Leukemia & Lymphoma, July 2014; 55(7): 1584–1590 © 2014 Informa UK, Ltd. ISSN: 1042-8194 print / 1029-2403 online DOI: 10.3109/10428194.2013.850167
ORIGINAL ARTICLE: CLINICAL
Soluble interleukin-2 receptor level predicts survival in patients with follicular lymphoma treated with cyclophosphamide, doxorubicin, vincristine and prednisone chemotherapy in the rituximab era Vít Procházka1, Tomáš Papajík1, Edgar Faber1, Luděk Raida1, Zuzana Kapitáňová1, Kateřina Langová2, Zuzana Prouzová3, Marie Jarošová1 & Karel Indrák1 1Department of Hemato-Oncology, 2Department of Medical Biophysics and 3Department of Clinical and Molecular Pathology,
Faculty of Medicine and Dentistry, Palacky University, Olomouc, Czech Republic
has dramatically improved over the last decade, especially after the introduction of targeted therapy with monoclonal antibodies [3]. For years, risk assessment in patients with FL was based on five independent prognostic parameters contained in the Follicular Lymphoma International Prognostic Index (FLIPI). The index is composed of the following variables: age over 60 years, lactate dehydrogenase level above the upper limit of normal, involvement of more than four lymph node groups, hemoglobin (Hb) level of less than 120 g/L and advanced stage of the disease (Ann Arbor classification). The FLIPI is used to distribute patients evenly into three different prognostic groups: low, intermediate and high risk [4]. The predictive value of the FLIPI was confirmed by a large number of prospective studies of both untreated [5,6] and relapsed patients [7]. Although the FLIPI score is used globally as the gold standard, its historical and methodological limitations must be considered. First, the FLIPI was created in the pre-rituximab era, i.e. at a time when only a few patients were treated with intensive (high-dose) anthracycline-based chemotherapy and autologous stem cell transplant. In these patient groups, the predictive value of the index may be limited. Another problem is the FLIPI endpoint, i.e. overall survival (OS). It is possible that if progression-free survival (PFS) was assessed, the score would include other variables as well. Moreover, from a current perspective, PFS is a much more practical tool for comparing the individual treatment modalities in indolent lymphoma. With better (longer) survival of patients with FL, studies with OS as the endpoint would take a rather long time. The above reasons led to an effort to create a new index comprising all the relevant modern prognostic factors and primarily concerned with PFS. In 2009, a working group led by Professor Solal-Céligny, one of the authors of the original FLIPI, published a draft of a new index, FLIPI-2 [8].
Abstract This study analyzed the prognostic significance of soluble interleukin-2 receptor a (sIL-2Ra) levels in 100 prospectively enrolled patients with previously untreated follicular lymphoma. It showed that sIL-2Ra level 115 pmol/L at the time of treatment initiation correlated with a high Follicular Lymphoma International Prognostic Index-2 (FLIPI-2), bulky disease, advanced clinical stage, number of involved lymph nodes, bone marrow involvement and elevated b2-microglobulin (B2M) level. When testing all patients, sIL-2Ra 115 pmol/L was associated with significantly shorter progression-free (PFS; p 0.03, hazard ratio [HR] 2.04) but not overall (OS; p 0.06, HR 2.36) survival rates. Subanalysis of patients receiving cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) rituximab showed higher predictive power for both PFS (HR 2.75, 95% confidence interval [CI] 1.24–6.11, p 0.01) and OS (HR 3.33, 95% CI 1.15–9.63, p 0.02). In the whole population (n 100), only B2M proved a significant univariate predictor (p 0.007, HR 2.8) of PFS. When testing patients treated with CHOP rituximab, sIL-2Ra was found to be the best univariate predictor for PFS among all FLIPI-2 factors (HR 2.68, p 0.015). Serum IL-2Ra levels may help to refine risk assessment in the modern immunotherapy era complementary to FLIPI-2 factors. Keywords: Follicular lymphoma, chemotherapy, autologous transplant, interleukin, rituximab, CHOP
Introduction Follicular lymphoma (FL) accounts for about 20–30% of all non-Hodgkin lymphomas (NHL) in Western Europe and the USA [1]. In Central Europe (the Czech Republic) the incidence is about 19%, as seen from the Czech Lymphoma Study Group registry data [2]. Although FL is a clinically and biologically heterogeneous disease, the outcome for patients
Correspondence: Tomáš Papajík, MD, Ass. Prof. Department of Hemato-Oncology, Faculty of Medicine and Dentistry, Palacky University Olomouc, I. P. Pavlova 6, 77520 Olomouc, Czech Republic. Tel: 420588443200. Fax: 420585428102. E-mail: [email protected] Received 3 August 2013; revised 11 November 2013; accepted 24 September 2013
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IL-2 receptor in follicular lymphoma Compared with the FLIPI, the FLIPI-2 places emphasis on as precise an assessment of tumor mass as possible. The FLIPI-2 score was validated in an independent series of patients with FL [9]. Clinical heterogeneity and implementation of novel treatment approaches including risk-adapted therapy justify a need for novel specific prognostic factors for patients with FL. One of the promising prognostic tools in the assessment of patients with FL is an exploration of the role of normal T-cells in the tumor microenvironment, which have a substantial impact on antitumor immunity and patient outcome [10,11]. Recent studies have highlighted the significance of CD4 CD25 Foxp3 regulatory T-cells (Tregs) in the immune response and in the regulation of antitumor immunity. In FL, intratumoral Tregs are present in significant numbers in biopsy specimens, and markedly inhibit the proliferation and cytokine or granule production of intratumoral CD4 and CD8 T cells [12,13]. The key cytokine originally identified as a T-cell growth factor is interleukin-2 (IL-2) [14]. IL-2 is essential in the development of Tregs, and in the absence of IL-2, Tregs cannot survive or expand in the thymus or in the peripheral blood. Furthermore, IL-2 is directly required for Treg function, and in its absence, Tregs fail to suppress T-cell proliferation [15,16]. IL-2 exerts its effect through binding to its receptor on the cell surface. IL-2 receptor (IL-2R) is composed of three different subunits: α, β and γ. In addition to membrane receptors, several studies have demonstrated the existence of a truncated, soluble form of IL-2Rα that is generated exclusively by the proteolytic cleavage of membrane IL-2Rα [17]. It has been found that the levels of soluble IL-2Rα (sIL-2Rα) are elevated in serum from patients with a variety of cancers, and the levels of sIL2Rα in serum have proven to be useful markers of disease activity [18]. So far, only one study has been performed in patients with FL to establish the role of soluble IL-2Rα. Zhi-Zhang Yang and colleagues performed a comprehensive study, and found that sIL-2Rα facilitates IL-2 signaling and induces Foxp3 expression in T cells, and that sIL-2Rα synergizes with IL-2 to suppress antitumor immunity by suppressing the proliferation and granule production by intratumoral effector T cells [19]. These results indicate that sIL-2Rα plays an active biological role in FL by binding IL-2 and promoting IL-2 signaling rather than depleting IL-2 and blocking its function. When testing 33 previously untreated patients with FL who received rituximab monotherapy, sIL-2Rα serum levels independently predicted progression-free survival (p 0.006). The prognostic impact of sIL2-Rα in a large cohort of patients with FL treated with chemotherapy has not yet been established. This study analyzed the prognostic significance of sIL-2Rα levels in 100 prospectively enrolled patients with previously untreated FL.
Materials and methods Patient study group A total of 100 prospectively enrolled patients with FL with lymphoma grades I–IIIa treated at the Department of
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Table I. Correlation between sIL-2Rα levels and clinical features of 100 patients with follicular lymphoma. Characteristic Age (years) 60 60 Gender Male Female Clinical stage Limited (I/II) Advanced (III/IV) Systemic symptoms Present Absent Tumor bulk 7 cm Present Absent LDH level Below the limit Above the limit Hb level 120 g/L 120 g/L Bone marrow Involved Not involved B2M level 3 mg/L 3 mg/L FLIPI score Low Intermediate High FLIPI-2 score Low Intermediate High
sIL-2Rα 115 pmol/L
sIL-2Rα 115 pmol/L
16 29
17 38
0.62
13 32
17 38
0.83
19 26
6 49
0.001
13 32
20 35
0.15
11 33
38 15
0.001
31 14
32 23
0.27
5 40
11 44
0.23
14 31
39 16
0.001
35 10
20 34
0.001
24 12 9
6 18 31
0.001
31 8 6
10 13 32
0.001
p-Value
sIL-2Rα, soluble interleukin-2 receptor α; LDH, lactate dehydrogenase; Hb, hemoglobin; B2M, β2-microglobulin; FLIPI, Follicular Lymphoma International Prognostic Index.
