"Maybe", but no guarantees. Ordinarily you have to deal with just your landlord; here you also have to deal with your roommates.

1. On the landlord side even if your landlord accepts a substitute doesn't mean you're off the lease unless the landlord says so (in writing). The landlord may simply have 4 people to bank on instead of 3.

2. On the roommate side you have a double-edged sword unless they know someone who would want to take your place: if you tell them why you want out, or if you rat on them for having additional people staying there which may be a lease violation, they may just be uncooperative, and if you don't tell them then showing the place may be your biggest problem if it's a mess. You formed something of a "partnership" with them and they may not be happy about a stranger taking your place. Of course if they're happier without you and just the two of them, or if one of their guests might like to become permanent, then you're back to only dealing with the landlord. I have to believe they must be counting on you for 1/3 of the rent though.

3. While it may not be a "legal" answer, the counselor part of being a lawyer suggests there may be some other ways of making do until the lease is up, which would be to sit down with your roommates and tell them the 3 of you could be evicted if the landlord finds out too many people are staying there, and that you could all lose your security deposit if the place becomes such a mess -- in other words while you all may have thought it was a great idea to move in together, or you needed each other because none of you alone could have afforded the place, some rules do make for a better situation. You might even find one of them or both could be allies if there are things bothering them too. In that kind of give-and-take, you need to remain flexible too so a "no guests ever" policy is the kind of thing that won't help. And if the place is that much of a mess and you're all working, maybe you three should consider having someone paid (it could even be one of you as a rent discount) to keep the place looking right. Good luck!!!