DNA damage and repair in Gorlin syndrome and normal fibroblasts after aminolevulinic acid photodynamic therapy: a comet assay study.

Using normal, untransformed, human fibroblasts, the effectiveness of aminolevulinic (ALA)-mediated photodynamic therapy (PDT) was investigated in terms of both clonogenic survival and DNA damage. The response of normal fibroblasts was then compared with Gorlin syndrome-derived fibroblasts (basal cell nevus syndrome [BCNS]). In terms of clonogenic survival, no significant differences were observed between the two groups of cells. Using the alkaline comet assay, initial DNA damage after PDT was measured. Some DNA damage was detected at higher doses, but this was fully repaired within 24 h of treatment. The BCNS-derived cells showed levels of initial damage that did not differ significantly from normal lines.

Pulsed ultrasound measurements of depth and regression of basal cell carcinomas after photodynamic therapy: relationship to probability of 1-year local control.

BACKGROUND: The regression of clinical basal cell carcinoma (BCC) after photodynamic therapy (PDT) is poorly understood, but is potentially important when, as is increasingly the case, a second treatment is contemplated. High-frequency pulsed ultrasound provides noninvasive information on skin and lesion thickness. OBJECTIVES: To relate pulsed ultrasound measurements before and after PDT to the probability of local control of BCC by PDT. METHODS: Skin thickness and lesion thickness were measured by 20-MHz pulsed ultrasound in 181 patients diagnosed as having BCC. Maximal lesion thickness was determined by repeatedly sampling the BCCs. Measurements were made immediately prior to PDT with aminolaevulinic acid plus 630 nm visible light, and then at 1, 6 and 12 months. RESULTS: Skin thickness in individual patients did not vary with time in this study (mean +/- SD 2.3 +/- 0.6 mm; P = 0.8). In contrast, BCC mean +/- SD maximal thickness 4-6 weeks after PDT was significantly smaller than pretreatment (0.6 +/- 0.8 mm vs. 1.3 +/- 0.8 mm; P < 0.001). The overall probability of 1-year local control fell from 85% when only BCCs

Comparison of the cellular molecular stress responses after treatments used in bladder cancer.

OBJECTIVE: To investigate the molecular stress responses related to the quality of recovery of normal tissue after various treatments for bladder cancer, i.e. hyperthermia, ionizing radiation, mitomycin-C and 5-aminolaevulinic acid photodynamic therapy (ALA-PDT). MATERIALS AND METHODS: The study focused particularly on intracellular fibroblast levels of heat-shock protein-47 (HSP47) and HSP72, which are associated with collagen metabolism and the development of tolerance to repeated treatment, respectively. Iso-effective treatment doses (50% clonogenic cell survival) of each method were delivered to a 3T6 murine fibroblast model. Intracellular extracts were analysed at 3, 6, 9, 12 and 24 h after treatment, using Western blot analysis to compare the levels of HSP47 and HSP72. Time-matched treatment and control groups were quantified by comparison with actin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression using appropriate software. RESULTS: There were various changes in levels of HSP expression with treatment method; HSP47 levels were significantly higher after hyperthermia and radiation but not with mitomycin-C or ALA-PDT. HSP72 levels were significantly higher with all methods except ALA-PDT. CONCLUSIONS: Hyperthermia and ionizing radiation are associated with early increases in levels of HSP47 (a marker of collagen metabolism), in contrast to ALA-PDT and mitomycin-C. These findings are compatible with clinical findings where fibrosis/scarring is common with the first two but not the last two methods. In addition, all methods except ALA-PDT are associated with an increase in HSP 72 (a protein associated with cellular tolerance) and this may help to explain, at a cellular level, why resistance to repeated ALA-PDT treatments does not seem to occur.

Non-invasive pulsed ultrasound quantification of the resolution of basal cell carcinomas after photodynamic therapy.

