The immunophenotype in infant acute lymphoblastic leukaemia: correlation with clinical outcome. An Italian multicentre study (AIEOP)

Profile of Acute Lymphoblastic Leukemia in Children Under 2 Years of Age

Context: Acute lymphoblastic leukemia (ALL) shows substantial differences in clinical and laboratory features and treatment responsiveness in different subgroups. Pediatric ALL <2 years is associated with worse outcome. Infantile ALL is characterized by high white blood cell (WBC) counts, bulky extramedullary disease, translocations of 11q23 locus. There is paucity of data on ALL under 2 years of age. Aims: This study aims to analyze clinical, hematological, biochemical, immunophenotypical parameters, and treatment responsiveness of ALL under 2 years. Settings and Designs: It is a retrospective data analysis conducted at a Tertiary Care Cancer Centre in South India. The study population includes all pediatric ALL, registered at this institute during January 2009 to December 2013, who were under 2 years at the time of presentation. Materials and Methods: There were 122 cases of ALL under 2 years of age of whom 48 refused treatment, and four were lost to follow-up. Thus, 70 cases are eligible for analysis. Details on clinical, hematological, biochemical, radiological, immunophenotypical, and cytogenetic features were collected from case records, hospital cancer registry, and analysis done using SPSS version 20. Kaplan–Meier curves plotted for survival analysis. Results:: Male:female ratio was 1.26:1 (infants - 1:1; 1–2 years group - 1.3:1). The most common clinical features were hepatomegaly (95%) and fever (89%). Hemoglobin level >11 gm% was seen in 12%, WBC counts above 50,000 in 26% and platelets below 20,000 in 20%. Elevated lactate dehydrogenase presents in 64% and uric acid in 12%. Immunophenotype done in 44 children; precursor-B ALL-41, precursor-T ALL-3. Central nervous system -positive disease and 11q23 translocation were noted in one infant each. Conclusions: Infants with ALL are associated with poor prognosis. Children in the 1–2 years are associated with significantly better outcome. WBC counts >50,000 are associated with poor prognosis among infants. Treatment refusal/abandonment rate is 43% in the study population which is comparable to that in literature.

Intensified chemotherapy without SCT in infant ALL: results from COG P9407 (Cohort 3)

BACKGROUND

Infants with acute lymphoblastic leukemia (ALL) present with aggressive disease and a poor prognosis. Early relapse within 6-9 months of diagnosis is common. Approximately 75% of infants have MLL-rearranged (MLL-R) ALL with event free survival (EFS) ranging from 20% to 30%. Children's Oncology Group (COG) P9407 used shortened (46 weeks), intensified therapy to address early relapse and poor EFS.

PROCEDURE

P9407 therapy was modified three times for induction toxicity resulting in three cohorts of therapy. One hundred forty-seven infants were enrolled in the third cohort.

RESULTS

We report an overall 5-year EFS and OS of 42.3 ± 6% and 52.9 ± 6.5% respectively. Poor prognostic factors included age ≤90 days at diagnosis, MLL-R ALL and white cell count ≥50,000/μl. For infants ≤90 days of age, the 5-year EFS was 15.5 ± 10.1% and 48.5 ± 6.7% for those >90 days (P < 0.0001). Among infants >90 days of age, 5-year EFS rates were 43.8 ± 8% for MLL-R versus 69.1 ± 13.6% for MLL-germline ALL (P < 0.0001).

CONCLUSIONS

Age ≤90 days at diagnosis was the most important prognostic factor. Despite shortened therapy with early intensification, EFS remained less than 50% overall in MLL-R ALL.

Myeloid Antigen Expression in Childhood Acute Lymphoblastic Leukemia and Its Relevance for Clinical Outcome in Indonesian ALL-2006 Protocol

The frequency of acute lymphoblastic leukemia (ALL) patients expressing myeloid antigens on their ALL cells varies between 5 and 36% in several different studies. The clinical relevance of myeloid antigen expression in childhood ALL is controversial. In Indonesian patients, no data were present. Therefore, in Yogyakarta, Indonesia, we analyzed 239 ALL patients who were immunophenotyped including myeloid markers (CD13, CD33, CD117, and/or cMPO). Myeloid antigen expression was found in 25% of patients. Expression of myeloid antigen in B-lineage leukemia was 27%, and in T-lineage leukemia, it was 18% (P = 0.15). No association was found between myeloid antigen expression and clinical or biological features. In the whole cohort of patients we did not find a significant association between myeloid antigen expression and survival, although leukemia-free survival at 3 years was higher in the myeloid-negative patients (73% ± 6%) compared to myeloid-positive patients (67% ± 8%). Interestingly, in T-ALL patients, expression of myeloid antigens was an independent adverse prognostic factor (hazard ratio: 3.26, 95% CI: 1.06–9.98, P = 0.04). Kaplan-Meier analysis for event-free survival was also significant (log rank P = 0.03) in this subgroup. In conclusion, in the Indonesian ALL population, in particular, myeloid antigen-expressing T-ALL patients had a higher chance of having induction failure.

