The SPARTAN study – the treatment of non-metastatic castration-resistant prostate cancer

Eric J. Small | Aug 2020 | ASCO20 Virtual | Onkologi / Hematologi |

Eric J. Small
Professor of Medicine and Urology,
Deputy Director and
Chief Scientific Officer,
UCSF Helen Diller
Family Comprehensive Cancer Center
University of California, San Francisco

At ASCO 2020 meeting, the new final survival results of the SPARTAN study were reported. When we look at overall survival in SPARTAN, the use of apalutamideprolongs survival from 60 months to 74 months – that is a 14-month survival advantage, with a hazard ratioof 0.78. Earlier reports have shown significant advantages in reduction of metastasis development rates and the time to symptomatic regression. Castration-resistant prostate cancer (CRPC) was until fairly recently not recognized as a serious disease, simply because metastasis formation could not be observed. We know now that CRPC is a potentially very lethal disease: it is estimated that about 45% of CRPC patients will either develop a metastasis or die within two years. Among patients with very rapid prostate-specific antigen (PSA) doubling times, the number increases to 60% or 70%. Currently there is increasing interest in non-metastatic CRPC. This is partly due to the enormous unmet need: it was only recently realized that we should be concerned about this group of patients. The increasing interest also reflects the natural evolution of the use of the second generation or next generation androgen receptor signaling inhibitors. We had already seen abiraterone, enzalutamide and apalutamide benefiting patients with metastatic CRPC. The question in oncology is always: if it works in patients with very extensive disease, will it work in less extensive cases? SPARTAN study design The SPARTAN study was a phase 3, randomized, registrational, double-blind, placebo-controlled, multicenter study. One of the significant advances in the SPARTAN study design was the ability to select patients appropriately. Selection was based on the observation that the PSA doubling time is very helpful in predicting the likelihood of metastasis. There is an inflection point around the eight to ten-month mark, at which the risk rises rapidly. Therefore, the SPARTAN study restricted entry to patients...