The probability of local control of basal cell carcinomas (BCC) treated by photodynamic therapy (PDT) depends strongly on lesion thickness, thicker lesions often requiring two treatments. We examine the utility of 20 MHz pulsed ultrasound (US) for the non-invasive measurement of thickness and rate of regression after PDT treatment. PDT was by topically applied 20% aminolaevulinic acid, followed at 6 h by a standard 100 J/cm(2) of 630 nm light. Patients ( n=60) were selected as being difficult to treat with existing modalities for reasons of likely poor quality of healing or of cosmesis in this very largely elderly population. Ultrasound 'A' scans were made immediately before treatment, and at first and subsequent follow-ups. Parameters measured non-invasively for BCC, adjacent normal skin, and for fibroses after previous conventional therapies, were (a) thickness of skin or lesion, (b) linear density of ultrasound echoes and (c) linear density of high-amplitude echoes. Prior to treatment, median skin thickness (to the dermal/subcutaneous boundary) was 2.6 mm (range 1.2-5.7), fibroses 2.5 mm (1.4-5.6) and BCC 1.5 mm (0.5-4.4). Median linear density of echoes for normal skin, fibroses and BCC plus underlying tissue were 5.6, 5.5 and 4.5, respectively, the BCC values being significantly lower ( p=0.002). The corresponding medians for high-amplitude echoes were 1.9, 1.9 and 1.1 (skin or fibrosis versus BCC, p=0.001). Patients whose BCCs appeared clinically to be controlled at up to 220 days after a single treatment, all had values of ultrasound parameters corresponding to skin/fibrosis and were significantly different from measurements on the same site prior to treatment. Patients whose tumours appeared to be reverting to the original BCC ultrasound pattern were subsequently found to be recurring as judged clinically. Non-invasive pulsed ultrasound indicates that rates of resolution vary widely between BCC of similar initial thickness and that the probability of clearance of BCC by PDT is determined largely by the deepest, sometimes small, regions within a lesion, with the overall area being relatively unimportant.

Comparative analysis of foetal calf and human low density lipoprotein: relevance for pharmacodynamics of photosensitizers.

The effects of differences in lipoprotein content on the distribution of the novel hydrophobic photosensitizer n-butyl-3-[18-(2-butylcarbamoyl-ethyl)-3,7,12,17-tetramethyl-18,13-divinyl-22,24-dihydro-porphin-2-yl]propionamide (PP-N-3) and haematoporphyrin ester (HpE), a relatively hydrophilic photosensitizer, in human (HS) and foetal calf sera (FCS), were investigated. The binding characteristics of human and foetal calf low-density lipoprotein (LDL) were characterised using a human fibroblast line (Vag 12). The uptake into cells of HpE and PP-N-3 was also examined. A comparison of the lipoprotein content, composition and receptor-binding characteristics of foetal calf and human serum was also carried out. LDL content was measured directly using sequential ultracentrifugation to isolate LDL. In our study, we found haematoporphyrin ester to bind to human very low-density lipoprotein (VLDL), LDL and high-density lipoprotein (HDL) in the ratio 2:31:65. In the case of PP-N-3 this ratio was 56:10:33. As VLDL was not detected in foetal calf serum, only binding to LDL and HDL was observed. Using the sequential ultracentrifugation technique, foetal calf serum was found to contain LDL which in turn did bind to human LDL receptors. The uptake of PP-N-3 and HpE in the presence of low density lipoprotein from foetal calf serum (FC-LDL) was not significantly different to values observed in the presence of human serum low density lipoprotein (HS-LDL).

Photodynamic therapy for superficial bladder cancer under local anaesthetic.