Hemato-Oncology, University Hospital Olomouc between November 1998 and March 2010 were analyzed. In all patients, the diagnosis of NHL was based on readings of biopsy specimens and confirmed by a university center hematopathologist according to the World Health Organization (WHO) “classification of tumours of haematopoietic and lymphoid tissues.” This study was approved by the institutional independent ethics committee and performed in accordance with the Declaration of Helsinki. Tables I and II show baseline clinical characteristics.
Table II. Clinical features of 55 patients with follicular lymphoma treated with CHOP rituximab therapy. n 55 (100%) Age (median, range) Age 60 years Advanced clinical stage (III/IV) Systemic symptoms (present) Tumor bulk 6 cm Bone marrow involvement B2M level UNL sIL-2Rα 115 pmol/L FLIPI-2 score: low/intermediate/high
59 years (34–79) 23 (42%) 41 (75%) 21 (38%) 24 (44%) 22 (40%) 33 (60%) 25 (45%) 10 (18%)/24 (44%)/21 (38%)
CHOP, cyclophosphamide, doxorubicin, vincristine, prednisone; B2M, β2-microglobulin; sIL-2Rα, soluble interleukin-2 receptor α; FLIPI-2, Follicular Lymphoma International Prognostic Index-2.
1586 V. Procházka et al. 34 (38%) of the chemotherapy-treated patients. Twentynine of them received R (375 mg/m2 every 3 months for 24 months), five patients were treated with interferon α (3 106 IU three times per week for 24 months). Five patients received consolidation with ibritumomab tiuxetan (in three of them followed by R maintenance).
Chemotherapy protocols Figure 1. Scheme of the treatment arms.
Laboratory analyses Laboratory analyses were carried out using fresh blood samples collected on the day of diagnosis. The serum concentration of IL-2Rα was quantified with an enzyme-linked immunosorbent assay (ELISA) using the sIL-2Rα Immunotech Kit (Immunotech, Marseilles, France) and a SpectraCount (Packard BioInstruments, USA) reader with a measuring range of 5–400 pmol/L. A cut-off was set at a value of 115 pmol/L (sensitivity 0.683, 1 specificity 0.475) as identified using receiver operating characteristic (ROC) analysis. Area under the ROC curve (AUC) was 0.604 with standard error 0.057. The asymptotic significance of the AUC reached 0.078 (asymptotic 95% confidence interval [CI] 0.493–0.715).
Treatment Eleven patients (11%) did not fulfill the GELF (Groupe d’Etude des Lymphomes Folliculaires) criteria for systemic treatment initiation [20]. These patients – all with a limited disease stage – were observed (watch and wait policy, n 6) or treated with local involved-field radiotherapy (n 5). Eighty-nine patients (89%) were treated with chemotherapy (Figure 1). Fifty-two patients (58.4%) were able to receive therapy with lymphoma risk-appropriate intensity, whereas 37 patients (41.6%) were treated irrespective of the disease risk (standard cyclophosphamide, doxorubicin, vincristine, prednisone [CHOP] or CHOP-like therapy in 32 and sequential chemotherapy in five of the patients). Front-line treatment of the 52 suitable patients was stratified according to the commonly used risk factors (FLIPI, β2-microglobulin [B2M] and serum thymidine kinase levels, bulky disease) and with regard to age and comorbidities into three treatment groups (Table III). Rituximab was added to front-line chemotherapy in 66 (74%) of the chemotherapy-treated patients. Maintenance treatment after front-line therapy was indicated in
CHOP and ProMACE-CytaBOM (prednisone, doxorubicin, cyclophosphamide, etoposide, cytarabine, bleomycin, vincristine, methotrexate, leucovorin) protocols were administered as previously published [21,22]. The sequential chemotherapy protocol consisted of three cycles of a CHOEP21-like regimen (PACEBO), one cycle of an ifosfamide and methotrexate-based regimen (IVAM) and a priming regimen with high-dose cytosine arabinoside (HAM). The PACEBO regimen was administered as follows: doxorubicin 40 mg/m2 intravenously (IV), day 1; cyclophosphamide 850 mg/m2 IV, day 1; etoposide 200 mg/m2 IV, day 1; bleomycin 10 mg/m2 IV, day 8; vincristine 1.4 mg/m2 (maximum 2.0 mg) IV, day 8; and prednisone 40 mg/m2 orally, days 1–14. The IVAM regimen consisted of ifosfamide 1500 mg/m2 IV, days 1–5; etoposide 150 mg/m2 IV, days 1–3; cytosine arabinoside 100 mg/m2 IV, days 1–3; methotrexate 3 g/m2 IV, day 5; mesna prophylaxis 1200 mg IV, days 1–5; and leucovorin rescue 25 mg/m2 IV, from day 6/7 until the plasma methotrexate level was below 0.05 μmol/L. The HAM regimen was administered as follows: cytosine arabinoside 2 g/m2 twice daily IV, days 1 and 2; mitoxantrone 10 mg/m2, days 2 and 3 [23]. Stem cell mobilization was performed with 12 μg/kg of filgrastim given subcutaneously twice daily. The BEAM (BCNU, etoposide, cytarabine, melphalan) 200 conditioning regimen dosage was standard, as previously published [24].
Treatment response The treatment responses, classified as follows: complete response (CR), unconfirmed complete response (CRu), partial response (PR), stable disease (SD) and progressive disease (PD), were defined according to the International Workshop NHL Response Criteria published by Cheson et al. [25].
Statistical analysis The optimal cut-off point of the sIL-2Rα was identified with ROC analysis. The OS was defined as the time from diagnosis to the date of the last follow-up examination (censored) or the date of death (event) from any cause. The PFS was
Table III. Risk-adapted treatment stratification strategy (n 52). Risk group Low risk (n 23) Intermediate risk (n 8) High risk (n 21)
FLIPI FLIPI 0 FLIPI 1 FLIPI 1 FLIPI 2 FLIPI 3–5
Number of present additional risk factors 0–3 1–2 3 0–3 0–3
Treatment arm CHOP Sequential chemotherapy Sequential chemotherapy plus autologous stem cell transplant (BEAM)*
Rituximab added to induction 16 (69.6%) 8 (100%) 15 (71.4%)
FLIPI, Follicular Lymphoma International Prognostic Index; CHOP, cyclophosphamide, doxorubicin, vincristine, prednisone; BEAM, BCNU, etoposide, cytarabine, melphalan. *One patient received ProMACE-CytaBOM induction regimen instead of sequential chemotherapy due to historical reasons.
IL-2 receptor in follicular lymphoma
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defined as the date from first treatment to the date of documented disease progression or death from any cause (event) or the date of the last follow-up examination (censored). The Kaplan–Meier method was used to estimate the survival curves. The log-rank test was used to compare differences in survival times between patient subgroups. The relationship between sIL-2Rα levels (normal or elevated) and the standard prognostic factors were analyzed using the χ2 or Mann–Whitney U-test for qualitative or quantitative variables, respectively. A Cox proportional hazards model was used to assess the effects of the prognostic factors on OS or PFS. Both univariate and multivariate models were fitted. All significance levels were set to 0.05.
