Background: Angiogenesis may be vital to mCRPC. Previously, we had shown the potent anti−tumor activity of dual antiangiogenic therapy by combining thalidomide (T) and bevacizumab (B) with docetaxel (D) and prednisone (P) in mCRPC (Ning JCO 2010). We hypothesized that combining lenalidomide (L), an analogue of T, with B, D, and P would have a more favorable efficacy/toxicity profile. Methods: All patients (pts) had chemotherapy−naïve mCRPC. 3 pts received R 15 mg daily, 3 pts had 20 mg daily, and the rest had 25 mg daily for 14 days of every 21−day cycle (C). All pts received D 75 mg/m2 and B 15 mg/kg on day 1 with P 10 mg and enoxaparin daily throughout each C. Pegfilgrastim was given on day 2. PSA was assayed each C with imaging after C2 and then after every 3C. Results: 47 of the planned 51 pts have been enrolled. Median age was 66 (51−82), Gleason score 8 (5−10), on−study PSA 91.6 ng/ml (0.15−3520), pre−study PSA doubling time 1.43 months (0.52−6.73), number of Cs 14 (1−31), and PFS was 19.3 months as of this analysis. Among 45 pts who have completed ≥2 cycles, 39 (86.7%) and 30 (66.7%) had PSA declines of ≥50% and ≥75%, respectively. Of 29 pts with measurable disease there were 2 CR, 21 PR, and 6 SD (79.3% overall RR). 10/47 pts were taken off study for radiographic disease progression and 5/47 for other reasons. Grade ≥3 toxicities included neutropenia (24/47), anemia (9/47), thrombocytopenia (5/47), weight loss (1/47), hypertension (3/47), and febrile neutropenia (4/47). Other toxicities included perianal fistula (3/47), rectal fissure (1/47), myocardial infarction (1/47), and osteonecrosis of the jaw (ONJ) (16/47, 34.0%). At the time of diagnosis of ONJ, 9/16 pts were on bisphosphonates and 3/16 had used bisphosphonates previously. Although the incidence of ONJ was higher than the 18.3% reported by Ning, a recent study of carboplatin plus weekly docetaxel reported an incidence of 29.3%. Conclusions: Dual antiangiogenic therapy with, B and L, plus D and P was associated with high PSA (86.7%) and tumor (79.3%) responses with manageable toxicities. Further studies are underway to explore the high incidence of ONJ.