Evaluation of Trastuzumab in Combination With Lapatinib or Pertuzumab in Combination With Trastuzumab-Emtansine to Treat Patients With HER2-positive Metastatic Colorectal Cancer

Investigators identified HER2 amplification as a potential onco-driver and marker of de novo resistance to anti-EGFR therapy in mCRC patients for which other known genetic alterations conferring resistance to anti EGFR antibodies were excluded. Exploiting direct transfer xenografts of mCRC surgical samples in mice (xenopatients), investigators conducted a multi-arm study in HER2-amplified xenopatients showing that combinations of the dual EGFR/HER2 inhibitor lapatinib and the anti-HER2 moAb trastuzumab induced long-lasting tumor regressions, while monotherapy with lapatinib led to stabilization and monotherapy with trastuzumab was ineffective. On these findings investigators designed the HERACLES trial. HERACLES is an open-label Phase II, 2-sequential cohorts trial, assessing the response rate (ORR) of Trastuzumab combined Lapatinib (Cohort A) or Pertuzumab combined with trastuzumab-emtansine (Cohort B), in metastatic colorectal patients harboring an amplified HER2 tumors . HER2 positivity is centrally established by immunohistochemistry (IHC) and Silver In Situ Hybridization (SISH). To be HER2 eligible the original tumor, or the biopsied metastasis (whichever is last available), must be IHC 3+ or 2+ in more than 50% of cells, confirmed by SISH or FISH with a HER2:CEP17 ratio ≥ 2.0. For IHC a positive staining (3+) is defined as an intense membrane staining which can be circumferential, basolateral, or lateral of the tumor cells.