Scott Carpenter4, Michael Cho4, Hon Cho4, Sebastian Marcuccio3, Donald Murphy4 & Daniel Garama1,2.
Prostate cancer is the most common form of internal cancer in Australian men, with 1 in 6 diagnosed before the age of 85 and 3000 men dying from the disease each year. Early detection and more informed treatments can significantly improve men’s prostate cancer survival and research is imperative to understanding this cancer and developing 21st century therapies for this disease. Photodynamic therapy (PDT) uses a combination of a photosensitiser (PS) and light of a specific wavelength, generating reactive oxygen species (ROS) on PS activation. We have developed a next generation PDT chlorin compound called INV043 and have shown that it has ~600 times greater phototoxicity than Talaporfin sodium, a widely used FDA approved, photosensitiser. We utilised INV043 to treat prostate cancer patients in a phase II clinical trial where patients underwent 12 cycles of PDT over 9 weeks. During each cycle, INV043 was given sublingually followed by exposure to trans-rectal laser therapy for 25 minutes at 4-hour intervals over 16 hours. We observed during the trial that INV043 was safe and well tolerated, with normal blood pressure, arterial pulse and oxygen levels observed during the therapy. Three months post treatment revealed ~44% of patients showed a positive response to treatment when evaluated by PSMA PET scan. This response rate combined with the minimal side effect and non-invasive administration makes our new generation chlorin based PDT particularly promising as a monotherapy, with the flexibility of further rounds of treatment or combination with other therapies.