Application of flow cytometry in pediatric hematology-oncology

Applications of flow cytometry in pediatric cancers have expanded substantially in recent years. In acute leukemias, the commonest childhood cancer, flow cytometry can now define complex antigenic profiles that are associated with specific cytogenetic/molecular defects and can also directly identify BCR-ABL fusion protein. Flow cytometry based scoring system has been described for diagnosis of myelodysplastic syndromes. In solid tumors, flow cytometry was previously used mainly to determine DNA content for prognosis; however, recent studies in children with neuroblastoma and Ewing sarcoma have identified its diagnostic utility. In this review, we will discuss the current and future applications of flow cytometry in pediatric hematology-oncology.

Analysis of infectious complications in infants with acute lymphoblastic leukemia treated on the Children's Cancer Group Protocol 1953: a report from the Children's Oncology Group

Infants with acute lymphoblastic leukemia have a poor prognosis. The Children's Cancer Group (CCG) 1953 protocol tested the hypothesis that intensification of therapy would improve outcome for these patients. This intensified therapy resulted in better disease control, but resulted in greater toxicity. In this paper, we report the infectious complications associated with this intensified therapy. We retrospectively analyzed the infectious complications reported on the case report forms of all 115 patients enrolled on CCG 1953. Overall 495 infectious complications were identified in 115 patients. Bacterial infections occurred most frequently (74%), followed by viral (13%), fungal (11%), and protozoan (1%). Infection related mortality disproportionately occurred with viral (31%) and fungal (19%) infections. Twenty-three percent (n=26) of patients died of infectious complications, with the majority occurring during induction/intensification. Lower respiratory infections contributed to death in 12 patients and were most commonly viral (n=6) and fungal (n=3). Intensification of therapy resulted in increased infectious complications and deaths compared with previous studies. Future studies will need to focus on: (1) decreasing intensification during the first month of therapy, (2) developing targeted therapies, and (3) improving measures designed to prevent, quickly diagnose, and appropriately treat infections.

Analysis of prognostic factors of acute lymphoblastic leukemia in infants: report on CCG 1953 from the Children's Oncology Group

Infant acute lymphoblastic leukemia (ALL) has a poor therapeutic outcome despite attempts to treat it based on prognostic factor-guided therapy. This is the first cooperative group trial characterizing all infants at the molecular level for MLL/11q23 rearrangement. All infants enrolled on Children's Cancer Group (CCG) 1953 were tested for MLL rearrangement by Southern blot and the 11q23 translocation partner was identified (4;11, 9;11, 11;19, or "other") by reverse-transcriptase polymerase chain reaction (PCR). One hundred fifteen infants were enrolled; overall event-free survival (EFS) was 41.7% (SD = 9.2%) and overall survival (OS) was 44.8% at 5 years. Five-year EFS for MLL-rearranged cases was 33.6% and for MLL-nonrearranged cases was 60.3%. The difference in EFS between the 3 major MLL rearrangements did not reach statistical significance. Multivariate Cox regression analyses showed a rank order of significance for negative impact on prognosis of CD10 negativity, age younger than 6 months, and MLL rearrangement, in that order. Toxicity was the most frequent cause of death. Relapse as a first event in CCG 1953 was later (median, 295 days) compared with CCG 1883 historic control (median, 207 days). MLL/11q23 rearrangement, CD10 expression, and age are important prognostic factors in infant ALL, but molecular 11q23 translocation partners do not predict outcome.

Towards targeted therapy for infant acute lymphoblastic leukaemia

Despite the greatly improved treatment regimes for childhood acute lymphoblastic leukaemia (ALL) in general, resulting in long-term survival in approximately 80% of cases, current therapies still fail in >50% of ALL cases diagnosed within the first year of life (i.e. in infants). Therefore, more adequate treatment strategies are urgently needed to also improve the prognosis for these very young patients with ALL. Here we review the current acquaintance with the biology of infant ALL and describe how this knowledge may lead to innovative therapeutic approaches.

