Shares of Biohaven Pharmaceutical (BHVN) are sliding despite the company having announced that two Phase 3 clinical trials for its migraine drug, rimegepant, met their efficacy endpoints. While William Blair analyst Tim Lugo understands the focus on comparing the results with the recent ubrogepant Phase 3 data from competitor Allergan (AGN), he argued that comparisons may be complicated as Biohaven did not allow rescue medications or re-dosing. PHASE 3 CLINICAL TRIALS: Biohaven Pharmaceutical has announced what it called “positive” top-line results from both of its two Phase 3 clinical trials of rimegepant, an oral CGRP receptor antagonist for the acute treatment of migraine. In each trial, rimegepant met the co-primary efficacy endpoints of superiority to placebo, at two hours post-dose, on pain freedom and freedom from the most bothersome symptom. In addition to efficacy observed on the co-primary registrational endpoints, onset of pain relief was observed early after rimegepant treatment with numerical separation evident between 30-45 minutes post-dosing, Biohaven noted. It also said rimegepant was found to be both safe and well-tolerated in the two Phase 3 studies with a safety profile similar to placebo. Biohaven says it is on schedule to submit a New Drug Application for rimegepant in 2019. EFFICACY PROFILE ‘APPROVABLE’: Following Biohaven’s news, Piper Jaffray analyst Charles Duncan said that while the placebo-adjusted difference at 2 hours seen in the Phase 3 studies of Biohaven’s rimegepant in acute migraine may be a point of debate among investors, he sees the data as compelling from a single dose in the “real world” setting. Duncan also said he thinks the 2-8 hour response rates support a differentiated profile and noted that rimegepant looks relatively safe and well-tolerated. Further, the analyst told investors that he views the acute efficacy and safety results as an important regulatory hurdle cleared and potentially a driver of prescriber preference in the commercial setting, both within and outside of the CGRP class. Duncan, who contends that rimegepant’s efficacy profile appears “approvable and clinically meaningful,” sees rimegepant as an over $1B drug. He reiterated an Overweight rating on Biohaven shares. COMPARISONS TO COMPETITORS: Meanwhile, William Blair’s Lugo told investors in a research note of his own that he believes Biohaven’s Phase 3 data confirmed rimegepant’s efficacy and “clean” safety profile. Lugo acknowledged that he understands the focus on comparing the results with the recent ubrogepant Phase 3 data from Allergan, but noted that comparisons are complicated as Biohaven did not allow rescue medications or re-dosing. Given the likely primary care market where these new therapies will be marketed, the analyst views rimegepant’s clean safety profile as “impressive” and likely a strong differentiator versus Allergan’s drug. He reiterated an Outperform rating on Biohaven shares. Needham analyst Alan Carr also commented on the results, saying that while rimegepant in acute migraine treatment showed a placebo-adjusted impact on pain that was “less impressive” than that of Eli Lilly’s (LLY) lasmiditan and Allergan’s ubrogepant in their respective phase 3 trials, rimegepant safety data was impressive and the drug appears better tolerated than lasmiditan. The possible rimegepant safety advantage may be a deciding factor for commercial success, the analyst contended. Carr reiterated a Buy rating on Biohaven shares. PRICE ACTION: In early afternoon trading, shares of Biohaven have dropped about 21% to $19.69, while Allergan’s stock has slipped almost 2% to $156.82.