Acute Lymphoblastic Leukemia |
1 Servei dHematologia Clínica, Institut Català dOncologia, Hospital Germans Trias i Pujol, Badalona, Spain
2 Hospital Clínico Universitario, Salamanca
3 Hospital Clínico Universitario, Valencia
4 Hospital Morales Meseguer, Murcia
5 Hospital General, Alicante
6 Hospital Universitario Carlos Haya, Málaga
7 Hospital La Fe, Valencia
8 Hospital de la Vall dHebron, Barcelona
9 Hospital Doce de Octubre, Madrid
10 Hospital Clínico San Carlos, Madrid
11 Hospital Josep Trueta, Girona
12 Hospital de Sant Pau, Barcelona
13 Hospital San Pedro de Alcántara, Cáceres
14 Hospital Central de Asturias, Oviedo
15 Hospital Virgen de la Victoria, Málaga
16 Hospital Miguel Servet, Zaragoza and
17 Hospital Materno-Infantil de la Vall dHebron, Barcelona, Spain
Correspondence: Albert Oriol, Servei dHematologia Clínica, Institut Català dOncologia, Hospital Germans Trias i Pujol, Ctra. Del Canyet s/n 08916 Badalona, Barcelona, Spain. E-mail: aoriol{at}iconcologia.net
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Design and Methods: We analyzed the characteristics, the outcome and the prognostic factors for survival after first relapse in a series of 263 adult patients with acute lymphoblastic leukemia (excluding those with mature B-cell acute lymphoblastic leukemia) prospectively enrolled in four consecutive risk-adapted PETHEMA trials.
Results: The median overall survival after relapse was 4.5 months (95% CI, 4–5 months) with a 5-year overall survival of 10% (95% CI, 8%–12%); 45% of patients receiving intensive second-line treatment achieved a second complete remission and 22% (95% CI, 14%–30%) of them remained disease free at 5 years. Factors predicting a good outcome after rescue therapy were age less than 30 years (2-year overall survival of 21% versus 10% for those over 30 years old; P<0.022) and a first remission lasting more than 2 years (2-year overall survival of 36% versus 17% among those with a shorter first remission; P<0.001). Patients under 30 years old whose first complete remission lasted longer than 2 years had a 5-year overall survival of 38% (95% CI, 23%–53%) and a 5-year disease-free survival of 53% (95% CI, 34%–72%).
Conclusions: The prognosis of adult patients with acute lymphoblastic leukemia who relapse is poor. Those aged less than 30 years with a first complete remission lasting longer than 2 years have reasonable possibilities of becoming long-term survivors while patients over this age or those who relapse early cannot be successfully rescued using the therapies currently available.
Key words: acute lymphoblastic leukemia, relapse, rescue treatment, prognostic factors.
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Table 1. Backbone treatment of the PETHEMA ALL8913, ALL93HR,14 ALL96IR15,16 and ALL03HR17 trials.
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Statistical analysis
Homogeneity of outcome across initial treatments was analyzed after stratifying the patients according to initial risk (standard versus high) and age (15–30, 30–55 and 55–70 years) using the
2 and log-rank tests.18 Disease-free survival was defined as the time from second remission to last control, subsequent relapse or death; overall survival was defined as the time from first relapse to last control or death. The variables tested for prognostic significance after relapse included patient-related data (age, gender), leukemia-related factors (WBC count, phenotype and cytogenetics), relapse-related factors (duration of first complete remission and site of relapse) and treatment. Differences in relative risks of death during reinduction or achievement of second complete remission were assessed using the
2 test. Kaplan-Meier curves19 and log-rank statistics were used for comparisons of disease-free survival and overall survival. Significant variables in univariate studies for second remission, disease-free survival and overall survival were included in multivariate logistic or Cox regression models. 20 Statistical analyses were performed using a SPSS package v15.0 (Chicago, IL, USA).
