Dose-Rate-Dependent PU.1 Inactivation to Develop Acute Myeloid Leukemia in Mice Through Persistent Stem Cell Proliferation After Acute or Chronic Gamma Irradiation.

Radiation-induced acute myeloid leukemia (rAML) in C3H mice is commonly developed through inactivation of PU.1 transcription factor encoded in Sfpi1 on chromosome 2. PU.1 inactivation involves two steps: hemizygous deletion of the Sfpi1 gene (DSG) and point mutation of the allele Sfpi1 gene (PMASG). In this study, we investigated the dose-rate dependence of the frequency of both DSG and PMASG in hematopoietic stem cells (HSCs) of C3H mice that received a total of 3 Gy gamma-ray exposure at dose rates of 20 mGy/day, 200 mGy/day or 1,000 mGy/min. All mice were followed for 250 days from start of irradiation. Fluorescent in situ hybridization of the Sfpi1 gene site indicated that frequency of HSCs with DSG was proportional to dose rate. In cell surface profiles, PU.1-inactivated HSCs by both DSG and PMASG were still positive for PU.1, but negative for GM-CSF receptor-α (GMCSFRα), which is transcriptionally regulated by PU.1. Immunofluorescent staining analysis of both PU.1 and GM-CSFRα also showed dose-rate-dependent levels of PU.1-inactivated HSCs. This study provides evidence that both DSG and PMASG are dose-rate dependent; these experimental data offer new insights into the dose-rate effects in HSCs that can lead to radiation-induced leukemogenesis.

Membrane transport and apoptosis-related proteins in radiation-associated acute myeloid leukemia following the Chornobyl accident.

We report on the results of multidrug-resistance transporters (P-glycoprotein, LRP, and MDR1), and apoptosis-related proteins (Fas, Bcl-2, Bax, p53, and Bcl-X(L)) expression analysis of 56 acute myeloid leukemia (AML) patients by flow cytometry. Of these, there were 21 persons exposed to ionizing radiation due to the Chornobyl accident with radiation-associated and 35 patients with spontaneous AML. Leukemic cells in patients with radiation-associated AML more often overexpressed antiapoptotic protein Bcl-2 (12/21 vs. 6/35, p < 0.005) and less often demonstrated expression of Fas receptor (12/21 vs. 30/35, p < 0.05). Moreover, leukemic cells were simultaneously Fas negative and Bcl-2 positive in 4 out of 21 patients exposed to ionizing radiation but none of spontaneous cases had similar phenotype (p < 0.05). Patients with radiation-associated AML compared to spontaneous cases more often were P-glycoprotein positive (12/20 vs. 9/31, p < 0.05). P-glycoprotein overexpression significantly correlated with the resistance of the disease to chemotherapy in patients with radiation-associated AML (p < 0.05).

Secondary acute myeloid leukaemia: results of conventional treatments. Experience of GIMEMA trials.

BACKGROUND: The aim of the study was to evaluate the outcome of acute myeloid leukaemia (AML) in patients with a previous malignancy (sAML) treated with chemo- and/or radiotherapy, enrolled in conventional trials. PATIENTS AND METHODS: In a multicentre setting, a prospective non-concurrent analysis was performed on 2513 new AML patients, aged 12-78 years, consecutively enrolled in EORTC-GIMEMA trials between 1987 and 2001. Thirty-eight patients with sAML were identified and compared with a group of 114 de novo AML patients matched according to age, French-American-British criteria, white blood cell count at diagnosis, trial and time of diagnosis of AML. Induction treatment response, disease-free survival (DFS), duration and overall survival (OS) were evaluated in the two groups. RESULTS: Comparing the complete remission (CR) rate between 38 sAML patients and 114 de novo AML patients, selected according to the previously reported criteria, we observed no difference in the CR rates [25/38 (66%) versus 66/114 (58%); Pearson chi(2) 0.7393, P=0.390] as well as no differences while comparing the DFS and the OS between the two groups. CONCLUSION: The results of this study suggest that sAML patients are characterised by a good performance status permitting their recruitment in conventional trials without a previous myelodysplastic phase. Similar to de novo AML patients, sAML patients show good response to treatment and the possibility of cure.

Therapy-related acute promyelocytic leukemia.

