Background: Patients with centrally located early lung cancer (CLELC) are often heavy smokers with a considerably high risk of multiple lung cancer (MPLC) lesions; treatment strategies for such patients must preserve the cardiopulmonary function.
Methods: Between June 2013 and June 2018, 10 patients with CLELC underwent photodynamic therapy (PDT) using NPe6, second-generation photosensitizer at Nippon Medical School Hospital. Among these patients, we retrospectively analyzed MPLC which were treated by surgery plus PDT or PDT alone, and examined the effectiveness of PDT and we propose a treatment strategy for patients with MPLC.
Results: Eight patients underwent surgery (five lobectomies and three partial resections) for primary lung cancer and then underwent NPe6-PDT for the treatment of secondary primary CLELC, two patients were performed PDT alone.
In 6 of these 10 patients, CLELC was found as metachronous lesions and in 4 patients as synchronous lesions using sputum cytology and a bronchoscopical examination using autofluorescence bronchoscopy.
All 10 lesions were CLELC and identified by autofluorescence bronchoscopy. Among the 10 patients with MPLC including peripheral-type lung cancers which were resected by surgery, all 10 CLELC lesions exhibited a complete response after PDT.
Conclusions: For lung cancer patients with a long-term history of smoking, careful follow-up examinations after surgical resection are needed considering the incidence of metachronous primary lung cancers. PDT can play an important role for the treatment strategy for MPLC.
The report of patients with lung cancer who could receive PDT combined with other modalities like surgery and chemotherapy is relatively rare. Combination of PDT and surgery is useful for multiple lung cancers (MPLC) or minimally invasive procedure to reduce resection line to peripheral site of superficial invasion in advanced lung cancer. Also, PDT combined with chemotherapy for advanced lung cancer with central airway stenosis seems to be usefull for local control and improvement of patient’s QOL.
MPLCs were noted in 22 (34.4%) of 64 patients treated with PDT using Laserphyrin (synchronous:10, and metachronous: 12). Among them, 10 patients (synch:2, meta:8) underwent surgery (lobectomy: 9, pneumonectomy: 1) for peripheral-type lung cancer as their first primary lesion followed by PDT for central type early stage lung cancer. CRs were achieved after PDT in all patients, and all patients were alive. We performed induction PDT to reduce resection line for 28 patents. Among them, histological type revealed squamous cell ca. in 24. Superficial invasion was recognized in trachea: 2, carina: 3, main bronchus or 2nd carina: 22. Reduction surgery could be successfully performed in 23 of 28 patients (82%). PDT combined with chemotherapy was performed for 12 consecutive patients with 13 advanced NSCLC whose stages were IIIA–IV. The median stenosis rates before treatment, 1 week, and 1 month after treatment were 60%, 15%, and 15%, respectively. All patients improved symptoms and QOL after treatment. The mean survival time was 5.9 months, and the overall one-year survival rate was 30.0%.PDT combined with other modalities may be a promising strategy in lung cancer treatment.
Background: Skin photosensitivity is a major side effect of photodynamic therapy (PDT). It is induced by the photosensitizer remaining in the skin. It is usually rapidly metabolized by the liver, but the pharmacokinetic profile varies widely among individuals. This makes it difficult to predict the incidence of skin photosensitivity. Therefore, we conducted a prospective study to investigate whether the NPe6 fluorescence intensity in skin after NPe6-PDT could be measured safely in human patients using a fluorescence sensing system for judging the risk of skin photosensitivity.
Methods: The NPe6 fluorescence measurements using a constructed fluorescence sensing system at the inside of the arm were acquired prior to and 5 and 10 minutes after NPe6 administration as well as at the time of PDT (4-5 hours after administration), at discharge (2 or 3 days after PDT), and at 1 or 2 weeks after PDT. Participants were interviewed as to whether they had any complications at 2 weeks after PDT.
Results: Nine male patients and one female patient entered this study. All of the measurements of NPe6 fluorescence in the skin could be obtained without any complications. The spectral peak was detected at the time of discharge (2-3 days after administration) in most cases and it decreased at 1 or 2 weeks after PDT.
Conclusions: The fluorescence of NPe6 in the skin could be detected feasibly using the fluorescence sensing system in human patients. Measuring fluorescence intensity in the skin might be useful to predict the incidence of skin photosensitivity after PDT.
We studied a 3-compartment dynamic model of talaporfin sodium pharmacokinetics in silico. Drug distribution might
change after intravenous injection from plasma to interstitial space and then into myocardial cells. We have developed a
new cardiac ablation using photosensitization reaction with laser irradiation shortly after talaporfin sodium injection. We
think that the major cell-killing factor in our cardiac ablation would be an oxidation by singlet oxygen produced in the
interstitial space in myocardium with laser irradiation shortly after the photosensitizer administration. So that the
talaporfin sodium concentration change in time in the interstitial space should be investigated. We constructed the
pharmacokinetics dynamic model composed by 3-compartments, that is, plasma, interstitial space, and cell. We
measured talaporfin sodium fluorescence time change in human skin by our developed fluorescence measurement system
in vivo. Using the measured concentration data in plasma and skin in human, we verified the calculation accuracy of our
in silico model. We compared the simulated transition tendency of talaporfin sodium concentration from interstitial space
to cells in our in silico model with the reported uptake tendency using cultured myocardial cell. We identified the
transition coefficients between plasma, interstitial space, and cell compartment, and metabolization coefficient from
plasma by the fitting with measured data.