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Patients characteristics at relapse
The median age of relapsed patients was 33 years (range, 15–69) and 150 (57%) were male. Relapses occurred during early consolidation in 46 patients (17%), after high-dose therapy and SCT in 71 (28 autologous - 10%, 43 allogeneic -16%) and during late consolidation, maintenance or beyond in 146 (55%). Most relapses occurred in the bone marrow either as the sole documented site (226 cases, 86%) or combined with central nervous system, testes or other locations (n=19, 7%). Exclusive extramedullary relapses occurred in the central nervous system (n=15); skin/soft tissue (n=2) and testes (n=1). Among patients with high-risk features at diagnosis, 41 (15%) carried high-risk translocations including 27 with t(9;22), 3 with t(1;19) and 11 with t(4;11).
Outcome after relapse
The median survival after relapse was 4.5 months (95% CI, 4–5 months). The 1-year overall survival was 24% (95% CI, 20–26%), and the 5-year overall survival was 10% (95% CI, 8–12%). In 15 patients (6%) no treatment was attempted to obtain a second remission. The median age of this subgroup of patients was 58 years (range, 43 to 69) and their median survival was 1 month (range, 0–2.3). SCT was attempted without re-induction therapy in 11 patients (4%) with a generally poor outcome. These cases included SCT without prior re-induction in two patients with incipient relapse (2 failures) and direct donor lymphocyte infusion in six patients submitted to allogeneic SCT (failure to achieve second remission, 1; non-relapse mortality, 3; subsequent relapse, 2). However, a durable second remission was obtained in two out of three patients with isolated central nervous system relapse conditioned with total body irradiation and receiving intrathecal therapy without systemic re-induction. An allogeneic SCT was attempted in two patients with active disease after re-induction failure and a durable second remission was obtained in one of them. Conventional re-induction treatment was given to 237 (90%) patients, and included regimens similar to first-line induction in 97 patients (37%), HyperCVAD6 or similar regimens in 83 (32%) and fludarabin-idarubicin (FlagIda)-based treatments in 26 (10%), whereas other regimens were administered to the remaining 31 patients. Death during induction occurred in 44 patients (17%) and second remission was achieved in 112 out of 248 patients (45%) receiving intensive second line treatment. The median disease-free survival after second remission was 6 months (95% CI, 5–7). The 1-year disease-free survival probability was 34% (95%CI, 26–42%) while the 5-year disease-free survival probability was 22% (95% CI, 14–30%). Thirty-three patients (30%) achieving second remission were not submitted to SCT (2 remain alive after standard consolidation, 30 relapsed before SCT and 1 died after further consolidation treatment in second remission), 14 (12%) received an autologous SCT (6 alive, 4 relapsed, 4 died of transplant-related events), 38 received a matched sibling allogeneic SCT (7 alive, 16 relapsed, 14 died of transplant-related events and 1 died of a second neoplasia) and 27 (24%) received an unrelated allogeneic SCT (14 alive, 8 relapsed, 5 died of transplant-related events). In all, 28 out of 113 relapsed patients who achieved a second remission (25%) remain alive without further relapse after a median follow-up of 6 years (range, 2–17).
Prognostic factors for achievement of second remission and survival after relapse
Table 2 summarizes the univariate analysis of factors predictive for re-induction-related death, second remission attainment, disease-free survival and overall survival. Baseline leukocytosis and gender were associated with a shorter overall survival. Females showed a higher rate of death during re-induction; however, the probability of achieving a second remission and disease-free survival were not significantly different between sexes. An analysis restricted to patients receiving active treatment showed that patients over 55 years had a lower second remission rate than those under this age (47% versus 20%, P=0.015). The median overall survival was 6.8 months (95% CI, 4.9–8.6) for patients up to 30 years compared to 4.2 months (95% CI, 3.7–4.8) for patients 30–55 years old (P=0.011) and 3.2 months (CI 95%, 2.4–4) for those over 55 years (P= 0.022) (Figure 1A). Disease-free survival was also significantly longer for younger patients (Figure 1B). Four patients over 55 years old achieved a second remission and none was subsequently submitted to any form of SCT. Only one of them remains alive and free of disease after achieving a second remission. Although phenotype did not have a significant influence on outcome after relapse, heterogeneity among small subsets of patients in each group could not be excluded (e.g. failure to respond in 4/4 mature thymic ALL). The complete remission rate of patients with normal cytogenetics (45%) was comparable to that of patients with t(9;22) (48%) or miscellaneous abnormalities (37%). However, only one out of three patients with t(1;19) and two out of 11 with t(4;11) achieved a second remission and none of these responses was durable. Similarly, the median disease-free survival of relapsed patients with t(9;22) was 4 months with only two out of 27 patients still alive and in second remission at the last control.
