Multivariate time-dependent comparison of the impact of lenalidomide in lower-risk myelodysplastic syndromes with chromosome 5q deletion

Authors


  • J.S.-G. and G.S. contributed equally to this work.
  • Presented partly at the Plenary Session of the 11th International Symposium on Myelodysplastic Syndromes, Edinburgh, United Kingdom, May 18–21, 2011.

Summary

The impact of lenalidomide treatment on long-term outcomes of patients with lower risk myelodysplastic syndromes (MDS) and chromosome 5q deletion (del(5q)) is unclear. This study used time-dependent multivariate methodology to analyse the influence of lenalidomide therapy on overall survival (OS) and acute myeloblastic leukaemia (AML) progression in 215 patients with International Prognostic Scoring System (IPSS) low or intermediate-1 risk and del(5q). There were significant differences in several relevant characteristics at presentation between patients receiving (n = 86) or not receiving lenalidomide (n = 129). The 5-year time-dependent probabilities of OS and progression to AML were 62% and 31% for patients receiving lenalidomide and 42% and 25% for patients not receiving lenalidomide; differences were not statistically significant in multivariate analysis that included all variables independently associated with those outcomes (OS,= 0·45; risk of AML,= 0·31, respectively). Achievement of RBC transfusion independency (= 0·069) or cytogenetic response (= 0·021) after lenalidomide was associated with longer OS in multivariate analysis. These data clearly show that response to lenalidomide results in a substantial clinical benefit in lower risk MDS patients with del(5q). Lenalidomide treatment does not appear to increase AML risk in this population of patients.

Deletion of the long arm of chromosome 5 (del(5q)) is the most common chromosomal abnormality in myelodysplastic syndromes (MDS) and MDS associated with isolated del(5q) is recognized as an independent entity in the World Health Organization (WHO) classification portraying a relatively good-prognosis (Vardiman et al, 2009; Schanz et al, 2012).

Lenalidomide induces high rates of red blood cell (RBC) transfusion independence and cytogenetic response in lower risk MDS patients (International Prognosis Scoring System [IPSS] low or Intermediate-1) (Greenberg et al, 1997) with del(5q) and RBC transfusion dependence (List et al, 2005, 2006; Fenaux et al, 2011) but data on its effect on overall survival (OS) and progression to AML are very limited. Long-term outcomes were not addressed in the earlier single-arm clinical trials of lenalidomide in this subset of patients (List et al, 2005, 2006) and the cross-over design of the randomized placebo-controlled clinical trial of lenalidomide in this setting (Fenaux et al, 2011) precluded to meaningfully analyse the long-term effect of lenalidomide. Thus, lack of data and reports of a possible increase in the risk of progression to AML are of concern (Göhring et al, 2010). As there is no randomized clinical trial in progress or in project to determine the potential long-term influence of lenalidomide in this population, the only way to address this issue is by means of large retrospective comparative studies that use the most adequate methodology. These studies lack the quality of prospective randomized clinical trials and have important limitations but may offer relevant information when no better sources are available.

The major aim of this study was to analyse the impact of lenalidomide treatment on OS and risk of progression to AML in a large series of 215 patients with lower risk MDS and del(5q) with prolonged follow-up. Multivariate time-dependent statistical analyses were used to avoid the potential confounding effect of other covariates (Kantarjian et al, 2009; Mallo et al, 2011; Germing et al, 2012) and the bias due to the different time period elapsed since diagnosis to starting lenalidomide.

Patients and methods

Data collection

At the completion of this report the database of the Spanish MDS cooperative group (GESMD) contained complete information on 4980 patients with MDS, diagnosed according to French-American-British (FAB) criteria (Bennett et al, 1982). Deletion 5q alone or accompanying other chromosomal abnormalities was present in 512 patients. All data were double-checked for data inconsistency. Specific data on response to lenalidomide treatment were additionally recorded for patients treated with lenalidomide.

Inclusion and diagnostic criteria

The primary objective of the study was to assess the potential effect of lenalidomide on OS and risk of progression to AML in patients with lower risk primary MDS with del(5q). Thus, for their inclusion in this study patients had to fulfill all the following criteria: (i) an unambiguous diagnosis of MDS according to FAB criteria (Bennett et al, 1982), (ii) no previous treatment with chemotherapy or radiotherapy, (iii) successful conventional cytogenetic study at diagnosis with presence of del(5q) alone or with additional abnormalities, (iv) IPSS score ≤1 point (low-risk or intermediate-1 IPSS risk categories) (Greenberg et al, 1997) at diagnosis and also at the start of lenalidomide for patients receiving lenalidomide, and (v) appropriate follow-up data. Two hundred and fifteen patients were included in the analysis, of whom 86 had received lenalidomide; 129 had not received lenalidomide. Most patients who were not treated with lenalidomide received only supportive care (RBC and platelet transfusions and antibiotics as required). Ten patients received AML-type chemotherapy (n = 6, one of them treated with lenalidomide) or allogeneic haematopoietic stem cell transplantation (n = 4, one treated with lenalidomide). Fifteen patients (14 of them treated with lenalidomide) received azacitidine after disease progression. The presence of del(5q) had been detected by conventional cytogenetics performed on bone marrow samples obtained at the time of diagnosis and processed following standard chromosome-banding procedures. The cytogenetic reports of all cases were centrally reviewed to ensure they followed the International System of Human Cytogenetic Nomenclature 2009 guidelines (Shaffer et al, 2009). In keeping with the guidelines of the Declaration of Helsinki, the study was conducted with the approval of the internal review boards of Hospital Universitario Reina Sofía and GESMD. All patients provided informed consent.

Treatment with lenalidomide and evaluation of response

Sixty-nine patients treated with lenalidomide obtained the drug on a case-by-case basis as part of the compassionate use programme for lenalidomide in Spain, starting in January 2006. The remaining 17 patients were included in the MDS-004 clinical trial (Fenaux et al, 2011). In patients not participating in MDS-004 clinical trial all decisions on performance of bone marrow aspirates for morphological and cytogenetic evaluation during follow-up were taken individually and at the discretion of the attending physician.

