It is hypothesized that the introduction of HER-Vaxx after 1L treatment in patients that have progressed under trastuzumab may overcome potential resistance against trastuzumab in combination with chemotherapy and can be continued after chemotherapy is terminated. Based on pre-clinical data HER-Vaxx may also synergize with pembrolizumab and therefore serve as a potentially better tolerated and chemotherapy-free treatment opportunity in metastatic patients that progressed under their previous therapy.~The study is designed to generate safety data and efficacy signals to support further development of HER-Vaxx in ≥2L mGC/GEJ cancer after progression with trastuzumab.~The study includes two treatment arms that will be analyzed independently using a 2-Stage design:~Arm 1: HER-Vaxx in combination with chemotherapy (ramucirumab plus paclitaxel)~Arm 2: HER-Vaxx in combination with pembrolizumab.~All patients must have received trastuzumab and progressed after 1L to be eligible for enrolment. Patients who have received an immune checkpoint inhibitor (ICI) previously will exclusively be enrolled in Arm 1 (HER-Vaxx + chemotherapy). Patients who are naïve to ICI treatment will exclusively be enrolled into Arm 2 (HER-Vaxx + pembrolizumab).
This is a Phase 2, signal generating, open-label, 2-Arm, non-randomized study, in patients with metastatic HER2/neu over-expressing gastric cancer or gastroesophageal adenocarcinomas.