A Phase III PETHEMA/GEM Randomized Trial of Postransplant (ASCT) Maintenance in Multiple Myeloma: Superiority of Bortezomib/Thalidomide Compared with Thalidomide and Alfa-2b Interferon,

In April 2006, the Spanish Myeloma Group (PETHEMA/GEM) activated a randomized phase III trial comparing induction with TD vs. VTD vs. VBMCP/VBAD/Bortezomib (VBMCP/VBAD/B) in patients 65 years-old or younger with newly diagnosed symptomatic MM and ASCT with MEL-200 followed by maintenance with thalidomide/bortezomib (TV) vs. thalidomide (T) vs. alfa-2b-interferon (alfa2-IFN). Primary end points : response rate after induction and after ASCT and time to progression.

The maintenance program consisted of TV (thalidomide 100 mg daily plus one cycle of bortezomib-1.3 mg/m2 on days 1, 4, 8 and 11 every 3 months) versus T (single agent thalidomide at a dose of 100 mg daily) versus alfa2-IFN (subcutaneous alfa2b-IFN at a dose of 3 MU three times per week). The planned maintenance duration was three years or until disease progression or toxicity. From February 1, 2007 to January 27, 2011 266 patients were randomized to maintenance therapy (TV:90; T: 89, alfa2-IFN: 87). Response and survival were evaluated on an intention-to-treat basis. Responses and progressions reported by the investigators were centrally reassessed.

the patient's characteristics at diagnosis such as age, ISS stage, cytogenetics and presence of extramedullary plasmacytomas as well as induction regimen (VTD, TD and VBMCP/VBAD/Bortezomib) and diagnosis-randomization interval were similarly distributed among the 3 arms. The response status at the time of randomization after ASCT was CR: 51%, VGPR: 23%, PR: 24% and SD: 2% and was well balanced in the three groups. The CR rate with maintenance was improved by 23% with TV, 11% with T and 19% with alfa2-IFN (p=NS). After a median follow-up of 24 months, the PFS was significantly longer with TV compared with T and alfa2-IFN (PFS at 2 yrs: 78% vs. 63% vs. 49%, p=0.01). However, OS was not significantly different among the 3 arms. Grade 3 and 4 hematological toxicity was similar (22.2% vs. 16% vs. 21.8%). No peripheral neuropathy (PN) was observed with alfa2-IFN being its frequency similar with TV (12.2%) and T (10.1%). No grade IV PN was observed. Dose reductions for TV, T and alfa2-IFN were required in 33.3%, 33.7% and 19.5% of the patients, respectively. The discontinuation rate due to toxicity was significantly higher with thalidomide compared with TV (30.3% vs. 15.6%, p= 0.08) and with alfa2-IFN (30.3% vs. 18.3%, p= 0.17).

the addition of bortezomib to thalidomide maintenance resulted in a significantly longer PFS when compared with thalidomide alone or with IFN with no increased toxicity.

Rosiñol:Janssen: Honoraria; Celgene: Honoraria. Cibeira:Janssen: Honoraria; Celgene: Honoraria. Mateos:Janssen: Honoraria; Celgene: Honoraria. Martinez:Janssen: Honoraria; Celgene: Honoraria. de la Rubia:Janssen: Honoraria; Celgene: Honoraria. Díaz-Mediavilla:Janssen: Honoraria; Celgene: Honoraria. Alegre:Janssen: Honoraria; Celgene: Honoraria. Lahuerta:Janssen: Honoraria; Celgene: Honoraria. San Miguel:Millennium Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Blade:Janssen: Honoraria; Celgene: Honoraria.