Bortezomib, Doxorubicin and Dexamethasone (PAD) Prior to High-Dose Melphalan / Autologous Stem Cell Transplantation for Newly Diagnosed Plasma Cell Dycrasias.

Abstract 4960

High-dose melphalan (HDM) with autologous stem cell transplantation (ASCT) is the standard of care for myeloma (MM) patients aged < 70 years. Achievement of complete/very good partial response (CR/VGPR) is prognostic for improvement overall survival (OS) and use of more effective induction regimens prior to HDT-ASCT may result in improvement post-transplant responses. We performed a retrospective analysis of newly MM pts treated with bortezomib-doxorubicin-dexamethasone (PAD) prior HDM-ASCT.

From October 2005 and July 2008, 20 previously untreated MM pts were enrolled: median age was 56 years (range 44-68), 50% male. Of them, 3 had primary plasma cell leukemia (pPCL), 5 were on dialysis for MM-related renal impairment. Cytogenetic was available for 9: 2 (1 pPCL and 1 MM) had t(4;14). PAD included Bortezomib (1.3 mg/m² on D1, 4, 8, 11), doxorubicin (9mg/m² D1-D4), dexametasone (40mg D1-D4): 4 cycles (13 pts), 3 (6 pts), and 2 (1). Response rates after PAD were CR 10%, VGPR 50%, PR 20%, SD 10%. 1 pt died of pulmonary hypertension related to MM after 2 cycles of PAD. Neurologic toxicity ' grade 2 was observed in 3 pts and DVT in 1.

Following induction, 17 pts underwent PBSC harvesting: cyclopsphamide + G-CSF (8), G-CSF only (10). Median yields were 7.9 10⁶ CD34/kg (6-10.5). 17 pts underwent HDM: 200 mg/m² (12 pts) and 140 mg/m² (5 pts with renal insufficiency, including 3 on dialysis), followed with ASCT. 1 pt benefited a double HDM/ASCT and 1 (pPCL) a mini-allotransplant 3 monts after. There was no treatment related mortality.

Response rates 3 months post ASCT (17 pts) were: CR 18%, VGPR 70%, PR 6%, SD 6%. 1 SD post PAD obtained VGPR after Thal-Dex had double HDM/ASCT with CR.

With a median follow-up of 23 months (7-34), median OS has not been reached and 1-year survival was 95%. At the reference date of July 2009 85% are alive, 5 pts relapsed: median 12 months (6-14), EFS was 31 months and 2 pts with t(4;14) are alive in CR/VGPR at 23 and 31 months

Concerning the 3 pPCL pts: 1 remained alive in CR 12 months post allo-transplant (follow-up 23 months), 1 was in CR post PAD and relapsed 11 months post HDM/ASCT (survival = 20 months) and 1 is alive at 12 months from diagnosis with a refractory disease. Dialysis could be interrupted for 3 pts in CR/VGPR: 1 after PAD, 2 after ASCT..

In conclusion, according to previously published results (Popat R, British Journal of Haematology 2008), PAD regimen in preparation of HDM/ASCT is safe and highly active in MM patients. Moreover, prolonged remissions and survivals could be obtained in pPCL patients and reversal of severe renal insufficiency observed.