Albumin is accumulated in tumor tissues, either due to the leaky capillary system and defective lymphatic drainage of tumors [1] or through an active gp60/caveolae-mediated transport process across tumor blood vessel endothelium [2, 3]. Importantly, albumin is taken up by proliferating tumor cells via endocytosis and macropinocytosis, then catabolized by lysosomal degradation to support de novo protein synthesis, energy, and tumor growth [4]. The accumulation of albumin in solid tumors provides potential rationale for albumin-based drug delivery systems to preferentially target tumors. The nab technology enables sirolimus to associate with albumin through non-covalent hydrophobic interactions to create a suspension of nanoparticles with an average size of < 100 nm