The sustaining of fluorescence in photodynamic diagnosis after the administration of 5-aminolevulinic acid in carcinogen-induced bladder cancer orthotopic rat model and urothelial cancer cell lines

Location-specific diagnostic efficiency of photodynamic diagnosis-guided biopsy in bladder mapping biopsies

BACKGROUND

Photodynamic diagnosis (PDD)-assisted transurethral resection of bladder tumors (TURBT) has emerged as a promising complementary tool to white light (WL) cystoscopy, potentially improving cancer detection and replacing conventional mapping biopsies. This study aimed to investigate the diagnostic accuracy of PDD by anatomical locations in mapping biopsies through lesion-based analysis.

METHODS

PDD and WL findings were prospectively recorded in 102 patients undergoing mapping biopsies and PDD-assisted TURBT using oral 5-aminolevulinic acid. We evaluated 673 specimens collected from flat tumor or normal-looking lesions on WL cystoscopy, after excluding 98 specimens collected from papillary or nodular tumors.

RESULTS

Among the 673 lesions, cancer was detected in 110 (16%) by lesion-based analysis. PDD demonstrated significantly higher sensitivity (65.5% vs. 46.4%, p < 0.001) and negative predictive value (92.5% vs. 89.5%, p < 0.001) compared to WL. The sensitivity of PDD findings varied by location: posterior (100%), right (78.6%), dome (73.3%), left (70.6%), trigone (58.8%), bladder neck (41.7%), anterior (40.0%), and prostatic urethra (25.0%). Incorporating targeted biopsies of specific locations (bladder neck, anterior, and prostatic urethra) into the PDD-guided biopsies, regardless of PDD findings, significantly increased the overall sensitivity from 65.5% to 82.7% (p = 0.001).

CONCLUSIONS

This study first demonstrated the detection rate of location-specific mapping biopsies using PDD, revealing difficulties in accuracy assessment in areas susceptible to tangential fluorescence. While PDD-guided biopsy improves cancer detection compared to WL cystoscopy even for flat tumors or normal-looking lesions, more careful decisions, including mapping biopsies, may be beneficial for an assessment in these tangential areas.

Inflammatory cell death induced by 5-aminolevulinic acid-photodynamic therapy initiates anticancer immunity

Background

Inflammatory cell death is a form of programmed cell death (PCD) that induces inflammatory mediators during the process. The production of inflammatory mediators during cell death is beneficial in standard cancer therapies as it can break the immune silence in cancers and induce anticancer immunity. Photodynamic therapy (PDT) is a cancer therapy with photosensitizer molecules and light sources to destroy cancer cells, which is currently used for treating different types of cancers in clinical settings. In this study, we investigated if PDT using 5-aminolevulinic (5-ALA-PDT) causes inflammatory cell death and, subsequently, increases the immunogenicity of cancer cells.

Methods

Mouse breast cancer (4T1) and human colon cancer (DLD-1) cells were treated with 5-ALA for 4 hours and then irradiated with a light source. PCD induction was measured by western blot analysis and FACS. Morphological changes were determined by transmission electron microscopy (TEM). BALB/c mice were injected with cell-free media, supernatant of freeze/thaw cells or supernatant of PDT cells intramuscular every week for 4 weeks and then challenged with 4T1 cells at the right hind flank of BALB/c. Tumor growth was monitored for 12 days.

Results

We found that 5-ALA-PDT induces inflammatory cell death, but not apoptosis, in 4T1 cells and DLD-1 cells in vitro. Moreover, when mice were pretreated with 5-ALA-PDT culture supernatant, the growth of 4T1 tumors was significantly suppressed compared to those pretreated with freeze and thaw (F/T) 4T1 culture supernatant.

Conclusion

These results indicate that 5-ALA-PDT induces inflammatory cell death which promotes anticancer immunity in vivo.