Expression of the anti-apoptotic proteins Bcl-2 and/or Bcl-xL is greatly elevated in many advanced cancers, especially those resistant to standard therapies, such as radiation or chemotherapy. It has been suggested that those two proteins would be attractive targets for the development of new cancer treatments. Photodynamic therapy (PDT) with photosensitizers that localize in or target mitochondria, such as the phthalocyanine Pc 4, specifically attack the anti-apoptotic protein Bcl-2, generating a variety of oxidized, complexed, and cleaved photoproducts. The closely related protein Bcl-xL is also a target of Pc 4-PDT. In a recent study employing transient transfection of an expression vector encoding deletion mutants of Bcl-2, we identified the membrane anchorage regions of the protein that are required to form the photosensitive target. In spite of the demonstrated photodamage to Bcl-2 (and Bcl-xL), how the photodamage translates into changes in the sensitivity of cells to PDT-induced apoptosis or other modes of cell death is not clear, and it also remains unclear how elevated amounts of anti-apoptotic proteins in tumors might make them more or less responsive to PDT. In the present study, we have studied the PDT response of MCF7 human breast cancer cells overexpressing wild-type Bcl-2 or certain deletion mutants either in a transient or stable mode. We show that cells expressing modestly elevated amounts (<10-fold increase) of Bcl-2 and in which the pro-apoptotic protein Bax is not upregulated do not differ from the parental cells with respect to PDT-induced cell killing. In contrast, cells expressing higher amounts (>50-fold increase) of Bcl-2 or certain mutants are made significantly more resistant to the induction of apoptosis and the loss of clonogenicity upon exposure to Pc 4-PDT. In the presence of high levels of Bcl-2, extensive photodamage requires higher PDT doses. We conclude that Pc 4-PDT targets Bcl-2 and Bcl-xL, eliminating one mechanism that protects the tumor cells from other types of therapy. However, it is possible that cells expressing very high levels of the anti-apoptotic proteins might still be resistant to PDT. The data suggest that PDT with a non-vascular-targeting photosensitizer might be effective in a combination treatment in which Bcl-2 and Bcl-xL are first photodamaged before delivery of a second agent.
In response to photodynamic therapy (PDT), many cells in culture or within experimental tumors are eliminated by apoptosis. PDT with photosensitizers that localize in or target mitochondria, such as the phthalocyanine Pc 4, causes prompt release of cytochrome c into the cytoplasm and activation of caspases-9 and -3, among other caspases, that are responsible for initiating cell degradation. Some cells appear resistant to apoptosis after PDT; however, if they have sustained sufficient damage, they will die by a necrotic process or through a different apoptotic pathway. In the case of PDT, the distinction between apoptosis and necrosis may be less important than the mechanism that triggers both processes, since critical lethal damage appears to occur during treatment and does not require the major steps in apoptosis to be expressed. We earlier showed, for example, that human breast cancer MCF-7 cells that lack caspase-3 are resistant to the induction of apoptosis by PDT, but are just as sensitive to the loss of clonogenicity as MCF-7 cells stably expressing transfected procaspase-3. Many photosensitizers that target mitochondria specifically attack the anti-apoptotic protein Bcl-2, generating a variety of crosslinked and cleaved photoproducts. Recent evidence suggests that the closely related protein Bcl-xL is also a target of Pc 4-PDT. Transient transfection of an expression vector encoding deletion mutants of Bcl-2 have identified the critical sensitive site in the protein that is required for photodamage. This region contains two alpha helices that form a secondary membrane anchorage site and are thought to be responsible for pore formation by Bcl-2. As specific protein targets are identified, we are becoming better able to model the critical events in PDT-induced cell death.
The effectiveness of a new excimer laser endoscopic imaging fluorescence analyzer system using the photosensitizer, mono-L-aspartyl chlorin e6 (NPe6) for the detection of tumors was evaluated. Autofluorescence (550 plus or minus 10 nm, green fluorescence) from normal sites, red fluorescence (664 nm) of NPe6 in areas of cancer and the red fluorescence/green fluorescence ratio (R/G ratio) as the color image can be detected respectively. The greatest NPe6 fluorescence from the lesion was obtained at 3 hours after injection and the fluorescence disappeared at 24 hours. The greatest difference in the fluorescence of NPe6 and the R/G ratio in areas of tumor and in normal areas were observed at 5 hours after administration. At this period, NPe6 fluorescence from normal sites was negligible. These data suggest that fluorescence photodiagnosis may be effective in the detection of cancers.
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