Multi-Omic Profiling Of Metastatic Lesions To Guide Treatment Selection: The Side Out 2 Trial Experience.

1077Background: The aim of this prospective pilot study, the Side Out 2 trial (NCT01919749), was to explore if treatment selection based on Multi-omic Profiling (MoP) provides clinical benefits superior to empiric treatment selection in progressive metastatic breast cancers (MBC). Methods: Fresh core biopsies were collected from the metastatic lesions of 32 MBC patients. Samples underwent genomic and proteomic profiling, including: exome sequencing, RNA-Seq, IHC, and quantitative phosphoprotein-based protein pathway activation mapping by Reverse Phase Protein Microarray (RPPA). Whole tissue lysates were used for the exome sequencing, RNA-Seq and IHC; the RPPA data were obtained from microdissected tumor epithelia. A sample size of 25 evaluable patients was determined a priori according to the exact single-stage design for phase II studies, using a type I error rate of 5% (one-sided) and a power of 90%. Clinical benefit was defined as Growth Modulation Index (GMI) ≥ 1.3 assuming that MoP selected therapy w...