Selective tropism of lymphadenopathy associated virus (LAV) for helper-inducer T lymphocytes.

Lymphadenopathy associated virus ( LAV ) has been isolated from patients with the acquired immunodeficiency syndrome (AIDS) or lymphadenopathy syndrome. Since the immune deficiency in AIDS seems to be primarily related to the defect of the helper-inducer T lymphocyte subset, the possibility that LAV is selectively tropic for this subset was investigated. Fractionation of T lymphocytes was achieved by cellular affinity chromatography with monoclonal antibodies. In a hemophilic patient who was a healthy carrier of LAV , reverse transcriptase activity and virus particles detected by electron microscopy were found only in cultures of helper-inducer lymphocytes. When infected with LAV in vitro, lymphocyte subsets from normal individuals yielded similar results. Virus production was associated with impaired proliferation, modulation of T3-T4 cell markers, and the appearance of cytopathic effects. The results provide evidence for the involvement of LAV in AIDS.

Predominant expression of circulating CD3+ lymphocytes bearing gamma T cell receptor in a prolonged immunodeficiency after allogeneic bone marrow transplantation.

The cell surface expression of alpha:beta heterodimer was studied using WT31 monoclonal antibody, in peripheral blood lymphocytes (PBL) from a patient who developed a prolonged immunodeficiency after allogeneic bone marrow transplantation. This patient, grafted for chronic myelogenous leukemia, received T cell depleted bone marrow from her HLA, A, B, D matched sibling. The late occurrence of opportunistic infection, led us to analyze the phenotype of patient PBL. 70% of PBL were CD3+ and 29% WT31+, indicating that the majority of CD3+ PBL did not express the alpha:beta heterodimer. Transcription of the genes encoding the alpha, beta, and gamma chains was assessed in cell lines derived from PBL, by Northern blot analysis. We showed that the CD3+ WT31- subset expressed a truncated, beta mRNA (1.0 kb) and also truncated alpha transcript (1.4 kb). To determine the CD3-associated structure on CD3+ WT31- cell line, immunoprecipitation assays were performed using monoclonal anti-CD3 and an hetero antiserum against gamma peptides. These CD3+ WT31- cells expressed a disulfide linked dimer, composed of products of gamma gene (37 kD, 40 kD) and of undefined delta chain (45 kD). Functional analyses were performed in PBL before and after sorting with WT31 and anti-CD3 antibody. These circulating CD3+ WT31- cells were unable to proliferate when triggered with anti-T3 beads and they seemed to mediate a suppressor activity on CD3+ WT31+ cells.

Cytotoxic T cell response against the chimeric ETV6-AML1 protein in childhood acute lymphoblastic leukemia.

Cytotoxic T lymphocytes (CTL) are potent effector cells that could provide long term antitumor immunity if induced by appropriate vaccines. CTL recognize 8-14 amino acid-long peptides processed intracellularly and presented by MHC class I molecules. A well-characterized example of a potential tumor antigen in childhood pre-B Acute Lymphoblastic Leukemia (ALL) results from the chromosomal translocation 12;21 leading to the fusion of the ETV6 and AML1 genes. This translocation is observed in > 25% of ALL-patients. In this study, we have examined whether the chimeric ETV6-AML1 protein could serve as a tumor specific antigen for CTL in HLA-A2.1 individuals. We have identified a nonapeptide (RIAECILGM), encoded by the fusion region of the ETV6-AML1 protein, that binds to HLA-A2.1 molecules and induces specific primary CTL in peripheral blood lymphocytes from healthy donors. These CTL specifically lysed HLA-A2.1 tumor cells endogeneously expressing the ETV6-AML fusion protein. CTL with similar functional capacities were found with high frequencies and cloned from one patient's bone marrow indicating that ETV6-AML1-specific anti-ALL CTL are, at least in some patients, spontaneously stimulated and might participate to host antileukemia defense.

No prognostic effect of additional chromosomal abnormalities in children with acute lymphoblastic leukemia and 11q23 abnormalities.

