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The ability to precisely control cell-loaded material systems is essential for in vitro testing of novel therapeutics poised to advance to clinic. In this report, unique patterns of cell migration are devised into an in vitro gel-in-gel model for the purpose of obtaining cell response data to potentially therapeutic chemical agonists. The model consists of co-cultures in a cell-loaded microgel invading an acellular “sorting” gel. Material properties including biophysical and chemical compositions of the sorting gel are carefully controlled to guide a desired cell-specific behavior, leading to massive tumor cell invasion by amoeboid migration mechanisms. Optical transparency enables straightforward and high-throughput measurements of outgrowth response in the presence of either chemical and photoradiation therapy. Important dosing and drug sensitivity information are obtained with the gel-in-gel model using no more than a light microscope, without further need for arduous genomic or proteomic screening of the tissue samples.

Photodynamic therapy (PDT) has been investigated extensively in the laboratory for decades, and for over 25 years in the clinical environment, establishing it as a useful adjuvant to standard treatments for many cancers. A combination of both photochemical and photobiological processes occur that lead to the eventual selective destruction of the tumour cells. It is a potentially valuable adjuvant therapy that can be used in conjunction with other conventional therapies for the treatment of cerebral glioma. PDT has undergone extensive laboratory studies and clinical trials with a variety of photosensitizers (PS) and tumour models of cerebral glioma. Many environmental and genetically based factors influence the outcome of the PDT response. The biological basis of PDT is discussed with reference to laboratory and preclinical studies.

Photodynamic therapy (PDT) is an experimental cancer treatment modality. PDT is based on the accumulation of a photosensitive dye in premalignant and malignant lesions. A certain period of time after the dye has been administered, tumor tissue may contain more of the sensitizer then the surrounding normal tissues. When tissue containing the sensitizer is exposed to light of a proper wavelength and dose, a photochemical reaction between sensitizer and light will occur. The activated photosensitizer reacts with available oxygen which subsequently damages cells and eventually may cause necrosis of the tumor. Photosensitizers can also be used for fluorescence detection. If a tumor contains more of the photosensitizer than the surrounding normal tissue, its fluorescence can potentially be utilized to detect tumors. Analogous to PDT, this can therefore be referred to as photodynamic detection (PDD). This paper reviews the basic mechanisms and clinical applications of PDT and PDD, Emphasis is placed on PDD and PDT with the photosensitizer Photofrin for detection and treatment of premalignant epithelial lesions and squamous cell carcinomas of the oral mucosa.

The ability of a magnetically responsive material to function as a carrier for photosensitizing agents for use in photoradiation therapy (PRT) has been examined in vitro. The photosensitizer has been attached to the magnetically responsive matrix (Dynabeads) by non-specific adsorption, Intralipid-mediated adsorption and poly-L-lysine mediated adsorption. In these studies, it has been demonstrated that conditions of attachment of photosensitizer to the matrix may be adapted in order to facilitate a diffuse or highly localized photo-toxic effect on target cells in vitro. The authors believe that this system may represent a novel approach to targeting photosensitizing agents to specific areas, thereby circumventing some of the problems associated with conventional photoradiation therapy (PRT), particularly in hollow organs.

The principles of photoradiation therapy employing a tumor-seeking agent such as a hematoporphyrin derivative are described. The properties and preparation of hematoporphyrin derivatives and metalloporphyrin synthesis are briefly summarized. We show that PIXE analysis can be used to indicate the degree of a synthesis.

The photonecrotic effectiveness of a morpholinothiolporphyrin derived from haematoporphyrin was measured in an animal model of cerebral glioma. The dose administered was 20 mg kg-1 and the laser dose varied from 0 to 200 J cm-2. The tumour necrosis was at least as good as that of HpD, and this therapeutic response may be attributed to the targeting of specific 'photopotent' subcellular sites.

