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In this article, we introduce our recent clinical trials of PDT for lung cancers (both central and peripheral), and new techniques of PDD in sentinel node navigation biopsy for breast cancers. Moreover, we introduce basic research on cancers and infectious diseases in order to expand the clinical applications of PDT.

Abstract. ATX-s10 is a novel and second-generation photosensitizer for photodynamic therapy (PDT). In order to conduct clinical trials of ATX-s10-PDT and/or extend its clinical applications, it is very important to elucidate the mechanisms of the action of ATX-s10-PDT. We examined the apoptic response against ATX-s10-PDT using a Bcl-2 or Bcl-2 mutant overexpressing cells. Using fluorescent microscopy, ATX-s10 localized not only to mitochondria but also to lysosomes and possibly other intracellular organelles, but not to the plasma membrane or the nucleus. These results suggest that ATXs10-PDT can damage mitochondria and lysosomes. By Western blot analysis, ATX-s10-PDT damaged Bcl-2, which localized preferentially at mitochondrial membranes, and caused Bcl-2 to cross-link immediately after laser irradiation. However, ATX-s10-PDT was not able to rapidly induce morphologically typical apoptosis (i.e. chromatin condensation and fragmentation) as PDT using mitochondria targeted photosensitizers, such as phthalocyanine 4 (Pc 4). Pharmacological inhibitions of lysosomal cytokine protease cathepsins, such as cathepsin B and D, protected MCF-7c3 cells (human breast cancer cells expressing stably transfected procaspase-3) from apoptosis caused by ATX-s10-PDT. Overexpression of wildtype Bcl-2 or Bcl-2Δ33-54 resulted in relative resistance of cells to ATX-s10-PDT, as assessed by the degree of morphological apoptosis or loss of clonogenicity. We conclude that lysosomal damage by ATX-s10-PDT can initiate apoptotic response and this apoptotic pathway can be regulated by photodamage to Bcl-2 via mitochondrial damage.

Weekly administration of nanoparticle albumin‐bound paclitaxel (nab‐paclitaxel) has been shown to be a safe and effective treatment for metastatic breast cancer (MBC) in clinical studies. We conducted a multicenter, randomized, open‐label phase II study to compare the efficacy and safety of weekly nab‐paclitaxel and docetaxel in Japanese patients with human epidermal growth factor receptor 2‐negative MBC. The primary endpoint was progression‐free survival (PFS). Patients were randomized to receive nab‐paclitaxel (150 mg/m2 nab‐paclitaxel once per week for 3 of 4 weeks; n = 100) or docetaxel (75 mg/m2 docetaxel every 3 weeks; n = 100). The median PFS by independent radiologist assessment was 9.8 months (90% confidence interval [CI]: 8.5–11.2) for nab‐paclitaxel and 11.2 months (90% CI: 8.4–13.8) for docetaxel (hazard ratio: 1.25, P = 0.363), and the median overall survival was 42.4 months and 34.0 months, respectively. The overall response rate was 56.1% for nab‐paclitaxel and 52.5% for docetaxel. Adverse events in both treatment arms were similar to previous reports. Neutropenia was the most common adverse event in both arms, with 35.0% of patients in the nab‐paclitaxel arm and 89.0% in the docetaxel arm experiencing grade 4 neutropenia. Grade 3 peripheral sensory neuropathy occurred in 22.0% of patients in the nab‐paclitaxel and 5.0% in the docetaxel arm. In this study, although weekly nab‐paclitaxel 150 mg/m2 did not show superiority in PFS compared with docetaxel, efficacy outcomes were similar in patients treated with weekly nab‐paclitaxel and docetaxel.