Regional chemotherapy in an experimental model of Wilms' tumor in rats

GEP-NETS update: Interventional radiology: role in the treatment of liver metastases from GEP-NETs

Neuroendocrine tumors from gastro-pancreatic origin (GEP-NET) can be responsible for liver metastases. Such metastases can be the dominant part of the disease as well due to the tumor burden itself or the symptoms related to such liver metastases. Intra-arterial therapies are commonly used in liver only or liver-dominant disease and encompass trans-arterial chemoembolization (TACE), trans-arterial embolization (TAE), and radioembolization (RE). TACE performed with drug emulsified in Lipiodol has been used for the past 20 years with reported overall survival in the range of 3-4 years, with objective response up to 75%. Response to TACE is higher when treatment is used as a first-line therapy and degree of liver involvement is lower. Benefit of TACE over TAE is unproven in randomized study, but reported in retrospective studies namely in pancreatic NETs. RE provides early interesting results that need to be further evaluated in terms of benefit and toxicity. Radiofrequency ablation allows control of small size and numbered liver metastases, with low invasiveness. Ideal metastases to target are one metastasis <5 cm, or three metastases <3 cm, or a sum of diameter of all metastases below 8 cm. Ablation therapies can be applied in the lung or in the bones when needed, and more invasive surgery should be probably saved for large-size metastases. Even if the indication of image-guided therapy in the treatment of GEP-NET liver metastases needs to be refined, such therapies allow for manageable invasive set of treatments able to address oligometastatic patients in liver, lung, and bones. These treatments applied locally will save the benefit and the toxicity of systemic therapy for more advanced stage of the disease.

In vitro investigation of ionic polysaccharide microspheres for simultaneous delivery of chemosensitizer and antineoplastic agent to multidrug-resistant cells

Insufficient intratumoral concentration of therapeutic agents and multidrug resistance are major factors responsible for failure of treatment of solid tumors. Simultaneous delivery of chemosensitizing and antineoplastic agents by microspheres could lead to enhanced chemotherapy of multidrug-resistant (MDR) tumors. Ionic polysaccharide microspheres derived from dextran were used to load chemosensitizers (e.g., verapamil) and anticancer drugs such as vinblastine. High drug loading was achieved for both a single agent and dual agents. The equilibrium drug loading was dependent on the ratio of the microspheres (MS) to the drug, as well as the relative affinity of the agents to the MS in the case of dual agents. The drug release from drug-MS involved hydration and swelling of the MS in addition to ion exchange. The effectiveness of MS-delivered chemosensitizers in the reversal of drug resistance was evaluated by measuring the uptake of [3H]vinblastine by MDR cells (CHRC5). The concomitant delivery of verapamil with vinblastine by the MS led to a 6-7-fold increase in the uptake of vinblastine, a level similar to the uptake obtained with free drug solutions. The results suggest that the antineoplastic and chemosensitizing agents were released effectively from the MS and the bioactivity of the chemosensitizer was preserved during the process.

Intratumoural administration of cisplatin in slow-release devices. I. Tumour response and toxicity

In this study we investigated the effect of the incorporation of cisplatin in slow-release systems on tumour response and animal toxicity after intratumoural (i.t.) administration. Solid slow-release rods with incorporated cisplatin were prepared either from starch or from three different polyether-hydrogel formulations. In vitro release rates from these rods were widely different. With the starch system, approximately 100% release was obtained in 2 h. For the hydrogel formulations, release was approximately 100% in 1 day for a formulation with 40% water uptake (T3), 45% within 4 days for a formulation with 14% water uptake (T2) and 8% within 4 days for a formulation with 4% water uptake (T1). The slow-release rods containing graded amounts of cisplatin were implanted i.t. in s.c. RIF1 murine tumours. The i.t. administration of cisplatin in starch rods did not reduce animal toxicity or increase tumour response relative to i.t. injections of cisplatin in solution. For the hydrogel rods, the tumour response and animal toxicity for a given dose of cisplatin decreased with decreasing release rate. Higher doses of cisplatin could therefore be delivered with the slower-releasing hydrogel formulations. The slowest-release hydrogel rods (T1) had very little effect on either tumour (growth delay) or host (animal weight loss), even at cisplatin doses 8 times that tolerated as an i.p. injection. The fast (T3)- and intermediate (T2)-release hydrogel rods resulted in dose dependent tumour growth delays that were longer than those obtained with i.p. or i.t. administration of cisplatin. The highest response, a tumour growth delay of 55 days, was obtained with the intermediate-release hydrogel rods (T2) at a cisplatin dose of 40 mg/kg. Analysis of tumour growth delay for a given level of toxicity indicated that the intermediate-release formulation (T2) was slightly better than the fast-release formulation (T3) and confirmed the therapeutic advantage of i.t. implants over systemic therapy.