OBJECTIVES: To evaluate the use of local anaesthesia (LA) in 5-aminolaevulinic acid (ALA) photodynamic therapy (PDT) for superficial transitional cell carcinoma (TCC) of the bladder, and to provide further toxicity and tolerability data on this new method within the context of a phase 1 trial. PATIENTS AND METHODS: ALA PDT was administered to 19 patients with recurrent superficial TCC (stage Ta/carcinoma in situ, grades 1-3) using escalating doses of ALA (3-6%) and 633 nm laser light (25-50 J/cm2) under various LA (lignocaine) protocols. Pain was assessed using a linear analogue scale from 0 to 10. The endpoints of tolerability and toxicity were assessed for the different LA, light and ALA doses, with lignocaine levels. RESULTS: ALA PDT is painful and requires some form of anaesthesia. The discomfort was immediate, associated with bladder spasm, and was a function of the ALA concentration rather than the total light dose given. Simple passive diffusion (PD) of 2% lignocaine instilled for 40 min before PDT gave adequate anaesthesia with 3% ALA (n=8; median pain score 1, range 0-2). With 6% ALA the pain was dramatically increased using PD (n=6; median pain score 8, range 5-10) and therefore the more potent LA technique of electromotive drug administration (EMDA) of 2% lignocaine was used, with excellent results (n=3; median pain score 1, range 0-2). All patients had transient bladder irritability that typically lasted 9-12 days, with no subjective/objective change in long-term bladder function. No other toxicity was reported. Serum lignocaine levels were minimal. CONCLUSION: Bladder ALA PDT is both safe and feasible under LA. At a dose of 3% ALA, the procedure was well-tolerated using PD of lignocaine. At higher doses (6% ALA) more effective anaesthesia is required and this can be obtained satisfactorily with EMDA of lignocaine. With refinement, ALA PDT may be feasible as an outpatient treatment for superficial bladder TCC.

In vivo expression of the collagen-related heat shock protein HSP47, following hyperthermia or photodynamic therapy.

Heat shock protein 47 (HSP 47), a molecule expressed constitutively in cells that synthesise collagen, is involved in collagen type I biosynthesis, and after insult acts as a stress response molecule to sequester abnormal procollagen. Photodynamic therapy (PDT) is claimed not to result in extensive collagen damage, such as that which can occur after other laser treatments, e.g. hyperthermia (HT) or coagulation, thereby conferring on PDT a potential therapeutic advantage. In previous studies on mouse fibroblasts in vitro we demonstrated HSP47 elevation in the first hours after the application of conditions known to damage collagen, and an absence of HSP47 elevation following PDT with two well-established photosensitisers, haematoporphyrin ester (HpE) and meta-tetrahydroxyphenylchlorin (mTHPC). The present study examines HSP47 metabolism in murine skin following (1) HT, (2) PDT with HpE and (3) PDT with riboflavin (RB). Riboflavin was examined because of reports of collagen injury induced by its photoactivation. All three stresses were applied at grossly equitoxic, 'tolerance' doses. Three months after these doses, linear extensometry revealed the skin to have fibrotic characteristics after HT and RB PDT, but not after HpE PDT. HSP47 expression levels were analysed at transcriptional (Northern) and translational (Western) levels at early time intervals up to 24 h after the treatment application, starting immediately after the treatment for mRNA and 6 h post-treatment for protein. Highly significant upregulation of HSP47 was detected following HT, and PDT with RB. PDT mediated by HpE did not have any impact on HSP47 levels. These results were thus consistent with those from in vitro work and support the hypothesis of early elevation of HSP47 expression only by modalities affecting collagen or its precursors.

Photodynamic therapy for large or multiple patches of Bowen disease and basal cell carcinoma.

