Implementation of beta radiation emitting devices (BE) as a complementary tool to Boron Neutron Capture Therapy (BNCT) for the treatment of superficial cancer

NIEVAS S; CARPANO M,; PERALTA T; JUVENAL G; LONGHINO J; DAGROSA MA

Mar del Plata

Congreso; LXIV Reunion anual de la sociedad argentina de investigacion clinica; 2019

Sociedad Argentina de Investigacion Clinica

Introduction: The BNCT clinical trials in Argentina started in 2015 after changes in the beam in the RA-6 reactor. BNCT is based on the nuclear reaction 10B (n, α) 7Li. Due to the characteristics of the neutron beam, the maximum dose is not on the surface of the tumor, but at 1 cm deep. Some materials (like Rhodium, Indium and Silver) have a high effective neutron capture section, rapid decay activation products and high energy beta particles emission. Since beta radiation has a short range of tissue penetration, these devices called Beta Enhancers (BE) can be used to compensate for the BNCT surface dose gradient or even to significantly increase it. In this work we analyze in vivo the therapeutic efficacy of the different types of BE and the advantages of adding them to BNCT therapy. Materials and Methods: NIH nude mice were implanted with cells from the HT-29 colon cancer human cell line, developing tumors at day 15. The animals were divided into 5 groups Control, BNCT, BNCT-Rh, BNCT-Ag and BNCT-In. The mice were irradiated 45 minutes with a neutron flux of 4.96x108n/cm2sec. Results: Animal monitoring after irradiation does not show any signs of radiotoxicity. Tumor growth decreased in all the groups treated by BNCT. Histological studies had a correlation between the area of tumor necrosis and the total physical dose absorbed (between 7 and 9Gy). A smaller amount of cancer stem cells (CSC) CD133+ was observed in all the BNCT groups compared with the control (p˂0.01) after three weeks of treatment. Among the BNCT groups, the persistence of CSC was lower in the BNCT-Rh group. Conclusions: All the BNCT treatments showed an efficacy in controlling tumor growth post irradiation during a month. However the BE Rh exhibited a smaller number of CSC CD133+ at 21 days post treatment, indicating an advantage over the others treatments.