Multiple Treatment Session Study to Assess GSK2398852 Administered Following and Along With GSK2315698

The study is intended to evaluate whether monthly repeated courses of administration of GSK2315698 followed by GSK2398852 is associated with a reduction in cardiac amyloid load in patients with cardiac amyloidosis, monitored by cardiac magnetic resonance imaging (CMR) and echocardiography (ECHO), and whether this is associated with an improvement in cardiac function. Cohort 1 is transthyretin cardiomyopathy (ATTR-CM) , cohort 2 is patients with immunoglobulin light chain (AL) systemic amyloidosis at greater than 6 months post chemotherapy, cohort 3 newly diagnosed AL systemic amyloidosis undergoing chemotherapy. Primary objectives for the study are assessment of reduction in cardiac amyloid load after repeated administrations of Anti-SAP treatment as evaluated by CMR in all study groups and assessment of safety \& tolerability of repeated administration of Anti-SAP treatment, including compatibility with chemotherapy treatment in patients with AL systemic amyloidosis. This is an open label, non-randomised, three-group, monthly repeat Anti-SAP treatment study in systemic amyloidosis patients with cardiac dysfunction caused by cardiac amyloidosis. Subjects will receive up to 6 courses of Anti-SAP treatment. Maximum total duration for a subject in the study is approximately 18 months.