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Acute Lymphoblastic Leukemia |
From the Division of Hematology, Department of Cellular Biotechnologies and Hematology, University "La Sapienza", Roma (AV, AG, CA, GM, MV, RF); Department of Clinical and Experimental Medicine, University of Verona (OP, GP); Division of Hematology, Ospedale S. Carlo, Potenza (MP); Hematology, Ospedale di Montefiascone (CDG); Hematology, Ospedale A. Cardarelli, Napoli (VM); Hematology, Ospedale E. Morelli, Sondalo (AP); GIMEMA Foundation, Roma, Italy (FM).
Correspondence: Antonella Vitale, MD, Division of Hematology, Department of Cellular Biotechnologies and Hematology, University "La Sapienza", Via Benevento 6, Rome, 00161 Italy E-mail: vitale{at}bce.uniroma1.it
| ABSTRACT |
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Design and Methods: We analyzed the expression of the MyAg CD13 and/or CD33 in a cohort of 377 adult patients with de novo ALL enrolled and treated in the GIMEMA ALL 0496 protocol.
Results: MyAg expression was documented in 35% of the 377 adult ALL cases analyzed. MyAg were significantly more frequently associated with B-lineage ALL (38%) than with T-ALL (24%) (p=0.02). No difference was found with regard to clinical features at presentation; a difference was found only for white cell count (p=0.03), percentage of peripheral blasts (p=0.004) and platelet count (p=0.004). No difference was observed in the expression of MyAg between patients with normal or abnormal cytogenetics or between those with high-risk (BCR-ABL+, ALL1-AF4+, E2A-PBX1+) or low-risk B-lineage ALL. We failed to observe any difference between MyAg-positive and MyAg-negative cases in terms of achievement of complete remission, disease-free survival and overall survival at 5 years.
Interpretation and Conclusions: Our data indicate that ALL MyAg expression in adults with ALL is not associated with adverse presenting clinical and biological features, and that response to treatment and prognosis is comparable in MyAg-positive and MyAg-negative ALL patients with regards to both complete remission rate and overall survival. We suppose that these result are due to more intensive treatment modalities adopted in the GIMEMA ALL 0496 protocol.
Key words: myeloid antigen, adult ALL, prognosis.
Aberrant myeloid antigen (MyAg) expression occurs in 10–40% of adult patients with acute lymphoblastic leukemia (ALL).1–3 The prognostic value of MyAg expression in adult ALL is still controversial; while early studies suggested an inferior outcome for MyAg+ ALL patients,2,4–6 other published series with protocols based on high-dose chemotherapies have failed to confirm a prognostic correlation.3,7,8 Within the multicenter Gruppo Italiano Malattie EMatologiche dellAdulto (GIMEMA) ALL 0496 protocol, a central handling of biological material at presentation was required for all registered cases. Taking advantage of this overall framework, we examined the expression of aberrant MyAg in a large cohort of adult ALL patients uniformly characterized and treated. The aims of our analysis were to determine the incidence of MyAg expression in a group of adult ALL evaluated homogeneously at diagnosis, to investigate the relationships of MyAg expression with other clinical, hematologic and biological characteristics, and to establish the prognostic importance of MyAg expression in terms of response to induction treatment and long-term survival.
| Design and Methods |
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Cytogenetic and molecular investigations
Metaphases from short-term bone marrow cultures were prepared in a single laboratory (Department of Hematology: "La Sapienza", University Rome) according to standard methods and GTG banded chromosomes were classified following the International System for Human Cytogenetic Nomenclature.12 A minimum of ten GTG banded metaphases were required to consider the case evaluable. Three referral laboratories (Departments of Hematology: "La Sapienza", University Rome; University of Ferrara; and University of Perugia) performed the cytogenetic analyses at diagnosis. The GIMEMA cytogenetic committee reviewed all cases. The presence of different fusion transcripts (E2A-PBX1, BCR-ABL, ALL1-AF4, TEL-AML1) was detected by reverse transcriptase polymerase chain reaction (RT-PCR) as previously described.13 All these analyses were carried out in three referral laboratories (Department of Cellular Biotechnology and Hematology, "La Sapienza" University, Rome; Department of Clinical and Biological Sciences, Orbassano, University of Turin; Department of Biochemistry and Medical Biotechnologies, Federico II University, Naples).
Multidrug resistance
MDR1 expression and function were assessed in the same laboratory (Department of Cellular Biotechnology and Hematology, "La Sapienza" University, Rome) by two cytometric tests, as described elsewhere.14 MDR1 expression was measured by flow cytometric detection of P-gp expression, which was considered positive when the D value was
0.05; MDR1 function was investigated using the rhodamine-123 efflux test, which was considered positive when values were 1.10 or greater.
