Vanda's ($VNDA) in-development eczema treatment failed to make a meaningful difference in a mid-stage trial, but the company isn't giving up, pointing to positive signs among a subset of patients. The drug, tradipitant, failed to meet its primary goal of reducing eczema-related itching due to "a very high placebo effect," Vanda said. But, looking at patients with higher blood levels of the drug, the company noted a significant correlation between tradipitant concentration and effect on eczema, a sign CEO Mihael Polymeropoulos deemed "encouraging." Investors were less optimistic, sending Vanda's shares down nearly 7%.More