DUBLIN – Abivax SA has seen enough of an efficacy signal in a phase IIa trial of its first-in-class HIV drug ABX464 to warrant another phase IIa, to test its potential to delay viral rebound after cessation of therapy. "It's a proof of concept – it's a small phase IIa again," Abivax's chief medical officer, Jean-Marc Steens, told BioWorld Today.