Effective treatment of acute promyelocytic leukemia with all-trans-retinoic acid, arsenic trioxide, and gemtuzumab ozogamicin

Anti-estrogen resistance in breast cancer is induced by the tumor microenvironment and can be overcome by inhibiting mitochondrial function in epithelial cancer cells

Here, we show that tamoxifen resistance is induced by cancer-associated fibroblasts (CAFs). Coculture of estrogen receptor positive (ER+) MCF7 cells with fibroblasts induces tamoxifen and fulvestrant resistance with 4.4 and 2.5-fold reductions, respectively, in apoptosis compared with homotypic MCF7 cell cultures. Treatment of MCF7 cells cultured alone with high-energy mitochondrial "fuels" (L-lactate or ketone bodies) is sufficient to confer tamoxifen resistance, mimicking the effects of coculture with fibroblasts. To further demonstrate that epithelial cancer cell mitochondrial activity is the origin of tamoxifen resistance, we employed complementary pharmacological and genetic approaches. First, we studied the effects of two mitochondrial "poisons," namely metformin and arsenic trioxide (ATO), on fibroblast-induced tamoxifen resistance. We show here that treatment with metformin or ATO overcomes fibroblast-induced tamoxifen resistance in MCF7 cells. Treatment with the combination of tamoxifen plus metformin or ATO leads to increases in glucose uptake in MCF7 cells, reflecting metabolic uncoupling between epithelial cancer cells and fibroblasts. In coculture, tamoxifen induces the upregulation of TIGAR (TP53-induced glycolysis and apoptosis regulator), a p53 regulated gene that simultaneously inhibits glycolysis, autophagy and apoptosis and reduces ROS generation, thereby promoting oxidative mitochondrial metabolism. To genetically mimic the effects of coculture, we next recombinantly overexpressed TIGAR in MCF7 cells. Remarkably, TIGAR overexpression protects epithelial cancer cells from tamoxifen-induced apoptosis, providing genetic evidence that increased mitochondrial function confers tamoxifen resistance. Finally, CAFs also protect MCF7 cells against apoptosis induced by other anticancer agents, such as the topoisomerase inhibitor doxorubicin (adriamycin) and the PARP-1 inhibitor ABT-888. These results suggest that the tumor microenvironment may be a general mechanism for conferring drug resistance. In summary, we have discovered that mitochondrial activity in epithelial cancer cells drives tamoxifen resistance in breast cancer and that mitochondrial "poisons" are able to re-sensitize these cancer cells to tamoxifen. In this context, TIGAR may be a key "druggable" target for preventing drug resistance in cancer cells, as it protects cancer cells against the onset of stress-induced mitochondrial dys-function and aerobic glycolysis.

Advances in therapies for acute promyelocytic leukemia

Acute promyelocytic leukemia (APL), a distinct subtype of acute myelogenous leukemia (AML), results from the arrest of the maturation of hematopoietic progenitors at the promyelocyte stage. It has been shown that APL is associated with a reciprocal chromosomal translocation, involving chromosomes 15 and 17, which fuses the gene encoding the retinoic acid receptor α (RARα) and the promyelocytic leukemia (PML) gene. The resultant PML-RARα fusion protein plays a critical role in the pathogenesis of APL. Although there are many subtypes of AML, all are typically managed using a standard chemotherapy regimen of an anthracycline plus cytarabine arabinoside (CA). Despite high rates of complete remission following standard chemotherapy, most patients relapse and long-term disease-free survival is only 30-40%. The introduction of drugs such as all-trans retinoic acid (ATRA) that promote progenitor differentiation by directly inhibiting the PML-RARα fusion protein has changed the treatment paradigm for APL and markedly improved patient survival. The purposes of the present review are to provide the latest results and future directions of clinical research into APL and to illustrate how new therapies, such as ATRA plus anthracycline-based induction and consolidation therapy, risk-adapted therapy, salvage therapy containing arsenic trioxide-based regimens, and hematopoietic stem cell transplantation, have improved the treatment outcomes for APL patients.