This study characterized the additional chromosomal abnormalities (ACA) associated with 11q23 rearrangements in 450 infants and children with acute lymphoblastic leukemia (ALL) and examined the impact of these ACA on survival. Overall, 213 (47%) cases had ACA but the incidence varied according to patient age and 11q23 subgroup. Infants and patients with t(4;11)(q21;q23) had the lowest incidence of ACA (50/182 (27%) and 57/216 (26%) respectively), whereas patients with del(11)(q23) had the highest incidence (66/93 (71%)). Del(11)(q23) abnormalities were heterogeneous and occasionally secondary to t(9;22)(q34;q11.2). Thus, patients with del(11)(q23) comprised a separate biological entity, which was clearly distinct from those with an 11q23 translocation. The most frequent specific ACA were trisomy X (n = 38), abnormal 12p (n = 32), abnormal 9p (n = 28) and del(6q) (n = 19). The presence of ACA did not change the 5 year event-free survival estimates among children (56% (95% Cl 46-65%) vs 62% (54-69%)) or infants (22% (15-29%) vs 18% (9-29%)), nor when the different 11q23 subgroups were analyzed separately. This study has conclusively demonstrated that there is no prognostic effect of secondary chromosomal changes in association with 11q23 abnormalities in childhood ALL. However, characterization of these ACA is important to determine their potential role in initiation of MLL driven leukemogenesis.

Value of intravenous 6-mercaptopurine during continuation treatment in childhood acute lymphoblastic leukemia and non-Hodgkin's lymphoma: final results of a randomized phase III trial (58881) of the EORTC CLG.

Between November 1990 and November 1996, EORTC Children Leukemia Group conducted a randomized trial in de novo acute lymphoblastic leukemia and lymphoblastic non-Hodgkin's lymphoma patients using a Berlin-Frankfurt-Munster protocol to evaluate the monthly addition of intravenous 6-mercaptopurine (i.v. 6-MP) (1 g/m(2)) to conventional continuation therapy comprising per oral MTX weekly and 6-MP daily. Only during the first 18 months of the randomization period, 6-MP p.o. was interrupted for 1 week after each i.v. 6-MP. A total of 877 patients was randomized to either no i.v. 6-MP (Arm A) or additional i.v. 6-MP (Arm B). A total of 217 relapses (91 in Group A vs 128 in Group B) and 13 deaths in CR (5 vs 8) were reported; a total of 134 patients (55 vs 79) died. The median follow-up was 7.6 years. At 8 years, the disease-free survival rate was lower (P=0.005) in Arm B (69.1% (s.e.=2.2%)) than in Arm A (77.9% (s.e.=2.0%)), and the hazard ratio was 1.45 (95% CI 1.12-1.89). In conclusion, as delivered in this study, i.v. 6-MP was detrimental to event-free survival.

Results of 58872 and 58921 trials in acute myeloblastic leukemia and relative value of chemotherapy vs allogeneic bone marrow transplantation in first complete remission: the EORTC Children Leukemia Group report.

The first EORTC (European Organization of Research and Treatment of Cancer) acute myeloblastic leukemia (AML) pilot study (58872) was conducted between January 1988 and December 1991. Out of 108 patients, 78% achieved complete remission (CR), and event-free survival (EFS) and survival rates (s.e., %) at 7 years were 40 (5) and 51% (6%), respectively. It indicated that mitoxantrone could be substituted for conventional anthracyclines in the treatment of childhood AML without inducing cardiotoxicity. The aim of the next EORTC 58921 trial was to compare the efficacy and toxicity of idarubicin vs mitoxantrone in initial chemotherapy courses, further therapy consisting of allogeneic bone marrow transplantation (alloBMT) in patients with an HLA-compatible sibling donor or chemotherapy in patients without a donor. Out of 177 patients, recruited between October 1992 and December 2002, 81% reached CR. Overall 7-year EFS and survival rates were 49 (4) and 62% (4%), respectively. Out of 145 patients who received the first intensification, 39 had a sibling donor. In patients with or without a donor, the 7-year disease-free survival (DFS) rate was 63 (8) and 57% (5%) and the 7-year survival rate was 78 (7) and 65% (5%), respectively. Patients with favorable, intermediate and unfavorable cytogenetic features had a 5-year EFS rate of 57, 45 and 45% and a 5-year survival rate of 89, 67 and 53%, respectively.

