Therapy-related myelodysplastic syndrome in childhood: A retrospective study of 36 patients in Japan

We report here a retrospective analysis of 36 children with therapy-related myelodysplastic syndrome (t-MDS) diagnosed between 1990 and 1999 in Japan. Their median age was 7.7 years and the median latency period for the development of t-MDS was 38.5 months. The primary tumors were hematologic in 15 of the cases and nonhematologic in 21. Chromosomal abnormalities were detected in 32/34(94%) patients: abnormalities of chromosomes 5and/or 7 in 41% and notably, 11q23 abnormalities in 31%. The prognosis of children with t-MDS was very poor as compared to children with primary MDS (5 year survival: 16% versus 54%, p<0.0001).

[Phase I study with irinotecan hydrochloride (CPT-11) for advanced neuroblastoma]

A Phase I trial of irinotecan hydrochloride (CPT-11) was performed to determine the maximum tolerated dose (MTD), the dose-limiting toxicities, and the incidence and severity of other toxicities in children with advanced neuroblastoma. Three children received 11 courses of CPT-11 administered as a 90-min i.v. infusion, daily for 3 days every 21 days. Doses ranged from 100 mg/m2 to 220 mg/m2. Two peaks in the total number of instances of diarrhea was observed, 25 stools at 3 days and 32 stools at 10 days. Myelosuppression was well controlled and of brief duration. One child achieved a clinical complete response (CR) and 2 had a partial response (PR). The MTD of CPT-11 administration was 180 mg/m2 for 3 days. These results indicate the usefulness of CPT-11 for the treatment of advanced neuroblastoma. Further investigation is necessary to establish its role in combination chemotherapeutic regimens.

Prognostic impact of CD45 antigen expression in high-risk, childhood B-cell precursor acute lymphoblastic leukemia

To evaluate the clinical implications of CD45 expression in acute childhood lymphoblastic leukemia (ALL), we measured the CD45 expression of blast cells from 133 untreated patients with childhood B-precursor ALL (n = 118) or T-ALL (n = 15). CD45 expression (> or = 20%) was detected in all 15 cases (100%) of T-ALL, and 101 cases (86%) of B-precursor ALL. In 122 cases, the fluorescence intensity of the CD45 expression was measured as a relative value; the ratio of average linear values (RALV) of CD45 on the blasts to that on CD3-positive T-lymphocytes from the same specimen. The expression was more intense in the T-ALL cases than in the B-precursor ALL cases (RALV, mean +/- SE: T-ALL 0.230 +/- 0.04 vs. pro-B ALL 0.150 +/- 0.012/pre-B ALL 0.153 +/- 0.019, p < 0.05). However, the intensity of the CD10, CD19, CD20 and CD34 antigen immunoreactivity did not correlate with the CD45 expression. Patients with hyperdiploidy (chromosome number > 50) showed significantly lower levels of CD45 expression than patients with t(1;19) or normal karyotypes (RALV, mean +/- SE: 0.081 +/- 0.022 vs. 0.133 +/- 0.03/0.143 +/- 0.019, p < 0.05). Other clinical features such as age, gender and WBC count did not correlate with CD45 expression. The prognostic implications of CD45 expression were studied in non-high-risk (low-risk + intermediate-risk) (n = 60) and high-risk patients (n = 52) with B-precursor ALL who had been treated with the risk-directed protocol of ALL-941 trial. Although CD45 expression did not correlate with the event-free survival (EFS) of the non-high-risk patients, there was a significant correlation between the expression levels and the EFS of the high-risk patients: the 3-year EFS rate of the CD45low group (n = 26, RALV = 0.017-0.132) was 88 +/- 7% versus the CD45high group (n = 26, RALV = 0.133-0.450) at 34 +/- 24% (p < 0.05). These results show that the levels of expression of the CD45 antigen on leukemic lymphoblasts are significantly correlated with the clinical features and prognosis of childhood ALL.

Mutations in the NMMHC-A gene cause autosomal dominant macrothrombocytopenia with leukocyte inclusions (May-Hegglin anomaly/Sebastian syndrome)

Macrothrombocytopenia with leukocyte inclusions is a rare autosomal dominant platelet disorder characterized by a triad of giant platelets, thrombocytopenia, and characteristic Döhle body-like leukocyte inclusions. A previous study mapped a locus for the disease on chromosome 22q12.3-q13.2 by genome-wide linkage analysis. In addition, the complete DNA sequence of human chromosome 22 allowed a positional candidate approach, and results here indicate that the gene encoding nonmuscle myosin heavy chain-A, NMMHC-A, is mutated in this disorder. Mutations were found in 6 of 7 Japanese families studied: 3 missense mutations, a nonsense mutation, and a one-base deletion resulting in a premature termination. Immunofluorescence studies revealed that NMMHC-A distribution in neutrophils appeared to mimic the inclusion bodies. These results provide evidence for the involvement of abnormal NMMHC-A in the formation of leukocyte inclusions and also in platelet morphogenesis.

[Treatment and prognosis of children with relapsed non-Hodgkin's lymphoma--a report from CCLSG-NHL 890 Study. Children's Cancer and Leukemia Study Group (CCLSG)]

To address the issue of salvageability in relapsed children with NHL who had all received the same frontline therapy, we retrospectively studied the treatment response and the outcome of 27 children who relapsed following the CCLSG-NHL890 protocol. The reinduction rates and 3-year survival rates (mean +/- SD) were as follows: lymphoblastic lymphoma (LB, n = 9), 44% & 17 +/- 14%; leukemia lymphoma syndrome (LLS, n = 8), 25% & 0%; large cell lymphoma (LC, n = 3) 100% & 67 +/- 27%; Burkitt's lymphoma (B, n = 7) 0% & 0%. Thus, the salvageability of LC lymphoma was good, but the outcome of Burkitt's lymphoma was very poor. CCLSG-NHL960 protocol for LB lymphomas and intensive multiagent regimens for LC lymphomas produced favorable response rates, but the effect of the high-dose Ara-C regimen for Burkitt's lymphoma was not determined. The initial stages of the disease seemed to be associated with the patient outcome: the outcome of the patients in stage IV was inferior to that of patients in stages II or III. Other clinical variables, such as relapse sites, relapse time and BM rescue did not affect the patients' outcome.

