Addition of Lenalidomide (LEN) to Azacitidine (AZA) (Combined vs Sequential Treatment) in High-Risk Myelodysplastic Syndromes (MDS): A Randomized Phase II Multicenter Study

Introduction. Azacitidine (AZA) as single agent has been shown to improve overall survival in high-risk myelodysplastic syndromes (MDS), with an overall response rate (ORR) of 50-60% (Silverman 2002; 2006; Fenaux 2009). However as a significant proportion of patients (pts) do not respond to treatment, and moreover, as the the duration of therapeutic response to AZA is limited, several attempts have been made to associate AZA with other drugs, with the aim to improve the outcome. In particular, the addition of lenalidomide (LEN) to AZA, either administered concurrently (Sekeres, 2010; 2012), or sequentially (Platzbecker, 2013), has shown promising results, although these data await confirmation by larger series of pts. The aim of this study was to evaluate the efficacy (ORR) and safety of the combination vs the sequential use of AZA and LEN in high-risk MDS pts. Moreover, as in previous studies we demonstrated that the increase in PI-PLCβ1 gene expression during AZA treatment is related to haematological response and frequently anticipates the response (Follo, 2009; 2012), another aim of our study was to assess the evaluation of PI-PLCβ1 expression as early predictive biomarker of response also with the association of AZA and LEN, and to look for other possible biomarkers able to predict response, as the mutational status assessed by next generation sequency (NGS).

Methods. This is a randomized, phase II, multicenter, open label study, including pts with MDS (according to WHO 2008 classification) with International Prognostic Scoring System (IPSS) risk High or Intermediate-2, without previous treatment with AZA or LEN. ARM 1 (combined treatment): AZA: 75 mg/m²/day (days 1-5) I.C. + LEN: 10 mg/day (days 1-21), orally, every 4 weeks. ARM 2 (sequential treatment): AZA: 75 mg/m²/day (days 1-5) I.C. + LEN: 10 mg/day (days 6-21), orally, every 4 weeks. The treatment for both arms was planned for 8 cycles (32 weeks) in the absence of disease progression or unacceptable toxicity. A sample size of 44 pts was planned.

Results. From March 2013, 40 pts (23 males), with a median age of 72 (48-83 yrs) were enrolled, from 13 hematologic italian Centers. At baseline, WHO diagnosis was: Refractory Cytopenia with Multilineage Dysplasia (RCMD): 3 pts; Refractory Anemia with Excess of Blasts-1 (RAEB-1): 9 pts; RAEB-2: 23 pts; MDS-unclassified (MDS-U): 5 pts; IPSS risk was: Intermediate-2: 29 pts; High: 6 pts; not determined (N.D.) (because of lack of cytogenetic data): 5 pts. (all with RAEB-2). IPSS cytogenetic risk was: intermediate in 10 pts and high in 9 pts (3 with complex karyotypes and 6 with isolated -7 or 7q-). 5 pts showed del5q (in 3 cases in the context of a complex karyotype, and in 1 case associated with another single additional cytogenetic alteration). 2 pts had therapy-related MDS. 21 pts (52.5%) were transfusion-dependent at baseline. 19 pts were randomly assigned to ARM 1, and 21 pts to ARM 2. At the time of this analysis, 22/40 pts (55%) completed ≥ 6 cycles of treatment, and are evaluable for response. 13/22 pts (59,1%) showed a favourable response to treatment, following the International Working Group (IWG) criteria (Cheson, 2006): 2 pts achieved Complete Remission (CR), 2 pts attained Partial Remission (PR), 2 pts showed Marrow Complete Remission (mCR), and 7 pts obtained Hematological Improvement (HI), while the 9 non responder pts maintained a Stable Disease (SD). Responder pts were 7/10 (70%) in ARM 1 (2 CR; 1 PR; 4 HI), and 6/12 (50%) in ARM 2 (1 CR; 1 PR; 2 mCR; 2 HI), respectively. Median time to first response: 2 (2-7) months. A significant toxicity (grade > 2) was observed in 10/40 (25%) pts. 15/40 pts (37,5%) had a dose reduction of LEN because of hematologic or non-hematologic toxicity. 8 pts (20%) early discontinued therapy before completing the planned 8 cycles, because of prolonged thrombocytopenia (1 pt), death (3 pts), evolution into acute myeloid leukemia (AML) (2 pts) and withdrawal of consent (2 pts), respectively. Causes of death were: febrile neutropenia, myocardial infarction and sudden death, respectively .

Conclusions. Our results, although preliminary, seem to confirm the feasibility of the association of AZA and LEN in high-risk MDS pts. More data are needed in order to compare the efficacy and safety of combined vs sequential treatment and vs AZA monotherapy. Moreover, possible relationships with signal transduction pathways and with mutational status are under evaluation.