The start in early April by Biohaven Pharmaceutical Holding Co. Ltd. of the phase II/III trial with BHV-3500 in acute treatment of migraine brought renewed attention to the calcitonin gene-related peptide (CGRP) receptor antagonist space, even as rumors swirled later in the month that the New Haven, Conn.-based firm was mulling a sale – if not of the company, then of its CGRP platform.