Automated quantitative analysis of AKT/mTOR pathway in patients treated with nanoparticle albumin-bound paclitaxel (ABI-007, Abraxane) and (sirolimus)Rapamycin

14670 Background: pp70S6K inhibition and pAkt up-regulation has been reported with mTOR inhibitors. We evaluated changes in these targets following rapamycin (R) therapy by Automated Quantitative Analysis (AQUA), a novel technology that uses molecular methods to define subcellular compartments, and then quantifies the amount of protein expressed within the compartment by co-localization, permitting preservation of tissue morphology while quantifying protein expression in paraffin-embedded tissue. Methods: Cohorts of 3–6 patients (pts) with advanced solid tumors were enrolled and treated. Escalating oral dose of R (5–40 mg) was administered on days -7, 2, 9 and 16 and intravenous fixed dose of Abraxane (100 mg/m2)on days -14, 1, 8, and 15 of a 28 day cycle. Tumor tissue was collected by core biopsies from consenting pts for measurement of pre and post day -7 R therapy of p70S6K, pp 70S6K, Akt, pAkt by AQUA. Primary antibodies used to define tumor compartment included mouse monoclonal Cytokeratin AE1/AE3 (M3515, Dako Corporation, Carpinteria, CA) or wide-spectrum screening rabbit anti-cow cytokeratin antibody (Dako Z0622) each at 1:100. Target antibodies were incubated overnight at 4ºC and included Akt ((2H10): cat#2967, mouse mAb, used 1:700), pAkt (736E11-Ser473) used at 1:100), and p706SK (49D7) used at 1:200 and pp70S6K (1A5- Thr389) used at 1:100. Results: To date 16 pts with have been treated in 4 cohorts as follows; Cohort 1 (5/100, n = 3), Cohort 2 (10/100, n = 6), Cohort 3 (20/100, n = 3), Cohort 4 (40/100, n =4). To date, pre and post therapy tissue sample was collectied in 4 patients (1 lung/cohort 1, 1 sarcoma/cohort 1, 1 melanoma/cohort 3, and 1 endometrial/cohort 4). We found a decrease in the pp70S6K and pAkt in post therapy samples from baseline in 4 patients, and a decrease in the p70S6K in 3 of 4 patients. Pre and post therapy Akt analysis is available on 2 of the 4 patients (cohort 3 and 4), and showed an increase from baseline in both. Conclusions: Consistent with prior reports, we found a decrease in the pp70S6K post rapamycin therapy. Although we found an increase in total Akt in the 2 patients, there was a decrease in pAkt in 4 patients. AQUA analysis of molecular targets of AKT/mTOR pathway is feasible. The MTD has not yet been reached and enrollment continues, and additional samples will be collected. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Abraxis Oncology, HistoRx HistoRx Abraxis Oncology Abraxis Oncology