Fetal and neonatal leukemia

The biological and clinical characteristics of perinatal leukemia differ significantly from those of leukemia in older children, and the prognosis is generally bleak. Once complete remission is achieved, neonates with acute myelocytic leukemia (AML) fare much better than those with acute lymphocytic leukemia (ALL). The results of this study suggest that age, sex, type of leukemia, and cytogenetic findings have a strong influence on outcome. Neonates, particularly females, with pre-B ALL have a much worse prognosis than neonates and older children with this disease. Transient leukemia in the Down syndrome neonate is associated with significant morbidity; close follow-up is recommended for at least the first 3 years of life because of the potential of developing acute leukemia, particularly AMKL (M7). The purpose of this review is to focus on the fetus and neonate in an attempt to determine the various ways leukemia differs clinically and morphologically from the disease occurring in older infants and children and to demonstrate that certain types of leukemia have a poor prognosis compared with those occurring in older children.

Immunophenotypic analysis of acute lymphocytic leukemia

Acute lymphoblastic leukemia (ALL) is one of the most common hematologic malignancies. Flow cytometry is an integral part of ALL diagnosis and also provides significant patient prognostic information. This article is a practical review of the basic principles of the flow cytometric evaluation of acute leukemias, the interpretation of flow cytometric data, and the management of practical problems such as aberrant antigen, hematogones, bone marrow regeneration, and minimal residual disease.

Central nervous system-directed therapy in the treatment of childhood acute lymphoblastic leukemia and studies of neurobehavioral outcome: Children's Cancer Group trials

Long-term survival rates in childhood acute lymphoblastic leukemia (ALL) have improved due, in part, to the introduction and subsequent refinements in central nervous system (CNS)-directed therapy. Studies of cognitive, motor, and behavioral functioning, which characterize the patterns and severity of CNS sequelae, are being used increasingly as measurable treatment endpoints. This paper summarizes the advances in CNS-directed therapy derived from Children's Cancer Group randomized therapeutic trials. Results from neurobehavioral outcome studies built upon these trials are also presented. A section of this review is focused on CNS-directed treatments and the neurodevelopmental outcomes of infants diagnosed with ALL, an especially high-risk patient subset. Future studies of neurobehavioral outcome are briefly elaborated in the context of current chemotherapy approaches used in the treatment of childhood ALL.

Prednisone Response Is the Strongest Predictor of Treatment Outcome in Infant Acute Lymphoblastic Leukemia

To define prognostic factors in infant acute lymphoblastic leukemia (ALL), the outcome of 106 infants (age ≤12 months) during 3 consecutive multicenter trials of the Berlin-Frankfurt-Münster group (ALL-BFM 83, 86, and 90) was retrospectively analyzed according to presenting features and early in vivo response to prednisone. The prednisone response was defined as the cytoreduction (number of blood blasts per microliter at day 8) to a 7-day prednisone prephase and 1 intrathecal dose of methotrexate on day 1. Prednisone good responder (PGR; <1,000 blasts/μL) received conventional therapy and prednisone poor responder (PPR; ≥1,000 blasts/μL) received intensified therapy. Infant ALL was characterized by a high incidence of a white blood cell count greater than 100 × 103/μL (57%), central nervous system leukemia (24%), lack of CD10 expression (59%), 11q23 rearrangement (49%) including the translocation t(4;11) (29%), and a comparatively high proportion of PPR (26%), which were all significantly associated with inferior outcome by univariate analysis. The estimated probability for an event-free survival at 6 years (pEFS) was by far better for PGR compared with PPR, who had a dismal prognosis despite intensified treatment (pEFS, 53% ± 6%v 15% ± 7%, P = .0001). Infant PGR, who were less than 6 months of age (n = 40), lacked CD10 expression (n = 43), and/or had an 11q23 rearrangement (n = 17) fared significantly better compared with corresponding PPR, as indicated by a pEFS of 44% ± 8%, 49% ± 8%, and 41% ± 12%, respectively. In multivariate analysis, PPR was the strongest adverse prognostic factor (relative risk, 3.3; 95% confidence interval, 1.9 to 5.8; P< .0001). Infants with PGR, comprising a major subgroup (74%) among infants, might successfully be treated with conventional therapy, whereas PPR require new therapeutic strategies, including early treatment intensification or bone marrow transplantation in first remission.