During a 3 year period, 20 patients with morphologically proven squamous cell carcinoma of the trachea or bronchi have been treated by photoradiation therapy (PRT). A Bulgarian gold vapor laser and hematoporphyrin of `Jacopo Monico,' Italy were used. The photosensitizer was applied intravenously 24 - 48 h prior to PDT. The median realized energy dose was 410 J/cm2 for each patient with a middle power of 180 mW. In 5 of all the cases we performed two sessions. The obtained therapeutic results are as follows: CR -- one case (5%), SR -- 10 cases (50%), NR -- 3 cases (15%). The median survival of the patients with advanced cancer was 13.3 months. At the end of 1990 three patients were alive. Our experience shows that PRT is a promising palliative method in cases of advanced carcinoma for the recanalization of airways.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The uptake of hematoporphyrin derivative (HpD) into human cerebral glioma was measured using a porphyrin extraction technique. Patients with cerebral glioma were injected with HpD at a dose of 5 mg/kg body weight 24 hours before surgery and photoradiation therapy (PRT). Biopsies of tumor, and where possible, adjacent brain and normal brain were taken for analysis of HpD uptake. HpD was selectively localized into all grades of glioma, and there was a direct correlation between the grade of glioma and HpD level in the tumor. The levels were highest in glioblastoma multiforme (mean uptake of 5.9 mg of HpD/g of tumor wet weight) and lower in the intermediate-grade anaplastic astrocytoma (mean uptake of 2.4 mg/g of tumor) and the low-grade astrocytoma (1.6 mg/g of tumor), Uptake into normal brain tissue taken from HpD-sensitized patients was 0.2 mg/g. HpD was also localized into the “brain adjacent to tumor” region. The selective uptake into the low-grade glioma suggests that PRT may be of use as an adjuvant therapy in these tumors and the detection of HpD in this region indicates that PRT may control the spread of tumor infiltrating into the adjacent normal brain.

Lasers now have a wide variety of medical applications, ranging from the dissolution of coronary artery thrombus to the repair of a detatched retina. The main types of laser in medicine are surgical, photocoagulator, photoradiation therapy, and cold lasers which are used by acupuncturists. Cold lasers act directly on cells to improve healing and reduce inflammation. They are also used as an effective substitute for needling or electrical stimulation.

Hematoporphyrin derivative-photoradiation therapy (HPD-PRT) of human malignancy has been performed on 267 tumor sites in 50 patients. Tumor response has been assayed at 24 hours and one month following treatment with 625-635 nm light from an argon laser-pumped dye laser. The majority of tumors treated were dermal breast cancer recurrences (21 cases), local recurrence of ENT squamous cell carcinomas (16 cases), and ENT cutaneous metastases of squamous cell carcinomas (9 cases). A 30-day favorable response was judged to be either complete regression of the tumor or reduction of tumor diameter by greater than 50%. The above categories of tumors had a combined favorable response of 81%. Appropriate dosimetry is discussed.

Thirty-five patients with tumors within the tracheobronchial tree were treated with photoradiation therapy (PRT) employing the photodynamic action of hematoporphyrin derivative (HPD). An effective protocol has been developed consisting of 3.0 mg/kg HPD given intravenously 72 hours prior to the bronchoscopic illumination of the endobronchial tumor sites with red light (630 nm) from an argon pumped dye laser. Light applicators were developed that provided surface (area) and insertion (volume) illumination of tumor masses. Average light dosages of 100 J/cm2 and 200 J/cm were used for surface and insertion illumination, respectively. Delivery rates were 200 mW/cm2 and 400 mW/cm. There was no immediate visible effect such as coagulation or charring noted. All malignant endobronchial tumors responded. Tumors included primary and metastatic lesions of various histologic types. Response was complete for tumor within the bronchus after one treatment in 80% of instances. The remaining cases required two treatments to obtain a complete response due to the extensive length of bronchus involved or because multiple sites were present. A complete response, that is, the full opening up of the lumen to the bronchial wall, was accomplished in all but one instance. Atelectatic lungs or lobes were re-expanded and reaerated. Dyspnea and cough became significantly less. The follow-up achieved to date indicates improvement in symptoms, activity level, and the return to work in a significant number of cases.