Bone marrow transplantation for chronic granulocytic leukemia.

Thirty-seven patients with chronic granulocytic leukemia have been treated with supralethal chemoradiotherapy followed by transplantation of bone marrow from HLA-identical donors. All patients showed engraftment, and the Philadelphia chromosome (PH1) disappeared in each case. Four patients had syngeneic grafts before blast crisis and are still alive; 2 are in remission not maintained by therapy, and 2 others are receiving chemotherapy after having relapsed in the chronic phase. Thirty-three patients had allogeneic grafts; only 2 received the grafts during blast crisis, and neither is a long-term survivor. Of the 13 patients who had grafts in the accelerated phase, 6 died of complications related to the transplantation, and 1 died after a myeloblastic relapse. Thus 6 patients are in unmaintained remission with a median follow-up of 13 months. Eighteen patients received grafts in the chronic phase. All 10 survivors are in unmaintained remission with a median follow-up of 14 months; in this group, no patient has relapsed. The granulocytic hyperplasia of the chronic phase can be more effectively ablated than established blastic leukemia. The mortality rate of transplant-related complications must be weighted against the typical rate of progression of chronic granulocytic leukemia. Although a longer follow-up period is needed for full evaluation, bone marrow transplantation may now be offered to patients in the chronic phase in an attempt to achieve long-term survival or cure of more than one-half of these patients.

Contribution of single-photon emission computed tomography in the diagnosis and follow-up of CNS toxicity of a cytarabine-containing regimen in pediatric leukemia.

PURPOSE: Cytarabine (ara-C) is one of the most effective chemotherapeutic agents in patients with acute leukemia (AL), with a clear dose effect. Use of high-dose ara-C is hampered, however, by a noticeable toxicity, particularly to the CNS. We investigated the usefulness of CNS perfusion imaging with technetium-99m ((99m)Tc)-hexamethyl-propylene-amine oxime (HMPAO) single-photon emission computed tomography (SPECT) concurrent to magnetic resonance imaging (MRI) to specifically assess the effects of standard- and high-dose ara-C in children with AL. PATIENTS AND METHODS: Twenty-six perfusion studies using (99m)Tc-HMPAO SPECT were performed in 12 children (age range, 4 to 15 years) with AL after induction therapy, which consisted of a standard-dose ara-C, immediately after consolidation with high-dose ara-C, and later during follow-up (range, 6 to 44 months). The chemotherapy-related adverse events were monitored and correlated to SPECT and MRI. RESULTS: After the induction phase, all children were neurologically normal on MRI. On SPECT imaging, four children displayed a slightly heterogeneous perfusion. After high-dose ara-C (4 to 36 g/m(2)), five children had regressive neurologic signs of potential toxic origin. Of these five children, only one had an abnormal MRI scan, whereas all patients showed evidence of diffuse cerebral and/or cerebellar heterogeneous perfusion on SPECT. The seven other patients without any neurologic symptoms had normal MRI scans; SPECT was normal for three patients and abnormal for four patients. On follow-up, for four children who had presented with clinical neurologic toxicity, SPECT improved in three patients and remained unchanged in one patients. In two of these four children, delayed abnormalities (T2 white matter hypersignal and cerebellar atrophy) appeared on MRI scans. CONCLUSION: In our series, diffuse heterogeneous brain hypoperfusion is often the sole early objective imaging feature identified by SPECT of high-dose ara-C neurotoxicity, where MRI still demonstrates normal pictures.

Outcome of childhood acute promyelocytic leukemia with all-trans-retinoic acid and chemotherapy.