RBC transfusion dependence was defined as having at least one RBC transfusion every 8 weeks over a period of 4 months. Achievement of RBC transfusion independence in RBC transfusion-dependent patients was defined as the absence of RBC transfusions lasting for at least 8 weeks. Cytogenetic response to lenalidomide was assessed using consensus criteria (Cheson et al, 2006).

Prognostic factors

Different patient and disease characteristics recorded at diagnosis and the use of lenalidomide were examined to establish their possible relationship with outcomes. The demographic, clinical, and biological characteristics included were age, gender, haemoglobin level, absolute leucocyte, polymorphonuclear (PMN) and platelet counts, percentage of blasts in peripheral blood and bone marrow, percentage of dysplastic cells in the different haematopoietic cell lines, serum levels of lactate dehydrogenase, ferritin and erythropoietin, IPSS cytogenetic risk categories (Greenberg et al, 1997), FAB (Bennett et al, 1982) and WHO morphological subtypes (Swerdlow et al, 2008), and IPSS (Greenberg et al, 1997) and WHO-based prognostic scoring system (Malcovati et al, 2007).

Statistical analysis

Comparisons of proportions and ranks were performed by Fisher's exact test and Mann-Whitney U test as appropriate. OS was measured from diagnosis to last follow up or death from any cause. Evolution to AML was measured from diagnosis to the date of AML (presence of more than 19% of blasts in bone marrow or peripheral blood). Patients dying before leukaemic evolution were considered as censored at the time of death. Patients undergoing haematopoietic allogeneic stem cell transplantation or AML-type chemotherapy were censored at the date of transplant or chemotherapy. Patient follow-up was updated on 30 September, 2010, and all follow-up data were censored at that point. Unadjusted time-to-event actuarial curves for covariates available at presentation were plotted using the Kaplan-Meier estimate (Kaplan & Meier, 1958). The Simon-Makuch method was used for depicting time-to-event actuarial curves of the time-dependent covariate (treatment with lenalidomide) (Simon & Makuch, 1984; Schultz et al, 2002). This method allows coping with delayed entry of patients into the actuarial curves. Briefly, in the Simon-Makuch actuarial method all patients enter at diagnosis into the curve of patients not receiving lenalidomide. Patients not receiving lenalidomide remain in that curve until death (for estimating OS), development to AML (for estimating risk of AML progression) or last follow-up (for both outcomes) whereas patients receiving treatment with lenalidomide, the time-dependent covariate, remain in the initial curve only until they start treatment with lenalidomide. At that time point (i) they are considered as censored data in the curve of untreated patients and (ii) cross over to the curve of patients receiving treatment with lenalidomide (delayed entry) and remain in that curve until death, AML development, or last follow-up. Log rank tests were used for comparisons between actuarial curves of time-independent covariates (Mantel, 1966). Univariate comparison of actuarial curves for time-dependent covariate (lenalidomide treatment) was analysed by likelihood ratio test obtained in the first step of a forward selection procedure of Cox's proportional hazards regression model (Cox, 1972). Multivariate analysis was performed using Cox's proportional hazards regression model, with lenalidomide therapy being evaluated as a time-dependent covariate (Fisher & Lin, 1999). Characteristics selected for possible inclusion in the multivariate model were those for which there was some indication of association with OS or AML progression in univariate analysis (< 0·20) or for which previous studies have reported an independent prognostic value (Kantarjian et al, 2009; Mallo et al, 2011; Germing et al, 2012). Further, the variable lenalidomide treatment was always selected for potential inclusion in the multivariate models to be completely sure that a significant effect of lenalidomide therapy on the major outcome endpoints was not blurred by its association with a confounding covariate. The forward stepwise procedure was stopped when the P value for entering an additional variable was >0·05. Two-sided P values <0·05 were considered as statistically significant. In line with the essentially exploratory nature of the study, no adjustment for multiple testing was applied. All statistical analyses were performed using the open source software R version 2.13.1 (http://www.r-project.org/).

Results

Characteristics of the patients

The main characteristics at diagnosis of the overall series of 215 patients as well as those of patients receiving (n = 86) or not (n = 129) lenalidomide therapy are summarized in Table 1. The median age of the 215 patients was 72 years and 71% were females. By WHO 2008 criteria 107 (50%) patients had MDS associated with isolated del(5q) and 44 (20%) had refractory anaemia with excess of blasts (RAEB) type 1 subtypes and according to the IPSS, 93 (43%) and 122 (57%) patients respectively had low-risk and intermediate-1 risk. As expected, patients treated with lenalidomide were diagnosed in more recent years (median, August 2006; range, February 1995–Jan 2010) than control patients (median, April 2001; range, November 1972–February 2010; < 0·001). Similarly, patients receiving lenalidomide were younger (= 0·01), showed lower haemoglobin levels (= 0·025), had lower absolute PMN counts (= 0·049) and higher platelet counts (= 0·004), higher ferritin levels (= 0·039), higher proportion of dysmegakaryopoiesis (= 0·003) and were more frequently RBC transfusion-dependent (= 0·001). Both groups of patients were similar regarding other relevant characteristics.

Table 1. Main demographic, clinical and biological characteristics at diagnosis in the overall series of 215 lower risk MDS patients with del(5q) and according to lenalidomide treatment.
CharacteristicOverall Series (n = 215)Patients not treated with lenalidomide (n = 129)Patients treated with lenalidomide (n = 86)P value
  1. P values denotes differences between patients receiving or not lenalidomide for the corresponding characteristic; WBC, white blood cell; WHO, World Health Organization; RCUD – RA, refractory cytopenia with unilineage dysplasia – refractory anaemia; RARS, RA with ring sideroblasts; RCMD, refractory cytopenia with multilineage dysplasia; RAEB-1, RA with excess blasts type 1; MDS, myelodysplastic syndromes; MDS/MPN, myelodysplastic/myeloproliferative neoplasms; LDH, lactate dehydrogenase; EPO, erythropoietin; RBC, red blood cell; IPSS, International Prognostic Scoring system; WPSS, WHO-based Prognostic Scoring system.

