Chemophototherapy: An Emerging Treatment Option for Solid Tumors

Near infrared (NIR) light penetrates human tissues with limited depth, thereby providing a method to safely deliver non‐ionizing radiation to well‐defined target tissue volumes. Light‐based therapies including photodynamic therapy (PDT) and laser‐induced thermal therapy have been validated clinically for curative and palliative treatment of solid tumors. However, these monotherapies can suffer from incomplete tumor killing and have not displaced existing ablative modalities. The combination of phototherapy and chemotherapy (chemophototherapy, CPT), when carefully planned, has been shown to be an effective tumor treatment option preclinically and clinically. Chemotherapy can enhance the efficacy of PDT by targeting surviving cancer cells or by inhibiting regrowth of damaged tumor blood vessels. Alternatively, PDT‐mediated vascular permeabilization has been shown to enhance the deposition of nanoparticulate drugs into tumors for enhanced accumulation and efficacy. Integrated nanoparticles have been reported that combine photosensitizers and drugs into a single agent. More recently, light‐activated nanoparticles have been developed that release their payload in response to light irradiation to achieve improved drug bioavailability with superior efficacy. CPT can potently eradicate tumors with precise spatial control, and further clinical testing is warranted. Combining chemotherapy and phototherapy (chemophototherapy, CPT) is a potent, complex, and underutilized strategy to treat solid tumors. This review summarizes the current state of CPT, from preclinical to clinical studies. The growing emphasis on nanocarrier‐enabled CPT is discussed.