Multiple myeloma (MM) is a deadly plasma cell cancer residing in the bone marrow, where the cells receive all the necessary growth signals. IGF-1 is one of the key growth signals. It is important that new therapies are non-toxic for the patient but highly selective for the tumor target. PPP (picropodophyllin) is a new inhibitor of the IGF-1 receptor fulfilling the above criteria. Our studies so far have shown that PPP selectively inhibits MM cell growth. The present study aims at confirming these data with studies in a therapeutic setting in in vivo mouse models.