PURPOSE: To analyze patient cases of therapy-related acute promyelocytic leukemia (tAPL), occurring after chemotherapy (CT), radiotherapy (RT) or both for a prior disorder, diagnosed during the last 20 years in three European countries. PATIENTS AND METHODS: The primary disorder and its treatment, interval from primary disorder to tAPL, characteristics of tAPL, and its outcome were analyzed in 106 patients. RESULTS: Eighty of the 106 cases of tAPL were diagnosed during the last 10 years, indicating an increasing incidence of tAPL. Primary disorders were predominantly breast carcinoma (60 patients), non-Hodgkin's lymphoma (15 patients), and other solid tumors (25 patients). Thirty patients had received CT alone, 27 patients had received RT alone, and 49 patients had received both. CT included at least one alkylating agent in 68 patients and at least one topoisomerase II inhibitor in 61 patients, including anthracyclines (30 patients), mitoxantrone (28 patients), and epipodophyllotoxins (19 patients). Median interval from primary disorder to tAPL diagnosis was 25 months (range, 4 to 276 months). Characteristics of tAPL were generally similar to those of de novo APL. With treatment using anthracycline-cytarabine-based CT or all-trans-retinoic acid combined with CT, actuarial survival was 59% at 8 years. CONCLUSION: tAPL is not exceptional, and develops usually less than 3 years after a primary neoplasm (especially breast carcinoma) treated in particular with topoisomerase II-targeted drugs (anthracyclines or mitoxantrone and less often etoposide). Characteristics and outcome of tAPL seem similar to those of de novo APL.

[Long-term results of treatment of chronic B-cell lymphoid leukocytes in persons who participated in the elimination of the effects of the nuclear accident at the Chernobyl nuclear station]. / Rezul'taty likuvannia khronichnoho B-klitynnoho limfoleikozu v uchasnykiv likvidatsiï naslidkiv avariï na ChAES u viddalenomu periodi.

Clinical-and-hematological characteristics are presented of B-cell chronic lymphoid leukosis in those persons who took part in the elimination of the effects of the Chornobyl accident in the remote period. Results are highlighted of treatment of 16 patients with making use of different chemical drug preparations. Employment of fludarabin and cyclophosphan combined in treatment of the medical condition in question has been shown to promote long-term complete and partial remissions in a major proportion of patients, which effect was not achievable with standard means of remediation. A side effect of fludarabin was leukocytopenia that in the presence of changed immunity threatened the patients with development and exacerbation of infections complications. Use of manax and erbisol moderated the immunosuppressive and toxic action of fludarabin, due to which fact infectious complications and drug-induced hepatitis have came to be less common, the patients' quality of life gotten better.

The combination of chemotherapy and systemic immunotherapy with soluble B7-immunoglobulin G leads to cure of murine leukemia and lymphoma and demonstration of tumor-specific memory responses.

Major mechanisms underlying poor immune responses to autologous tumor-associated antigens are overwhelming tumor kinetics and the absence of effective T-cell costimulation by antigen-presenting cells. To address these issues, leukemia and lymphoma mice were treated with the combination of chemotherapy and systemic immunotherapy with recombinant soluble murine B7-immunoglobulin G (IgG) molecules. In this report, 3 murine models were used, a radiation-induced SJL acute myeloid leukemia, a transplantable spontaneous SJL lymphoma, and the C57BL/6 EL-4 thymic lymphoma. Various treatment modalities were evaluated: single treatments with either B7-IgG or chemotherapy as well as combination therapies. The results demonstrate the following: (1) in all tumor models, the combination of chemotherapy and soluble B7-IgGs is more potent than either therapy alone, leading to cure of tumor-bearing animals; (2) the therapeutic responses are T-cell-dependent, because combined therapy is not efficacious in severe combined immunodeficient mice; (3) the rejection of tumor cells leads to the development of tumor-specific immunity, because cured mice are immune to the rejected tumor but not to a different syngeneic tumor; and (4) (51)Cr release assays show that rejection of tumor cells leads to the development of very potent tumor-specific cytotoxic T-lymphocyte activity. On the basis of these results, it is proposed that chemotherapy-mediated tumor reduction, together with consequent augmented tumor-antigen presentation to activated T cells, are primary mechanisms leading to curative responses. The safety profile of the B7-IgG fusion proteins and their synergy with chemotherapy strongly suggest that the combination regimen is a promising strategy in cancer treatment.

Chemotherapy of secondary leukemias.

