Treatment of acute promyelocytic leukemia--combined use of all-trans retinoic acid and granulocyte colony-stimulating factor

We evaluated the effect of treatment by all-trans retinoic acid (ATRA) in 9 patients with acute promyelocytic leukemia (APL). Of 6 patients who had circulating leukemic blasts before treatment, 3 initially received ATRA alone but died of respiratory failure due to retinoic acid syndrome (RAS). High dose steroid therapy did not rescue RAS in these patients. Another 3 who were given intensive chemotherapy followed by ATRA and/or granulocyte colony-stimulating factor (G-CSF) achieved complete remission (CR). Of 3 patients without peripheral leukemic blasts before treatment, 1 received intensive chemotherapy followed by G-CSF and reached CR, 1 who had been previously given ATRA did not respond to ATRA, and 1 did not initially respond sufficiently to ATRA alone but responded dramatically to ATRA plus G-CSF. In the treatment of APL, appropriate combination of ATRA, G-CSF and chemotherapy should always be taken into consideration. In addition, RAS have to be carefully avoided when applying ATRA therapy in patients who have circulating leukemic blasts before treatment.     

Treatment results of intermittent and cyclic regimen with ATRA and chemotherapy in childhood acute promyelocytic leukemia. Children's Cancer and Leukemia Study Group

An intermittent and cyclic regimen with All-Trans Retinoic Acid (ATRA) and intensive chemotherapy was conducted due to pharmacokinetic studies on ATRA for acute promyelocytic leukemia (APL) in children. We have treated 17 children with APL using ATRA for remission induction followed by an intermittent schedule of ATRA plus intensive chemotherapy (APL-ATRA protocol). There were 10 males and 7 females. The median age was 9.0 years old. The median baseline white blood cell count was 12.1 x 10(3)/microliter, hemoglobin 7.8 g/dl, platelet 4.5 x 10(4) microliters at diagnosis. Sixteen patients showed t(15; 17) translocation. RT-PCR analysis was available in 15 patients and showed PML/RAR alpha rearrangement in all patients. Overall, 13 or 17 newly diagnosed patients (88%) achieved complete remission and EFS was 67%. Compared to the control (same chemotherapy without ATRA regimen), remission induction and EFS were significantly increased. The toxicity of ATRA consisted of retinoic acid syndrome in 1 and pseudotumor cerebli in another. Other toxicities included headache, chelitis, gastrointestinal trouble and bone pain. These results suggest that intermittent and cyclic regimen with ATRA and intensive chemotherapy (APL-ATRA protocol) is highly effective for APL patients.     

Cross-talk between retinoic acid and interferons: molecular mechanisms of interaction in acute promyelocytic leukemia cells

All-trans retinoic acid (ATRA) and interferons (IFNs) are active anticancer agents. ATRA is capable of inducing complete remission in acute promyelocytic leukemia (APL) patients, whereas IFNalpha is successfully used in the treatment of the stable phase of chronic myeloid leukemia. ATRA and IFNs have shown synergistic interactions in various experimental conditions and represent a potentially useful therapeutic combination in the treatment of various types of leukemias and solid tumors. The molecular basis of these interactions are poorly understood and need to be elucidated. In this review, we summarize a series of recent observations concerning the molecular mechanisms underlying the cross-talk between the intracellular pathways activated by ATRA and IFNs in APL cells. In APL blasts, IFNs regulate the expression of retinoic acid receptors, and ATRA, in turn, modulates the levels and the state of activation of members of the Jak-STAT second messenger pathway. This demonstrates a two-way interaction between ATRA and IFNs, which leads to cross-modulation of genes normally under the control of the retinoid and the cytokine. These data may be relevant in the context of a rational use of the combination between ATRA and IFNs in the clinical management of myeloid leukemias.     

