Damage Threshold of Normal Rat Brain in Photodynamic Therapy

Normal brain tissue response to photodynamic therapy (PDT) must be quantified in order to implement PDT as a treatment of brain neoplasm. We therefore calculated the threshold for PDT-induced tissue necrosis in normal brain using Photofrin (porfimer sodium, Quadralogic Technologies Inc., Vancouver, BC) as the photosensitizer. The absolute light fluence-rate distribution for superficial irradiation and effective attenuation depth were measured in vivo using an invasive optical probe. Photosensitizer uptake in cerebral cortex was measured with chemical extraction and fluorometric analysis. Photodynamic therapy-induced lesion depths at various drug dose levels were measured as a biological end point. The PDT threshold for normal brain necrosis was calculated as in the magnitude of 10¹⁶ photons/cm³. Thus normal rat brain is extremely vulnerable to PDT damage. This suggests that extra precautions must be exercised when PDT is used in brain.     

Measurement of Tumor Vascular Damage in Mice with 99m Tc-MIBI Following Photodynamic Therapy

Abstract— The clinical perfusion agent ^99mTc-MIBI was used to monitor changes in tumor vascular perfusion (TVP) induced by Photofrin® (Pll)-mediated photodynamic therapy (PDT). BALB/c mice bearing an EMT-6 tumor on each hind thigh were given an intravenous injection of 1, 2 or 5 mg kg⁻¹ PII. Twenty-four hours later, one tumor was illuminated (600–650 run, 200 mW cm⁻² 400 J cm⁻²) while the other served as a control. At various time intervals after PDT (0, 2 and 24 h) mice received an intravenous injection of ^99mTc-hexakismethoxy(sobutyusonitri-le (MIBI) (0.18 MBq g⁻¹) and were sacrificed 2 min later. The light-treated and the untreated tumors were then dissected, the radioactivity was counted and the percentage of the injected dose per gram of tumor (%ID g⁻¹) was calculated as a measure of TVP. We observed that TVP is drug dose dependent, develops progressively with time post-PDT and is inversely related to PDT efficacy. Our data show that early tumor retention of ^99mMIBI is a simple method to assess TVP and vascular damage induced by PDT.     

Porphyrin and Nonporphyrin Photosensitizers in Oncology: Preclinical and Clinical Advances in Photodynamic Therapy

Photodynamic therapy (PDT) is now a well-recognized modality for the treatment of cancer. While PDT has developed progressively over the last century, great advances have been observed in the field in recent years. The concept of dual selectivity of PDT agents is now widely accepted due to the relative specificity and selectivity of PDT along with the absence of harmful side effects often encountered with chemotherapy or radiotherapy. Traditionally, porphyrin-based photosensitizers have dominated the PDT field but these first generation photosensitizers have several disadvantages, with poor light absorption and cutaneous photosensitivity being the predominant side effects. As a result, the requirement for new photosensitizers, including second generation porphyrins and porphyrin derivatives as well as third generation photosensitizers has arisen, with the aim of alleviating the problems encountered with first generation porphyrins and improving the efficacy of PDT. The investigation of nonporphyrin photosensitizers for the development of novel PDT agents has been considerably less extensive than porphyrin-based compounds; however, structural modification of nonporphyrin photosensitizers has allowed for manipulation of the photochemotherapeutic properties. The aim of this review is to provide an insight into PDT photosensitizers clinically approved for application in oncology, as well as those which show significant potential in ongoing preclinical studies.     

Fluorescence Photobleaching of ALA-induced Protoporphyrin IX during Photodynamic Therapy of Normal Hairless Mouse Skin: The Effect of Light Dose and Irradiance and the Resulting Biological Effect

The photobleaching of 5-aminolaevulinic acid (ALA)-induced protoporphyrin IX (PpIX) was investigated during superficial photodynamic therapy (PDT) in normal skin of the SKH HRt hairless mouse. The effects of light dose and fluence rate on the dynamics and magnitude of photobleaching and on the corresponding PDT-induced dam-age were examined. The results show that the PDT damage cannot be predicted by the total light dose. Photo-bleaching was monitored over a wide range of initial PpIX fluorescence intensities. The rate of PpIX photo-bleaching is not a simple function of fluence rate but is dependent on the initial concentration of sensitizer. Also, at high fluence rates (50–150 mW/cm², 514 nm) oxygen depletion is shown to have a significant effect. The rate of photobleaching with respect to light dose and the corresponding PDT damage both increase with decreasing fluence rate. We therefore suggest that the definition of a bleaching dose as the light dose that causes a 1/e reduction in fluorescence signal is insufficient to describe the dynamics of photobleaching and PDT-induced dam-age. We have detected the formation of PpIX photoproducts during the initial period of irradiation that were themselves subsequently photobleached. In the absence of oxygen, PpIX and its photoproducts are not photo-bleached. We present a method of calculating a therapeutic dose delivered during superficial PDT that demonstrates a strong correlation with PDT damage.     