[Non-Hodgkin's lymphoma: treatment and outcome of children with advanced disease]

In recent years, the results of treating children with advanced non-Hodgkin's lymphomas have improved markedly. Among patients with small non-cleaved cell lymphoma (both Burkitt's and Burkitt-like lymphomas according to the Revised European American Lymphoma Classification) in particular, about 80% could be cured by a short intensive polychemotherapy containing cyclophosphamide, high-dose methotrexate, and high-dose cytarabine. In contrast, standard treatment strategies for the diffuse large cell lymphomas and lymphoblastic lymphomas have yet to be established. Recent studies have shown that the treatment protocols for patients with large cell lymphomas should be determined based on both the histological and immunological classifications. Since the outcome of lymphoblastic lymphoma patients who are treated with a multi-drug regimen is less than optimal, further improvement in this therapy is needed. At the present time, the combination of bone marrow rescue with high-dose therapy is partially effective for refractory cases. To further help these patients, new strategies with allogenic stem cell transplantation to further boost the potential graft-versus-lymphoma effect appear necessary.

The first Japanese family with Sebastian platelet syndrome

This report describes the first Japanese family diagnosed with Sebastian platelet syndrome. Within this family, a 6-year-old boy and 3 family members on his paternal side demonstrated thrombocytopenia with giant platelets and inclusion bodies in granulocytes, but the additional clinical features of Alport's syndrome occurring in the Fechtner syndrome were lacking. Light microscopy and ultrastructural findings of the leukocyte inclusion bodies distinguished these patients from the May-Hegglin anomaly. This family showed consistently higher levels of platelet-associated IgG (PAIgG), while surface expression of platelet membrane glycoproteins (GPIIb/IIIa and GPIb) and plasma glycocalicin levels were within the normal range. Careful observation of the giant platelet and leukocyte inclusion bodies in blood smears may help the diagnosis of this rare disease entity.

[The role of mitochondria in apoptosis in U937 and Molt-4 cells: difference in order of mitochondrial membrane potential (delta psi m) reduction and interleukin-1 beta-converting enzyme (ICE) on signal transduction pathway in each cell type]

Time-course-analysis of two apoptotic events of DNA fragmentation and delta psi m reduction revealed that delta psi m reduction preceded DNA fragmentation in U937 and Molt-4 cells treated with etoposide (ETP). DNA fragmentation and delta psi m reduction were inhibited by N-acetylcysteine (NAC) in both cell lines treated with ETP. These findings suggest that DNA fragmentation was inhibited through maintenance of delta psi m. Z-Asp-CH2-DCB, interleukin-1 beta-converting enzyme (ICE) specific inhibitor, inhibited ETP-induced DNA fragmentation and delta psi m reduction in U937 cells. This suggests that activation of ICE is an earlier event than delta psi m reduction. On the other hand, in Molt-4 cells, Z-Asp-CH2-DCB inhibited ETP-induced DNA fragmentation but not delta psi m reduction, suggesting that delta psi m reduction occurs earlier than activation of ICE.

Improvement in CNS protective treatment in non-high-risk childhood acute lymphoblastic leukemia: report from the Japanese Children's Cancer and Leukemia Study Group

BACKGROUND

Prevention of central nervous system (CNS) leukemia by early introduction of therapy to this sanctuary site is an essential component of modern treatment strategy for acute lymphoblastic leukemia (ALL). However, the optimal form of preventive CNS therapy remains debatable.

PROCEDURE

To address this issue, we evaluated the efficacy of CNS preventive therapy for 572 children with ALL who achieved complete remission in the Children's Cancer and Leukemia Study Group (CCLSG) ALL874 (1987-1990) and ALL911 (1991-1993) studies. They received risk-directed therapy based on age and leukocyte count. In the ALL 874 study, the non-high-risk (low-risk [LR] + intermediate risk [IR]) patients were randomly assigned to the conventional cranial irradiation (CRT) regimen (L874A and I874A) and the high-dose methotrexate (HDMTX) regimen without CRT (L874B and I874B). The former patients received 18-Gy CRT plus 3 doses of intrathecal (i.t.) MTX and the latter patients received 3 courses of HDMTX at 2 g/m2 plus 13 doses of ITMTX (L874B) or 4 courses of HDMTX at 4.5 g/m2 plus 1 dose of ITMTX (I874B).

RESULTS

The 7-year probabilities (+/- SE) of CNS relapse-free survival were 97.3% +/- 2.6% (L874A, n = 41) vs. 90.3% +/- 5.3% (L874B, n = 39) (P = 0.25) in the LR patients, and 100% (I874A, n = 55) vs. 78.5% +/- 6.5% (I874B, n = 54) (P = 0.002) in the IR patients. The corresponding disease-free survival (DFS) rates were 79.4% +/- 6.5% vs. 74.4% +/- 7.3% (P = 0.62) in the LR group and 63.3% +/- 6.8% vs. 58.3% +/- 7.2% (P = 0.66) in the IR group. Thus, the HDMTX regimen could not provide better protection of CNS relapse as compared with the CRT regimen, although their overall efficacy was not significantly different. In the ALL 911 study, intensive systemic chemotherapy with extended i,t, injections of MTX plus cytarabine achieved a high CNS relapse-free survival (98% +/- 1.9% at 7 years) and a favorable DFS (85.5% +/- 5% at 7 years) in the IR patients. The patients in the high-risk (HR) group in both ALL874 and ALL911 studies received the 18-Gy or 24-Gy CRT with intensive systemic chemotherapy. Their 7-year probabilities of CNS relapse-free survival ranged from 88% to 95%, among which the T-ALL patients had a risk of CNS leukemia, which was 3-4 times higher compared with B-precursor ALL patients.

