ABSTRACT
BACKGROUND AND OBJECTIVES: In this study, we evaluated the impact of hyperthermia in photosensitizing efficacy of 3-[(1'-hexyloxy)ethyl-3-devinylpyropheophorbide-a (HPPH or Photochlor) for the treatment of cancer by photodynamic therapy (PDT). STUDY DESIGN/MATERIALS AND METHODS: The outcome of both whole body hyperthermia (WBH) and local hyperthermia (LH) in combination with HPPH-PDT was determined in BALB/c and nude mice bearing Colon26 and U87 tumors, respectively. LH was performed by using an indigenously designed heating device, that was heated to the required temperature using a circulating water bath. The device which has flexible membrane on one side was placed on skin above the tumor. The temperature of the tumor was monitored using a thermocouple sensor placed on the surface of the tumor capable of measuring the temperature within 0.1°C. Uptake of the photosensitizer in tumors was determined by fluorescence using an IVIS or a Nuance Imaging System. The PDT was performed by exposing the tumors to 665 nm laser loght, (135 J/cm2 , 75 mW/cm2 ) at the maximal uptake time of HPPH. Tumor size was measured daily using vernier calipers. RESULTS: The improved PDT efficacy (long-term percentage tumor cure) in combination with hyperthermia is possible due to an increase in tumor-uptake of the photosensitizer (PS), confirmed by in vivo fluorescence imaging and also by increased tumor perfusion and decreased hypoxia as have been reported previously (Sen et al. [2011] Cancer Res. 71:3872-3880 In Vivo. 20:689-695). Interestingly, compared to whole body hyperthermia, the 14 C- HPPH biodistribution data under local hyperthermia showed similar tumor-uptake in BALB/c mice bearing Colon26 tumors, but significantly lower uptake in other organs and in the blood. CONCLUSION: Our study demonstrates that both, fever range whole body and local hyperthermia in combination with HPPH-PDT enhances the long-term tumor cure of BALB/c and nude mice implanted with Colon26 and U87 tumors respectively. Lasers Surg. Med. 50:506-512, 2018. © 2018 Wiley Periodicals, Inc.
Subject(s)
Chlorophyll/analogs & derivatives , Colonic Neoplasms/therapy , Hyperthermia, Induced/methods , Photochemotherapy/methods , Photosensitizing Agents/pharmacology , Animals , Chlorophyll/pharmacology , Colonic Neoplasms/pathology , Disease Models, Animal , Mice , Mice, Inbred BALB C , Mice, NudeABSTRACT
Photodynamic therapy (PDT) of cancer is dependent on three primary components: photosensitizer (PS), light and oxygen. Because these components are interdependent and vary during the dynamic process of PDT, assessing PDT efficacy may not be trivial. Therefore, it has become necessary to develop pre-treatment planning, on-line monitoring and dosimetry strategies during PDT, which become more critical for two or more chromophore systems, for example, PS-CD (Photosensitizer-Cyanine dye) conjugates developed in our laboratory for fluorescence-imaging and PDT of cancer. In this study, we observed a significant impact of variable light dosimetry; (i) high light fluence and fluence rate (light dose: 135 J/cm², fluence rate: 75 mW/cm²) and (ii) low light fluence and fluence rate (128 J/cm² and 14 mW/cm² and 128 J/cm² and 7 mW/cm²) in photobleaching of the individual chromophores of PS-CD conjugates and their long-term tumor response. The fluorescence at the near-infrared (NIR) region of the PS-NIR fluorophore conjugate was assessed intermittently via fluorescence imaging. The loss of fluorescence, photobleaching, caused by singlet oxygen from the PS was mapped continuously during PDT. The tumor responses (BALB/c mice bearing Colon26 tumors) were assessed after PDT by measuring tumor sizes daily. Our results showed distinctive photobleaching kinetics rates between the PS and CD. Interestingly, compared to higher light fluence, the tumors exposed at low light fluence showed reduced photobleaching and enhanced long-term PDT efficacy. The presence of NIR fluorophore in PS-CD conjugates provides an opportunity of fluorescence imaging and monitoring the photobleaching rate of the CD moiety for large and deeply seated tumors and assessing PDT tumor response in real-time.