Differentiation syndrome in promyelocytic leukemia: clinical presentation, pathogenesis and treatment

Differentiation syndrome (DS) represents a life-threatening complication in patients with acute promyelocytic leukemia (APL) undergoing induction therapy with all-trans retinoic acid (ATRA) or arsenic trioxide (ATO). It affected about 20–25% of all patients and so far there are no definitive diagnostic criteria. Clinically, DS is characterized by weight gain, fever not attributable to infection, respiratory distress, cardiac involvement, hypotension, and/or acute renal failure. At the histological point of view, there is an extensive interstitial and intra-alveolar pulmonary infiltration by maturing myeloid cells, endothelial cell damage, intra-alveolar edema, inter-alveolar hemorrhage, and fibrinous exsudates. DS pathogenesis is not completely understood, but it is believed that an excessive inflammatory response is the main phenomenon involved, which results in increased production of chemokines and expression of adhesion molecules on APL cells. Due to the high morbidity and mortality associated with DS, its recognition and the prompt initiation of the treatment is of utmost importance. Dexamethasone is considered the mainstay of treatment of DS, and the recommended dose is 10 mg twice daily by intravenous route until resolution of DS. In severe cases (respiratory or acute renal failure) it is recommended the discontinuation of ATRA or ATO until recovery.

The retinoid signalling molecule, TRIM16, is repressed during squamous cell carcinoma skin carcinogenesis in vivo and reduces skin cancer cell migration in vitro

Retinoid therapy is used for chemo-prevention in immuno-suppressed patients at high risk of developing skin cancer. The retinoid signalling molecule, tripartite motif protein 16 (TRIM16), is a regulator of keratinocyte differentiation and a tumour suppressor in retinoid-sensitive neuroblastoma. We sought to determine the role of TRIM16 in skin squamous cell carcinoma (SCC) pathogenesis. We have shown that TRIM16 expression was markedly reduced during the histological progression from normal skin to actinic keratosis and SCC. SCC cell lines exhibited lower cytoplasmic and nuclear TRIM16 expression compared with primary human keratinocyte (PHK) cells due to reduced TRIM16 protein stability. Overexpressed TRIM16 translocated to the nucleus, inducing growth arrest and cell differentiation. In SCC cells, TRIM16 bound to and down regulated nuclear E2F1, this is required for cell replication. Retinoid treatment increased nuclear TRIM16 expression in retinoid-sensitive PHK cells, but not in retinoid-resistant SCC cells. Overexpression of TRIM16 reduced SCC cell migration, which required the C-terminal RET finger protein (RFP)-like domain of TRIM16. The mesenchymal intermediate filament protein, vimentin, was directly bound and down-regulated by TRIM16 and was required for TRIM16-reduced cell migration. Taken together, our data suggest that loss of TRIM16 expression plays an important role in the development of cutaneous SCC and is a determinant of retinoid sensitivity.

Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Impact of arsenic trioxide in the treatment of acute promyelocytic leukemia

Arsenic trioxide (ATO) is presently the most active single agent in the treatment of acute promyelocytic leukemia (APL). This review provides insights into the mode of action and the pharmacological properties of ATO, and summarizes the most relevant results of more than 20 treatment studies in relapsed or newly diagnosed APL published between 1997 and 2011. ATO acts by targeting multiple pathways in APL leading to apoptosis and myeloid differentiation. It induces complete remission without myelosuppression and causes only few adverse effects. In relapsed APL, ATO-based salvage therapy has been able to induce long-lasting remissions and possible cure in 50-81% of patients. In newly diagnosed APL, two main strategies are currently pursued. ATO is either included into induction therapy with the aim to minimize or eliminate chemotherapy, or it is incorporated as an additive into established first-line concepts with all-trans-retinoic acid and chemotherapy to reinforce their anti-leukemic efficacy. Recent results suggest a high efficacy of ATO in both concepts. In conclusion, experimental research and clinical studies have made contributions toward a better understanding of the molecular mechanisms induced by ATO in APL cells and have established this historic substance as an important candidate for the further improvement of APL therapy.

Treatment of acute promyelocytic leukemia with high white cell blood counts

Acute promyelocytic leukemia (APL) with WBC above 10 G/L has long been considered, even in the all-trans retinoic acid (ATRA) era, to carry a relatively poor prognosis (compared to APL with WBC below 10 G/L), due to increased early mortality and relapse. However, early deaths can to a large extent be avoided if specific measures are rapidly instigated, including prompt referral to a specialized center, immediate onset of ATRA and chemotherapy, treatment of coagulopathy with adequate platelet transfusional support, and prevention and management of differentiation syndrome. Strategies to reduce relapse rate include chemotherapy reinforcement with cytarabine and/or arsenic trioxide during consolidation, prolonged maintenance treatment, especially with ATRA and low dose chemotherapy, and possibly, although this is debated, intrathecal prophylaxis to prevent central nervous system relapse. By applying those measures, outcomes of patients with high risk APL have considerably improved, and have become in many studies almost similar to those of standard risk APL patients.