BACKGROUND: Photodynamic therapy (PDT) using topical delta-aminolevulinic acid (delta-ALA) is an effective treatment for Bowen disease and certain basal cell carcinomas (BCCs), but its place in clinical practice remains to be established. Patients with large and/or multiple lesions of Bowen disease or BCC can represent a considerable therapeutic challenge. We suggest that delta-ALA PDT may be of particular benefit in such patients. OBSERVATION: In an open study, 35 (88%) of 40 large patches of Bowen disease, all with a maximum diameter greater than 20 mm, cleared following 1 to 3 treatments of delta-ALA PDT, although 4 patches recurred within 12 months. delta-Aminolevulinic acid PDT was also used to treat 40 large BCCs, with an identical 88% initial clearance (after 1-3 treatments), with 4 recurrences within 34 months (range, 12-60 months). In 10 further patients with multiple (> or =3) patches of Bowen disease, 44 (98%) of 45 patches cleared following delta-ALA PDT, although 4 lesions recurred over 12 months. In 3 patients with multiple BCCs, PDT cleared 52 (90%) of 58 lesions, with 2 recurrences during 41 months (range, 12-52 months). Treatments were well tolerated, with only 5 patients with solitary large lesions requiring local anesthesia. CONCLUSIONS: delta-Aminolevulinic acid PDT is an effective tissue-sparing modality achieving good cosmesis. We propose that delta-ALA PDT be considered as a first-line therapy for large and/or multiple areas of Bowen disease and superficial BCCs.

Radiation response and cure rate of human colon adenocarcinoma spheroids of different size: the significance of hypoxia on tumor control modelling.

PURPOSE: To evaluate the adequacy of a Poisson tumor control probability (tcp) model and the impact of hypoxia on tumor cure. METHODS AND MATERIALS: A human colon adenocarcinoma cell line, WiDr, was grown as multicellular spheroids of different diameters. Measurements were made of cell survival and spheroid cure following 300-kV X-ray external beam irradiation in air and nitrogen. Cell survival data were fitted using a two-compartment and an oxygen diffusion model. Spheroid cure data were fitted using the tcp model. RESULTS: Hypoxia was seen only for spheroids greater than 500 microm in diameter. For small spheroids tcp estimates of radiosensitivity and clonogenic number showed excellent agreement with experimentally derived values. For large spheroids, although tcp estimates of radiosensitivity were comparable with measurements, estimates of the clonogenic number were considerably lower than the experimental count. Reoxygenation of large spheroids before irradiation resulted in the tcp estimates of the number of clonogenic cells agreeing with measured values. CONCLUSIONS: When hypoxia was absent, the tcp model accurately predicted cure from measured radiosensitivity and clonogen number. When hypoxia was present, the number of cells capable of regrowth in situ was considerably lower than the number of clonogenic cells that initially survived irradiation. As this counteracted the decreased radiosensitivity, hypoxia was less important for cure than predicted from cell survival assays. This finding suggests that chronic hypoxia may not limit directly the success of radiation therapy.

Immunological and viral factors associated with the response of vulval intraepithelial neoplasia to photodynamic therapy.

Topical 5-aminolevulinic acid-based photodynamic therapy (PDT) has produced complete response rates of >90% for nonmelanoma skin carcinomas, which are mostly human papillomavirus (HPV) negative. Using a similar treatment protocol, we observed a short-term response in only one third (10 of 32) of high-grade vulval intraepithelial neoplasia (VIN 2-3) lesions. Unifocal lesions were found more responsive than multifocal and pigmented lesions. Animal model studies have suggested that long-term PDT response involves an immune reaction in which CTLs play a crucial role. In this study, we have assessed: (a) HPV infection; (b) HLA expression; and (c) immune infiltrating cells in VIN biopsies from responders and nonresponders to determine whether these factors may limit response to topical 5-aminolevulinic acid-based PDT. Tissues from normal vulva (n = 9), vulval carcinoma (n = 11), and VIN (32 patients from which 19 pre- and 43 post-PDT biopsies were taken) were investigated for immune cell infiltration and HLA class I expression by immunohistochemistry and HPV infection by PCR. There was a greater likelihood of HPV positivity associated with a lack of response of VIN to PDT (P = 0.002), and VIN nonresponders were more likely to show HLA class I loss compared with responders (P = 0.030). HLA class I down-regulation was significantly greater in the carcinomas (82%, total loss) than the VIN (28%, 19%, total loss; and 9%, allele loss; P = 0.004). None of the cases with class I down-regulation responded to PDT, whereas 3 of 6 (50%) of cases that showed total class I loss subsequently developed superficial invasion. Compared with normal vulval skin, VIN lesions showed increased infiltration by CD4 (T-helper) and CD68 (macrophages) but not CD1a (Langerhans cells) or CD8 (CTLs). There was, however, a significant increase of CD8 infiltration in posttreatment VIN responders compared with nonresponders (P = 0.0001). These data clearly support the contention that high-risk HPV infection and lack of cell-mediated immunity may play a role in the observed poor response of lower genital lesions to topical PDT.