Prednisone Response Is the Strongest Predictor of Treatment Outcome in Infant Acute Lymphoblastic Leukemia

To define prognostic factors in infant acute lymphoblastic leukemia (ALL), the outcome of 106 infants (age ≤12 months) during 3 consecutive multicenter trials of the Berlin-Frankfurt-Münster group (ALL-BFM 83, 86, and 90) was retrospectively analyzed according to presenting features and early in vivo response to prednisone. The prednisone response was defined as the cytoreduction (number of blood blasts per microliter at day 8) to a 7-day prednisone prephase and 1 intrathecal dose of methotrexate on day 1. Prednisone good responder (PGR; &lt;1,000 blasts/μL) received conventional therapy and prednisone poor responder (PPR; ≥1,000 blasts/μL) received intensified therapy. Infant ALL was characterized by a high incidence of a white blood cell count greater than 100 × 103/μL (57%), central nervous system leukemia (24%), lack of CD10 expression (59%), 11q23 rearrangement (49%) including the translocation t(4;11) (29%), and a comparatively high proportion of PPR (26%), which were all significantly associated with inferior outcome by univariate analysis. The estimated probability for an event-free survival at 6 years (pEFS) was by far better for PGR compared with PPR, who had a dismal prognosis despite intensified treatment (pEFS, 53% ± 6%v 15% ± 7%, P = .0001). Infant PGR, who were less than 6 months of age (n = 40), lacked CD10 expression (n = 43), and/or had an 11q23 rearrangement (n = 17) fared significantly better compared with corresponding PPR, as indicated by a pEFS of 44% ± 8%, 49% ± 8%, and 41% ± 12%, respectively. In multivariate analysis, PPR was the strongest adverse prognostic factor (relative risk, 3.3; 95% confidence interval, 1.9 to 5.8; P&lt; .0001). Infants with PGR, comprising a major subgroup (74%) among infants, might successfully be treated with conventional therapy, whereas PPR require new therapeutic strategies, including early treatment intensification or bone marrow transplantation in first remission.

Congenital and neonatal leukemia

Congenital and neonatal leukemia occur rarely, yet carry high mortality rates and pose special problems for the perinatologist and hematologist. Although the etiology is unknown, the presence of leukemia at birth suggests genetic abnormalities and possibly intrauterine exposures to drugs or other toxins as contributing factors. Specific chromosomal rearrangements that are common in congenital leukemia have recently been identified and promise to enhance our understanding of these enigmatic diseases. The differential diagnosis is broad and includes many disorders that occur frequently in the neonatal period. Infants diagnosed with congenital or neonatal leukemia require thorough investigative workup and extensive supportive care. Although the prognosis is poor, recent use of high-intensity multiagent chemotherapy regimens has produced promising results.

Myeloid antigen co-expression in childhood acute lymphoblastic leukaemia: relationship with in vitro drug resistance

Contradictory data have been reported about the prognostic value of myeloid antigen co-expression (My+) in childhood acute lymphoblastic leukaemia (ALL). In the present study the methyl thiazol tetrazoliumbromide (MTT) assay was used to compare the in vitro cytotoxicity of 14 drugs between 60 My+ (CD13+ and/or CD33+) and 107 My- ALL children at initial diagnosis. P-glycoprotein (P-gp), multidrug resistance-associated protein (MRP), major vault protein/lung resistance protein (LRP) and the intracellular daunorubicin concentration were studied by flow cytometry. My+ ALL samples were significantly more resistant, i.e. between 1.1- and 2.9-fold, to daunorubicin, doxorubicin, idarubicin, mitoxantrone, vincristine, 6-thioguanine, 6-mercaptopurine, teniposide, etoposide and ifosfamide compared with My- ALL samples. My- and My+ ALL did not significantly differ in sensitivity to prednisolone, dexamethasone, L-asparaginase and cytarabine. Comparable results were found when only common and preB ALL cases were analysed. Drug resistance in My+ ALL was not related to increased expression of P-gp, MRP or LRP compared with My- ALL (ratio My+/My-:P-gp 0.8, MRP 1.0, LRP 1.1). Accumulation and retention of daunorubicin did not significantly differ between My- and My+ ALL cells (ratio My+/My-: accumulation 1.2, retention 1.3). Therefore the nature of drug resistance in My+ ALL remains unknown. The lack of prognostic value for My+ in childhood ALL may be explained by the responsiveness of My+ ALL to glucocorticoids, L-asparaginase and cytarabine. In addition, the currently intensive treatment regimens may apply drug doses which are simply high enough to overcome the mild resistance to anthracyclines, mitoxantrone, vincristine, thiopurines, epipodophyllotoxins and ifosfamide in childhood My+ ALL.