Photoradiation therapy (PRT) against the Greene-Harvey amelanotic malignant melanoma on the rabbit iris was effectively used to cause tumor regression. A dose of 2.5 mg/kg of hematoporphyrin derivative (HPD) given intravenously, followed by photoradiation at a wavelength of 632 nm and a power density as low as 71 mW/cm2 for 24 minutes (102 J/cm2) was found to be lethal for tumors 4 mm in diameter with an acceptable level of reversible toxicity to the surrounding tissues. This was best accomplished with a dye laser as the source of light because of its very narrow expanding cone of light, as emitted from a fiber optic. A 1000 Watt xenon arc lamp was also effective but not as efficient. Because of this tumor's exceptionally rapid growth rate, it was necessary to compromise one important variable - the 3 to 4 day period between injection of HPD and photoradiation to allow for HPD depletion from normal tissues. Thus, the best tumor death responses were achieved when the light was given 1 to 16 hours after administering HPD. It is surmised that with this rapidly growing tumor, new cell progeny possess insufficient concentrations of HPD to be killed by the radiant energy. At such a short delay period, toxicity to normal tissues was observed mainly as conjunctivitis and conjunctival chemosis. A dose level of HPD at 5 mg/kg was very close to the threshold where minor increases in light intensity would cause strong inflammatory reactions. Higher doses, at 7.5 and 10 mg/kg were excessive. A dose of 23 mg/kg accompanied by mild light energy exposures, even after 30 days, caused massive damage to normal tissues.

Photodynamic therapy (PDT) by means of gold vapor laser was applied to uterine horns of ovariectomized rats. In 9 of 10 estrogen-primed rats treated with PDT, 3 hours after dihematoporphyrin ether (DHE) intravenous injection, selective necrosis of the endometrium and the inner part of the circular (internal) muscle layer occurred, whereas the contralateral horn (without photoradiation) remained intact. More extensive necrosis resulted in 8 of 10 horns of rats pretreated with estrogen, affecting also the inner part of the longitudinal (external) muscle layer. PDT applied 24 and 48 hours after DHE injection resulted in complete uterine necrosis in 4 estrogen primed and 4 nonprimed uterine horns. We conclude that proper timing of PDT and estrogen priming are important factors in achieving selective uterine layer necrosis in rats.

Visual function for ten patients undergoing HPD-PRT was tested using 1) the Graham Field Eye Chart for distance vision, 2) pseudo-isochromatic plates for color vision, and 3) Amsler grid for changes in macular function. Whereas some increases and decreases in ocular function were observed, no clear patterns or changes of significance were observed.

Summary The therapeutic efficacy of photoradiation therapy (PRT) following hematoporphyrin derivative (HpD) administration was compared in the experimental MS-2 tumour model to that of conventional treatment methods for local control of neoplastic diseases. The therapeutic effects of PRT and surgical removal of primary tumour were comparable in these experiments. However, optimal effects were critically dependent on the stage of tumour development. In addition, the therapeutic advantage of PRT over radiotherapy suggests an interesting role of a new approach in tumours resistant to this conventional treatment.

It is useful for clinicians to have some guidelines on dosage when they first treat a tumour using interstitial photoradiation therapy. A graph is given which may be used to determine the required fibre dose when the corresponding dose and treatment distance are known for external irradiation of the same type of tissue. Optical parameters for a given tumour are not usually known with great accuracy, but this is not a problem because the model is not particularly sensitive to variations of these values within the clinical range.

Exposure of mouse and rat tumors of various types to more than 600 nm light 24 or 48 hours after an injection of hematoporphyrin resulted in a substantial number of long-term cures. Since hematoporphyrin is preferentially retained in tumor tissue, selective tumor destruction could be obtained. Light penetration studies and the high efficiency of this technique indicated its applicability even to certain deep-seated human tumors.

This report discusses the optical and thermal distribution during photoradiation therapy of malignant tumors. Emphasis is put on the therapeutic procedure with the light dose delivered through an inserted optical fiber. Theoretical predictions and experimental results indicate that the temperature rise during the procedure may give rise to hyperthermal cell kill. The report discusses the extent of the regions with hyperthermal bioeffects in terms of tissue parameters as optical absorption and scattering, thermal conductivity, specific heat, blood flow, and optical dose parameters as optical power and exposure time.

Hematoporphyrin derivative (HPD) has the ability to localize with moderate selectivity to tumor tissue, where it can be activated by visible light and produce singlet oxygen-mediated damage to cellular biomolecules. However, HPD is less than ideal as an agent for tumor photoradiation therapy because it produces a period of photosensitivity that can last 30 days or more, and it can be toxic to surrounding tissues such as skin when used in the treatment of subcutaneous metastases. The usefulness of intra-arterial injection for refining the selectivity of HPD was investigated in this work. Intraarterial administration of HPD was not found to provide higher tumor levels of HPD, nor was it able to increase significantly the concentration of HPD relative to surrounding tissues, such as skin and muscle. However, fluorescence microscopy findings suggested that some fluorescent HPD component is rapidly accumulated in tumor macrophages following intraarterial injection.

