Photodynamic therapy management of canine mammary gland tumour with wireless upconversion implant

In photodynamic therapy (PDT), efficacious tumour regression is attained through sufficient illumination intensity and frequency across photosensitised tumour area. An emerging tether‐free optical implantable is realised by shifting the excitation to tissue penetrating near‐infrared with upconversion nanoparticles (UCNPs). Despite advances in UCNP designs, the translation of UCNPs from bench to bedside is still limited to preclinical rodent cancer models. Here, we report three case studies of wireless PDT using high‐efficiency submicrometre UCNPs polydimethylsiloxane flexible implant on geriatric canine mammary gland tumours for more than a month till 15 months. Repetitive PDT led to tumour growth control in two out of three patients, in whom intervention was started early before tumour reached an aggressive size. The implant also did not restrict the mobility of patients. Our proof‐of‐concept study suggests early upconversion PDT is feasible, safe and effective even across canine skin, which recapitulates the human physique much more closely than rodents.