ALTTO (Adjuvant Lapatinib And/Or Trastuzumab Treatment Optimisation) Study; BIG 2-06/N063D

Treatment allocation was stratified by blocked randomization, with three stratification factors:

• Hormone receptor status: Estrogen Receptor (ER) and/or Progesterone Receptor (PgR) positive versus both negative.
• Axillary lymph node involvement: not assessed because of neoadjuvant chemotherapy versus node negative versus 1-3 positive nodes versus 4 or more positive nodes.
• Timing of adjuvant chemotherapy: concurrently with taxanes and targeted therapy (Design 2) and concurrently with non-anthracycline-based platinum chemotherapy and targeted therapy (Design 2B) versus all other chemotherapy completed before randomization (Design 1). Treatments delivered differed according to the timing and type of adjuvant chemotherapy.

The primary objective of this study was to compare disease-free survival (DFS) in subjects with HER2 overexpressing and/or amplified breast cancer randomized to trastuzumab for one year versus lapatinib for one year versus trastuzumab (12 or 18 weeks, according to assigned design) followed by a six week treatment-free interval followed by lapatinib (28 or 34 weeks, according to assigned design) versus trastuzumab in combination with lapatinib for one year (52 weeks).

Secondary objectives included treatment comparisons with respect to overall survival, time to recurrence, time to distant recurrence, safety and tolerability, and incidence of brain metastasis.

Based on the recommendation of the Independent Data Monitoring Committee (IDMC) at the first interim analysis (18-Aug-2011), the Lapatinib alone arm was discontinued prior to primary analysis due to futility. The IDMC also stated that the other three arms (trastuzumab alone, sequential trastuzumab/lapatinib arm and the combination arm) could continued as planned with no changes.

Key Inclusion Criteria:

• Patients >= 18 years of age with histologically confirmed, non-metastatic, operable and over expression/amplification of HER2 (3+ by IHC and/or FISH positive) primary breast cancer, treated with definitive surgery, with baseline LVEF >= 50%, known hormone receptor status (ER/PgR or ER alone) and ECOG performance status =< 1, were included.
• For Designs 1 and 2: Patients must have had received at least four cycles of an approved anthracycline-based (neo-) adjuvant chemotherapy regimen or a protocol specified exception.
• Approved, signed written informed consent obtained prior to any study specific screening procedures.

Key Exclusion Criteria:

• History of any prior (ipsi- and/or contralateral) invasive breast carcinoma, past (less than 10 years) or current history of malignant neoplasms, any clinically staged T4 tumor, or bilateral tumors.
• Concurrent anti-cancer treatment, except hormonal therapy or radiotherapy for the present breast cancer;
• Patients with positive or suspicious internal mammary nodes identified by sentinel node technique, which had not been irradiated or would not be irradiated, or patients with supraclavicular lymph node involvement.
• Any prior anti-HER therapy, which includes agents that target other members of the HER family of receptors, e.g. gefitinib (Iressa)
• (Neo-) or adjuvant chemotherapy using peripheral stem cell or bone marrow stem cell support;
• Serious cardiac illness or medical conditions.
• Any of the following abnormal laboratory tests immediately prior to randomization:

• Serum total bilirubin >1.5 x upper limit of normal (ULN). In the case of known Gilbert's syndrome, a higher serum total bilirubin (<2 x ULN) was allowed;
• Alanine amino transferase (ALT) or aspartate amino transferase (AST) >2.5 x ULN;
• Alkaline phosphatase (ALP) >2.5 x ULN;
• Serum creatinine >2.0 x ULN;
• Total white blood cell count (WBC) <2.5 x 10^9/L;
• Absolute neutrophil count <1.5 x 10^9/L;
• Platelets <100 x 10^9/L.
• Women of childbearing potential and male patients with partners of childbearing potential, who are unable or unwilling to use adequate contraceptive measures during study treatment, and pregnant or lactating women.
• Concomitant use of CYP3A4 inhibitors or inducers.