  2. a

    Mann–Whitney U-test.

  3. b

    Fisher's exact test.

  4. c

    Percentage of dyserythropoiesis was available in 77 patients (43 receiving lenalidomide and 34 not receiving lenalidomide).

  5. d

    Percentage of dysgranulopoiesis was available in 67 patients (42 receiving lenalidomide and 25 not receiving lenalidomide).

  6. e

    Percentage of dysthrombopoiesis was available in 77 patients (43 receiving lenalidomide and 34 not receiving lenalidomide).

  7. f

    LDH serum level was available in 142 patients (67 receiving lenalidomide and 75 not receiving lenalidomide).

  8. g

    Ferritin serum level was available in 125 patients (65 receiving lenalidomide and 60 not receiving lenalidomide).

  9. h

    EPO serum level was available in 69 patients (40 receiving lenalidomide and 29 not receiving lenalidomide).

  10. i

    RBC transfusion dependency was defined as having at least one RBC transfusion every 8 weeks over a period of 4 months.

  11. j

    RBC transfusion dependence at diagnosis was available in 158 patients (73 receiving lenalidomide and 85 not receiving lenalidomide).

  12. k

    WPSS risk category at diagnosis was available in 104 patients (33 receiving lenalidomide and 71 not receiving lenalidomide).

Age, median (range), years72 (35–90)73 (37–90)70 (35–90)0·012a
<60 years, n (%)41 (19)18 (14)23 (27)0·019b
≥60 years, n (%)174 (81)111 (86)63 (73)
Female gender, n (%)153 (71)89 (69)64 (74)0·389b
Haemoglobin, median (range), g/l95 (30–160)98 (30–140)94 (30–160)0·055a
<100 g/l, n (%)133 (62)72 (56)61 (71)0·025b
≥100 g/l, n (%)82 (38)57 (44)25 (29)
WBC count, median(range), ×109/l4·4 (1·6–124)4·5 (1·6–124)4·2 (1·7–20·1)0·21a
<4 × 109/l, n (%)81 (38)42 (33)39 (45)0·058b
≥4 × 109/l, n (%)134 (62)87 (67)47 (55)
Neutrophil count, median(range), ×109/l2·2 (0·02–53·3)2·3 (0·08–53·3)1·9 (0·02–17·9)0·146a
<1·8 × 109/l, n (%)78 (36)40 (31)38 (44)0·049b
≥1·8 × 109/l, n (%)137 (64)89 (69)48 (56)
Platelet count, median (range), ×109/l247 (15–1161)244 (15–1000)255 (53–1161)0·174a
<150 × 109/l, n (%)49 (23)38 (29)11 (13)0·004b
≥150 × 109/l, n (%)166 (77)91 (71)75 (87)
Percentage of bone marrow blasts, n (%)
0–4171 (80)102 (79)69 (80)0·836b
5–1044 (20)27 (21)17 (20)
Dyserythropoiesis,c median (range),%20 (0–100)10 (0–100)20 (0–75)0·467a
Dysgranulopoiesis,d median (range),%20 (0–100)11 (0–76)32 (0–100)0·059a
Dysthrombopoiesis,e median (range),%56 (0–100)33 (0–85)70 (0–100)0·003a
WHO classification subtype, n (%)
RCUD – RA3 (1)2 (2)1 (1)0·546b
RARS6 (3)5 (4)1 (1)
RCMD43 (20)27 (21)16 (19)
RAEB-144 (20)27 (21)17 (20)
MDS associated with isolated del(5q)107 (50)60 (47)47 (55)
MDS – unclassified5 (2)3 (2)2 (2)
MDS/MPN7 (3)5 (4)2 (2)
LDH serum level,f median (range), u/l333 (30–1737)308 (30–1737)359 (62–1113)0·150a
Ferritin serum level,g median (range), μg/l202 (21–4732)186 (21–4732)240 (29–3974)0·303a
< 500 μg/l, n (%)101 (81)53 (88)48 (74)0·039b
≥ 500 μg/l, n (%)24 (19)7 (12)17 (26)
EPO serum level,h median (range), u/l166 (2–1820)124 (13–1820)200 (2–1540)0·325a
Chromosomal abnormalities, n (%)
del(5q) alone169 (79)97 (75)72 (84)0·250b
del(5q) + 1 additional abnormality29 (13)19 (15)10 (12)
del(5q) + 2 or more additional abnormalities17 (8)13 (10)4 (5)
RBC transfusion dependency,i,j n (%)66 (42)26 (31)40 (55)0·001b
IPSS risk category, n (%)
Low93 (43)55 (43)38 (44)0·822b
Intermediate-1122 (57)74 (57)48 (56)
WPSS risk category,k n (%)
Very low30 (29)24 (34)6 (18)0·193b
Low46 (44)26 (37)20 (61)
Intermediate14 (14)10 (14)4 (12)
High12 (12)9 (13)3 (9)
Very high2 (2)2 (3)0 (0)

Survival and risk of progression to AML in the overall series according to treatment with lenalidomide

The median follow-up for patients alive in the overall series was 35 months (range, 4–177 months), and was 40 months (range, 6–177 months) and 32 months (range, 4–156 months) respectively in patients receiving or not lenalidomide. The median time interval from diagnosis to starting lenalidomide was 12 months (range, 0·3–149 months) and the median follow-up after starting lenalidomide was 22 months (range, 3–55 months).

