1676P Active immunization with a multi-peptide B cell vaccine, targeting trastuzumab and pertuzumab binding sites, prevents the formation of HER-2/neu expressing lung metastases

The passive application of Trastuzumab and Pertuzumab has demonstrated remarkable success in the clinical outcome patients with Her-2/neu positive metastatic breast cancer. However, active immunization mimotope/B cell epitope-based vaccines can induce production corresponding mAbs by patient’s immune system. We have developed a B peptide-based vaccine (HerVaxx) comprising Trastuzumab’s binding site. In settings, been shown to reduce primary tumor growth inducing polyclonal anti-tumor responses immunological memory. was also result loss expression, phenomenon similarly observed clinic after treatment Trastuzumab. Applying lung metastasis mouse model, here we tested multi-peptide containing HerVaxx mimotope for prevention metastases formation investigated expression. Mice were vaccinated vaccine, tail-vein injected mammary carcinoma cells expressing human Her-2/neu, histological evaluations mice lungs carried out. A significantly reduced either Pertuzumab, HerVaxx, or combination both, associated decreased weights increased CD4+ CD8+ T infiltration. Markedly, along overall reduction Her-2 metastases, Her-2/neu-negative tumors but PD-L1 expression observed. Our data might serving as secondary intervention adjuvant settings prevent recurrence spread. Furthermore, suggests therapy involving an anti-PD-L1 checkpoint inhibitor from PD-L1. Such alternately target be adapted stage progression phase disease remission metastases.