Cytotoxic Drugs and Leukaemogenesis

Is prevention of cancer possible with tumor-specific vaccines?

Cancer is one of the leading causes of death today, and new therapeutic approaches are continuously being explored. In recent years, cancer vaccines have been tried with the aim of induction of an active specific immune response against the tumor. Although some successful results are obtained, cure rates are still disappointing. The main reason for failure is that vaccines are applied to patients diagnosed with cancer; in these patients, tumor cell burden is so high that it is almost impossible to overcome the disease by increasing the immune response with vaccines at this stage. This hypothesis is based on the following idea: since therapy for cancer is unsuccessful in the majority of patients, methods of prevention should be improved. Immunization against microorganisms has largely prevented morbidity and mortality from infectious disease. In a similar way, if we immunize people before the development of malignant disease with tumor-specific vaccines, then prevention of cancer may be possible.

Prognostic factors in the myelodysplastic syndromes

The myelodysplastic syndromes are acquired clonal hematologic malignancies characterized by progressive cytopenia and an increased risk of evolution to acute myeloid leukemia. It mainly affects elderly people, but may also be found in younger patients and children. MDS represents a heterogeneous group of disorders. Some patients will experience prolonged survival, whereas a substantial number of patients will die within the first year after diagnosis. Treatment of patients should be based on life expectancy. Patients with pancytopenia, excess of bone marrow blasts, complex chromosome abnormalities, abnormal chromosome 7, older age and secondary MDS have a poor prognosis. Several simple scoring systems are available, based on peripheral counts, percent of bone marrow blasts and age, that provide significant prognostic information about life expectancy in patients with MDS. The most widely used is the Bournemouth scoring system. The prognostic factors and the scoring systems are reviewed.

Occupational history and involvement of chromosomes 5 and 7 in acute nonlymphocytic leukemia

We compared the histories of exposure to leukemogens for two groups of patients presenting with myelodysplastic syndrome (MDS) or acute nonlymphocytic leukemia (ANLL). In one group there were 59 patients with an acquired abnormality of chromosomes 5 or 7 in the marrow at time of diagnosis. In the other group there were 39 patients with a normal marrow karyotype at the time of diagnosis. A much higher proportion of the chromosomally abnormal cases had a history of treatment for a previous malignancy (odds ratio = 13.0, p less than 0.01). There was little difference found between the occupational histories of the patients with de novo ANLL with and without cytogenetic abnormalities. An occupational history of exposure to chemicals or metals was more common in males with either a deletion of the long arm of chromosome 7 or with monosomy 7 or monosomy 5 (82.3%) than in males with a normal karyotype (52.1%). The odds ratios did not, however, reach statistical significance.

Specific chromosome changes and nonoccupational exposure to potentially carcinogenic agents in acute leukemia in China

Cytogenetic studies were performed on 44 Chinese patients with acute leukemia. A high percentage of patients (37.5%) with t(8;21), t(15;17) or 17q- (in poorly banded preparations), and abnormalities involving 11q23 were noted in 32 unselected patients with ANLL. A similar high percentage was previously reported in Japan and in South Africa but not in western countries. Data on casual or other non-occupational exposure to potentially carcinogenic agents were obtained by interview with the patients at their first presentation. Most patients with these three major chromosomal changes had a history of exposure, whereas most other patients did not (p = 0.01). Patients with ANLL-M3 were more often exposed than were the other patients (4/6 vs 8/38, p = 0.03). The only common exposure was to organophosphate insecticides. Twenty seven cases of therapy-related leukemia were collected from the Chinese medical literature, and 12 out of 22 (55%) cases in which subtypes were specified were ANLL-M3. This was significantly higher than the percentage of M3 in de novo ANLL in China and also higher than that of therapy-related leukemia from western countries. Two patients had siblings who died of leukemia at a similar age. The two patients showed inv(16) and del(6q) respectively.

Second malignancies and Hodgkin's disease--the Royal Marsden Hospital experience

The frequency of secondary malignant neoplasms occurring in patients treated for Hodgkin's disease at the Royal Marsden Hospital between 1963 and 1978 is reported and the literature is reviewed. 730 patients were reviewed and 583 patients permanently resident in the United Kingdom were included in the analysis. The frequency of leukaemia and solid tumors was determined from age- and sex-corrected data from the South Thames Cancer Registry. Thirty-seven malignancies were recorded in 36 patients including 9 leukaemias, 10 lung cancers, 6 skin cancers and 2 non-Hodgkin's lymphoma, all of which were observed in significant excess. When all remaining sites are combined, there was a slight excess but no one site is individually significant.