Potentiated maturation with a high proliferating activity of acute promyelocytic leukemia induced in vitro by granulocyte or granulocyte/macrophage colony-stimulating factors in combination with all-trans retinoic acid

All-trans retinoic acid (ATRA) induces differentiation of acute promyelocytic leukemia (APL), but the effect of cytokines regulating myeloid differentiation on ATRA-induced APL cells is poorly understood. In this study, maturation and proliferation of fresh APL cells were examined when induced in vitro by granulocyte or granulocyte/macrophage colony-stimulating factors (G-CSF or GM-CSF) in combination with ATRA. APL cells showed a low proliferating activity when induced by ATRA alone. In contrast, cells induced by G-CSF or GM-CSF alone showed increased DNA syntheses, the levels of which were not significantly affected by the combination of ATRA with CSFs. Interestingly, G-CSF or GM-CSF potentiated the capability of ATRA-induced cells to reduce nitroblue tetrazolium (NBT), while G-CSF or GM-CSF alone induced no NBT reduction. Furthermore, in several patients examined, APL cells induced by ATRA with G-CSF showed an increased activity of chemotaxis and CD11a expression. These findings suggest that G-CSF or GM-CSF can potentiate differentiation of ATRA-induced APL cells while stimulating their proliferating activity as well, and that G-CSF, rather than GM-CSF, may be a useful adjunct to promote ATRA-induced differentiation of APL.     

Relapsed acute promyelocytic leukemia previously treated with all-trans retinoic acid: clinical experience with a new synthetic retinoid, Am-80

All-trans retinoic acid (ATRA), a potent differentiating drug for acute promyelocytic leukemia (APL), induces a high incidence of complete remission (CR) in patients with APL and is now established as a first-line therapy. However, ATRA resistance has become a clinical problem. Patients who relapsed after ATRA-induced CR have had difficulty in obtaining a second CR with ATRA therapy. Although several mechanisms have been postulated, treatment strategies to overcome resistance have not been established. We used a new synthetic retinoid, Am-80, as reinduction therapy for APL relapse after from ATRA-induced CR. Am-80 was several times more potent than ATRA in inducing differentiation in vitro. At a 6 mg/m2 dose, there were 24 evaluable patients; 14 (58%) achieved CR between days 20 and 58 (median, 37 days). Clinical response correlated with the in vitro response to Am-80. Adverse effects included retinoic acid syndrome (n = 1), hyperleukocytosis (n = 1), xerosis (n = 9), cheilitis (n = 8), hypertriglyceridemia (n = 16), and hypercholesterolemia (n = 15). Am-80 is active in APL after relapse from ATRA-induced CR. Further clinical trials are needed to establish strategies to overcome ATRA resistance.     

Differentiating therapy in acute myeloid leukemia

Differentiating therapy is a new antineoplastic strategy which has received increasing attention due to the remarkable activity of the vitamin A derivative, all-trans retinoic acid (ATRA) in patients with acute promyelocytic leukemia (APL). Although it has been known for years that a variety of agents, including retinoids, could induce leukemic cells to differentiate in vitro, it was not until the initial report from Shanghai in 1988 that laboratory studies translated into clinical activity and benefit in patients. Since this initial report, a number of studies have confirmed that the majority of patients with both newly diagnosed and previously chemotherapy-treated patients with APL achieve complete remission (CR) with ATRA. In addition, the characteristic life-threatening coagulopathy resolves quickly. Several limitations to this approach have emerged, including the development of retinoid resistance, hyperleukocytosis and the retinoic acid syndrome, a constellation of findings including unexplained fever, fluid retention, pleuropericardial effusions and pulmonary infiltrates. Although ATRA is very effective in inducing CR, its benefits compared to conventional chemotherapy are only now being addressed. The first prospective randomized trial comparing ATRA plus chemotherapy to chemotherapy alone was terminated early because of an improved event-free survival for patients receiving ATRA. The benefit was attributable to a difference in relapse rate. A large, intergroup, prospective, randomized trial comparing conventional chemotherapy to ATRA for induction and ATRA to observation for maintenance has recently completed accrual and will provide insight into the emerging role of ATRA in patients with APL. ATRA represents the first example of a specific form of antileukemic therapy targeting a specific genetic abnormality and may serve as a paradigm for the development of differentiating therapy for patients with other hematologic malignancies.     

