Year of Grant: 2016

Location: Switzerland

Prostate cancer is the most common cancer in men, with one dying from the disease every hour. On average, 90,000 men in Europe die from the disease each year. Surgery is one of the main curative options for prostate cancer, however more than 35% of all men with prostate cancer treated with surgery will not be cured. As the cancer can invade the bones and lymph nodes (metastases), many patients will suffer and die as a result of the cancer spreading.

Local radiotherapy (salvage radiotherapy) is currently the standard treatment for patients presenting increased prostate specific antigen (PSA) after surgery with no detectable disease in the bones or lymph nodes. Despite the use of salvage radiotherapy, about 40% of the patients still experience poor results.

Metformin, a repurposed anti-diabetic drug, has been undergoing investigation as a potential treatment for different cancers in numerous studies, and has shown to improve the efficacy of local radiation treatment in studies with tumor cells, animals and retrospective studies with humans. It appears well tolerated, presents minimal side effects and is relatively inexpensive. While metformin has also shown to improve results of prostate cancer treatments in many large retrospective studies, its definite role still needs to be further investigated in prospective studies.

This new phase II clinical trial seeks to test salvage radiotherapy with metformin or placebo in patients with non-metastatic prostate cancer after prostatectomy failure. It is hypothesized that this novel treatment combination can slow prostate cancer related mortality. Over a period of 12 months, a total of 170 patients (100 in Switzerland) will be randomized either to radiotherapy plus metformin or placebo. All patients will be followed up for a maximum of 10 years.

The primary aim is to determine whether the radiotherapy plus metformin is superior to the standard of care after prostatectomy failure. Several trial-associated translational studies will also be conducted to better explain metformin’s mechanism of action and identify predictive biomarkers for metformin treatment. In this regard, this study will be one of the main pillars advancing the current standard of care towards a well-known, safe and affordable medication.