# Light as a Weapon: Redefining Cancer Care with Photodynamic Therapy

## TL;DR

This paper reviews how photodynamic therapy is becoming a more effective and versatile cancer treatment through new technologies and combinations with immunotherapy.

## Contribution

The paper highlights recent innovations in photosensitizer design, nanocarriers, and immunomodulatory effects of photodynamic therapy.

## Key findings

- New photosensitizers and nanocarriers improve tumor targeting and treatment depth.
- PDT is now being used as an immunomodulatory tool alongside immune checkpoint blockade.
- Challenges remain in standardization, safety, and clinical validation of PDT combinations.

## Abstract

Photodynamic therapy (PDT) has evolved over the past decade into a versatile cancer treatment modality, fueled by advances in photosensitizer design, nanotechnology, and immunotherapy. Smarter photosensitizers, ranging from activatable and oxygen-independent scaffolds to red/NIR-absorbing chromophores, have expanded tumor selectivity and tissue penetration. Nanocarrier-based delivery systems have improved solubility, biodistribution, and combinatorial theranostic potential, while innovative light sources such as upconversion nanoparticles, implantable LEDs, and X-ray-driven PDT are addressing penetration constraints. Importantly, PDT is no longer confined to local cytotoxicity but is increasingly recognized as an immunomodulatory platform capable of synergizing with immune checkpoint blockade (ICB) and in situ vaccination strategies. However, despite this progress, significant barriers remain, including poor standardization of dosimetry, heterogeneity in tumor hypoxia, unresolved safety concerns regarding nanocarriers, and limited clinical validation of combination regimens. This highlight review critically evaluates these advances and bottlenecks, outlining how PDT can realistically transition from a niche light-based therapy into a central component of precision oncology and next-generation immunotherapy.