PURPOSE: To determine the results of treatment combining all-trans-retinoic acid (ATRA) and chemotherapy (CT) in childhood acute promyelocytic leukemia (APL). PATIENTS AND METHODS: Children (< 18 years) with newly diagnosed APL were included in the APL93 trial, treated by ATRA followed or combined with daunorubicin-cytarabine, and then randomly assigned between no maintenance, intermittent ATRA, continuous CT, or both. RESULTS: Of the 576 patients included in APL93 trial, 31 (5%) were children, including 22 girls (71%) and nine boys (29%). Thirty of the children (97%) obtained complete remission (CR). ATRA syndrome occurred in four children (13%), who all achieved CR, and headaches occurred in 12 children (39%), with signs of pseudotumor cerebri in five children (16%). Seven patients (23%) relapsed. None of the eight patients who received both ATRA and CT for maintenance relapsed. All relapsing patients achieved a second CR. Twenty-two patients remained in first CR after 43+ to 96+ months, six remained in second CR after 17+ to 66+ months, and three patients had died. The 5-year event-free survival (EFS), relapse, and overall survival rates were 71%, 27%, and 90%, respectively. No difference between adults and children included in the APL93 trial was seen for CR rate, 5-year relapse rate, EFS, and overall survival, but significantly better survival was seen in children after adjustment on WBC counts (P =.02) and incidence of microgranular M3 variant (P =.04). CONCLUSION: ATRA combined with CT for induction and also probably for maintenance provides as favorable results in children with APL as in adults and currently constitutes the reference first-line treatment in both age groups.

Systemic effect of intrathecal methotrexate during the initial phase of treatment of childhood acute lymphoblastic leukemia. The European Organization for Research and Treatment of Cancer Children's Leukemia Cooperative Group.

PURPOSE: The in vivo response to prephase corticosteroid therapy for 1 week has been described as a major prognostic factor in childhood acute lymphoblastic leukemia (ALL). Patients with less than 1,000 blasts/microL at day 8 are considered responders and have a better prognosis. This prephase therapy is usually considered as an evaluation of glucocorticoid sensitivity. In fact, it also includes one intrathecal (IT) injection of methotrexate (MTX). In this study, we try to clarify the influence of this injection of IT MTX on the response to the prephase therapy. PATIENTS AND METHODS: This retrospective study analyzed the response to prephase therapy in 1,044 children with ALL entered onto the European Organization for Research and Treatment of Cancer (EORTC) trial 58881 of the Children's Leukemia Cooperative Group (CLCG). Analysis was restricted to 732 cases with an initial blast count greater than 1,000/microL. The following variables were tested to analyze response to prephase therapy: age, sex, evaluated risk factor (RF), blast count on day 0, actual dose of prednisolone administered, immunophenotype (T v non-T), and day of IT MTX. For statistical analysis, the variable day of IT MTX (D) was stratified into three groups: group 1 if D less than 2, group 2 if D > or = 2 but < or = 6, and group 3 if D greater than 6. RESULTS: All variables tested had a significant influence on response to the prephase therapy. This was especially true for IT MTX: 90.4% responders in group 1, 76.9% in group 2, and 70% in group 3 (P < .001). Immunophenotype was also a major predictor of response to the prephase: 88% responders in B-lineage ALL versus 56.2% in T-lineage ALL. IT MTX had a significant influence in B-lineage ALL (96% responders in group 1, 90% in group 2, and 79% in group 3; P < .001), whereas the influence could not be detected in T-lineage ALL. CONCLUSION: These results clearly demonstrate a therapeutic systemic effect of low doses of IT MTX in childhood ALL, and response to prephase therapy should not be considered as an in vivo test for cortico-sensitivity only. Earlier use of IT MTX leads to a higher percentage of responders.

Value of high-dose cytarabine during interval therapy of a Berlin-Frankfurt-Munster-based protocol in increased-risk children with acute lymphoblastic leukemia and lymphoblastic lymphoma: results of the European Organization for Research and Treatment of Cancer 58881 randomized phase III trial.

