Shares of Cara Therapeutics (NASDAQ: CARA), a clinical-stage biopharmaceutical company focused on treating pain and pruritus (itching), surged an impressive 15% in March, according to data from S&P Global Market Intelligence. Two factors appear to have played a key role in pushing shares of Cara noticeably higher.Without question, the biggest catalyst last month was the release of positive top-line data from Part A of its phase 2/3 trial for IV CR845 in patients with chronic kidney disease-associated pruritus (known officially as uremic pruritus).