Thalidomide-Interferon Vs. Interferon Maintenance Therapy After Thal-Dex Vs. MP Induction Therapy in Elderly Patients with Multiple Myeloma.

Abstract

Abstract 2891Poster Board II-867Thalidomide maintenance therapy after completion of induction therapy plus ASCT and also after conventional therapy yielded conflicting results with some trials showing improvement in overall survival and others not.This study evaluates the efficacy of Thalidomide plus Interferon a2b (Thal-IFN) in comparison to interferon a2b (IFN) as maintenance therapy in elderly pts with multiple myeloma. For induction therapy, 289 pts had been randomized to either Thalidomide-Dexamethasone or to Melphalan-Prednisolone; results of this part of the study had been reported previously (BLOOD, 113, 3435-3442, 2009). 137 pts who had completed 9 cycles of induction therapy and had achieved stable disease or better were eligible for maintenance treatment, and 128 (median age 72 years, range 54 - 86 years) had finally been randomized to either Thal (starting dose: 200mg/day) in combination with IFN-a2b (Schering-Plough, 3 Mega U, TIW) or IFN a2b (IFN) at the same dose/schedule only. All pts were scheduled for zoledronate 4mg, q 4 weeks. Median follow up from randomization to maintenance: 35 mos. Median duration of maintenance therapy: 13.2 mos and 8.3 mos for pts randomized to Thal-IFN or to IFN, respectively (logrank test p=0.20).Maintenance therapy with Thal-IFN resulted in an improvement in the depth of response from PR to VGPR or CR in 5 (8%) and with IFN in 2 (3%) pts, respectively. Progression-free survival (PFS) was significantly longer in the Thal-IFN (27.7 mos) compared to the IFN only maintenance group (13.2 mos), (HR, 0.55; 95% 95% CI, 0.36-0.86; log-rank test, p=0.0068). Analysis of PFS by either Thal-Dex or MP induction therapy showed a significantly shorter PFS in pts started on Thal-Dex and subsequently randomized to IFN maintenance only (7.8 mos, log-rank test, p=0.037). PFS was 27.7 mos in pts started on Thal-Dex followed by Thal-IFN, 20.2 mos in those with MP induction therapy followed by IFN, and 27.6 mos in pts with Thal-IFN maintenance after MP induction therapy.Overall survival (OS) was similar in both groups (Thal-IFN 52.6 mos and IFN 51.4 mos, HR: 0.93, 95% CI: 0.53-1.66, log-rank test; p=0.81). OS by induction therapy did not vary significantly between the four treatment groups (logrank test, p=0.99). No significant difference in OS was seen between pts younger than 75 years and those aged 75 years or older (logrank test, p=0.39).Survival after progression of disease tended to be longer in pts who received IFN maintenance therapy only compared to those started on Thal-IFN (HR: 1.75, 95% CI, 0.97 – 3.14, logrank test: 0.056), while OS was similar between both groups when analyzed from termination of maintenance therapy (HR: 1.20, 95% CI, 0.65 – 2.20, log rang test 0.57).Baseline scores of the EORTC QLQ C30 items general health (Thal-IFN, mean 56; IFN, mean 59) and overall quality of life (Thal-IFN, mean 58; IFN, mean 60) were markedly below the score obtained in an healthy population (mean 75.3 and 73.3 respectively), but did neither differ at baseline between both groups nor did they vary significantly during the course of the maintenance (statistics will be provided). Cytogenetic data were available in 66 pts. PFS tended to be longer in pts with adverse FISH findings [t (4; 14), t (14; 20) Del 17p and abnormalities of 1q21] compared to the standard risk group, but differences were not significant (median: 31.5 vs. 21.6 mos, HR: 1.69, 95% CI, 0.13 – 3.07, log-rank test 0.084). The median of OS was 72.3 mos in those with standard risk and 39.6 mos in those with high risk features (HR: 1.94, 95% CI 0.91-4.13, log rank test: 0.082).In multivariate analysis (Cox model) only Thal-IFN maintenance therapy was shown to correlate significantly with PFS (HR: 0.61, 95% CI: 0.39-0.89, p=0.04) while for poor performance status, low hemoglobin, and low albumin a statistically non-significant correlation with survival was noted.Hematologic toxicity was similar between both groups. Pts on Thal-IFN maintenance experienced significantly more neuropathy (p=0.0024), constipation (p=0.0007) and skin toxicity (p=0.0063) and increase in renal impairment (p=0.037). In addition, there was a tendency for more dyspnea (p=0.40) and more fatigue (p=0.11) in pts on Thal-IFN maintenance therapy. Other non-hematological toxicities were similarly distributed in both therapy arms.In conclusion, Thal-IFN maintenance therapy resulted in increased PFS compared IFN maintenance treatment only, but OS was similar between both groups. Disclosures:Ludwig:Celgene: Honoraria; Mundipharma: Honoraria; AMGEN: Honoraria; Ortho-Biotech : Honoraria; Janssen-Cilag: Research Funding; Roche: Honoraria. Hajek:Janssen-Cilag: Honoraria. Kuhn:Schering-Plough: Employment.