Application of lower fluence rate for less microvasculature damage and greater cell-killing during photodynamic therapy

Novel Water-Soluble Chlorin-Based Photosensitizer for Low-Fluence Photodynamic Therapy

Photodynamic therapy (PDT), performed with low-fluence rates, can improve antitumor responses and prevent adverse effects. However, photosensitizers (PSs) for low-fluence PDT treatment are rarely reported. Herein, we exploited an amphiphilic chlorin-based PS, named DYSP-C34, which has a variety of beneficial biological properties, such as improved water solubility, better cellular permeability, specific localization and enhanced phototoxicity under low light dose irradiation. In addition, DYSP-C34 could effectively accumulate in a mouse subcutaneous xenograft tumor and exhibit substantial tumor regression after irradiation with an extremely low light fluence (6 J/cm²). Meanwhile, the excellent phototoxicity could stimulate the host immune system and lead to a strong inhibition of tumor growth synergistically. These results indicated the potential value of DYSP-C34 as a chlorin-type PS for low-fluence PDT application.

[Low-fluence photodynamic therapy in chronic central serous chorioretinopathy]

OBJECTIVE

To evaluate safety and efficacy of low-fluence photodynamic therapy (LFPDT) with verteporfin in patients affected with chronic central serous chorioretinopathy (CCSC), in terms of visual acuity (VA) and macular morphology measured with optical coherence tomography (OCT).

METHODS

A retrospective, non-randomized and interventionist analysis was performed on 16 eyes in 15 patients with CCSC treated with LFPDT. Best corrected visual acuity (BCVA) with ETDRS optotypes and central foveal thickness (CFT) in OCT were evaluated as outcome measures.

RESULTS

The mean follow-up was 10.8 months. The mean BCVA improved from 58.12 to 68.68 ETDRS letters, and CFT decreased from 280.5 to 172.18 microns, with subretinal fluid resolution in 14 eyes (87.5%), two of them after a second LFTPD. No complications related to treatment were recorded.

CONCLUSIONS

LFPDT with verteporfin can be useful in CCSC to stabilise or improve BCVA, reabsorb subretinal fluid and reduce CFT. Randomised studies with a longer follow-up are required to assure the role of this treatment and to optimise parameters for higher efficacy and safety in CCSC patients.