ANPEP and cancer: Even if APN is effective at a relatively large concentration (e.g., in the low millimolar range) and proTAME is a prodrug that requires activation by esterases before it reaches the target cells [16], the combined use of our novel APN analogues such as Cbz-APN with proTAME and/or derivatives of this prodrug represents an interesting therapeutic opportunity to treat diverse types of aggressive cancers.