Chemotherapy of secondary leukemias is currently still considered to be associated with poor results. However, recent data suggest that the response to remission induction may substantially differ according to the previous medical history of the patients. Therapy related leukemia, arising following exposure to previous alkylating agents or radiotherapy, is often associated with chromosomal abnormalities involving chromosomes 5 and 7 and has a particularly bad response, whereas AML after exposure to epipodophyllotoxins or topoisomerase-II active agents could have a somewhat better response. Acute promyelocytic leukemia secondary to treatment of a primary malignant neoplasm seems to be associated with a better response if compared to other cytotypes of AML or to AML arising after transformation of myelodysplasia. However, here the literature data are not in full agreement, as different kinds of approaches have been applied. In fact, even if the problems encountered in treating patients with secondary leukemia are similar to those seen in patients with AML arising in a background of myelodysplasia (resistant disease and prolonged cytopenia after treatment), there are data suggesting that the use of high dose ara-C, with or without fludarabine, can circumvent resistance in a small but significant number of cases. One of the unsolved problems which still remains is how to consolidate the CR induced with high dose ara-C or with cycles based on anthracycline derivatives. In addition, another question relates to the categories of patients in whom chemotherapy may change the expected survival. Intensive post-remission chemotherapy, with or without autologous HSCT, may constitute an appropriate alternative for patients lacking a suitable sibling donor or for older patients who are in remission after chemotherapy and also able to tolerate other cycles of intensive chemotherapy. In this respect, the specific cytogenetic abnormality involved should be considered the most important prognostic factor for response and disease free survival; patients with abnormalities of chromosome 5 and 7 have a particularly low possibility of response and duration of CR. Furthermore, it is still debatable whether patients, especially the elderly, with these characteristics should go through a series of conventional treatments or just receive supportive treatment. On the other hand, patients with better prognostic factors should be entitled to further intensive treatments, taking into account possible delayed recovery and/or possible less successful collection of peripheral or marrow stem cells.

Gamma radiation induced leukemia in ICRC strain of mice: a murine model closely simulating human disease for experimental chemotherapy.

We report here a murine model of transplantable lymphoblastic leukemia closely simulating human disease in albino mice of ICRC strain. Both male and female mice of this strain developed leukemia with high incidence (approximately 70%) following whole body exposure to 60Co Gamma Rays (Dose: 1.5 Gray/Week x4). The latent period for development of leukemia was six months. In the leukemic mice there is marked leucocytosis with presence of lymphoblasts in peripheral blood. These blasts infiltrate various organs like liver, spleen, kidney, lymph nodes, testes and brain, Neoplastic cells are T lymphoblasts expressing weak Thy 1.2 membrane antigen and found sensitive to anticancer drugs. Salient features of the murine model are described.

Stem cell transplantation for secondary acute myeloid leukemia: evaluation of transplantation as initial therapy or following induction chemotherapy.

The purpose of this report is to describe the results of stem cell transplantation as initial treatment for secondary acute myeloid leukemia (AML). Forty-six patients (median age 42 years) with secondary AML (17 therapy-related, 29 myelodysplasia-related) who had not received remission induction chemotherapy underwent allogeneic (n = 43) or syngeneic (n = 3) transplantation. The 5-year actuarial disease-free survival was 24.4%, and the cumulative incidences of relapse and nonrelapse mortality were 31.3% and 44.3%, respectively. Lower peripheral blood blast count was associated with a lower risk of relapse (P = .05) and shorter time from AML diagnosis to transplant was associated with a lower risk of nonrelapse mortality (P = .02) and improved disease-free survival (P = .026). Patients with therapy-related secondary AML tended to have lower disease-free survival (P = .16) and a higher relapse rate (P = .16) than patients whose leukemia was not therapy-related. The results of these 46 previously untreated patients were compared to 20 patients (median age 36 years, 12 therapy-related, 8 myelodysplasia-related) transplanted with chemotherapy-sensitive disease after induction chemotherapy (first complete remission [n = 6], second complete remission [n = 3], first untreated relapse [n = 11]). We found no statistically significant difference in outcome between these 2 groups of patients. These results suggest that prompt transplantation should be considered after diagnosis of secondary AML or, if possible, high-risk myelodysplasia, particularly in patients with low peripheral blast counts. Innovative transplant strategies are needed to reduce the high risks of relapse and nonrelapse mortality seen in this patient population.

Idarubicin, high-dose cytarabine and etoposide for remission induction in therapy-related acute myeloid leukemia.

Five patients with therapy-related acute myeloid leukemia received combination induction chemotherapy with idarubicin, high-dose cytarabine, and etoposide. Complete remission was achieved in all patients with a single course of therapy. Treatment-related toxicity included nausea, vomiting, mucositis, diarrhea, and liver and kidney function abnormalities, and was low in all patients. There were no deaths during induction therapy. We conclude that this combination is well-tolerated in induction of remission in secondary acute myeloid leukemia, and warrants further assessment because of a very good complete remission rate.

Treatment of gamma radiation-induced transplanted leukemia in ICRC mice by liposomally encapsulated 5-fluoro uracil.