(+)α-Tocopheryl succinate inhibits the mitochondrial respiratory chain complex I and is as effective as arsenic trioxide or ATRA against acute promyelocytic leukemia in vivo

The vitamin E derivative (+)α-tocopheryl succinate (α-TOS) exerts pro-apoptotic effects in a wide range of tumors and is well tolerated by normal tissues. Previous studies point to a mitochondrial involvement in the action mechanism; however, the early steps have not been fully elucidated. In a model of acute promyelocytic leukemia (APL) derived from hCG-PML-RARα transgenic mice, we demonstrated that α-TOS is as effective as arsenic trioxide or all-trans retinoic acid, the current gold standards of therapy. We also demonstrated that α-TOS induces an early dissipation of the mitochondrial membrane potential in APL cells and studies with isolated mitochondria revealed that this action may result from the inhibition of mitochondrial respiratory chain complex I. Moreover, α-TOS promoted accumulation of reactive oxygen species hours before mitochondrial cytochrome c release and caspases activation. Therefore, an in vivo antileukemic action and a novel mitochondrial target were revealed for α-TOS, as well as mitochondrial respiratory complex I was highlighted as potential target for anticancer therapy.

Phase II Study of Single-Agent Arsenic Trioxide for the Front-Line Therapy of Acute Promyelocytic Leukemia

Purpose

The long-term follow-up results of patients with acute promyelocytic leukemia (APL) treated with all-trans retinoic acid and chemotherapy show high cure rates. Several studies have shown high efficacy of single-agent arsenic trioxide in newly diagnosed APL. However, long-term follow-up results are needed.

Patients and Methods

One hundred ninety-seven patients with newly diagnosed APL were treated with arsenic trioxide 0.15 mg/kg daily intravenous infusion until complete remission (CR). After achieving CR, the patients received one to four more courses of therapy with arsenic trioxide as consolidation and were observed with reverse-transcriptase polymerase chain reaction studies from peripheral blood (to detect of minimal residual disease) every 3 months or until relapse or death.

Results

The morphologic CR rate was 85.8%. The most common cause of remission failure was early death owing to APL differentiation syndrome (13.2%). The most important prognostic factor for early mortality was a high WBC count at presentation. The 5-year disease-free survival (DFS) rate was 66.7% ± 4% (SE). Relapse after 5 years in CR was rare. The 5-year overall survival (OS) rate by intention-to-treat analysis was 64.4% ± 4%. In patients who achieved CR, OS and DFS were identical.

Conclusion

The long-term follow-up of newly diagnosed patients with APL treated with single-agent arsenic trioxide shows high rates of DFS and OS.

Arsenic and its combinations in cancer therapeutics

Arsenic is a metalloid that is considered to be a paradox in terms of its role both as a carcinogen and as a therapeutic agent. Chronic exposure to arsenic in drinking water has been linked with the development of various pathological conditions including cancer. Nevertheless, the therapeutic potential of arsenic and its derivatives in a variety of diseases have been exploited in the past. However, its role and mechanism of action as a therapeutic agent still remain an active area of research and investigation. Our ongoing work also suggests varied responses in cancer cells exposed to lower versus higher concentrations of arsenic. Furthermore, the arsenic combinations with chemopreventive or anticancer agents have been observed to sensitize the cell for cell-cycle arrest and cell death. Here, we have provided the account of recent updates on the mechanism of action of arsenic and its derivatives that lead to various disorders, and its role as a therapeutic agent both as a single agent as well as in combination chemotherapy.

Phase II Trial of Cisplatin, Gemcitabine, and Bevacizumab As First-Line Therapy for Metastatic Urothelial Carcinoma: Hoosier Oncology Group GU 04-75

Purpose

Novel approaches are needed for patients with metastatic urothelial cancer (UC). This trial assessed the efficacy and toxicity of bevacizumab in combination with cisplatin and gemcitabine (CGB) as first-line treatment for patients with metastatic UC.

Patients and Methods

Chemotherapy-naive patients with metastatic or unresectable UC received cisplatin 70 mg/m2on day 1, gemcitabine 1,000 to 1,250 mg/m2on days 1 and 8, and bevacizumab 15 mg/kg on day 1, every 21 days.

