ASCO GU: Highlights on Non Metastatic Castration-resistant Prostate Cancer, the SPARTAN and PROSPER Trials

Speaker: Stéphane Oudard

Reporting from ASCO GU 2018, Stephane Oudard highlights two large randomised phase III studies relevant for clinical practice (SPARTAN with apalutamide and PROSPER with enzalutamide) in term of providing new treatment options for the group of patients with non-metastatic castration-resistant prostate cancer (CRPC) who are at high risk of developing metastasis.

The results from these two large randomised trials presented at ASCO GU are highly positive. Primary endpoint was metastasis-free survival (MFS) with outstanding outcome.

The SPARTAN trial showed a highly significant difference in median MFS (40 months with apalutamide vs 16 months for placebo). Although the secondary endpoints are positive and Quality of Life was good, side effects such as fractures, falls and rash were recorded. Further follow-up is needed to confirm the positive trend shown in term of progression-free survival.

The PROSPER trial also showed a highly significant difference in median MFS (36 months with enzalutamide vs 14 months for placebo). However the toxicity profile is quite different, hyponatremia and seizure have been reported but no rash. Occurrence of fractures haven't been studied specifically.

Stephane Oudard concludes that it is too early to know the results in term of overall survival. He questions if moving these drugs to earlier stage of the disease induce hormonal resistance that could reduce the response at potential relapse; looking at early vs late treatment would be interesting.

It would also be interesting to learn what the ideal schedule for imaging follow-up would be and if we should rely on PSA. The evolution of imaging techniques are making the detection of early metastasis easier and this group of patients may become smaller in the future.