PURPOSE: The European Organization for Research and Treatment of Cancer 58881 study was designed to test in a prospective multicentric randomized trial the value of high-dose (HD) intravenous (IV) cytarabine (Ara-C) added to HD IV methotrexate (MTX) to reduce the incidence of CNS and systemic relapses in children with increased-risk acute lymphoblastic leukemia (ALL) or stage III and IV lymphoblastic lymphoma treated with a Berlin-Frankfurt-Munster (BFM)-based regimen. PATIENTS AND METHODS: After completion of induction-consolidation phase, children with increased-risk (risk factor > 0.8 or T-lineage) ALL or stage III and IV lymphoblastic lymphoma were randomized to receive four courses of HD MTX (5 g/m(2) over 24 hours every 2 weeks) and four intrathecal administrations of MTX (Arm A) or the same treatment schedule with additional HD IV Ara-C (1 g/m(2) in bolus injection 12 and 24 hours after the start of each MTX infusion) (Arm B). RESULTS: Between January 1990 and January 1996, 653 patients with ALL (593 patients) or lymphoblastic lymphoma (60 patients) were randomized: 323 were assigned to Arm A (without Ara-C) and 330 to Arm B (with Ara-C). A total of 190 events (177 relapses and 13 deaths without relapse) were reported, and the median follow up was 6.5 years (range, 2 to 10 years). The incidence rates of CNS relapse were similar in both arms whether isolated (5.6% and 3.3%, respectively) or combined (5.3% and 4.6%, respectively). The estimated 6-year disease-free survival (DFS) rate was similar (log-rank P =.67) in the two treatment groups: 70.4% (SE = 2.6%) in Arm A and 71.0% (SE = 2.5%) in Arm B. The 6-year DFS rate was similar for ALL and LL patients: 70.2% (SE = 1.9%) versus 76.3% (SE = 5.6%). CONCLUSION: Prevention of CNS relapse was satisfactorily achieved with HD IV MTX and intrathecal injections of MTX in children with increased-risk ALL or stage III and IV lymphoblastic lymphoma treated with our BFM-based treatment protocol in which cranial irradiation was omitted. Disappointingly, with the dose schedule used in this protocol, HD Ara-C added to HD MTX, although well tolerated, failed to further decrease the incidence of CNS relapse or to improve the overall DFS.

Listing of common HLA alleles and haplotypes based on the study of 356 families residing in the Paris, France, area: implications for unrelated hematopoietic stem cell donor selection.

In this study we have identified frequent human leukocyte antigen (HLA)-A, -B, -C,-DRB1, and -DQB1 alleles, frequent HLA-B/C, HLA-DRB1/DQB1 two-allele associations, and the most common HLA-A/B/C/DRB1/DQB1 five-locus haplotypes in a population residing in the Paris, France, area. The study was carried out in 356 families of children awaiting hematopoietic stem-cell transplantation (HSCT), with the selection criterion that haplotypes could be assigned with certainty to both the patient and at least one parent. Parental haplotypes were HLA-A, -B serologically typed, and HLA-C, -DRB1, -DQB1 broadly typed by polymerase chain reaction-sequence-specific oligonucleotide probe. The alleles of the most frequent haplotypes were subsequently defined at a high-resolution level by polymerase chain reaction-sequence-specific primer. The results on the distribution of common alleles and common allele associations demonstrated similarities with the previously published data in Caucasian populations, as expected from the geographic origin of the studied population. More importantly, this study provides the largest listing of common B/C and DRB1/DQB1 associations and of common five-allele haplotypes defined with certainty in a Caucasian population to date. These results can be used to help estimate the likelihood of finding a suitable donor in unrelated HSCT and to delineate search strategies for potential donors.

Late thyroid toxicity in 153 long-term survivors of allogeneic bone marrow transplantation for acute lymphoblastic leukaemia.

The purpose of this study was to identify risk factors for hypothyroidism after bone marrow transplantation (BMT) for high-risk or relapsed acute lymphoblastic leukaemia (ALL) in children. In all, 388 children with acute lymphoblastic leukaemia underwent allogeneic bone marrow transplantation between 1984 and 1994. Overall 5-year survival was 54.6%. Thyroid function was assessed in the 153 patients with more than 5 years of follow-up. In total, 16 patients developed uncompensated hypothyroidism (UH) and 46 compensated hypothyroidism (CH) a median of 2.9 and 2.7 years, respectively, after BMT. Thyroid dysfunction-free survival rates were 73.2% after 5 years and 59.2% after 10 years. Three factors were significantly associated with the onset of hypothyroidism, namely age, bone marrow transplantation in second remission, and single-dose total body irradiation (TBI). Ultrasonography of the thyroid showed nodules in 10 of 35 patients. The median time from BMT to nodule detection was 7.8 years. Cytology (n=5) and surgery (n=4) showed no evidence of thyroid cancer. Four of the 14 patients who received cytoreduction without TBI but with busulphan and cyclophosphamide developed UH (n=2) or CH (n=2). We concluded that children who undergo BMT for ALL are at a high risk of subsequent thyroid dysfunction.

