Quaternary ammonium-melphalan conjugate for anticancer therapy of chondrosarcoma: in vitro and in vivo preclinical studies

Abstract

Cartilage tumours present ongoing therapeutic challenges due to their chondrogenic extracellular matrix that potentially hampers drug delivery, their low percentage of dividing cells, and their poor vascularity. In this context, and based on the affinity of the quaternary ammonium moiety for proteoglycans (PG), we developed a strategy that uses the quaternary ammonium function to selectively deliver DNA alkylating agents to the cartilage tumour tissue. We engineered the quaternary ammonium derivative of melphalan (Mel-AQ) and assessed its antitumoural activity in vitro and in vivo. In vitro, micromolar concentrations of Mel-AQ inhibited the proliferation of human HEMC-SS chondrosarcoma and Saos-2 osteosarcoma cell lines. Moreover, 24-h incubation with 20 μM Mel-AQ induced a 2.5-fold increase in S population and a 1.5-fold increase in subG0G1 population compared to controls. In vivo, Mel-AQ demonstrated antitumour activity in the orthotopic model of primary Swarm rat chondrosarcoma. When given to chondrosarcoma-bearing rats (three doses of 16 μmol/kg at days 8, 12 and 16 post-implant), Mel-AQ demonstrated an optimal antitumour effect at day 43, when tumour cell growth inhibition peaked at 69%. Interestingly, the treatment protocol was proved well tolerated, since the animals showed no weight loss over the course of the study. This antitumoural effect was assessed in vivo by scintigraphic imaging using (99m)Tc-NTP 15-5 developed in our lab as a PG-targeting radiotracer, and tumour tissue was analyzed at study-end by biochemical PG assay with Alcian blue staining. Mel-AQ treatment led to a significant decrease in the PG content of tumoural tissue. These experimental results highlighted the promising antitumour potential of Mel-AQ as a PG-targeting strategy for therapeutic management of chondrosarcoma.

Rapid and simple flow injection analysis tandem mass spectrometric method for the quantification of melphalan in a lipid‐based drug delivery system

“…In addition to poor solubility, melphalan shows minimal chemical stability in aqueous medium as it hydrolyzes into hydroxymelphalan . Therefore, attempts to improve the solubility and stability of melphalan were conducted by either chemical modifications or by engineering novel drug delivery systems, such as nano‐systems …”

New chondrosarcoma cell lines and mouse models to study the link between chondrogenesis and chemoresistance

“…42 Similarly, based on the affinity of the quaternary ammonium moiety for proteoglycans present in the cartilaginous matrix, a quaternary ammonium-melphalan conjugate was engineered and showed antitumor effects in CS-bearing rats. 43 In conclusion, the phenotype of CS cell lines in monolayer is significantly altered, whereas chondrogenic 3D pellets represent much more valuable models for this pathology, especially to study the link between chondrogenesis and chemoresistance. In comparison with animal models, these culture conditions are easier, more reproducible and ethical, although important factors such as angiogenesis or metastasis are still missing.…”

Proteoglycans as Target for an Innovative Therapeutic Approach in Chondrosarcoma: Preclinical Proof of Concept

“…Mel was used as its hydrochloride form after treatment of Mel (Interchim) with a solution of 2 N hydrochloric acid in diethyl ether. The QA conjugate of Mel (Mel-QA) was prepared as already published (13,17) and fully characterized (Supplementary Fig. S1).…”

“…This radiotracer is currently transferred into clinic for a first into human study. In parallel, we developed a therapeutic approach with a QA derivative of melphalan (Mel-QA), an alkylating agent, that showed promising results from in vitro and in vivo preclinical experiments (13). The aim of the current study was to characterize this therapeutic strategy.…”