SN38-SPL9111

Harnessing the modulation of redox homeostasis represents a promising anticancer strategy. Here, we design and evaluate Se-SN38, a prodrug of the camptothecin (CPT) derivative 7-ethyl-10-hydroxycamptothecin (SN38) with a cyclic five-membered diselenide moiety for redox-triggered activation. We demonstrate that Se-SN38 exhibits superior cytotoxicity in various cancer cell lines over the parent drug SN38 or the control prodrug S-SN38, a sulfur analogue of Se-SN38. This increased potency is attributed to the efficient release of SN38 and induction of oxidative stress, as demonstrated by a significant rise in reactive oxygen species production, along with a marked depletion of cellular total thiols and a decreased GSH/GSSG ratio. Furthermore, Se-SN38 treatment leads to inhibition of thioredoxin reductase activity, disruption of mitochondrial membrane potential, and induction of DNA damage, culminating in apoptosis. These findings suggest that Se-SN38 represents a promising strategy to enhance the therapeutic efficacy of CPT derivatives by exploiting the unique redox-active properties of cyclic five-membered diselenide to induce oxidative stress and apoptosis.

For most cancers, the combination of chemotherapy drugs is a promising approach. The combination of DNA damage agent Exatecan and proteolysis targeting chimera (PROTAC) agent ARV-825, which is a selective bromodomain-containing protein 4 degrader, can further improve efficacy through the DNA damage-repair mechanism. The Cathepsin B-sensitive prodrug with high albumin affinity of Exatecan (C14-VC-PAB-Exa) was introduced and co-encapsulated with ARV-825 into the nano-drug delivery system for improving the physicochemical properties of the two drugs. To promote the translation of Exatecan and the PROTAC into the clinics, it is important to develop a reliable and high-throughput bioanalytical method for the simultaneous determination of Exatecan, C14-VC-PAB-Exa, and ARV-825 that can evaluate the pharmacokinetic behaviors of the analytes. In this study, an HPLC-MS/MS method after preparation by one-step protein precipitation was developed and fully validated. The analytes were eluted completely on a ZORBAX SB-C18 column by gradient elution. Multiple reaction monitoring mode with positive electrospray ionization was applied to quantify the analytes. The validated method on selectivity, linearity (r ≥ 0.995), precision and accuracy (< 15 %), extraction recovery (> 88.0 %), matrix effect (< 9.1 %), carry-over, and stability were within the predefined acceptance criteria. The method was successfully applied to the pharmacokinetic study of Exatecan, C14-VC-PAB-Exa, and ARV-825 in rats for the first time. The proposed robust and economical method will be an alternative bioanalytical procedure for Exatecan and ARV-825 in the future. What is more, the present work could provide a reference for the clinical combination of the two drugs.