STRIDE - A Randomised, Double-Blind, Phase III Study of Stimuvax® in combination with Hormonal Treatment versus Hormonal Treatment alone for First-line Therapy of endocrine-sensitive Advanced Breast Cancer

INTERVENTION: Intervention1: Investigational Arm ‐ L‐BLP25: 1000µg* of L‐BLP25 intended for Subcutaneous administration and hormonal treatment (standard dose). 1. Investigational Arm ‐ All subjects randomized to the investigational arm will begin the following treatment regimen within four days of randomization: ? Cyclophosphamide: o A single I.V. infusion of 300 mg/m2 of cyclophosphamide administered three days prior to the first L‐BLP25 vaccination. The maximum allowable dose of cyclophosphamide is 600 mg. ? L‐BLP25 and hormonal treatment: o Primary treatment phase: Eight consecutive weekly subcutaneous vaccinations with 1000 μg* L‐BLP25 at Weeks 1, 2, 3, 4, 5, 6, 7, and 8 and hormonal treatment o Maintenance treatment phase: Vaccinations with 1000 μg* L‐BLP25 at six‐week intervals, beginning at Week 14 and hormonal treatment and continuing until PD is documented or the subject discontinues for any other reason. * calculated as mass of lipopeptide (antigen) Control Intervention1: Control Arm ‐ 0.9% sodium chloride & L‐BLP25 placebo: 2. Control Arm ‐ All subjects randomized to the control arm will begin the following treatment regimen within four days of randomization: ? 0.9% sodium chloride: ‐ A single I.V. infusion of 0.9% sodium chloride administered three days before initial dosing of placebo. ? L‐BLP25 placebo and hormonal treatment. ‐ Primary treatment phase: Eight consecutive weekly subcutaneous treatments with L‐BLP25 placebo at Weeks 1, 2, 3, 4, 5, 6, 7, and 8 and hormonal treatment ‐ Maintenance treatment phase: Treatment with L‐BLP25 placebo at six‐week intervals, beginning at Week 14 and hormonal treatment and continuing until PD is documented or the subject discontinues for any other reason. CONDITION: Breast Cancer PRIMARY OUTCOME: Progression‐free survival (PFS) time will be analyzed as the main measure of treatment outcome. PFS time is defined as the duration from randomization to first observation of PD by the independent radiological review or death.‐‐‐‐‐‐Timepoint: First assessment (of PFS) after 15 monthsl then on an ongoing basis SECONDARY OUTCOME: Measurement Response Evaluation Criteria in Solid Tumours (RECIST)‐‐‐‐‐‐Timepoint: Pre‐treatment visit, every 8 weeks thereafter, starting with week 14 during the Maintenance Treatment, and at the End of Study visit. INCLUSION CRITERIA: 1.Postmenopausal women 2. ER+ and/or PgR+, histologically or cytologically confirmed primary carcinoma of the breast 3. Expressing at least one of the following five HLA haplotypes, as centrally assessed by HLA genotyping from whole blood: HLA‐A2, ‐A3, ‐A11, ‐B7, or ‐B35 4. Locally advanced, recurrent, or metastatic breast cancer (Subject must have at least one lesion not located in bone). 5. Measurable disease by RECIST, and inoperable 6. ECOG performance status of 0 or 1 7. Adequate hematologic, hepatic, and renal function within two weeks prior to initiation of therapy, as defined by the protocol