Correction to: International Journal of Hematology (2019) 109:409–417 https://doi.org/10.1007/s12185-019-02607-z

The authors would like to correct the errors in the publication of the original article. The correction details are given below:

The fifth sentence under the heading “Abstract” should read as “Median PFS was 4.4 months, 12.1 months, and 35.5 months in Groups A, B, and C, respectively, and was significantly prolonged in Group C than in Group A (p = 0.016).”.

The paragraphs under the heading “Efficacy” in “Results” section should read as below:

The median duration of the maintenance therapy with thalidomide was 13.2 months in whole cases, 13.2 months in Group B, and 14.2 months in Group C, respectively. The response to induction therapy was; complete response in 6 patients (17.6%), very good partial response in 12 patients (35.3%), partial response in 11 patients (32.3%), and stable disease in 5 patients (14.7%), respectively. There was no significant difference in the overall response rate (≥ PR) among Groups A (75.0%), B (91.7%), and C (90.0%). In the thalidomide maintenance groups (22 patients), there was an improvement in the depth of response during the maintenance therapy in 3 patients (13.6%; 2 in Group B and 1 in Group C), and a sustainment of response after induction therapy in 8 patients (36.4%). Progression of the disease occurred in 10 patients in Group A (83.3%), 8 patients in Group B (66.7%), and 4 patients in Group C (40%), respectively, during the maintenance phase, however, there was no significant difference between the 3 groups. The 2-year PFS rate was 25.0%, 33.3%, and 68.4% in Groups A, B, and C, respectively. Median PFS was 4.4 months, 12.1 months, and 35.5 months in Groups A, B, and C, respectively (Fig. 1a), and was significantly prolonged in Group C than in Group A (p = 0.016). There was no significant difference in median OS from the initiation of maintenance therapy between Groups A, B, and C (38.3 months, not reached, and 37.0 months, respectively) (Fig. 1b).

There was no significant difference in median PFS between the patients who received induction therapy with conventional chemotherapy-based regimen (11.2 months) and those who received novel agents-based regimen (12.4 months) (p = 0.859) (Fig. 2a). There was no significant difference in median PFS between newly-diagnosed patients (12.1 months) and relapsed patients (25.2 months) (p = 0.246) (Fig. 2b).

The second sentence under the heading “Discussion”, “The 2-year PFS rate from the initiation of maintenance therapy was significantly higher in Group C (100 mg cohort) than in Group A (no maintenance cohort) (p = 0.005).” should be deleted and the third sentence should read as “The median PFS was significantly prolonged in Group C (100 mg cohort) than in Group A (no maintenance cohort) (p = 0.016) (Fig. 1a), but there was no difference between the Groups B and A.”

In addition, revised Figs. 1 and 2 were given in this correction.

Fig. 1
figure 1

Kaplan–Meier estimates for progression-free survival and overall survival according to study groups. a Progression-free survival curves for the non-maintenance group (median: 4.4 months), the 50 mg thalidomide maintenance group (median: 12.1 months), and the 100 mg thalidomide maintenance group (median: 35.5 months). b Overall survival curves for the non-maintenance group (median: 38.3 months), the 50 mg thalidomide maintenance group (median: not reached), and the 100 mg thalidomide maintenance group (median: 37.0 months)

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Fig. 2
figure 2

Kaplan–Meier estimates for progression-free survival according to induction therapy regimen and patient status. a Progression-free survival curves for patients treated with conventional chemotherapy-based regimen (median: 11.2 months) and those treated with novel agent-based regimen (median: 12.4 months). b Progression-free survival curves for newly diagnosed patients (median: 12.1 months) and relapsed patients (median: 25.2 months)

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