Certified GKH Gardening Expert
That's what they do sometimes if not trained, pruned and staked early on. All you can do is to select one or more of the straightest stems to stake. Then if it is still spreading and leaning more that what you consider acceptable, you can prune the growth back to reduce branch end-weight and directional prune to straighten it up a little. (pruning cuts will drip white rubbery sap, so be prepared for that or don't prune, there is no way to stop it except with time)
Have it in pot big enough to sink the stakes to an appropriate depth and to provide substantial anchorage for the leaning weight or it will be prone to tip over.