Subject(s)
Chlorophyll/analogs & derivatives , Colonic Neoplasms/diagnostic imaging , Colonic Neoplasms/drug therapy , Glycoconjugates/pharmacology , Photochemotherapy/methods , Photosensitizing Agents/pharmacology , Radiometry/methods , Animals , Carbocyanines/chemistry , Carbocyanines/pharmacokinetics , Chlorophyll/chemical synthesis , Chlorophyll/pharmacology , Colonic Neoplasms/pathology , Dose-Response Relationship, Radiation , Fluorescent Dyes/chemistry , Fluorescent Dyes/pharmacokinetics , Glycoconjugates/chemical synthesis , Indoles/chemistry , Indoles/pharmacokinetics , Infrared Rays , Mice , Mice, Inbred BALB C , Optical Imaging/methods , Photobleaching , Photochemotherapy/instrumentation , Photosensitizing Agents/chemical synthesis , Propionates/chemistry , Propionates/pharmacokinetics , Singlet Oxygen/chemistry , Singlet Oxygen/metabolism , Spectrometry, Fluorescence/methods , Xenograft Model Antitumor AssaysABSTRACT
Herein we report the syntheses and comparative photophysical, electrochemical, in vitro, and in vivo biological efficacy of 3-(1'-hexyloxy)ethyl-3-devinylpyropheophorbide-cyanine dye (HPPH-CD) and the corresponding indium (In), gallium (Ga), and palladium (Pd) conjugates. The insertion of a heavy metal in the HPPH moiety makes a significant difference in FRET (Förster resonance energy transfer) and electrochemical properties, which correlates with singlet oxygen production [a key cytotoxic agent for photodynamic therapy (PDT)] and long-term in vivo PDT efficacy. Among the metalated analogs, the In(III) HPPH-CD showed the best cancer imaging and PDT efficacy. Interestingly, in contrast to free base HPPH-CD, which requires a significantly higher therapeutic dose (2.5 µmol/kg) than imaging dose (0.3 µmol/kg), the corresponding In(III) HPPH-CD showed excellent imaging and therapeutic potential at a remarkably low dose (0.3 µmol/kg) in BALB/c mice bearing Colon26 tumors. A comparative study of metalated and corresponding nonmetalated conjugates further confirmed that STAT-3 dimerization can be used as a biomarker for determining the level of photoreaction and tumor response.
Subject(s)
Metals/chemistry , Neoplasms, Experimental/pathology , Photochemotherapy , Porphyrins/chemistry , Animals , Fluorescence Resonance Energy Transfer , Mice , Spectrophotometry, UltravioletABSTRACT
We have previously shown that the (124)I-analog of methyl 3-(1'-m-iodobenzyloxy) ethyl-3-devinyl-pyropheophorbide-a derived as racemic mixture from chlorophyll-a can be used for PET (positron emission tomography)-imaging in animal tumor models. On the other hand, as a non-radioactive analog, it showed excellent fluorescence and photodynamic therapy (PDT) efficacy. Thus, a single agent in a mixture of radioactive ((124)I-) and non-radioactive ((127)I) material can be used for both dual-imaging and PDT of cancer. Before advancing to Phase I human clinical trials, we evaluated the activity of the individual isomers as well as the impact of a chiral center at position-3(1) in directing in vitro/in vivo cellular uptake, intracellular localization, epithelial tumor cell-specific retention, fluorescence/PET imaging, and photosensitizing ability. The results indicate that both isomers (racemates), either as methyl ester or carboxylic acid, were equally effective. However, the methyl ester analogs, due to subcellular deposition into vesicular structures, were preferentially retained. All derivatives containing carboxylic acid at the position-17(2) were noted to be substrate for the ABCG2 (a member of the ATP binding cassette transporters) protein explaining their low retention in lung tumor cells expressing this transporter. The compounds in which the chirality at position-3 has been substituted by a non-chiral functionality showed reduced cellular uptake, retention and lower PDT efficacy in mice bearing murine Colon26 tumors.
