Lake Forest-based biotech firm NeoPharm Inc. and pharmaceutical giant Pfizer Inc. will be left to iron out an agreement to develop cancer drugs after a ruling from an independent panel of arbitrators dismissed claims each company had made against the other. The two companies have been at odds over a 1999 licensing agreement and Pfizer’s role in developing two Neopharm cancer compounds. The dispute began two years ago between NeoPharm and Pharmacia Corp., which was purchased last year by Pfizer.