Metastasis-Free Survival Predictive of Overall Survival in nmCRPC

Chicago—Clinical decisions as well as drug development for prostate cancer are facilitated with intermediate clinical end points. The international intermediate Clinical Endpoints in Cancer of the Prostate (ICECaP) working group reported that metastasis-free survival is a strong surrogate of overall survival in hormone-sensitive localized prostate cancer. Matthew Raymond Smith, MD, and colleagues conducted a study to examine the relationship between metastasis-free survival and overall survival in patients with nonmetastatic castration-resistant prostate cancer (nmCRPC).

Results of the analysis were reported during a poster session at the ASCO 2018 Annual Meeting in a poster titled Association of Metastasis-Free Survival (MFS) and Overall Survival (OS) in Nonmetastatic Castration-Resistant Prostate Cancer (nmCRPC).

The researchers utilized data from the phase 3 SPARTAN trial in men with high-risk nmCRPC. Following adjustments for covariates, a Cox proportional hazard regression model was used to evaluate the relationship of overall survival and the development of metastases. Spearman’s and Fleisher’s correlation statistics were used to assess the correlation of metastasis-free survival and overall survival.

Median time to metastasis among 1207 patients with nmCRPC as of May 2017 was 40.5 months. Compared with patients without metastasis, those who developed metastasis at 6, 9, and 12 months had significantly shorter median overall survival. Following adjustment for baseline covariates, the association between the development of metastases and overall survival remained.

There was a significant positive correlation between metastasis-free survival and overall survival (Spearman’s correlation coefficient, 0.62; P<.0001). The parametric Fleisher’s statistical model confirmed the positive correlation (correlation coefficient, 0.69), with ~50% of variability in overall survival explained by metastasis-free survival.

In conclusion, the researchers said, “Metastasis-free survival has a significant association with overall survival and is predictive of overall survival in high-risk nmCRPC. This analysis demonstrates that metastasis-free survival is a meaningful and valid intermediate clinical end point for overall survival.”

Clinical trial information: NCT01946204

Source: Smith MR, Mehra M, Nair S, Lawson J, Small EJ. Association of metastasis-free survival (MFS) and overall survival (OS) in nonmetastatic castration-resistant prostate cancer (nmCRPC). Abstract of a poster presented at the American Society of Clinical Oncology 2018 Annual Meeting, June 2, 2018, Chicago, Illinois.