The Therapeutic Effect of Lenalidomide Is Enhanced After Allogeneic Stem Cell Transplantation: Results of a Case-Control Study

Lenalidomide (Len) is a highly effective drug against multiple myeloma (MM). It acts through several mechanisms, such as a direct cytotoxic effect, anti-angiogenesis, microenvironment modifications, and immunomodulation. The latter property is particularly interesting in the allogeneic hematopoietic stem cell transplantation (Allo-HSCT) setting, since Len may interact favourably with the graft-versus-myeloma (GVM) effect. Preliminary results from retrospective studies on heterogeneous patient populations have suggested that Len is more effective when given after Allo-HSCT. In order to verify this observation, we have conducted a case-matched analysis comparing Len after autologous stem cell transplantation (Auto-HSCT) vs. Len after Allo-HSCT. The hypothesis is that Len may be more potent when administered after Allo-HSCT.

In this retrospective study the matching criteria was represented by the number of treatment lines received before Len. In an attempt to uniform the treatment regimens, an intra-centre matching was recommended. To April 2011 we collected data from 39 patients in each group. Baseline characteristics between Auto and Allo patients were similar, except for age at diagnosis (53 years, range 39–70, in Auto patients; 47 years, range 29 – 61, in Allo patients). The median number of previous lines of treatment was 3 (range 1–6 ) for both groups. Twenty-one out 39 (54%) Allo patients received Allo-HSCT as second or subsequent line of therapy. Thirty-two (82%) Auto and 35 (90%) Allo patients received bortezomib in previous lines. Similarly, 34 (87%) Auto and 12 (54%) Allo patients were previously treated with thalidomide. Len was always combined with dexamethasone. Median time between Auto-HSCT and Len start was 38 months (range 7–159), and for Allo-HSCT 29 months (range 4–215). Best responses were for Auto and Allo patients as follows: 5 vs. 4 CR, 6 vs. 8 VGPR, 11 vs. 12 PR, 6 vs. 8 SD, 11 vs. 7 PD. Time from Len start to the best response was 4 months for both groups. With a median follow-up of 11.5 months (range 1–39), 1 year and 2 year progression-free survival were 41% and 6% for Auto patients, and 52% and 44% for Allo patients (p=0.03), respectively. Two years overall survival was 48% for Auto and 75% for Allo patients (p=0.03). Similar results were observed regardless of previous thalidomide treatment. No unexpected toxicities were reported. Two (10%) patients had worsening of a pre-existent extensive chronic GVHD.

The comparison between Auto and Allo patients has shown a benefit in terms of PFS and OS in favor of Len administered after AlloHSCT. This observation supports the hypothesis that Len is synergistic with the GVM effect. Since Len has a potent immunomodulatory effect, this can raise concerns about its use after AlloHSCT. A Dutch prospective study showed that the early administration of Len 10 mg daily after non-myeloablative Allo-HSCT induces late onset acute GVHD in a substantial proportion of patients, causing the premature discontinuation of the study. On the contrary, our retrospective study has shown that a later administration is feasible and safe, without an excess of GVHD, suggesting that a more mature immune system can better tolerate Len. Moreover, since in all cases dexamethasone was given in combination with Len, its immunosuppressive effect may have harnessed the Len-induced immune activation. In conclusion our study suggests that Len is particularly active after AlloHSCT, still retaining a favorable toxicity profile.

No relevant conflicts of interest to declare.