Subject(s)
Carcinoma, Squamous Cell/radiotherapy , Chlorophyll/analogs & derivatives , Colonic Neoplasms/radiotherapy , Lung Neoplasms/radiotherapy , Photosensitizing Agents/pharmacology , Animals , Biological Transport , Carcinoma, Squamous Cell/metabolism , Carcinoma, Squamous Cell/pathology , Carcinoma, Squamous Cell/ultrastructure , Cell Line, Tumor , Chlorophyll/chemical synthesis , Chlorophyll/chemistry , Chlorophyll/pharmacology , Chlorophyll A , Colonic Neoplasms/metabolism , Colonic Neoplasms/pathology , Colonic Neoplasms/ultrastructure , Epithelial Cells/drug effects , Epithelial Cells/metabolism , Epithelial Cells/pathology , Fibroblasts/drug effects , Fibroblasts/metabolism , Fibroblasts/pathology , Humans , Iodine Radioisotopes , Lung Neoplasms/metabolism , Lung Neoplasms/pathology , Lung Neoplasms/ultrastructure , Mice , Mice, Inbred BALB C , Molecular Imaging/methods , Neoplasm Transplantation , Organ Specificity , Photochemotherapy/methods , Photosensitizing Agents/chemical synthesis , Spirulina/chemistry , Stereoisomerism , Tumor Burden/drug effectsABSTRACT
We report herein a simple and efficient approach to the synthesis of a variety of meso-substituted purpurinimides. The reaction of meso-substituted purpurinimide with N-bromosuccinimide regioselectively introduced a bromo functionality at the 20-position, which on further reaction with a variety of boronic acids under Suzuki reaction conditions yielded the corresponding meso-substituted analogues. Interestingly, the free base and the metalated analogues showed remarkable differences in photosensitizing efficacy (PDT) and tumor-imaging ability. For example, the free-base conjugate showed significant in vitro PDT efficacy, but limited tumor avidity in mice bearing tumors, whereas the corresponding Ni(II) derivative did not produce any cell kill, but showed excellent tumor-imaging ability at a dose of 0.3â µmol kg(-1) at 24, 48, and 72â h post-injection. The limited PDT efficacy of the Ni(II) analogue could be due to its inability to produce singlet oxygen, a key cytotoxic agent required for cell kill in PDT. Based on electrochemical and spectroelectrochemical data in DMSO, the first one-electron oxidation (0.52â V vs. SCE) and the first one-electron reduction (-0.57-0.67â V vs. SCE) of both the free base and the corresponding Ni(II) conjugates are centered on the cyanine dye, whereas the second one-electron reduction (-0.81â V vs. SCE) of the two conjugates is assigned to the purpurinimide part of the molecule. Reduction of the cyanine dye unit is facile and occurs prior to reduction of the purpurinimide group, which suggests that the cyanine dye unit as an oxidant could be the driving force for quenching of the excited triplet state of the molecules. An interaction between the cyanine dye and the purpurinimide group is clearly observed in the free-base conjugate, which compares with a negligible interaction between the two functional groups in the Ni(II) conjugate. As a result, the larger HOMO-LUMO gap of the free-base conjugate and the corresponding smaller quenching constant is a reason to decrease the intramolecular quenching process and increase the production of singlet oxygen to some degree.
Subject(s)
Carbocyanines/chemical synthesis , Nickel/chemistry , Photosensitizing Agents/chemical synthesis , Porphyrins/chemical synthesis , Animals , Bromosuccinimide/chemistry , Carbocyanines/chemistry , Fluorescence , Mice , Molecular Structure , Neoplasms/drug therapy , Optical Imaging , Oxidation-Reduction , Photochemotherapy/methods , Photosensitizing Agents/chemistry , Porphyrins/chemistry , Singlet Oxygen/chemistry , Stereoisomerism , Structure-Activity RelationshipABSTRACT
We have previously shown that a radioactive (123I)-analog of methyl 3-(1'-(iodobexyloxy) ethyl-3-devinylpyropheophorbide-a (PET-ONCO), derived from chlorophyll-a can be used for positron emission tomography (PET) imaging of a variety of tumors, including those where 18F-FDG shows limitations. In this study, the photodynamic therapy (PDT) efficacy of the corresponding non-radioactive photosensitizer (PS) was investigated in a variety of tumor types (NSCLC, SCC, adenocarcinoma) derived from lung cancer patients in mice tumor models. The in vitro and in vivo efficacy was also investigated in combination with doxorubicin, and a significantly enhanced long-term tumor response was observed. The toxicity and toxicokinetic profile of the iodinated PS was also evaluated in male and female Sprague-Dawley rats and Beagle dog at variable doses (single intravenous injections) to assess reversibility or latency of any effects over a 28-day dose free period. The no-observed-adverse-effect (NOAEL) of the PS was considered to be 6.5 mg/kg for male and female rats, and for dogs, 3.45 mg/kg, the highest dose levels evaluated, respectively. The corresponding plasma Cmax and AYClast for male and female rats were 214,000 and 229,000 ng/mL and 3,680,000 and 3,810,000 h * ng/mL, respectively. For male and female dogs, the corresponding plasma Cmax and AYClast were 76,000 and 92,400 ng/mL and 976,000 and 1,200,000 h * ng/mL, respectively.
