Differentiation of t(5;17) variant acute promyelocytic leukemic blasts by all-trans retinoic acid

All-trans retinoic acid (ATRA) induces differentiation of acute promyelocytic leukemic (APL) blasts from patients with t(15;17) APL. However, blasts from patients with the t(11;17) variant do not differentiate in response to ATRA. Our group has identified a variant of APL characterized by t(5;17) and expression of the NPM-RAR fusion gene product. From case reports it has been difficult to establish whether ATRA induces clinical responses in patients with this variant. In order to determine whether t(5;17) blasts differentiate with ATRA, we harvested mononuclear bone marrow cells from a patient with t(5;17) APL at time of relapse and cultured them in medium containing ATRA. Morphologic analysis of cytospins after 7 days of culture revealed that 60% of cells in the ATRA-treated culture had differentiated into mature neutrophilic forms, as opposed to less than 1% in the control culture. Seventy-three percent of cells acquired NBT positivity after exposure to ATRA, compared with 1% in the control culture. These results indicate that t(5;17) blasts retain the ability to terminally differentiate in response to retinoic acid.     

Ultrastructural observations on a variant of acute promyelocytic leukemia

A patient with acute leukemia is presented in whom the leukemic cells, as seen by light microscopy were typical promyelocytes. The cells had normal or slightly invaginated nuclei with typical cytoplasmic granules and the diagnosis was confirmed by cytochemistry. The clinical course was rapid and the patient died of disseminated intravascular coagulation and urosepsis within a few days of diagnosis. However, electron microscopic examination showed cells with extremely convoluted and lobulated nuclei with nuclear pockets and cytoplasmic bridges as well as the complete absence of cytoplasmic granules in the majority of the cells. Furthermore, the urine lysozyme (muramidase) was elevated. These findings suggest that the leukemia in this patient may be classified as a hypogranular variant of acute promyelocytic leukemia (APL), with monocytoid ultrastructural appearances.     

The t(14;18) in a patient with de novo acute lymphoblastic leukemia is associated with t(8;9)

Cytogenetic analysis of a bone marrow aspirate from a patient with acute lymphoblastic leukemia (ALL) revealed the presence of a complex karyotype containing the translocation, t(14;18)(q32;q21). Further investigations using fluorescence in situ hybridization (FISH) allowed the characterization of an additional translocation, t(8;9)(q24;p1?). The association of t(14;18)(q32;q21) and t(8;9)(q24;p13) has recently been described in two patients with de novo ALL (Nacheva et al. Blood 1993;82:231-240) and this report supports these findings.     

Use of trans-retinoic acid in the treatment of acute promyelocytic leukemia

OBJECTIVE: To discuss acute promyelocytic leukemia (APL) and review the literature concerning differentiation treatment of APL with trans-retinoic acid (t-RA). DATA SOURCES: English-language articles concerning APL or its treatment with t-RA were identified with a MEDLINE search. STUDY SELECTION: All studies available at the time of article preparation, which addressed t-RA treatment in APL, were selected. DATA EXTRACTION: Data extraction and assessment were performed subjectively by the authors. An extensive discussion of specific study details is included in the article. DATA SYNTHESIS: APL is a unique subset of acute myelogenous leukemia and is typified by an accumulation of malignant promyelocytes in the bone marrow. Within the granulocyte cell cycle of a patient with APL, differentiation has been halted at the level of the promyelocyte, preventing formation of mature granulocytes. Upon treatment with traditional cytotoxic chemotherapy, complete remission rates of approximately 70 percent, with a five-year survival ranging from 25 to 40 percent have been achieved. In most patients with APL, a characteristic chromosomal t(15q+;17q-) translocation has been found, which may be responsible for the production of an aberrant retinoic acid receptor-alpha. Therefore, t-RA induction therapy has been investigated and has produced promising results. Administration of t-RA in dosages of 45-100 mg/m2/d has induced complete remissions. The apparent mechanism of t-RA is the induction of promyelocyte differentiation and maturation. The most common adverse effects noted have been dry skin, cheilitis, and headaches. CONCLUSIONS: Upon consideration of the initial trials, t-RA appears to be a promising and unique treatment for APL.     

