Fig 4. Adding anti-estrogen therapy further improves the efficacy of lumretuzumab and pertuzumab.

HBCx-19 ER+/HER2-low/HER3+ breast cancer xenograft-bearing mice (n = 10 per treatment group) were treated with lumretuzumab (3 mg/kg i.p.), pertuzumab (3 mg/kg i.p.), and fulvestrant (50 mg/kg i.m.) either as single agents or in combination. Lower (sub-optimal) doses of lumretuzumab and pertuzumab were used to discriminate the additional contribution of fulvestrant. All treatments were given weekly beginning on Day 26 when median tumor size was 100–150 mm³ for 6 weeks (until Day 57).