Richard Ratei

Risk-Adjusted Therapy of Acute Lymphoblastic Leukemia Can Decrease Treatment Burden and Improve Survival: Treatment Results of 2169 Unselected Pediatric and Adolescent Patients Enrolled in the Trial ALL-BFM 95.

The trial ALL-BFM 95 for treatment of childhood acute lymphoblastic leukemia was designed to reduce acute and long-term toxicity in selected patient groups with favorable prognosis and to improve outcome in poor-risk groups by treatment intensification. These aims were pursued through a stratification strategy using white blood cell count, age, immunophenotype, treatment response, and unfavorable genetic aberrations providing an excellent discrimination of risk groups. Estimated 6-year event-free survival (6y-pEFS) for all 2169 patients was 79.6% (+/- 0.9%). The large standard-risk (SR) group (35% of patients) achieved an excellent 6y-EFS of 89.5% (+/- 1.1%) despite significant reduction of anthracyclines. In the medium-risk (MR) group (53% of patients), 6y-pEFS was 79.7% (+/- 1.2%); no improvement was accomplished by the randomized use of additional intermediate-dose cytarabine after consolidation. Omission of preventive cranial irradiation in non-T-ALL MR patients was possible without significant reduction of EFS, although the incidence of central nervous system relapses increased. In the high-risk (HR) group (12% of patients), intensification of consolidation/reinduction treatment led to considerable improvement over the previous ALL-BFM trials yielding a 6y-pEFS of 49.2% (+/- 3.2%). Compared without previous trial ALL-BFM 90, consistently favorable results in non-HR patients were achieved with significant treatment reduction in the majority of these patients.

Risk of Relapse of Childhood Acute Lymphoblastic Leukemia Is Predicted By Flow Cytometric Measurement of Residual Disease on Day 15 Bone Marrow

PURPOSE Speed of blast clearance is an indicator of outcome in childhood acute lymphoblastic leukemia (ALL). Availability of measurement of minimal residual disease (MRD) at an early time point with a reduced-cost method is of clinical relevance. In the AIEOP-BFM-ALL (Associazione Italiana Ematologia Oncologia Pediatrica and Berlin-Frankfurt-Münster Study Group) 2000 trial, patients were stratified by levels of polymerase chain reaction (PCR) MRD at day +33 and +78. AIEOP studied the prognostic impact of MRD measured by flow cytometry (FCM) at day 15 of induction therapy. PATIENTS AND METHODS Bone marrow samples from 830 Italian patients were collected on day 15, after 14 days of steroids, and one dose of intrathecal methotrexate, vincristine, daunorubicine, and asparaginase. Cells were analyzed by four-color FCM for detection of leukemia-associated immunophenotypes. RESULTS Three patient risk groups were identified by FCM: standard (< 0.1% blast cells; 42% of the total), intermediate (0.1 to < 10%; 47%), and high (> or = 10%; 11%). Their 5-year cumulative incidences of relapse were 7.5% (SE, 1.5), 17.5% (SE, 2.1), and 47.2% (SE, 5.9), respectively. In multivariate analysis, FCM was the most important prognostic factor among those available by day 15, with two-fold and five-fold increase in the risk of relapse compared with patients with less than 0.1%. PCR MRD, when added to the model, had significant prognostic impact; yet high levels of FCM MRD retained an independent ability to detect a significantly higher risk of relapse. CONCLUSION Measurement of FCM MRD in day 15 bone marrow was the most powerful early predictor of relapse, applicable to virtually all patients; it may complement PCR MRD-based stratification including later time points, thus allowing additional treatment tailoring.