Results Analysis of treatment response and survival Treatment response was assessable in all 94 (100%) treated patients. CR or CRu was achieved in 78 (83.0%), PR in 13 (13.8%) and SD or PD in three (3.2%) of the patients. Patients with sIL-2Rα levels above 115 pmol/L had a lower, but not statistically significant, probability of CR achievement than patients with sIL-2Rα levels below the limit (78.2% vs. 86.8%, p 0.29). During the observation period, lymphoma relapsed in 36 patients (median time to relapse 26.2 months; range, 6.3–94.3 months) and 24 patients died (four of them in CR). After a median follow-up of 79.4 months (range 22–151 months), the OS of all patients reached 81.4% (95% CI 0.74–0.89) at 5 years. The PFS at 5 years reached 60.4% (95% CI 0.50–0.70); median time to progression was not reached. The 5-year PFS of patients with elevated sIL-2Rα level was 49.7% (95% CI 0.36–0.63), as compared to 70.9% (95% CI 0.57–0.85, p 0.03) in patients with sIL-2Rα below the limit (Figure 2). The 5-year OS of all patients with elevated sIL-2Rα levels was 74.0% (95% CI 0.62–0.86), as compared to 91.0% in patients with sIL-2Rα below the limit (95% CI 0.82–0.99, p 0.062) (Figure 3). Subanalysis of the 55 patients treated with CHOP or CHOP-like regimens showed superior 5-year PFS in patients
Figure 3. Overall survival curves, all patients. Patients with sIL-2Rα 115 pmol/L (black line), patients with sIL-2Rα 115 pmol/L (gray line), p 0.062.
with sIL-2Rα 115 pmol/L (68.6%, 95% CI 0.51–0.86) compared to those with sIL-2Rα 115 pmol/L (37.5%, 95% CI 0.18–0.57, p 0.01) (Table IV). Patients with lower sIL-2α levels also had much better OS at 5 years: 90.0% (95% CI 0.79–1.00) vs. 53.8% (95% CI 0.33–0.74, p 0.02). Rituximab (R) was added to CHOP equally in both groups: in 67% of cases in the low sIL-2Rα group and in 72% in the high sIL-Rα group (p 0.67). When focusing on the R-CHOP arm only (n 38), sIL-2Rα was still highly predictive for both PFS and OS. Five-year PFS in the low sIL-2Rα group was 84.4% (95% CI 0.68–1.00) compared to only 37.0% (95% CI 0.14–0.60, p 0.002) in the high sIL-2Rα group (Figure 4). Five-year OS in the low sIL-2Rα group reached 95.0% (95% CI 0.85–1.00), in contrast with only 38.9% (95% CI 0.13–0.64, p 0.0004) in patients with high sIL-2Rα levels (Figure 5, Table IV). On the other hand, patients with high-risk FL treated with more intensive protocols with (n 21) or without (n 13) autologous stem cell transplant consolidation did not have a different outcome regarding sIL-2Rα levels. No difference was seen in terms of OS (p 0.36) or PFS (p 0.98, data not shown).
Univariate and multivariate analyses
Figure 2. Progression-free survival curves, all patients. Patients with sIL-2Rα 115 pmol/L (black line), patients with sIL-2Rα 115 pmol/L (gray line), p 0.03.
We have shown that sIL-2Rα levels stratify patients well with respect to OS and PFS, both in the whole population and in the subgroup treated with CHOP-like regimens. There is a natural question regarding how good a predictor sIL-2Rα is with respect to the traditional predictors composing the FLIPI-2 index. To this end, we performed both univariate and multivariate Cox regression models. The FLIPI-2 index incorporates five dichotomic predictors: age over 60 years, bulky disease ( 6 cm), involvement of bone marrow, hemoglobin level less than 120 g/L and elevated B2M. The presence of any of these five factors adds one point to the FLIPI-2 index. Patients are stratified into three groups: low risk (FLIPI-2 0 points), intermediate risk (FLIPI-2 1–2 points) and high risk (FLIPI-2 3 points). We first assessed the predictive power of the FLIPI-2 variables. In the whole population (n 100), only B2M (out of the five FLIPI-2 predictors) proved to be a significant
1588 V. Procházka et al. Table IV. Survival of patients stratified according to sIL-2Rα level. All patients sIL-2Rα 115 sIL-2Rα 115 CHOP rituximab (n 55) sIL-2Rα 115 sIL-2Rα 115 R-CHOP (n 38) sIL-2Rα 115 sIL-2Rα 115
5-year OS
95% CI for OS
5-year PFS
95% CI for PFS
p-Value
81.4% 74.0% 91.0%
0.74–0.89 0.62–0.86 0.82–0.99
p-Value — 0.062
60.4% 49.7% 70.9%
0.50–0.70 0.36–0.63 0.57–0.85
— 0.03
53.8% 90.0%
0.33–0.74 0.79–1.00
0.02
37.5% 68.6%
0.18–0.57 0.51–0.86
0.01
38.9% 95.0%
0.13–0.64 0.85–1.00
0.001
37.0% 84.4%
0.14–0.60 0.68–1.00
0.002
sIL-2Rα, soluble interleukin-2 receptor α; CHOP, cyclophosphamide, doxorubicin, vincristine, prednisone; R-CHOP, rituximab-CHOP; OS, overall survival; CI, confidence interval; PFS, progression-free survival.
univariate predictor (p 0.007, hazard ratio [HR] 2.8) of PFS (Table V). The other four predictors were not significant. However, when the FLIPI-2 index (three-valued) was taken as the only predictor in the Cox proportional hazards model, the predictor was significant (p 0.0028), yielding an HR of 2.22 between the adjacent risk groups. Thus, the FLIPI-2 index retained the predictive power of the B2M predictor. The sIL-2Rα level as the only predictor of PFS yielded an HR of 2.02 (p 0.037), which is comparable to the predictive power of B2M (and thus also FLIPI-2). If we attempted to construct a multivariate Cox proportional hazards model, with a combination of any of the FLIPI-2 variables and the sIL-2Rα level as predictors, none of the predictors remained significant. The same type of analysis for the OS of the whole group (n 100) revealed that age (p 0.0061, HR 3.12) and B2M (p 0.0048, HR 8.03) were the only two significant univariate FLIPI-2 predictors of OS (Table VI). The high predictive power of B2M translated into the FLIPI-2 index. If the index was used as the only univariate predictor, it yielded an HR 3.75 (p 0.0021). In the case of OS, the sIL-2Rα level was not a significant univariate predictor (p 0.071). Multivariate analysis did not bring any new information. Turning to the subgroup of 54 patients who were treated with the CHOP regimen, in the case of PFS, the sIL-2Rα level proved to be the best univariate predictor (HR 2.68, p 0.015). Out of the five FLIPI-2 predictors, only the following two were significant: B2M (HR 2.45, p 0.043)
Figure 4. Progression-free survival curves of 55 patients treated with CHOP rituximab chemotherapy. Patients with sIL-2Rα 115 pmol/L (black line), patients with sIL-2Rα 115 pmol/L (gray line), p 0.002.
and bulk (HR 1.91, p 0.010). The FLIPI-2 index proved to be a significant univariate predictor (p 0.0073 and HR 2.30 between adjacent risk groups). Multivariate analysis did not bring any new information in this case. In the case of OS, we noted the high predictive power of B2M (HR 14.99, p 0.0088). Also bulk (HR 2.72, p 0.048) and age (HR 2.66, p 0.051) provided some predictive power, in the category of univariate FLIPI-2 predictors. The FLIPI-2 index yielded an HR 4.24 (p 0.0025) between the adjacent risk groups. The sIL-2Rα level was a significant univariate predictor (HR 3.33, p 0.027); however, its power was overshadowed by B2M. Multivariate analysis did not bring any new information in this case.
Discussion Our study is the first analysis of pretreatment serum IL-2Rα levels in a large FL population treated with chemotherapy R. We found serum IL-2Rα levels to be a significant predictor of PFS and with borderline significance also for OS in the whole population. The predictive power of sIL-2Rα strongly depends on the intensity of front-line chemotherapy. When testing patients treated with CHOP or CHOP-like regimens with or without R, sIL2Rα was found to be the best univariate predictor for PFS. Patients with sIL-2Rα 115 pmol/L showed almost double 5-year PFS (68.6%) compared to those with sIL-2α 115 pmol/L (37.5%). PFS advantage was translated into overall
Figure 5. Overall survival curves of 55 patients treated with CHOP rituximab chemotherapy. Patients with sIL-2Rα 115 pmol/L (black line), patients with sIL-2Rα 115 pmol/L (gray line), p 0.0004.