CONCLUSIONS

These results indicate that long-term intrathecal CNS prophylaxis as well as appropriate systemic therapy for the non-high-risk patients can provide protection against CNS relapse equivalent to that provided by cranial irradiation.

[Studies of childhood non-Hodgkin's lymphoma--treatment results with the CCLSG NHL 960 protocol. Children's Cancer and Leukemia Study Group (CCLSG)]

We report here on the preliminary treatment findings of a CCLSG NHL 960 study that was initiated in March 1996. In this study, 37 patients with non-Hodgkin's lymphoma were assigned to 4 different treatment groups according to disease stage and histology: (1) localized disease; (2) advanced disease, lymphoblastic type; (3) advanced disease, large cell type; and (4) advanced disease, Burkitt type. The first three groups received the modified protocols of the NHL 890 study. Groups 1 and 3 received COPADM induction therapy (CPM, VCR, PRD, ADR, and MTX). After achieving remission, Group 1 received only maintenance therapy consisting of alternate administration of 7 drugs, while Group 3 received additional intensification therapy with combination chemotherapy consisting of MTX and Ara-C, followed by a maintenance phase involving the administration of 9 drugs. Group 2 received COPADL induction therapy (CPM, VCR, PRD, ADR, and LASP) and consolidation/intensification therapies followed by a maintenance phase. Group 4 received short-term intensive COPADM polychemotherapy. Twelve patients with localized with localized disease (stage I-II) and 25 patients with advanced disease (stage III-IV) were enrolled in this study. Except for 2 patients in the advanced disease stages who died earlier in the course of the study, all patients remained in remission.

[Bone marrow relapse in high-risk pediatric patients with acute lymphoblastic leukemia: a comparison of relapse times and initial clinical features of patients on different protocols. Children's Cancer and Leukemia Study group (CCLSG)]

To clarify the efficacy of modern intensive chemotherapy for ALL patients with unfavorable features, we compared the time to failure and initial clinical features of children who relapsed in the bone marrow or combined sites, as documented by early CCLSG studies (H811 and H851; 1981-1987) and later studies (H874 and H/HH911; 1987-1993) concerning high-risk ALL patients. In the later studies patients outcomes with new intensive regimens employing early intensification and reinduction therapy were apparently better than those of patients in the early studies with conventional regimens. When we compared the number of relapsed patients based on duration of first remission, we found that the improved outcomes for patients in the later studies were due to a decrease in the number who relapsed 7-36 months after the start of treatment (intermediate relapse), and that the percentage of those who relapsed within the first 6 months of therapy (early relapse) was higher. Patients with high initial WBC counts tended to relapse much earlier than those with low initial WBC counts. However, in the later studies, patients with high WBC counts often relapsed after the termination of therapy (late relapse). These results suggest that the intensive chemotherapy regimens used in the later studies can prevent the development of drug resistant leukemic clones, except in extremely high-risk patients likely to relapse within the first 6 months of therapy.

[Treatment of children with non-Hodgkin's lymphoma with CCLSG NHL 855/890 protocols long-term outcome and incidence of secondary malignancies]

We report here on treatment results of consecutive CCLSG NHL studies (NHL855, 1985-1989; NHL890, 1989-1996). The NHL855 protocol consisted of an induction phase of five drugs (VCR, PRD, CPM, DXR, and high-dose MTX) and a maintenance phase of 7 drugs. The probabilities of EFS at 7 years were 78% (SE, 10%) for the patients with localized disease, and 38% (SE, 7%) for those with advanced disease. In the NHL 890 protocol, the patients were assigned to two different treatment groups according to their histology and received different consolidation therapy; non-lymphoblastic subtype was treated almost identically to NHL855 while LASP and VP-16 were newly added for the lymphoblastic subtype. The 7-year EFS improved to 91% (SE, 6%) for localized disease, and 61% (SE, 6%) for advanced disease. A remarkable improvement was particularly evident for lymphoblastic type with mediastinal mass. Optional trial of high-dose sequential chemotherapy and peripheral blood progenitor cell auto grafting resulted in an unfavorable outcome. The 7-year EFS according to main histological subgroups were as follows: 84% (10%) for large cell type, 67% (11%) for Burkitt's-type, 58% (10%) for lymphoblastic type. Secondary cancer occurred in two of the 163 patients studied. Both patients were AML (M0/M4) and MLL rearrangement was detected in the M4 case.

Bcl-2 expression and prognosis in childhood acute leukemia. Children's Cancer and Leukemia Study Group

Bcl-2 expression and its prognostic value were evaluated in 42 children with acute leukemia. The Bcl-2 expression of the leukemic blast cells was measured quantitatively by flow cytometry and was further analyzed by the simultaneous immunostaining of Bcl-2 with the surface membrane antigens, DNA, Ki-67 antigen. All of the cases showed a consistent expression of Bcl-2 protein; virtually all leukemic lymphoblasts were Bcl-2 positive. Although the expression of Bcl-2 varied widely from 7 to 80 x 10(3) MESF units, no significant difference was found in the mean value between the patients with acute lymphoblastic leukemia and those with acute myeloblastic leukemia. In more than half of the patients with AML, intraclonal heterogeneity of Bcl-2 expression was observed. The expression of Bcl-2 showed no apparent fluctuations during the different phases of the cell cycle. However, the proportion of Bcl-2-positive and -negative cells during the cell cycle was different between ALL and AML patients. In the ALL patients, few Bcl-2-negative cells were detected only in the GI phase, whereas in the AML patients Bcl-2-negative cells were detected in the S and G2/M phases, as well as in the G1 phase. No apparent difference was found in Bcl-2 expression between the Ki-67-negative noncycling population and the Ki-67-positive cycling population. Of the clinical features of these patients, only CD34 expression in the ALL patients was associated with high levels of Bcl-2 expression. In the 28 untreated cases of ALL, high expression of Bcl-2 was not an unfavorable factor for the outcome of this disease.

