Research on different compound combinations of Realgar-Indigo naturalis formula to reverse acute promyelocytic leukemia arsenic resistance by regulating autophagy through mTOR pathway

ETHNOPHARMACOLOGICAL RELEVANCE

In China, the Chinese patent drug Realgar-Indigo naturalis Formula (RIF) is utilized for the therapy of acute promyelocytic leukemia (APL). Comprising four traditional Chinese herb-Realgar, Indigo naturalis, Salvia miltiorrhiza, and Pseudostellaria heterophylla-it notably includes tetra-arsenic tetra-sulfide, indirubin, tanshinone IIa, and total saponins of Radix Pseudostellariae as its primary active components. Due to its arsenic content, RIF distinctly contributes to the therapy for APL. However, the challenge of arsenic resistance in APL patients complicates the clinical use of arsenic agents. Interestingly, RIF demonstrates a high remission rate in APL patients, suggesting that its efficacy is not significantly compromised by arsenic resistance. Yet, the current state of research on RIF's ability to reverse arsenic resistance remains unclear.

AIM OF THE STUDY

To investigate the mechanism of different combinations of the compound of RIF in reversing arsenic resistance in APL.

MATERIALS AND METHODS

The present study utilized the arsenic-resistant HL60-PMLA216V-RARα cell line to investigate the effects of various RIF compounds, namely tetra-arsenic tetra-sulfide (A), indirubin (I), tanshinone IIa (T), and total saponins of Radix Pseudostellariae (S). The assessment of cell viability, observation of cell morphology, and evaluation of cell apoptosis were performed. Furthermore, the mitochondrial membrane potential, changes in the levels of PMLA216V-RARα, apoptosis-related factors, and the PI3K/AKT/mTOR pathway were examined, along with autophagy in all experimental groups. Meanwhile, we observed the changes about autophagy after blocking the PI3K or mTOR pathway.

RESULTS

Tanshinone IIa, indirubin and total saponins of Radix Pseudostellariae could enhance the effect of tetra-arsenic tetra-sulfide down-regulating PMLA216V-RARα, and the mechanism was suggested to be related to inhibiting mTOR pathway to activate autophagy.

CONCLUSIONS

We illustrated that the synergistic effect of different compound combinations of RIF can regulate autophagy through the mTOR pathway, enhance cell apoptosis, and degrade arsenic-resistant PMLA216V-RARα.

Arsenic trioxide: applications, mechanisms of action, toxicity and rescue strategies to date

Arsenical medicine has obtained its status in traditional Chinese medicine for more than 2,000 years. In the 1970s, arsenic trioxide was identified to have high efficacy and potency for the treatment of acute promyelocytic leukemia, which promoted many studies on the therapeutic effects of arsenic trioxide. Currently, arsenic trioxide is widely used to treat acute promyelocytic leukemia and various solid tumors through various mechanisms of action in clinical practice; however, it is accompanied by a series of adverse reactions, especially cardiac toxicity. This review presents a comprehensive overview of arsenic trioxide from preclinical and clinical efficacy, potential mechanisms of action, toxicities, and rescue strategies for toxicities to provide guidance or assistance for the clinical application of arsenic trioxide.

Superiority of anthracycline-free treatment in standard-risk acute promyelocytic leukemia: A systematic review and comparative epidemiological analysis

BACKGROUND

Recent advances in the treatment of acute promyelocytic leukemia (APML) have seen unprecedented improvements in patient outcomes. However, such rapid growth in understanding often leads to uncertainty regarding superiority among candidate treatment regimens, especially when further scrutinized from an epidemiological perspective.

AIMS

The aim of this systematic review with epidemiological analysis was to identify and compare commonly utilized protocols for standard-risk APML with a particular focus on complete remission (CR), overall/disease-free survival (DFS), and reported adverse events.

METHODS AND RESULTS

Medline, Scopus, and CINAHL were interrogated to identify studies utilizing all-trans retinoic acid (ATRA) in addition to arsenic trioxide (ATO) and/or anthracyclines such as idarubicin (IDA) in the treatment of de-novo APML. After collation of studies, an epidemiological analysis was subsequently performed to compare protocols with regards to outcomes of interest using number needed to benefit (NNB) and number needed to harm (NNH) measures. Seventeen articles, describing 12 distinct trials, were included in the analysis. These trials made use of three unique protocols; CR rates were 94%-100% for ATO/ATRA regimens, 95%-96% for ATO/ATRA/anthracycline regimens, and 89%-94% for ATRA/anthracycline regimens. Epidemiological analysis demonstrated NNB for CR was 9.09 (ATO/ATRA vs. ATRA/IDA) and 20.00 (ATO/ATRA vs. ATO/ATRA/IDA), NNH for neutropenia was -3.45 (ATO/ATRA vs. ATRA/IDA), and NNH for infection was -3.13 (ATO/ATRA vs. ATRA/IDA) and -1.89 (ATO/ATRA vs. ATO/ATRA/IDA).