ABSTRACT
To investigate the impact of mono- and di-ß-galactose moieties in tumor uptake and photodynamic therapy (PDT) efficacy, HPPH [3-(1'-hexyloxy)ethyl-3-devinylpyropheophorobide-a], the meso pyropheophorbide-a [3-ethyl-3-devinyl-pyropheophorbide-a], and the corresponding 20-benzoic acid analogs were used as starting materials. Reaction of the intermediates containing one or two carboxylic acid functionalities with 1-aminogalactose afforded the desired 172- or 20(4')- mono- and 172, 20(4')-di galactose conjugated photosensitizers (PSs) with and without a carboxylic acid group. The overall lipophilicity caused by the presence of galactose in combination with either an ethyl or (1'-hexyloxy)ethyl side chain at position-3 of the macrocycle made a significant difference in in vitro uptake by tumor cells and photoreaction upon light exposure. Interestingly, among the PSs investigated, compared to HPPH 1 the carbohydrate conjugates 2 and 11 in which ß-galactose moieties are conjugated at positions 172 and 20(4') of meso-pyro pheophorbide-a showed similar in vitro efficacy in FaDu cell lines, but in SCID mice bearing FaDu tumors (head & neck) Ps 11 gave significantly improved long-term tumor cure.
ABSTRACT
3-(1'-Hexyloxyethyl)-3-devinylpyropheophorbide-a (HPPH or Photochlor), a tumor-avid chlorophyll a derivative currently undergoing human clinical trials, was conjugated with mono-, di-, and tri-Gd(III)tetraxetan (DOTA) moieties. The T1/T2 relaxivity and in vitro PDT efficacy of these conjugates were determined. The tumor specificity of the most promising conjugate was also investigated at various time points in mice and rats bearing colon tumors, as well as rabbits bearing widespread metastases from VX2 systemic arterial disseminated metastases. All the conjugates showed significant T1 and T2 relaxivities. However, the conjugate containing 3-Gd(III)-aminoethylamido-DOTA at position 17 of HPPH demonstrated great potential for tumor imaging by both MR and fluorescence while maintaining its PDT efficacy. At an MR imaging dose (10 µmol/kg), HPPH-3Gd(III)DOTA did not cause any significant organ toxicity in mice, indicating its potential as a cancer imaging (MR and fluorescence) agent with an option to treat cancer by photodynamic therapy (PDT).
Subject(s)
Colonic Neoplasms , Photochemotherapy , Animals , Chlorophyll/analogs & derivatives , Chlorophyll/pharmacology , Chlorophyll A , Colonic Neoplasms/diagnostic imaging , Colonic Neoplasms/drug therapy , Heterocyclic Compounds, 1-Ring , Humans , Mice , Photochemotherapy/methods , Photosensitizing Agents/pharmacology , Photosensitizing Agents/therapeutic use , Rabbits , RatsABSTRACT
In this report, we present a regioselective oxidation of a series bacteriochlorins, which on reacting with either ferric chloride (FeCl(3)) or 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) yielded the corresponding ring-B or ring-D reduced chlorins. The effect of the number of electron-withdrawing groups present at the peripheral position, with or without a fused isocyclic ring (ring-E), did not make any significant difference in regioselective oxidation of the pyrrole rings. However, depending on the nature of substituents, the intermediate bis-dihydroxy bacteriochlorins on subjecting to pinacol-pinacolone reaction conditions gave various ketochlorins. The introduction of the keto-group at a particular position in the molecule possibly depends on the stability of the intermediate carbocation species. The newly synthesized bacteriochlorins show strong long-wavelength absorption and produced significant in vitro (Colon26 cells) photosensitizing ability. Among the compounds tested, the bacteriochlorins containing a keto-group at position 7 of ring-B with cleaved five-member isocyclic ring showed the best efficacy.
Subject(s)
Ferric Compounds/chemistry , Photosensitizing Agents/chemical synthesis , Porphyrins/chemical synthesis , Benzoquinones/chemistry , Butanones , Magnetic Resonance Spectroscopy , Molecular Structure , Photochemistry , Photosensitizing Agents/chemistry , Porphyrins/chemistry , Quantum Theory , Spectrum Analysis , StereoisomerismABSTRACT
To investigate the importance of the chirality and precise structure at position 3(1') of pyropheophorbide-a for tumor cell specificity and photodynamic therapy (PDT), a series of photosensitizers (PSs) was synthesized: (a) with and without chirality at position 3(1'), (b) alkyl ether chain with a variable number of chiral centers, (c) hexyl ether versus thioether side chain, and (d) methyl ester versus carboxylic acid group at position 172. The cellular uptake and specificity were defined in human lung and head/neck cancer cells. PSs without a chiral center and with an alkyl chain or thioether functionalities showed limited uptake and PDT efficacy. Replacing the methyl group at the chiral center with a propyl group or introducing an additional chiral center improved cellular retention and tumor cell specificity. Replacing the carboxylic acid with methyl ester at position 172 lowered cellular uptake and PDT efficacy. A direct correlation between the PS uptake in vitro and in vivo was identified.