Long-Term Outcome in Children With Relapsed Acute Lymphoblastic Leukemia After Time-Point and Site-of-Relapse Stratification and Intensified Short-Course Multidrug Chemotherapy: Results of Trial ALL-REZ BFM 90

PURPOSE The multicenter trial ALL-REZ BFM (ie, Acute Lymphoblastic Leukemia Relapse Berlin-Frankfurt-Münster) 90 was designed to improve prognosis for children with relapsed acute lymphoblastic leukemia (ALL) by time-to-relapse- and site-of-relapse-adapted stratification and by introduction of novel chemotherapy elements and to evaluate new prognostic parameters in a large, population-based cohort. PATIENTS AND METHODS Five hundred twenty-five patients stratified into risk groups A (early bone marrow [BM] relapses), B (late BM relapses), and C (isolated extramedullary relapses) received alternating short-course intensive polychemotherapy (in blocks R1, R2, or R3) and cranial/craniospinal irradiation followed by maintenance therapy. Block R3 (high-dose cytarabine and etoposide) was introduced to improve the outcome compared with historical controls. Patients with early BM or T-ALL relapse (poor prognosis group [PPG]) were eligible for experimental regimens. One hundred seventeen patients received stem-cell transplantation (SCT). RESULTS The probabilities (and standard deviations) of event-free survival (pEFS) and overall survival (pOS) at 10 years were 0.30 +/- .02 and 0.36 +/- .02, respectively. Significant differences existed between strategic groups (pEFS(A) = .17 +/- .03; pEFS(B) = .43 +/- .04; pEFS(C) = .54 +/- .06; pEFS(PPG) = .15 +/- .03; log-rank P < .001). Patients of high-risk groups A plus PPG did better with SCT than with chemotherapy (pEFS = .33 +/- .05 v 0.20 +/- .05; P = .005). The pEFS was similar to trials ALL-REZ BFM 85/87 (.36 +/- .03. v 0.37 +/- .03; P = .419; PPG excluded). Time point, site of relapse, immunophenotype, and SCT were significant predictors of pEFS in multivariate analyses. CONCLUSION More than one third of patients in this large, population-based trial were cured. Neither R3 nor adaptation of chemotherapy intensity was capable of improving pEFS or of overcoming prognostic factors. In high-risk patients, remission induction regimens must be improved, and allogeneic SCT should be recommended in patients achieving second complete remission.

Drug-induced immunophenotypic modulation in childhood ALL: implications for minimal residual disease detection.

Assessment of minimal residual disease (MRD) by flow cytometry is considered to be based on the reproducibility of the leukemic immunophenotype detected at diagnosis. However, we previously noticed modulation of surface antigen expression in acute lymphoblastic leukemia (ALL) during the early treatment. Hence, we investigated this in 30 children with B-cell precursor ALL consecutively enrolled in the AIEOP-BFM ALL 2000 protocol. Quantitative expression of seven antigens useful in MRD monitoring was studied at diagnosis and compared to that measured at different time points of remission induction therapy. Downmodulation in the expression of CD10 and CD34 occurred at follow-up. By contrast, upmodulation of CD19, CD20, CD45RA, and CD11a was observed, while the expression of CD58 remained stable. Despite this, we could unambiguously discriminate leukemic cells from normal residual B cells. This holds true when bone marrow (BM) samples from similarly treated T-ALL patients, but not from healthy donors, were used as reference. Our results indicate that immunophenotypic modulation occurs in ALL during the early phases of BFM-type protocols. However, the accuracy of MRD detection by flow cytometry seems not negatively affected if adequate analysis protocols are employed. Investigators should take this phenomenon into account in order to avoid pitfalls in flow cytometric MRD studies.

CD20 up-regulation in pediatric B-cell precursor acute lymphoblastic leukemia during induction treatment: setting the stage for anti-CD20 directed immunotherapy

