, liposome, spray, or aerosol containing a photosensitizing dye.

Description

Methods and Compositions for Treating Skin Ulcers by Topical Photodynamic Therapy

BACKGROUND OF THE INVENTION

Field of the Invention:

This invention relates to methods and compositions for treating skin ulcers by topical application of a photosensitizing dye to an ulcer, combined with activation of the photosensitizing dye with light.

Discussion of the Background:

Skin ulcers, such as diabetic foot ulcers, pressure sores, and chronic venous leg ulcers, are open sores or lesions of the skin characterized by the wasting away of tissue and sometimes accompanied by formation of pus. Skin ulcers may have different causes, and affect different populations, but they all tend to heal very slowly, if at all, and can be quite difficult and expensive to treat.

Eighteen million or more individuals in the USA have diabetes mellitus; 15% to 20% will develop a foot ulcer; 14% to 24% of those that develop a foot ulcer will require an amputation (60,000 p. a.) because other ailments associated with diabetes — such as nerve damage and visual and circulatory problems ~ make it difficult for patients to feel or see the ulcer as it develops. The average cost attributed to foot ulcer care over a 2-year-period in a 40-to 65-year-old male was estimated at nearly $28,000. The standard of care for diabetic foot ulcers (DFUs) consists of extensive debridement of necrotic tissue, dressing the wound with saline-moistened gauze, treatment of infection, off-loading to reduce pressure, and revascularization, if indicated. Approximately 76% of DFUs do not attain complete healing within a 12-week period by standard therapy.

Pressure sores (decubitus ulcers) are particularly common in the disabled, elderly and bedridden population of hospitals and nursing homes. Up to one-third of all patients in the hospital over the age of 70 have pressure sores. The essential cause is ischaemia due to sustained or repeated pressure applied to the skin surface. Nearly all pressure ulcers develop over the following sites: sacral bone, greater trochanter, ischial tuberosity, tuberosity of the calcaneus and lateral malleolus. Management and treatment comprises mainly prevention and relief of pressure. Bedsores are often under treatment for months and sometimes even years with daily application of generally ineffective anecdotal therapies. Such anecdotal therapies range from mechanical devices such as cotton filled doughnuts, air filled mattresses, rotating beds, Clinitron beds, foam mattresses and air suspension mattresses, to a variety of topical preparations which are applied locally to the wound area including "debriders" or enzyme preparations to eat away the dead cells so that the living cells may survive, topical antibiotics to treat infections of the area, betadine washes, normal saline rinses, hydrogen peroxide soaks, wet to dry dressings, occlusive dressings, silvadine ointments, elase ointments and travase ointment. In cases of persisting ulcers classical topical therapies as for chronic venous leg ulcers or diabetic ulcers are commonly used.

Eighty to 90%) of all leg ulcers, constituting the major complication of peripheral vascular diseases, are due to superficial or deep venous insufficiency. Because of dermatoliposclerosis and a disorder of perfusion and diffusion of the lower limbs there is a decreased pO₂ in the tissue resulting in cutaneous necrosis aggravated by slight traumata, e.g. scratching or bumping. When the ulcers are open, they tend to be present for some time. In various studies, half of all such ulcers had been open for 9 - 12 months, 20% open for two years and 8% open for over five years. Healing of these ulcers is impaired due to stasis dermatitis resulting from increased leukocyte-endothelium interaction in the postcapillary venules. In addition superinfection with bacteria - usually staphylococci - yields a fibrous, odorous smear further inhibiting wound healing. Even when they do heal, leg ulcers seem to have a typical cycle of healing followed by re-ulceration and re-healing.

Therapeutic approaches to healing chronic leg ulcers aim first of all to restore the impaired venous flow in the leg by compression or surgical intervention. However, an adjuvant local therapy is mandatory to accelerate the healing of the ulcer. The first step is to cleanse the ulcer, second to fight local superinfection and third to stimulate both granulation via influencing the cytokine network and reepithelization of the ulcer.