[Pharmacokinetic studies of all-trans retinoic acid (ATRA) and pilot study of intermittent schedule of ATRA and chemotherapy in childhood acute promyelocytic leukemia. Children's Cancer and Leukemia Study Group]

A pharmacokinetic study of all-trans retinoic acid (ATRA) was performed in 8 patients with various types of leukemia and MDS. After oral administration at a dose of 30 mg/m2, the mean peak plasma concentration was 430 ng/ml and was reached at 150 min. In one patient who failed to respond a very low plasma ATRA level was seen. Though the plasma ATRA exposure decreased significantly with daily drug administration, an intermittent schedule of ATRA administration would yield higher plasma drug concentrations. We treated 2 patients with refractory acute promyelocytic leukemia (APL) in a pilot study of ATRA followed by intensive chemotherapy (APL-ATRA protocol). Two patients successfully achieved complete remission with ATRA after failing under conventional chemotherapy. Based on the pharmacokinetic study of ATRA, an intermittent schedule of ATRA in addition to chemotherapy suggests an effective regimen for children with APL. Phase II trials to evaluate the role of intermittent schedules of ATRA are planned in Children's Cancer and Leukemia Study Group.

[Cytogenetic abnormality and prognosis in childhood acute myeloblastic leukemia. Children's Cancer and Leukemia Study Group (CCLSG)]

We report on the leukemic cell karyotype of 180 children with acute myeloblastic leukemia (AML). They were treated by the protocols of chemotherapy for the Children's Cancer and Leukemia Study Group (CCLSG) in the last decade. Of 132 cases with adequate banding analysis, 24.2% had normal karyotype, 21.2% had miscellaneous clonal abnormalities and 54.6% were classified into known cytogenetic subgroups: t(8;21) (n = 35), t(15;17) (n = 23), inv (16) (n = 6), t(11q23;V) (n = 6), -7/7q-(n = 2). Each karyotype was closely correlated with a particular FAB subtype such as t(8;21) in M2, t(15;17) in M3, inv (16) in M4, t(11q23;V) in M5. In the M1+M2 group, although patients with t(8;21) had favorable clinical features such as low WBC counts and less frequent lymphadenopathy, their treatment outcome was not significantly better than those of patients with a normal karyotype (3-year EFS: 58 +/- 11% vs. 47 +/- 12%). Patients with miscellaneous chromosomal abnormalities had a significantly shorter EFS (22% +/- 10%) (p < 0.05) than those with t(8;21) or normal karyotype. In M4+M5 group, 2-year EFS of patients with inv (16) (40 + 30%) was longer than that of patients with normal karyotype (25 +/- 19%), and t(11q23;V) or miscellaneous chromosomal abnormalities (0 +/- 25%). These results suggest that cytogenetic data may be useful for risk-based treatment assignments for children with AML.

[Prognostic implication of DNA contents on long-term outcome of childhood acute lymphoblastic leukemia]

Prognostic value of cellular DNA content was evaluated in 189 children with acute lymphoblastic leukemia. Treatment outcome of the three different DNA index (DI) groups (Group A, DI = 1.0 vs. Group B, DI 1.01-1.15 vs. Group C, DI > or = 1.16) was compared between the two treatment risk groups (standard-risk and high-risk groups) stratified by the initial leukocyte count and age. In the standard-risk group, these groups had 10-year event free survival (EFS) rate (SE) of 62% (6%), 40% (21%) and 87% (6%), respectively (p < 0.05). In the high risk group, they had 10-year EFS rate of 30% (5%), 33% (27%) and 60% (19%), respectively (p < 0.01). Use of the DI, leukocyte count and age may be sufficient to distinguish the patients with an extremely low risk of failing to the standard ALL therapy from the patients with a relatively high-risk of treatment failure.

Differential induction of apoptosis on human lymphoblastic leukemia Nalm-6 and Molt-4 cells by various antitumor drugs

To investigate how chemotherapy agents interact with the leukemic cell death pathway, we examined apoptosis of human lymphoblastic leukemia cells (Nalm-6 and Molt-4) treated with various anticancer drugs (etoposide (VP-16), camptothecin (CPT), adriamycin (ADR), cytosine arabinoside (Ara-C), methotrexate (MTX), 6 mercaptopurine (6MP), cyclophosphamide (CPM), vincristine (VCR) and prednisolone (PRD)) by flow cytometric procedures. The proportion of apoptotic cells was estimated from the presence of cells with a fractional DNA content in the DNA histograms after the incubation of drug-treated cells with a DNA extraction buffer. Treatment with Ara-C, CPT, VP-16 and ADR resulted in rapid apoptosis with 40-60% apoptotic cells by 8 h. Treatment with MTX, VCR, 6MP and PRD induced no apparent apoptosis until 12 h, but further treatments with these drugs resulted in apoptosis with 50% (MTX), 20-30% (6MP and VCR) and 5-10% (PRD) apoptotic cells, respectively, at 24 h. CPM induced apoptosis with 10-20% apoptotic cells at 10(-6) M, but higher doses (> 10(-5) M) caused a rapid cell death by necrosis. The cell cycle position of apoptotic cells was assessed by the terminal deoxynucleotidyl transferase (TdT) assay of DNA strand breaks combined with DNA staining. MTX, Ara-C, CPT, VP-16 and ADR preferentially induced apoptosis in the S phase. PRD and 6MP induced apoptosis in the G1 phase and G1 + S phases, respectively. CPM showed no cell cycle phase specificity. These findings suggested that the susceptibility of cells to apoptosis was not the sole determinant of cellular sensitivity of cytotoxic drugs.