At last follow-up, 101 of 215 patients (47%) had died; 19 of 86 patients treated with lenalidomide (22%) and 82 of 129 patients not receiving the drug (64%). By Kaplan-Meier methodology the actuarial median OS for the overall series was 59 months and the estimated probability ± standard deviation (SD) of OS at 2 and 5, years was 81% ± 3% and 48% ± 4%, respectively. The estimated time-dependent actuarial median OS was 62 months for patients receiving lenalidomide and 53 months for patients who did not received the drug, and the actuarial probabilities of OS at 2 and 5 years were 92% ± 6% and 62% ± 9% for patients treated with lenalidomide and 76% ± 3% and 42% ± 5% for patients who did not receive lenalidomide (hazard ratio [HR], 0·76, 95% confidence interval [CI], 0·46–1·27; = 0·29) (Fig 1A).

Figure 1.

Unadjusted time-dependent actuarial curves of OS and progression to AML in the overall series of 215 patients with lower-risk MDS with del(5q) according to lenalidomide treatment (lenalidomide, n = 86; no lenalidomide, n = 129). (A) Probability of OS. (B) Cumulative probability of progression to AML. Solid lines (──) indicate lenalidomide treatment (n = 86) and dashed lines (- - -) denote no lenalidomide treatment (n = 215). Patients treated with lenalidomide (n = 86) are included in both actuarial curves (see “'Statistical analysis'” for details). P values were assessed by likelihood ratio tests obtained in the first step of a forward selection procedure of Cox's proportional hazards regression model with lenalidomide treatment included as time-dependent covariate. OS, overall survival; SD, standard deviation; AML, acute myeloid leukaemia; MDS, myelodysplasic syndrome.

Forty of 215 patients (19%) had evolved to AML at the time of analysis; 11 of 86 patients (13%) who were treated with lenalidomide and 29 of 129 patients (23%) who were not treated with lenalidomide. For the overall series, the 2- and 5-year actuarial cumulative probability ± SD of progression to AML was 13% ± 3% and 32% ± 4%, respectively. Time-dependent estimated cumulative probabilities of evolution to AML at 2 and 5 years were respectively 6% ± 4% and 31% ± 10% for patients receiving lenalidomide, and 12% ± 3% and 25% ± 5% for those who did not receive lenalidomide (HR, 1·37, 95% CI, 0·67–2·79; = 0·39; Fig 1B).

The main results of the multivariate analysis of prognostic factors for OS and risk of progression to AML with lenalidomide as time-dependent covariate are shown in Table 2. Treatment with lenalidomide did not show any significant effect on OS (HR, 0·82, 95% CI, 0·49–1·37; = 0·45) or on risk of progression to AML (HR, 1·45, 95% CI, 0·71–2·98; = 0·31).

Table 2. Multivariate analysis of long-term outcomes with lenalidomide treatment as time-dependent covariate and forced to enter into the models.
Variable (categories and codes)Overall survivalRisk of progression to AML
Beta coefficient (SE)Hazard ratio (95% CI)P valueBeta coefficient (SE)Hazard ratio (95% CI)P value
  1. SE, standard error; NS, not statistically significant (P > 0·20).

Lenalidomide treatment (no = 0, yes = 1)−0·21 (0·26)0·82 (0·49–1·37)0·450·37 (0·37)1·45 (0·71–2·98)0·31
Platelet count, ×109/l (<150 × 109/l = 0, ≥150 × 109/l = 1)−0·85 (0·22)0·43 (0·28–0·66)<0·001−1·0 (0·37)0·37 (0·20–0·87)0·005
Age, years (<60 years = 0, ≥60 years = 1)0·54 (0·28)1·72 (0·99–2·97)0·051−0·69 (0·34)0·50 (0·26–0·98)0·043
Chromosomal abnormalities (del(5q) alone = 0, del(5q) + 1 additional abnormality = 1, and del(5q) + ≥2 additional abnormalities = 2)0·47 (0·25)1·59 (0·98–2·58)0·0580·87 (0·35)2·39 (1·14–4·99)0·020
Blasts in bone marrow,% (<5% = 0, ≥5% = 1)NS0·23 (0·08)1·26 (1·07–1·49)0·006

Effect of lenalidomide therapy in RBC transfusion-dependent patients

Sixty-five RBC transfusion-dependent patients at start of lenalidomide therapy were evaluable for achievement of RBC transfusion independence (TI) after lenalidomide. Fifty-one of them (78%) achieved RBC TI. In our series, median time to achieve RBC TI after lenalidomide start was 2·2 months (range, 1–11). The Kaplan-Meier median OS from start of lenalidomide treatment was not reached after a median follow-up of 26 months for the 51 patients achieving RBC TI (probability of OS at 2 years, 93% ± 4%) whereas it was 31 months for the 14 patients who did not obtain TI (log rank < 0·001). The corresponding actuarial cumulative probabilities of progression to AML at 2 years from starting lenalidomide were 3% ± 2% for patients attaining RBC TI and 23% ± 14% for those not achieving RBC TI (log rank < 0·001). The median duration of RBC TI was 36 months and was maintained at last follow-up in 32 patients. Estimated OS at 18 months after losing RBC TI was 51% ± 22%.

To ascertain the influence of lenalidomide in the subset of lower-risk MDS with del(5q) and RBC transfusion-dependency, we compared the outcome in terms of OS and risk of progression to AML of the group of 65 RBC transfusion-dependent patients at the start of lenalidomide and the group of 62 patients with RBC transfusion dependency at any time point during the course of their disease but who did not receive the drug. As in the overall series, lenalidomide treatment was strongly associated with potential confounding variables such as WBC and platelet counts, RBC transfusion dependency at diagnosis and serum ferritin levels (Table 3). As shown in Fig 2, treatment with lenalidomide did not show a significant effect on OS or risk of AML evolution among RBC transfusion-dependent patients, both in univariate (OS: HR, 0·70; 95% CI, 0·38–1·28; = 0·25; and AML risk: HR, 1·12; 95% CI, 0·48–2·60; = 0·79, respectively) and multivariate analyses (OS: HR, 0·78; 95% CI, 0·42–1·44; = 0·43; and AML risk: HR, 1·41; 95% CI, 0·60–3·33; = 0·43, respectively).