Results

Forty-three patients with performance status of 0 (n = 26) or 1 (n = 17) and median age of 66 years were evaluable for toxicity and response. Grade 3 to 4 hematologic toxicity included neutropenia (35%), thrombocytopenia (12%), anemia (12%), and neutropenic fever (2%). Grade 3 to 5 nonhematologic toxicity included deep vein thrombosis/pulmonary embolism (21%), hemorrhage (7%), cardiac (7%), hypertension (5%), and proteinuria (2%). Three treatment-related deaths (CNS hemorrhage, sudden cardiac death, and aortic dissection) were observed. Best response by Response Evaluation Criteria in Solid Tumors was complete response in eight patients (19%) and partial response in 23 patients (53%), for an overall response rate of 72%. Stable disease lasting ≥ 12 weeks occurred in four patients (9%), and progressive disease occurred in six patients (14%). With a median follow-up of 27.2 months (range, 3.5 to 40.9 months), median progression-free survival (PFS) was 8.2 months (95% CI, 6.8 to 10.3 months) with a median overall survival (OS) time of 19.1 months (95% CI, 12.4 to 22.7 months). The study-defined goal of 50% improvement in PFS was not met.

Conclusion

CGB demonstrates promising OS and antiangiogenic treatment-related toxicities in the phase II setting of metastatic UC. The full risk/benefit profile of CGB in patients with metastatic UC will be determined by an ongoing phase III intergroup trial.

Natural history of paclitaxel-associated acute pain syndrome: prospective cohort study NCCTG N08C1

PURPOSE

The characteristics and natural history of the paclitaxel-acute pain syndrome (P-APS) and paclitaxel's more chronic neuropathy have not been well delineated.

METHODS

Patients receiving weekly paclitaxel (70 to 90 mg/m(2)) completed daily questionnaires and weekly European Organisation for Research and Treatment of Cancer (EORTC) Chemotherapy-Induced Peripheral Neuropathy (CIPN) -20 instruments during the entire course of therapy.

RESULTS

P-APS symptoms peaked 3 days after chemotherapy. Twenty percent of patients had pain scores of 5 to 10 of 10 with the first dose of paclitaxel. Sensory neuropathy symptoms were more prominent than were motor or autonomic neuropathy symptoms. Of the sensory neuropathy symptoms, numbness and tingling were more prominent than was shooting or burning pain. Patients with higher P-APS pain scores with the first dose of paclitaxel appeared to have more chronic neuropathy.

CONCLUSION

These data support that the P-APS is related to nerve pathology as opposed to being arthralgias and/or myalgias. Numbness and tingling are more prominent chronic neuropathic symptoms than is shooting or burning pain.

New considerations in the design of clinical trials for the treatment of acute leukemia

There is great need for improved therapy for patients with acute leukemia. The current systems of clinical drug development and delivery of leukemia care are imperfectly adapted to the optimal identification and testing of future regimens. Novel clinical trial design with increased enrolment and appropriate end point selection would facilitate more efficient validation of candidate therapies. Clinical outcomes registries and biological sample storage would allow patient and leukemic factor substratification for the development of the next generation of targeted personalized therapy. We believe that the standard of care for patients in the USA diagnosed with acute leukemia, if treated with curative intent, is referral to a specialized center where an appropriate clinical trial can be offered.

Treatment of acute promyelocytic leukemia for older patients

Acute promyelocytic leukemia (APL) represents a remarkable disease in which leukemogenesis is driven by the PML-RARα oncogene and for which targeted treatment with all-trans retinoic acid (ATRA)-based therapy allows substantial chance of cure. APL is seen in a small subset of older patients, with age representing one of the most important prognostic factors for outcome of treatment. Unlike other acute leukemias, the inferior outcomes for APL in older patients relates less to changes in disease biology and more to the increased toxicity of ATRA and the chemotherapy combination regimens used to induce hematologic and molecular responses. Risk-adapted strategies that use less-toxic agents, such as arsenic trioxide, allow treatment of older patients, with greater efficiency and better chances of cure.

Modern Approaches to Treating Acute Promyelocytic Leukemia

The advent of all-trans-retinoic acid (ATRA) and its combination with anthracycline-containing chemotherapy have contributed in the past 2 decades to optimize the antileukemic efficacy in acute promyelocytic leukemia (APL), leading to complete remission rates greater than 90%, virtual absence of resistance, and cure rates of nearly 80%. Recently reported studies from large cooperative trials have also shown that more rational delivery of treatment and improved outcomes may derive from the use of risk-adapted protocols. In particular, patients at higher risk of relapse (ie, those presenting with WBC > 10 × 109/L) seem to benefit from treatments that include cytarabine in the ATRA-plus-chemotherapy scheme, whereas patients with standard-risk disease can be successfully managed with less-intensive regimens that contain ATRA and anthracycline-based chemotherapy. After the outstanding results with arsenic trioxide (ATO) in the treatment of APL relapse, several experimental trials have been designed to explore the role of ATO in front-line therapy with the aim not only of minimizing the use of chemotherapy but also to reinforce standard ATRA-plus-chemotherapy regimens and additionally improve therapeutic efficacy. In this review article, we discuss most recent advances in the treatment of patients with newly diagnosed and relapsed APL.