Treatment outcome and prognostic factors in childhood acute myeloblastic leukemia: a report from the Japanese Children's Cancer and Leukemia Study Group (CCLSG)

Treatment outcome and prognostic factors were evaluated in 152 children with acute myeloblastic leukemia (AML) treated on three consecutive protocols (ANLL 861, 8912, 9205) of the Children's Cancer Leukemia Study Group (CCLSG, Japan). In the ANLL 9205 protocol, anthracycline was used with a continuous infusion of cytosine arabinoside, followed by an intensive sequential post remission chemotherapy of short duration. Forty-two of these 46 patients (91.3%) achieved complete remission, and 58.8% of these patients projected a 3-year disease-free survival. These results were apparently superior to those obtained with the ANLL 861 and 8912 protocols, which used conventional doses of multiple drugs followed by a moderate post remission chemotherapy of long duration. This favorable response with the ANLL 9205 protocol was attributed mainly to the high induction rate of patients with the M4 and M5 FAB subtypes, as compared to those in the previous two protocols (93.3% in ANLL 9205 vs. 57.9% in ANLL 861 + 8912; P < 0.05). The ANLL 861 and 8912 protocols, an older age (> or = 8 years), higher WBC counts (> or = 10 x 10(9)/1) and all predicted an increased risk of relapse and decreased the survival following univariate analysis (P < 0.05). An older age and high WBC count continued to predict an increased risk of relapse in multivariate analyses: patients with an age > 8 years and WBC counts > 10 x 10(9)/1 had a 4.5 times higher risk of relapse than patients without these adverse features.

[Treatment results in childhood acute myeloblastic leukemia--a report of clinical trials of a past decade from the Japanese children's Cancer and Leukemia Study Group (CCLSG)]

Treatment results were evaluated in 167 children with acute myeloblastic leukemia (AML) treated on four protocols (ANLL 861, 8912, 9205, APL-ATRA) of the Children's Cancer Leukemia Study Group. In the ANLL 9205 protocol, anthracycline was used with a continuous infusion of cytosine arabinoside, followed by an intensive sequential post remission chemotherapy of short duration, 42/46 patients (91.3%) achieved complete remission, and 58.8% of these patients projected a 3-year disease free survival. These results were apparently superior to those obtained with the ANLL 861 & 8912 protocols, which used conventional doses of multi drugs followed by a moderate post remission chemotherapy of long duration. This favorable response with the ANLL 9205 protocol was attributed mainly to the high induction rate of patients with the M4 and M5 FAB subtypes, as compared to those in the previous two protocols (91.3% in ANLL 9205 vs 57.9% in ANLL 861 + 8912; p < 0.05). No significant difference in the patients outcome was found between the chemotherapy group and allogenic bone marrow transplantation group in the ANLL 9205 study. The patients with the M3 FAB subtype treated with the APL-ATRA protocol which consisted of an alternative use of all-trans retinoic acid and chemotherapy significantly prolonged event free survival as compared with the patients treated with ANLL 861/8912 protocols without all-trans retinoic acid.

Cell cycle kinetics in childhood acute leukemia studied with in vitro bromodeoxyuridine labeling, Ki67-reactivity, and flow cytometry

Cell cycle kinetics of childhood acute leukemia were determined by the in vitro labeling of marrow blast cells with bromodeoxyuridine (BrdUrd) and subsequent flow cytometry of BrdUrd/DNA and Ki67/DNA in 18 patients with acute lymphocytic leukemia (ALL) and eight patients with acute nonlymphocytic leukemia (ANLL). The BrdUrd-labeling index (BrdUrd-LI) and the duration of S phase (Ts) were calculated from the slope of the regression line obtained by plotting the serial labeling indices against the labeling time. The Ts and potential doubling time (DTpot) of marrow leukemia cells varied from 6.1 to 34.3 h (median 14.3 h) and 1.1 to 20.7 days (median, 7.3 days), respectively. The duration of the total cell cycle time (Tc) which was determined by the Ki-67-derived growth fraction (Ki-67-GF) varied from 14.0 to 112.5 h (median 43.2 h). BrdUrd-LI, DTpot, Ki-67-GF and Tc were significantly correlated with the subtypes (early B-ALL, T/B- ALL and ANLL) of the disease. The median values of LI and GF were much lower in ANLL than in ALL. However, the low proliferative activity of ANLL was not accompanied by a prolonged duration of the total cell cycle time. The longest median duration of Tc was noted in early B-ALL (75.2 h) and the median Tc in ANLL (36.7 h) was close to that in T/B-ALL (34 h). Ts appeared to be rather independent of subtypes of the disease. These results show that there are distinct in vitro growth characteristics in relation to the subtypes of childhood acute leukemia.

[Expression of a proliferation associated-nuclear antigen defined by Ki-67 monoclonal antibody in childhood acute leukemia]

The growth fraction of childhood acute leukemia was evaluated by the immunostaining with the monoclonal antibody "Ki-67", which reacts with a nuclear antigen in proliferating cells. Ki-67 labeling rates (the percentage of Ki-67 positive cells in the total cells analyzed) greatly varied from patient to patient (0.0% approximately 49.2%). The mean value of the Ki-67 labeling rates was significantly higher in ALL than in ANLL (23.6% vs 5.6%, p < 0.001). In ALL, the Ki-67 labeling rates correlated with the proportion of S-phase cells determined by DNA flow cytometry (FCM) (r = 0.82) High Ki-67 labeling rates were preferably seen in ALL with favorable prognostic factors, although the correlation was not statistically significant. These results suggest that Ki-67 labeling rates reflect the differences in proliferative activity of bone marrow blast cells in childhood acute leukemia and is useful to determine the treatment schedule of cycle specific drugs.