During the past three decades, an accelerating volume of research has been conducted and published concerning the use of photodynamic therapy (PDT) in the treatment of hyperproliferative diseases such as the treatment of cancerous tumors and skin disorders. A selective summary of relevant patent and scientific literature references to PDT research and clinical applications is covered, for example, in U.S. Patent 5,610,175, Vogel et. al, where each references cited in turn offers many more references. Photodynamic Therapy (PDT) is a bimodal treatment, employing a photosensitizer and a light source, and has been used historically primarily for treating superficial non- melanoma skin cancer (von Tappeiner and Jesionek, Therapeutische Versuche mit fluorescirenden Stoffen, Mtinch Med Wochenschr 47:2042-2044, 1903; Karrer et al., The use of photodynamic therapy for skin cancer, Onkologie 21:20-27, 1998). Recently, however, PDT has also been shown to be effective in the treatment of inflammatory dermatoses, e.g. psoriasis (Boehncke et al., Treatment of psoriasis by topical photodynamic therapy with polychromatic light, Lancet, 343: 801, 1994) or scleroderma (Karrer et al., Topical photodynamic therapy for localized scleroderma, Acta Derm Venerol (Stockh) 80: 26-27, 2000), not responding to conventional therapy.

The PDT technique is based upon the delivery to the target tissue of the photosensitizer, normally a photosensitizing dye. The dye is then exposed to light comprised of a wavelength corresponding to an absorption band of the dye, whereupon the dye molecules are exited to an excited singlet state. Once in the excited singlet state, the dye molecule can either decay back to the ground state (either by fluorescence or non-radiative decay processes), or by intersystem crossing processes enter an excited triplet state. In the excited triplet state, the dye molecules can transfer energy to other molecules, such as oxygen. In the latter case, energy transfer to oxygen results in the formation of singlet oxygen and other reactive oxygen species (ROS). For a review, see: Pass, Photodynamic therapy in oncology: mechanisms and clinical use, J. Natl. Cancer Inst 85: 443-456, 1993. These ROS induce cytotoxic as well as immunomodulatory effects depending on the photosensitizer localization, concentration and light intensity.

The photosensitizer may be applied either systemically or topically. The first modern photosensitizer to receive regulatory approvals in numerous countries is Photofrin^® which, however, is administered by intravenous injection. Photofrin^® has been approved for use in PDT treatment of oesophageal, lung and bladder cancers, plus other solid tumors. However, i.v. injection of Photofrin^®, a complex mixture of many porphyrinoid derivatives, is known to cause occasional generalized cutaneous photosensitisation for up to 8 weeks, sometimes giving rise to severe phototoxic reactions. In dermatology, this major side effect is not acceptable for the treatment of superficial skin cancer or inflammatory dermatoses. Therefore a topical application is preferred. A new extensively studied photosensitizer which can be applied topically is 9-Acetoxy-2,7,12,17-tetrakis-(β-methoxyethyl)porphycene (ATMPn), a porphycene with functionalized side chains, which already has shown its effectiveness in clinical trials for PDT treatments of psoriasis. However, although the topical compositions currently used for treating psoriasis are effective for the treatment of ulcers and bedsores, they typically have a low viscosity and contain alcohols. Low viscosity topical compositions tend to wash off of the wound site when applied to wet ulcers, and alcohol based compositions can cause pain and irritation when applied to open wounds. Superior formulations lack alcohol content and are more viscous.

Hitherto, the primary target applications of PDT have been for the treatment of diseases characterized by hyperproliferative tissues (cancer, restenoses, psoriasis, etc.) with the photosensitising dye concentrating in, and then destroying, the target cells when exposed to light. Wound treatments using systemically applied PDT have been evaluated, but were not found to influence wound healing (Parekh et al., Lasers in Surgery and Medicine, 24: 375-381, 1999).

In addition, a single PDT with Photofrin^® was found to be capable of killing Staphylococci spp. {S. aureus andS. epidermidis) in vitro (Karrer et al., Photodynamic inactivation of staphylococci with 5-aminolevulinic acid or Photofrin, Lasers Med Sci, 14: 54-61, 1999), and porphycenes related to ATMPn have been demonstrated to possess remarkable broad anti-microbial properties against Gram-positive and Gram negative bacteria, yeasts and fungi (Jori et al., U.S. Patent Application No. 09/289,637). However, there have been no reports of topically applied dyes in successful PDT treatments which promote wound healing of skin ulcers, bed sores, etc.

Most recently, PDT with systemically applied methylene blue as a photosensitizer was found to inhibit intimal hyperplasia and promote the healing of arterial walls (Heckenkamp et al, Local photodynamic action of methylene blue favorably modulates the postinterventional vascular wound healing response, J Vascular Surgery, 31(6): 1168-1177, 2000).

