KAX kax 9-[(1~{R},6~{R},8~{R},10~{S},15~{R},17~{R},18~{S})-8-(6-aminopurin-9-yl)-18-fluoranyl-3,12-bis(oxidanyl)-3,12-bis(oxidanylidene)-2,4,7,11,13-pentaoxa-3$l^{5},12$l^{5}-diphosphatricyclo[13.3.0.0^{6,10}]octadecan-17-yl]purin-6-amine KAX