Treatment outcome and prognostic factors for infants with acute lymphoblastic leukemia treated on two consecutive trials of the Children's Cancer Group

PURPOSE

Infants represent a very poor risk group for acute lymphoblastic leukemia (ALL). We report treatment outcome for such patients treated with intensive therapy on consecutive Children's Cancer Group (CCG) protocols.

PATIENTS AND METHODS

Between 1984 and 1993, infants with newly diagnosed ALL were enrolled onto CCG-107 (n = 99) and CCG-1883 (n = 135) protocols. Postconsolidation therapy was more intensive on CCG-1883. On both studies, prophylactic treatment of the CNS included both high-dose systemic chemotherapy and intrathecal therapy, in contrast to whole-brain radiotherapy, which was used in earlier studies.

RESULTS

Most patients (>95%) achieved remission with induction therapy. The most frequent event was a marrow relapse (46 patients on CCG-107 and 66 patients on CCG- 1883). Four-year event-free survival was 33% (SE = 4.7%) on CCG-107 and 39% (SE = 4.2%) on CCG- 1883. Both studies represent an improvement compared with a 22% (SE = 5.1%) event-free survival for historical controls. Four-year cumulative probabilities of any marrow relapse or an isolated CNS relapse were, respectively, 49% (SE = 5%) and 9% (SE = 3%) on CCG-107 and 50% (SE = 5%) and 3% (SE = 2%) on CCG-1883, compared with 63% (SE = 6%) and 5% (SE = 3%) for the historical controls. Independent adverse prognostic factors were age less than 3 months, WBC count of more than 50,000/microL, CD10 negativity, slow response to induction therapy, and presence of the translocation t(4;11).

CONCLUSION

Outcome for infants on CCG-107 and CCG- 1883 improved, compared with historical controls. Marrow relapse remains the primary mode of failure. Isolated CNS relapse rates are low, indicating that intrathecal chemotherapy combined with very-high-dose systemic therapy provides adequate protection of the CNS. The overall unsatisfactory outcome observed for the infant ALL population warrants the future use of novel alternative therapies.

Expression of Myeloid Markers Lacks Prognostic Impact in Children Treated for Acute Lymphoblastic Leukemia: Italian Experience in AIEOP-ALL 88-91 Studies

The importance of coexpression of myeloid antigens in childhood acute lymphoblastic leukemia (ALL) has long been debated; results are conflicting. We studied children with ALL treated at Italian Association for Pediatric Hematology-Oncology (AIEOP) institutions over 6 years with Berlin-Frankfurt-Muenster (BFM)-based protocols and have analyzed the incidence of coexpression of six MyAg (CD11b, CD13, CD14, CD15, CD33, CD65w) to determine its prognostic impact. Criteria for MyAg coexpression (MyAg+ALL) included positivity to one or more MyAg on at least 20% of blasts and confirmation of coexpression at double-fluorescence analysis. A total of 291 of 908 cases were MyAg+ALL (32%). Incidence was similar in B-ALL and T-ALL; among common, pre-B, and pre-pre–B-ALL. CD13 and CD33 were most common. Patients with MyAg+ALL had presenting features similar to MyAg−ALL. They entered standard or intermediate risk protocols more frequently and had better prednisone response, but similar complete remission rates. Six-year event-free survival (EFS) was 69.0% in 291 MyAg+ALL cases and 65.3% in 617 MyAg−ALL cases, without significant difference. Cases expressing two or more MyAg presented similar clinical features and treatment response. MyAg+ALL had worse EFS only in infants (0% v47%) (P = .01). Therefore, in this series of homogeneously diagnosed and treated ALL, coexpression of MyAg was not associated with prognostic significance, without relevance for clinical purposes or for patient stratification, except for infants.

© 1998 by The American Society of Hematology.

