Current study is two group study. In Group A, Patients with fewer than two active lesions will be enrolled and exposed to photoprovocation (PV) for 3 consecutive days. Patients that develop PV lesions at any time during this period, as determined by the local investigative team, will receive 1% strength GSK2646264 on 1 lesion and placebo on 1 lesion daily and either 1% strength GSK2646264 or placebo on an area of uninvolved skin, for skin pharmacokinetic (PK) of study drug, for 28 days.