It really depends if you are dealing with a large company or an individual landlord. I know for my tenants, if they have something like this I have no problem working with them. You will most likely lose your deposit though. If you are able to find another tenant for the property then the landlord may also be more receptive.
Read your lease top to bottom and check for anything that spells out the terms of an early termination. Be prepared to pay a penalty since the landlord has to remarket the property before they planned to.
Do not risk placing someone else in the property behind your landlord's back. Something like that is grounds for a lease termination by the landlord meaning it will show up as an eviction if you get found out. Honesty is the best policy in this case. You signed a contract and there are legal remedies to get out of it but it will probably cost you some money.