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Table 2. Univariate analysis of prognostic factors for reinduction death, second complete remission attainment, disease-free survival and overall survival after relapse in the 248 patients treated intensively after first relapse.
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Figure 1. Probabilities of overall survival and disease free survival from first relapse of 248 adult patients with ALL who received rescue treatment according to age at diagnosis (A and B) and time from diagnosis to relapse (C and D).
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The probabilities of successful treatment after relapse were not affected by SCT procedures during first complete remission among the 209 patients (84%) who relapsed late enough to receive late consolidation in first complete remission with conventional chemotherapy (67%), allogeneic SCT (20%) or autologous SCT (13%). Although those patients submitted to SCT in first complete remission tended to have a lower second remission rate (36% versus 49%, P=0.07) and a lower 5-year overall survival probability, 5% (95%CI, 0%–10%) versus 17% (95%CI, 11%–23%) (P=0.004), the differences lost statistical significance after adjustment for age and risk. Transplant-related mortality was higher for patients already submitted to a SCT in first complete remission (23% versus 45%, P=0.06). Patients treated upon relapse with FlagIda-like re-induction therapy had a higher rate of achievement of second remission although the difference was not statistically significant after adjustment for age.
The results of multivariate analysis are summarized in Table 3. Age and duration of first complete remission were the two independent prognostic factors for response and survival. Female gender retained prognostic significance for a higher probability of death during salvage induction therapy. The subgroup of patients under 30 years old and with a first complete remission lasting over 2 years (representing 13% of the whole cohort) had an 5-year overall survival of 38% (95% CI, 23–53%) and a 5-year disease-free survival of 53% (95% CI, 34–72%) (Figure 2).
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Table 3. Multivariate analysis for factors associated with death during rescue induction, second complete remission achievement, overall survival and disease-free survival in patients with relapsed ALL receiving intensive treatment.
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Figure 2 Comparison of the overall survival (A) and disease-free survival (B) from first relapse of patients with ALL up to 30 years of age and with a first remission lasting more than 2 years (N=34) versus all other patients who received intensive treatment (N=214).
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The PETHEMA trials have used a common backbone of treatment for adult patients with newly diagnosed ALL for more than a decade allowing the analysis of a cohort with mature follow-up. However, several drawbacks must be taken into account. First, as in other large cohorts,10,11,21 the use of risk-adapted initial therapy precluded the possibility of exploring the prognostic implications of initial treatment strategies. Secondly, as in the aforementioned studies, the rescue strategy was not uniform. Re-induction treatments have only been explored prospectively in short series.9 However, some type of allogeneic SCT after achievement of second remission is considered necessary. 21 Finally, analysis of specific cytogenetic subgroups was limited, given that some important cytogenetic abnormalities are infrequent. In the case of t(9;22), the emergence of novel specific therapies,22–26 which were available at relapse for some of the patients in the cohort, may have had an influence on rescue strategies.
The design of our study, based on a full-cohort followup, has provided other relevant data. Prior studies10,11 did not address the proportion of patients following alternative options of rescue treatment and their outcome or those receiving palliative treatment only. Donor lymphocyte infusion or other SCT strategies without prior chemotherapy had poor results, although the data were based on small numbers of patients. The proportion of untreated patients was relatively small (6%) and these patients were mostly elderly. In fact, the feasibility of standard rescue treatment was only anecdotal in patients over 55 years, with less than a quarter achieving second remission and with subsequent relapse occurring in most. Age has consistently been associated with a dismal prognosis in most studies.10,11.20 Although rescue treatment was attempted in most patients aged 30–55 years old, the study shows that these patients outcome was as poor as that of the older patients. Thus, patients over 30 years of age form a uniform group likely to benefit from being enrolled into clinical trials with novel drugs.