CONCLUSION

The ATO/ATRA regimen is superior to chemotherapy-containing protocols at inducing remission and promoting survival in patients with APML. The regimen is better tolerated than the proposed alternatives with fewer adverse events. Future research opportunities include quantifying APML epidemiology and pursuing oral arsenic as an option for simplification of therapeutic protocols.

Clinical Indicators of Hepatotoxicity in Newly Diagnosed Acute Promyelocytic Leukemia Patients Undergoing Arsenic Trioxide Treatment

Arsenic trioxide (ATO)-induced hepatotoxicity is often observed in acute promyelocytic leukemia (APL) patients and decreases therapeutic effect of ATO. Thus, concerns over hepatotoxicity have been raised. The aim of this study was to explore some noninvasive clinical indicators that can be used to guide the individualized application of ATO in the future. APL patients treated with ATO were identified retrospectively via electronic health records at our hospital from August 2014 through August 2019. APL patients without hepatotoxicity were selected as controls. The association between putative risk factors and ATO-induced hepatotoxicity was estimated with ORs and 95% CIs, which were calculated using the chi-square test. The subsequent multivariate analysis was performed using logistic regression analysis. In total, 58.04% of patients experienced ATO-induced hepatotoxicity during the first week. Elevated hemoglobin (OR 8.653, 95% CI, 1.339-55.921), administration of nonprophylactic hepatoprotective agents (OR 36.455, 95% CI, 7.409-179.364), non-single-agent ATO to combat leukocytosis (OR 20.108, 95% CI, 1.357-297.893) and decreased fibrinogen (OR 3.496, 95% CI, 1.127-10.846) were found to be statistically significant risk factors for ATO-induced hepatotoxicity. The area under the ROC curve values were 0.846 for "overall ATO-induced hepatotoxicity" and 0.819 for "early ATO-induced hepatotoxicity." The results revealed that hemoglobin ≥ 80 g/L, nonprophylactic hepatoprotective agents, and non-single-agent ATO and fibrinogen < 1 g/L are risk factors for ATO-induced hepatotoxicity in newly diagnosed APL patients. These findings can enhance the clinical diagnosis of hepatotoxicity. Prospective studies should be performed in the future to validate these findings.

Estimation of the Frequency and Time of Human Exposure to Arsenic by Single Hair Analysis

Arsenic (As) and its compounds are widely used in many applications. Long-term exposure to As can cause acute and chronic poisoning. In severe cases, it can lead to adverse effects, such as gene mutation, cell cancer and fetal malformation. The objective of this study was to accurately estimate As exposure frequency and time. Quantitative analysis of As in single hairs obtained from APL (acute promyelocytic leukemia) patients treated with As₂O₃ was performed by LA-ICP-MS. An informative As concentration distribution profile of single hair was applied to estimate the As exposure frequency and time. As exposure frequency was estimated according to the number of As concentration peaks. As exposure time was estimated according to the hair growth length in combination with the hair growth rate. The validation results demonstrate that this method was more efficient than the traditional method; compared with the traditional method, which provides estimates in months, our model shortened the As exposure time estimate to the range of a few days, which considerably improved the inference accuracy. Therefore, these results can be used for forensic toxicology studies, environmental exposure monitoring, etc.

Successful Treatment of Therapy-related Acute Promyelocytic Leukemia with All-trans-retinoic acid Following Epirubicin for Hepatocellular Carcinoma and Docetaxel and Pembrolizumab Therapies for Lung Carcinoma: A Triple Malignancy Case

A 69-year-old man was referred to the hematology department for the evaluation of pancytopenia. He had been treated with radiation and epirubicin for hepatocellular carcinoma, and with docetaxel and pembrolizumab for lung adenocarcinoma. Bone marrow smears exhibited markedly increased promyelocytes, and polymerase chain reaction (PCR) study demonstrated chimeric fusion genes of PML-RARA. He was diagnosed with therapy-related acute promyelocytic leukemia (t-APL) and treated with all trans-retinoic acid (ATRA). After 30 days of ATRA treatment, complete hematological response was achieved. To the best of our knowledge, this case represents the first description of successfully treated t-APL diagnosed after treatment with pembrolizumab.