Transurethral resection of bladder cancer with or without fluorescence

PURPOSE OF REVIEW

Transurethral resection of bladder cancer (TURBT) is in its standard form an inherently imperfect technique. Fluorescence-guided photodynamic diagnosis (PDD) represents one way to improve the outcome by enhancing tumour detection. Fluorescence has been used in connection with bladder cancer since the 1970s, with a number of studies being published since then. However, the method is still not recommended as a standard part of TURBT mainly because of the limited level of evidence of concerned studies, questionable cost-effectiveness and even contradictory results. The review lists the latest articles covering this topic.

RECENT FINDINGS

Several recently published meta-analyses reviewed a series of randomized controlled trials (RCTs) concerning PDD assisted TURBT. Results were generally supporting the positive effect on reduction of recurrence rate. However, the mentioned meta-analyses are overlapping in terms of reviewed RCT that provide only a low level of evidence according to a recent Cochrane review. Supposed limitations of PDD (timing of the procedure, low specificity) and possible solutions are also covered.

SUMMARY

Most of the published data confirmed reduced early recurrence rate after PDD assisted TURBT comparing to standard TURBT. Its impact on late recurrence rate, progression rate or cost-effectiveness has not been sufficiently demonstrated.

Fluorescence-Based Microendoscopic Sensing System for Minimally Invasive In Vivo Bladder Cancer Diagnosis

Bladder cancer is commonly diagnosed by evaluating the tissue morphology through cystoscopy, and tumor resection is used as the primary treatment approach. However, these methods are limited by lesion site specificity and resection margin, and can thereby fail to detect cancer lesions at early stages. Nevertheless, rapid diagnosis without biopsy may be possible through fluorescence sensing. Herein, we describe a minimally invasive imaging system capable of sensing even small tumors through a 1.2 mm diameter flexible fiber bundle microprobe. We demonstrate that this new device can be used for the early diagnosis of bladder cancer in rats. Bladder cancer was induced in rats using the carcinogen N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN), and a togglable filter capable of PpIX fluorescence sensing was installed in the microendoscopic system. Following 5-aminolevulinic acid administration, tissue in the early stages of bladder cancer was successfully identified with fluorescence detection and confirmed with hematoxylin/eosin and ferrochelatase staining. Although the time required for BBN to induce bladder cancer varied between 3 and 4 weeks among the rats, the microendoscopic system allowed the minimally invasive follow-up on cancer development.

Photodynamic Therapy for the Treatment and Diagnosis of Cancer-A Review of the Current Clinical Status

Photodynamic therapy (PDT) has been used as an anti-tumor treatment method for a long time and photosensitizers (PS) can be used in various types of tumors. Originally, light is an effective tool that has been used in the treatment of diseases for ages. The effects of combination of specific dyes with light illumination was demonstrated at the beginning of 20th century and novel PDT approaches have been developed ever since. Main strategies of current studies are to reduce off-target effects and improve pharmacokinetic properties. Given the high interest and vast literature about the topic, approval of PDT as the first drug/device combination by the FDA should come as no surprise. PDT consists of two stages of treatment, combining light energy with a PS in order to destruct tumor cells after activation by light. In general, PDT has fewer side effects and toxicity than chemotherapy and/or radiotherapy. In addition to the purpose of treatment, several types of PSs can be used for diagnostic purposes for tumors. Such approaches are called photodynamic diagnosis (PDD). In this Review, we provide a general overview of the clinical applications of PDT in cancer, including the diagnostic and therapeutic approaches. Assessment of PDT therapeutic efficacy in the clinic will be discussed, since identifying predictors to determine the response to treatment is crucial. In addition, examples of PDT in various types of tumors will be discussed. Furthermore, combination of PDT with other therapy modalities such as chemotherapy, radiotherapy, surgery and immunotherapy will be emphasized, since such approaches seem to be promising in terms of enhancing effectiveness against tumor. The combination of PDT with other treatments may yield better results than by single treatments. Moreover, the utilization of lower doses in a combination therapy setting may cause less side effects and better results than single therapy. A better understanding of the effectiveness of PDT in a combination setting in the clinic as well as the optimization of such complex multimodal treatments may expand the clinical applications of PDT.