SUMMARY OF THE INVENTION Accordingly, one object of the present invention is a method of treating skin ulcers by topical application of a photosensitizing dye to an ulcer followed by activation with light. Another object of the present invention is a topical composition comprising a photosensitive dye.

These and other objects of the present invention are made possible by the discovery that photosensitizing dyes, applied topically for short periods of time to otherwise slow- healing sores and ulcers and combined with short exposures to light, can accelerate wound- healing. A wide range of photosensitizers, topically-applied and combined with low light doses and light intensity (below the threshold required for induction of necrosis or apoptosis), can be employed in PDT methods of healing skin ulcers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Suitable photosensitive dyes are those compounds which, upon irradiation with light of an appropriate wavelength, convert oxygen into singlet oxygen. Suitable compounds include porphycenes, porphyrins, chlorins, phthalocyanmes, naphthalocyanines, texaphyrins, purpurins, biogenetic precursors of endogenous protoporphyrin IX (acid modified δ- aminolevulinic acids), and mixtures thereof. Acid modified δ-aminolevulinic acid, may describe modification of the free carboxylic acid function (e.g., as an ester or amide; in its free form δ-aminolevulinic acid acts as an unacceptable irritant to ulcerated tissue or wounds). Preferably the photosensitive dye is a porphycene compound.

As non-limiting examples of suitable porphycene compounds there are compounds of the formula :

where R¹, R², R³ and R⁴ are each independently

(a) -(CH₂)_n -X, where n=l-20, X is H, OR⁵,CN, OH, OSO₂ R⁵ , NH₂ , NHR⁵, NR⁵ ₂, SH, SR⁵ , S(O),.₂ R⁵ , COOH, CO₂ R⁵ , C(O)NH₂ , C(O)NHR⁵ , C(O)NR⁵ ₂, halogen or CHO, where and R⁵ is C_1-20 alkyl, aralkyl or aryl;

(b) -(CH₂)_m CH=CH₂ where m is 0-2;

(c) -(CH₂)_n -O-G where G is a mono- or oligosaccharide;

(d) -(CH₂)_2n -X, where X is an amino acid, oligopeptide covalently bonded by an ether-, ester- or amine-bond or -Y-(CH₂)_π -porphycene² (porphycene² being a compound of the same structure, where n is 0-8, and Y is a direct bond, -O-, -CH₂-CH₂-, or-CH= H-); or

(e) where one, two or three of the substituents R¹ are C,.₆ alkyl or aryl and the remaining substituents are as above under (a)-(d), and salts and metal complexes thereof;

Z is H or a substituent covalently bound to the porphycene macrocycle through an oxygen atom or a nitrogen atom, as exemplified by ethers (-OR, where R is alkyl, aryl, or aralkyl), esters, amides, etc., and may bear at least one carboxylic acid function through which Z may be conjugated to a poly ly sine moiety via an amide link.

ATMPn is a preferred porphycene compound according to formula I, where R¹, R², R³, and R⁴ all are CH₃OCH₂CH₂-, and Z is CH₃CO₂-; typically in an amount of 0.001 to 5.0 wt.%, preferably in an amount of 0.01 to 1.0 wt.%.

Non-limiting examples of suitable porphycene compounds are disclosed in U.S. 4,913,907, 5,015,478, 5,132,101, 5,179,120, 5,244,671, 5,262,401, 5,409,900, 5,610,175, and 5,637,608 as well as U.S. 09/289,637, filed on April 12, 1999, the relevant portion of each is which describes the porphycene compounds are hereby incorporated by reference. Other useful photoactivatable compounds include Photofrin^® and Photosan^®, verteporfin, chlorins, texaphyrins, purpurins, phthalocyanmes, methylene blue, hypericin, etc. Photofrin^® and Photosan^® are a complex mixture of porphyrinoid molecules derived from processed bovine or porcine blood. Photophrin^® is available from QLT Therapeutics and Photosan^® is available in Germany from SeeLab. The structure of a benzoporphyrin derivative, verteporfin, available from QLT Therapeutics is shown below. Chlorins are po hyrin- or chlorophyll-derived compounds which strongly absorb light at wavelengths of more than 650 nm. Representative chlorin structures, i.e., mono-aspartyl chlorin e6, produced by Nippon Petrochemical, meso-tetra(m-hydroxyphenyl)chlorin, produced by Scotia Pharmaceuticals, and meso-tetra(m-hydroxyphenyl)bacteriochlorin are shown below. Purpurin has the structure shown below. The tin etiopurpurin derivative (SnEt₂) is available from Miravant. Representative phthalocyanmes have the structures shown below. The zinc phthalocyanine complex is available from Ciba-Geigy (Novartis).