Lentivirus‑mediated RIG‑I knockdown relieves cell proliferation inhibition, cell cycle arrest and apoptosis in ATRA‑induced NB4 cells via the AKT‑FOXO3A signaling pathway in vitro

Retinoic acid inducible gene I (RIG‑I) is upregulated during all‑trans retinoic acid (ATRA)‑induced terminal granulocytic differentiation of NB4 acute promyelocytic leukemia (APL) cells. However, the function and mechanism of RIG‑I in NB4 cells remains to be fully elucidated. In the present study, lentivirus‑mediated RIG‑I‑knockdown was used to investigate the proliferation, cell cycle and apoptotic processes of ATRA‑induced NB4 cells in vitro using an MTT assay and flow cytometry, respectively. The roles of RIG‑I and the AKT‑FOXO3A signaling pathway were investigated using western blot analysis. The results showed that the ATRA‑induced expression of RIG‑I was specifically and effectively knocked down at the mRNA and protein levels by lentivirus mediated RIG‑I short hairpin RNA. In addition, silencing of RIG‑I reduced the ATRA‑induced inhibition of NB4 cell proliferation, cell cycle arrest and apoptosis. Further investigations indicated that with ATRA‑induced expression of RIG‑I, levels of phosphorylated (p)AKT‑Thr308 and pForkhead Box (FOX) O3A‑Thr32 were decreased, the expression levels of cell cycle arrest protein p27 and the apoptotic protein, tumor necrosis factor‑related apoptosis‑inducing ligand (TRAIL), directly transcribed by FOXO3A were increased. By contrast, following the knockdown of ATRA‑induced expression of RIG‑I, the levels of pAKT‑Thr308 and pFOXO3A‑Thr32 were increased, and the protein expression levels of p27 and TRAIL were decreased. Taken together, these results showed that the knockdown of RIG‑I reduced the inhibition of cell proliferation, cell cycle arrest and apoptosis in the ATRA‑induced NB4 cells via the AKT‑FOXO3A signaling pathway.

Secondary acute promyelocytic leukemia following chemotherapy for gastric cancer: A case report

Therapy-related acute myeloid leukemia (t-AML) refers to a heterogeneous group of myeloid neoplasms that develop in patients following extensive exposure to either cytotoxic agents or radiation. The development of t-AML has been reported following treatment of cancers ranging from hematological malignancies to solid tumors; however, to our knowledge, t-AML has never been reported following treatment of gastric cancer. In this study, we report the development of t-acute promyelocytic leukemia in a cT4N1M0 gastric cancer patient after an approximate 44 mo latency period following treatment with 4 cycles of oxaliplatin (OXP) (85 mg/m² on day 1) plus capecitabine (1250 mg/m² orally twice daily on days 1-14) in combination with recombinant human granulocyte-colony stimulating factor treatment. Karyotype analysis of the patient revealed 46,XY,t(15;17)(q22;q21)[15]/46,idem,-9,+add(9)(p22)[2]/46,XY[3], which, according to previous studies, includes some “favorable” genetic abnormalities. The patient was then treated with all-trans retinoic acid (ATRA, 25 mg/m²/d) plus arsenic trioxide (ATO, 10 mg/d) and attained complete remission. Our case illuminated the role of certain cytotoxic agents in the induction of t-AML following gastric cancer treatment. We recommend instituting a mandatory additional evaluation for patients undergoing these therapies in the future.

Global characteristics of childhood acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) comprises approximately 5-10% of childhood acute myeloid leukemia (AML) cases in the US. While variation in this percentage among other populations was noted previously, global patterns of childhood APL have not been thoroughly characterized. In this comprehensive review of childhood APL, we examined its geographic pattern and the potential contribution of environmental factors to observed variation. In 142 studies (spanning >60 countries) identified, variation was apparent-de novo APL represented from 2% (Switzerland) to >50% (Nicaragua) of childhood AML in different geographic regions. Because a limited number of previous studies addressed specific environmental exposures that potentially underlie childhood APL development, we gathered 28 childhood cases of therapy-related APL, which exemplified associations between prior exposures to chemotherapeutic drugs/radiation and APL diagnosis. Future population-based studies examining childhood APL patterns and the potential association with specific environmental exposures and other risk factors are needed.