IL-2 receptor in follicular lymphoma Table V. Univariate models for progression-free survival, all patients (n 100). Variable Age (above 60) Bulk ( 6 cm) Bone marrow involvement Hemoglobin level ( 120 g/L) B2M level ( UNL)* sIL-2R level ( 115 pmol/L) FLIPI-2 (L vs. I vs. H)
Exp(B)
p-Value
95% CI
1.74 1.52 1.45 1.44 2.77 2.01 2.22
0.081 0.191 0.247 0.361 0.007 0.037 0.003
0.93–3.24 0.81–2.85 0.77–2.72 0.66–3.13 1.32–5.81 1.05–3.90 1.32–3.75
B2M, β2-microglobulin; sIL-2R, soluble interleukin-2 receptor; FLIPI-2, Follicular Lymphoma International Prognostic Index-2; L, low; I, intermediate; H, high; CI, confidence interval. *Upper normal limit 2.4 mg/L.
survival: OS at 5 years was 90.0% in the low sIL-2Rα group as compared to 53.8% in the high sIL-2Rα group. This survival advantage was retained even when analyzing the R-CHOP population. Patients with low sIL-2Rα level had overwhelmingly superior 5-year PFS (84.4% vs. 37.0%) and also 5-year OS (95.0% vs. 38.9%). On the other hand, when analyzing patients treated with more intensive treatment strategies including high-dose therapy and autologous stem cell transplant, the sIL-2Rα levels showed no prognostic role. The role of some conventional prognostic factors implemented into the FLIPI-2 score was only limited. Apart from age above 60 and B2M levels, none of the FLIPI-2 related parameters were found to be significant predictors in either univariate or multivariate analyses. When analyzing only patients treated with CHOP R, we found also a predictive power of bulk (PFS). In the context of FLIPI-2 factors sIL-2Rα level was found to be a predictor of OS and PFS irrespective of the population studied. Moreover, the sIL-2Rα level correlated strongly with well-known unfavorable parameters such as bulky disease, bone marrow involvement and B2M levels [26]. The prognostic value of serum sIL-2Rα assessment was confirmed in several clinical trials in the R era, but data are restricted to patients with diffuse large B-cell lymphoma treated with R-CHOP only. First, Goto and co-workers analyzed pretreatment levels of sIL-2Rα in 233 patients. With a cut-off level of 2000 U/mL, they found sIL-2Rα to be a predictor for both OS and PFS independent of IPI factors [27]. Second, Yamauchi and colleagues analyzed sIL-2Rα obtained after chemotherapy in 21 patients with diffuse large B-cell lymphoma (DLBCL) treated with R-CHOP therapy. They found elevated sIL-2Rα level to be a strong predictor for early disease relapse [28]. Similar
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results were obtained in a large retrospective study conducted by Ennishi and colleagues. They retrospectively analyzed 141 R-CHOP-treated patients. Those with low sIL-2Rα level (below median) had a much better 2-year event-free (92% vs. 66%, p 0.001) and also 2-year OS (95% vs. 82%, p 0.005) [29]. Third, Tomita and co-workers analyzed a novel prognostic index composed of three independent factors: sIL-2Rα (cutoff 2500 U/mL), clinical stage and LDH level (SIL). Their SIL index was tested in patients with DLBCL and was able to stratify patients into standard risk (5-year OS 91%) and high risk (5-year OS 67%) groups [30]. Very recently, the first article focusing on sIL-2R relevance in patients with FL was published. Yoshizato et al. found the sIL-2Rα level to be a predictor for PFS and time to next treatment. Unfortunately, the study group was rather small (n 54) and the follow-up short (up to 4 years) [31]. Although both the above studies and our data confirm the possible prognostic role of sIL-2Rα, uncertainty regarding the utility of sIL-2Rα in lymphoma still remains. First, there are many different laboratory techniques of sIL-2Rα measurement with different cut-off values. Second, prognostic power was confirmed only in patients treated with the R-CHOP regimen; different or more intensive regimens have not yet been tested. Finally, soluble IL-2Rα plays an important biological role in tumor immunosurveillance. This fact reflects the presence of advanced disease features such as bulky disease, high B2M and higher FLIPI/FLIPI-2 scores. A high level of sIL-2Rα should be considered a negative prognostic factor, complementary to the modern FLIPI-2, especially in patients treated with CHOP-like regimens in the R era.
Acknowledgements This study was supported by student project LF-2013-004 of the Faculty of Medicine and Dentistry, Palacky University, Olomouc. We would like to thank Mrs Kateˇrina Sicˇová and Mrs Lenka Prokopová for technical support, Mr. Pavel Kurfürst for English proofreading and Dr. Tomáš Fürst for statistical analyses.
Potential conflict of interest: Disclosure forms provided by the authors are available with the full text of this article at www.informahealthcare.com/lal.
Table VI. Univariate models for overall survival, all patients (n 100). Variable Age (above 60) Bulk ( 6 cm) Bone marrow involvement Hemoglobin level ( 120 g/L) B2M level ( UNL)* SIL-2R level ( 115 pmol/L) FLIPI-2 (L vs. I vs. H)
Exp(B)
p-Value
95% CI
3.12 1.83 1.36 2.34 8.03 2.36 3.75
0.006 0.164 0.468 0.063 0.005 0.071 0.002
1.38–7.05 0.78–4.28 0.59–3.15 0.96–5.74 1.89–34.2 0.93–6.00 1.61–8.74
B2M, β2-microglobulin; sIL-2R, soluble interleukin-2 receptor; FLIPI-2, Follicular Lymphoma International Prognostic Index-2; L, low; I, intermediate; H, high; CI, confidence interval. *Upper normal limit 2.4 mg/L.
References [1] Morton LM, Wang SS, Devesa SS, et al. Lymphoma incidence patterns by WHO subtype in the United States, 1992–2001. Blood 2006;107:265–276. [2] Trneˇný M, Vášová I, Pytlík R, et al. Klin Onkol 2007;20:341–348. [3] Swenson WT, Wooldridge JE, Lynch CF, et al. Improved survival of follicular lymphoma patients in the United States. J Clin Oncol 2005;23:5019–5026. [4] Solal-Celigny P, Roy P, Colombat P, et al. Follicular lymphoma international prognostic index. Blood 2004;104:1258–1265. [5] van de Schans SA , Steyerberg EW, Nijziel MR, et al. Validation, revision and extension of the Follicular Lymphoma International
1590 V. Procházka et al. Prognostic Index (FLIPI) in a population-based setting. Ann Oncol 2009;20:1697–1702. [6] Buske C, Hoster E, Dreyling M, et al. The Follicular Lymphoma International Prognostic Index (FLIPI) separates high-risk from intermediate- or low-risk patients with advanced-stage follicular lymphoma treated front-line with rituximab and the combination of cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) with respect to treatment outcome. Blood 2006;108: 1504–1508. [7] Montoto S, López-Guillermo A , Altés A , et al. Predictive value of Follicular Lymphoma International Prognostic Index (FLIPI) in patients with follicular lymphoma at first progression. Ann Oncol 2004;15:1484–1489. [8] Federico M, Bellei M, Marcheselli L, et al. Follicular lymphoma international prognostic index 2:a new prognostic index for follicular lymphoma developed by the international follicular lymphoma prognostic factor project. J Clin Oncol 2009;27:4555–4562. [9] Arcaini L, Merli M, Passamonti F, et al. Validation of follicular lymphoma international prognostic index 2 (FLIPI 2) score in an independent series of follicular lymphoma patients. Br J Haematol 2010;149:455–457. [10] Dave SS, Wright G, Tan B, et al. Prediction of survival in follicular lymphoma based on molecular features of tumor-infiltrating immune cells. N Engl J Med 2004;351:2159–2169. [11] Glas AM, Knoops L, Delahaye L, et al. Gene-expression and immunohistochemical study of specific T-cell subsets and accessory cell types in the transformation and prognosis of follicular lymphoma. J Clin Oncol 2007;25:390–398. [12] Yang ZZ, Novak AJ, Stenson MJ, et al. Intratumoral CD4 CD25 regulatory T-cell-mediated suppression of infiltrating CD4 T cells in B-cell non-Hodgkin lymphoma. Blood 2006;107:3639–3646. [13] Hilchey SP, De A , Rimsza LM, et al. Follicular lymphoma intratumoral CD4 CD25 GITR regulatory T cells potently suppress CD3/CD28-costimulated autologous and allogeneic CD8 CD25- and CD4 CD25- T cells. J Immunol 2007;178:4051–4061. [14] Liao W, Lin JX, Leonard WJ. Interleukin-2 at the crossroads of effector responses, tolerance, and immunotherapy. Immunity 2013;38:13–25. [15] Furtado GC, Curotto de Lafaille MA , Kutchukhidze N, et al. Interleukin 2 signaling is required for CD4() regulatory T-cell function. J Exp Med 2002;196:851–857. [16] de la Rosa M, Rutz S, Dorninger H, et al. Interleukin-2 is essential for CD4 CD25 regulatory T-cell function. Eur J Immunol 2004;34:2480–2488. [17] Rubin LA , Galli F, Greene WC, et al. The molecular basis for the generation of the human soluble interleukin 2 receptor. Cytokine 1990;2:330–336. [18] Murakami S. Soluble interleukin-2 receptor in cancer. Front Biosci 2004;9:3085–3090.
