Preheat oven to 400 degrees F. On 15 1/2" by 10 1/2" jelly roll pan, or a large cookie sheet, spread bread cubes in one layer. Place in oven; toast 11-13 minutes or until golden, stirring cubes once halfway through baking. Cool on wire rack 10 minutes.
Meanwhile, in large bowl, with fork, mix olive oil, wine vinegar, chopped capers, 1/4 teaspoon salt, and 1/4 teaspoon freshly ground black pepper until blended. Add chopped tomatoes, white beans, flaked tuna, torn basil, and bread cubes to bowl; toss well to coat all ingredients with dressing.