A Phase III PETHEMA/GEM Study of Induction Therapy Prior Autologous Stem Cell Transplantation (ASCT) In Multiple Myeloma: Superiority of VTD (Bortezomib/Thalidomide/Dexamethasone) Over TD and VBMCP/VBAD Plus Bortezomib

In April 2006, the Spanish Myeloma Group (PETHEMA/GEM) activated a randomized phase III trial comparing TD vs. VTD vs. VBMCP/VBAD/Bortezomib (VBMCP/VBAD/B) in patients 65 years-old or younger with newly diagnosed symptomatic MM followed by ASCT with MEL-200.

response rate after induction and after ASCT and time to progression.

TD consisted of thalidomide 200 mg daily (escalating doses in the first cycle) and dexamethasone 40 mg on days 1–4 and 9–12 at 4-week intervals for 6 cycles. The VTD regimen was identical to TD plus bortezomib 1.3 mg/m² on days 1,4,8,11 of each cycle. Combination chemotherapy plus bortezomib consisted of 4 cycles of VBMCP/VBAD on an alternating basis followed by 2 cycles of bortezomib (1.3 mg/m² on days 1,4,8, and 11 every 3 weeks). The duration of the induction therapy was 24 weeks in all arms. From April 6, 2006 to August 5, 2009 the 390 planned patients entered the study. Four patients failed the eligibility criteria. 386 patients (median age: 56 yrs; M: 207, F: 179; IgG: 233, IgA: 85, light chain: 57, IgD: 9, Ig M: 2) were analyzed. The stage according to the ISS was I in 147 patients, II in 160, III in 75 and unknown in 4 and 66 patients (17%) had extramedullary soft-tissue plasmacytomas (EMP). Seventy out of the 330 patients (21%) with cytogenetic studies had high-risk cytogenetics (t(4;14), t(14;16), and/or 17p deletion). One-hundred and thirty patients were allocated to VTD, 127 to TD and 129 to VBMCP/VBAD/B. Prognostic factors, including cytogenetics, were similar in the 3 arms. Response, survival and toxicity were evaluated on an intention-to-treat basis. Responses reported by investigators were centrally reassessed.

The IFE negative CR rate was significantly higher with VTD (35%) compared to TD (14%) and VBMCP/VBAD/B (22%) (p=0.0001 and p=0.01, respectively). The progressive disease (PD) rate during induction was significantly lower with VTD than with TD (7% vs. 23%, p=0.001). In patiens with high-risk cytogenetics, the CR rate was significantly greater with VTD when compared with TD (35% vs. 0%, p=0.002) and with VBMCP/VBAD/B (35% vs. 22%, p=0.02). The CR rate to VTD in patients with 17p deletion was 58% while none of the patients with this cytogenetic abnormality responded to TD or to VBMVP/VBAD/B (p=0.03 and p=0.02, respectively). Of interest, the CR rate in patients with t(11;14) was significantly lower than in patients lacking this abnormality (11% vs. 27%, p=0.01). This low CR rate in patients with t(11;14) was similar in the 3 arms. In the overall series, PD was significantly higher in patients with EMP (24% vs. 11%, p=0.01) with a significantly higher PD rate for TD as compared to VTD (40% vs. 12%, p=0.02). The incidence of thrombotic events was 2%, 6% and 5% for VTD, TD and VBMCP/VBAD/B, respectively (p=NS). The frequency of grade ≥ 3 peripheral neuropathy was 12% with VTD compared to 1% in both the TD and the VBMCP/VBAD/B arms (p= 0.0002). Treatment was discontinued due to toxicity en 16 patients (VTD:9, TD:4, VBMCP/VBAD/B:3). Nine patients died during the induction period (3 in each arm). On an intention to treat basis, the post-ASCT CR rate was higher in the VTD arm compared with TD (46% vs. 24%, p=0.004) and VBMCP/VBAD/B (46% vs. 38%, p=0.1). The estimated overall survival (OS) at 4 years was 76% with no significant differences among the 3 arms. After a median follow-up of 27 months, the progression-free survival (PFS) was not reached with VTD while it was 27 and 38 months with TD and VBMCP/VBAD/B, respectively (p=0.006). In the overall series, patients with high-risk cytogenetics had a significantly shorter OS (p=0.00007) and PFS (p=0.004). In addition, when compared with the good-risk group, patients with high-risk cytogenetics showed a trend towards a shorter PFS either after induction with VTD (median not reached vs. 17 months, p=0.05) and with TD (median 28 vs. 15 months, p=0.09).

Induction with VTD resulted in a significantly higher CR rate in both the overall series and in patients with high-risk cytogenetics. The post-ASCT CR rate was also significantly higher with VTD than with TD and there was a trend when compared with VBMCP/VBAD/B. Finally, VTD resulted in a significantly longer PFS. However, longer follow-up is required to establish whether or not VTD will overcome the poor prognosis of patients with high-risk cytogenetics.

Rosiñol:Janssen-Cilag: Honoraria; Celgene: Honoraria. Off Label Use: Bortezomib and Thalidomide are not approve for first line in Spain. Cibeira:Janssen-Cilag: Honoraria; Celgene: Honoraria. Mateos:Janssen-Cilag: Honoraria; Celgene: Honoraria. Oriol:Janssen-Cilag: Honoraria; Celgene: Honoraria. García-Laraña:Janssen-Cilag: Honoraria; Celgene: Honoraria. De La Rubia:Janssen-Cilag: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Sureda:Janssen-Cilag: Honoraria; Celgene: Honoraria. Díaz-Mediavilla:Janssen-Cilag: Honoraria. Alegre:Janssen-Cilag: Honoraria; Celgene: Honoraria. Lahuerta:Janssen-Cilag: Honoraria; Celgene: Honoraria. San Miguel:Janssen-Cilag: Honoraria; Celgene: Honoraria, Speakers Bureau. Blade:Janssen-Cilag: Honoraria, Research Funding; Celgene: Honoraria, Research Funding.