[19] Yang ZZ, Grote DM, Ziesmer SC, et al. Soluble IL-2Rα facilitates IL-2-mediated immune responses and predicts reduced survival in follicular B-cell non-Hodgkin lymphoma. Blood 2011; 118:2809–2820. [20] Decaudin D, Lepage E, Brousse N, et al. Low-grade stage III-IV follicular lymphoma: multivariate analysis of prognostic factors in 484 patients–a study of the groupe d’Etude des lymphomes de l’Adulte. J Clin Oncol 1999;17:2499–2505. [21] Fisher RI, Gaynor ER, Dahlberg S, et al. Comparison of a standard regimen (CHOP) with three intensive chemotherapy regimens for advanced non-Hodgkin’s lymphoma. N Engl J Med 1993;328: 1002–1006. [22] Federico M, Clo V, Brugiatelli M, et al. Efficacy of two different ProMACE-CytaBOM derived regimens in advanced aggressive nonHodgkin’s lymphoma. Final report of a multicenter trial conducted by GISL. Haematologica 1998;83:800–811. [23] Prochazka V, Faber E, Raida L, et al. Prolonged survival of patients with peripheral T-cell lymphoma after first-line intensive sequential chemotherapy with autologous stem cell transplantation. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2009;153:63–66. [24] Colombat P, Biron P, Laporte JP, et al. BEAM protocol and autologous bone marrow transplantation in first chemosensitive relapse of non-Hodgkin’s lymphomas. Eur J Cancer 1990;26:858. [25] Cheson BD, Horning SJ, Coiffier B, et al. Report of an international workshop to standardize response criteria for non-Hodgkin’s lymphomas. NCI Sponsored International Working Group. J Clin Oncol 1999;17:1244. [26] Solal-Céligny P, Cahu X, Cartron G. Follicular lymphoma prognostic factors in the modern era: what is clinically meaningful? Int J Hematol 2010;92:246–254. [27] Goto N, Tsurumi H, Goto H, et al. Serum soluble interleukin-2 receptor (sIL-2R) level is associated with the outcome of patients withdiffuse large B cell lymphoma treated with R-CHOP regimens. Ann Hematol 2012;91:705–714. [28] Yamauchi T, Matsuda Y, Takai M, et al. Early relapse is associated with high serum soluble interleukin-2 receptor after the sixth cycle of R-CHOP chemotherapy in patients with advanced diffuse large B-cell lymphoma. Anticancer Res 2012;32:5051–5057. [29] Ennishi D, Yokoyama M, Terui Y, et al. Soluble interleukin-2 receptor retains prognostic value in patients with diffuse large B-cell lymphoma receiving rituximab plus CHOP (RCHOP) therapy. Ann Oncol 2009;20:526–533. [30] Tomita N, Sakai R, Fujisawa S, et al. SIL index, comprising stage, soluble interleukin-2 receptor, and lactate dehydrogenase, is a useful prognostic predictor in diffuse large B-cell lymphoma. Cancer Sci 2012;103:1518–1523. [31] Yoshizato T, Nannya Y, Imai Y, et al. Clinical significance of serum-soluble interleukin-2 receptor in patients with follicular lymphoma. Clin Lymphoma Myeloma Leuk 2013;13:410–416.
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ORIGINAL ARTICLE: CLINICAL
Soluble interleukin-2 receptor level predicts survival in patients with follicular lymphoma treated with cyclophosphamide, doxorubicin, vincristine and prednisone chemotherapy in the rituximab era Vít Procházka1, Tomáš Papajík1, Edgar Faber1, Luděk Raida1, Zuzana Kapitáňová1, Kateřina Langová2, Zuzana Prouzová3, Marie Jarošová1 & Karel Indrák1 1Department of Hemato-Oncology, 2Department of Medical Biophysics and 3Department of Clinical and Molecular Pathology,
Faculty of Medicine and Dentistry, Palacky University, Olomouc, Czech Republic
has dramatically improved over the last decade, especially after the introduction of targeted therapy with monoclonal antibodies [3]. For years, risk assessment in patients with FL was based on five independent prognostic parameters contained in the Follicular Lymphoma International Prognostic Index (FLIPI). The index is composed of the following variables: age over 60 years, lactate dehydrogenase level above the upper limit of normal, involvement of more than four lymph node groups, hemoglobin (Hb) level of less than 120 g/L and advanced stage of the disease (Ann Arbor classification). The FLIPI is used to distribute patients evenly into three different prognostic groups: low, intermediate and high risk [4]. The predictive value of the FLIPI was confirmed by a large number of prospective studies of both untreated [5,6] and relapsed patients [7]. Although the FLIPI score is used globally as the gold standard, its historical and methodological limitations must be considered. First, the FLIPI was created in the pre-rituximab era, i.e. at a time when only a few patients were treated with intensive (high-dose) anthracycline-based chemotherapy and autologous stem cell transplant. In these patient groups, the predictive value of the index may be limited. Another problem is the FLIPI endpoint, i.e. overall survival (OS). It is possible that if progression-free survival (PFS) was assessed, the score would include other variables as well. Moreover, from a current perspective, PFS is a much more practical tool for comparing the individual treatment modalities in indolent lymphoma. With better (longer) survival of patients with FL, studies with OS as the endpoint would take a rather long time. The above reasons led to an effort to create a new index comprising all the relevant modern prognostic factors and primarily concerned with PFS. In 2009, a working group led by Professor Solal-Céligny, one of the authors of the original FLIPI, published a draft of a new index, FLIPI-2 [8].
Abstract This study analyzed the prognostic significance of soluble interleukin-2 receptor a (sIL-2Ra) levels in 100 prospectively enrolled patients with previously untreated follicular lymphoma. It showed that sIL-2Ra level 115 pmol/L at the time of treatment initiation correlated with a high Follicular Lymphoma International Prognostic Index-2 (FLIPI-2), bulky disease, advanced clinical stage, number of involved lymph nodes, bone marrow involvement and elevated b2-microglobulin (B2M) level. When testing all patients, sIL-2Ra 115 pmol/L was associated with significantly shorter progression-free (PFS; p 0.03, hazard ratio [HR] 2.04) but not overall (OS; p 0.06, HR 2.36) survival rates. Subanalysis of patients receiving cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) rituximab showed higher predictive power for both PFS (HR 2.75, 95% confidence interval [CI] 1.24–6.11, p 0.01) and OS (HR 3.33, 95% CI 1.15–9.63, p 0.02). In the whole population (n 100), only B2M proved a significant univariate predictor (p 0.007, HR 2.8) of PFS. When testing patients treated with CHOP rituximab, sIL-2Ra was found to be the best univariate predictor for PFS among all FLIPI-2 factors (HR 2.68, p 0.015). Serum IL-2Ra levels may help to refine risk assessment in the modern immunotherapy era complementary to FLIPI-2 factors. Keywords: Follicular lymphoma, chemotherapy, autologous transplant, interleukin, rituximab, CHOP
Introduction Follicular lymphoma (FL) accounts for about 20–30% of all non-Hodgkin lymphomas (NHL) in Western Europe and the USA [1]. In Central Europe (the Czech Republic) the incidence is about 19%, as seen from the Czech Lymphoma Study Group registry data [2]. Although FL is a clinically and biologically heterogeneous disease, the outcome for patients
Correspondence: Tomáš Papajík, MD, Ass. Prof. Department of Hemato-Oncology, Faculty of Medicine and Dentistry, Palacky University Olomouc, I. P. Pavlova 6, 77520 Olomouc, Czech Republic. Tel: 420588443200. Fax: 420585428102. E-mail: [email protected] Received 3 August 2013; revised 11 November 2013; accepted 24 September 2013
1584
IL-2 receptor in follicular lymphoma Compared with the FLIPI, the FLIPI-2 places emphasis on as precise an assessment of tumor mass as possible. The FLIPI-2 score was validated in an independent series of patients with FL [9]. Clinical heterogeneity and implementation of novel treatment approaches including risk-adapted therapy justify a need for novel specific prognostic factors for patients with FL. One of the promising prognostic tools in the assessment of patients with FL is an exploration of the role of normal T-cells in the tumor microenvironment, which have a substantial impact on antitumor immunity and patient outcome [10,11]. Recent studies have highlighted the significance of CD4 CD25 Foxp3 regulatory T-cells (Tregs) in the immune response and in the regulation of antitumor immunity. In FL, intratumoral Tregs are present in significant numbers in biopsy specimens, and markedly inhibit the proliferation and cytokine or granule production of intratumoral CD4 and CD8 T cells [12,13]. The key cytokine originally identified as a T-cell growth factor is interleukin-2 (IL-2) [14]. IL-2 is essential in the development of Tregs, and in the absence of IL-2, Tregs cannot survive or expand in the thymus or in the peripheral blood. Furthermore, IL-2 is directly required for Treg function, and in its absence, Tregs fail to suppress T-cell proliferation [15,16]. IL-2 exerts its effect through binding to its receptor on the cell surface. IL-2 receptor (IL-2R) is composed of three different subunits: α, β and γ. In addition to membrane receptors, several studies have demonstrated the existence of a truncated, soluble form of IL-2Rα that is generated exclusively by the proteolytic cleavage of membrane IL-2Rα [17]. It has been found that the levels of soluble IL-2Rα (sIL-2Rα) are elevated in serum from patients with a variety of cancers, and the levels of sIL2Rα in serum have proven to be useful markers of disease activity [18]. So far, only one study has been performed in patients with FL to establish the role of soluble IL-2Rα. Zhi-Zhang Yang and colleagues performed a comprehensive study, and found that sIL-2Rα facilitates IL-2 signaling and induces Foxp3 expression in T cells, and that sIL-2Rα synergizes with IL-2 to suppress antitumor immunity by suppressing the proliferation and granule production by intratumoral effector T cells [19]. These results indicate that sIL-2Rα plays an active biological role in FL by binding IL-2 and promoting IL-2 signaling rather than depleting IL-2 and blocking its function. When testing 33 previously untreated patients with FL who received rituximab monotherapy, sIL-2Rα serum levels independently predicted progression-free survival (p 0.006). The prognostic impact of sIL2-Rα in a large cohort of patients with FL treated with chemotherapy has not yet been established. This study analyzed the prognostic significance of sIL-2Rα levels in 100 prospectively enrolled patients with previously untreated FL.
