Lenalidomide in Relapsed and Refractory Multiple Myeloma Disease: Feasibility and Benefits of Long-Term Treatment

Abstract 4069

Despite the progress obtained by the introduction of novel agents, treatment of relapsed/refractory multiple myeloma (rrMM) remains a clinical challenge. Long-term treatment aims to delay progression of MM, but there is concern regarding tolerance, especially in the non-study patient (pt) population. The mode of action of Lenalidomide (len) as an immunomodulatory agent and the tolerability profile led to approval of the drug for continuous treatment until disease progression (PD) or unacceptable toxicity. Due to the lack/scarcity of reports assessing benefit and risk of long-term len treatment in non-selected rrMM patients, we retrospectively analysed the long-term outcome in pts with rrMM treated with len/dex.

67 pts who were treated with len/dex for rrMM in the approved indication until PD or unacceptable toxicity from 2007 to 2011 were included in this retrospective, single-centre analysis. Median age was 68 years (y) (range 40–84y), median number of pretreatments were 2 (range 1–6). 31 pts (46%) had relapsed after autologous stem cell transplant, 10 pts (15%) after allogeneic transplantation. 40 pts (60%) received prior treatment with bortezomib, 13 (19%) with thalidomide-containing regimen. Cytogenetic analysis was available in 28 pts (41.8%), 8 pts had cytogenetic high-risk disease defined as presence of t(4;14), del17 or +1q21 in FISH analysis. Overall response rate (ORR) under len/dex was 82.1% comprising 41 pts (61.2%) with PR, 9 pts (13.4%) with VGPR and 5 pts (7.5%) with CR. Median time to best response was 5.5 months (mo)., median time to documented CR 36.6 mo. Median treatment duration with len was 16.1 mo (range 0.7–47.4 mo). 45 pts (67.2%) were treated with len/dex >12 mo, 25 (37.3%) >24 mo, 9 (13.4%) >36 mo and 14 pts were still on treatment at the time of analysis. Of the 45 pts with len treatment >12 mo 21 pts underwent prior autologous transplant, and 7 pts allogeneic transplantation. 4/8 pts with high-risk cytogenetics were treated with len >12 mo. Among the 22 pts with len <12 mo, 12 pt discontinued treatment due to PD, in 8 pts treatment was stopped due to toxicity or patient's wish; 2 pts proceeded to allogenic transplantation. Reasons for treatment discontinuation other than PD were fatigue, subjective intolerance and, in one pt, a thrombembolic event. In pts >12 mo on len, documented main toxicities were hematologic with grade III/IV toxicity in 17 pts (37.8%). Median overall survival (OS) of the total pt population was 33.2 mo, whereas OS of pts discontinuing len before 12 mo was 14.4 mo (20.5 mo for pts stopping for other reasons than PD; p=0.0003), pts treated beyond 12 mo had a median OS of 42.9 mo (p<0.0001). OS of pt >12 mo on len treatment did not significantly differ between pts that had received autologous transplantation, allogeneic transplantation or conventional therapy (43.1 mo, 48.0 mo, 36.8 mo, respectively).

To the best of our knowledge, this is the first report on feasibility and efficacy of long-term len treatment in a non-selected pt cohort with rrMM. We thereby provide evidence that len is an efficient and safe long-term treatment option providing clinical benefit for the majority of patients. Outcome of pt >12 mo on len is superior when compared to pt discontinued earlier for reasons other than PD. Furthermore, the favourable outcome of pts treated for more than 12 mo was independent of previous autologous and allogeneic transplantation. Our data confirm the current use of len as a continuous long-term treatment strategy.