Late onset post-transfusion hepatitis E developing during chemotherapy for acute promyelocytic leukemia

We herein report the case of a leukemia patient who developed hepatitis E seven months after undergoing a transfusion with contaminated blood products. The latency period in this case was significantly longer than that of typical hepatitis E. Recently, chronic infection with hepatitis E virus (HEV) genotype 3 has been reported in immunocompromised patients. There is a possibility that our patient was unable to eliminate the virus due to immunosuppression following chemotherapy and the administration of steroids. The prevalence of HEV in healthy Japanese individuals is relatively high and constitutes a critical source of infection via transfusion. Hepatitis E is an important post-transfusion infection, and immunocompromised patients may exhibit a long latency period before developing the disease.

[Report of a case with secondary acute promyelocytic leukemia after therapy for hemophagocytic lymphohistiocytosis and review of literature]

OBJECTIVE

To explore the characteristics and risk of etoposide-related leukemia in the treatment of hemophagocytic lymphohistiocytosis (HLH).

METHOD

Clinical characteristics of a case with secondary acute promyelocytic leukemia (APL) were summarized and 10 cases of secondary leukemia after treatment for HLH from literature were analyzed.

RESULT

The child was diagnosed with Epstein-Barr virus associated HLH and received HLH-2004 protocol. The cumulative dose of etoposide (VP16) was 3520 mg/m(2). The patient was diagnosed with APL after 28 months of HLH.He achieved complete remission after induction chemotherapy of all-trans-retinoic acid and darubicin. Consolidated chemotherapy was continued. There were 10 reports of etoposide-related leukemia after treatment for HLH in the literature.Review of 11 cases treated with VP16, of which cumulative doses were 900-20 500 mg/m(2). The interval period between HLH and secondary leukemia was 24 months. The types of secondary leukemia included 1 case with acute lymphoblastic leukemia, 1 case with myelodysplastic syndrome and 9 cases of acute myeloid leukemia. The abnormalities of chromosome included 3 patients with 11q23, 3 APL patients with t (15, 17).Seven patients survived and 4 died.

CONCLUSION

The latency period of etoposide-related leukemia is short. Acute myeloid leukemia and balanced chromosomal abnormality are common in etoposide-related leukemia. The risk factors for development of secondary leukemia are related to cumulative drug doses of etoposide, treatment schedules and co-administration of other antineoplastic agents.It is appropriate to keep suitable range of the cumulative dose of etoposide in HLH therapy in order to reduce the risk of therapy related leukemia.

Mitoxantrone-related acute leukemia in two MS patients

We report two new cases of mitoxantrone-related leukemia occurring in two patients with multiple sclerosis (MS), 14 and 18 months after the last infusion of the drug. One patient was successfully treated. We were able to collect 29 other cases in the literature. Most of them were single reports but some were described within cohorts of mitoxantrone-treated MS patients. The incidence rate was 0.65% from all cohorts totalizing 2299 patients. Acute promyelocytic leukemia with the translocation t(15;17) was over-represented in the MS population in comparison with cancer patients also treated with mitoxanrone. The occurrence of leukemia was dose-independent and appeared with a mean delay of 20 months after the end of the treatment.

[Gemtuzumab ozogamicin successfully induced molecular remission in relapsed therapy-related acute promyelocytic leukemia]

A 37-year-old woman was diagnosed with therapy-related acute promyelocytic leukemia (t-APL) in May 2006 after chemotherapy that included etoposide for ovarian cancer in November 2003. After treatment with all-trans retinoic acid in combination with chemotherapy, complete remission was attained. The patient was admitted on March 19, 2007 due to cerebral infarction and it was found that t-APL had recurred. Induction therapy with gemtuzumab ozogamicin (GO) was attempted. Molecular remission was attained without serious complication. GO is considered a promising agent to achieve molecular remission in patients with relapsed t-APL.