Phenotypic conversion from t(8;21) acute myeloid leukemia to MLL gene rearrangement-positive acute lymphoblastic leukemia

Phenotypic conversion from acute myeloid leukemia (AML) to acute lymphoblastic leukemia (ALL) is rare. A 38-year-old man was initially diagnosed as having AML (FAB-M2) associated with the t(8;21)(q22;q22) chromosomal abnormality. The blasts showed myeloperoxidase (MPO) activity and CD13 antigen expression. He showed complete remission after standard chemotherapy for AML. However, the patient relapsed with blasts showing ALL morphology (FAB-L1), MPO negativity, and CD19 antigen expression 33 months after cessation of AML therapy. Cytogenetic analysis at relapse was unsuccessful. Molecular analysis of ALL blasts revealed immunoglobulin heavy-chain gene and MLL gene rearrangements but no AML1 gene. MLL gene rearrangement or the 11q23 chromosomal abnormality has been associated with therapy-related leukemia. The subsequent ALL in our patient may have been induced by the chemotherapy including daunorubicin, known as a topoisomerase II inhibitor.     

Terson''s syndrome in a patient with acute promyelocytic leukemia on all-trans retinoic acid treatment

Hypothermia induced by surface cooling has shown to protect vulnerable regions of the brain during an ischemic insult. This study evaluated the neuroprotective efficacy of neurotensin, a potent hypothermic agent, using a 5-min carotid occlusion procedure in the gerbil. In Experiment 1, the dose-response and time course of neurotensin-induced hypothermia were evaluated (n = 5/dose). Central infusion of 10, 20, and 30 micrograms neurotensin were found to significantly decrease core body temperature of conscious gerbils within 30 min of administration. In Experiment 2, gerbils pretreated with 30 micrograms neurotensin were permitted to become hypothermic or were maintained at 37 degrees-38 degrees C (rectal) during ischemic insult. Other gerbils were pretreated with peptide vehicle prior to ischemic insult (at 37 degrees -38 degrees C) or underwent a sham procedure (n = 6/condition). At 24 h after surgery, gerbils were tested for increased locomotor activity in an open-field apparatus. Gerbils pretreated with peptide vehicle or neurotensin and maintained at 37 degrees-38 degrees C during ischemia had significantly higher activity levels compared to the other treated groups. In contrast, gerbils made hypothermic with neurotensin exhibited activity levels similar to sham gerbils. Histological assessment revealed that neurotensin-induced hypothermia protected the CA1 region from ischemic damage.     

Caspases mediate retinoic acid-induced degradation of the acute promyelocytic leukemia PML/RARalpha fusion protein

All-trans-retinoic acid (RA) treatment induces morphological remission in acute promyelocytic leukemia (APL) patients carrying the t(15;17) and expressing the PML/RARalpha product by inducing terminal differentiation of the leukemic clone. RA treatment induces downregulation of PML/RARalpha and reorganization of the PML-nuclear bodies. These events have been proposed to be essential for the induction of APL cell differentiation by RA. Here, we show that in the APL-derived NB4 cell line as well as in myeloid precursor U937 cells expressing the PML/RARalpha (U937/PR9) and in blasts from APL patients, the PML/RARalpha fusion protein is cleaved by a caspase 3-like activity induced by RA treatment. In fact, a caspase 3-like activity is detectable in PML/RARalpha expressing cells after RA treatment, and selective caspase inhibitor peptides are able to prevent the RA-induced degradation of the fusion protein in vivo and in vitro. Using recombinant caspases and PML/RARalpha deletion mutants we mapped a caspase 3 cleavage site (Asp 522) within the alpha-helix region of the PML component of the fusion protein. The extent of PML/RARalpha cleavage directly correlates with the ability of RA to restore the normal PML nuclear bodies (NBs) pattern. However, RA-induced differentiation is not prevented by the persistence of the fusion product and occurs in the absence of normally structured PML NBs. These results indicate that PML/RARalpha is directly involved in conferring RA sensitivity of APL cells and that the RA-induced reassembly of PML NBs is the consequence of the disappearance of PML/RARalpha.     

B-cell acute lymphoblastic leukemia with L1 morphology and coexistence of t(1;19) and t(14;18) chromosome translocations

We report a case of adult de novo acute lymphoblastic leukemia (ALL) with unique cytogenetic abnormalities and discrepant morphologic and immunologic features. Morphology was L1 by the French-American-British classification, but flow cytometry was consistent with a mature B-cell phenotype. Cytogenetic analysis showed numerous chromosome abnormalities nonspecific for lymphoid neoplasm except for t(1;19) and t(14;18). The former is characteristic of pre-B-ALL and the latter is characteristic of follicular lymphoma. This is the first report of these two translocations occurring concurrently in ALL.     

