About those positive Phase 3 results 

Biocryst Pharmaceuticals and Array Biopharma each announced positive outcomes from Phase 3 clinical trials yesterday. Investors, however, reacted to the good news in starkly different ways.

A first-of-its-kind oral therapy for a rare, genetic disease called hereditary angioedema successfully reduced the rate of swelling “attacks” experienced by patients compared to placebo, achieving the main goal of Biocryst’s Phase 3 clinical trial. But the magnitude of the benefit demonstrated by the Biocryst once-daily pill, called BCX7353, was relatively small, raising investor concerns that the new therapy, while convenient for patients, will find it difficult to compete against more effective injectable medicines already on the market. Biocryst’s stock price was cut in half.

Array fared better. A triple-combination therapy that includes two Array drugs called Braftovi and Mektovi made tumors disappear and prolonged the survival of patients with advanced colon cancer caused by a specific genetic mutation. The positive results, culled from an early look at a large clinical trial, are expected to lead to approvals in the U.S. and Europe and blockbuster commercial sales. Investors pushed Array’s stock price higher by 23%.