A randomised trial of oral sodium clodronate versus a matching placebo in patients with metastatic prostate adenocarcinoma.
Can the drug clodronate delay further development of prostate cancer once it has spread to the bones?
What was this study about?
PR05 was a trial for men who were within 3 years after initial diagnosis with prostate cancer with bone metastases. The aim of this trial was to see whether addition to the standard therapy of a first general bisphosphonate drug called sodium clodronate (Loron520) could delay or prevent the progression of symptomatic bone metastases. Consenting patients were therefore randomly assigned to receive either daily oral sodium clodronate or placebo for a maximum of 3 years.
What difference did this study make?
We found that clodronate had some helpful effects. We found some good evidence that the risk of bone metastases that caused symptoms like pain was reduced with clodronate. We also found that some men lived longer with clodronate, but we cannot prove this conclusively.
Many men did not find their study tablets easy to take. More men taking clodronate stopped taking their tablets earlier than the men who took the placebo. Many men reported side-effects, but few of these were serious and none were life-threatening. These side-effects usually stopped when the men took fewer tablets or when the tablets were stopped. The most common side-effects were gastro-intestinal problems. These were more common in men who took clodronate - 31 men of the 156 men who took clodronate reported gastro-intestinal problems. So did 21 men of the 155 men who took the placebo.
This shows us the value of the placebo tablets: if, instead of taking placebo tablets, men in the control group were taking nothing, they may not have mentioned the stomach upsets (or other adverse events) to their study doctor. Then, in the analyses, the side-effects thought to be from clodronate would have appeared much worse than they actually were. We believe that this is an extremely important finding which is highly relevant to other, future trials.
This trial helped doctors to be confident that bisphosphonates should be investigated further for men with prostate cancer who have bone metastases. The STAMPEDE trial is looking at a newer, stronger bisphosphonate drug.
Type of study
Who funded the study?
Medical Research Council with support from Roche Products Ltd (formerly Boehringer Mannheim [UK])
When did it take place?
Patients were recruited between 1994 and 1997.
Where did it take place?
Hospitals throughout the UK and New Zealand.
Who was included?
Men with metastatic prostate cancer.