Long-term colchicine therapy in a patient with Behçet’s disease and acute promyelocytic leukemia

Behçet's disease causes a continuous T-lymphocytic mediated inflammatory reaction in the small arterioles, which results in gradual destruction of any human organ or system. The benefit of treatment with colchicine in patients with Behçet's disease has been reported in literature. Acute leukemia has seldom been associated with Behçet's disease, although acute promyelocytic leukemia is a particular subtype of leukemia that is often characterized by special cytogenetic abnormalities. We report a male patient with acute promyelocytic leukemia and Behçet's disease who had received long-term treatment with colchicine. To our knowledge, this is the first report of the concomitant occurrence of acute promyelocytic leukemia and Behçet's disease, which suggests that long-term colchicine therapy has a role in the pathogenesis of acute promyelocytic leukemia. The patient described has been treated with retinoic acid and idarubicin (the ATRA-IDA protocol). At the time of this writing, his disease is in clinical remission.

Clustered incidence of acute promyelocytic leukemia during gefitinib treatment for non-small-cell lung cancer: experience at a single institution

Although gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, has been shown a significant activity for recurrent non-small-cell lung cancer (NSCLC), its long-term adverse effect with its continuous usage has hitherto not been clearly elucidated. Subjects were 108 consecutive NSCLC cases who were treated with gefitinib between November 2001 and December 2004 at our single institution. A crude incidence rate ratio was calculated by ratio of crude incidence rate in our subject to population-based incident rate of all leukemia (ICD: C91-95) in the same region. The 95% confidence intervals (CIs) were calculated based upon a Poisson distribution. Three cases of acute promyelocytic leukemia (APL) occurred during gefitinib treatment, and these patients' past treatment histories are presented herein. No other malignancy was identified. All of the cases were diagnosed at the stage of mild-to-moderate cytopenia, especially thrombocytopenia, without disseminated intravascular coagulation. All presented a normal karyotype with positive PML-RARalpha in RT-PCR, indicating submicroscopic translocation. They responded well to APL treatments, including all-trans-retinoic acid. The crude incident rate ratio was 639.9 (95% confidence interval: 131.6-1,878.9, P < 0.0001) when the APL incidence in this cohort was compared to all leukemia cases in the general population in the same district in Japan. Thus we had three cases of secondary APL patients within the gefitinib-treated NSCLC cohort. Although we cannot exclude an effect of past exposure of other cytotoxic agents and radiotherapy as a cause of APL, APL inducibility of gefitinib should be clarified in the further study.

[Complication of topoisomerase II inhibitor-related acute promyelocytic leukemia with t(1;10) (q21;q26) in a patient with Sézary syndrome]

A 74-year-old man was diagnosed as having Sézary syndrome in 1999. Treatment with combination chemotherapy could not completely control both the erythroderma and Sézary cells. However, treatment with oral administration of etoposide was able to maintain the patient in a good condition for about 4 years. In June 2004, he developed topoisomerase II inhibitor-related acute promyelocytic leukemia. Chromosomal analysis demonstrated abnormalities of t(1;10) (q21;q26) and t(15;17) (q22;q12) in 17 of 20 cells. Despite treatment with ATRA and combination chemotherapy, the patient died of brain hemorrhage.

[Therapy-related acute promyelocytic leukemia with a t(9;22)(q34;q11) and t(15;17)(q22;q11 to approximately 12) subclone]

The translocation (15;17) is a typical marker of acute promyelocytic leukemia, whereas t(9;22) is predominantly associated with chronic myelogenous leukemia, and seldom with acute myelogenous leukemia. Furthermore, the association between t(15;17) and t(9;22) in the same cell is extremely rare. We present a case of therapy-related acute promyelocytic leukemia (t-APL) with a subclone accompanied by karyotype 46, XX, t(9; 22)(q34;q11), t(15 ;17)(q22;11 to approximately 12) at onset. A 75-year-old woman was diagnosed as having non-Hodgkin lymphoma of the thyroid gland in July 1997. She was treated with a CHOP-like regimen, but complete remission (CR) was not achieved. She then underwent surgical resection of her thyroid gland, and was treated with etoposide (total dose 16775 mg) from February 1998 to May 2000. In June 2000, having developed t-APL, she was referred to our department. The patient attained CR following treatment with chemotherapy containing all-trans retinoic acid. Ten months later she relapsed, but lost the t(9;22), while maintaining the t(15;17).

