GSK presents data from its phase I Behold-1 trial for Mo-Rez

GSK (GSK) announced positive findings from its global phase I Behold-1 clinical trial for mocertatug rezetecan, Mo-Rez, a novel antibody-drug conjugate, ADC, targeting the B7-H4 antigen. At the highest doses evaluated, Mo-Rez monotherapy achieved confirmed objective response rates, cORR, of 62% in platinum-resistant ovarian cancer, PROC, and 67% in recurrent or advanced endometrial cancer, EC. These data will be presented for the first time in a late-breaking oral session at the Society of Gynecologic Oncology, SGO, Annual Meeting on Women’s Cancer in San Juan, Puerto Rico. At the highest doses evaluated in BEHOLD-1, few patients needed to stop treatment because of a treatment-related adverse events. The most common TRAE was nausea. Grade greater than or equal to3 TRAEs occurred in 64% and 54% patients in PROC and EC, respectively, and were predominantly haematologic, as expected for treatments in this class. Overall rates of interstitial lung disease or pneumonitis were low and all cases were mild to moderate. The interim analysis showed the median duration of response had not yet been reached. Based on the findings from this study, the recommended dose for the first of the phase III trials, BEHOLD-Ovarian01 and BEHOLD-Endometrial01, is 5.8 mg/kg.