A low rate of loss of heterozygosity is found at many different loci in childhood B-lineage acute lymphocytic leukemia.

We have carried out a screening for loss of heterozygosity (LOH) in 51 children with B-lineage acute lymphoblastic leukemia (ALL). Forty-six highly polymorphic microsatellite markers located in subtelomeric areas of every chromosome arm were analyzed in each patient. Allelic losses were encountered at 21 of the 46 loci tested (46%). The frequency of LOH at a given locus was usually < 10% and fractional allelic loss, calculated as the ratio of chromosomal arms displaying loss among all informative arms for each patient, ranged from 0.025 to 0.31 (mean, 0.063). This study provides further evidence that deletional events are a major type of genetic alteration found in childhood ALL. The diversity of the loci displaying LOH suggests that, as in solid tumors, numerous tumor suppressor genes are likely to participate in leukemogenesis. However, the overall low frequency of LOH, as well as the absence of microsatellite instability suggest that the genetic instability is lower in childhood ALL than in most of the solid tumors.

Delineation of a 6 cM commonly deleted region in childhood acute lymphoblastic leukemia on the 6q chromosomal arm.

Deletion of the long arm of human chromosome 6 in acute lymphoblastic leukemia (ALL) has been shown by cytogenetic studies in 4-11% of cases. To characterize further the region of deletion and to precisely establish its frequency, we studied loss of heterozygosity (LOH) in 120 children with ALL using polymorphic markers located from the 6q14-15 chromosomal band to the telomere. LOH was detected in eight patients. A single region of LOH, flanked distally by D6S1594 and proximally by D6S301 was detected. These DNA markers are separated by 6 cM and are approximately located at the 6q21-22 band. Our present results delineate a region that is likely to contain a tumor-suppressor gene involved in a subset of childhood ALLs.

High-resolution allelotype analysis of childhood B-lineage acute lymphoblastic leukemia.

Knowledge of the patterns of allelic loss has been useful in identifying tumor suppressor genes in many solid tumors. Although the loss of genetic material in acute lymphoblastic leukemias has been documented by cytogenetic studies and microsatellite typing, a global overview of losses of heterozygosity occurring throughout the genome was not yet available. We have performed a high resolution allelotype analysis in 63 childhood B-lineage acute lymphoblastic leukemia. A total of 247 microsatellite markers, evenly distributed along the autosomes were typed in blast and in remission samples from every patient. An average of 41 patients were informative for each marker. LOH at one or several loci was observed in 41 of the 63 patients (64%). The mean values for the fractional allelic loss (FAL) and the hemizygosity index, calculated for each patient, were 0.03 (range 0 to 0.23) and 0.024 (range 0 to 0.18), respectively. The most frequently involved chromosomal arms were 9p (36%), 12p (31%), 20q (15%), 6q (12%), 5p (10%) and 10p (10%). Three regions on chromosomal arms 9p, 12p and 6q were previously identified as the targets of recurring deletions, the target genes being identified for two of them (9p and 12p). The three new regions defined by this allelotype may contain tumor-suppressor genes implicated in the initiation or progression of childhood B-ALLs.

Mapping of chromosome 20 for loss of heterozygosity in childhood ALL reveals a 1,000-kb deletion in one patient.

The long arm of chromosome 20 displays recurrent loss of heterozygosity (LOH) for microsatellite markers in blast cells from children with acute lymphoblastic leukemia. To further characterize the region of deletion and to precisely establish its frequency, we searched for LOH in 103 children with ALL using polymorphic markers in the previously described region of interest, namely between D20S101 and D20S887. LOH was detected in nine patients (ie with a frequency of 8.7%). Interestingly, in one patient, a small deletion was found, flanked proximally by D20S850 and distally by M201, a dinucleotide repeat identified from chromosome 20 sequences. The distance between these two markers is approximately 1000 kb. The occurrence of non-random deletions of the long arm of chromosome 20 has previously been observed in myeloid malignancies (myeloproliferative disorders and myelodysplastic syndromes) in 5-10% of patients. The small deletion in our patient is located within the common region of deletion of myeloproliferative disorders suggesting that a tumor suppressor gene may be the common target of the deletions in various types of hematological malignancies.