Photodynamic therapy for superficial bladder cancer.

In photodynamic therapy, a photosensitizing drug is activated by visible light and in the presence of oxygen, results in local cell death. This evolving modality is now being used to treat and palliate a very wide variety of human solid tumors and carcinoma-in-situ lesions. With regard to bladder cancer, advances in drug development and modern light delivery techniques mean that photodynamic therapy shows promise in the treatment of superficial bladder cancer resistant to conventional treatments.

Light penetration in bladder tissue: implications for the intravesical photodynamic therapy of bladder tumours.

OBJECTIVES: To assess (i) the optical properties and depth of penetration of varying wavelengths of light in ex-vivo human bladder tissue, using specimens of normal bladder wall, transitional cell carcinoma (TCC) and bladder tissue after exposure to ionizing radiation; and (ii) to estimate the depth of bladder wall containing cancer that could potentially be treated with intravesical photodynamic therapy (PDT), assuming satisfactory tissue levels of photosensitizer. Materials and methods The study included 11 cystectomy specimens containing invasive TCC (five from patients who had previously received external-beam bladder radiotherapy, but with recurrent TCC) and three 'normal' bladders removed from patients treated by exenteration surgery for extravesical pelvic cancer. Full-thickness bladder wall and tumour samples were taken from these specimens and using an 'intravesical' and a previously validated interstitial model, the optical penetration depths (i.e. the tissue depth at which the light fluence is 37% of incident) were calculated at wavelengths of 633, 673 and 693 nm. RESULTS: There were no significant differences in light penetration between normal and tumour-affected bladder tissue at each wavelength. There were significant differences in light penetration among wavelengths; light at 693 nm penetrated approximately 40% further than light at 633 nm (P < 0.002). The light currently used in bladder PDT (633 nm) has a mean (SEM) optical penetration depth of 4.0 (0.1) mm within TCC. In addition, at this wavelength, there was 29% greater light penetration in previously irradiated than in unirradiated bladder wall (P = 0.001). This did not occur in the tumour-affected bladder. CONCLUSIONS: Bladder tissue is relatively more translucent than other human tissues and there is therefore great potential for PDT in the treatment of bladder cancer. As there is no difference in light penetration between TCC and normal bladder tissue, a tumour-specific response with diffuse illumination of the bladder will depend on drug localization within the tumour. The currently used wavelength of 633 nm can be expected to exert a PDT effect within bladder tumour up to a depth of 20 mm. Increasing the wavelength will allow deeper pathology to be treated.

Comparison of red and green light in the treatment of Bowen's disease by photodynamic therapy.

BACKGROUND: A variety of protocols exist for the treatment of Bowen's disease by photodynamic therapy (PDT) using topical 5-aminolaevulinic acid (5-ALA). OBJECTIVE: To determine the optimal wavelength (red or green light) for this treatment. METHODS: A randomized comparison study of ALA-PDT using red (630 +/- 15 nm) or green (540 +/- 15 nm) light in the treatment of Bowen's disease. RESULTS: The initial clearance rate for lesions treated by red light was 94% (30 of 32) in comparison with 72% (21 of 29) for those lesions receiving green light (P = 0.002). Over the following 12 months, there were two recurrences in the red light group and seven in the green light group reducing the clearance rates to 88% and 48%, respectively. The frequency and severity of pain experienced were similar between the two treatment groups. No hyperthermia, nor significant difference in lesional temperatures, was observed between the wavelengths studied. CONCLUSION: Green light is less effective than red light, at a theoretically equivalent dose, in the treatment of Bowen's disease by topical ALA-PDT.