Subject(s)
Chlorophyll/analogs & derivatives , Photosensitizing Agents/metabolism , Animals , Chlorophyll/chemistry , Chlorophyll/metabolism , Chlorophyll/therapeutic use , Head and Neck Neoplasms/drug therapy , Head and Neck Neoplasms/pathology , Humans , Light , Lung Neoplasms/drug therapy , Lung Neoplasms/pathology , Mice , Mice, SCID , Microscopy, Fluorescence , Photochemotherapy , Photosensitizing Agents/chemical synthesis , Photosensitizing Agents/therapeutic use , Solubility , Stereoisomerism , Transplantation, Heterologous , Tumor Cells, CulturedABSTRACT
Erlotinib was covalently linked to 3-(1'-hexyloxy)ethyl-3-devinylpyropheophorbide-a (HPPH) and structurally related chlorins and bacteriochlorins at different positions of the tetrapyrrole ring. The functional consequence of each modification was determined by quantifying the uptake and subcellular deposition of the erlotinib conjugates, cellular response to therapeutic light treatment in tissue cultures, and in eliminating of corresponding tumors grown as a xenograft in SCID mice. The experimental human cancer models the established cell lines UMUC3 (bladder), FaDu (hypopharynx), and primary cultures of head and neck tumor cells. The effectiveness of the compounds was compared to that of HPPH. Furthermore, specific functional contribution of the carboxylic acid side group at position 172 and the chiral methyl group at 3(1') to the overall activity of the chimeric compounds was assessed. Among the conjugates investigated, the PS 10 was identified as the most effective candidate for achieving tumor cell-specific accumulation and yielding improved long-term tumor control.
Subject(s)
Erlotinib Hydrochloride/chemistry , Photosensitizing Agents/chemical synthesis , Porphyrins/chemistry , Animals , Cell Line, Tumor , Cell Survival/drug effects , Coculture Techniques , Female , Head and Neck Neoplasms/drug therapy , Head and Neck Neoplasms/mortality , Head and Neck Neoplasms/pathology , Humans , Mice , Mice, SCID , Photochemotherapy , Photosensitizing Agents/chemistry , Photosensitizing Agents/pharmacology , Photosensitizing Agents/therapeutic use , Stereoisomerism , Structure-Activity Relationship , Survival RateABSTRACT
Conjugates of 3-(1'-hexyloxyethyl)-3-devinyl pyropheophorbide-a (HPPH) with multiple Gd(III)aminobenzyl diethylenetriamine pentacetic acid (ADTPA) moieties were evaluated for tumor imaging and photodynamic therapy (PDT). In vivo studies performed in both mice and rat tumor models resulted in a significant MR signal enhancement of tumors relative to surrounding tissues at 24 h postinjection. The water-soluble (pH: 7.4) HPPH-3Gd(III) ADTPA conjugate demonstrated high potential for tumor imaging by MR and fluorescence. This agent also produced long-term tumor cures via PDT. An in vivo biodistribution study with the corresponding (14)C-analogue also showed significant tumor uptake 24 h postinjection. Toxicological evaluations of HPHH-3Gd(III)ADTPA administered at and above imaging/therapeutic doses did not show any evidence of organ toxicity. Our present study illustrates a novel approach for the development of water-soluble "multifunctional agents", demonstrating efficacy for tumor imaging (MR and fluorescence) and phototherapy.
Subject(s)
Chlorophyll/analogs & derivatives , Gadolinium/therapeutic use , Neoplasms/diagnosis , Neoplasms/drug therapy , Animals , Chlorophyll/chemistry , Chlorophyll/therapeutic use , Fluorescence , Gadolinium/chemistry , Magnetic Resonance Imaging/methods , Mice , Mice, Inbred BALB C , Mice, Inbred C3H , Neoplasms/pathology , Photochemotherapy/methods , RatsABSTRACT
To develop novel bifunctional agents for tumor imaging (MR) and photodynamic therapy (PDT), certain tumor-avid photosensitizers derived from chlorophyll-a were conjugated with variable number of Gd(III)aminobenzyl DTPA moieties. All the conjugates containing three or six gadolinium units showed significant T(1) and T(2) relaxivities. However, as a bifunctional agent, the 3-(1'-hexyloxyethyl)pyropheophorbide-a (HPPH) containing 3Gd(III) aminophenyl DTPA was most promising with possible applications in tumor-imaging and PDT. Compared to HPPH, the corresponding 3- and 6Gd(III)aminobenzyl DTPA conjugates exhibited similar electronic absorption characteristics with a slightly decreased intensity of the absorption band at 660 nm. However, compared to HPPH, the excitation of the broad "Soret" band (near 400 nm) of the corresponding 3Gd(III)aminobenzyl-DTPA analogues showed a significant decrease in the fluorescence intensity at 667 nm.