Table 3. Main demographic, clinical and biological characteristics at diagnosis in the overall series of 127 RBC transfusion-dependent lower risk MDS patients with del(5q) according to lenalidomide treatment.
CharacteristicPatients not treated with lenalidomide (n = 62)Patients treated with lenalidomide (n = 65)P value
  1. P values denotes differences between patients receiving or not lenalidomide for the corresponding characteristic; WBC, white blood cell; WHO, World Health Organization; RCUD – RA, refractory cytopenia with unilineage dysplasia – refractory anaemia; RARS, RA with ring sideroblasts; RCMD, refractory cytopenia with multilineage dysplasia; RAEB-1, RA with excess blasts type 1; MDS, myelodysplastic syndromes; MDS/MPN, myelodysplastic/myeloproliferative neoplasms; LDH, lactate dehydrogenase; EPO, erythropoietin; RBC, red blood cell; IPSS, International Prognostic Scoring system; WPSS, WHO-based Prognostic Scoring system.

  2. a

    Mann–Whitney U-test.

  3. b

    Fisher's exact test.

  4. c

    Percentage of dyserythropoiesis was available in 43 patients (28 receiving lenalidomide and 15 not receiving lenalidomide).

  5. d

    Percentage of dysgranulopoiesis was available in 50 patients (32 receiving lenalidomide and 18 not receiving lenalidomide).

  6. e

    Percentage of dysthrombopoiesis was available in 54 patients (32 receiving lenalidomide and 22 not receiving lenalidomide).

  7. f

    LDH serum level was available in 92 patients (49 receiving lenalidomide and 43 not receiving lenalidomide).

  8. g

    Ferritin serum level was available in 84 patients (49 receiving lenalidomide and 35 not receiving lenalidomide).

  9. h

    EPO serum level was available in 69 patients (40 receiving lenalidomide and 29 not receiving lenalidomide).

  10. i

    RBC transfusion dependency was defined as having at least one RBC transfusion every 8 weeks over a period of 4 months.

  11. j

    RBC transfusion dependence at diagnosis was available in 122 patients (60 receiving lenalidomide and 62 not receiving lenalidomide).

  12. k

    WPSS risk category at diagnosis was available in 81 patients (29 receiving lenalidomide and 52 not receiving lenalidomide).

Age, median (range), years72 (37–90)69 (35–89)0·079a
<60 years, n (%)9 (14)18 (28)0·110b
≥60 years, n (%)53 (86)47 (72)
Female gender, n (%)41 (66)47 (72)0·574b
Haemoglobin, median (range), g/l96 (40–140)88 (30–120)0·112a
<100 g/l, n (%)38 (61)49 (75)0·129b
≥100 g/l, n (%)24 (39)16 (25)
WBC count, median (range), ×109/l4·6 (1·6–20)4·0 (1·7–9·0)0·046a
<4 × 109/l, n (%)21 (34)32 (50)0·115b
≥4 × 109/l, n (%)41 (66)33 (50)
Neutrophil count, median(range), ×109/l2·2 (0·08–14)1·9 (0·02–6·9)0·195a
<1·8 × 109/l, n (%)23 (37)31 (48)0·304b
≥1·8 × 109/l, n (%)39 (63)34 (52)
Platelet count, median (range), ×109/l255 (15–1000)270 (53–1161)0·196a
<150 × 109/l, n (%)20 (32)7 (11)0·006b
≥150 × 109/l, n (%)42 (68)58 (89)
Percentage of bone marrow blasts, n (%)
0–444 (71)54 (83)0·233b
5–1018 (29)11 (17)
Dyserythropoiesis,c median (range),%8 (0–100)20 (0–75)0·158a
Dysgranulopoiesis,d median (range),%9 (0–76)23 (0–100)0·036a
Dysthrombopoiesis,e median (range),%35 (0–85)70 (0–100)0·022a
WHO classification subtype, n (%)
RCUD – RA2 (3)0 (0)0·796b
RARS1 (2)1 (0)
RCMD15 (24)14 (22)
RAEB-17 (11)9 (14)
MDS associated with isolated del(5q)34 (55)38 (59)
MDS – unclassified1 (2)2 (3)
MDS/MPN2 (3)1 (2)
LDH serum level,f median (range), u/l294 (30–555)347 (104–1113)0·041a
Ferritin serum level,g median (range), μg/l190 (42–4732)291 (43–1390)0·110a
<500 μg/l, n (%)30 (86)33 (67)0·097b
≥500 μg/l, n (%)5 (14)16 (33)
EPO serum level,h median (range), u/l156 (32–1820)244 (28–1540)0·229a
Chromosomal abnormalities, n (%)
del(5q) alone47 (76)52 (80)0·589b
del(5q) + 1 additional abnormality8 (13)9 (14)
del(5q) + 2 or more additional abnormalities7 (11)4 (6)
RBC transfusion dependency,i,j n (%)26 (42)37 (62)0·0131b
IPSS risk category, n (%)
Low24 (39)24 (37)0·836b
Intermediate-138 (61)41 (63)
WPSS risk categoryk, n (%)
Very low16 (31)3 (10)0·0888b
Low19 (37)19 (66)
Intermediate7 (14)4 (14)
High8 (15)3 (10)
Very high2 (4)0 (0)
Figure 2.

Unadjusted time-dependent actuarial curves of OS and progression to AML in 127 patients with lower-risk MDS with del(5q) and RBC transfusion dependency according to lenalidomide treatment (lenalidomide, n = 65; no lenalidomide, n = 62). (A) Probability of OS. (B) Cumulative probability of progression to AML. Solid lines (──) indicate lenalidomide treatment (n = 65) and dashed lines (- - -) denote no lenalidomide treatment (n = 127). Patients treated with lenalidomide (n = 65) are included in both actuarial curves (see “'Statistical analysis'” for details). P values were assessed by likelihood ratio tests obtained in the first step of a forward selection procedure of Cox's proportional hazards regression model with lenalidomide treatment included as time-dependent covariate. OS, overall survival; SD, standard deviation; AML, acute myeloid leukaemia; MDS, myelodysplasic syndrome; RBC, red blood cell.