Expression of Myeloid Markers Lacks Prognostic Impact in Children Treated for Acute Lymphoblastic Leukemia: Italian Experience in AIEOP-ALL 88-91 Studies

The importance of coexpression of myeloid antigens in childhood acute lymphoblastic leukemia (ALL) has long been debated; results are conflicting. We studied children with ALL treated at Italian Association for Pediatric Hematology-Oncology (AIEOP) institutions over 6 years with Berlin-Frankfurt-Muenster (BFM)-based protocols and have analyzed the incidence of coexpression of six MyAg (CD11b, CD13, CD14, CD15, CD33, CD65w) to determine its prognostic impact. Criteria for MyAg coexpression (MyAg+ALL) included positivity to one or more MyAg on at least 20% of blasts and confirmation of coexpression at double-fluorescence analysis. A total of 291 of 908 cases were MyAg+ALL (32%). Incidence was similar in B-ALL and T-ALL; among common, pre-B, and pre-pre–B-ALL. CD13 and CD33 were most common. Patients with MyAg+ALL had presenting features similar to MyAg−ALL. They entered standard or intermediate risk protocols more frequently and had better prednisone response, but similar complete remission rates. Six-year event-free survival (EFS) was 69.0% in 291 MyAg+ALL cases and 65.3% in 617 MyAg−ALL cases, without significant difference. Cases expressing two or more MyAg presented similar clinical features and treatment response. MyAg+ALL had worse EFS only in infants (0% v47%) (P = .01). Therefore, in this series of homogeneously diagnosed and treated ALL, coexpression of MyAg was not associated with prognostic significance, without relevance for clinical purposes or for patient stratification, except for infants.

© 1998 by The American Society of Hematology.

Primary blasts from infants with acute lymphoblastic leukemia cause overt leukemia in SCID mice

The establishment of an in vivo animal model system for infant acute lymphoblastic leukemia (ALL) would allow the testing of new agents against primary leukemic cells from infant ALL patients. We have demonstrated previously that growth of B-lineage leukemic cells in mice with severe combined immunodeficiency (SCID) was a significant prognostic factor for children with high risk ALL. We now have examined the significance of this prognostic variable for 13 infants with newly diagnosed ALL treated at participating institutions of the Children's Cancer Group (CCG). Chromosomal translocations were detected in 10/12 evaluated cases, including five with t(4;11), one each with t(7;9) and t(7;11), t(1;19), and t(9;22), and two with t(11;19). Twelve of the thirteen infants with ALL achieved remissions following induction chemotherapy. Primary leukemic cells from 8 of the 13 infants caused overt leukemia in SCID mice. Among these 8 SCID+ infants, 7 were CD10- and seven had cytogenetic or molecular evidence of an 11q23 rearrangement. Six of the 8 SCID+ infants have relapsed; only 2 remain in remission following chemotherapy or bone marrow transplant. However, among the 5 SCID- infants there were also two relapses. These data are suggestive of a poorer outcome for SCID+ infants, but larger numbers of patients must be analyzed to assess their statistical significance. In summary, we have established a SCID mouse model for human infant ALL that will be useful for 1) predicting short-term and long-term outcome of patients, 2) testing pharmacokinetics, efficacy, and toxicity of new agents, and 3) elucidating the in vivo mechanisms of chemotherapeutic drug resistance in infant ALL.

Myeloperoxidase gene expression in infant leukemia: a Pediatric Oncology Group Study

A high incidence of co-expression of myeloid-associated antigens in infant B-precursor Acute Lymphocytic Leukemia (B-ALL) has been reported, but the significance of this finding is uncertain. To further assess myeloid differentiation and its prognostic significance in this disease, we investigated the frequency of myeloperoxidase (MPO) gene expression in the blast cells from 43 infants with B-ALL registered in a Pediatric Oncology Group (POG) Pilot Study for Treatment of Infant ALL, utilizing a molecular probe for detection of MPO messenger RNA (mRNA) by Northern blot hybridization and a monoclonal antibody to detect MPO-protein by immunohistochemical staining. Sufficient RNA for Northern blot was extracted from 32 bone marrow or blood samples. In two cases, MPO mRNA was determined by a reverse transcriptase-polymerase chain reaction assay and was negative in both cases. MPO-specific transcripts (MPO+) were present in 19 of 34 (56%) samples analyzed. Immunoreactive MPO protein was positive in 13 of the 20 (65%) patients studied. No correlation was found between MPO gene expression and clinical or laboratory features, karyotypic patterns or clinical outcome. The high frequency of MPO gene expression demonstrated in this study suggests that leukemogenic events in many cases of infant B-ALL appear to involve a pluripotent stem cell not yet fully committed to lymphoid differentiation.

