A Prospective, Randomized, Phase III Study of Bortezomib, Melphalan, Prednisone and Thalidomide (VMPT) Versus Bortezomib, Melphalan and Prednisone (VMP) in Elderly Newly Diagnosed Myeloma Patients

Background: In newly diagnosed myeloma patients the combination of bortezomib with melphalan-prednisone (VMP) was superior to MP. In relapsed-refractory patients the 4 drug combination of bortezomib-melphalan-prednisone-thalidomide (VMPT) induced a high proportion of complete responses (CR).

Methods: Newly diagnosed myeloma patients (N=393) older than 65 years, from 58 centers in Italy, were randomly assigned to receive VMPT (N=193) or VMP (N=200). Initially, patients were treated with nine 6-week cycles of VMPT (bortezomib 1.3 mg/m² days 1,4,8,11,22,25,29,32 in cycles 1–4 and days 1,8,22,29 in cycles 5–9; melphalan 9 mg/m² days 1–4; prednisone 60 mg/m² days 1–4 and thalidomide 50 mg days 1–42, followed by bortezomib 1.3 mg/m² every 15 days and thalidomide 50 mg/day as maintenance) or VMP (bortezomib, melphalan and prednisone at the same doses and schedules previously described without maintenance). In March 2007, the protocol was amended: both VMPT and VMP schedules were changed to nine 5-week cycles and bortezomib schedule was modified to weekly administration (bortezomib 1.3 mg/m² days 1,8,15,22 in cycles 1–9). Primary end-point was progression-free survival (PFS).

Results: Patient characteristics were similar in both groups: median age was 71 years, 23% of patients were aged > 75 years. Patients who received at least 1 cycle were evaluated: 152 patients for VMPT (62 received bortezomib bi-weekly infusion and 90 weekly infusion) and 152 patients for VMP (62 received bortezomib bi-weekly infusion and 90 weekly infusion). Data were analyzed in intention-to-treat. The very good partial response (VGPR) rate was higher in the VMPT group (55% versus 42%, p=0.02), including a CR rate of 31% in the VMPT group and 16% in the VMP group (p=0.003). In the subgroup treated with weekly infusion of bortezomib, VGPR was 59% for VMPT and 37% for VMP (p=0.004), including 28% CR for VMPT and 10% for VMP (p=0.004). Subgroup analyses did not show any statistical difference between responses and either age, B2-microglobulin or chromosomal abnormalities, such as del13, t(4;14), t(14;16) and del17. After a median follow-up of 13.6 months, the 2-year PFS was 83.9% in the VMPT group and 75.7% in the VMP group (HR=0.73, 95% CI 0.38–1.42, p=0.35). In patients who received weekly infusion of bortezomib, the 2-year PFS was 86.8% in the VMPT group and 78.1% in the VMP group (HR=0.65, 95% CI 0.24–1.8, p=0.41). In patients who achieved CR after induction, the 2-year PFS was 100% for VMPT and 79% for VMP (p=0.02). The 3-year overall survival (OS) was 89.5% in the VMPT group and 88.7% in the VMP group (HR=1.02, 95% CI 0.43–2.46, p=0.96). The incidence of grade 3–4 adverse events (AEs) was similar in both groups. In the VMPT patients and in the VMP patients, the more frequent AEs were neutropenia (36% vs 31%), thrombocytopenia (20% vs 19%), peripheral neuropathy (18% vs 12%), infections (14% vs 10%), and gastrointestinal complications (7% vs 8%), respectively. The weekly infusion of bortezomib significantly decreased the incidence of grade 3–4 peripheral neuropathy (9% for VMPT and 3% for VMP).

Conclusion: VMPT is superior to VMP in terms of response rates. Longer follow-up is needed to assess their effects on PFS and OS. The weekly infusion of bortezomib significantly reduced the incidence of grade 3–4 peripheral neuropathy without influencing outcome.

Table. Complete responses, progression-free survival and peripheral neuropathy in all patients and in those who received weekly infusion of bortezomib