✓ Intracerebral tumors were produced in 99 rats by stereotaxic implantation of 9L gliosarcoma brain-tumor cells. Hematoporphyrin derivative (HPD), 10 or 20 mg/kg, was administered as an intravenous bolus 24 or 48 hours before irradiation of the tumor region with light from an argon pumped-dye laser (632 nm). Laser light, at a dose of 30, 60, or 200 joules/sq cm, was delivered through a craniectomy 10 or 13 days after tumor implantation. Survival times were significantly prolonged in rats exposed to laser light at a dose of 200 joules/sq cm 24 hours after administration of HPD, 20 mg/kg.

Photoradiation therapy is achieved when a photosensitizing drug is activated by light to form products that are lethal to tumor cells. The most commonly used drug is hematoporphyrin derivative, which is preferentially taken up and retained by malignant tissue. Photoactivation is usually produced by using a dye laser tuned at 630 nm (red light). The primary mechanism of neoplastic cell damage in photoradiation therapy involves the production of free radicals formed during illumination of hematoporphyrin derivative by light of this wavelength. The treatment would seem to damage first the tumor cell membrane, then the cytoplasmic inclusions, and finally the nucleus. Photoradiation therapy has been quite effective in the treatment of superficial malignancies, especially in skin, breast, eye, bladder, bronchus, and stomach. Experience with brain tumors is still limited. Important unresolved problems in the application of photoradiation therapy to gliomas include relative uptake of hematoporphyrin derivative into the tumor, limited light penetration of the tissue, local heating, and damage induced in normal brain by photoradiation therapy.

In the multi-disciplinary treatment of head and neck tumors, anti-cancer chemotherapy was evaluated by the survival rate, response rate and preservation of function and shape. Chemotherapy significantly improved the survival rates in cervical esophageal, hypopharyngeal and maxillary cancer and malignant lymphoma in stage II. A new regimen of Pepleomycin, Vincristine, Endoxan, Mitomycin-C, Predonine, 5-Fu and Adriacin showed a better than partial response in 42% of the patients. Functional preservation with combined chemotherapy was observed only in maxillary cancer.Chemosensitivities for head and neck malignant tumors were measured in order to select useful drugs. Although no concrete merit of these tests has yet been achieved, inoperable recurrent carcinoma or maxillary cancer will be treated by more selective anti-cancer drugs. Furthermore, photoradiation therapy with hematoporphyrin derivatives will become a useful modality for head and neck tumors in the near future, because this technique does not destroy normal tissue.

Photoradiation therapy with hematoporphyrin derivative was used in 13 cases of early-stage and eight cases of stage 1 central-type lung cancer. The lesions were photoradiated superficially or interstitially by an argon dye laser with a power of 80 to 600 mW for 10 to 40 minutes at 48 hours or more after intravenous injection of 2.5 to 5.0 mg of hematoporphyrin derivative (Photofrin) per kilogram of body weight Eight of the 13 early-stage cases were treated with photoradiation only, due to poor pulmonary function or refusal of surgery. Macroscopically complete tumor remission was obtained in all eight cases, and the patients are free of disease at 13 to 41 months after photoradiation therapy, except two patients who died at 16 and 31 months after therapy, due to chronic obstructive pulmonary disease and cerebral infarction, respectively. Five cases were resected following photoradiation therapy. Complete remission was demonstrated histologically in two and significant remission in three, and all are free of disease at 7 to 30 months after surgery. The histologic type was squamous cell carcinoma in all cases. In eight stage 1 cases (seven squamous cell carcinomas and one large cell carcinoma), surgery was performed in three after photoradiation therapy, and the remaining five cases were not resected, due to poor pulmonary function or refusal of surgery. Apparent complete remission was obtained in two of the nonresected cases (one died of cerebral infarction at 27 months, while recurrence occurred 15 months after photoradiation therapy in the other) and significant remission in six. In three nonresected cases with significant remission, two patients died of pneumonia unrelated to the photoradiation treatment at 11 and 4 months, respectively, after such treatment. The reason why only significant remission was obtained in early and stage-1 cases was due to the penetration of the argon dye laser beam being limited due to the location of the tumor or the degree of intrabronchial or extrabronchial growth in eight cases. In one other case the power of the argon dye laser beam was insufficient due to technical difficulties. Indications for photoradiation therapy were discussed in relation to the histologic findings in the specimens following such therapy. Procedures were performed under local anesthesia in all cases. Our results indicate that with present methods, photoradiation therapy is effective in cases of superficial invasion or intramural invasion, but curative effects can hardly be expected in cases growing beyond the normal muscular or cartilaginous layer. In nonsuperficial early-stage lesions, photoradiation therapy should be combined with other methods.