Heterogenous expression of CD15 in acute lymphoblastic leukemia: a study of ten anti-CD15 monoclonal antibodies in 158 patients

Discrepancies in the literature on acute leukemia blast cell immunophenotypes are sometimes related to differences between the epitopes recognized by various monoclonal antibodies (MoAb) in the same cluster of differentiation. CD15 is one example of such a variation. CD15 expression has been reported in 1.6% to 39% of acute lymphoblastic leukemias (ALL). We studied the expression of CD15 using 10 different commercially available anti-CD15 MoAbs and we observed three different expression patterns using anti-CD15 MoAbs by flow cytometry in 158 cases of ALL: Smy15c was found in 70% of B lineage ALLs, Smy15a and FMC-13 in 30 to 40% of cases and all others in less than 9% of B-ALL cases (p < 0.0001). In T lineage ALLs, Smy15c, Smy15a and FMC-10 identified CD15 in 30% of the cases and all others in less than 8% of the cases. Logistic regression revealed that Smy15a, CD34 and CD14 correlated significantly with Smy15c expression. We conclude that CD15 MoAbs have to be chosen carefully when ALL immunophenotype and subsequent studies of prognostic significance are performed particularly in assessing multiphenotypic ALLs.

[Neonatal acute leukemia: apropos of 7 cases]

BACKGROUND

Acute leukemia in neonates is rare and is more severe than leukemia in childhood.

POPULATION

Seven cases (four girls, three boys) were included in this series. Leukemia was diagnosed at birth in three cases; hepatosplenomegaly was seen in five cases and skin nodules in three. Hyperleukocytosis more than 100,000/mm3 was present in four cases; the WBC and differential counts were normal in two. A meningeal involvement was seen in one case. The leukemia was lymphoblastic (ALL) in three cases and myeloblastic (AML) in four. Intensive chemotherapy induced complete remission in five patients, persisting 5 and 4 years after the diagnosis in two. Classic risk factors such as high white blood counts, central nervous system involvement, myeloblastic lineage, absence of CALLA (common acute lymphoblastic leukemia antigen) expression and abnormal blast cell karyotype interesting the 11q23 area were found again in this series. Risk related to drug toxicities and infectious complications were also noted in this series of very young patients.

CONCLUSIONS

The outcome may depend on progress in pharmacology, search for new drugs and use of bone marrow transplantation.

Prognostic relevance of pretreatment proliferative rapidity of marrow blast cells in childhood acute lymphoblastic leukaemia

Cell proliferation rate is a well-established prognostic factor in cancer, but it has not been considered to identify the risk group of childhood acute lymphoblastic leukaemia (ALL) at presentation. We carried out a study to demonstrate the prognostic importance of the rapidity of cell proliferation in patients with ALL. To measure the rapidity of cell proliferation we used the parameter relative to the area of silver-stained nucleolar organiser regions (AgNORs) as evaluated by morphometric analysis on smeared marrow blast cells. The mean AgNOR area of leukaemic marrow cells was measured in 119 children. By using a cut-off value of 3 microns2, we identified a group of 91 children with low proliferating blast activity (mean AgNOR value 2.11 microns2) and a group of 28 children with high proliferating activity (mean AgNOR value 3.29 microns2). The group of patients with a mean AgNOR value > 3 microns2 was characterised by a higher number of deaths, more frequent relapse and shorter time interval to relapse than the group of patients with mean AgNOR value < 3 microns2 (P < 0.01). Multivariate analysis performed to include T-cell immunophenotype, FAB morphology, leucocyte count and presence of mediastinal mass showed that the mean AgNOR value was the only independent predictor of unfavourable event-free survival probability (P > 0.01). Our results indicate that the rapidity of marrow blast cell proliferation is an important prognostic parameter in childhood ALL and should be routinely introduced in the group risk definition.

Variable detection of myeloid antigens in childhood acute lymphoblastic leukaemia

AIMS

To determine whether the use of different sources of anti-CD13 and anti-CD33 monoclonal antibodies leads to discrepant results in childhood acute lymphoblastic leukaemia (ALL), which might contribute to the wide variation in the reported incidence of myeloid antigen expressing ALL in childhood.

METHODS

Stored leukaemic cells from 10 children with previously defined myeloid positive ALL were examined. A range of commercially available anti-CD13 and anti-CD33 monoclonal antibodies, directly conjugated with phycoerythrin or fluorescein isothyocyanate, or both, was used. Positively reacting cells were detected by flow cytometry.

