Chemotherapy plus Bevacizumab combination in mCRC patients results in dynamic changes in plasma cytokines, which is associated with better disease control and longer PFS. These new findings support continuing studying AS as a potential marker of angiogenesis inhibitor effectiveness.

4040 Background: Nab-paclitaxel in combination with gemcitabine has shown interesting clinical activity in patients with advanced pancreatic cancer (PDA) likely related to its ability to eliminate pancreas cancer stroma. In this study we explore clinical and pathological effects of the combination in patients with operable PDA. Methods: Patients with resectable o borderline resectable pancreatic cancer were treated with gemcitabine(1000mg/m2 days 1, 8 and 15) and nab-paclitaxel(125mg/m2 days 1, 8 and 15) for two cycles prior to surgery. Response was assessed by FDG-PET, CA199 levels and elastography, an EUS-based non invasive assessment of tumor stroma. Results: 16 patients were included into the study. 2 patients (12.5%) showed a progression disease (both with hepatic metastases) and were not operated. Median value for PET SUVmax decreased from 7,1 pre-treatment to 4,6 post-treatment(p=0.004), including 7(50%) of patients with a partial metabolic response and the mean CA199 decreased from 2654 to 52(p=0.02) with 43% patients having a more that 75 % decrement in tumor marker. The elastography ratio value diminished from 36 pre-treatment to 18 post-treatment(p=0.003) and correlated with improvement in SUVmax(p=0.04) and CA199 response(p=0,07). Grade 3-4 toxicities were neutropenia in 18% (none febrile neutropenia), thrombocytopenia in 12.5 and 6.2% transaminase elevation. So far 9 patients have been operated and in 8(89%) a complete resection (R0) was achieved. 1 patient had a complete pathological response and 4 patients had near complete responses with only a few(< 5%) residual tumor. In-depth analysis of stromal composition after treatment showed, compared to a series of 10 cases untreated and treated with conventional chemoradiation, decreased myofibroblast content, increase vessel density and distorted collagen fibers. Conclusions: Neoadjuvant treatment with gemcitabine plus nab-paclitaxel is feasible and results in significant clinical activity. Non-invasive elastography appears and attractive method to monitor tumor response. The rate of pathological responses and R0 resections in substantial for this setting. Biological studies of resected specimens show unique effects in tumor stroma.

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e15735 Background: We aimed to evaluate the clinical relevance of RFS after local PDA resection as a prognostic factor in terms of SAR and OS. Methods: Patients diagnosed with local PDA who had undergone surgical resection in 4 hospitals from Spain were identified. Disease location, demographic, pathologic, treatment during recurrence and mortality information was retrospectively collected. RFS was measured from date of surgery until recurrence and censored at death or last follow-up. SAR was measured from relapse, until death or last follow-up. We defined patients presenting an RFS value of 6 months or more, or less than 6 months as High-RFS and Low-RFS respectively. Results: Of 93 patients with resected PDA, 51 (54.8%) were male and 42 (45.2%) female. The median age was 65.2 years. 62 (66.7%) tumors were localized in the head. There were 5 (5.4%), 17 (18.3%) and 69 (74.1%) stage I, II and III respectively. 53 (57%) patients had undergone cephalic (Whipple), 20 (21.5%) distal and 20 (21,5%) total pancreatectomy. 48 (51.6%) patients received radiotherapy and 86 (92.5%) received chemotherapy in the neoadjuvant and/or adjuvant setting. Median RFS was 12.3 months. In the metastatic setting, the most frequent chemotherapy combination was gemcitabine plus nab-paclitaxel. 43(46,2%) of patients received second line chemotherapy. Median OS and median SAR were 25,9 and 10,1 months respectively. Kaplan-Meier survival analysis showed that PDA cancer patients with Low-RFS have a poorer clinical outcome than those with High-RFS (median OS 48.26 months, CI 95% 39,3-57,1 for High-RFS; 19.2 months CI 95% 15.7-22-8 for Low-RFS; p = 0.0001). On multivariate Cox regression analysis, age, initial stage I-II, adjuvant chemotherapy utilization and High-RFS were independent prognostic factors for OS and SAR rate. Conclusions: RFS was strongly correlated and discriminated PDA patients with better SAR and OS from the poorer prognosis patients in the ulterior metastatic setting. Prospective studies are needed to confirm this finding.