The present investigation reports on the efficacy of 5-FU encapsulated in liposomes for the treatment of leukemia using a murine model of gamma radiation-induced transplantable leukemia in ICRC strain of mice. Multi-lamellar vesicles (MLVs) or large unilamellar vesicles (REVs) prepared using phosphatidyl choline and cholesterol in a molar ratio of 8:2 for neutral and 7:2:1 for charged vesicles were administered as a single i.p. dose in mice. 5-FU encapsulated in MLVs at a concentration of 0.6-2.5 mg/kg had no effect, whereas REVs at a single i.p. dose of 9 mg/kg increased survival of leukemic mice with T/C = 138%, decreased peripheral blood count and considerably reduced infiltration of leukemic cells in different tissues (supported by histopathology) as compared to 60 mg/kg of free drug (LD10 = 70 mg/kg).

Therapy-related acute promyelocytic leukemia: a report on 16 cases.

PURPOSE: To analyze the type of prior tumor and treatment in therapy-related acute promyelocytic leukemia (tAPL) that occurs after chemotherapy and/or radiotherapy (RT), and the hematologic characteristics and outcome of tAPL. PATIENTS AND METHODS: Sixteen patients with tAPL who were gathered during a 10-year period (1982 to 1991) in seven hematologic centers were analyzed retrospectively. RESULTS: There were 13 women and three men. The median age was 46 years (range, 12 to 82). Prior tumor was breast carcinoma in 10 cases, another solid tumor in three cases, and lymphoma in three cases. Two patients had received RT alone, and 14 had received chemotherapy (with RT in 11 cases). Prior chemotherapeutic agents generally included a combination of cyclophosphamide (used for limited periods), fluorouracil (5-FU), vinca alkaloids, and doxorubicin, mitoxantrone, or etoposide (VP16). By contrast, alkylating agents other than cyclophosphamide had been used in only two patients. Median interval between onset of treatment for the prior tumor and diagnosis of APL was 25 months. No patient had a known preleukemic phase. Hematologic and cytogenetic characteristics of the cases of tAPL were identical to those of the usual de novo APL, which included the presence of t(15; 17) in nine of the 10 patients tested. Two patients had early death. Seven patients were treated with intensive chemotherapy, and six achieved complete remission (CR). Three of them subsequently relapsed. Seven patients were treated with all-trans-retinoic acid (ATRA), and four achieved CR through the differentiation of blasts into mature granulocytes. None has relapsed so far. CONCLUSIONS: Our findings suggest that tAPL is not exceptional, and usually has several features in common with other types of therapy-related AML with specific karyotype (ie, t(8;21),t(9;11), inv(16)): solid tumor rather than hematologic malignancy as primary tumor, short interval of development, absence of known preleukemic phase, prior chemotherapy with a combination of several drugs that often included an agent that targets topoisomerase II (doxorubicin or mitoxantrone, but less often VP16). Hematologic characteristics and response to therapy (intensive chemotherapy or ATRA) in tAPL do not seem to differ from those of de novo APL.

[High dosage and intermediate dosage cytosine arabinoside in the treatment of secondary leukemias]. / Hochdosiertes und mittelhochdosiertes Cytosinarabinosid zur Behandlung von sekundären Leukämien.

Patients with secondary acute myeloid leukaemia (AML) following treatment with alkylating agents and/or radiation show a poor response to standard induction therapy. Between 1983-1987 8 consecutive patients were treated with high-dose cytosine arabinoside (HD-ARA C; 3 g/sqm twice daily for 6 days) or intermediate-dose cytosine arabinoside (ID-ARA C; 0.5 g/sqm twice daily for 6 days). Complete remission was achieved in 3 patients (HD-ARA C: 2/3l; ID-ARA C: 1/5) and partial remission in 3 patients (ID-ARA C: 3/5). One patient (HD-ARA C) died during prolonged aplasia, one patient (ID-ARA C) proved refractory to treatment. The respective duration of remission in the 3 responsive patients was 3, 7 and 8 months. The probability of survival of the whole group was 50% after 12 months and 25% after 24 months. Our results confirm the efficacy of monotherapy with ARA C in the treatment of secondary AML. Consolidation therapy with ID-ARA C for 4 days seems to prolong remission.

Treatment of primary radiogenic C57BL mouse cell leukemia/lymphoma by 1,3-bis(2-chloroethyl)-1-nitrosourea chemotherapy and adjuvant cellular therapy.

