Meeting the challenge of homogeneous boron targeting of heterogeneous tumors for effective Boron Neutron Capture Therapy (BNCT)

HEBER EM; TRIVILIN VA; NIGG D; ITOIZ ME; GONZALEZ BN; REBAGLIATI RJ; KREIMANN EL; SCHWINT AE

Takamatsu, Japón

Congreso; 12 International Congress on Neutron Capture Therapy; 2006

INTERNATIONAL SOCIETY FOR NEUTRON CAPTURE THERAPY

Purpose: BNCT is a tumor cell targeted radiation therapy. Inadequately boron targeted tumor populations jeopardize tumor control.  Meeting the to date unresolved challenge of homogeneous targeting of heterogeneous tumors with effective boron carriers would contribute to therapeutic efficacy. The aim of the present study was to evaluate the degree of variation in boron content delivered by boronophenylalanine (BPA), GB-10 (Na210B10H10) and the combined administration of (BPA + GB-10) in different portions of tumor, precancerous tissue around tumor and normal pouch tissue in the hamster cheek pouch oral cancer model. Methods: Samples (n = 4-6) of different areas of tumor, precancerous tissue and normal pouch tissue were taken from tumor-bearing hamsters, 3 hours post-administration of i.p. BPA (15.5 mg B/kg), or i.v. GB-10 (50 mg B/kg), or 3 h and 1.5 h post-administration respectively of i.v. GB-10 (34.5 mg B/kg) and sequential i.p. injections of BPA (total dose 31 mg B/kg) given jointly.  Boron content was evaluated by ICP-OES. The degree of homogeneity in boron targeting was assessed in terms of the coefficient of variation ([S.D./Mean] x100) of boron values. Statistical analysis of the results was performed by one-way ANOVA and the least significant difference test. Results: GB-10 and GB-10 plus BPA achieved respectively a statistically significant 1.8-fold and 3.3-fold increase in targeting homogeneity over BPA.  Conclusion: The combined boron compound administration protocol contributes to homogeneous targeting of heterogeneous tumors and would increase therapeutic efficacy of BNCT by exposing all tumor populations to neutron capture reactions in boron.