Natural HPV immunity and vaccination strategies.

BACKGROUND: the task of preventing premature death in women may be delivered by vaccinating against the high-risk papillomaviruses associated with various malignancies. OBJECTIVES: we will discuss the immune mechanisms likely to be relevant to the control of an HPV infection in the cervix and assess the limited evidence for such immune recognition in the natural history of infection. CONCLUSION: the next generation of vaccination strategies should include the use of HPV 16 early (E2 and/or E6 and/or E7) and late gene targets (L1 and L2) expressed as VLPs with their clinical and immunological evaluation aimed at therapy as well as prophylaxis. Important clinical efficacy assessment may be deliverable in relatively short-term studies by targeting patients with HPV 16 associated vulval intraepithelial neoplasia.

An interstitial light assembly for photodynamic therapy in prostatic carcinoma.

OBJECTIVE: To develop an interstitial laser light delivery system using multiple optical fibres for photodynamic therapy (PDT) in the treatment of prostate cancer. PATIENTS AND METHODS: A laser beam was divided equally with a 1 x 4 fibre splitter to deliver PDT simultaneously through four 2-cm long, flexible cylindrical optical diffusers. Biplanar transrectal ultrasonography (TRUS) and a template were used to position the optical fibres percutaneously. In vivo measurements of light penetration depth (1/micro[eff] ) in prostate tissue were made in seven patients, using a sheathed isoprobe to measure light fluence rates at varying radial distances from the diffuser. The prostate was fixed with stabilization needles to minimize displacement during needle placement. RESULTS: The mean (sd, range) micro(eff) in the prostates of the seven patients was 0.35 (0.07, 0.22-0.44) mm-1, which produced closely parallel slopes of light attenuation. However, there was up to a 10-fold variation in absolute light levels at the same diffuser-detector separation distances amongst the seven patients, probably caused by blood pooling around the diffuser light source. A similar problem around the isoprobe detector was overcome by sheathing the probe in clear plastic tubing. By stabilizing the prostate, the optical fibre positioning was precise to within 2 mm. CONCLUSION: Although this light delivery and TRUS assembly were developed for clinical PDT in the prostate, the same instrumentation can be used reliably for in vivo light-penetration studies. Haemorrhage was unpredictable and highlighted one of the main problems which needs to be overcome.

Positron emission tomography of murine liver metastases and the effects of treatment by combretastatin A-4.

There are major potential advantages in non-invasive measurement of preclinical tumour biology and therapeutic response in clinically relevant, internal body sites, notably the ability to follow outcome in individual animals rather than averaging results from groups. We have exploited positron emission tomography (PET) to determine the feasibility of detecting liver metastases in B6D2F1 mice using fluorine-18 fluorodeoxyglucose ([18F]FDG) both before and after treatment by the novel cytotoxic agent, combretastatin A-4. The normal distribution of [18F]FDG in the absence of disease was characterised, with the clear delineation of the brain, the heart and the urinary bladder in all studies. In untreated mice with liver metastases, a strong correlation (r2 = 0.98) was found between the quantitative estimates of [18F]FDG uptake obtained by analysis of PET images, and those obtained from ex vivo assay of liver plus metastases excised immediately after imaging. In this first series, the effective limit of resolution was in livers containing a number of small metastases (range 8-14) with a single volume equivalent of approximately 200 mm3. PET image analysis was concordant with histological measurements in showing that single intraperitoneal doses of combretastatin A-4 resulted in an average 30% volume destruction of metastatic mass by 24 h following administration.