EGFR-targeted humanized single chain antibody fragment functionalized silica nanoparticles for precision therapy of cancer.

The combination of highly specific targeting ability and potent killing effect has made antibody-drug conjugates (ADCs) a popular area of focus in the development of anti-cancer drugs. However, the large molecular weight of IgG antibodies (∼ 150 kDa) often faces challenges in penetrating capillaries and stroma in tumor tissue. Moreover, when the drug-antibody ratio (DAR) is too low (DAR < 2) or too high (DAR > 6) it decreases the effectiveness of the ADC and further increases the potential for aggregation, overall clearance of the early system payload, and release rate. In this study, an EGFR-based single-chain antibody fragment (husA)-human serum albumin (HSA)-coupled FITC-labeled mesoporous silica nanoparticle (FMSN-DOX-H-husA) was developed. Chinese hamster ovarian cells express the husA, which is a single chain antibody fragment of the EGFR that has been humanized. The small molecular weight of the single chain antibody allows for shorter penetration into solid tumors and the absence of adverse effects of the Fc fragment. The modification of HSA improves the safety of the antibody nanoparticle couples by both improving the biocompatibility of the nanoparticles, prolonging the circulation time of the nanoparticles, and avoiding early release of the payload. Also, the humanization substantially reduces the immunogenicity. More importantly, the ratio of drug antibodies on nanoparticles was experimentally and computationally derived to be 11.8, providing a more accurate guide for clinical trials. The results of both in vivo and in vitro experiments indicated promising antitumor activity and safety of FMSN-DOX-H-husA. Thus, this antibody-drug conjugate provided a hopeful option for cancer treatment.