Another large cohort study described female sex as a predictor of poor outcome in adult ALL after relapse,11 a factor that had not been identified in previous studies.8–10 We found female sex to be specifically associated with a high rate of death during re-induction. Although the increased early death rate in females had an impact on their overall survival, female patients achieving second remission enjoyed the same disease-free survival as males. This finding might be partially explained by a high proportion of females in the older age groups but gender retained independent prognostic significance on multivariate analysis along with age. We also excluded the possibility of interactions with other variables such as less intensive treatment, different rates of failure to undergo allogeneic SCT or a higher incidence of poor-risk initial ALL characteristics among females. Although there is not a clear explanation for this finding, its appearance in the analysis of two large independent cohorts makes the possibility of a hazard effect unlikely.
As in prior studies,11 we failed to identify any statistically significant association between the initial characteristics of ALL and prognosis after relapse. High initial WBC counts lost statistical significance when included in the multivariate model. However, some associations cannot be completely excluded. No patient with mature thymic ALL could be rescued after relapse in our series. The prognostic significance of cytogenetics could also have been biased by the small numbers of patients analyzed as no patient with t(1;19) or t(4;11) obtained sustained second remission. Regarding t(9;22), despite having an identical second remission rate to patients with standard-risk cytogenetics (48%), second remissions lasted less than 1 year in more than half of these patients mainly due to relapse. Only two patients with t(9;22) ALL remained alive and in second remission at the last control. Our study failed to confirm the results of a previous report11 attributing a worse prognosis to patients relapsing in the central nervous system.
On the other hand, the dismal prognosis of early relapsers was clearly confirmed. An important proportion of the desperate attempts to achieve second remission in younger patients relapsing during consolidation or early afterwards may be related to the absence of available investigational alternatives until recent times. Currently, early relapsers of any age, along with patients over 30 years old, should be strongly encouraged to participate in clinical trials with newly available experimental agents.
The optimal first-line strategy in adult ALL is under debate, with evidence in favor of both pursuing an allogeneic SCT in first remission7 and of reserving SCT procedures for very high-risk patients.14,16,27,28 The role of initial therapy in determining outcome after relapse has been controversial.8,11 Patients from the ALL89, ALL96SR and ALL03HR trials received an allogeneic SCT only if slow response to treatment was observed, thus patients with adverse prognostic features were selected for SCT. The detrimental effect of a prior SCT in first complete remission in our series lost prognostic significance when age and risk factors were considered. When patients submitted to some type of SCT were matched with comparable patients and particularly when analysis was restricted to patients randomized between chemotherapy and maintenance, allogeneic SCT or autologous SCT (trial ALL93HR), no differences in outcome were observed, with roughly half of the patients achieving second remission and three quarters of them being able to undergo a SCT procedure. Within the select subset of patients undergoing a high-dose procedure, the proportions of patients who experienced transplant- related mortality, who relapsed or who maintained a durable second remission were about one third each, regardless of prior allogeneic or autologous SCT procedures in first complete remission. Thus, our study proves that first complete remission consolidation strategies are unlikely to hamper the possibility of a successful allogeneic SCT after relapse. Differences in efficacy among rescue treatments were largely affected by age, center effects and time to transplant. The best re-induction strategy remains to be determined. Our results confirm that any effective induction followed by prompt allogeneic SCT may be a judicious strategy. However, only younger patients with late relapses appear to benefit from such an approach. In the subgroup with the best prognosis, autologous SCT or even standard consolidation after second remission may be equally effective when a donor is not available.
In summary, we identified a small but relevant subgroup of adults with ALL in whom the chances of long-term survival may approach those of patients with newly diagnosed ALL. Late relapsers may retain chemosensitivity to previously used agents and have a relatively important second remission rate that allows subsequent high-dose therapy procedures with considerable chances of success. On the other hand, early relapsers and patients unfit to follow high-dose procedures should be included in trials involving novel therapeutic agents.29
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JMR designed and coordinated the original trials; SV collected and verified the data; AO analyzed the data and wrote the paper. All authors participated in data collection and contributed to writing the paper. JMR checked the final version of the manuscript; JMR was study chair of the original trials and the joint final analysis. All other authors participated in the original clinical trials, followed patients clinically, updated information on outcome and reviewed the manuscript critically. No potential conflicts of interests relevant to this article were reported.
Received for publication July 13, 2009. Revision received September 12, 2009. Accepted for publication September 14, 2009.
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