Bevacizumab As Maintenance Therapy (Mbev) In Metastatic Breast Cancer (Mbc).

e22149 Background: Preclinical models suggest that the anti-VEGF may improve the efficacy of anti-estrogen therapies in Hormonal Receptor positive (HR+) breast cancer, but there is lack of informations about the maintenance therapy with Bev (mBev) and Hormonal Therapy (HT). Methods: sixty-one pts with HER-2 negative MBC were treated, at our institution from 2007, with Bev+Taxanes (BT) as 1stline chemotherapy and with HT in HR+ pts as maintenance therapy. Primary endpoints were the evaluation of Progression Free Survival (PFS) and Overall Survival (OS). Secondary endpoint was the safety with HT in HR+ pts. Results: Hormonal status was positive in 52/61 (85%). Antracyclines were administered as adjuvant therapy in 26 pts (42%), antra+tax in 26 (42%) pts, no adjuvant therapy in 9 pts (14%). At the time of first relapse, median age was 50 y/o (range 33-72). First line HT was given to 12 pts. Metastatic sites were only bone in 20 pts (32%), visceral in 15 pts (25%), bone + visceral in 19 pts (31%), lymph nodes in 7 pts (11%). ECOG PS was 0 in 56 pts and 1 in 5. Median number of cycles of BT was 7 (1-14). All pts were evaluated for PFS and OS and 45 pts were evaluated for objective response: complete response (CR) was achieved in 5/45 pts (11%) (duration 12 months), partial response (PR) in 34/45 pts (75%) (duration 6-7 months), stable disease (SD) in 6/45 pts (14%) (6 months). After the assessment of the response, 34/61 pts received maintenance Bev (mBev); among this group, 24/34 pts with HR+ were also treated with HT until disease progression. The median number of cycles of mBev was 8 (1-42). Median PFS was 13.5 months (95%CI: 10.2-18.2) and median OS was 36 months (95%CI: 22-51). The BT regimen was well tolerated: 2 pts experienced cardiotoxicity with a reduction in left ventricular ejection fraction (LVEF); the most common side effects were hypertension (grade 1 in 11 pts e grade 2 in 16 pts), bleeding in 8 pts, proteinuria in 7 pts (grade 1 in 5 pts and grade 2 in 2 pts). Conclusions: Hormonalmaintenance and Bev can extend the overall benefit of therapy and it is well tolerated and associated with long-term clinical outcome. Our results are encouraging for prolonging Bev in association with HT as maintenance therapy until disease progression.