benzoporphyrin derivative

mono-aspartyl chlorin e₆

meso-tetra(m-hydroxyphenyl)chlorin

meso-tetra(m-hydroxyphenyl)bacteriochlorin

purpurin

phthalocyanine

naphthalocyanine The porphycene compounds suitable for the present method may be made by conventional methods known to those of ordinary skill in the art, such as by analogy to the techniques taught in the references cited above.

As described above, topically applied PDT compositions containing a photosensitizing dye, such as ATMPn, may be applied to the sore or ulcer for specific intervals, preferably 0.25 to 12 hours, while covered with bandages. If the photosensitizing dye penetrates the ulcer readily, shorter incubation times (e.g., 0.25 to 3 hours) may be used. For photosensitizing dyes which penetrate the ulcer more slowly, longer incubation times may be necessary (e.g., 3 to 12 hours). Incubation times of approximately 6 hours, however, allow sufficient penetration of the photosensitizing dye into the ulcer, with minimal itching, burning, and irritation of the ulcer site. A short incubation interval on the wound area prevents deep penetration of the photosensitizing dye (Karrer et al., Topical application of a first porphycene dye for photodynamic therapy —penetration studies in human perilesional skin and basal cell carcinoma, Arch Dermatol Res, 289: 132-137, 1997). The bandage is then removed and the area is irradiated with light at a wavelength corresponding to the absorption band of the photosensitizing dye. For example, porphycene dyes such as ATMPn absorb at a wavelength of approximately 640 nm. The energy intensity of the light applied is lower than that typically used for tumor destruction, about 5-40 J/cm². The light source may be either a coherent source, such as a laser, or an incoherent or polychromatic light source. A non-limiting example of the light source may be an incoherent light source, such as the Waldmann PDT 1200L, made by Waldmann Medizintechnik, Villingen-Schwenningen, FRG. This light source can be used to deliver light having an intensity of 1-250 mW/cm². More typically, light of 40 mW/cm² intensity is employed. Light sources manufactured by other companies having similar light intensities may also be employed. The total light dose applied to the ulcer may be, for example, 10 J/cm². Different light doses may be used depending on the nature of the ulcer treated and the photosensitizing dye employed. For example, light doses of up to 20 J/cm² may be employed. A light dose of 20 J/cm² may typically require irradiation of the ulcer for approximately 5.5 min., using a light source with an intensity of 60 mW/cm². This process can be repeated two to three times a week until the ulcer heals. An example of a suitable treatment schedule for an ulcer, preferable already debrided, s as follows:

1. A topical formulation containing approximately 0.1% ATMPn is applied to the ulcer, at a dosage of approximately 20-100 μl of the formulation per cm² of ulcer surface. Contamination of adjacent tissue may be avoided, however, since the composition typically has low penetration properties for intact skin. Contamination of adjacent tissues does not result in tissue damage.

2. The ulcer site is then covered with an opaque and liquid-tight bandage. For example, plastic films such as polyvinylidene chloride, polyethylene, etc., cloth, or aluminum foil may be employed as components of the bandage.

3. The ulcer site is then incubated for a varying time period, depending on the composition of the formulation. Typically, incubation times of 3-6 hours are preferred.

4. At the end of the incubation period, the residual photosensitizing dye is removed from the surface of the ulcer, for example by wiping the ulcer with sterile gauze or a sterile swab.

5. The ulcer may then be irradiated with a suitable light source.

6. After irradiation, the ulcer is then covered with a standard wound dressing, for example a wet wound dressing.

7. The above PDT schedule may be repeated 2 to 3 times per week. For example the PDT treatments could be carried out on a Monday/Thursday schedule (two treatments per week), or a Monday/Wednesday/Friday schedule (three treatments per week).