Early Events in Photodynamic Therapy: Chemical and Physical Changes in a POPC:Cholesterol Bilayer due to Hematoporphyrin IX-mediated Photosensitization

We studied the interaction of hematoporphyrin IX (HpIX) with bilayers of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) containing cholesterol at a molar fraction between 0 and 0.5. The membrane-associated fraction of HpIX decreases significantly over a period of hours, for porphyrin concentrations in the aqueous phase above 50 n m . This was attributed to self-aggregation of HpIX and was well described by a dimerization process. A model was developed to correct for aggregation and obtain the true partition coefficient which is dependent on the molar fraction of cholesterol with a maximum at 20 mol%. The chemical and physical effects on the lipid bilayer upon irradiation of HpIX were studied for lipid bilayers with POPC:Chol 1:1. Exposure of these bilayers to visible light in the presence of HpIX leads to several cholesterol oxidation products that were identified using GC-MS. A dramatic increase in the membrane leakiness was also observed, even for short irradiation times and small light intensities, as evaluated from the rate of pH equilibration and dithionite permeability. The relevance of these results for the mechanism of photodynamic therapy is discussed.     

The Effect of Fluence Rate on Tumor and Normal Tissue Responses to Photodynamic Therapy

Photodynamic therapy (PDT), carried out at low fluence rates, may enhance tumor response as well as affect treatment selectivity. We have studied the effects of fluence rate on the response of the murine radiation-induced fibrosarcoma (RIF) to PDT using Photofrin® (5 mg/kg). Tumor response was tested over a large range of fluence rates (10-200 mW/cm²) and fluences (25-378 J/ cm²). Low fluence rates were more efficient; -60 J/cm2 at 10 mW/cm² was needed to achieve the same tumor growth delay as -100 J/cm² at 150 mW/cm² and -150 J/cm2 at 200 mW/cm². Despite this increased efficiency, lower fluence rates still required longer treatment times for equivalent anti-tumor effects: 95 min for 57 J/cm² at 10 mW/cm²versus 11 min for 100 J/cm² at 150 mW/cm². Effects of fluence rate on the PDT toxicity to normal tissue were examined through the response of the murine (C311) foot to Photofrin® PDT. Treatment with conditions that produced equivalent tumor responses, i.e. 57 J/cm² at 10 mW/cm² and 100 J/cm² at 150 mW/cm², resulted in a more severe foot response at the higher fluence rate (median peak response: 0.9 at 10 mW/cm², 1.5 at 150 mW/cm²) with more time required for tissue to return to normal (8 days at 10 mW/cm², at least 30 days at 150 mW/cm²). However, when feet were treated with an equal fluence of 100 J/cm2 at various fluence rates, longer healing times accompanied the lower fluence rate treatments. Overall, this paper demonstrates that lower PDT fluence rates are associated with increased efficiency of tumor response. If this increased efficiency is accounted for by lowering treatment fluence, lower fluence rates also may result in a more favorable normal tissue response to treatment.     

Benzoporphyrins and Acetylene-Substituted Porphyrins as Improved Photosensitizers in the Photodynamic Tumor Therapy with Porphyrin Platinum Conjugates

Summary.  A combination of a cisplatinum-like fragment and a porphyrin in the same molecule should not only result in the additivity of the dark toxicity of the platinum fragment and the phototoxicity of the porphyrin moiety, but also in the enrichment of the porphyrin platinum conjugates in tumor tissue, which cisplatinum alone does not show. To increase the penetration depth of the red light used in the photodynamic tumor therapy the conjugated system of the porphyrin components in porphyrin platinum conjugates had to be expanded. Sixteen new (NH₃)₂Pt derivatives of benzoporphyrins and acetylene-substituted porphyrins were synthesized, characterized, and tested with respect to their antitumor activity on the mammary carcinoma cell line MDA-MB-231. Received November 12, 2001. Accepted November 20, 2001     

