Investing in small-cap biotech stocks can be scary and exciting at the same time. A pipeline failure can devastate the stock, while great clinical results can cause share prices to skyrocket.There are more small-cap biotech stocks than any investor can realistically keep up with. But three stocks I think you'll want to keep on your radar are Abeona Therapeutics (NASDAQ: ABEO), Atara Biotherapeutics (NASDAQ: ATRA), and Viking Therapeutics (NASDAQ: VKTX).