Subject(s)
Gadolinium DTPA/chemistry , Gadolinium DTPA/pharmacokinetics , Neoplasms/diagnosis , Photosensitizing Agents/chemistry , Photosensitizing Agents/pharmacokinetics , Cell Line, Tumor , Cell Survival/drug effects , Gadolinium DTPA/chemical synthesis , Gadolinium DTPA/pharmacology , Humans , Neoplasms/drug therapy , Photochemotherapy , Photosensitizing Agents/chemical synthesis , Photosensitizing Agents/pharmacologyABSTRACT
To determine the impact of delivery vehicles in photosensitizing efficacy of HPPH, a hydrophobic photosensitizer was dissolved in various formulations: 1% Tween 80/5% dextrose, Pluronic P-123 and Pluronic F-127 in 0.5%, 1% and 2% phosphate buffer solutions (PBS). HPPH was also conjugated to Pluronic F-127, and the resulting conjugate (PL-20) was formulated in PBS. Among the different delivery vehicles, only Pluronic P-123 displayed significant vehicle cytotoxicity, whereas Pluronic F127 was nontoxic. Compared to PL-20, HPPH formulated in Tween80 and Pluronic F-127 showed higher cell-uptake, but lower long-term retention in Colon26 cell compared to PL-20. The higher retention of PL-20 was similarly observed during in vivo uptake with BALB/c mice baring Ct26 tumors. In contrast to the in vitro uptake experiments, PL-20 showed slightly higher uptake compared to HPPH formulated in Tween or Pluronic-F127. A significant difference in pharmacokinetic profile was also observed between the HPPH-Pluronic formulation and PL-20. Under similar in vivo treatment parameters (drug dose 0.47 µmol kg-1 , light dose: 135 J cm-2 at 24 h post-injection of PS), HPPH formulated either in Tween or Pluronic F-127 formulation showed similar in vivo PDT efficacy (20-30% tumor cure on day 60), whereas PL-20 showed 40% tumor cure (day 60).
Subject(s)
Chlorophyll/analogs & derivatives , Neoplasms/drug therapy , Photochemotherapy/methods , Photosensitizing Agents/administration & dosage , Poloxamer/administration & dosage , Animals , Cell Line, Tumor , Chlorophyll/administration & dosage , Humans , Mice , Mice, Inbred BALB C , Xenograft Model Antitumor AssaysABSTRACT
This report presents the synthesis and folate receptor target-specificity of amino-functionalized polyacrylamide nanoparticles (AFPAA NPs) for near-infrared (NIR) fluorescence imaging of cancer. For the synthesis of desired nano-constructs, the AFPAA NPs (hereafter referred to as NPs) were reacted with a NIR cyanine dye (CD) bearing carboxylic acid functionality by following our previously reported approach, and the resulting conjugate (NP-CD) on further reaction with folic acid (FA) resulted in a new nano-construct, FA-NP-CD, which demonstrated significantly higher uptake in folate receptor-positive breast cancer cells (KB+) and in folate receptor over-expressed tumors in vivo. The target-specificity of these nanoparticles was further confirmed by inhibition assay in folate receptor-positive (KB+) and -negative (HT-1080) cell lines. To show the advantages of polyacrylamide (PAA)-based NPs in folate receptor target-specificity, the CD used in preparing the FA-NP-CD construct was also reacted with folic acid alone and the synthetic conjugate (CD-FA) was also investigated for its target-specificity. Interestingly, in contrast to NPs (FA-NP-CD), the CD-FA conjugate did not show any significant in vitro or in vivo specificity toward folate receptors, showing the advantages of PAA-based nanotechnology in delivering the desired agent to tumor cells.