Apoptotic effect of oridonin on NB4 cells and its mechanism

The anti-proliferation effects of oridonin on acute promyelocytic leukemia (APL) cells and its mechanisms were studied in vitro. NB4 cells as well as fresh leukemia cells obtained from APL patients in culture medium were treated with different concentrations of oridonin. Cell growth inhibition, apoptosis and related pathways were assessed by MTT assay as well as flow cytometry (FCM) and western blot analysis. The data revealed that oridonin (over 16 micromol/L) could inhibit the growth of NB4 cells by induction of apoptosis. Marked changes of cell apoptosis were observed very clearly by using electron microscopy and DNA fragmentation analysis after the cells exposed to oridonin for 48 h; Western blotting showed cleavage of the caspase-3 zymogen protein (32-kDa) with the appearance of its 20-kDa subunit as well as a cleaved 89-kDa fragment of 116-kDa PARP when apoptosis occurred. The expression of Bcl-2 was down-regulated remarkably accompanied by the disruption of the mitochondrial membrane potential (delta(psi)m). The anti-proliferative and apoptosis-inducing effects by oridonin in fresh APL cells were also found remarkably using Trypan Blue dye exclusion method and Wright's staining. We concluded that oridoning has significant anti-proliferative and apoptosis-inducing effects on NB4 cells by activation of caspase-3 and cleavage of PARP as well as by down regulation of Bcl-2 and disruption of the delta(psi)m. Furthermore, oridonin demonstrated apparent cell growth inhibition effects on fresh APL cells in vitro. The results indicated that oridonin may serve as a potential anti-leukemia reagent.

Acute Promyelocytic Leukemia After Iodine-131 Therapy for Graves' Disease

Graves' disease is an autoimmune process in which the thyroid gland is stimulated by autoantibodies, leading to hyperthyroidism. Graves' disease is the most common cause of hyperthyroid function, primarily affecting women in their 40s and 50s. Treatment may involve oral radioiodine, which is taken up by the follicular cells of the thyroid, where it emits ionizing radiation to promote destruction of those cells. Radioiodine therapy is typically safe, effective, and inexpensive. We describe the case of a 51-year-old woman who developed acute promyelocytic leukemia within 27 months of completing a cumulative dose of radioiodine 22.1 mCi (817.7 MBq) for treatment of Graves' disease. Assessment of causality using the Naranjo probability scale showed that a possible relationship existed between this patient's acute promyelocytic leukemia and the use of radioiodine. Strict hematologic follow-up of patients treated with radioiodine may be warranted, along with a high index of suspicion in those with coagulopathy.

Acute myeloid leukaemia induced by mitoxantrone: case report

Mitoxantrone (MX) is an immunosupressant drug used in secondarily progressive multiple sclerosis (SPMS) and in relapsing-remitting multiple sclerosis (RRMS). It has a leukemogenesis potential induced by cytogenetic abnormalities, though with a low incidence. Promyelocitic leukaemia (type M3) and other forms of acute myeloblastic leukaemias (M4 and M5) have been described in a few MS patients who received MX during their treatment. We describe a white female patient, 47 year-old, with SPMS (EDSS = 4) with 14 years of disease. She received MX during her disease and developed acute promyelocytic leukaemia (M3), with severe thrombocytopenia 30 months later. She ultimately died due to intracerebral hemorrhage. Other cases of treatment related to AML are reviewed and discussed.

DNA topoisomerase II in therapy-related acute promyelocytic leukemia

BACKGROUND

Chromosomal translocations leading to chimeric oncoproteins are important in leukemogenesis, but how they form is unclear. We studied acute promyelocytic leukemia (APL) with the t(15;17) translocation that developed after treatment of breast or laryngeal cancer with chemotherapeutic agents that poison topoisomerase II.

METHODS

We used long-range polymerase chain reaction and sequence analysis to characterize t(15;17) genomic breakpoints in therapy-related APL. To determine whether topoisomerase II was directly involved in mediating breaks of double-stranded DNA at the observed translocation breakpoints, we used a functional in vitro assay to examine topoisomerase II-mediated cleavage in the normal homologues of the PML and RARA breakpoints.

RESULTS

Translocation breakpoints in APL that developed after exposure to mitoxantrone, a topoisomerase II poison, were tightly clustered in an 8-bp region within PML intron 6. In functional assays, this "hot spot" and the corresponding RARA breakpoints were common sites of mitoxantrone-induced cleavage by topoisomerase II. Etoposide and doxorubicin also induced cleavage by topoisomerase II at the translocation breakpoints in APL arising after exposure to these agents. Short, homologous sequences in PML and RARA suggested the occurrence of DNA repair by means of the nonhomologous end-joining pathway.