Any photosensitizing dye that can be activated by a light source to generate ROS is suitable, provided that the dye, and/or a formulation containing the dye, is not unacceptably toxic or a severe irritant. In addition to ATMPn, other photosensitizing dyes may be employed. The actual dose of the dye, the duration of contact with the ulcer prior to illumination, and the wavelength and intensity of the light source used are all factors which must be specifically optimized for each dye selected. For example, if the photosensitizing dye is Photofrin^®, it may be mixed into a gel base at a concentration of 1 mg Photofrin^®/ml of gel. During the application of the formulation to the ulcer, contamination of adjacent healthy skin is preferably avoided, but in any case will not lead to significant tissue damage because ATMPn does not penetrate in significant amounts into intact, healthy skin. The formulation may be applied either at a medical facility, by a doctor or nurse, or may be applied by the patient.

The topical composition used in the present process comprises a photosensitizing dye in a carrier.

The porphycene compounds of the present invention may be formulated for topical application in penetrating solvents or in the form of a lotion, cream, ointment, spray or gel containing a sufficient amount of the porphycene compound to be effective for PDT therapy.

Typical non-toxic topical vehicles known in the pharmaceutical arts may be used. Topical vehicles may include water and pharmaceutically acceptable water-miscible organic solvents such as ethyl alcohol, isopropyl alcohol, propylene glycol, glycerin, propylene carbonate, and the like, and mixtures of these solvents. These compositions should not be toxic to the ulcer tissue, and may also contain conventional additives such as humectants, emollients, lubricants, stabilizers, and perfumes, provided that the additives do not interfere with the therapeutic properties of the composition. Preferably the vehicle does not substantially contribute to irritation of the wound, and for this reason ethyl alcohol and isopropyl alcohol are not preferred.

Suitable humectants include, but are not limited to aloe vera gel, squalane, glycerol stearate, polyethylene glycol, cetyl alcohol, stearic acid, propylene glycol, glycerin, sorbitan, and the like, and mixtures thereof. Humectants, when employed, may be present in amounts from about 0-20% by weight, preferably about 0-10%, by weight of the composition.

Suitable emollients include, but are not limited to guerbet alcohols (such as isocetyl alcohol or isostearyl alcohol); esters (such as isopropyl palmitate, isopropyl isostearate, octyl stearate, hexyl laurate and isostearyl lactate); a liquid mixture of hydrocarbons which are liquids at ambient temperatures (such as petroleum distillates and light mineral oils); and ethanol. Emollients, when employed, may be present in amounts of 0-70%, by weight, preferably 0-25% of the total weight of the composition

Suitable lubricants may include, for example, the polyglycerylmethacrylate lubricants available under the trademark Lubrajel® from Guardian Chemical Corporation, 230 Marcus Blvd., Hauppage, N.Y. 11787. Suitable Lubrajels include Lubrajel TW, Lubrajel CG and Lubrajel MS, Lubrajel WA, Lubrajel DV and so-called Lubrajel Oil.

Suitable stabilizers include oil-soluble antioxidants, for example butyl hydroxytoluene, butyl hydroxyanisole, -, β-, γ-, and δ-tocopherol, nordihydrogualaretin, propyl gallate, fatty acid esters of ascorbic acid, ascorbic acid salts, isoascorbic acid, isoascorbic acid salts, sorbic acid and sorbic acid salts.

The topical formulations contain a sufficient amount of the porphycene compound to be effective in PDT therapy. Generally, concentrations in the range of 0.001 to 5 wt. %, preferably from about 0.025 to 1 wt. %, may be used.

Additional topical formulations which may be used in conjunction with the porphycene compounds of the present invention are disclosed in U.S. Pat. Nos. 3,592,930 and 4,017,615 (hereby incorporated by reference).

Topical formulations may be prepared in gel form by combining the porphycene with a solvent such as propylene carbonate, polyethylene glycol, diethyltoluamide (DEET), diisopropyl adipate (DIP A), or combinations thereof, and adding a gelling agent. A preferred gelling agent is fumed silica (CAB-O-SIL.RTM., Cabot Corp., Tuscola, 111.), and particularly grade M-5. The gelling agent is generally used in amounts of about 5-12 wt % to obtain a gel with the desired viscosity. Obviously, gels containing more or less gelling agent will have slightly higher or lower viscosity. One skilled in the art can readily obtain the desired gel viscosity by adjusting the concentration of gelling agent. Additives, such as cosolvents and/or surfactants, frequently improve the gel properties and may be added as desired. Suitable cosolvents/surfactants include propylene glycol and glycerine. The additives may be incorporated into the gel by mechanically mixing the additives into a mixture of solvent and gelling agent.