Chronic myelocytic leukemia as a second neoplasia in the course of chronic lymphocytic leukemia. Case report and review of the literature

A patient with chronic lymphocytic leukemia developed Ph1-positive chronic myelocytic leukemia after a 6-yr course of CLL. Chemotherapy for CLL consisted of chlorambucil and steroids, later vincristine and bleomycin; after resistance to these agents, cyclophosphamide, vincristine and prednisolone were applied. When CML was diagnosed, we found two morphologically distinct populations of malignant cells in the bone marrow; the Ph1-chromosome was identified, and immunological surface marker studies also demonstrated two distinct malignant cell populations. Up to now, only five cases of CML have been reported following CLL and one case accompanying it. Three patients were treated with cytostatic drugs, one patient by total body irradiation and two patients received no therapy. At present, it is not clear whether the development of CML during CLL represents a therapy-induced complication or an increased susceptibility to second malignancies due to the leukemic process itself or possibly to immunological deficiencies in CLL. Since two patients received no treatment for CLL, previous therapy does not seem to be a prerequisite for the development of CML.

Myelodysplastic syndromes: pathogenesis, functional abnormalities, and clinical implications

The myelodysplastic syndromes represent a preleukaemic state in which a clonal abnormality of haemopoietic stem cell is characterised by a variety of phenotypic manifestations with varying degrees of ineffective haemopoiesis. This state probably develops as a sequence of events in which the earliest stages may be difficult to detect by conventional pathological techniques. The process is characterised by genetic changes leading to abnormal control of cell proliferation and differentiation. Expansion of an abnormal clone may be related to independence from normal growth factors, insensitivity to normal inhibitory factors, suppression of normal clonal growth, or changes in the immunological or nutritional condition of the host. The haematological picture is of peripheral blood cytopenias: a cellular bone marrow, and functional abnormalities of erythroid, myeloid, and megakaryocytic cells. In most cases marrow cells have an abnormal DNA content, often with disturbances of the cell cycle: an abnormal karyotype is common in premalignant clones. Growth abnormalities of erythroid or granulocyte-macrophage progenitors are common in marrow cultures, and lineage specific surface membrane markers indicate aberrations of differentiation. Progression of the disorder may occur through clonal expansion or through clonal evolution with a greater degree of malignancy. Current attempts to influence abnormal growth and differentiation have had only limited success. Clinical recognition of the syndrome depends on an acute awareness of the signs combined with the identification of clonal and functional abnormalities.

Karyotypic evolution in Ph-positive chronic myeloid leukemia in relation to management and disease progression

In a prospective study of 32 patients with chronic myeloid leukemia the frequency of chromosome abnormalities in addition to the Philadelphia chromosome (Ph) increased when the disease progressed. Before metamorphosis, 10 patients (31%) had developed additional abnormalities. Such abnormalities were present in three of them at the time of diagnosis; in the other seven, they were detected late in the chronic phase. New clonal abnormalities heralded or accompanied a more malignant phase of the disorder, usually a blastic leukemia. During metamorphosis, 78% of the patients had additional abnormalities, which in 68% of these cases comprised at least one of +8, +22q- or i(17q). Clones with additional abnormalities disappeared in eight cases, either spontaneously or in association with cytostatic therapy during the chronic or blastic phase. Involvement of chromosome #8, usually in the form of a trisomy, was found in 7 of 12 patients treated with busulfan, but was not found in any of the 10 hydroxyurea-treated patients, of whom 8 were splenectomized early during the chronic phase. Cells from the spleen, obtained by fine needle aspiration or splenectomy were cytogenetically examined in 18 cases during the chronic phase, but abnormalities in addition to the Ph were noted in only one patient, who was examined in the late chronic phase. The same abnormalities were present in bone marrow cells of this patient.