Then, we compared OS and risk of AML evolution between the group of 51 patients who achieved RBC TI with lenalidomide and the group of 62 RBC transfusion-dependent patients not treated with lenalidomide. As depicted in Fig 3A, RBC TI patients after lenalidomide treatment had a statistically significant better OS in univariate analysis (HR, 0·41; 95% CI, 0·19–0·89; = 0·023) and this group showed a trend for longer OS in multivariate analyses (HR; 0·49; 95% CI, 0·23–1·06; = 0·069). The risk of AML evolution for both cohorts of patients was not significantly different in univariate (HR, 0·60, 95% CI, 0·20–1·78; = 0·35; Fig 3B) and multivariate analyses (HR; 0·80; 95% CI, 0·26–2·47; = 0·70).

Figure 3.

Unadjusted time-dependent actuarial curves of OS and progression to AML in 113 patients with lower-risk MDS with del(5q) and RBC transfusion dependency comparing patients achieving RBC transfusion independency (TI) after lenalidomide (n = 51) and untreated patients (n = 62). (A) Probability of OS. (B) Cumulative probability of progression to AML. Solid lines (──) indicate lenalidomide treatment (n = 51) and dashed lines (- - -) denote no lenalidomide treatment (n = 113). Patients treated with lenalidomide (n = 51) are included in both actuarial curves (see “'Statistical analysis'” for details). P values were assessed by likelihood ratio tests obtained in the first step of a forward selection procedure of Cox's proportional hazards regression model with lenalidomide treatment included as time-dependent covariate. OS, overall survival; SD, standard deviation; AML, acute myeloid leukaemia; MDS, myelodysplasic syndrome; RBC, red blood cell.

Effect of lenalidomide therapy in patients showing a cytogenetic response

Cytogenetic response was assessed in 49 patients. Nineteen (39%) had a complete cytogenetic response, 10 (20%) a partial cytogenetic response and 20 (41%) did not show any cytogenetic response. New chromosomal abnormalities during follow-up were detected in six patients (12%).

Patients attaining a cytogenetic response with lenalidomide (n = 29) had a significantly longer OS than untreated patients (n = 129) in univariate (HR, 0·16; 95% CI, 0·39–0·66; = 0·011; Fig 4A) and multivariate analysis (HR, 0·19; 95% CI, 0·05–0·78; = 0·021). The risk of AML evolution of cytogenetic responders after lenalidomide and untreated patients was not significantly different in univariate (HR, 0·49; 95% CI, 0·12–2·07; = 0·33; Fig 4B) or multivariate analysis (HR, 0·49; 95% CI, 0·11–2·11; = 0·33).

Figure 4.

Unadjusted time-dependent actuarial curves of OS and progression to AML in patients with lower-risk MDS with del(5q) comparing patients treated with lenalidomide who achieved cytogenetic response (n = 29) and untreated patients (n = 129). (A) Probability of OS. (B) Cumulative probability of progression to AML. Solid lines (──) indicate lenalidomide treatment (n = 29) and dashed lines (- - -) denote no lenalidomide treatment (n = 158). Patients treated with lenalidomide (n = 29) are included in both actuarial curves (see “'Statistical analysis'” for details). P values were assessed by likelihood ratio tests obtained in the first step of a forward selection procedure of Cox's proportional hazards regression model with lenalidomide treatment included as time-dependent covariate. OS, overall survival; SD, standard deviation; AML, acute myeloid leukaemia; MDS, myelodysplasic syndrome.

Discussion

This large retrospective comparative study in lower risk MDS patients with del(5q) did not reveal any significant impact of lenalidomide treatment in OS or AML risk in the overall series of patients or when the analysis was restricted to the smaller group of RBC transfusion-dependent patients. Nevertheless, those patients who attained RBC TI or, especially, who showed a cytogenetic response with lenalidomide had a substantial survival benefit. In contrast to other reports (Adès et al, 2012; Kuendgen et al, 2013) in this patient population, the current study assessed the effect of lenalidomide therapy on outcomes by multivariate time-dependent methodology in an attempt to account for two different kinds of biases: (i) starting treatment with lenalidomide at different time points after diagnosis and (ii) differences in biological characteristics with prognostic relevance among patients receiving or not lenalidomide.

Not unexpectedly, given the retrospective nature of the current study, the two groups of patients defined according to lenalidomide therapy showed substantial disparities at presentation in important clinical and biological covariates (Kantarjian et al, 2009; Mallo et al, 2011; Adès et al, 2012; Germing et al, 2012; Kuendgen et al, 2013).These differences were probably due to the significantly more recent diagnosis of patients treated with lenalidomide and restricted access to lenalidomide through a compassionate use programme.

Outcomes in both cohorts of the current report were representative of those expected for this population of patients (Kantarjian et al, 2009; Mallo et al, 2011; Germing et al, 2012). Thus, OS and risk of AML progression in the group of untreated patients were closely similar to those observed in a previously published large multinational series that included many patients of this cohort (Mallo et al, 2011), and were just in between those reported in other two large series of untreated lower-risk MDS with del(5q) (Kantarjian et al, 2009; Germing et al, 2012). Variations in outcomes between published studies are probably due to differences in the incidence of unfavourable prognostic variables and in the starting point used for assessing OS length and AML risk. In fact, RBC transfusion dependency, excess of bone marrow blasts and intermediate-risk IPSS category were higher in the present series than in the series reported by Germing et al (2012) whereas in the series reported by Kantarjian et al (2009), OS was measured from the date of referral. On the other hand, OS length in the lenalidomide-treated group of the current study was closely similar to that reported in previous series (Fenaux et al, 2011; Adès et al, 2012; Kuendgen et al, 2013). Because of significant differences in statistical methodology (the risk of AML estimated by cumulative incidence methods in the presence of competing events is always inferior to the one assessed by cumulative probability), patient population and follow-up bone marrow evaluations, comparison of the risk of AML progression between published series in patients treated with lenalidomide is cumbersome. In the present study, actuarial time-dependent cumulative probabilities of AML progression at 2 and 5 years from diagnosis were 6% and 31%, respectively. In the MDS-004 randomized trial, cumulative probability of AML evolution for lenalidomide-treated patients was 17% at 2 years and 25% at 3 years from randomization (Fenaux et al, 2011). Cumulative incidence of AML progression in the Groupe Francophone des Myelodysplasies (GFM) report was 9% at 4 years from diagnosis (Adès et al, 2012) whereas in the multinational study that used left truncation methodology (Kuendgen et al, 2013) the 2- and 5-year cumulative incidences were 7% and 23%, respectively.

