RRM2 and cancer: CALAA-01 comprises different components such as cyclodextrin-based polymer (CDP), external PEG chains to improve the stability of nanoparticles in biological fluids, a human transferrin protein (TF) to target TF receptors (TFR) on cancer cells surface, and a siRNA specific for M2 subunit target of the ribonucleotide reductase protein (RRM2).