CONCLUSIONS

Drug-induced cleavage of DNA by topoisomerase II mediates the formation of chromosomal translocation breakpoints in mitoxantrone-related APL and in APL that occurs after therapy with other topoisomerase II poisons.

[Myeloproliferative disorders due to the use of gasoline as a solvent: report of three cases]

BACKGROUND

Health effects of occupational exposure to benzene are currently a problem, despite the fact that preventive measures have been in existence in Italy for more than 40 years.

OBJECTIVES

To describe three recent cases of severe haematological disease presumably induced by an occupational exposure to benzene. Exposure occurred as a result of contact with ordinary automobile petrol used as a solvent-degreaser for metal parts.

METHODS

Clinical diagnosis was performed using standard immuno-phenotypic and morphological criteria; the hypothesis of an occupational origin was derived from analysis of the occupational histories.

RESULTS

The first case was a 59 year-old blacksmith suffering from acute myeloid leukaemia (AML) FAB M2, who had used petrol for 36 years to degrease the forged metal parts before painting them. The second was a 53 year-old mechanic with AML FAB M3 who had used petrol for 15 years to degrease mechanical parts of tanker motors. The third was an 82 year-old car mechanic suffering from idiopathic myelofibrosis since the age of 75, who had used petrol to degrease mechanical car motor parts for 42 years. In all three cases, the environmental hygiene measures necessary to limit inhalation or skin contact were not followed and, at times, in the case of the two mechanics, the petrol was siphoned by mouth; so there was substantial exposure to the 1-5% benzene present in the petrol. Latency of the disease was between 30-50 years from start of exposure, and between 3-17 years following cessation of exposure.

CONCLUSION

The cases described indicate that the myelotoxic effects of benzene are still a problem. They were the consequence of improper use of petrol, due to total misinformation of the risks involved in such use. It is not possible to ascertain whether the cases presented are a casual aggregation or if the use of petrol as a solvent is more common than is normally believed; in the latter case two questions must be asked: is a "normal" occupational history able to discover such an uncommon risky condition of exposure? If it cannot, how many cases of benzene-related diseases escape aetiological diagnosis? It is not possible to provide precise answers but efforts should be made to improve the quality of information about the risks of petrol. Furthermore, in all cases of haematological disease potentially related to benzene, any form of contact with petrol, even if uncommon, should be carefully researched.

Secondary acute leukemia following mitoxantrone-based high-dose chemotherapy for primary breast cancer patients

The incidence of secondary myelodysplasia/acute myeloid leukemia (AML) was retrospectively assessed in an international joint study in 305 node-positive breast cancer patients, who received mitoxantrone-based high-dose chemotherapy (HDCT) followed by autologous stem cell support as adjuvant therapy. The median age of the patients was 57 years (range 22-67). In all, 268 patients received peripheral blood stem cells, and 47 patients received autologous bone marrow. After a median follow-up of 57 months (range 10-125), three cases of secondary AML (sAML) were observed, resulting in a cumulative incidence of 0.94%. One case of sAML developed 18 months after HDCT (FAB M3) The karyotype was translocation 15;17 and, after induction therapy, the patient underwent autologous stem cell transplantation, and is in complete remission (CR) of both breast cancer and AML. The second patient developed AML (FAB M4eo with inversion 16) 5 months after HDCT. This patient achieved CR after induction therapy, but died of infectious complication. A third patient developed AML (FAB M4) 6 months after HDCT. She achieved CR after induction therapy, but relapsed and expired 28 months after diagnosis of AML. sAML after mitoxantrone-based HDCT is a possible, but rare complication in breast cancer patients.

Platinum compounds and therapy related acute promyelocytic leukemia

Therapy related acute promyelocytic leukemia (ta-APL) is a rare complication of chemotherapy for other malignant tumors. We report two such cases, one of whom was exposed only to carboplatin two years before developing ta-APL and the other one was treated with cisplatin, etoposide and bleomycin five years prior to developing ta-APL.