Primary radiation-induced or radiation leukemia virus (RadLV)-induced T-leukemias/lymphomas were treated in vivo in an early to advanced state by using 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). BCNU was given at various times after the tumor induction procedure. Death from RadLV lymphomas which had been initiated in 33 +/- 3 day old C57BL mice by intrathymic injection of RadLV was scored in untreated, BCNU-treated or BCNU and cellular adjuvant treated mice. Intrathymic RadLV injection in 33 +/- 3 day old mice produced tumors in 98% of injected mice. Median survival time (MST) was increased by BCNU and by BCNU plus bone marrow cell therapy whether done 33 or 47 days after RadLV. There was increased in MST from 108 days to 171 days by BCNU and bone marrow cell therapy given 33 days after tumor initiation and to 195 days when therapy was given 47 days after initiation. In radiation-induced lymphomas produced by 190 rad every week X 4 of 33 +/- 3 day old mice, spleen cell (X 1) therapy or BCNU treatment increased the MST of treated mice from 142 days to 177 days after iv spleen cells or to 195 days after iv-ip spleen cells, and this protocol produced 31% long-term cures. Cellular adjuvant therapy combined with BCNU chemotherapy was effective for curing the lymphomas but cellular adjuvant therapy alone was also highly effective for therapy.

Response of therapy-associated acute nonlymphocytic leukemia to intensive induction chemotherapy.

Among 31 consecutive patients who developed acute nonlymphocytic leukemia following treatment with chemotherapy or radiation therapy, 17 were treated with intensive chemotherapy aimed at inducing a complete remission. Seven of these 17 patients (41%) obtained a complete remission that ranged in duration from 2 to 11 (median 3) months. Two additional patients who failed to develop normal peripheral blood counts despite postinduction bone marrows that were normocellular and free of leukemia were classified as nonresponders. The median time to complete remission and median duration of leukopenia (WBC less than 1,000/mu 1) were 34 days and 23 days, respectively. Induction chemotherapy was complicated by fever in all patients, documented infection in six patients, and death secondary to sepsis in three. Survival of the 17 patients ranged from less than 1 to 39 (median 4) months. Patients achieving a complete remission had a median survival time of 10 months compared to 2 months for the nonresponders. The other 14 patients received only supportive care and had a median survival of 2 months. These findings indicate that therapy-associated acute nonlymphocytic leukemia (t-ANLL) can frequently respond to chemotherapy and that achieving a complete remission is associated with longer survival. Although these results are encouraging, patients with t-ANLL still have a relatively poor prognosis and efforts directed at improving treatment outcome need to be continued.

1,3-bis(2-chloroethyl)-1-nitrosourea treatment of spontaneous radiogenic C57BL mouse leukemia/lymphoma.

Spontaneous radiation-induced or radiation leukemia virus (RadLV)-induced leukemias were treated in vivo in an early-to-advanced lymphomatous state by using 1,3-bis(2-chloroethyl)-1-nitrosouea (BCNU). BCNU was given at various times after the tumor induction procedure. Treatment was based upon the findings that the RadLV-derived transplant lymphosarcoma (LSA) tumor was cured with a frequency of greater than 90% and a tumor-resistant state was produced by tumor cure. Death from RadLV lymphomas which had been initiated in newborn C57BL mice by ip injection of RadLV was scored in untreated or BCNU-treated mice. At 150 days after initiation, control mice had developed extensive thymic lymphomas, whereas BCNU-treated mice had developed less extensive tumors, had a reduced incidence by approximately 50% and had an increased survival time. Similar findings were noted for the radiation (190 rad of cobalt-60 gamma rays weekly X 4)-induced thymic lymphoma-bearing C57BL mice. Injection of 10(6) living LSA cells before BCNU treatment greatly decreased the tumor load for all groups treated but also shortened the mean survival time. Challenge of long-term survivors with small numbers of viable LSA tumor cells did not identify any host resistance of the survivors to the transplant LSA tumor and indicated that the induction procedure, whether RadLV or radiation, was strongly immunosuppressive.

Effective chemotherapy of acute myelocytic leukemia occurring after alkylating agent or radiation therapy for prior malignancy.

Eleven consecutive patients with acute myelocytic leukemia occurring as a second malignancy were treated with high-dose, timed, sequential chemotherapy. Eight of the patients were felt to have "secondary" acute leukemia because they had received an alkylating agent or radiation therapy. The other three patients were considered controls. Despite a median age of 65, four of the eight secondary leukemia patients achieved complete remission with this regimen. One of the three control patients also achieved complete remission. This remission rate and duration are comparable to what was achieved with this treatment of "primary" acute myelocytic leukemia during the same period of time. These results suggest that patients with leukemia occurring after an alkylating agent or radiation therapy are not at especially high risk if treated aggressively.