Consistent with previous reports (Kantarjian et al, 2009; Mallo et al, 2011; Germing et al, 2012), characteristics showing an independent association with outcomes in the present study included age, platelet count, number of chromosomal abnormalities, and percentage of blasts in bone marrow. All theses variables along with other powerful predictors of outcome in series of lower risk MDS patients with del(5q), (Kantarjian et al, 2009; Mallo et al, 2011; Germing et al, 2012) were included in all multivariate analyses.

The present study was unable to detect a significant effect of lenalidomide treatment on OS neither in the overall series nor in the smaller subset of RBC transfusion-dependent patients. The impact of lenalidomide on OS in the two other retrospective comparative studies currently available in RBC transfusion-dependent patients with lower-risk MDS and del(5q) (Adès et al, 2012; Kuendgen et al, 2013) differed. As in the current report, in the GFM retrospective series, which used a complex propensity score to try to match as much as possible their untreated control cohort (n = 71) to the lenalidomide-treated group (n = 95) and accounting for the time-dependent characteristic of treatment with lenalidomide by considering different initial time points for estimating survival in both cohorts (date of diagnosis for untreated and date of starting lenalidomide for treated patients, respectively), OS was similar in both cohorts (= 0·15) (Adès et al, 2012). In contrast, the retrospective multinational study, which compared a cohort of 295 lenalidomide-treated patients included in previous clinical trials in RBC transfusion-dependent patients with lower-risk MDS and del(5q) (List et al, 2006; Fenaux et al, 2011) with a historical untreated cohort of 125 similar patients and that used left truncation to adjust for study entry differences between cohorts, the lenalidomide-treated group had superior OS (Kuendgen et al, 2013).This effect on OS was not evident in univariate analysis (P = 0·76) and only become apparent in multivariate analysis (P = 0·012), which is surprising because baseline characteristics, except for a higher RBC transfusion burden in lenalidomide-treated patients, were well balanced across cohorts. Remarkably, the current as well as the two other comparative studies available did not show any significant impact of lenalidomide treatment on AML risk (Adès et al, 2012; Kuendgen et al, 2013).

In the current study, RBC TI rate with lenalidomide (78%) was higher than in previous reports (List et al, 2006; Fenaux et al, 2011), probably reflecting our less stringent definition of RBC transfusion dependency. The proportion of patients showing a cytogenetic response (59%) is in close agreement with published data (List et al, 2006; Fenaux et al, 2011). In the randomized trial of lenalidomide treatment in RBC transfusion-dependent patients with lower-risk MDS with del(5q), patients showing a RBC-TI response with lenalidomide had longer OS and AML-free survival than RBC-TI non-responders, and there was also a trend for better OS for cytogenetic responders after lenalidomide compared with cytogenetic non-responders (Fenaux et al, 2011). The current study shows for the first time that patients responding to lenalidomide, in terms of achievement of RBC TI or cytogenetic response, have superior OS than patients not receiving lenalidomide.

The results reported herein have clinical relevance and deserve close attention. The benefit of lenalidomide treatment in lower-risk MDS patients with del(5q) seems to be limited to patients having an erythroid or cytogenetic response. Further, an elegant study has showed the persistence of stem cells carrying del(5q) in most patients in cytogenetic remission after lenalidomide treatment, suggesting that lenalidomide alone does not cure MDS with del(5q) (Jädersten et al, 2009). Thus, identification of biomarkers of response to lenalidomide is important. In the randomized trial of lenalidomide in RBC transfusion-dependent patients with lower-risk MDS with del(5q), a baseline platelet count ≥150 × 109/l was independently associated with achievement of RBC-TI (Fenaux et al, 2011). In the current study, as in another large series (Mallo et al, 2011), this platelet count threshold was strongly associated with OS and AML risk in every subset of patients analysed. On the other hand, recent evidence has shown that the presence of TP53 gene mutations, even in a very small population of clonal cells, occurs in up to 20% of lower-risk MDS with del(5q) (Jädersten et al, 2011; Sebaa et al, 2012) and is highly predictive of both a lower response rate to lenalidomide and a greater risk of progression to AML. Both characteristics, platelet count and TP53 mutations, could prove useful for decision-making regarding the use of lenalidomide in lower-risk MDS with del(5q). The best method to assess the presence of TP53 mutations is currently undefined. The 2% threshold in bone marrow progenitor cells expressing TP53 protein by immunohistochemistry to consider a sample as positive for TP53 gene mutations (Sebaa et al, 2012) seems hardly reproducible. Further, direct or sensitive deep-sequencing of TP53 gene mutations (Tehranchi et al, 2010; Sebaa et al, 2012) would be cumbersome and not readily available in many centres that treat MDS patients. Obviously, a platelet count threshold, although probably less sensitive than TP53 mutations, would be simpler to use. The potential correlation between presence of TP53 mutations and platelet count has not been assessed.

Another point that should be highlighted is the poor prognosis of patients failing to respond to lenalidomide or progressing after lenalidomide treatment (Fenaux et al, 2011). The median OS for this cohort is closer to that expected for patients with higher-risk MDS (Greenberg et al, 1997), suggesting those patients should be seriously considered for therapies capable of altering the natural course of the disease (i.e. haematopoietic stem cell transplantation or hypomethylating agents).