CD20 is expressed in approximately one- half of pediatric acute lymphoblastic leukemia (ALL) cases with B-cell precursor (BCP) origin. We observed that it is occasionally up-regulated during treatment. To understand the impact of this on the potential effectiveness of anti-CD20 immunotherapy, we studied 237 CD10(+) pediatric BCP-ALL patients with Berlin-Frankfurt-Munster (BFM)-type therapy. We analyzed CD20 expression changes from diagnosis to end-induction, focusing on sample pairs with more than or equal to 0.1% residual leukemic blasts, and assessed complement-induced cytotoxicity by CD20-targeting with rituximab in vitro. CD20-positivity significantly increased from 45% in initial samples to 81% at end-induction (day 15, 71%). The levels of expression also increased; 52% of cases at end-induction had at least 90% CD20(pos) leukemic cells, as opposed to 5% at diagnosis (day 15, 20%). CD20 up-regulation was frequent in high-risk patients, patients with high minimal residual disease at end-induction, and patients who suffered later from relapse, but not in TEL/AML1 cases. Notably, up-regulation occurred in viable cells sustaining chemotherapy. In vitro, CD20 up-regulation significantly enhanced rituximab cytotoxicity and could be elicited on prednisolone incubation. In conclusion, CD20 up-regulation is frequently induced in BCP-ALL during induction, and this translates into an acquired state of higher sensitivity to rituximab. This study was registered at http://www.clinicaltrials.gov as #NCT00430118.

High single-drug activity of nelarabine in relapsed T-lymphoblastic leukemia/lymphoma offers curative option with subsequent stem cell transplantation

Nelarabine, a purine analog with T-cell specific action, has been approved for relapsed/refractory T-cell acute lymphoblastic leukemia/lymphoma (ALL/LBL). This is a report of a single-arm phase 2 study conducted in adults (18-81 years of age) with relapsed/refractory T-ALL/LBL. After 1 or 2 cycles, 45 of 126 evaluable patients (36%) achieved complete remission (CR), 12 partial remission (10%), and 66 (52%) were refractory. One treatment-related death was observed, and 2 patients were withdrawn before evaluation. A total of 80% of the CR patients were transferred to stem cell transplantation (SCT). Overall survival was 24% at 1 year (11% at 6 years). After subsequent SCT in CR, survival was 31% and relapse-free survival 37% at 3 years. Transplantation-related mortality was 11%. Neurologic toxicities of grade I-IV/grade III-IV were observed in 13%/4% of the cycles and 16%/7% of the patients. This largest study so far with nelarabine in adults showed impressive single-drug activity in relapsed T-ALL/T-LBL. The drug was well tolerated, even in heavily pretreated patients. A high proportion of CR patients were transferred to SCT with low mortality but a high relapse rate. Exploration of nelarabine in earlier stages of relapse (eg, increasing minimal residual disease), in front-line therapy, and in combination is warranted.

Standardization of flow cytometric minimal residual disease evaluation in acute lymphoblastic leukemia: Multicentric assessment is feasible†‡

Single‐laboratory experience showed that flow cytometric (FCM) assessment of minimal residual disease (MRD) in acute lymphoblastic leukemia (ALL) is feasible in most patients and gives independent prognostic information. It is, however, not known whether FCM analysis can reliably be standardized for multicentric application.

IKZF1 deletion is an independent predictor of outcome in pediatric acute lymphoblastic leukemia treated according to the ALL-BFM 2000 protocol

IKZF1 gene deletions have been associated with a poor outcome in pediatric precursor B-cell acute lymphoblastic leukemia. To assess the prognostic relevance of IKZF1 deletions for patients treated on Berlin-Frankfurt-Münster Study Group trial ALL-BFM 2000, we screened 694 diagnostic acute lymphoblastic leukemia samples by Multiplex Ligation-dependent Probe Amplification. Patients whose leukemic cells bore IKZF1 deletions had a lower 5-year event-free survival (0.69±0.05 vs. 0.85±0.01; P<0.0001) compared to those without, mainly due to a higher cumulative incidence of relapses (0.21±0.04 vs. 0.10±0.01; P=0.001). Although IKZF1 deletions were significantly associated with the P2RY8-CRLF2 rearrangement, their prognostic value was found to be independent from this association. Thus, IKZF1 deletion is an independent predictor of treatment outcome and a strong candidate marker for integration in future treatment stratification strategies on ALL-BFM protocols. Clinicaltrials.gov identifier: NCT00430118

Clinical significance of CD95, Bcl-2 and Bax expression and CD95 function in adult de novo acute myeloid leukemia in context of P-glycoprotein function, maturation stage, and cytogenetics

