The Pennsylvania Driver's Manual states that if you plan on using your learner's permit for driving outside the Commonwealth of Pennsylvania to check with your insurance company and the other states' Department of Transportation (or Department of Motor Vehicles) to make sure your learner's permit is valid.
So it would appear that PennDOT allows for you to drive out of state with a learner's permit but you would need to check with your insurance company to make sure it would cover you driving out of PA with the permit.
You also would need to verify with the other states DMVs you plan to drive through or to, such as West Virginia, Virginia, North Carolina and even Maryland depending upon where in PA you are starting from, to find out if a Pennsylvania learners permit will allow you to drive on their roadways.
In general most states do allow you to drive with an out of state learner' permit but to make certain that you are not breaking any of your PA permit contact their DMVs.
It may be that in some states there will be extra restrictions placed on your driving privileges, on top of your home state restrictions which even out of state you will need to follow.