8517 Background: Three-drug combinations with lenalidomide (Revlimid, Rev) and bortezomib (Velcade, Vel) are highly active in previously untreated multiple myeloma (MM). Among the most active are RVD (Revlimid, Velcade, Dexamethasone) and VDD (Velcade, Doxil, Dexamethasone) with ≥ PR rate of 100% and 93%, and a CR/nCR rate of 44% and 40%, respectively. Pre-clinical evaluations suggest that adding pegylated liposomal doxorubicin hydrochloride (Doxil, Dox) to RVD (RVDD) may have higher activity. This phase I/II study was designed to determine the maximum tolerated dose (MTD) of RVDD, assess safety and evaluate efficacy of this 4-drug regimen in newly diagnosed MM. Methods: Four dose levels are being evaluated: Rev 15–25 mg (days 1–14), Vel 1.3 mg/m2 (days 1, 4, 8, 11), dexamethasone (Dex) 20/10 mg (cycles 1–4/5–8; days of and after Vel), Dox 20 and 30 mg/m2 (day 4), with dose assignment for patients (pts) according to the TITE-CRM algorithm. Eight 21-day cycles are planned with 38 pts to be treated at the MTD in phase II. Pts who achieve ≥ PR can proceed to autologus stem cell transplant (ASCT) after ≥ 4 cycles, while all others receive 21-day maintenance cycles with Rev (days 1–14), Vel (day 1 and 8), and Dex (days of and after Vel) at the doses tolerated by the end of initial treatment. Results: The study has enrolled 23 pts to date. Four pts received level 1 (Rev/Dox 15/20), 11 pts level 2 (Rev/Dox 20/20, and 8 pts level 3 (Rev/Dox 25/20). Nineteen pts are evaluable for toxicity after completion of a median of 4 cycles (range 1–8). Two pts developed DLT at dose level 2, consisting of grade (G) 3 asymptomatic neutropenia and G3 elevation of transaminase. The MTD has not been reached. Overall, toxicities have been manageable with no additional G3 hematologic events. There have been 4 additional G3 non-hematologic events including one case each of pneumonia, DVT, fatigue, and hypotension. After a median of 12 (range 3–24) weeks of treatment, preliminary response rates by modified EBMT/UC in 19 evaluable pts are: 95% ≥ PR, 47% ≥ VGPR, 26% CR/nCR. Conclusions: RVDD is well tolerated in newly diagnosed MM and appears highly active with an overall response (≥ PR) of 95%. Accrual is ongoing, with updated toxicity and efficacy data to be presented at the meeting. [Table: see text]