Resistance to chemotherapy-induced apoptosis and a multidrug-resistance (MDR) phenotype, mainly mediated by P-glycoprotein (P-gp), contribute to chemotherapy failure in hematologic malignancies. To study apoptosis-regulating factors in acute myeloid leukemia (AML), we investigated cell samples of adults with de novo AML by flow cytometry for constitutive expression levels of the apoptosis-related molecules CD95 (n = 135), Bcl-2 (n = 131), and Bax (n = 66), as well as spontaneous apoptosis in vitro (n = 104) and susceptibility to anti-CD95-induced apoptosis (CD95 sensitivity) (n = 93). We correlated these findings with P-gp function as detected by the rhodamine123-efflux test (n = 121), immunophenotype, FAB morphology, cytogenetics, and clinical data of the examined patients. Immature FAB M0/1 AML cells expressed significantly more Bcl-2 (P < 0.0002) and less cd95 (P < 0.0003) compared with aml cells of the more mature fab m2–5 subtypes. no maturation-dependent difference in bax expression was observed. fab m2–5 aml cells were more susceptible to anti-cd95-induced apoptosis (P < 0.008) and showed a lower p-gp function (P < 0.002) than fab m0/1 aml cells. leukemic cells of aml patients who achieved a complete remission (cr) after induction chemotherapy expressed less bcl-2 than non-responder (nr) (69 cr, 23 nr; P = 0.05). CR was associated with a higher extent of spontaneous apoptosis in vitro (58 CR, 17 NR; P=0.05) and a tendency towards a higher CD95 expression (73 CR, 23 NR; P = 0.08) compared to NR. CR also correlated with a low P-gp function (70 CR, 21 NR; P = 0.008) and a tendency towards CD34 negativity (73 CR, 23 NR; P = 0.08). No correlation between Bax expression and response to induction chemotherapy (49 CR, 12 NR) was observed. In stepwise logistic regression analyses, P-gp function and the extent of spontaneous apoptosis in vitro as well as CD95 sensitivity but not Bcl-2, CD95, Bax, and CD34 expression levels emerged as significant markers for response to induction chemotherapy. We conclude that the constitutive expression of CD95 and Bcl-2, as well as CD95 sensitivity and P-gp function but not constitutive Bax expression depend on the maturation stage of leukemic cells in adult de novo AML. P-gp function, the extent of spontaneous apoptosis in vitro and CD95 sensitivity are more predictive for response to induction chemotherapy in adult de novoAML than the constitutive expression levels of the apoptosis-related molecules CD95, Bcl-2 and Bax.

CD99 expression in T-lineage ALL: implications for flow cytometric detection of minimal residual disease

Expression of CD99 is higher on immature than on mature T cells. We postulated that this marker could be used to assess minimal residual disease (MRD) in T-lineage acute lymphoblastic leukemia (T-ALL). In diagnostic bone marrow (BM) samples from 27 children with T-ALL, expression of CD99 on leukemic lymphoblasts by flow cytometry was in median 7.7 times higher than on normal T lymphocytes from within the same sample. In 85% of cases, leukemic MFI values were higher than the mean MFI+2 s.d. of normal populations. We applied CD99 to study MRD in 39 follow-up samples from 15 consecutive T-ALL patients, and compared the results with those obtained with the well-established MRD-marker terminal deoxynucleotidyl transferase (TdT). Either antibody was combined in four-color flow cytometry with CD7, surfaceCD3, and cytoplasmicCD3. We found that CD99 was a valid complement to TdT in quantifying T-ALL MRD. Given a considerable interpatient variability, CD99 could be favorably used in nine patients, and TdT in other five patients. Both approaches showed a similar very low nonspecific background throughout 12 weeks from diagnosis (in median 0.002% of nucleated BM cells in patients with non-T ALL). We conclude that CD99 is a highly informative tool for MRD detection in T-ALL, bearing the advantage of surface expression in contrast to TdT.