Potential antileukemic effect of gamma delta T cells in acute lymphoblastic leukemia.

The immune response to leukemia is poorly understood. We postulated that nonmalignant T lymphocytes remaining within bone marrow from children with newly diagnosed ALL could be involved in this immune response. T lymphocytes which expressed gamma delta TCR comprised less than 1% of ALL marrow cells. A preferential outgrowth of gamma delta T cells within the CD3 population was observed when marrow cells were cultured with IL-2 alone or with stimulating feeder cells. These results, obtained in a series of 14 patients with precursor B-ALL, were significantly different when compared with expansions from normal marrow cells. In one patient, the clones established from the expanded population displayed different patterns of cytotoxicity against tumoral targets of the B cell lineage. Some clones expressing the TCR V delta 1 segment showed cytotoxic activity against a cell line derived from a pre-B ALL without activity against a LAK-sensitive B cell line. Using PCR amplification, one such clone was detected at high frequency, in the primary expansion of ALL marrow cells. These results suggest a prior activation in vivo of some gamma delta T cells by leukemic cells and provide some evidence on the role of these subsets in the immune response to leukemia.

Mitoxantrone and high dose Ara-C for the treatment of ANLL in childhood: a pilot study of the EORTC CLCG (EORTC 58 872).

Since January 1988, 91 children with ANLL have been treated with a polychemotherapy regimen containing Mitoxantrone (MTZ), excluding other anthracyclines. Induction consisted of Ara-C, MTZ, and VP 16. Consolidation lasted 6 weeks with Vincristine, MTZ, Ara-C and 6-thioguanine (6TG), and was followed by 2 intensification courses combining High-dose Ara-C with respectively MTZ or VP 16. Maintenance therapy associated 6TG, Ara-C and MTZ up to a cumulative dose of 150 mg/m2. 91 patients are evaluable: 70 (76.9%) achieved complete remission, 59 (64.8%) after induction alone. There were 7 early deaths, 5 deaths in complete remission, and 17 relapses. Major toxic side effects were observed during the consolidation phase, mainly infectious complications, and the median duration of neutropenia was 82 days in this phase, leading to decrease the MTZ dose from 10 to 8 mg/m2. The event-free survival at three years is 38%. Cardiac toxicity is presently absent in children without previous cardiopathy.

ETV6 is the target of chromosome 12p deletions in t(12;21) childhood acute lymphocytic leukemia.

The presence of ETV6 deletions was investigated in 215 children with acute lymphoblastic leukemia (ALL) using the loss of heterozygosity (LOH) approach. We used four intragenic or juxtagenic microsatellite markers to detect allelic deletions. In this series of unselected patients, LOH of ETV6 markers was found in 23% of cases (6% of T-ALL and 26% of B lineage ALL) confirming that chromosome 12p12-13 deletions represent a major genetic alteration in childhood ALL, frequently missed by cytogenetic analysis. The presence of a t(12;21)(p13;q22) was studied by RT-PCR and/or FISH in a total of 134 patients (125 B lineage ALL, nine T-ALL) including 42 cases with LOH. Thirty-four out of 44 patients (77%) for whom a t(12;21) was observed displayed LOH of the ETV6 markers. When associated with a t(12;21), ETV6 is very likely to be the target of deletions as indicated by the detection of intragenic deletions in three patients. Although deletion of ETV6 and t(12;21) were associated in most patients, in eight cases (six B lineage and two T-ALL) LOH was detected at the ETV6 locus without ETV6-AML1 hybrid RNA. FISH studies conducted in five of these eight patients confirmed the absence of translocation involving ETV6. In such patients, the other allele of ETV6 could be disrupted by either a small deletion, a point mutation, or an epigenetic modification and it will be of interest to study the structure and expression of the remaining allele of ETV6 in these cases. Alternatively, a tumor suppressor gene located close to ETV6 and CDKN1B could be the target of deletions.