Ex vivo Application of δ-Aminolevulinic Acid Induces High and Specific Porphyrin Levels in Human Skin Tumors: Possible Basis for Selective Photodynamic Therapy

Abstract— In photodynamic therapy with topically applied δ-aminolevulinic acid porphyrins are acting as photosensitiz-ers. The profile of porphyrin metabolites in normal or in neoplastic skin after administration of δ-aminolevulinic acid has not been determined in detail yet. Thus, to study porphyrin biosynthesis in human skin an organ culture model was developed. Explant pieces of normal skin, ker-atoacanthoma, and basal cell carcinoma were incubated with 1 niM δ-aminolevulinic acid for 36 h. Levels of δ-aminolevulinic acid, porphyrins and porphyrin metabolites were measured in tissues and supernatants. After incubation with δ-aminolevulinic acid, higher porphyrin levels were demonstrated in tumors as compared to normal skin. In supernatants, most of formed porphyrins, preferentially highly carboxylated porphyrin metabolites, were measured. The pattern of synthesized porphyrins differed between normal and neoplastic skin explants. In tissues of basal cell carcinomas protoporphyrin was preferentially shown and tissues of keratoacanthomas were characterized by a predominance of coproporphyrin as compared to normal skin. The results show that explant cultures offer an easy approach to examine the porphyrin biosynthesis of various tissues. The tumor-specific δ-aminolevulinic acid metabolism indicates additional porphyrin metabolites such as coproporphyrin apart from protoporphyrin as effective photosensitizers and may offer a novel approach to tumor-selective photodynamic damage.     

pH-Dependent Chalcogenopyrylium Dyes as Potential Sensitizers for Photodynamic Therapy: Selective Retention in Tumors by Exploiting pH Differences between Tumor and Normal Tissue

Ideal photosensitizers have long-wavelength absorption and strong tumor selectivity with rapid clearance from normal tissues. The telluroselenopyrylium dye 1 that absorbs light at 795 nm (epsilon = 285,000 M-1 cm-1) has a novel property that enhances the tumor specificity and normal tissue clearance. After intralesional injection to both tumors and surrounding skin, it disappeared from the normal skin of BALB/c mice faster than it did from subcutaneously implanted Colon 26 tumors, which resulted in therapeutic selectivity. In vivo reflectance spectroscopy showed that the half-life in tumor was about 50 min while in skin it was around 12 min. This phenomenon appears to be related to the pH differences in normal skin versus tumor, because the rates of drug hydrolysis in solution were shown to be sensitive to changes in pH. Inhibition of tumor regrowth following intratumoral photosensitizer administration depended on both light dose and drug dose, as well as the time interval between dye injection and irradiation; selectivity depended on the time interval. Although treatment parameters were not optimized efficacy was superior to systemic Photofrin under our standard conditions. We discuss how new, more optimal, photosensitizers can be designed that use rates of hydrolysis to exploit the differences in pH between normal tissue and tumor.     

Protection Against UV-Induced Reactive Intermediates in Human Cells and Mouse Skin by Glutathione Precursors: A Comparison of N-Acetylcysteine and Glutathione Ethylester

Because glutathione (GSH) plays a central part in the endogenous defense against UV radiation, an increase in GSH might provide photoprotection. Two agents that increase GSH levels were investigated. Cultured human cells and mouse skin were treated with N -acetylcysteine (NAC) and glutathione ethylester (GSH-Et). After 30 min, the GSH level was determined by HPLC. Photoprotection was assessed by testing the ability of the thiols to scavenge UV-induced reactive intermediates in the same models. As compared to control cells, NAC and GSH-Et increased intracellular GSH in vitro to maximally 144% and 174% respectively. In vitro protection (maximum 23% for NAC and 21% for GSH-Et) did not correlate to the intracellular GSH level but to the concentration of the thiols in the medium. In vivo , epidermal GSH was increased to maximally 163% of the control level by NAC and 1234% by GSH-Et. The maximum in vivo photoprotection provided by GSH-Et was 55%, similar to what was found previously for NAC. Again, the protection seemed more closely correlated to the thiol dose than to the GSH level. The study showed that the protection against UV-induced reactive intermediates depends on a general antioxidant action of these thiols, rather than only on their role as GSH precursors.     

