The worrying thing to me is that they apparently decided this retirement last week (finalized on June 13). And so, did they have an early look at the AB-506 capsid inhibitor data and was not good? I hope not but time will tell very shortly:
"AB-506 showed attractive potency and PK in preclinical studies and has advanced into clinical development in a Phase 1a/1b study, initially in healthy volunteers followed by HBV patients. Top-line data from this ongoing study are anticipated in July 2019. Arbutus subsequently plans to evaluate a combination regimen, combining AB-506 with RNAi agent AB-729 and approved nucleoside analogs, with the goal of increasing cure rates in HBV patients."