There is evidence to support HER based therapy from the phase II HERACLES-A study that used meticulous biomarker selection of patients with HER2-amplified colorectal cancer, who typically do not respond well to conventional treatment options A two-pronged strategy, with lapatinib and trastuzumab yielded positive results in this subset of patients.
Lapatinib plus trastuzumab is a potential new treatment option for treatment-refractory HER2-positive colorectal cancer. seven trials: two diagnostic, three therapeutic (HERACLES-A, HERACLES-B, and HERACLES RESCUE), and two translational studies. HERACLES-B is evaluating pertuzumab (Perjeta) and ado-trastuzumab emtansine (also known as T-DM1 [Kadcyla]), and HERACLES RESCUE is looking at ado-trastuzumab emtansine monotherapy in metastatic colorectal cancer that has progressed on lapatinib and trastuzumab in HERACLES-A. IT is specifically the combined treatment that showed efficacy.
These studies need to be completed and published before one can conclude that this combined treatment is medically necessary.
.Siena S, Sartore-Bianchi A, Trusolino L, et al: Final results of the HERACLES trial in HER2-amplified colorectal cancer. 2017 AACR Annual Meeting. Abstract CT005. Presented April 2, 2017.
S. Siena et al, Targeting the human epidermal growth factor receptor 2 (HER2) oncogene in colorectal cancer. Ann Oncol 2018 May; 29(5): 11081119