Subcellular Localization of Photofrin and Aminolevulinic Acid and Photodynamic Cross-Resistance in Vitro in Radiation-Induced Fibrosarcoma Cells Sensitive or Resistant to Photofrin-Mediated Photodynamic Therapy

Abstract— The subcellular and, specifically, mitochondrial localization of the photodynamic sensitizers Photofrin and aminolevulinic acid (ALA)-induced protoporphyrin-IX (PpIX) has been investigated in vitro in radiation-induced fibrosarcoma (RIF) tumor cells. Comparisons were made of parental RIF-1 cells and cells (RIF-8A) in which resistance to Photofrin-mediated photodynamic therapy (PDT) had been induced. The effect on the uptake kinetics of Photofrin of coincubation with one of the mitochondria-specific probes 10N-Nonyl acridine orange (NAO) or rhodamine-123 (Rh-123) and vice versa was examined. The subcellular colocalization of Photofrin and PpIX with Rh-123 was determined by double-label confocal fluorescence microscopy. Clonogenic cell survival after ALA-mediated PDT was determined in RIF-1 and RIF-8A cells to investigate cross-resistance with Photofrin-mediated PDT. At long (18 h) Photofrin incubation times, stronger colocalization of Photofrin and Rh-123 was seen in RIF-1 than in RIF-8A cells. Differences between RIF-1 and RIF-8A in the competitive mitochondrial binding of NAO or Rh-123 with Photofrin suggest that the inner mitochondrial membrane is a significant Photofrin binding site. The differences in this binding may account for the PDT resistance in RIF-8A cells. With ALA, the peak accumulations of PpIX occurred at 5 h for both cells, and followed a diffuse cytoplasmic distribution compared to mitochondrial localization at 1 h ALA incubation. There was rapid efflux of PpIX from both RIF-1 and RIF-8A. As with Photofrin, ALA-induced PpIX exhibited weaker mitochondrial localization in RIF-8A than in RIF-1 cells. Clonogenic survival demonstrated cross-resistance to incubation in PpIX but not to ALA-induced PpIX, implying differences in mitochondrial localization and/or binding, depending on the source of the PpIX within the cells.     

Transient Repetitive Exposure to Low Level Light Therapy Enhances Collateral Blood Vessel Growth in The Ischemic Hindlimb of The Tight Skin Mouse

The tight skin mouse (Tsk^?/+) is a model of scleroderma characterized by impaired vasoreactivity, increased oxidative stress, attenuated angiogenic response to VEGF and production of the angiogenesis inhibitor angiostatin. Low‐level light therapy (LLLT) stimulates angiogenesis in myocardial infarction and chemotherapy‐induced mucositis. We hypothesize that repetitive LLLT restores vessel growth in the ischemic hindlimb of Tsk^?/+ mice by attenuating angiostatin and enhancing angiomotin effects in vivo. C57Bl/6J and Tsk^?/+ mice underwent ligation of the femoral artery. Relative blood flow to the foot was measured using a laser Doppler imager. Tsk^?/+ mice received LLLT (670 nm, 50 mW cm^?2, 30 J cm^?2) for 10 min per day for 14 days. Vascular density was determined using lycopersicom lectin staining. Immunofluorescent labeling, Western blot analysis and immunoprecipitation were used to determine angiostatin and angiomotin expression. Recovery of blood flow to the ischemic limb was reduced in Tsk^?/+ compared with C57Bl/6 mice 2 weeks after surgery. LLLT treatment of Tsk^?/+ mice restored blood flow to levels observed in C57Bl/6 mice. Vascular density was decreased, angiostatin expression was enhanced and angiomotin depressed in the ischemic hindlimb of Tsk^?/+ mice. LLLT treatment reversed these abnormalities. LLLT stimulates angiogenesis by increasing angiomotin and decreasing angiostatin expression in the ischemic hindlimb of Tsk^?/+ mice.     