The 5q-anomaly

A deletion of the long arm of chromosome #5 (5q-) occurs nonrandomly in human malignancies. As a rule, the deletion is interstitial; the distal breakpoint by conventional techniques is usually in band q32, the proximal breakpoints in q12 or q14. Variant breakpoints occur in less than 10% of all cases. As the sole anomaly, 5q- is characteristically found in refractory anemia with or without excess of blasts. It can occur as the sole anomaly in de novo or secondary acute nonlymphocytic leukemia, but is usually accompanied in those disorders by other chromosome changes that are also nonrandomly distributed. In addition, it can be found in lymphoproliferative disorders, and occasionally, also in solid tumors. The 5q- myelodysplastic syndrome typically occurs in older age groups, particularly in females. Characteristic features are macrocytic anemia, normal or elevated platelets in the presence of megakaryocytic anomalies, and a mild clinical course. In cases with 5q- only, transformation into ANLL occurs rarely. Additional chromosome anomalies and male sex are prognostically unfavorable signs. Sex ratio is also at the disadvantage of females in de novo 5q- ANLL, and the latter disorder can occur without being preceded by a myelodysplastic phase. A myelodysplastic phase usually precedes 5q- secondary leukemia, in males as well as in females, and additional chromosome anomalies, especially of chromosome #7, are almost invariably present in those cases. We conclude that 5q- is the most frequently occurring single chromosome anomaly in secondary leukemia. Furthermore, the resemblance between de novo and secondary 5q- MDS and ANLL is striking; clinically, as well as cytogenetically, they are indistinguishable, suggesting that all de novo cases may be due to environmental (chemical) carcinogens. Response to treatment and prognosis are very poor with current therapeutic regimens in de novo as well as in secondary 5q- ANLL. Morphologically, these ANLLs fall into all FAB categories. There is considerable evidence to show that the 5q- anomaly occurs in a myeloid precursor stem cell. The occasional occurrence in lymphoid malignancies, of B cell as well as T cell type, suggests that, as in Ph-positive disorders, a common progenitor stem cell may be affected in 5q- also. The 5q- lymphoid malignancies, however, are much more rare; it is not clear at the present time whether or not a 5q- counterpart of Ph-positive ALL exists, and mixed lymphoid-myeloid 5q- disorders have not yet been documented.(ABSTRACT TRUNCATED AT 400 WORDS)

Second cancers following antineoplastic therapy

The occurrence of metachronous malignancies has long been a phenomenon of interest to physicians. The problem of treatment-related malignancies has added to that interest and has contributed to the understanding of carcinogenesis. Prolonged survival of patients with previously lethal diseases is now allowing the expression of long-term toxicities of the intensive therapies being used in many disease settings. Although the oncogenic potential of the various alkylating agents may not be equivalent, they have all been implicated as causing cancer in man. Procarbazine also appears to be highly carcinogenic in man. The intensity of treatment (duration and total dose) is a significant factor in the carcinogenesis of these agents. The dose-response relationship between radiation and cancer induction is less clear, but most believe that increasing radiation exposure increases the risk of cancer in a linear fashion. The combination of intensive chemotherapy and intensive radiotherapy yields the greatest risk for treatment-related hematologic and solid malignancies. To replace effective therapy with less carcinogenic therapy of unproved effectiveness would be difficult since survival curves have not been significantly affected by the evolution of treatment-related cancers. Whether that will hold true for the adjuvant use of intensive therapy remains to be seen. Where feasible, the design of such adjuvant trials should keep the dose-response relationship in mind. If the virtual absence of metachronous leukemia in Hodgkin's disease patients treated with ABVD holds true over time, the search for noncarcinogenic combination therapy will be well worth the effort. Therapeutic options in cancer treatment currently are few, and the benefits of potentially carcinogenic chemotherapy and radiotherapy continue to outweigh the risks.

Effect on immunologic and other indices of adjuvant cytotoxic chemotherapy including melphalan in breast cancer

Thirty patients with histologically proven node-positive early breast cancer (Stage II) were treated by total mastectomy and axillary clearance and adjuvant chemotherapy regimens including melphalan for 1 year. These patients were studied sequentially, at 3-month intervals, for up to 2 years to assess effects of cytotoxic drugs on immune function, and to determine whether any changes in immune function were related to recurrence. All indices were in the normal range before chemotherapy. The most marked and long-lasting effects of chemotherapy were on numbers of circulating T-cells and B-cells. Mean counts +/- one standard error (X 10(6)/ml) for T-cells before and 12 months after stopping chemotherapy were 1.537 +/- 0.118 and 0.874 +/- 0.120 (P less than 0.01), and for B-cells 0.345 +/- 0.060 and 0.207 +/- 0.030 (P less than 0.01). Functional indices of T-cell and B-cell competence were less compromised than values for cell counts and, in contrast, recovery occurred either during or within 3 months of stopping chemotherapy. This held for both T-cell function measured by delayed-type hypersensitivity (DTH) responsiveness to five recall antigens and mitogenic responsiveness to phytohemagglutinin, and for B-cell function measured by titration of blood group isohemagglutinins. After 4 years the 30 subjects were divided into groups according to whether there was recurrence of cancer (14) or no recurrence (16); the only index predictive of recurrence was depression of DTH to recall antigens. Thus it was found that cytotoxic chemotherapy with melphalan appears to cause long-lasting depression of cell counts but only short-lasting depression of functional indices of immunocompetence, and that levels of immunologic indices during chemotherapy are mostly nonpredictive of recurrence of cancer. The results prompt some caution in the use of adjuvant chemotherapy, at least with melphalan.

