A novel multicentric European research study revealed non-surgical vascular-targeted photodynamic therapy employed in low-risk prostate cancer kills cancer cells while preserving normal tissue and has more effective safety and efficacy than active surveillance.
Generally, active surveillance that observes the progression of the abnormal growing cells of the prostate is an appropriate method adopted in low-risk prostate cancer, and the cancer is treated only when it becomes severe. Although active surveillance has demonstrated favourable outcomes, this approach has been associated limitations in terms of intervention rates. Most of the interventions or treatment procedures employed in prostate cancer involve tissue-preserving strategies. One such therapeutic approach is radical therapy, which involves removal or irradiating the prostate gland surgically, which has significant long-term side effects. The new vascular-targeted photodynamic therapy (VTP) involves injecting a light-sensitive drug (WST11, also known as padeliporfin) into the bloodstream and then activating it with a laser to destroy the tumour tissue in the prostate. The WST11 drug is derived from bacteria at the bottom of the ocean. It is able to survive with very little sunlight by converting light into energy with incredible efficiency. This mechanism was used to develop WST11, a compound that releases free radicals to kill surrounding cells, but only when activated by laser light. The findings of this research study on the non–surgical treatment of prostate cancer were published in the Lancet Oncology, 2016.
In order to understand the role of non-surgical therapy on prostate cancer, a phase 3 trial was conducted in 47 centres in 10 different European countries and consisted of 413 enrolled patients as study subjects. 206 patients were randomly subjected to focal therapy and 207 to active surveillance and the treatment was followed up for 24 months. Interestingly, disease progression was noticed in 28% of the vascular-targeted photodynamic therapy undergoing group compared to 58% in the active surveillance group. In addition, 49% of men in the vascular-targeted photodynamic therapy group had a negative prostate biopsy at 24 months of post-treatment when compared with 14% men in the active surveillance group. Therefore, vascular-targeted photodynamic therapy was effective in treating prostate cancer. Moreover, adverse events associated with therapeutic approaches followed in prostate cancer. One of the most common serious adverse events in the vascular-targeted photodynamic therapy group was retention of urine that was resolved within 2 months in all patients while the active surveillance group experienced an increase in myocardial infarctions.
In summary, nonsurgical padeliporfin vascular-targeted photodynamic therapy can be used widely in treating prostate cancer and is an effective treatment approach that is associated with safety. More research is required in addressing tissue-preserving treatments of prostate cancer and the efficacy of padeliporfin vascular-targeted photodynamic therapy in eradicating different grades of cancers.
Written By: Manche Santoshi, PhD