H.C. Wainwright Downgrades Aviragen Therapeutics (AVIR) to Neutral

H.C. Wainwright downgraded Aviragen Therapeutics (NASDAQ: AVIR) from Buy to Neutral.

Analyst Ed Arce commented, "Failure of vapendavir or ACQ-6 endpoint? We may never know. After market close, on February 13, Aviragen announced that the Phase 2b SPIRITUS trial of its lead drug candidate, vapendavir, missed its primary and several secondary endpoints. Recall, this trial was conducted across 68 sites in North America and Europe and was designed to assess the safety and efficacy of two doses of vapendavir (264 mg or 528 mg) for the treatment of human rhinovirus (HRV) infections in 455 subjects with moderate-to-severe asthma. In SPIRITUS, vapendavir failed to achieve statistical significance in the primary endpoint, least square (LS) mean change from baseline (day 1) to day 14 in Asthma Control Questionaire-6 (ACQ-6) score in the intent-to-infected (ITT-I) population (168 subjects with laboratory-confirmed HRV-infected patients). In particular, subjects that received 264 mg (n=54) or 528 mg (n=57) vapendavir exhibited an improvement in day 14 ACQ-6 scores of 0.75 and 0.79, respectively, compared to an improvement of 0.97 in the placebo group (n=57). In a very confusing result for us, the outsized placebo effect was so large that not only did it do better than either active drug arm, but it also represents 2.2x the magnitude of the placebo effect observed in the prior RHINO study (0.44), as measured by the similar ACQ-5 scoring tool. Furthermore, we expected the placebo response in SPIRITUS to be less than observed in RHINO, not more, given the substantially more severe (so called enriched) patient population of SPIRITUS. Aviragen was hoping to see at least a 0.5 placebo-adjusted improvement in ACQ-6, which is considered clinically meaningful. In addition, vapendavir also missed several secondary endpoints which include the lung function measure FEV1 and reduction in asthma exacerbations. However, SPIRITUS demonstrated statistically significant antiviral effects for patients that received vapendavir within 24 hours of first symptoms, consistent with previous Phase 2 studies. Turning to the safety profile, vapendavir was shown to be generally well tolerated. In our view, the negative SPIRITUS results exhibited several discordant features, most prominently: 1) the unusual improvement in ACQ-6 score in the placebo arm is completely inconsistent with the previous Phase 2 RHINO study; and 2) it is unclear why the reduction in viral load achieved by vapendavir did not translate into improvement of clinical symptoms. In order to tease out exact reasons for trial failure, Aviragen expects to disclose additional analyses of the trial data after comprehensive discussions with key experts in the field in the coming weeks. However, in any event, Aviragen has decided that it will no longer pursue any further development of vapendavir to treat asthmatics."

For an analyst ratings summary and ratings history on Aviragen Therapeutics click here. For more ratings news on Aviragen Therapeutics click here.

Shares of Aviragen Therapeutics closed at $0.68 yesterday.

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