Subject(s)
Breast Neoplasms/diagnostic imaging , Folate Receptors, GPI-Anchored/metabolism , Folic Acid/chemistry , Nanoparticles/chemistry , Optical Imaging/methods , Acrylic Resins/chemistry , Animals , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Carbocyanines/chemistry , Carbocyanines/metabolism , Cell Line, Tumor , Female , Fibroblasts/metabolism , Fibrosarcoma/pathology , Fluorescent Dyes/chemistry , Fluorescent Dyes/metabolism , Folic Acid/metabolism , Glycoconjugates/chemistry , Glycoconjugates/metabolism , Heterografts , Humans , Infrared Rays , KB Cells , Mice , Mice, NudeABSTRACT
Herein we report the positron emission tomography (PET) imaging potential of a 124I-labeled radiopharmaceutical (PET-ONCO). In tumored mice, it shows high uptake in a variety of tumors: brain (GL261, U87), Colon (Colon26), lung (Lewis lung), breast (4 T1), bladder (UMUC3), pancreas (PANC-1) implanted in mice. This agent also shows promise for imaging associated metastatic disease (breast to lung, to bone). Interestingly, the iodinated compound derived from chlorophyll-a, in combination with the corresponding 124I-analog, can serve as a dual imaging agent (PET/fluorescence, complimentary to each other), with an option of photodynamic therapy (PDT). In contrast to Fluorine-18 (half-life 110 min), the Iodine-124 radionuclide has a physical half-life of roughly 4 days. Thus, unlike 18F-FDG, PET-ONCO can be transported longer distances. While the time for optimal tumor-uptake was observed at 24 h, improved tumor contrasts of both primary and metastasis were obtained at 48 and 72 h post- injection (i. v.) of PET-ONCO. In both mice and rats at a single dose study, PET-ONCO did not show any organ toxicity.
Subject(s)
Chlorophyll A/chemistry , Indicators and Reagents/chemistry , Neoplasms/diagnostic imaging , Neoplasms/radiotherapy , Animals , Biological Transport , Chlorophyll A/metabolism , Female , Fluorine Radioisotopes/chemistry , Humans , Iodine Radioisotopes/chemistry , Male , Mice, Inbred BALB C , Optical Imaging , Photochemotherapy , Porphyrins/chemistry , Positron-Emission Tomography , Rats, Sprague-Dawley , Time FactorsABSTRACT
3-(1'-Hexyloxyethyl)-3-devinyl-pyropheophorbide-a (HPPH or Photochlor), a tumor-avid chlorophyll-a derivative currently undergoing human clinical trials, was conjugated at various peripheral positions (position-17 or 20) of HPPH with either Gd(III)-aminobenzyl-DTPA (Gd(III) DTPA) or Gd(III)-aminoethylamido-DOTA (Gd(III) DOTA). The corresponding conjugates were evaluated for inâ vitro PDT efficacy, T1 , T2 relaxivities, inâ vivo fluorescence, and MR imaging under similar treatment parameters. Among these analogs, the water-soluble Gd(III)-aminoethylamido-DOTA linked at position-17 of HPPH, i. e., HPPH-17-Gd(III) DOTA, demonstrated strong potential for tumor imaging by both MR and fluorescence, while maintaining the PDT efficacy in BALB/c mice bearing Colon-26 tumors (7/10 mice were tumor free on day 60). In contrast to Gd(III) DTPA (Magnevist) and Gd(III) DOTA (Dotarem), the HPPH-Gd(III) DOTA retains in the tumor for a long period of time (24 to 48â h) and provides an option of fluorescence-guided cancer therapy. Thus, a single agent can be used for cancer-imaging and therapy. However, further detailed pharmacokinetic, pharmacodynamic, and toxicological studies of the conjugate are required before initiating Phase I human clinical trials.
Subject(s)
Antineoplastic Agents/pharmacology , Chelating Agents/pharmacology , Chlorophyll/analogs & derivatives , Colonic Neoplasms/drug therapy , Gadolinium/pharmacology , Photosensitizing Agents/pharmacology , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Chelating Agents/chemical synthesis , Chelating Agents/chemistry , Chlorophyll/chemistry , Chlorophyll/pharmacology , Colonic Neoplasms/diagnostic imaging , Drug Screening Assays, Antitumor , Gadolinium/chemistry , Humans , Magnetic Resonance Imaging , Mice , Mice, Inbred BALB C , Neoplasms, Experimental/diagnostic imaging , Neoplasms, Experimental/drug therapy , Optical Imaging , Photosensitizing Agents/chemical synthesis , Photosensitizing Agents/chemistryABSTRACT
Two positional isomers of purpurinimide, 3-[1'-(3-iodobenzyloxyethyl)] purpurin-18-N-hexylimide methyl ester 4, in which the iodobenzyl group is present at the top half of the molecule (position-3), and a 3-(1'-hexyloxyethy)purpurin-18-N-(3-iodo-benzylimide)] methyl ester 5, where the iodobenzyl group is introduced at the bottom half (N-substitued cyclicimide) of the molecule, were derived from chlorophyll-a. The tumor uptake and phototherapeutic abilities of these isomers were compared with the pyropheophorbide analogue 1 (lead compound). These compounds were then converted into the corresponding 124I-labeled PET imaging agents with specific activity >1 Ci/micromol. Among the positional isomers 4 and 5, purpurinimide 5 showed enhanced imaging and therapeutic potential. However, the lead compound 1 derived from pyropheophorbide-a exhibited the best PET imaging and PDT efficacy. For investigating the overall lipophilicity of the molecule, the 3-O-hexyl ether group present at position-3 of purpurinimide 5 was replaced with a methyl ether substituent, and the resulting product 10 showed improved tumor uptake, but due to its significantly higher uptake in the liver, spleen, and other organs, a poor tumor contrast in whole-body tumor imaging was observed.