Acute promyelocytic leukemia: all-trans retinoic acid (ATRA) along with chemotherapy is superior to ATRA alone

This study was conducted to compare the results of treatment of acute promyelocytic leukemia (APL) with all-trans retinoic acid alone (ATRA) or a combination therapy of ATRA followed by chemotherapy. Forty-three patients treated between February 1992 and February 1996 were included in this study. Eighteen patients were treated with ATRA alone and 25 patients were treated with ATRA followed by chemotherapy. The cytogenetic analysis was done in 41 patients at presentation, following treatment, and at follow-up. A complete response (CR) was achieved in 13 (72%) patients on ATRA and 19 (76%) on ATRA followed by chemotherapy. Eleven of 13 patients with response to ATRA alone relapsed with median survival of eight months (range, 1 to 28). One patient died of hepatitis in CR and one patient is alive 2 years after diagnosis. In the combination therapy arm, 10 patients are in CR with a median follow-up of 22 months (range, 6 to 56 months). After achieving a CR, four patients died due to infections during chemotherapy therapy, and only 5 of 19 patients have relapsed. Major cytogenetic response was seen in 8 of the 10 patients in whom cytogenetic data was available after treatment with ATRA at the time of remission. Similarly, 13 of 15 for whom data was available showed a major cytogenetic response after treatment with ATRA plus chemotherapy. Prior to relapse, 80% of the patients had an increase in the percentage of t(15;17) cells in the marrow. Patients with a complete hematological response but no cytogenetic response relapsed within six months. Ten patients died prior to response evaluation. Two patients who received ATRA died of retinoic acid syndrome, one of pneumonia, and one of intracranial hemorrhage. Of the six patients on ATRA and chemotherapy, four died of retinoic acid syndrome (RAS), one of intracranial hemorrhage, and one of left ventricular failure. Only one patient is alive at 24 months following treatment with ATRA alone. The relapse-free survival is 42% at four years for patients treated with ATRA followed by chemotherapy. This trial is a historical comparison of ATRA alone and ATRA with subsequent combination chemotherapy. Nonetheless, the trial shows a significant improvement in the event free survival of patients receiving chemotherapy as consolidation following ATRA.     

Trivalent antimonials induce degradation of the PML-RAR oncoprotein and reorganization of the promyelocytic leukemia nuclear bodies in acute promyelocytic leukemia NB4 cells

Acute promyelocytic leukemia (APL) is characterized by a specific t(15;17) chromosomal translocation that fuses the genes encoding the promyelocytic leukemia protein (PML) and the retinoic acid receptor (RAR). The resulting PML-RAR protein induces a block in the differentiation of the myeloid progenitor cells, which can be released by retinoic acid (RA) in vitro and in vivo. The RA-induced differentiation of APL blasts is paralleled by the degradation of the fusion protein and the relocation of wild-type PML from aberrant nuclear structures to its normal localization in nuclear bodies. Recently, arsenic trioxide (As2O3) treatment was proposed as an alternative therapy in APL, because it can induce complete remission in both RA-sensitive and -resistant APL patients. Intriguingly, As2O3 was also shown to induce degradation of the PML-RAR chimera and to reorganize PML nuclear bodies. Here we show that trivalent antimonials also have striking effects on RA-sensitive and RA-resistant APL cells. Treatment of the APL-derived NB4 cells and the RA-resistant subclone NB4R4 with antimony trioxide or potassium antimonyl tartrat triggers the degradation of the fusion protein and the concomitant reorganization of the PML nuclear bodies. In addition, as reported for As2O3, the antimonials provoke apoptosis of NB4 and NB4R4 cells. The mechanism of antimony action is likely to be similar to that of As2O3, notably both substances induce the attachment of the ubiquitin-like SUMO-1 molecule to the PML moiety of PML-RAR. From these data, we propose that, in analogy to As2O3, antimonials might have a beneficial therapeutic effect on APL patients, perhaps with less toxicity than arsenic.     