Combined OX40 Agonist and PD-1 Inhibitor Immunotherapy Improves the Efficacy of Vascular Targeted Photodynamic Therapy in a Urothelial Tumor Model

Purpose: Vascular targeted photodynamic therapy (VTP) is a nonsurgical tumor ablation approach used to treat early-stage prostate cancer and may also be effective for upper tract urothelial cancer (UTUC) based on preclinical data. Toward increasing response rates to VTP, we evaluated its efficacy in combination with concurrent PD-1 inhibitor/OX40 agonist immunotherapy in a urothelial tumor-bearing model. Experimental design: In mice allografted with MB-49 UTUC cells, we compared the effects of combined VTP with PD-1 inhibitor/OX40 agonist with those of the component treatments on tumor growth, survival, lung metastasis, and antitumor immune responses. Results: The combination of VTP with both PD-1 inhibitor and OX40 agonist inhibited tumor growth and prolonged survival to a greater degree than VTP with either immunotherapeutic individually. These effects result from increased tumor infiltration and intratumoral proliferation of cytotoxic and helper T cells, depletion of Treg cells, and suppression of myeloid-derived suppressor cells. Conclusions: Our findings suggest that VTP synergizes with PD-1 blockade and OX40 agonist to promote strong antitumor immune responses, yielding therapeutic efficacy in an animal model of urothelial cancer.     

Biodistribution of Photofrin II® and 5-Aminolevulinic Acid-Induced Protoporphyrin IX in Normal Rat Bladder and Bladder Tumor Models: Implications for Photodynamic Therapy

Photodynamic therapy (PDT) has been considered as a potential therapy for superficial bladder carcinomas. Cutaneous photosensitivity and reduction of bladder capacity are the two well-known complications following systemic administration of the commonly used photosensitizer, Photofrin II® (PII). The objective of the present study was to evaluate whether intravesical. (i.b.) instillation of photosensitizers for PDT of bladder cancer might be a more suitable treatment method. Female Fischer rats were utilized to develop orthotopic and heterotopic bladder tumor models. Rats bearing orthotopic bladder tumors were treated either intravesically or intravenously with graded doses of 5-aminolevulinic acid (ALA) or PII. Normal rats received the same doses of ALA or PII. As well, rats bearing heterotopic tumor were studied for comparison. The biodistribution times (times allowed for tissue uptake and bioconversion following drug administration) were 2, 4 or 6 h. Porphyrin fluorescence intensities within tumor, urothelium, submucosa, bladder muscularis and abdominal muscle were quantitated by confocal laser scanning microscopy. Following intravenous (i.v.) injection of ALA, tumor protoporphyrin IX (PpIX) levels peaked at 4 h and diminished by 6 h. The PpIX ratios of tumor-to-bladder mucosa, submucosa and muscle layers were 3:1, 5:1 and 8:1, respectively, 4 h following 1000 mg/kg ALA injection. After ALA instillation, the optimal biodistribution time appeared to be 4 h. Bladder instillation provided comparable tumor labeling with the i.v. route, but lost selectivity of PpIX accumulation between tumor and normal urothelium. The PpIX ratio of tumor-to-bladder muscularis was 5:1. After i.b. instillation of PII, porphyrin fluorescence was detected only within tumor and urothelium, while porphyrin fluorescence was mainly located in bladder submucosa following i.v. injection. Intravesical administration of ALA or PII might be feasible for PDT of superficial bladder cancers.     

Transporting and Shielding Photosensitisers by Using Water‐Soluble Organometallic Cages: A New Strategy in Drug Delivery and Photodynamic Therapy

Skin photosensitivity remains one of the main limitations in photodynamic therapy. In this Concept article a strategy to overcome this limitation is described, in which the photosensitizer is hidden inside the hydrophobic cavity of a water‐soluble organometallic cage. The metallacage not only protects the photosensitizer from light, it also facilitates its delivery to cancer cells.     

Mutagenicity of Photodynamic Therapy as Compared to UVC and Ionizing Radiation in Human and Murine Lymphoblast Cell Lines

Abstract— The mutagenicity of photodynamic therapy (PDT) using red light and either Photofrin® (porfimer sodium) (PF) or aluminum phthalocyanine (AIPc) as the photosensitizer was determined at the thymidine kinase (TK) locus in the human lymphoblastic cell lines, TK6 and WTK1, and was compared to the mutagenicity of UVC and X-radia-tion in these cells as well as the mutagenicity of PDT in murine L5178Y lymphoblastic cell lines. Photodynamic therapy was found not to be mutagenic in TK6 cells, which possess an active p53 gene and which are relatively deficient in recombination and repair of DNA double-strand breaks. In contrast, PDT with either sensitizer was significantly mutagenic in WTK1 cells, which harbor an inactivating mutation in the p53 gene and are relatively efficient in recombination and double-strand break repair as compared to TK6 cells. The induced mutant frequency in WTK1 cells with PF as the photosensitizer was similar to that induced by UVC radiation but lower than that induced by X-radiation at equitoxic faiences/ doses. The mutant frequency induced by PDT in WTK1 cells with either photosensitizer was much lower than that induced in murine lymphoblasts at equitoxic fluences. The TK6 and WTK1 cells did not differ in their sensitivity to the cytotoxic effects of PDT, but the level of PDT-induced apoptosis was greater in TK6 than in WTK1 cells. These results indicate that the mutagenicity of PDT varies in different types of cells and may be related to the repair capabilities as well as the p53 status of the cells.     

