Boron Neutron Capture Therapy of Liver and Lung Coloncarcinoma Metastases: an in vitro Survival Study

The management of tumors disseminated in explantable organs by means of BNCT is particularly favourable. The possibilty to perfuse the isolated organ, withdrawing the residual boronated compound, and to expose it entirely to the neutron flux, let BNCT to better show its peculiarity i.e. selectively kill neoplastic 10B enriched cells sparing normal 10B lacking tissues. Being BNCT effectiveness tightly dependent on the amount of the endocellular boron at the time of neutron irradiation, the occurrence of the discarge of a fraction during the perfusion procedure is a questionable point in terms of therapeutic efficacy. In order to investigate the incidence of the endocellular boron loss, caused by the boronated compound deprivation, the boronophenylalanine (BPA) cell uptake and its washout were checked in vitro on the DHDK12TRb (DHD) rat coloncarcinoma cell line and in vivo, on BD-IX rats, affected by liver metastases induced by DHD cells injection, following BPA removal by the organ perfusion. The dose-dependent cell survival was studied on the same cell line. Results on the DHD cells show a time and concentration dependent boron accumulation capability. Cell harvesting as like as time and temperature of permanence in boron deprived medium influence boron loss, that can reach substantial levels. Nevertheless the retained intracellular fraction results in a TD50 for an absorbed dose of 0,29 Gy. In vivo data of ongoing studies show more favourable cellular behaviour in terms of retained boronated compound suggesting that the organ perfusion cannot invalidate the BNCT therapeutic efficacy.