Actual methods of preparing such dosage forms are known, or will be apparent, to those skilled in this art. The topical PDT composition to be administered will, in any event, contain a quantity of the photosensitizing dye sufficient to achieve the desired therapeutic effect.

Topical application is a critical factor when treating skin sores using PDT, since it limits penetration of the dye below surface tissues. We note that systemic application of BPD-MA (verteporfin) and a CASP (a phthalocyanine) failed to yield wound-healing (Parekh et al., 1999). In addition to the antimicrobial effect, data from our group have shown that the PDT induces in vitro the production of metalloproteinases, in particular MMP-1, and of cytokines and growth factors, e.g. bFGF, PDGF or TGF-β, in fibroblasts and keratinocytes (unpublished data). These effects may yield an accelerated wound healing, simply achieved by applying the photosensitizer topically to the ulcers and irradiating with a coherent or incoherent light source afterwards. The efficacy of the topical PDT can be determined by planimetric measurements of the wound area from digital images of the wound (using conventional image processing techniques) and the bacterial colonization can be measured prior to, during, and after treatment. Insight into the pathophysiological changes in the microcirculation induced by PDT can also be obtained by assessing the tissue oxygenation (tpO2) using planar sensors. In addition, observation of the morphology and the quantification of the skin capillaries of the ulcer margin before and after topical PDT can be undertaken.

Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

Claims

Claims:

1. A method of treating a skin ulcer comprising: i) applying a topical composition comprising a therapeutically effective amount of photosensitizing dye to the skin ulcer, and ii) activating said photosensitizing dye by irradiation with light.

2. The method of Claim 1 , wherein said photosensitizing dye is at least one dye selected from the group consisting of poφhycenes, poφhyrins, chlorins, phthalocyanines, naphtholocyanines, texaphyrins, puφurins, biogenetic precursors of endogenous protopoφhyrin IX (acid modified aminolevulinic acid), methylene blue, and mixtures thereof.

3. The method of Claim 1, wherein said photosensitizing dye is a poφhycene.

4. The method of Claim 3, wherein said poφhycene compound is of the formula

where R¹, R², R³ and R⁴ are each independently

(a) -(CH₂)_n -X, where n=l-20, X is H, OR⁵,CN, OH, OSO₂ R⁵ , NH₂ , NHR⁵, NR⁵ ₂, SH, SR⁵ , S(O)_1-2 R⁵ , COOH, CO₂ R⁵ , C(O)NH₂ , C(O)NHR⁵ , C(O)NR⁵ ₂, halogen or CHO, where and R⁵ is C_1-20 alkyl, aralkyl or aryl; (b) -(CH₂)_m CH=CH₂ where m is 0-2;

(c) -(CH₂)_n -O-G where G is a mono- or oligosaccharide;

(d) -(CH₂)_2n -X, where X is an a ino acid, oligopeptide covalently bonded by an ether-, ester- or amine-bond or -Y-(CH₂)_n -poφhycene² (poφhycene² being a compound of the same structure, n is 0 to 8 and Y is a direct bond, -O-, -CH₂-CH₂- or -CH=CH-); or

(e) where one, two or three of the substituents R¹ are C_1-6 alkyl or aryl and the remaining substituents are as above under (a)-(d), and salts and metal complexes thereof;

Z is H or a substituent covalently bound to the poφhycene macrocycle through an oxygen atom or a nitrogen atom.

5. The method of Claim 4, wherein Z is selected from the group consisting of alkyl ethers, aryl ethers, aralkyl ethers, alkyl esters, aryl esters, aralkyl esters, alkyl amides aryl amides, aralkyl amides, alkyl amines, aryl amines, and aralkyl amines.

6. The method of Claim 4, wherein Z is conjugated to a polylysine moiety via an amide link.

7. The method of Claim 1, wherein said photosensitizing dye is mixture of poφhyrinoid molecules derived from processed bovine or porcine blood.

8. The method of Claim 1, wherein said topical composition is in a form selected from the group consisting of gels, creams, ointments, solutions, liposomes, sprays, and aerosols.

9. The method of Claim 1, wherein said photosensitive dye is activated by irradiation with light of wavelength of about 640 nm.

10. The method of Claim 9, wherein a light dose in the range of 5-40 J/cm² is delivered.

11. The method of Claim 10, wherein said light source is a coherent or incoherent light source capable of providing light having a wavelength range of 500 to 700 nm.