Materials and methods Patient study group A total of 100 prospectively enrolled patients with FL with lymphoma grades I–IIIa treated at the Department of
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Table I. Correlation between sIL-2Rα levels and clinical features of 100 patients with follicular lymphoma. Characteristic Age (years) 60 60 Gender Male Female Clinical stage Limited (I/II) Advanced (III/IV) Systemic symptoms Present Absent Tumor bulk 7 cm Present Absent LDH level Below the limit Above the limit Hb level 120 g/L 120 g/L Bone marrow Involved Not involved B2M level 3 mg/L 3 mg/L FLIPI score Low Intermediate High FLIPI-2 score Low Intermediate High
sIL-2Rα 115 pmol/L
sIL-2Rα 115 pmol/L
16 29
17 38
0.62
13 32
17 38
0.83
19 26
6 49
0.001
13 32
20 35
0.15
11 33
38 15
0.001
31 14
32 23
0.27
5 40
11 44
0.23
14 31
39 16
0.001
35 10
20 34
0.001
24 12 9
6 18 31
0.001
31 8 6
10 13 32
0.001
p-Value
sIL-2Rα, soluble interleukin-2 receptor α; LDH, lactate dehydrogenase; Hb, hemoglobin; B2M, β2-microglobulin; FLIPI, Follicular Lymphoma International Prognostic Index.
Hemato-Oncology, University Hospital Olomouc between November 1998 and March 2010 were analyzed. In all patients, the diagnosis of NHL was based on readings of biopsy specimens and confirmed by a university center hematopathologist according to the World Health Organization (WHO) “classification of tumours of haematopoietic and lymphoid tissues.” This study was approved by the institutional independent ethics committee and performed in accordance with the Declaration of Helsinki. Tables I and II show baseline clinical characteristics.
Table II. Clinical features of 55 patients with follicular lymphoma treated with CHOP rituximab therapy. n 55 (100%) Age (median, range) Age 60 years Advanced clinical stage (III/IV) Systemic symptoms (present) Tumor bulk 6 cm Bone marrow involvement B2M level UNL sIL-2Rα 115 pmol/L FLIPI-2 score: low/intermediate/high
59 years (34–79) 23 (42%) 41 (75%) 21 (38%) 24 (44%) 22 (40%) 33 (60%) 25 (45%) 10 (18%)/24 (44%)/21 (38%)
CHOP, cyclophosphamide, doxorubicin, vincristine, prednisone; B2M, β2-microglobulin; sIL-2Rα, soluble interleukin-2 receptor α; FLIPI-2, Follicular Lymphoma International Prognostic Index-2.
1586 V. Procházka et al. 34 (38%) of the chemotherapy-treated patients. Twentynine of them received R (375 mg/m2 every 3 months for 24 months), five patients were treated with interferon α (3 106 IU three times per week for 24 months). Five patients received consolidation with ibritumomab tiuxetan (in three of them followed by R maintenance).
Chemotherapy protocols Figure 1. Scheme of the treatment arms.
Laboratory analyses Laboratory analyses were carried out using fresh blood samples collected on the day of diagnosis. The serum concentration of IL-2Rα was quantified with an enzyme-linked immunosorbent assay (ELISA) using the sIL-2Rα Immunotech Kit (Immunotech, Marseilles, France) and a SpectraCount (Packard BioInstruments, USA) reader with a measuring range of 5–400 pmol/L. A cut-off was set at a value of 115 pmol/L (sensitivity 0.683, 1 specificity 0.475) as identified using receiver operating characteristic (ROC) analysis. Area under the ROC curve (AUC) was 0.604 with standard error 0.057. The asymptotic significance of the AUC reached 0.078 (asymptotic 95% confidence interval [CI] 0.493–0.715).
Treatment Eleven patients (11%) did not fulfill the GELF (Groupe d’Etude des Lymphomes Folliculaires) criteria for systemic treatment initiation [20]. These patients – all with a limited disease stage – were observed (watch and wait policy, n 6) or treated with local involved-field radiotherapy (n 5). Eighty-nine patients (89%) were treated with chemotherapy (Figure 1). Fifty-two patients (58.4%) were able to receive therapy with lymphoma risk-appropriate intensity, whereas 37 patients (41.6%) were treated irrespective of the disease risk (standard cyclophosphamide, doxorubicin, vincristine, prednisone [CHOP] or CHOP-like therapy in 32 and sequential chemotherapy in five of the patients). Front-line treatment of the 52 suitable patients was stratified according to the commonly used risk factors (FLIPI, β2-microglobulin [B2M] and serum thymidine kinase levels, bulky disease) and with regard to age and comorbidities into three treatment groups (Table III). Rituximab was added to front-line chemotherapy in 66 (74%) of the chemotherapy-treated patients. Maintenance treatment after front-line therapy was indicated in
CHOP and ProMACE-CytaBOM (prednisone, doxorubicin, cyclophosphamide, etoposide, cytarabine, bleomycin, vincristine, methotrexate, leucovorin) protocols were administered as previously published [21,22]. The sequential chemotherapy protocol consisted of three cycles of a CHOEP21-like regimen (PACEBO), one cycle of an ifosfamide and methotrexate-based regimen (IVAM) and a priming regimen with high-dose cytosine arabinoside (HAM). The PACEBO regimen was administered as follows: doxorubicin 40 mg/m2 intravenously (IV), day 1; cyclophosphamide 850 mg/m2 IV, day 1; etoposide 200 mg/m2 IV, day 1; bleomycin 10 mg/m2 IV, day 8; vincristine 1.4 mg/m2 (maximum 2.0 mg) IV, day 8; and prednisone 40 mg/m2 orally, days 1–14. The IVAM regimen consisted of ifosfamide 1500 mg/m2 IV, days 1–5; etoposide 150 mg/m2 IV, days 1–3; cytosine arabinoside 100 mg/m2 IV, days 1–3; methotrexate 3 g/m2 IV, day 5; mesna prophylaxis 1200 mg IV, days 1–5; and leucovorin rescue 25 mg/m2 IV, from day 6/7 until the plasma methotrexate level was below 0.05 μmol/L. The HAM regimen was administered as follows: cytosine arabinoside 2 g/m2 twice daily IV, days 1 and 2; mitoxantrone 10 mg/m2, days 2 and 3 [23]. Stem cell mobilization was performed with 12 μg/kg of filgrastim given subcutaneously twice daily. The BEAM (BCNU, etoposide, cytarabine, melphalan) 200 conditioning regimen dosage was standard, as previously published [24].