Two cases of therapy-related acute promyelocytic leukemia (t-APL) after mantle cell lymphoma and gestational trophoblastic disease

We report two cases of secondary acute promyelocytic leukemia (APL). One patient presented with concurrent APL and missed abortion 1 year after etoposide-based chemotherapy for gestational trophoblastic disease. A prolonged complete remission was achieved with standard chemotherapy. An elderly man developed APL 1 year after alkylator-based chemotherapy for mantle cell lymphoma (MCL). A complete clinical and molecular remission was obtained with chemotherapy and all- trans retinoic acid, followed by arsenic consolidation. Concomitant molecular relapse of APL and MCL clones was detected at 1 year, both of which responded to oral arsenic therapy. High-dose epipodophyllin is a dose risk for secondary APL, but alkylating agents may also be implicated. For patients with a history of active malignancy and heavy previous chemotherapy exposure, the use of nontoxic arsenic therapy appeared to be effective and prudent.

t(1;3)(p36;p21) is a recurring therapy-related translocation

Chromosome bands 1p36 and 3p21 are known to be recurring breakpoints in therapy-related (t-) leukemia. We identified a recurring translocation, t(1;3)(p36;p21), in eight patients with various hematologic malignancies: three patients with ALL, one with chronic myelogenous leukemia (CML) in accelerated phase (AP), two with MDS, and two with AML(M3). Five of the eight patients had a history of chemotherapy, including alkylating agents in three, before the translocation was detected. In two of these five patients, the t(1;3)(p36;p21) emerged only at relapse or in the accelerated phase of CML. The karyotypes of the patients were complex, including -7 and structural abnormalities of 5q, 6q, 7q, 9p, and 11q23. Survival time varied among patients (25 days to more than 16 years). Using FISH with 13 1p35-36 cosmid probes (tel-FB12-CA5-G7-FD2-CB1-ED8-FD9-G32-AE3-G50-AD8-GG4-G43-cen), we delineated the 1p36 breakpoint in two patients with MDS and ALL as lying between FB12 and FD2 (between BAC47P3 and PAC963K15), with a small deletion near the breakpoint in both cases. In the patient with MDS, there was also a deletion at 3p21.3, as detected with the cosmid probe cosNRL9. The results of the present study suggest that t(1;3)(p36;p21) in hematologic diseases is associated with prior exposure to mutagens, including alkylating agents.

Pregnancy after treatment of secondary acute promyelocytic leukemia following Hodgkin's disease: a case report

The authors report a case of therapy-related acute promyelocytic leukemia (t-APL), with typical cytogenetic translocation t(15;17), which appeared following chemotherapy (ABVD), and radiotherapy for Hodgkin's disease (IIB). After treatment with all-trans retinoic acid (Vesanoid(R) 45 mg/m2 daily) complete remission of t-APL was achieved. Then only one course of chemotherapy '3+7' (doxorubicin 45 mg/m2 1-3 d, cytosar 200 mg/m2 1-7d) was applied and the patient interrupted further treatment in July 1994. Four years later she had a normal pregnancy and delivered a healthy female infant in December 1998.

Acute promyelocytic leukemia after treatment for non-Hodgkin's lymphoma with drugs targeting topoisomerase II

We report a patient who developed acute promyelocytic leukemia (APL) concomitantly with a second relapse of non-Hodgkin's lymphoma (NHL), intermediate grade, WF type E. At diagnosis and at first NHL relapse, the patient had received the same chemotherapy regimen, which included drugs targeting DNA topoisomerase II, i.e., etoposide (total dose 5,760 mg) and idarubicin (total dose 180 mg). Thirty-eight months after initial treatment, the patient showed pancytopenia associated with lymphoma recurrence. Bone marrow examination revealed the presence of atypical promyelocytes with Auer rods; cytogenetics showed t(15;17), and molecular analysis detected promyelocytic leukemia-retinoic acid receptor alpha rearrangement. APL reached complete remission after all trans retinoic acid therapy, whereas NHL did not respond to further chemotherapy. In the literature, five other patients developed APL after treatment for lymphoma, from a total of 59 patients developing sAPL after treatment for any type of neoplasia.

[Leukemia associated with bimkolane]

Psoriatic patients and mice treated with bimolane were observed. The frequency of chromosomes aberration and micro-nuclear cells presence in the treated group (11 cases) was significantly higher than that in the control group (11 cases, P < 0.005; < 0.001). Study of lymphocytic subsets showed that value of CD4/CD8 in the peripheral blood of the treated group was lower than that of the control group (P < 0.05). The level of serum IgM in the treated group was also lower (P < 0.05). There were 10 mice suffering from leukemia (7 mice with acute promyelocytic leukemia) in a treated group of 40 mice of an inbred line of 615 mice, while there was no leukemia in a control group of 20 mice of the same species. The morbidity of leukemia in the treated mice was higher than that of controls (P < 0.05).