Acute nonlymphocytic leukemia following treatment of malignant glioma. Report of two cases

Two patients with malignant brain tumors who developed acute nonlymphocytic leukemia after treatment with radiation and chemotherapy are described. Both patients survived more than 2 years after diagnosis of the brain tumor. Survival following the diagnosis of leukemia was short, and both patients died of hemorrhage secondary to thrombocytopenia. A review of the literature reveals that leukemia after combined-modality treatment of malignant brain tumors is rare. A prolonged survival period from diagnosis of the primary tumor, treatment with nitrosoureas and radiation, plus the development of a preleukemic myelodysplastic syndrome are all important features of therapy-related nonlymphocytic leukemia.

Carcinogenicity of antineoplastic agents in man

Review of the literature shows that: Anticancer drugs are in all probability mostly also carcinogenic. Alkylating agents such as melphalan, chlorambucil and cyclophosphamide seem to lead to the highest rate of second malignancies. Second malignancies after antitumour drugs are mostly acute leukaemias. Conditions which could influence the carcinogenicity of an antitumour drug are (a) its carcinogenic potency; (b) long-term administration; (c) the total dose used and (d) long-term survival of the patient. Irradiation and chemotherapy seem to have the greatest carcinogenic potential, e.g. in malignant lymphomas. The role of immunosuppression as a co-carcinogenic factor is difficult to estimate. Although transplant patients on anticancer drugs for immunosuppression have a higher risk of reticulosarcomas, but not of solid tumours, there is no evidence to suppose that in general immunosuppression and carcinogenicity are directly related. There is no reason to abandon intensive chemotherapy regimes if they lead to significant therapeutic results on the grounds of possible carcinogenicity of these drugs.

Bone marrow transplantation performed as first-time treatment in two cases of secondary acute myeloid leukemia

Two young patients with secondary acute myeloid leukemia were treated with allogeneic bone marrow transplantation as first-line treatment for their disease. High dose cytosine arabinoside was added to the conventional preparative regiment of cyclophosphamide and total body irradiation. No major problems were encountered to the immediate post-transplantation period. Complete remission of the acute myeloid leukemia was noted in both patients, with no evidence of recurrent disease at 15+ and 13 months. One patient developed severe pancytopenia 10 months after grafting with the presence of antibodies against platelets and granulocytes from the bone marrow donor. She died 3 months later from a generalised Aspergillus septicemia, probably precipitated by therapy with high doses of methylprednisolone. The other patient is alive in excellent clinical condition and in hematologic remission. Bone marrow transplantation must be taken into consideration as first-line therapy in any young patient who is suffering from a refractory type of leukemia and who has a suitable donor.

Acute transformation of chronic lymphocytic leukemia

A patient with chronic lymphocytic leukemia had typical cell morphology and a characteristic clinical course for 7 years. He then developed progressive disease with a rapidly rising WBC which proved resistant to chemotherapy. The cells resembled lymphoblasts. Immunoperoxidase studies demonstrated identical immunoglobulin light and heavy chains on the surface of both mature lymphocytes and lymphoblasts. Using a recently described monoclonal antibody, B5, a "blast" antigen was demonstrated on the lymphoblast cell surface, but not on the mature lymphocytes. On the basis of morphological and immunological studies, we suggest that the patient's malignant clone transformed from chronic lymphocytic leukemia to acute lymphoblastic leukemia.

Aggressive large cell lymphoma of the ileum after long-term cyclophosphamide therapy for breast carcinoma

A middle-aged woman was treated for breast carcinoma with postoperative adjuvant chest wall irradiation, followed four and seven years later with therapy to spinal ports for palliation of metastatic disease. For the next three and a half years, she received oral cyclophosphamide on a daily basis to a total of more than 110 g. Twelve years after diagnosis and five years after the start of chemotherapy, an aggressive, large cell lymphoma of the ileum developed, with poor response to conventional therapy. This may represent the first patient with breast carcinoma in whom a treatment-induced non-Hodgkin's lymphoma has developed.

