Water-soluble phthalocyanine photosensitizers for photodynamic therapy

Cell-Penetrating Peptide Like Anti-Programmed Cell Death-Ligand 1 Peptide Conjugate-Based Self-Assembled Nanoparticles for Immunogenic Photodynamic Therapy

The tumor-specific efficacy of the most current anticancer therapeutic agents, including antibody-drug conjugates (ADCs), oligonucleotides, and photosensitizers, is constrained by limitations such as poor cell penetration and low drug delivery. In this study, we addressed these challenges by developing, a positively charged, amphiphilic Chlorin e6 (Ce6)-conjugated, cell-penetrating anti-PD-L1 peptide nanomedicine (CPPD1) with enhanced cell and tissue permeability. The CPPD1 molecule, a bioconjugate of a hydrophobic photosensitizer and strongly positively charged programmed cell death-ligand 1 (PD-L1) binding cell-penetrating peptide (CPP), is capable of self-assembling into nanoparticles with an average size of 199 nm in aqueous solution without the need for any carriers. These carrier-free nanoparticles possess the ability to penetrate the cell membrane of cancer cells and target tumors expressing PD-L1 on their surface. Notably, CPPD1 nanoparticles effectively blocked programmed cell death-1 (PD-1)/PD-L1 interactions and reduced PD-L1 expression via lysosomal degradation. They also demonstrated the responsiveness of CPPD1 nanoparticles in photodynamic therapy (PDT) to a 635 nm laser, leading to the generation of ROS, and induction of various immunogenic cell deaths (ICD). Highly penetrating CPPD1 nanoparticles could immunogenically modulate the microenvironment of CT26 cancer and were also effective in treating abscopal metastatic tumors, addressing major limitations of traditional PDT.

Silicon Phthalocyanines Functionalized with Axial Substituents Targeting PSMA: Synthesis and Preliminary Assessment of Their Potential for PhotoDynamic Therapy of Prostate Cancer

Photodynamic therapy (PDT) is a clinical modality based on the irradiation of different diseases, mostly tumours, with light following the selective uptake of a photosensitiser by the pathological tissue. In this study, two new silicon(IV)phtalocyanines (SiPcs) functionalized at both axial positions with a PSMA inhibitor are reported as candidate photosensitizers for PDT of prostate cancer, namely compounds SiPc-PQ(PSMAi)2 and SiPc-OSi(PSMAi)2. These compounds share the same PSMA-binding motif, but differ in the linker that connects the inhibitor moiety to the Si(IV) atom: an alkoxy (Si-O-C) bond for SiPc-PQ(PSMAi)2, and a silyloxy (Si-O-Si) bond for SiPc-OSi(PSMAi)2. Both compounds were synthesized by a facile synthetic route and fully characterized by 2D NMR, mass spectrometry and absorption/fluorescence spectrophotometry. The PDT agents showed a suitable solubility in water, where they essentially exist in monomeric form. SiPc-PQ(PSMAi)2 showed a higher singlet oxygen quantum yield ΦΔ, higher fluorescence quantum yields ΦF and better photostability than SiPc-OSi(PSMAi)2. Both compounds were efficiently taken up by PSMA(+) PC3-PIP cells, but not by PSMA(-) PC3-FLU cells. However, SiPc-PQ(PSMAi)2 showed a more specific photoinduced cytotoxicity in vitro, which is likely attributable to a better stability of its water solutions.