Standard-of-care, first-line therapy for patients with advanced HER2+ gastric/gastroesophageal junction adenocarcinoma is chemotherapy plus trastuzumab, a monoclonal antibody (mAb) targeting HER2. Margetuximab is an Fc-optimized mAb that binds HER2. Retifanlimab, a humanized IgG4 mAb, binds to PD-1 and blocks its interaction with PD-L1/2. Tebotelimab, an IgG4κ bispecific DART® molecule, binds PD-1 and lymphocyte activation gene 3 concomitantly, disrupting these nonredundant inhibitory pathways to further restore exhausted T-cell function. Here, we describe the design and rationale of the randomized, open-label, Phase II/III MAHOGANY trial evaluating margetuximab plus retifanlimab with/without chemotherapy and margetuximab plus tebotelimab with chemotherapy in first-line unresectable metastatic/locally advanced gastroesophageal junction adenocarcinoma. Primary end points include objective response rate, overall survival and safety/tolerability. Clinical trial registration: NCT04082364 (ClinicalTrials.gov).
Keywords: HER2; I-O combination; LAG-3; PD-1; checkpoint inhibitor; first-line therapy; gastric cancer; gastroesophageal adenocarcinoma; gastroesophageal junction cancer; immuno-oncology.