Lewis is co-inventor of the proprietary Dynamic Polyconjugate (DPC) technology – which includes the drug delivery vehicle Ex1.
Arrowhead stocks dropped over 60% and in response, the California-based company announced a 30% staff cut.
Arrowhead claims it will continue clinical development of the ARC-500, ARC-520 and ARC-AAT therapies, but using an alternative DPC – completely abandoning use of Ex1.
In a statement, the firm explained - “During ongoing discussions with regulatory agencies and outside experts, it became apparent that there would be substantial delays in all clinical programs that utilise EX1”.
David Lewis was appointed CSO in 2013, following two years of overseeing the clinical development of ARC-520 at the R&D facility in Wisconsin, US.
Lewis will formerly exit the company in two weeks.