Trump doesn't give two sh*ts about the price of drugs, whether high or low.
He's lowering the prices to give a leg up to a republican running for senator in NJ. His name is Bob Hugin. He's the CEO of Celgene Corporation, a biopharmaceutical company.
https://en.wikipedia.org/wiki/Bob_Hugin
http://www.celgene.com/
Hugin is running against Bob Menendez and hasn't gained any ground b/c all he has is "Menendez disgraced the Senate and NJ and should resign."
Trump personally selected Hugin to run for the Senate notwithstanding his void of experience in government at any level. All he knows is business. (Sound familiar?)
So anyway, Trump will lower the price of drugs, give the credit for the idea to Hugin, who's running in a very very blue state.