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Children with acute lymphocytic leukemia can be apparently cured today. The subclassification of ALL in childhood as “high risk” and “standard risk” ALL by means of a determination of immunologic and clinical parameters is of increasing importance. This classification could become the basis for a risk-oriented individual therapy. We present here the current results attained in the treatment of childhood ALL by our Pediatric Hematology and Oncology working group involving 13 treatment centers of the German Democratic Republic.

Children with relapsed common acute lymphoblastic leukemia (ALL), B-non-Hodgkin lymphoma (B-NHL), and B-acute lymphocytic leukemia (B-ALL) have a very poor prognosis. If there is no HLA-identical donor, the patient should be considered for autologous bone marrow transplantation. Collected autologous marrow should be cleansed of contaminating tumor cells without destroying hemopoietic stem cells. We report here the results of our investigations with a cocktail of three monoclonal antibodies (VIL-A 1, VIB-C 5, and VIB-E 3 — the VIB pool — kindly given to us by Dr. Knapp of Vienna) concerning in vitro cytotoxicity against ALL blast cells and leukemic cells lines, lytic capacity with rabbit and human complement, and stem cell toxicity, together with our findings concerning the ex vivo purging of the marrow of four children.

The most important problem in current therapy of childhood acute lymphoblastic leukemia (ALL) is a failure in over one-half of patients. We were unable to increase the failure-free survival of children with high risk ALL by a ten-drug regimen (modified LSA2L2) above 30% at 6 years [1].

Xenogeneic antisera were produced against human O-ALL and T-ALL and tested against leukemia and normal cells by the complement-dependent cytotoxicity technique. After appropriate absorptions with normal cells, the two O-ALL antisera tested reacted with cells of about 50% of O-ALL patients. They did not react with cells of T-ALL, B-ALL, normal WBC, enriched B-lymphocytes or thymus lymphocytes. The antigen involved is present on cells of young human fetuses, since fetal liver cells are lysed in the cytotoxicity test and whole fetal tissue removes antibody activity against O-ALL cells. The three T-ALL antisera reacted with T-ALL cells and only with a minority of O-ALL cells. Among the other normal and malignant cells which have been tested, only thymus and fetal liver cells were positive. Thymus cells removed antibodies to thymus, but not to T-ALL and fetal liver. However, antibodies to T-ALL are completely removed by absorptions with fetal tissue. The experiments indicate that cells of O-ALL and T-ALL express fetal antigens and that the fetal antigens of the two types of ALL are immunologically distinct.

In contrast to recent advances in the treatment of acute lymphoblastic leukemia (ALL) where cure rates of nearly 70% have been obtained [1, 2], the outcome of the treatment for acute nonlymphoblastic leukemia (ANLL, AML) is less successful. In general, remission rates of about 70% have been obtained [3–9]. But the relapse rate is high, and so CCR rates of 50% after 2–3 years are exceptions [3, 4, 10].

Multidrug resistance is an important mechanism responsible for refractoriness of leukemia and worse outcome of patients. Overexpression of the multidrug resistance gene, MDR1, is of prognostic relevance in acute myeloid leukemia, while its role in acute lymphoblastic leukemia (ALL) is still under debate. Single nucleotide polymorphisms (SNP) have been detected in the MDR1 gene. The C3435T polymorphism in this gene seems to have functional and clinical consequences. In the present investigation, we have analyzed the role of the C3435T SNP for drug resistance and prognosis of human ALL. The C3435T SNP was analyzed in 20 T-ALL cell lines and in blood samples from 53 ALL patients and 7 healthy donors. The cell line panel consisted of cell lines not prior exposed in vitro to cytostatic drugs as well as of drug-resistant lines which were selected in vitro by exposure to doxorubicin, vincristine, methotrexate, or hydroxyurea. We have developed a highly sensitive matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS)-based genotyping approach to survey the C3435T SNP. Furthermore, mRNA expression was determined by real time reverse-transcribed polymerase chain reaction and doxorubicin sensitivity by a growth inhibition assay. Surprisingly, we did not find a significant correlation between C3435T homo- or heterozygote genotypes and MDR1 mRNA expression of cell lines or blood samples from patients and healthy donors. Furthermore, there was no relationship between the response of the cell lines to doxorubicin and the C3435T genotypes. Homo- or heterozygosity did not correlate to survival of patients in the Kaplan-Meier analysis. In conclusion, we do not have reason to assume that the C3435T SNP contributes to drug resistance of ALL and prognosis of ALL patients.

UNLABELLED Patients with nephroblastoma have a high risk of relapse if they present with stage IV and anaplastic histology or with extraregional lymph node involvement; at time of relapse, bad prognosis is heralded by recurrence in an irradiated region, second or subsequent relapse, early first relapse (6 months after nephrectomy), relapse with adverse histology, relapse in two or more organ systems and lymph node or bone metastases at relapse. For such patients, an attempt to increase survival by high-dose chemotherapy seems to be justified. In 8 children aged 7.3 years (3.8-14.7) treated within the German Nephroblastoma Study SIOP9/GPOH, high dose chemotherapy with autologous hematopoietic rescue was instituted for the following reasons: stage IV with anaplastic histology and extra-regional lymph nodes (1), second or subsequent pulmonary relapse (3), early relapse with diffuse pleural (1) or skeletal (1) dissemination, recurrence in irradiated area (1) and lung metastases after early local relapse (1). At megatherapy, the patients were in first (1), second (2), third (2) and fourth complete (2) or in partial remission (1). The high dose regimen consisted of carboplatin, etoposide and melphalan. Treatment related toxicity, all non-lethal, included acute but reversible renal failure (1), esophagitis with need of parenteral nutrition for 6 months (1), cardiomyopathy (3; chronic in 1). After a follow-up of 2.1 years (0.5-3.7), 6/8 patients survive in complete remission; for 5 of them who are in remission since > 18 months a recurrence is unlikely. Both children with local relapse died after a further recurrence 3 and 8 months after high dose treatment. CONCLUSION High dose consolidation with ASCR seems to effectively ameliorate the prognosis of patients with high risk nephroblastoma.

The purpose of this investigation was to evaluate the expression profile of proteins involved in children with newly diagnosed acute lymphoblastic leukemia (ALL) children who are developing relapses. For this reason, the expressions of 10 proteins including proto-oncogene and tumor suppressor gene products, proliferative factors and resistance parameters in 104 initial cases of childhood ALL were analyzed and the proteins correlated with ALL patients who experienced relapses. Applying immunocytochemical assays, we found that 4 out of the 10 parameters revealed a relationship to developing relapses (Fisher's exact tests). These were the oncogene product Fos (p=0.002), the drug resistance proteins glutathione S-transferase (p=0.008) and P-glycoprotein (P-pg/MDR1) (p=0.07) and protein kinase C (p=0.01). By means of hierarchical cluster analysis, we were able to show that the patients could be separated according to their protein expression profile into clusters consisting of patients whose ALL relapsed later and of patients who did not show relapses in the future.