Cell cycle progression and phenotypic modification of Ki67 antigen-negative G1- and G2-phase cells in phorbol ester-treated Molt-4 human leukemia cells

To elucidate the relationship between the level of cellular Ki67-reactive antigen and cell proliferation, the effects of 12-O-tetra-decanoylphorbol 13-acetate (TPA) on Ki67 expression, cell cycle progression, and surface phenotypes of human T-lymphoblastic leukemia Molt-4 cells were investigated by multiparameter flow cytometry. The Ki67 antigen is constitutionally expressed in almost all untreated exponentially proliferating Molt-4 cells. Treatment with 10 nM TPA prolonged the duration of the cell cycle time and resulted in a progression arrest of cells in G1- and G2-phases, during which Ki67 expression was decreased to an undetectable level. However, in TPA-treated cultures, the Ki67-positive fraction was invariably smaller than the growth fraction as estimated from continuous 5-bromodeoxyuridine (BrdUrd) labeling curves. This discrepancy could be explained by the finding that some Ki67-negative G1 cells do not enter the resting state but instead remain in the cycling compartment. These results show that Ki67 expression of tumor cells with relatively long G1 duration is downregulated to undetectable levels in late G1-phase and the difference in the level of Ki67 expression between late G1 cells and resting G1 cells is undetectable by conventional immunological methods. Although TPA induced differentiation of Molt-4 cells into mature suppressor T cells, the phenotypic modification was not correlated with cell cycle position and Ki67 reactivity of the cells. These results suggest that growth arrest and phenotypic differentiation of Molt-4 cells are independent effects of TPA.

Cell-cycle-associated expressions of proliferating cell nuclear antigen and Ki-67 reactive antigen of bone marrow blast cells in childhood acute leukemia

To investigate the growth characteristics of human leukemia cells, the expression of proliferation-associated nuclear antigens was examined in relation to cell cycle phases in marrow blast cells obtained from 37 untreated children with acute leukemia. Ki-67 monoclonal antibody reactive antigen and proliferating cell nuclear antigen (PCNA) were measured by the simultaneous flow cytometric analysis of DNA and nuclear antigens. The percentage of PCNA-positive cells was always higher than that of Ki-67-positive cells in individual patients. The level of PCNA was greatly increased in G1 or early S phase, but was generally stable in S and G2 phases. Accordingly, most of the cells in the proliferative compartments (greater than 2C DNA) showed a high expression of PCNA. In contrast, expression of Ki-67 antigen varied greatly from patient to patient, and differed significantly in different subtypes of the disease. The level of Ki-67 antigen increased with the cell cycle progression, showing maximum expression in late S and G2 phases. However, in most of the patients, a distinct population of Ki-67-negative cells was found not only in G1 phase, but also in the proliferative compartments. These results appear to reflect differences in the proliferative activity of bone marrow blast cells in childhood acute leukemia.

[Flow cytometric measurement of cell surface and intracellular antigens present in leukemia cells]

Recent advances in flow cytometric technology has enabled us to perform multiparameter analysis of cell surface and intracellular antigens. The clinical application of such analyses requires to establish the procedures of sample preparation, fixation, staining, instrument calibration and data analysis. This article describes the basic elements involved in establishing such procedures and explores the use of multiparameter flow cytometric analysis in the characterization of human leukemia cells. Flow cytometric measurements of cell surface and intracellular antigens of leukemia cells can provide important insights into the biologic features of these cells as well as significant diagnostic information.

Cell proliferation in childhood acute leukemia. Comparison of Ki-67 and proliferating cell nuclear antigen immunocytochemical and DNA flow cytometric analysis

The proliferative activity of bone marrow leukemia cells was determined by DNA flow cytometric (FCM) analysis and labeling index (LI) of Ki-67 monoclonal antibodies and proliferating cell nuclear antigen (PCNA) autoantibodies in 73 children with acute leukemia. LI of Ki-67 varied greatly from patient to patient (range, 0.4% to 42.2%; mean, 18.8%) and differed significantly between acute lymphoblastic leukemia (ALL) and acute nonlymphoblastic leukemia (ANLL). In ALL, the Ki-67 LI showed a positive correlation with the S-phase fraction (SPF) determined by DNA FCM analysis, whereas, in ANLL, there was a discrepancy between the Ki-67 LI and SPF. In contrast, LI of PCNA varied less among the patients (range, 57.2% to 100%; mean, 90.3%), and the value was always higher than that of the Ki-67 LI in individual patients. A significant relationship between PCNA LI and the percentage of blast cells was found in peripheral blood leukocytes from patients with leukemia. These results suggest that the Ki-67 LI reflects differences in the proliferative activity depending on the subtype of the disease and that the PCNA LI is useful as a marker of proliferating cells.

Methotrexate cytotoxicity as related to irreversible S phase arrest in mouse L1210 leukemia cells

The association between cytotoxicity and cell cycle perturbation caused by methotrexate (MTX) was investigated in mouse L1210 leukemia cells by flow cytometric bromodeoxyuridine/DNA assay. In the range of concentrations of MTX from 10(-7) M to 10-6) M, in vitro exposure to the drug for 6 h caused a dose-dependent suppression of clonal growth of the tumor cells and S phase arrest in the cycle progression, resulting in an accumulation of cells in early S phase, in which they showed no definite increase of DNA content above G1 levels. The surviving fraction of the clonogenic cells corresponded with the fraction of cells which recovered from the S phase arrest in MTX-free medium. In mice bearing L1210 ascites tumors, a bolus injection of MTX caused the S phase arrest of the tumor cells as shown in suspension cultures, and cytokinetic recovery was observed in parallel with the regrowth of the tumor. These results showed that irreversible S phase arrest is a critical cytokinetic event associated with the cytotoxicity of MTX.

Flow cytometric evidence for minimal residual disease and cytological heterogeneities in acute lymphoblastic leukemia with severe hypodiploidy

Two subpopulations of small and large leukemia cells and binucleated cells were present in the bone marrow of a 10-year-old girl with acute lymphoblastic leukemia (ALL). Cytogenetic studies showed some cells with a karyotype of 34,X,-X,-2,-3,-4,-5,-7,-9,-13,-15,-16,-17,-20, and others with a karyotype that was exactly double the chromosome set in the cells with 34 chromosomes. Flow cytometric (FCM) examination of surface common ALL antigen (CALLA) and DNA content of the lymphoblasts led to the identification of the primary hypodiploid DNA stemline (DI = 0.72), which corresponds to the small-sized blasts, and the secondary hyperdiploid DNA stemline (DI = 1.44), which corresponds to the large-sized blasts. Sequential bone marrow examinations with FCM and cytogenetics revealed the persistence of the primary hypodiploid clone during remission and their proliferation with chromosomal evolution at full relapse. These results suggest that more rational inductive therapy should be designed to achieve the favorable outcome of ALL with severe hypodiploidy and that FCM is a useful tool to monitor the minimal residual disease of this subgroup in ALL.