To sum up, with all the limitations of a retrospective study but using an adequate methodology to avoid potential biases, the current report clearly shows that lenalidomide treatment does not obviously impact long-term outcomes of lower-risk MDS patients with del(5q) except in the subset of patients showing RBC-TI or cytogenetic responses, who seem to have a significant survival advantage.

Acknowledgements

This work was supported in part by research funding from “RTICC” (Red Temática de Investigación Cooperativa en Cáncer, RD06/0020/0031, RD07/0020/2004), Instituto de Salud Carlos III, Ministerio de Sanidad y Consumo, Spain (FI07/00107; PI07/1009 and PI11/02010). The GESMD wishes to thank Grupo Andaluz de Síndromes Mielodisplásicos for its strong cooperation in the study and the Spanish PETHEMA Foundation for support in the maintenance of the GESMD database. The authors are also grateful to Luis Benlloch, data manager of GESMD, for capture and assembly of all data for analysis.

Author's contributions

J.S.-G. and G.S. designed and performed the research, collected, assembled, analysed, and interpreted the data, and wrote the manuscript, C.d.-C., B.N., R.d.-P. B.X., D.V., S.B., V.M.-B., M.G.-P., P.F., M.T., A.B., C.C., F.R., M.D.-C. B.A. G.A., J.B., M.-J.A., J.F., and J.S.-L. performed the research and collected the data, E.L. and E.S. performed the research, collected the data, and reviewed cytogenetic information, and I.L. performed the research and assembled and analysed the data. All authors critically reviewed the manuscript and approved the final draft of the paper.

Conflict of interest disclosure

J.S-G. has received honoraria and research funding from Celgene and Novartis, C.d.-C. has received honoraria and research funding and is on the advisory committee for Celgene. F.R. has received honoraria from Amgen, Celgene, Merck Sharp and Dohme, Novartis, Pfizer and Roche, research funding from Celgene and is on the advisory committee for Celgene. B.N. and J.B. have received honoraria and are on the advisory committee for Celgene. G.S. has received honoraria and research funding from Celgene, Novartis, and Amgen and is on the advisory committee for Amgen, Böehringer-Ingelheim, Celgene, Merck Sharp and Dohme, and Novartis. The remaining authors declare no competing financial interests.

Appendix 1

The following institutions and investigators from the GESMD participated in the study: Hospital Universitario Reina Sofia, Córdoba (J Sánchez-García, J Serrano-López, J Casaño), Hospital Universitario de Salamanca, Salamanca (C del Cañizo, M Diez-Campelo, JR González, JM Hernández-Rivas); Hospital Universitario La Fe, Valencia (G Sanz, E. Such, J Cervera, L. Senent, I Lorenzo); Hospital Clinic, Barcelona (B Nomdedeu, X Calvo, M Belkaid, D Costa, M Nomdedeu); Hospital Central de Asturias, Oviedo (E Luño, T Bernal, C. Sanzo); Hospital Universitario La Paz, Madrid (R de Paz, D Hernández-Maraver); Institut Català d'Oncologia, Josep Carreras Research Institute-Hospital Germans Trias i Pujol, Badalona (B. Xicoy, J Jiménez, F Millá); Hospital Universitario Vall D'Hebron, Barcelona (D Valcarcel, T Vallespí); Hospital Sant Pau, Universitat Autónoma Barcelona (S Brunet, JF Nomdedeu); Hospital Arnau de Vilanova, Lleida (V Marco); Consorci Sanitari Terrassa, Terrassa (M García-Pintos); Hospital General Universitario Gregorio Marañón, Madrid (P Font, S Osorio); Hospital Clínico Universitario, Instituto de Investigación INCLIVA, Valencia (M Tormo, M Calabuig); Hospital Carlos Haya, Málaga (A. Bailén); Hospital Virgen de la Luz, Cuenca (CJ Cerveró); Hospital Universitario de León and IBIOMED (Universidad de León), León (F Ramos); Hospital Universitario de Cruces, Baracaldo (B Arrizabalaga); Hospital Clinico Universitario Lozano Blesa, Zaragoza (G Azaceta); Hospital Son Llatzer, Palma de Mallorca (J Bargay); Hospital de Sagunto, Sagunto (MJ Arilla); Hospital Insular de Gran Canaria, Las Palmas de Gran Canaria (M Caballero); Hospital Universitario Virgen del Rocio, Sevilla (J Falantes); Hospital del Mar, Barcelona (C Pedro); Hospital Univeristario 12 de Octubre, Madrid (J Martínez-López); Hospital Txagorritxu, Vitoria (MT Ardanaz); Hospital General Universitario, Valencia (R Collado); Hospital Universitario Puerta del Mar, Cadiz (JA Muñoz); Hospital Dr. Peset, Valencia (R Andreu); Hospital Clínico San Carlos, Madrid (C Benavente); Hospital Marques de Valdecilla, Santander (A Insunza); Hospital Morales Meseguer, Murcia (ML Amigo); Hospital Severo Ochoa, Madrid (MJ Requena); Hospital Valle de los Pedroches, Pozoblanco (R Ríos); Fundación Hospital de Alcorcón, Madrid (L Villalón); Hospital de Cabueñes, Gijón (A Fernández-González); Hospital de la Ribera, Alcira (S Bonanad); Hospital General de Elche, Elche (A Marco); Hospital Infanta Sofia, Murcia (A Mora); Hospital Dr. Josep Trueta, Girona (R Coll); Hospita Povisa, Vigo (A Simiele); Hospital Universitario de Canarias, Santa Cruz de Tenerife (B González); Hospital Hospital de La Princesa, Madrid (V Gómez); Universidad de Navarra, Pamplona (MJ Calasanz); Hospital Duran i Reynals, L'Hospitalet (R Duarte) and Hospital Puerta de Hierro, Madrid (G Bautista).

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