A Phase II Study of Sequential Velcade/Thalidomide/ Dexamethasone (VTD) as Maintenance Therapy Post Single Autologous Peripheral Stem Cell (PSCT) in Patients with Multiple Myeloma.

Abstract 3403 Poster Board III-291 Autologous PSCT remains standard treatment in younger patients (pts) with multiple myeloma. However, relapse is the major cause of treatment failure. Several studies have reported improved progression-free survival (PFS) and possibly overall survival with thalidomide alone or in combination with steroid and chemotherapy as maintenance/consolidation therapy post autologous PSCT. We performed a phase II study investigating the role of sequential velcade/thalidomide/dexamethasone (VTD) as maintenance therapy post single PSCT. The objectives were to examine the toxicities of prolonged course of sequential VTD, CR rate, PFS and overall survival following single autologous PSCT. Within 4-8 weeks of autologous PSCT using melphalan 200mg/m2, pts received weekly velcade (vel) at 1.3mg/m2 /wk x 3 weeks with 1 week rest and dexamethasone (dex) at 40mg/d x 4 d for 6 months, followed by thalidomide (thal) at 50 -200mg/d and dexamethasone (dex) at 40mg/dx4 d for 6 more months. Single agent thalidomide was then continued until disease progression. Twenty-eight pts have been enrolled. Median age is 54 years (29-66). Median time from diagnosis is 7.9 mo. (4.2 – 145). Disease stage at diagnosis; by Salmon-Durie (II/III 6/22) and by ISS (I/II/III 11/9/7/missing data in 1 pt). Pts received induction treatment with thal/dex (14), velcade based (15) and revlimid based regimens (7). Median B2M at enrollment is 1.75 mg/L (1.14 -5.3). Disease status at enrollment; CR (7) VGPR (9), PR (11), SD (1). Three pts have chromosome 13 abnormalities (1 pt by karyotype and 2 pts by FISH). Results: All pts have undergone transplant. Four pts were unable to start planned maintenance therapy due to development of grade II or more neuro toxicities (3), and persistent thrombocytopenia (1) after PSCT. Twenty-four pts started maintenance vel/dex within 4-8 weeks of PSCT. Nine pts have completed 6 months of vel/dex. Two pts stopped vel/dex because of low WBC (1) or PN (1). With a median F/U of 5.2 mo. (1.2 -17.3) nine of 28 pts (33%) have achieved CR post PSCT and six out of 11 evaluable pts (55%) have achieved CR after vel/dex. Six out of 9 pts (66%) who have completed 6 mo. of vel/dex achieved CR. Two out of 9 pts (22%) have upgraded their response with vel/dex. Four pts have completed 6 month of thal/dex and are beyond 1 year post PSCT. Two out of 4 pts remain in CR at one year post PSCT. One pt is in PR and 1 pt has progressed. Two pts could not complete thal/dex phase of therapy because of relapse (1) and grade III GI toxicity (1). Three pts have relapsed of whom 1 pt died of relapsed myeloma (leptomeningeal disease). No grade IV toxicity has been noted. Grade III toxicities have occurred in 4 pts; low platelet (1), fatigue (1), mood alteration (1), GI (severe constipation) (1). Thirteen pts have peripheral neuropathy (PN). Ten pts had PN grade I at enrollment. Only 3 pts have developed PN on the study and all are grade I - II. Median velcade dose is 1.3 mg /m2/wk and thalidomide dose is 100mg /d. Conclusion: Prolonged sequential velcade/thalidomide/dexamethasone maintenance therapy post single autologous PSCT is well tolerated with no severe peripheral neuropathy. Fifty-five percent of pts have achieved CR and 22% have upgraded their response after six months of velcade/dexamethasone therapy suggesting this is an active and well tolerated maintenance strategy post PSCT. Disclosures: Sahebi:Celgene: Honoraria; Millennium Pharmaceutical: Research Funding. Off Label Use: The use of bortezomib(Velcade)in combination with thalidomide and dexamethasone is investigated as maintenance therapy post autologuous stem cell transplant in patients with multiple myeloma.