Sweet's syndrome during treatment with all-trans retinoic acid in a patient with acute promyelocytic leukemia

A 46 year old male with acute promyelocytic leukemia treated with all-trans retinoic acid (ATRA), developed fever, bilateral erythematous nodules in his axillary area, lower abdomen and inguinal region. Histopathologic examination of the skin biopsy revealed dense neutrophil infiltration in the dermis without vasculitis. The diagnosis of Sweet's syndrome was made. High dose methylprednisolone was administered and the lesions started to improve within 24 hours.     

t(8;21)急性髓系白血病患者MICM分型及预后的回顾性分析

目的 分析t(8;21)急性髓系白血病(AML)患者的细胞形态学、免疫表型、遗传学、分子生物学(MICM)分型及临床治疗疗效.方法 运用瑞特染色法、FAB细胞形态分类标准、流式细胞术(FCM)直接免疫荧光标记技术、遗传学染色体吉姆萨显带技术及RT-PCR技术对70例确认有t(8;21)与AML1-ETO融合基因双阳性的AML患者及70例正常染色体核型的AML患者进行分析和比较.结果 70例t(8;21)AML患者中M11例,M2 64例,M4 3例,无法分型的急性白血病(AL)2例;免疫表型分析发现CD13、CD33、CD34、CD117高表达,40%表达CD19,11%表达CD15,10%表达CD11b,7%表达CD7;遗传学显示50%的t(8;21)AML患者有附加染色体异常,主要为性染色体丢失、9q-及超二倍体;RT-PCR检测AML1-ETO融合基因100%阳性.CD+19t(8;21)AML患者完全缓解(CR)率72%,CD+19伴CD+7t(8;21)AML患者CR率为0,正常核型CR率31%.结论 t(8;21)AML患者主要在M2中集中出现,附加染色体异常较多见.CD19表达较高,而CD7表达极低,CD34、CD117高表达,这些抗原的表达可能与核型密切相关.CD+19是预后良好的指标,但同时出现CD+7,则预后不良.     

The PML/RAR alpha oncoprotein is a direct molecular target of retinoic acid in acute promyelocytic leukemia cells

Acute promyelocytic leukemia (APL) is characterized by the translocation, t(15;17) and the expression of a PML/RAR alpha fusion protein that is diagnostic of the disease. There is evidence that PML/RAR alpha protein acts as a dominant negative inhibitor of normal retinoid receptor function and myeloid differentiation. We now show that the PML/RAR alpha fusion product is directly downregulated in response to retinoic acid (tRA) treatment in the human APL cell line, NB4. tRA treatment induces loss of PML/RAR alpha at the protein level but not at the level of mRNA, as determined by Northern blots, by Western blots, and by ligand binding assays and in binding to RA-responsive DNA elements. We present evidence that this regulation is posttranslational. This evidence suggests that tRA induces synthesis of a protein that selectively degrades PML/RAR alpha. We further show that this loss of PML/ RAR-alpha is not limited to the unique APL cell line. NB4, because PML/RAR alpha protein is selectively downregulated by tRA when expressed in the transfected myeloid cell line U937. The loss of PML/RAR alpha may be directly linked to tRA-induced differentiation, because in a retinoid-resistant subclone of NB4, tRA does not decrease PML/RAR alpha protein expression. In NB4 cells, the specific downregulation of the fusion protein decreases the ratio of PML/RAR alpha to wild-type RAR alpha. Because the ratio of expression of PML/RAR alpha to wild-type RAR alpha and PML may be important in maintaining the dominant negative block of myelocytic differentiation, these data suggest a molecular mechanism for restoration by tRA normal myeloid differentiation in APL cells.     

Complete remission in acute promyelocytic leukemia. The advantages of all-trans-retinoic acid compared to conventional chemotherapy

In all of seven patients (six men, one woman; mean age 43 [24-55] years) with newly diagnosed acute promyelocytic leukaemia, treated between 1989 and 1993, complete remission was achieved. In three of these patients, treated between 1989 and 1991, remission was induced with conventional chemotherapy (cytarabine and anthracycline), after this in four patients with all-trans retinoic acid (tretinoin). The seventh patient who had a very rapid increase in leucocytes during tretinoin administration, was as a precaution also given conventional chemotherapy. All seven patients received consolidating chemotherapy with an intensive treatment cycle. Retrospective analysis indicated that induction with tretinoin had marked advantages: quicker regression of the clotting abnormalities (mean of 9 vs 25 days), shorter period of leukopenia (mean of 3.5 vs 30 days), shorter time until complete remission (mean of 38 vs 48 days). There were no specific side effects ascribable to tretinoin. Toxicity after chemotherapy corresponded to WHO grades 2-4. The results indicate that tretinoin markedly reduces the two main risks in the treatment of acute promyelocytic leukaemia: bleeding and infection.