When will a court grant leave to amend a motion dismissed for failure to state a claim?

Federal Rule of Civil Procedure 15 provides that courts should freely grant leave to amend when justice requires it. Accordingly, when a court dismisses a complaint for failure to state a claim, "leave to amend should be granted unless the court determines that the allegation of other facts consistent with the challenged pleading could not possibly cure the deficiency." DeSoto v. Yellow Freight Sys., Inc., 957 F.2d 655, 658 (9th Cir. 1992) (internal quotation marks omitted). Amendment may be denied, however, if amendment would be futile. See id.