Findings From the PEACE-1 Trial in mCRPC

Cedric Pobel, MD, medical oncologist, PhD student, Institut de Cancérologie, Gustave Roussy, Paris, France, discusses recent findings from the PEACE-1 trial (NCT01957436) of radiotherapy plus standard of care and abiraterone in patients with low-volume metastatic castration-sensitive prostate cancer.

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0:10 | We had 400 patients with immunohistochemistry data and around 190 patients with next-generation sequencing data. The patient characteristics were similar across cohorts. In terms of phenotypic data, we observed 2 outliers in overall survival: one group with double-negative tumors, but this included only 3 patients, so it is difficult to draw conclusions from them.

0:47 | At the lower end of the survival curve, we found a neuroendocrine phenotype with a negative and positive neuron marker, which had a clearly shorter overall survival. However, this group had only 5 patients, so interpretation is again limited. The majority of patients were in the AR-high or AR-low tumor categories, and their overall survival was similar. [In contrast], the amphicrine patients had a slightly shorter overall survival.

1:17 | When we analyzed the data based on each protein expression, we found that 10 patients with a negative tumor had significantly worse outcomes. Similarly, patients with synaptophysin-positive and chromogranin-positive tumors also had a worse prognosis. Surprisingly, around 25% of patients had at least one neuroendocrine marker among synaptophysin, CD56, and chromogranin A, and these patients had the worst prognosis as well. It is important to note that, despite these findings, no biomarker was found to be predictive of abiraterone benefit in these patients.

2:12 | When we looked at the genomic data, we observed a similar number of alterations to what has been previously described in [patients with] metastatic castration-sensitive prostate cancer. There were only a few alterations in DNA repair genes, as expected in this castration-sensitive setting. Patients with at least 2 alterations in genes like TP53 and PTEN had shorter overall survival, but this subgroup only included 9 patients, so the interpretation remains limited.