Aadi Bioscience’s first product, nab-sirolimus (sirolimus albumin-bound nanoparticles for injectable suspension, ABI-009), a highly active form of sirolimus (rapamycin) complexed with albumin, is based on the same technology as ABRAXANE® (nab-paclitaxel, Abraxis Bioscience, acquired by Celgene Corp in 2010 for ~$3B, 2019 sales >$1B)
Albumin is highly accumulated in tumor tissues, either due to the leaky capillary system and defective lymphatic drainage of tumors  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 . 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 a size of about 100 nm.
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