Effects of prostaglandin E2 and all-trans retinoic acid combination on induced differentiation of human acute promyelocytic leukemia NB4 cells

OBJECTIVE: A human promyelocytic leukemia (APL) cell line NB4 was used to demonstrate the synergistic effects between all-trans retinoic acid (ATRA) and prostaglandin E2 (PGE2) on growth inhibition and cytodifferentiation induction. METHODS: NB4 cells were cultured in the presence of either ATRA or PGE2 as a single agent or in combinations at various ratio. Cell growth was measured and myeloid differentiation was tested on consecutive days over the whole course of culture. RESULTS: PGE2 and ATRA synergistically induced the myeloid differentiation of NB4 cells. In comparison with ATRA alone, the combination of PGE2 with ATRA caused an almost 20-fold decrease of effective concentration of ATRA. CONCLUSION: The combination of ATRA and PGE2 at an appropriate ratio may provide a convenient oral regimen of combined differentiation therapy for a better clinical outcome in APL patients.     

A case of extrahepatic portal vein aneurysm with massive thrombosis: diagnosis with reconstruction images from helical CT scans

Acute promyelocytic leukemia (APL) originate from chromosomal translocations generating two types of fusion proteins both involving the retinoic acid receptor alpha (RAR alpha) and either the gene PML (t(15;17)) or PLZF (t(11;17)). Recent publications cast a new light on the detailed molecular mechanism underlying the oncogenic activity of these fusion proteins which block myeloid terminal differentiation by recruiting histone deacetylases to the promoters of target genes through co-repressor proteins. They also explain the different responses to treatment by all-trans retinoic acid (ATRA) of these two variants which are otherwise clinically indistinguishable.     

Effect of acute acipimox administration on the rates of lipid and glycogen synthesis in cachectic tumor-bearing rats

2'-Deoxycoformycin (dCF), a specific and potent inhibitor of adenosine deaminase, has demonstrated significant antitumor effect on lymphoid malignancies. The drug induced functional and morphologic differentiation of myeloid leukemia cells in combination with 2'-deoxyadenosine (dAd), but not dCF alone. NB4, a cell line derived from a patient with t(15; 17) acute promyelocytic leukemia (APL) underwent granulocytic differentiation when treated with all-trans retinoic acid (ATRA) or dCF plus dAd, but not with cytosine arabinoside. Pre-exposure of NB4 cells to ATRA greatly potentiated differentiation induced by dCF plus dAd, but pretreatment with dCF plus dAd before exposure to ATRA was less effective. Differentiation of NB4 cells was effectively induced by clinically applicable concentrations of dCF in combination with dAd. These findings may provide useful information about induction of differentiation in vivo.     

三氧化二砷联合全反式维甲酸治疗初发急性早幼粒细胞白血病50例疗效观察

目的 观察三氧化二砷(ATO)联合全反式维甲酸(ATRA)治疗初发急性早幼粒细胞白血病(APL)的疗效.方法 98例初发APL患者分为对照组和治疗组,对照组48例,治疗组50例.对照组采用常规ATRA+DA双诱导方案治疗;治疗组采用ATRA每天25 mg/m2,ATO每天0.15 mg/kg(ATRA后第10天开始)联合治疗,直至完全缓解(CR),CR后接受ATO和ATRA联合巩固治疗.比较两组CR率、PML-RAR α融合基因转阴时间及5年无病生存率.结果 对照组和治疗组CR率分别为89.5%(43/48)和90.0%(45/50),获得CR时间分别为(30.0±5.1)d和(28.1±4.4)d,两组CR率(x2=-0.068,P=0.946)及获得CR时间(t=1.757,P=0.083)相比差异均无统计学意义.在所有获得CR的患者中,3例分别在CR后第276、385和394天复发.所有患者发病时PML-RAR α融合基因均阳性,对照组和治疗组CR时分别有25.0%(5/20)和29.4%(5/17)转阴,巩固后分别有92.5%(37/40)和97.6%(41/42)转阴.对照组和治疗组5年无病生存率分别为(85.3±5.9)%和(87.6±5.6)%,差异无统计学意义(x2=0.232,P=0.630).结论 ATO联合ATRA能有效治疗初发APL患者,可以作为常规化疗方案外的另一选择.     