RESULTS

There was a noticeable discordance between the different commercial sources of antibody and between the two fluorochromes in their ability to detect myeloid antigens, as well as variation in the intensity of staining. For CD13, one antibody reacted with eight cases and another with only four. Similarly, CD33 was detected in all 10 cases by one antibody and in only three by another.

CONCLUSIONS

The lack of any consistent pattern of results suggests that various commercial antibodies against the same CD antigen might recognise different epitopes and that the number of molecules per cell might vary from case to case. These observations partly explain the variation in reported incidence and the failure to establish the clinical importance of myeloid positivity, and they highlight the importance of standardisation in multicentre studies in which immunophenotypic data are collected.

The role of immunophenotype in acute lymphoblastic leukemia of infant age

The prognosis of acute lymphoblastic leukemia in infants is still significantly worse than that of older children. This is thought to be due to both clinical and biological factors, such as high white blood cell (WBC) counts at diagnosis, irregular or immature phenotypes, and molecular and cytogenetical abnormalities. In order to focus the significance of immunophenotypic analysis, we have reviewed the immunophenotypic studies of 145 infants under 18 months of age treated at the AIEOP centers from 1984 to 1992. Children have been divided in three age groups of six months each; WBC count at diagnosis has been evaluated both as mean values and within different categories (< 10.10(9)/L, > 100.10(9)/L). These have been studied in correlation with immunophenotype and with the expression of single, specific markers. A significant correlation has been found between young age, high WBC count and immature phenotypes. Common ALL was more frequent in older children and showed lower WBC counts. Moreover, event-free survival was significantly better in older children with WBC count < 100.00/mm3, with CD10+, MyAg- ALL. Therefore, we suggest that immunophenotypic analysis is still an important prognostic factor and can be usefully used, together with simple clinical data, to plan therapy for ALL in infants.

Improved survival for acute lymphoblastic leukaemia in infancy: the experience of EORTC-Childhood Leukaemia Cooperative Group

Out of 744 newly diagnosed ALL children under the age of 18 years treated according to the EORTC-CLCG protocols 58831 and 58832, 28 (4%) were infants less than 1 year of age. An elevated risk factor, which takes into account the sizes of the liver and spleen and the number of circulating blasts, was present in 25 cases. Most patients had non-common ALL. Among 15 patients studied by cytogenetics, nine present chromosomal abnormalities, six of them having a t(4;11) translocation. Complete remission was achieved in 86% of cases. One patient died in complete remission of therapy-related infection. The overall EFS is 43%. It is not statistically different in very young infants as compared to infants older than 6 months. Except for patients with AUL or with t(4;11) translocation, a continuous complete remission rate above 50% can be achieved with a median follow-up of 4 years. The results obtained in infant ALL with EORTC-CLCG protocols are currently better than those obtained with some other protocols, but remains inferior when compared to the ones obtained in older children. Thus, further improvements are needed and should be evaluated in large cooperative trials.

Possibilities and limitations of cytochemical methods in diagnosis of acute leukemia

Accurate identification and classification of leukemic blast cells is a very important prerequisite of the precise diagnosis of acute leukemia and has a great impact on therapy and prognosis. The purpose of this review is to consider, in the broad sense of the word, the present possibilities and limitations of enzyme cytochemistry and to emphasize how cytochemistry may contribute, on integration with the other methods of study, to the final classification and differential diagnosis of acute leukemia, a highly variable hematological disorder. In this review, the role of conventional enzyme cytochemistry, either dominant or subsidiary, in the discrimination of acute leukemia subtypes is discussed. The survey confirms the absolute necessity of immunologic marker analysis in the accurate diagnosis of acute lymphoblastic leukemia, undifferentiated or minimally differentiated leukemia and mixed-lineage leukemia because in these cases, the cytochemical evaluation provides insufficiently relevant information regarding blast cell origin, specificity of leukemia subtypes and the discrete stages of leukemic cell maturation. On the other hand, cytochemical investigation is appreciated to be dominant over immunophenotyping in characterizing acute myeloid leukemia, because of the lack of specificity of the majority of immunological markers against myeloid antigens and, because of the availability of standardized and sufficiently specific cytochemical reactions. The cytogenetic, molecular biological and electron microscopic studies mentioned in this review supplement the important information for correct differential diagnosis of acute leukemia. The prognostic impact of enzyme cytochemistry in correlation to other methods is evaluated.