Treatment response The treatment responses, classified as follows: complete response (CR), unconfirmed complete response (CRu), partial response (PR), stable disease (SD) and progressive disease (PD), were defined according to the International Workshop NHL Response Criteria published by Cheson et al. [25].
Statistical analysis The optimal cut-off point of the sIL-2Rα was identified with ROC analysis. The OS was defined as the time from diagnosis to the date of the last follow-up examination (censored) or the date of death (event) from any cause. The PFS was
Table III. Risk-adapted treatment stratification strategy (n 52). Risk group Low risk (n 23) Intermediate risk (n 8) High risk (n 21)
FLIPI FLIPI 0 FLIPI 1 FLIPI 1 FLIPI 2 FLIPI 3–5
Number of present additional risk factors 0–3 1–2 3 0–3 0–3
Treatment arm CHOP Sequential chemotherapy Sequential chemotherapy plus autologous stem cell transplant (BEAM)*
Rituximab added to induction 16 (69.6%) 8 (100%) 15 (71.4%)
FLIPI, Follicular Lymphoma International Prognostic Index; CHOP, cyclophosphamide, doxorubicin, vincristine, prednisone; BEAM, BCNU, etoposide, cytarabine, melphalan. *One patient received ProMACE-CytaBOM induction regimen instead of sequential chemotherapy due to historical reasons.
IL-2 receptor in follicular lymphoma
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defined as the date from first treatment to the date of documented disease progression or death from any cause (event) or the date of the last follow-up examination (censored). The Kaplan–Meier method was used to estimate the survival curves. The log-rank test was used to compare differences in survival times between patient subgroups. The relationship between sIL-2Rα levels (normal or elevated) and the standard prognostic factors were analyzed using the χ2 or Mann–Whitney U-test for qualitative or quantitative variables, respectively. A Cox proportional hazards model was used to assess the effects of the prognostic factors on OS or PFS. Both univariate and multivariate models were fitted. All significance levels were set to 0.05.
Results Analysis of treatment response and survival Treatment response was assessable in all 94 (100%) treated patients. CR or CRu was achieved in 78 (83.0%), PR in 13 (13.8%) and SD or PD in three (3.2%) of the patients. Patients with sIL-2Rα levels above 115 pmol/L had a lower, but not statistically significant, probability of CR achievement than patients with sIL-2Rα levels below the limit (78.2% vs. 86.8%, p 0.29). During the observation period, lymphoma relapsed in 36 patients (median time to relapse 26.2 months; range, 6.3–94.3 months) and 24 patients died (four of them in CR). After a median follow-up of 79.4 months (range 22–151 months), the OS of all patients reached 81.4% (95% CI 0.74–0.89) at 5 years. The PFS at 5 years reached 60.4% (95% CI 0.50–0.70); median time to progression was not reached. The 5-year PFS of patients with elevated sIL-2Rα level was 49.7% (95% CI 0.36–0.63), as compared to 70.9% (95% CI 0.57–0.85, p 0.03) in patients with sIL-2Rα below the limit (Figure 2). The 5-year OS of all patients with elevated sIL-2Rα levels was 74.0% (95% CI 0.62–0.86), as compared to 91.0% in patients with sIL-2Rα below the limit (95% CI 0.82–0.99, p 0.062) (Figure 3). Subanalysis of the 55 patients treated with CHOP or CHOP-like regimens showed superior 5-year PFS in patients
Figure 3. Overall survival curves, all patients. Patients with sIL-2Rα 115 pmol/L (black line), patients with sIL-2Rα 115 pmol/L (gray line), p 0.062.
with sIL-2Rα 115 pmol/L (68.6%, 95% CI 0.51–0.86) compared to those with sIL-2Rα 115 pmol/L (37.5%, 95% CI 0.18–0.57, p 0.01) (Table IV). Patients with lower sIL-2α levels also had much better OS at 5 years: 90.0% (95% CI 0.79–1.00) vs. 53.8% (95% CI 0.33–0.74, p 0.02). Rituximab (R) was added to CHOP equally in both groups: in 67% of cases in the low sIL-2Rα group and in 72% in the high sIL-Rα group (p 0.67). When focusing on the R-CHOP arm only (n 38), sIL-2Rα was still highly predictive for both PFS and OS. Five-year PFS in the low sIL-2Rα group was 84.4% (95% CI 0.68–1.00) compared to only 37.0% (95% CI 0.14–0.60, p 0.002) in the high sIL-2Rα group (Figure 4). Five-year OS in the low sIL-2Rα group reached 95.0% (95% CI 0.85–1.00), in contrast with only 38.9% (95% CI 0.13–0.64, p 0.0004) in patients with high sIL-2Rα levels (Figure 5, Table IV). On the other hand, patients with high-risk FL treated with more intensive protocols with (n 21) or without (n 13) autologous stem cell transplant consolidation did not have a different outcome regarding sIL-2Rα levels. No difference was seen in terms of OS (p 0.36) or PFS (p 0.98, data not shown).
Univariate and multivariate analyses
Figure 2. Progression-free survival curves, all patients. Patients with sIL-2Rα 115 pmol/L (black line), patients with sIL-2Rα 115 pmol/L (gray line), p 0.03.
We have shown that sIL-2Rα levels stratify patients well with respect to OS and PFS, both in the whole population and in the subgroup treated with CHOP-like regimens. There is a natural question regarding how good a predictor sIL-2Rα is with respect to the traditional predictors composing the FLIPI-2 index. To this end, we performed both univariate and multivariate Cox regression models. The FLIPI-2 index incorporates five dichotomic predictors: age over 60 years, bulky disease ( 6 cm), involvement of bone marrow, hemoglobin level less than 120 g/L and elevated B2M. The presence of any of these five factors adds one point to the FLIPI-2 index. Patients are stratified into three groups: low risk (FLIPI-2 0 points), intermediate risk (FLIPI-2 1–2 points) and high risk (FLIPI-2 3 points). We first assessed the predictive power of the FLIPI-2 variables. In the whole population (n 100), only B2M (out of the five FLIPI-2 predictors) proved to be a significant
1588 V. Procházka et al. Table IV. Survival of patients stratified according to sIL-2Rα level. All patients sIL-2Rα 115 sIL-2Rα 115 CHOP rituximab (n 55) sIL-2Rα 115 sIL-2Rα 115 R-CHOP (n 38) sIL-2Rα 115 sIL-2Rα 115
5-year OS
95% CI for OS
5-year PFS
95% CI for PFS
p-Value
81.4% 74.0% 91.0%
0.74–0.89 0.62–0.86 0.82–0.99
p-Value — 0.062
60.4% 49.7% 70.9%
0.50–0.70 0.36–0.63 0.57–0.85
— 0.03
53.8% 90.0%
0.33–0.74 0.79–1.00
0.02
37.5% 68.6%
0.18–0.57 0.51–0.86
0.01
38.9% 95.0%
0.13–0.64 0.85–1.00
0.001
37.0% 84.4%
0.14–0.60 0.68–1.00
0.002
sIL-2Rα, soluble interleukin-2 receptor α; CHOP, cyclophosphamide, doxorubicin, vincristine, prednisone; R-CHOP, rituximab-CHOP; OS, overall survival; CI, confidence interval; PFS, progression-free survival.
