2Invictus Oncology Pvt. Ltd. New Delhi, India Ocular And Tissue Distribution Studies With Cabazitaxel For Its Utility In Ocular Tumors Rajeshkumar RK1, Bhattacharya S1, Aniruddha S2, Halder N1 and VelpandianT1 1Ocular Pharmacology & Pharmacy, Dr. R P centre, All India Institute of Medical Sciences (AIIMS), New Delhi, India 2Invictus Oncology Pvt. Ltd. New Delhi, India Introduction Retinoblastoma (RB) – Ocular tumor due to loss of RB gene function. Chemotherapy failure - associated with over expression of MDR1 (P-gp transporter). RB gene function loss - induces sensitization to taxanes as in Prostrate cancer (De Leeuw et al., 2015). Cabazitaxel (CBZ) -Taxane derivative with less affinity for P-gp; is effective in very low concentrations (Raguz et al., 2008). Earlier study showed the accumulation of CBZ in tumor tissue in prostrate tumor bearing mice model. RB could be effectively treated with CBZ as it sensitizes RB protein negative cells and has low affinity for P-gp-efflux pump. Vitreous, Plasma and Tissue samples analyzed by LC- MS/MS LC optimized Parameters Column: Dr. Maisch C8, 250x4.6mm, 3.5μm, 100 A° Mobile Phase: ACN: Water 0.1% FA (90:10) Objectives Table 1: Optimized source parameters To study ocular penetration of CBZ by quantifying it in vitreous after I.V. bolus injection. To know the bio-distribution of CBZ in organs and plasma levels after I.V. bolus injection. To ascertain and compare the level of clearance of CBZ between plasma and vitreous. Source parameter Values Curtain gas (CUR) 20 psi Ion spray voltage (IS) 5.5 KV CAD 10 Temperature 450°C GS1 and GS2 30 and 60 psi Experimental plan Mice 22 ± 1.8 grams divided into 2 groups (n=4). Both groups received CBZ 5mg/kg through tail vein injection and sacrificed at 4 and 24 hrs. Organs, plasma and vitreous collected and levels of CBZ was quantified by LC-MS/MS. Table 2: Transitions of compounds Conclusion Compounds Q1 (m/z) Q3 (m/z) Sulfadimithoxime (Internal Standard) 371 216 CBZ 836.6 555.3 CBZ – Na adduct 858.3 577.3 CBZ rapidly distributes into the organs within 4hrs of injection and is detectable even after 24hrs. This shows unlike tumors CBZ is not accumulating in organs. Plasma levels at 4hrs were 159±13ng/mL; undetectable after 24 hrs. In contrast to plasma – in vitreous CBZ reaches very less concentration after 4hrs and even after 24hrs very low concentration was detectable, this could be vitreous protein binding and poor clearance. Compared to other organs – CBZ levels in brain, vitreous is less and this could be due to the presence of barriers. Further in vitro and in vivo studies are in progress to asses utility of CBZ in Retinoblastoma models as it sensitizes RB protein negative cells. CBZ extraction protocol Tissue homogenate + ZnCl solution Vitreous, Plasma Results LLE – extraction (*MTBE) MTBE layer – Rotovac dried CBZ-Na Reconstituted with extraction solvent Calibration curve CBZ (3 to 1000ng) Analyzed by LC- ESI-MS/MS ( positive mode) References * MTBE - Methyl tert-butyl ether De Leeuw et al., 2015. Novel Actions of Next-Generation Taxanes Benefit Advanced Stages of Prostate Cancer. Clin Cancer. Res; 21(4); 795–807. Raguz S et al., 2008.Resistance to chemotherapy: new treatments and novel insights into an old problem. British Journal of Cancer (2008) 99, 387 – 391. Cabazitaxel 2015 Acknowledgement: Academic research grant from Invictus Oncology Pvt. Ltd. for conducting this study.