Flow cytometric analysis by bromodeoxyuridine/DNA assay of cell cycle perturbation of methotrexate-treated mouse L1210 leukemia cells

The in vitro effects of methotrexate (MTX) on cell cycle progression and DNA synthesis of L1210 leukemia cells were studied by the bromodeoxyuridine (BrdUrd)/DNA analysis technique. Low dose (10(-8) M) MTX, which slightly inhibits clonal replication of the cells, delays progress across the S phase, and treatment for 24 h results in a slight increase of the S-phase population. Much higher doses (10(-7) M and 10(-6) M) of MTX, which strongly reduce the clonogenicity, prevented the progression of cells at the G1-S boundary and across the S phase, but not in the other phases. The cells arrested at the G1-S boundary were able to incorporate BrdUrd in the medium for 6-12 h after the start of treatment and then lost the ability to incorporate BrdUrd. By determining the colony inhibitory activity of MTX, it could be shown that not only S-phase cells but non-S-phase cells are susceptible to cytotoxicity of MTX. MTX-induced S-phase arrest is closely associated with an alteration in the distribution of BrdUrd-labeled cells, and MTX apparently inhibits BrdUrd incorporation into L1210 cells as the dose and duration of treatment increase. These results suggest that MTX-induced cell cycle perturbation is related to inhibition of DNA synthesis.

Prognostic implication of cellular DNA content in acute lymphoblastic leukemia

To assess the prognostic value of the cellular DNA content measured by flow cytometry in acute lymphoblastic leukemia (ALL), we studied the pretreatment distribution of the DNA content in marrow blasts from 74 children with this disease. They were divided into standard- and high-risk groups according to their white blood cell counts and age at the time of diagnosis and were followed for up to 44 months. Abnormal DNA stemlines were detected in 26 children, and all of them had a hyperdiploid DNA content (DNA index of greater than 1.0). The duration of remission was significantly longer in those with hyperdiploid DNA stemlines than in those with diploid DNA stemlines in both risk groups. In the standard-risk group, the DNA content and common ALL antigen were significant prognostic factors, especially the former. In the high-risk group, the DNA content also showed an independent significant correlation with the clinical outcome.

Effect of hydrocortisone and bacterial lipopolysaccharide on colony-stimulating activity production from mouse marrow adherent cells, spleen cells and peritoneal macrophages in vitro

The effect of hydrocortisone (HC) on colony-stimulating activity (CSA) production from mouse bone marrow adherent cells, spleen cells and peritoneal macrophages with or without bacterial lipopolysaccharide (LPS) stimulation was studied. CSA in the supernatant from bone marrow adherent cells incubated with HC was found to be five times higher than CSA from cultures without LPS stimulation. In contrast, the CSA production by spleen cells and peritoneal macrophages were significantly suppressed by HC in both LPS-stimulated and non-stimulated cultures. These studies suggest that the effect of HC on CSA production was quite different depending on the target cells.

Flow cytometric analysis of marrow cell kinetics in children treated with high-dose MTX and CF rescue

Normal marrow cell kinetics were studied by flow cytometry with computer analysis in 11 children with malignancies who received high-dose MTX followed by CF rescue. Nine children with hematological tumors in remission each received an infusion of MTX over 24 h, followed by delayed CF rescue. In 8 of the 9, an accumulation of cells in early to mid-S phase and a decrease of cells in G2/M phase were observed at 24-48 h after the beginning of the MTX infusion. At 144 h after MTX infusion this kinetic perturbation disappeared and the DNA histogram returned to the same state as before therapy. Two children who had malignant bone tumors without marrow infiltration each received an infusion of MTX over 6 h with early CF rescue following an initial IV injection of vincristine. They did not have any prominent perturbation of marrow cell kinetics after MTX exposure, except for a transient increase of cells in G2/M phase. These results confirm that with the high-dose MTX therapy described above for hematological malignancies the impairment of marrow cell kinetics was much more severe and was soon followed by complete recovery, whereas with the therapy for solid tumors the impairment was much slighter.

[Studies on high-dose methotrexate with citrovorum factor rescue therapy in children: analysis of bone marrow cell kinetics by flow cytometry]

Nine children in remission from hematologic malignancies received infusion of methotrexate (2,000-6,000 mg/m2) for 24 hours followed by citrovorum factor rescue (beginning 36 hours after the start of MTX infusion). Marrow cell kinetics of these patients were studied by flow cytometry with computer analysis. An accumulation of cells in the early-mid S phase and a decrease of cells in the G2/M phase were observed at 24-48 hours after exposure to MTX except for one infant case. By the 6th day after MTX infusion, the DNA histograms returned to pretreatment values. No kinetic perturbation was observed in the marrow cells of a 1-year, 5-month-old infant who showed high plasma MTX concentrations over the median values of the other eight children. These results show that profound but reversible changes are observed in marrow cell kinetics in most patients treated with our current high-dose MTX therapy with CF rescue and that a repeated course would be possible without cumulative marrow toxicity. More studies in young infants are needed to clarify the relationship between age and marrow toxicity of MTX so that treatment schedules with a higher therapeutic index can be designed.

