Exhibit (a)(1)

EXHIBIT A

[from Letter from Thomas Watkins to Andrew Witty, dated April 19, 2012]

Albiglutide

• All efficacy and safety data available to GSK from the eight Harmony Phase 3 studies investigating the use of albiglutide in type 2 diabetes in the form of summary reports and/or tables and listings of data

• 2 year interim data from the 3 year Harmony studies

• Internal product sales forecasts through patent expiry

• Target product profile used in sales forecasts

• Supporting primary and secondary market research on potential product positioning, market share, pricing, and competition

Darapladib

• All efficacy and safety data currently available to GSK including the overall primary endpoint event rate for the SOLID-TIMI 52 and STABILITY studies to date

• Enrollment data for the SOLID-TIMI 52 and STABILITY studies

• Primary endpoint accumulation data

• Study protocols and statistical analysis plans for SOLID-TIMI 52 and STABILITY

• Written recommendations received from all independent data monitoring committee meetings

• Minutes from end of phase 2 or later regulatory meetings

• Internal product sales forecasts through patent expiry

• Target product profile used in sales forecasts

• Supporting primary and secondary market research on potential product positioning, market share, pricing, and competition