Effects of HPV Status on Responsiveness to Ionizing Radiation vs Photodynamic Therapy in Head and Neck Cancer Cell lines

Efficacy of ionizing radiation (I/R) was compared with phototoxic effects of photodynamic therapy (PDT) in vitro using two cell lines derived from patients with head and neck squamous cell carcinoma (HNSCC). A cell line derived from a donor with a human papilloma virus (HPV) infection was more responsive to I/R but significantly less responsive to PDT than a cell line derived from an HPV-free patient. Cell death after I/R in the HPV(+) cell line was associated with increased DEVDase activity, a hallmark of apoptosis. The HPV(−) line was considerably less responsive to I/R, with DEVDase activity greatly reduced, suggesting an impaired apoptotic program. In contrast, the HPV(−) cells were readily killed by PDT when the ER was among the targets for photodamage. While DEVDase activity was enhanced, the death pathway appears to involve paraptosis until the degree of photodamage reached the LD₉₉ range. These data suggest that PDT-induced paraptosis can be a death pathway for cells with an impaired apoptotic program.     

Targeted Photodynamic Therapy of Human Head and Neck Squamous Cell Carcinoma with Anti-epidermal Growth Factor Receptor Antibody Cetuximab and Photosensitizer IR700DX in the Mouse Skin-fold Window Chamber Model

Targeted photodynamic therapy (PDT) in head/neck cancer patients with a conjugate of the anti-epidermal growth factor receptor (EGFR) antibody, Cetuximab and a phthalocyanine photosensitizer IR700DX is under way, but the exact mechanisms of action are still not fully understood. In this study, the EGFR-overexpressing human head/neck OSC-19-luc2-cGFP tumor with transfected GFP gene was used in a skin-fold window chamber model in BALB/c nude mice. The uptake and localization of the conjugate in the tumor and its surrounding normal tissues were studied by an intravital confocal laser scanning microscopy with image analyses. The tumor was also irradiated with 690 nm laser light 24 h after conjugate administration. The vascular and tumor responses were examined by morphological evaluation and immunohistochemistry (IHC). The amount of conjugate in the tumor peaked at 24–48 h after injection. Image analyses of colocalization correlation parameters demonstrated a high fraction of the conjugate IR700DX colocalized in the GFP-expressing tumor cells. PDT-treated tumors showed extensive necrotic/apoptotic destruction with little vascular damage, while IHC showed no HIF-1α expression and decreased EGFR and Ki67 expression with activated caspase-3 overexpression, indicating a direct killing of tumor cells through both necrotic and apoptotic cell death.     

Nucleophilic Aromatic Substitution on Pentafluorophenyl‐Substituted Dipyrranes and Tetrapyrroles as a Route to Multifunctionalized Chromophores for Potential Application in Photodynamic Therapy

The application of porphyrinoids in biomedical fields, such as photodynamic therapy (PDT), requires the introduction of functional groups to tune their solubility for the biological environment and to allow a coupling to other active moieties or carrier systems. A valuable motif in this regard is the pentafluorophenyl (PFP) substituent, which can easily undergo a regiospecific nucleophilic replacement (S_NAr) of its para‐fluorine atom by a number of nucleophiles. Here, it is shown that, instead of amino‐substitution on the final porphyrinoid or BODIPY (boron dipyrromethene), the precursor 5‐(PFP)‐dipyrrane can be modified with amines (or alcohols). These dipyrranes were transformed into amino‐substituted BODIPYs. Condensation of these dipyrranes with aldehydes gave access to trans‐A₂B₂‐porphyrins and trans‐A₂B‐corroles. By using pentafluorobenzaldehyde, it was possible to introduce another para‐fluorine atom, which enabled the synthesis of multifunctionalized tetrapyrroles. Furthermore, alkoxy‐ and amino‐substituted dipyrranes were applied to the synthesis of A₃B₃‐hexaphyrins. The polar porphyrins that were prepared by using this method exhibited in vitro PDT activity against several tumor cell lines.