Enhanced granulopoiesis in mice transplanted with colony-stimulating factor-producing BMA1 tumor

Inoculation of BMA1 cells into BALB/c nude mice formed tumors (BMA1 tumor) that were transplantable into ddY mice, and induced marked granulopoiesis in vivo. Histological study revealed that the tumor was a fibrosarcoma, some parts of which were calcified, and consisted of hemopoietic foci surrounded by adipose tissue. This tumor was regarded as producing CSF in vivo as well as in vitro, since CSF activity was detected in sera of the tumor-bearing mice and tumor extract. Granulopoiesis and splenomegaly developed, associated with an increase of stem cells in the spleen. The number of CFUc and CFUs in the spleen increased to about 91 times and 21 times those of control mice, respectively, whereas the number of stem cells in the tibia did not change significantly. The number of peripheral leukocytes increased to 15 times that of normal mice and amounted to 78% of matured granulocytes. After tumor resection these hematological changes were reversed. The findings suggest that the granulopoiesis in BMA1 tumor-bearing mice may be induced by CSF produced by BMA1 tumor and that the spleen may be a direct target organ of the excessive amount of CSF.

Effects of bacterial lipopolysaccharide on the production of colony-stimulating activity in C3H/HeJ mouse long-term bone marrow cultures

Bacterial lipopolysaccharide (LPS)-induced colony-stimulating activity (CSA) in murine long-term bone marrow culture system was investigated. Bone marrow culture cells of LPS-nonresponsive C3H/HeJ mice responded to LPS in terms of CSA production as efficiently as bone marrow culture cells of LPS-responsive C3H/slc mice. On the other hand, both peritoneal macrophages and bone marrow macrophages from C3H/HeJ mice did not produce CSA in vitro after treatment with LPS. Percoll density gradient separation of adherent layer cells in bone marrow cultures showed that two cell populations were present. One population was nonspecific esterase positive, productive of high CSA to LPS stimulation and light density cells, the other population was nonspecific esterase negative, productive of low CSA to LPS stimulation and high density cells, and CSA production stimulated by LPS in C3H/HeJ mice bone marrow culture cells was mainly attributed to the latter population of cells. These results suggest that CSA production stimulated by LPS in C3H/HeJ mice is regulated by different cell populations, respectively in vivo and in vitro.

Presence of colony-promoting activity-responsive cells as a separate compartment of granulocytic cell lineage in mice

A population of cells that responds to colony-enhancing factor has been reported to constitute the most immature subpopulation in the compartment of granulocyte/macrophage progenitors (GM-CFC). A similar colony-promoting activity (CPA) was found in the supernatant of long-term cultures of murine bone marrow cells. Here, some characteristics of the cells responsive to CPA were studied. The CPA-responsive cells in the spleen and bone marrow of W/WV mice were as numerous as in +/+ litter-mates. The concentration of CPA-responsive cells was independent of those of other cell populations, namely pluripotent stem cells (CFU-S), pluripotent precursor cells in vitro and GM-CFC in the spleen and bone marrow. Seeding efficiency in the spleen of irradiated mice and the cell-cycle state of CPA-responsive cells also differed from those of CFU-S and GM-CFC. Accordingly, the target of CPA appears to constitute a separate compartment in the progenitor populations of granulocytic lineage.

Survival and repopulation of irradiated 'pre-CFU-c' in mice

Supernatants of murine bone-marrow cultures contain a colony-promoting factor (CPF) which increases the number of granulocyte and macrophage colonies in semi-solid agar cultures in the presence of colony-stimulating factor (CSF). Incubation of bone-marrow cells with CPF results in an increase in the number of granulocyte/macrophage progenitor cells (CFU-c) and the CPF-responsive cells may be younger than the CFU-c. We have investigated the radiosensitivity and the pattern of the recovery after irradiation of CPF-responsive cells. We found that the radiosensitivity of CPF-responsive cells was significantly lower than those of CFU-c, burst-forming units-erythroid (BFU-e) and pluripotent stem cells in vivo (CFU-s) and in vitro (CFU-mix). The CPF-responsive cells remained subnormal even at 28 days after irradiation of the mice, a time when the CFU-s and CFU-c had recovered completely. Therefore the CPF-responsive cells may constitute a separate compartment, namely 'pre-CFU-c', in the maturation sequence of granulopoiesis, and this maturation of the 'pre-CFU-c' to CFU-c seems to be highly stimulated after irradiation to counterbalance the influx from CFU-s.

Colony promoting activity (CPA) produced in long-term culture of murine bone marrow cells

The differences between colony promoting activity (CPA) and colony stimulating activity (CSA) in the culture media of murine long-term bone marrow cultures (LTBMC) were demonstrated and the role of adherent cells and nonadherent cells in the production of CPA was studied in this culture system. Supernatant harvested from intact continuous marrow cultures showed high CPA but contained no CSA. Assayable CSA was detected in concentrated supernatant. However, there was no significant relationship between levels of CPA and CSA in the supernatant. When adherent cells and nonadherent cells from LTBMC were separately cultured, CPA was detected in the conditioned medium of adherent cells but not in that of nonadherent cells. The CPA level in LTBMC was related inversely to the number of nonadherent cells and addition of nonadherent cells to adherent cell cultures reduced the level of CPA. Conditioned medium of nonadherent cells showed no inhibitory activity of CPA. These results indicate that CPA is produced by bone marrow adherent cells and that it may be consumed by myeloid progenitor cells in nonadherent cells.

Effects of bacterial lipopolysaccharide and X-irradiation on the production of colony-stimulating factor and the maintenance of granulopoiesis in bone marrow culture

Effects of bacterial lipopolysaccharide (LPS) and X-irradiation on CSF production and granulopoiesis in long-term bone marrow cultures were studied. Levels of colony-stimulating factor (CSF) increased soon after the refeeding of the culture, but the activity was undetectable at day 7. Addition of LPS induced a significant increase in CSF levels in the culture, followed by an elevated granulopoiesis. The increase in CSF levels was suppressed when culture medium that had been harvested at refeeding on day 7 was added. Although irradiation did not increase CSF production, granulopoiesis was markedly stimulated shortly after irradiation. Thus granulopoiesis in long-term bone marrow culture may also be regulated by humoral factors such as CSF, and the culture system may represent the in vivo response to haemopoietic stimuli.