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

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.

Zoledronic acid slows down rat primary chondrosarcoma development, recurrent tumor progression after intralesional curretage and increases overall survival.

Chondrosarcoma is a difficult musculoskeletal tumor to treat. Surgical treatment leads to severe disability, with high rates of local recurrence and life threat. No adjuvant therapy is effective in differentiated chondrosarcomas. Bisphosphonates (BPs) are a class of molecules which is effective in malignant bone diseases. The aim of the present study was to determine the effects of zoledronic acid (ZOL) on chondrosarcoma tumor progression. ZOL was tested in vivo (s.c. 100 microg/kg, twice a week) in a rat chondrosarcoma model and in vitro (10(-7)-10(-4) M) on cells derived from this model. Two types of animal models were assessed, the first simulated development after intralesional curettage, the second nonoperative development of the tumor. Cell proliferation, caspase-1, -3 activities and cell cycle analysis were studied. The results revealed that ZOL slows down primary tumor development, tumor progression after intralesional curretage and increases overall survival. ZOL inhibits cell proliferation and increases cell death, with no significant variation of caspase-1 and -3 activities and cell cycle profiles. The present study demonstrates for the first time that in addition to surgery, the therapy of chondrosarcoma with BPs might be beneficial. Because of these first results, new therapeutic approaches of chondrosarcoma must be considered, mainly for low grade chondrosarcoma when disabling operation is planned and when only intralesional resection can be undertaken.