Second neoplasms in acute lymphoblastic leukemia

The authors reviewed 61 reported cases of second neoplasms in acute lymphoblastic leukemia (ALL), including 17 patients with ALL followed by another type of acute leukemia, 12 patients with ALL followed by chronic myelocytic leukemia, 19 patients with ALL followed by lymphoma, and 13 patients with ALL followed by other solid tumors. From a review of the literature, it is believed that there is no firm evidence yet that patients with ALL, intensively treated with chemotherapy and/or radiotherapy, are at increased risk of developing therapy-related second neoplasms. Because the number of cases reported is small, there is even insufficient data to firmly suggest that acute myeloblastic leukemia, following intensive therapy for ALL, occurs in a higher-than-expected frequency.

Chemotherapy related leukemogenesis

Administration of aggressive chemotherapy to patients with cancer has considerably improved their outlook for effective palliation or cure. However, a hitherto unappreciated complication consisting of a secondary malignancy, in particular acute leukemia, has emerged. Prolonged therapy with alkylating agents and chemotherapy plus radiotherapy are associated with an increased risk of this complication. The disease evolves through a preleukemic phase of pancytopenia and sideroblastic refractory anemia. The median onset from the initiation of chemotherapy is about 5 years with an increasing incidence with time. Myelomonocytic, monocytic and erythroleukemia with atypical features and resistance to conventional therapy predominate. Hyploidy and aberrations involving chromosomes 5 and 7 are frequent. Alkylating agents are carcinogenic in laboratory animals. Although the pathway to leukemogenesis in humans is unknown, a multistep evolution is envisaged. This involves: 1) initiation through induction of errors in DNA, 2) promotion related to stem cell replication following chemotherapy-induced aplasia and 3) propagation related to immunosuppression. It is possible that, as in myeloproliferative disorders, an underlying tendency for leukemia is present in patients with cancer. This may be accentuated by chemotherapy, and more frequently observed due to the longer survival of such patients. The crucial role of chemotherapy in leukemogenesis is evident from data accumulated in non-malignant conditions such as rheumatoid arthritis.

Secondary treatment of polycythemia rubra vera with 6-thioguanine

6-thioguanine, an antimetabolite not potentiated by allopurinol, has been used in the treatment of 29 patients with polycythemia vera. All but two of the patients had been treated previously by venesection and/or radioactive phosphorus (32p) and/or alkylating agents. The usual dose was 40-160 mg daily alternate weeks according to individual response. The treatment period varied from 6-66 months (mean, 31 months). Of 27 evaluable patients 24 (89%) responded to treatment and at one year there was a significant fall in all blood count parameters. Seven patients relapsed while on treatment and four were withdrawn because of side effects. 6-thioguanine merits further evaluation in the management of polycythemia vera, particularly in those patients who have received large cumulative doses of 32p and/or alkylating agents and in whom an alternative mode of therapy is desirable.

Controversies in the therapy of acute myelogenous leukemia

In the past 10 years, there has been substantial progress in the treatment of patients with acute myelogenous leukemia. Intensive induction chemotherapy and consolidation chemotherapy have increased complete remission rates from 25 percent to more than 70 percent and have extended median survival from six months to more than two years. Attempts to prolong remission with maintenance chemotherapy, immunotherapy, and central nervous system prophylaxis have been less successful. Recent data suggest that the use of intensification chemotherapy or bone marrow transplantation in patients in remission may further reduce or eliminate residual leukemia. As a result of one or more of these advances an increasing proportion of patients, up to 25 percent in some series, are alive and free of disease three to five years following diagnosis. Most data indicate that some of these patients may be cured. In this article, we review the therapeutic interventions responsible for this substantial increase in survival in what was previously a uniformly fatal disease. Recent advances are discussed as are controversies in management and future directions.

Chronic idiopathic thrombocytopenic purpura (ITP): site of platelet sequestration and results of splenectomy. A study of 197 patients

51Cr-platelet kinetics study was performed in 197 patients with chronic ITP after corticosteroid therapy had failed to induce a long lasting remission. The incidence of splenic, spleno-hepatic, hepatic and diffuse platelet sequestration site was 58%, 17%, 6% and 19%, respectively. Splenic and spleno-hepatic sequestration sites were more frequent in patients less than 30 years old and in patients with a platelet count lower than 50 x 10(9)/1. 111 patients were splenectomized shortly after the study. Normalization of the platelet count was obtained more frequently in patients with splenic and spleno-hepatic sequestration than in the others. Labelled platelet sequestration site was the best predictor of the outcome of splenectomy. Platelet kinetics is a non-invasive investigation that should be performed early after the diagnosis of chronic ITP in all patients eligible for splenectomy.