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Radiosensitization by Olaparib Eluting Nanospheres

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S Tangutoori

S Tangutoori1*, H Korideck2 , R Kumar1 , S Sridhar1 , G Makrigiorgos2 , R Cormack3 , (1) Northeastern University, Boston, MA, (2) Dana-Farber Cancer Institute, Boston, MA, (3) Harvard Medical School, Boston, MA


WE-G-BRE-8 Wednesday 4:30PM - 6:00PM Room: Ballroom E

Purpose:Permanent prostate brachytherapy often uses inert bio-absorbable spacers to achieve the desired geometric distribution of sources within the prostate. Transforming these spacers into implantable nanoplatforms for chemo-radiation therapy (INCeRT) provides a means of providing sustained in-situ release of radiosensitizers in the prostate to enhance the therapeutic ratio of the procedure. Olaparib, a PARP inhibitor, suppresses DNA repair processes present during low dose rate continuous irradiation. This work investigates the radiosensitizing/DNA damage repair inhibition by NanoOlaparib eluting nanospheres.

Methods:Human cell line PC3 (from ATCC), was maintained in F12-k medium supplemented with fetal bovine serum. Clonogenic assay kit (from Fischer Scientific) was used to fix and stain the cells to determine the long term effects of irradiation. Nanoparticle size and zeta potential of nanospheres were determined using a Zeta particle size analyzer. The incorporation of Olaparib in nanospheres was evaluated by HPLC. Irradiation was performed in a small animal irradiator operating at 220 KeV.The long term effects of radio-sensitization with olaparib and nanoolaparib was determined using the clonogenic assay at 2 Gy and 4 Gy doses. The cells were allowed to grow for around 10 doubling cycles, The colonies were fixed and stained using clonogenic assay kit. The excess stain was washed off using DI water and the images were taken using a digital camera.

Results: Radiosensitization studies were carried out in prostate cancer cell line, PC3 radiation at 0, 2 and 4Gy doses. Strongest dose response was observed with nanoolaparib treated cells compared to untreated cells.

Conclusion:A two stage drug release of drug eluting nanospheres from a biodegradable spacer has been suggested for sustained in-situ release of Olaparib to suppress DNA repair processes during prostate brachytherapy. The Olaparib eluting nanospheres had the same in-vitro radiosensitizing effect as free olaparib.

Funding Support, Disclosures, and Conflict of Interest: DOD 1R21CA16977501, A. David Mazzone Awards Program 2012PD164

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