univariate predictor (p 0.007, hazard ratio [HR] 2.8) of PFS (Table V). The other four predictors were not significant. However, when the FLIPI-2 index (three-valued) was taken as the only predictor in the Cox proportional hazards model, the predictor was significant (p 0.0028), yielding an HR of 2.22 between the adjacent risk groups. Thus, the FLIPI-2 index retained the predictive power of the B2M predictor. The sIL-2Rα level as the only predictor of PFS yielded an HR of 2.02 (p 0.037), which is comparable to the predictive power of B2M (and thus also FLIPI-2). If we attempted to construct a multivariate Cox proportional hazards model, with a combination of any of the FLIPI-2 variables and the sIL-2Rα level as predictors, none of the predictors remained significant. The same type of analysis for the OS of the whole group (n 100) revealed that age (p 0.0061, HR 3.12) and B2M (p 0.0048, HR 8.03) were the only two significant univariate FLIPI-2 predictors of OS (Table VI). The high predictive power of B2M translated into the FLIPI-2 index. If the index was used as the only univariate predictor, it yielded an HR 3.75 (p 0.0021). In the case of OS, the sIL-2Rα level was not a significant univariate predictor (p 0.071). Multivariate analysis did not bring any new information. Turning to the subgroup of 54 patients who were treated with the CHOP regimen, in the case of PFS, the sIL-2Rα level proved to be the best univariate predictor (HR 2.68, p 0.015). Out of the five FLIPI-2 predictors, only the following two were significant: B2M (HR 2.45, p 0.043)
Figure 4. Progression-free survival curves of 55 patients treated with CHOP rituximab chemotherapy. Patients with sIL-2Rα 115 pmol/L (black line), patients with sIL-2Rα 115 pmol/L (gray line), p 0.002.
and bulk (HR 1.91, p 0.010). The FLIPI-2 index proved to be a significant univariate predictor (p 0.0073 and HR 2.30 between adjacent risk groups). Multivariate analysis did not bring any new information in this case. In the case of OS, we noted the high predictive power of B2M (HR 14.99, p 0.0088). Also bulk (HR 2.72, p 0.048) and age (HR 2.66, p 0.051) provided some predictive power, in the category of univariate FLIPI-2 predictors. The FLIPI-2 index yielded an HR 4.24 (p 0.0025) between the adjacent risk groups. The sIL-2Rα level was a significant univariate predictor (HR 3.33, p 0.027); however, its power was overshadowed by B2M. Multivariate analysis did not bring any new information in this case.
Discussion Our study is the first analysis of pretreatment serum IL-2Rα levels in a large FL population treated with chemotherapy R. We found serum IL-2Rα levels to be a significant predictor of PFS and with borderline significance also for OS in the whole population. The predictive power of sIL-2Rα strongly depends on the intensity of front-line chemotherapy. When testing patients treated with CHOP or CHOP-like regimens with or without R, sIL2Rα was found to be the best univariate predictor for PFS. Patients with sIL-2Rα 115 pmol/L showed almost double 5-year PFS (68.6%) compared to those with sIL-2α 115 pmol/L (37.5%). PFS advantage was translated into overall
Figure 5. Overall survival curves of 55 patients treated with CHOP rituximab chemotherapy. Patients with sIL-2Rα 115 pmol/L (black line), patients with sIL-2Rα 115 pmol/L (gray line), p 0.0004.
IL-2 receptor in follicular lymphoma Table V. Univariate models for progression-free survival, all patients (n 100). Variable Age (above 60) Bulk ( 6 cm) Bone marrow involvement Hemoglobin level ( 120 g/L) B2M level ( UNL)* sIL-2R level ( 115 pmol/L) FLIPI-2 (L vs. I vs. H)
Exp(B)
p-Value
95% CI
1.74 1.52 1.45 1.44 2.77 2.01 2.22
0.081 0.191 0.247 0.361 0.007 0.037 0.003
0.93–3.24 0.81–2.85 0.77–2.72 0.66–3.13 1.32–5.81 1.05–3.90 1.32–3.75
B2M, β2-microglobulin; sIL-2R, soluble interleukin-2 receptor; FLIPI-2, Follicular Lymphoma International Prognostic Index-2; L, low; I, intermediate; H, high; CI, confidence interval. *Upper normal limit 2.4 mg/L.
survival: OS at 5 years was 90.0% in the low sIL-2Rα group as compared to 53.8% in the high sIL-2Rα group. This survival advantage was retained even when analyzing the R-CHOP population. Patients with low sIL-2Rα level had overwhelmingly superior 5-year PFS (84.4% vs. 37.0%) and also 5-year OS (95.0% vs. 38.9%). On the other hand, when analyzing patients treated with more intensive treatment strategies including high-dose therapy and autologous stem cell transplant, the sIL-2Rα levels showed no prognostic role. The role of some conventional prognostic factors implemented into the FLIPI-2 score was only limited. Apart from age above 60 and B2M levels, none of the FLIPI-2 related parameters were found to be significant predictors in either univariate or multivariate analyses. When analyzing only patients treated with CHOP R, we found also a predictive power of bulk (PFS). In the context of FLIPI-2 factors sIL-2Rα level was found to be a predictor of OS and PFS irrespective of the population studied. Moreover, the sIL-2Rα level correlated strongly with well-known unfavorable parameters such as bulky disease, bone marrow involvement and B2M levels [26]. The prognostic value of serum sIL-2Rα assessment was confirmed in several clinical trials in the R era, but data are restricted to patients with diffuse large B-cell lymphoma treated with R-CHOP only. First, Goto and co-workers analyzed pretreatment levels of sIL-2Rα in 233 patients. With a cut-off level of 2000 U/mL, they found sIL-2Rα to be a predictor for both OS and PFS independent of IPI factors [27]. Second, Yamauchi and colleagues analyzed sIL-2Rα obtained after chemotherapy in 21 patients with diffuse large B-cell lymphoma (DLBCL) treated with R-CHOP therapy. They found elevated sIL-2Rα level to be a strong predictor for early disease relapse [28]. Similar
1589
results were obtained in a large retrospective study conducted by Ennishi and colleagues. They retrospectively analyzed 141 R-CHOP-treated patients. Those with low sIL-2Rα level (below median) had a much better 2-year event-free (92% vs. 66%, p 0.001) and also 2-year OS (95% vs. 82%, p 0.005) [29]. Third, Tomita and co-workers analyzed a novel prognostic index composed of three independent factors: sIL-2Rα (cutoff 2500 U/mL), clinical stage and LDH level (SIL). Their SIL index was tested in patients with DLBCL and was able to stratify patients into standard risk (5-year OS 91%) and high risk (5-year OS 67%) groups [30]. Very recently, the first article focusing on sIL-2R relevance in patients with FL was published. Yoshizato et al. found the sIL-2Rα level to be a predictor for PFS and time to next treatment. Unfortunately, the study group was rather small (n 54) and the follow-up short (up to 4 years) [31]. Although both the above studies and our data confirm the possible prognostic role of sIL-2Rα, uncertainty regarding the utility of sIL-2Rα in lymphoma still remains. First, there are many different laboratory techniques of sIL-2Rα measurement with different cut-off values. Second, prognostic power was confirmed only in patients treated with the R-CHOP regimen; different or more intensive regimens have not yet been tested. Finally, soluble IL-2Rα plays an important biological role in tumor immunosurveillance. This fact reflects the presence of advanced disease features such as bulky disease, high B2M and higher FLIPI/FLIPI-2 scores. A high level of sIL-2Rα should be considered a negative prognostic factor, complementary to the modern FLIPI-2, especially in patients treated with CHOP-like regimens in the R era.
Acknowledgements This study was supported by student project LF-2013-004 of the Faculty of Medicine and Dentistry, Palacky University, Olomouc. We would like to thank Mrs Kateˇrina Sicˇová and Mrs Lenka Prokopová for technical support, Mr. Pavel Kurfürst for English proofreading and Dr. Tomáš Fürst for statistical analyses.
Potential conflict of interest: Disclosure forms provided by the authors are available with the full text of this article at www.informahealthcare.com/lal.
Table VI. Univariate models for overall survival, all patients (n 100). Variable Age (above 60) Bulk ( 6 cm) Bone marrow involvement Hemoglobin level ( 120 g/L) B2M level ( UNL)* SIL-2R level ( 115 pmol/L) FLIPI-2 (L vs. I vs. H)
Exp(B)
p-Value
95% CI
3.12 1.83 1.36 2.34 8.03 2.36 3.75
0.006 0.164 0.468 0.063 0.005 0.071 0.002
1.38–7.05 0.78–4.28 0.59–3.15 0.96–5.74 1.89–34.2 0.93–6.00 1.61–8.74
B2M, β2-microglobulin; sIL-2R, soluble interleukin-2 receptor; FLIPI-2, Follicular Lymphoma International Prognostic Index-2; L, low; I, intermediate; H, high; CI, confidence interval. *Upper normal limit 2.4 mg/L.
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