NGS Evaluation of the Eqol-MDS Trial: Preliminary Analysis of Eltrombopag for Thrombocytopenia of Low-Risk MDS

Background: In myelodysplastic syndromes (MDS), thrombocytopenia is an adverse risk factor. Treatments in this setting are scarce. In a randomized international phase 2 trial (EQoL-MDS, EudraCT number 2010-022890-33), we reported effecacy and safety of eltrombopag for the treatment of thrombocytopenia in the first 90 patients with lower-risk MDS with a platelet (PLT) count < 30 Gi/L (Oliva et al. Lancet Hem 2017). However, there are concerns of regulatory agencies regarding the use of thrombopoetin rececptor agonists in MDS due to previous reports signalling disease progression in clinical trials with the use of romiplostim and of eltrombopag, the latter in high risk MDS. Objective: We are further evaluating safety by conducting a comprehensive analysis of mutations in a panel of major driver or candidate driver genes in cases enrolled in the EQoL-MDS trial using targeted-capture sequencing.

Methods: Serial (every 3 months) sequencing was performed using the SureSelect custom kit (Agilent Technologies), for which 350 genes were selected from known oncogenes or tumour suppressor genes in haematological malignancies. Relevant somatic mutation data with (i) VAF > 0.05; (ii) depth > 100; (iii) P value for EBCall < 0.0001, were filtered by exclusion based on (i) synonymous SNVs; (ii) variants present only in unidirectional reads; (iii) variants occurring in repetitive genomic regions; (iv) missense SNVs with VAF of 0.4-0.6 or <0.04; and (v) known variants listed in SNP databases. The present analysis has been conducted at baseline, at 12 and 24 weeks.

Results: We present preliminary results of the first 21 cases (13 eltrombopag, 9 placebo) enrolled in the trial and with biological samples. Mean age was 62 (± 15) and 13 patients were male. According to the WHO 2016 classification, 11 patients had MDS with single lineage dysplasia (SLD), 7 had multi lineage dysplasia (MLD), 1 placebo case had excess blasts-1, and 1 placebo case had unclassifiable. IPSS-R risk was very low, low and intermediate in 4, 8 and 1 eltrombopag cases, respectively, and 5, 2 and 1 placebo cases, respectively. Karyotype was normal in 16 cases, del(20q) was detected in 4 cases and +14 in 1 case.

At study entry, in total 49 genes were mutated (Figure), where one or more of the 49 driver genes were mutated in all but 1 placebo patient (Table). The table shows characteristics and events of patients according to treatment arm. Noteworthy, in the eltrombopag arm, two cases experienced a loss of gene mutations, one obtaining International Working Group defined complete remission of MDS, while 1 MDS EB-1 case had a gain in ZRSR2. Two placebo cases experienced a gain in mutations

Conclusions: Treatment with eltrombopag in lower risk MDS is effective and safe. Preliminary analyses do not suggest that eltombopag induces disease progression neither at a clinical, nor a molecular level. Loss of mutations may occur during eltrombopag treatment with complete remission.

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