Statistical analysis
A statistical analysis was performed taking into account gender, age, white blood cell count, hemoglobin level, platelet count, presence or absence of CD13, CD33 and CD34 antigens, cytogenetics, molecular biology and MDR. The cut-off levels for age, leukocytosis, anemia and thrombocytopenia used for statistical comparisons were derived from median values of our data and earlier studies that established significant correlations between these values and patients survival.15–17 Differences in the distributions of variables between groups of patients were analyzed by the Kruskal-Wallis,
2 or Fishers exact test. Overall survival (OS) from diagnosis and disease-free survival (DFS) from complete remission were estimated using the Kaplan-Meier method. The cumulative incidence of relapse was estimated using the appropriate non-parametric method. The log-rank test was applied to compare treatment effect and risk factor categories, using the Simon and Lee method 95% confidence intervals (95% CI) for these probabilities. Logistic regression and Cox proportional hazard regression models were performed to evaluate treatment results and risk factors affecting complete remission (CR) rate and time to event. The SAS software (SAS Institute, Cary, NC, USA) was used for the analyses.
| Results |
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2 cm) in 38.4%, splenomegaly (
2 cm) in 46.8% and lymphadenopathy in 55.6% of patients. The central nervous system was involved in 2.8% of patients. A mediastinal mass was present in 16.8% of patients; of these, 63% had T-lineage ALL and 37% B-lineage ALL. Eighty percent of patients was classified as having B-lineage ALL (pro-B ALL 20%, common-B ALL 64%, pre-B ALL 16%) and 20% as having T-lineage ALL (pro-T ALL 5%, pre-T ALL 46%, cortical-T ALL 38%, mature-T ALL 11%). CD13 and CD33 antigens were expressed in 25% and 23% of the 377 cases analyzed, respectively; thus aberrant MyAg (CD13 and/or CD33) expression was observed in 35% of all ALL cases. We also assessed whether the concomitant presence of the CD13 and CD33 antigens had a prognostic implication compared with individual positivity for CD13 or CD33. Since we found no differences, the results are reported according to the presence of CD13 and/or CD33.
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On the basis of the positivity for at least one of the two myeloid markers (CD13 and/or CD33), we stratified the patients into two groups: MyAg+ and MyAg– (Table 1). The presence of MyAg+ was significantly more frequent in females than in males (44.4% vs 28.6%; p=0.001). A difference was found with regard to the median white cell count (p=0.03) and the number of peripheral blasts (p=0.004), which were both lower in the MyAg+ group; a difference was also recorded in the median platelet count, which was higher in the MyAg+ group (p=0.004). No differences were found between the MyAg+ and MyAg–groups with regard to median age, median hemoglobin level, bone marrow findings (FAB and percentage of bone marrow blasts) and clinical features at presentation. MyAg were significantly more frequently associated with B-lineage ALL (38%) than with T-ALL (24%) (p=0.02) and, when considered according to immunophenotypic subtype were significantly more frequently associated with common ALL (52%; p=0.05) and pre-T ALL (50%; p=0.07). CD34 expression was found in 43% of MyAg+ and in 15% of MyAg– cases (p<0.0001).
No difference was observed in the expression of MyAg between the groups of patients with normal or abnormal cytogenetics. In high risk B-lineage ALL (BCR-ABL+, ALL1-AF4+, E2A-PBX1+), no difference was observed in the expression of MyAg and the presence of the BCR/ABL rearrangement or of the E2A/PBX1 rearrangement; however, in the same group, the absence of MyAg was strongly associated with the ALL1/AF4 rearrangement (p<0.0001). An equivalent expression of MyAg was recorded in all MDR+ and MDR– ALL cases, both with respect to MDR expression (32% vs 33%) and MDR function (43% vs 31%). Furthermore, no differences were recorded when the expression of MyAg was analyzed in MDR+ and MDR– patients subdivided according to B- or T-cell lineage affiliation.