Subject(s)
Anthraquinones/therapeutic use , Chlorophyll/therapeutic use , Iodobenzenes/chemistry , Photochemotherapy , Animals , Anthraquinones/chemistry , Anthraquinones/pharmacokinetics , Chlorophyll/chemistry , Chlorophyll/pharmacokinetics , Chlorophyll A , Iodine Radioisotopes/chemistry , Isomerism , Mice , Neoplasms/diagnostic imaging , Neoplasms/drug therapy , Neoplasms/metabolism , Photosensitizing Agents/chemistry , Photosensitizing Agents/pharmacokinetics , Photosensitizing Agents/therapeutic use , Positron-Emission Tomography , Tissue DistributionABSTRACT
To investigate the electrochemical properties of purpurinimide dyads and electron transfer sites for their reduction and oxidation, a series of dimers with variable C-C linkages were synthesized. For the preparation of these novel structures, the formyl and 2-formylvinyl substituents were regioselectively introduced at positions 3 and 20 of Ni(II) purpurinimides by the Vilsmeier reaction. The Ni(II) complexes were then subjected to the McMurry reaction under two different conditions with unexpected results. For example, the reaction of formyl purpurinimides with TiCl(3)(DME)(1.5) failed to produce the desired C-C dimers, and the starting compounds were recovered almost quantitatively. Under similar reaction conditions, the 20-(2-formylvinyl)purpurinimide also did not dimerize but produced instead unexpected benzoisobacteriochlorins via an intramolecular cyclization. However, treatment of the 3-formyl- and 20-formylpurpurinimides with TiCl(4)/Zn produced corresponding dimers linked with one double bond (trans) in modest yields. Under similar conditions, Ni(II) purpurinimides containing a 2-formylvinyl substituent either at position 3 or at position 20 afforded the respective C-C dimers, where the purpurinimide moieties were joined with a trans-trans-trans hexatriene linker. Molecular modeling data suggest that the nature of the conformational energy difference found in all trans vs trans-cis-trans conformers of the dimers connected by a hexatriene linker at the meso- or beta-position of the macrocycle is not because of the intrinsic conformational energy difference of the linker region, which is identical for both dimers.
Subject(s)
Dimerization , Imides/chemistry , Metalloporphyrins/chemistry , Electrochemistry , Oxidation-Reduction , Spectrophotometry, Ultraviolet , StereoisomerismABSTRACT
Herein we report the synthesis, photophysical properties, positron emission tomography (PET) imaging and photodynamic therapy (PDT) efficacy of methyl 3-(1'-m-iodobenzyloxy)ethyl-3-devinyl-verdin 4 (with or without the 124 I isotope). The PET imaging ability and exâ vivo biodistribution of [124 I]4 were compared with the well-studied methyl [3-(124 1'-m-iodobenzyloxy)ethyl]-3-devinyl-pyropheophorbide-a methyl ester (PET-ONCO or [124 I]2) and [18 F]fluorodeoxyglucose ([18 F]FDG) in BALB/c mice bearing colon-26 tumors. Whole-body PET images of [124 I]4 containing a fused methoxy cyclohexenone ring system showed excellent tumor contrast with time (72>48>24â h post-injection). Exâ vivo biodistribution results indicate that relative to the current clinical standard [18 F]FDG and [124 I]2 in 2 % ethanol formulation, [124 I]4, at the same radioactive dose (25â µCi per mouse), showed higher tumor uptake at 24â h post-injection and longer tumor retention. In biological environments, compound 4 showed lower fluorescence and lower singlet oxygen yield than 2, which is possibly due to higher aggregation caused by the presence of a fused cyclohexenone ring system, resulting in limited inâ vitro/inâ vivo PDT efficacy. Therefore, the chlorophyll-a analogue [124 I]4 provides easy access to a novel PET imaging agent (with no skin phototoxicity) to image cancer types-brain, renal carcinomas, pancreas-in which [18 F]FDG shows limitations.