The top management of Wall Street highflier Gilead Sciences is facing a challenge that confronts many companies that have flourished but face the criticism that they need to give back to the global community in more direct ways. The fundamental question boils down to this: Can a company do well by doing good, for the sake of the world, and still do well - for its demanding stockholders? It's a major issue, as Gilead Science's stock has climbed about 40% so far this year, on the wings of the highly successful drug Sovaldi, which combats hepatitis C. The drug carries an enormous price tag of $1,000 per pill under a 12-week regimen that typically costs $84,000.