The primary endpoint was to evaluate the clinical efficacy of hu3S193, a humanized monoclonal antibody against the Lewis-Y antigen, in advanced hormone positive breast cancer after failure of at least one line of endocrine therapy.
Phase II clinical trial, testing the efficacy of a humanized monoclonal antibody against the Lewis-Y antigen (Le y)
Laura Testa 1,2, Ruffo Freitas-Junior3, Sergio V Serrano4, Roberto J Arai 1, Marina C Zorzetto4,5,Oren Maletz5 ,Max S Mano1 and Paulo M Hoff 1,2.
1.Instituto do Câncer do Estado de São Paulo, SP, Brazil; 2.Hospital Sírio Libanês, SP, Brazil; 3.Universidade Federal de Goiás, GO, Brazil; 4.Hospital de Câncer de Barretos, SP, Brazil and 5.Recepta Biopharma.
Background. The Lewis-Y (Le y) antigen is a blood group-related antigen expressed in over 70% of epithelial cancers. It is expressed in 44% of breast cancers.
Objectives. The primary endpoint was to evaluate the clinical efficacy of hu3S193, a humanized monoclonal antibody against the Lewis-Y antigen, in advanced hormone positive breast cancer after failure of at least one line of endocrine therapy.
Methods. This multicenter, single arm, phase II trial enrolled eligible patients to receive hu3S193 weekly at a dose of 20 mg/m2, intravenously. Efficacy was measured as clinical benefit rate (objective response or stable disease for at least 24 weeks).
Results. Of 49 patients screened, 27 (55%) were Le y positive. Of these 27, only 20 were eligible for efficacy analysis. No complete or partial responses were observed. Four patients had stable disease for 24+ weeks (clinical benefit rate 20%). One patient remains on study drug maintaining stable disease for over 2 years. This patient had high expression of Le y. The most common treatment-related adverse events were headache (50%), cough (45,5%) and nausea/vomiting (31,8%).
Hu3S193 lacked sufficient activity in is trial and the investigators stopped accrual at the first interim analysis. High expression of Le y might play a role in selecting patients to this strategy.