P18: DARATUMUMAB (D) PLUS BORTEZOMIB (V) AND DEXAMETHASONE (D) AS SALVAGE THERAPY FOR PATIENTS WITH REFRACTORY/RELAPSED MULTIPLE MYELOMA (RRMM): INITIAL FOLLOW-UP OF AN ITALIAN MULTICENTER RETROSPECTIVE CLINICAL EXPERIENCE BY "RETE EMATOLOGICA PUGLIESE". (5th April 2022)