12. The method of Claim 1, wherein said topical composition remains on the skin ulcer for 0.25-6 hours before irradiation with the light source.

13. The method of Claim 1, wherein said photosensitizing dye is benzopoφhyrin derivative monocarboxylic acid (BPD-MA) and said irradiation is at a wavelength of 600 to 700 nm.

14. The method of Claim 13, wherein said irradiation is at a wavelength of approximately 690 nm.

15. The method of Claim 1, wherein said photosensitizing dye is Photofrin^® or Photosan^® and said irradiation is at a wavelength of 500 to 700 nm.

16. The method of Claim 15, wherein said irradiation is at a wavelength of approximately 690 nm.

17. The method of Claim 1, wherein said photosensitizing dye is of the formula

and X is C or N and Y is a single or double carbon-carbon bond; and if X is C, each of R⁶ and R⁷ is independently a hydrogen, or a substituted or unsubstituted alkyl or aryl group; and if X is N, there is no R⁷ substituent and each R⁶ is independently a hydrogen, or a substituted or unsubstituted alkyl or aryl group; and adjacent R⁶ groups may together comprise a fused benzene or naphthalene ring structure.

18. The method of Claim 1, wherein the photosensitizing dye is endogenous protopoφhyrin IX generated through application to the skin ulcer a 0.5-20%) formulation of δ-aminolevulinic acid with the carboxylic acid function protected as an ester or amide and maintaining the δ-aminolevulinic acid formulation in contact with the skin ulcer for 0.5-12 hours before irradiation with blue or red light.

AMENDED CLAIMS

[received by the International Bureau on 11 December 2001 (11.12.01); original claims 1-18 replaced by new claims 1-9 (2 pages)]

1. A method of treating a skin ulcer or wound comprising: i) applying a topical composition comprising a therapeutically effective amount of a poφhycene photosensitizing dye to the skin ulcer or wound, ii) activating said photosensitizing dye by irradiation with light; and iii) repeating steps i) and ii) on a schedule of 2 to 3 times per week.

2. The method of Claim 1, wherein said poφhycene compound is of the formula

where R¹, R², R³ and R⁴ are each independently

(a) -(CH₂)_π -X, where n=l-20, X is H, OR⁵,CN, OH, OSO₂ R⁵ , NH₂ , NHR⁵, NR⁵ ₂, SH, SR⁵ , S(O)_1-2 R⁵ , COOH, CO₂ R⁵ , C(O)NH₂ , C(O)NHR⁵ , C(O)NR⁵ ₂, halogen or CHO, where and R⁵ is C_1-20 alkyl, aralkyl or aryl;

(b) -(CH₂)_m CH=CH₂ where m is 0-2;

(c) -(CH₂)_n -O-G where G is a mono- or oligosaccharide;

(d) -(CH₂)_2n -X, where X is an amino acid, oligopeptide covalently bonded by an ether-, ester- or amine-bond or -Y-(CH₂)_n -poφhycene² (poφhycene² being a compound of the same structure, n is 0 to 8 and Y is a direct bond, -O-, -CH₂-CH₂- or -CH=CH-); or

(e) where one, two or three of the substituents R¹, R², R³ and R⁴ are C,_₆ alkyl or aryl and the remaining substituents are as above under (a)-(d), and salts and metal complexes thereof;

3. The method of Claim 2, wherein Z is selected from the group consisting of alkyl ethers, aryl ethers, aralkyl ethers, alkyl esters, aryl esters, aralkyl esters, alkyl amides aryl amides, aralkyl amides, alkyl amines, aryl amines, and aralkyl amines.

4. The method of Claim 2, wherein Z is conjugated to a polylysine moiety via an amide link.

5. The method of Claim 1, wherein said topical composition is in a form selected from the group consisting of gels, creams, ointments, solutions, liposomes, sprays, and aerosols.

6. The method of Claim 1, wherein said photosensitive dye is activated by irradiation with light of wavelength of about 640 nm.

7. The method of Claim 6, wherein a light dose in the range of 5-40 J/cm² is delivered.

8. The method of Claim 7, wherein said light source is a coherent or incoherent light source capable of providing light having a wavelength range of 500 to 700 nm.

9. The method of Claim 1, wherein said topical composition remains on the skin ulcer or wound for a time to allow sufficient penetration of said photosensitizing dye into said skin ulcer or wound, before irradiation with the light source.