The clinical course of MyAg+ and MyAg– patients is summarized in Table 2. The presence of aberrant MyAg did not affect the achievement of CR or cumulative incidence of relapse; no differences were found between MyAg+ and MyAg– cases in terms of DFS and OS at 5 years. In addition, we failed to observe any statistical difference between the two groups in the incidence of death either during induction or in CR. We also separately analyzed MyAg expression in T-ALL and B-lineage ALL cases according to the following subgroups: (i) MyAg+ in high risk B-lineage ALL, (ii) MyAg– in high risk B-lineage ALL; (iii) MyAg+ in B-lineage ALL without known transcripts; (iv) MyAg– in B-lineage ALL without known transcripts; (v) and MyAg+ in T-lineage ALL; and (vi) MyAg– in T-lineage ALL. No differences in CR achievement, OS and DFS were recorded between MyAg+ and MyAg– cases in the different ALL subgroups (Figure 2). Furthermore, when cases with B-lineage ALL with BCR/ABL rearrangement were analyzed as a separate group, we found no differences in CR achievement, OS and DFS between MyAg+ and MyAg– cases. In addition, in B-lineage ALL, we analyzed MyAg expression according to immunophenotypic subtypes (pro-B ALL MyAg+ vs pro-B ALL MyAg–; common-B ALL MyAg+ vs common-B MyAg–; pre-B ALL MyAg+ vs pre-B MyAg–) once again finding no differences between MyAg+ and MyAg– groups in CR achievement, DFS and OS, even if a higher probability of OS was recorded in the pro-B MyAg– group (p=0.06). A multivariate analysis including clinical and biological data was performed to determine the prognostic value of MyAg and CD34 expression; no specific effect on CR, DFS or OS could be found (data not shown).
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| Discusssion |
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In the present study we examined the impact of aberrant MyAg expression on prognosis in a cohort of 377 adult patients treated uniformly with the GIMEMA ALL 0496 protocol, the largest series so far investigated. The presence of MyAg was correlated with a number of clinical and biological data. Among the clinical data, a difference was found only for white cell count (p=0.03), percentage of peripheral blasts (p=0.004) and platelet count (p=0.004). Among the biological data, there was a statistical difference in the incidence of aberrant MyAg expression between B-lineage ALL and T-ALL subgroups (p=0.02), and a significant association with the expression of the CD34 antigen (p<0.0001). We have previously reported18 that in T-ALL patients MyAg positivity and/or CD34 positivity and/or MDR positivity (as evaluated by function) shows a highly negative association with CR achievement. The same association in the subgroup with B-lineage ALL did not correlate with response to therapy. We separately analyzed the presence of MyAg in T and B-lineage ALL cases, and failed to find any difference in CR achievement, OS or DFS.
Even if the absence of MyAg expression was strictly associated with the ALL1/AF4+ rearrangement (p<0.0001), the small number of patients prevents any firm conclusions from being reached. Besides, in univariate analysis, we found no significant differences in CR, DFS and OS between the MyAg+ and MyAg– groups with BCR/ABL and E2A/PBX1 rearrangements. In addition, we also analyzed the value of CD34 antigen as a separate parameter and found no prognostic significance in either univariate or multivariate analysis.
The overall incidence of MyAg expression in our study (35%) is in line with the data reported in the literature. Our results suggest that there are no differences between MyAg+ and MyAg– groups in terms of CR, DFS and OS, in either B- or T-lineage ALL. These findings are likely to be due to the more intensive treatment modalities adopted in the GIMEMA ALL 0496 protocol which is characterized by high-dose daunorubicin during the induction phase and by high-dose aracytin in the post-remission phase. In conclusion, when analyzed homogeneously and prospectively in a large cohort of uniformly characterized and treated adult ALL cases, the expression of MyAg alone does not bear short and long-term prognostic significance. Nonetheless, the evaluation of the expression of these antigens and the level of antigenic expression remains valuable for a more precise characterization of the leukemic population in each individual patient. This has clinical implications in terms of therapeutic decisions (e.g. anti-CD33 treatment) and for monitoring minimal residual disease during the course of the disease.
| Appendix |
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| Acknowledgments |
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| Footnotes |
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AV: wrote the manuscript, coordinated central sample handling, analyzed immunologic data, revision of statistical data; AG: analyzed immunologic data, revised the manuscript; CA: central sample handling, revision of statistical data; GM: patient management, provided clinical samples and clinical information; OP: analyzed immunologic data; MP: patient management, provided clinical samples and clinical information; CFG: patient management, provided clinical samples and clinical information; VM: patient management, provided clinical samples and clinical information; AP: patient management, provided clinical samples and clinical information; GP: analyzed immunologic data, revised the manuscript; MV: writing and design of the protocol, collection and statistical analyses of the data; FM: GIMEMA chairman; RF: designed research and supervised the manuscript, biological study coordinator.
The authors reported no potential conflicts of interest.
Funding: Supported by the Associazione Italiana per la Ricerca sul Cancro (AIRC), Istituto Superiore di Sanità (ISS), Ministero dellIstruzione, Università e della Ricerca Scientifica, Progetto FIRB (Fondo per gli Investimenti della Ricerca di Base), Progetto COFIN and the Roman Section of the Italian Association Against Leukemia (ROMAILONLUS).
Received for publication June 8, 2006. Accepted for publication December 12, 2006.
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