Infrequent alterations of the RAR alpha gene in acute myelogenous leukemias, retinoic acid-resistant acute promyelocytic leukemias, myelodysplastic syndromes, and cell lines

Retinoids are important regulators of cell growth and differentiation in vitro and in vivo and they exert their biologic activities by binding to nuclear retinoic acid receptors (RARs; alpha, beta, and gamma) and retinoid X receptors (RXRs; alpha, beta, and gamma). All-trans retinoic acid (RA) induces complete remission in patients with acute promyelocytic leukemia (APL) presumably by binding directly to RAR alpha of APL cells. Leukemic blasts from APL patients initially responsive to RA can become resistant to the agent. HL-60 myeloblasts cultured with RA have developed mutations of the ligand-binding region of RAR alpha and have become resistant to RA. Furthermore, insertion of an RAR alpha with an alteration in the ligand-binding region into normal murine bone marrow cells can result in growth factor-dependent immortalization of the early hematopoietic cells. To determine if alterations of the ligand binding domain of RAR alpha might be involved in several malignant hematologic disorders, the mutational status of this region (exons 7, 8, and 9) was examined in 118 samples that included a variety of cell lines and fresh cells from patients with myelodysplastic syndromes (MDS) and acute myeloid leukemias (AML), including 20 APL patients, 5 of whom were resistant to RA and 1 who was refractory to RA at diagnosis, using polymerase chain reaction-single-strand conformational polymorphism (PCR-SSCP) analysis and DNA sequencing. In addition, 7 of the 20 APLs were studied for alterations of the other coding exons of the gene (exons 2 through 6). No mutations of RAR alpha were detected. Although the sensitivity of PCR-SSCP analysis is less than 100%, these findings suggest that alterations of RAR alpha gene are rare and therefore other mechanisms must be involved in the onset of resistance to retinoids and in the lack of differentiation in disorders of the myeloid lineage.     

A numerical investigation into factors affecting anesthetic distribution during spinal anesthesia

Differentiation therapy for acute promyelocytic leukemia (APL) using all-trans-retinoic acid (ATRA) has improved the prognosis of the disease. ATRA therapy also causes a newly recognized clinical syndrome, the "retinoic acid syndrome" (RAS), which can be successfully managed with dexamethasone. Because aberrant function of maturing leukemic granulocytes may cause this syndrome, and because dexamethasone is useful clinically, we studied functional properties of maturing HL60 cells cultured in the presence and absence of dexamethasone. HL60 cells were cultured for 4 days with ATRA and studied daily to determine acquisition of mature neutrophil-like properties including phagocytosis, NBT reduction, actin polymerization, chemotaxis and adhesion molecule expression. Undifferentiated HL60 cells could not polymerize actin or reduce NBT, and exhibited only a minimal ability to undergo chemotaxis or ingest latex beads. Following 4 days of maturation with ATRA, the cells would increase F-actin content in response to interleukin-8, ingest latex beads, migrate in a chemotaxis chamber, reduce NBT, and express CD11b. When dexamethasone was added to the cells in culture, there was no major enhancement or suppression of these properties. We also studied the effect of dexamethasone on functional properties of normal neutrophils and found minimal if any effect on their function. Overall, these studies suggest that in vitro, dexamethasone has little effect on the function of leukemic and normal granulocytes. To further investigate the pathophysiology of the retinoic acid syndrome, future studies may need to use endothelial cells, cytokines, or granulocytes obtained from APL patients.