Photoradiation (photodynamic) therapy of endobronchial primary and metastatic lung cancers uniformly results in a complete response--that is, the opening up of totally or partially obstructed bronchi to their walls. The method, employing hematoporphyrin derivative and red laser light from an argon-pumped dye laser, is safe, efficient, and effective. The safety and lack on any complications rest upon the use of light-diffusing cylinder tips, and upon clean-up bronchoscopy to remove tumor debris promptly. The trachea and main and lobar bronchi, as well as segmental and subsegmental bronchi, can be entirely freed of tumor and completely opened up.

✓ The authors have investigated various factors involved in the photoradiation treatment of 9L glioma cells. The cells were grown in tissue culture and exposed to light from a laser source that allowed accurate quantitation of the light energy. Cell death was determined following treatment using the trypan blue exclusion test. It was shown that the treatment is very wavelength-dependent following the absorption spectrum of hematoporphyrin derivative (HPD). The absorption peaks in the lower part of the spectrum are more efficient than those of higher wavelengths. Photoradiation therapy is more effective the higher the concentration of HPD. Intensity of light is a very important factor in calculating the total dose of light necessary for this treatment.

Hematoporphyrin derivative accumulates in malignant brain tumors and, when activated by light, can produce a cytotoxic reaction. A system for utilizing this concept in the treatment of human malignant brain tumors has been developed and tested in a small series of patients. No significant adverse reactions have occurred, and further development and research are planned.

A patient with unresectable lung cancer who was treated by photoradiation using haematoporphyrin derivative and a low-energy argon dye laser was presented. The patient, roentgenographically occult and cytologically positive, had three polypoid tumours diagnosed as squamous cell carcinoma in the trachea and at the bifurcation of the right upper lobe bronchus. Two of the tumours responded completely after the first course of treatment, and the remaining lesion showed a complete response after the second course of treatment. The patient is apparently diseasefree 72 months after treatment. Photoradiation therapy may be a curative form of treatment in certain early-stage cases of lung cancer.

Four patients with gynecologic tumors recurrent either to the vagina or skin were treated with photoradiation therapy. A cytotoxic effect on the tumor was achieved by injecting hematoporphyrin derivative intravenously followed by exposing the treatment area to light of 630 nm from an argon-ion pumped-dye laser 72 hr later. Of seven tumor sites which were treated, one was completely destroyed, two were diminished in volume by more than 30%, and no response was seen in four. Toxicity was limited to one episode of facial edema and first-degree burn after prolonged exposure to bright artificial light. Phototherapy might be a useful treatment of some gynecologic tumors which recur after standard attempts at control of disease. © 1984.

Two patients were treated at 20 different tumor sites by hematoporphyrin derivative (HPD) photoradiation therapy (PRT). An infrared detector was used to record changes in surface temperature during laser exposure. A temperature rise of up to 4.9 degrees C was recorded for a total energy of 15-30 J/cm2 and less than 150 mW/cm2. For 508 mW/cm2 and 15-20 J/cm2 a temperature rise of 7.0 degrees C was detected. The results suggest a possible role of hyperthermia in HPD-PRT.

Three phototherapeutic regimens with photosensitization are now used in dermatology: PUVA (psoralen + UVA), TUV (crude coaltar + UV), PRT (phototherapy with hematoporphyrin derivative). The efficiency of PUVA and TUV is well known in several dermatoses. PRT is now being tested experimentally. For TUV, the lack of a standardized regimen does not allow a clear-cut evaluation of the therapy. For PUVA, late side-effects, particularly carcinogenicity have to be considered. To improve efficiency and minimize the side-effects of PUVA some procedures, such as association with retinoids, pharmaco-kinetic studies for individual adaptation of the therapeutic regimen and the use of new less mutagenic psoralens are helpful. The persistent phototoxicity following treatments with hematoporphyrin derivative constitutes the major side-effect observed, for this phototherapy.