Bortezomib, Melphalan, Prednisone and Thalidomide Followed by Maintenance with Bortezomib and Thalidomide (VMPT-VT) for Initial Treatment of Elderly Multiple Myeloma Patients: Updated Follow-up and Impact of Prognostic Factors

The combination of bortezomib-melphalan-prednisone (VMP) is a new standard of care for elderly newly diagnosed multiple myeloma. This phase 3 study compared the 4 drug combination bortezomib-melphalan-prednisone-thalidomide followed by maintenance bortezomib-thalidomide (VMPT-VT) with VMP alone.

Patients (N=511) older than 65 years were randomized to receive nine 6-week cycles of VMPT-VT (N=254; induction: bortezomib 1.3 mg/m², d 1, 4, 8, 11, 22, 25, 29, 32, cycles 1–4, d 1, 8, 22, 29, cycles 5–9; melphalan 9 mg/m² d 1–4, prednisone 60 mg/m², d 1–4, thalidomide 50 mg d 1–42; maintenance: bortezomib 1.3 mg/m² every 14 days and thalidomide 50 mg/day) or VMP (N=257) alone. In March 2007, the protocol was amended: both VMPT-VT and VMP induction schedules were changed to nine 5-week cycles and bortezomib schedule was modified to weekly administration (1.3 mg/m² d 1,8,15,22, all cycles). The primary end point was progression-free survival (PFS).

All patients have been evaluated in intention-to-treat. Patient characteristics were similar in both groups, median age was 71 years. The response rates were superior in the VMPT-VT group with a complete remission (CR) rate of 38% vs 24% (p=0.0008). After a median follow-up of 26.1 months, the 3-year PFS were 55% in patients receiving VMPT-VT and 38% in those receiving VMP (HR 0.65, 95% CI 0.49–0.85, P=0.002, Table). The 3-year time-to-next-therapy were 69% with VMPT-VT and 55% with VMP (HR 0.60, 95% CI 0.42–0.85, P=0.004). The 3-year overall survival was 86% with VMPT-VT and 84% with VMP (HR 0.88, 95% CI 0.53–1.45, P=0.62). The achievement of CR was a strong predictive factor of longer PFS in both groups (P=0.0001): in VMPT-VT arm, 3-year PFS was 66% in patients who obtained CR and 47% in those achieving PR; in VMP arm, it was 70% and 30%, respectively. The PFS benefit of VMPT-VT was seen consistently across different subgroups defined by creatinine clearance, LDH and bortezomib schedule; by contrast, in patients older than 75 years (HR 0.87; 95% CI 0.54–1.43, P=0.59) and in those at increased risk of disease progression, defined as presence of cytogenetic abnormalities [t(4;14) or t(14;16) or del17p] and ISS 3 (HR 1.35; 95% CI 0.45–4.06, P=0.60), VMPT-VT seemed not to add any significant PFS advantage to VMP. Grade 3–4 neutropenia (38% vs. 28%, p=0.02), cardiological events (10% vs. 5%, p=0.04) and thromboembolic events (5% vs. 2%, p=0.08) were more frequent among patients assigned to the VMPT-VT group; treatment-related deaths were 4% with VMPT-VT and 3% with VMP. In both groups, the once-weekly infusion of bortezomib significantly reduced the incidence of severe sensory peripheral neuropathy from 16% to 3% (p<0.0001). One hundred and forty-nine VMPT-VT patients were assessable for maintenance treatment. After a median duration of maintenance of 14.4 months, the PR rate was 90%, including 45% CR. The 1-year landmark analysis of PFS in patients completing the 9 induction cycles, showed a 2-year PFS of 63% in the VMPT-VT group and 40% in the VMP group, demonstrating that maintenance with VT reduced the risk of disease progression of 51% (HR 0.49, 95% CI 0.33–0.72, p=0.0003, Figure). This advantage was less evident in patients older than 75 years (HR 0.97, 95% CI 0.52–1.78, P=0.91) and in those with high-risk of disease progression, defined as presence of cytogenetic abnormalities and ISS 3 (HR 1.31, 95% CI 0.22–7.85, p=0.77). Continuous therapy with VT had favourable safety profile: 3% of patients experienced grade 3–4 hematological toxicity, 5% grade 3–4 peripheral neuropathy and 7% discontinued due to adverse events.

In summary the current results indicate that: 1. VMPT-VT prolonged PFS with an unprecedented 3-year PFS of 55% in elderly patients; 2. once-weekly infusion of bortezomib improved safety without affecting outcome; 3. higher dose-intensity regimens seemed to be less effective in frail patients (≥ 75 years) and 4. maintenance therapy with VT further improved PFS with a good safety profile.

Palumbo:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees. Bringhen:Celgene: Honoraria; Janssen-Cilag: Honoraria. Patriarca:Celgene: Honoraria; Janssen Cilag: Honoraria; Roche: Honoraria; Merck: Membership on an entity's Board of Directors or advisory committees. Guglielmelli:Celgene: Honoraria; Janssen Cilag: Honoraria. Petrucci:Celgene: Honoraria; Janssen Cilag: Honoraria. Musto:Celgene: Honoraria; Janssen Cilag: Honoraria. Boccadoro:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen Cilag: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.