Long-term follow-up of patients concomitantly treated with hormone therapy in a prospective controlled randomized multicenter clinical study comparing STn-KLH vaccine with KLH control in stage IV breast cancer following first-line chemotherapy

Abstract

2603 Background: Theratope (T) is an investigational therapeutic cancer vaccine consisting of a synthetic form of the tumor-associated antigen Sialyl Tn (STn) conjugated to the carrier protein keyhole limpet hemocyanin (KLH). This abstract reports a survival follow-up of the phase III trial with emphasis on the subgroup concomitantly treated with hormone therapy. Methods: Metastatic breast cancer patients (MBC pts) who had no evidence of disease or non-progressive disease following any first-line chemotherapy were randomized 1:1 to receive adjuvant plus T or control (C) (adjuvant plus KLH). All pts received a single IV infusion of cyclophosphamide before vaccine. Primary endpoints were time to disease progression (TTP) and overall survival (OS). Pts were stratified by disease status and concomitant hormone therapy (HT). Results: 1028 pts were randomized: 34% received concurrent HT (n = 350). The concomitant treatment in the two treatment arms on hormone therapy (n = 180 T, n = 170 C) consisted mainly of S...