Congestive heart failure risk in patients with breast cancer treated with bevacizumab

PURPOSE

Bevacizumab is a treatment option in patients with metastatic breast cancer. Congestive heart failure (CHF) has been reported, although the overall incidence and relative risk (RR) of this complication remains unclear. We performed an up-to-date, comprehensive meta-analysis to determine the risk of serious CHF in patients with breast cancer receiving bevacizumab.

METHODS

The databases of Medline were searched for articles from 1966 to March 2010. Abstracts presented at the American Society of Clinical Oncology and the San Antonio Breast Cancer Symposium meetings were also searched for relevant clinical trials. Eligible studies include randomized trials with bevacizumab in patients with breast cancer. Adequate reporting of safety profile data was required for inclusion. Statistical analyses were conducted to calculate the summary incidence, RR, and 95% CIs by using random-effects models.

RESULTS

A total of 3,784 patients were included. Overall incidence results for high-grade CHF in bevacizumab- and placebo-treated patients were 1.6% (95% CI, 1.0% to 2.6%) and 0.4% (95% CI, 0.2% to 1.0%), respectively. The RR of CHF in bevacizumab-treated patients was 4.74 (95% CI, 1.66 to 11.18; P = .001) compared with placebo-treated ones. In subgroup analyses, there were no significant differences in CHF incidence or risk between patients treated with low-dose (2.5 mg/kg) versus high-dose (5 mg/kg) bevacizumab or among patients treated with different chemotherapy regimens. No evidence of publication bias was observed.

CONCLUSION

This is the first comprehensive report to show that bevacizumab is associated with an increased risk of significant heart failure in patients with breast cancer.

Gemtuzumab ozogamicin for the treatment of acute promyelocytic leukemia: mechanisms of action and resistance, safety and efficacy

INTRODUCTION

Acute promyelocytic leukemia (APL) is characterized by peculiar biological features and high sensitivity to therapeutic agents such as anthracyclines, all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). Because cure rates of up to 80 - 90% have been reported using various combinations of the above agents, future strategies will probably aim at reducing therapy-related toxicity while maintaining therapeutic efficacy. Gemtuzumab ozogamicin (GO) is a calicheamicin-conjugated mAb directed against CD33, a surface antigen highly expressed on APL blasts. GO has been shown to be effective in this disease and better tolerated than conventional chemotherapy.

AREAS COVERED

This review looks at the mechanism of action, pathways associated with resistance and toxicity profile of GO. Reported experience on the use of GO for relapsed or newly diagnosed APL is also discussed along with evidence on its efficacy and relative tolerability in APL management. In addition to its activity in advanced disease, data suggest that GO in various combinations may replace chemotherapy in APL front-line therapy. This should apply in particular to some subsets such as elderly patients or those unfit to receive conventional chemotherapy.

EXPERT OPINION

GO has proven effective and relatively safe as a single agent in advanced APL. In combinations with ATRA and/or ATO, GO may substitute for conventional chemotherapy of APL, particularly in unfit patients.

Advances in understanding the pulmonary infiltration in acute promyelocytic leukaemia

In acute promyelocytic leukaemia (APL), differentiation therapy can be complicated by the development of a differentiation syndrome (DS). Pulmonary infiltration of differentiating leukaemic cells is a key event in the development of DS. Several mediators have been identified that may promote migration and extravasation of differentiating APL cells from the bloodstream into the tissue. Adhesion of APL cells to each other and to the endothelium is induced by upregulation of the expression of adhesion molecules and constitutively active β2-integrins during differentiation therapy. The expression of chemokines and their receptors is significantly upregulated as well. Pulmonary chemokine production can trigger transendothelial migration of differentiating APL cells from the bloodstream into the underlying tissue (initiation phase of DS). Massive production of chemokines by infiltrated APL cells can further enhance transendothelial migration of differentiating APL cells, causing an uncontrollable hyperinflammatory reaction in the lung (aggravation phase), which is not efficiently switched-off by corticosteroids.

Acute promyelocytic leukaemia: novel insights into the mechanisms of cure

The fusion oncogene, promyelocytic leukaemia (PML)-retinoic acid receptor-α (RARA), initiates acute promyelocytic leukaemia (APL) through both a block to differentiation and increased self-renewal of leukaemic progenitor cells. The current standard of care is retinoic acid (RA) and chemotherapy, but arsenic trioxide also cures many patients with APL, and an RA plus arsenic trioxide combination cures most patients. This Review discusses the recent evidence that reveals surprising new insights into how RA and arsenic trioxide cure this leukaemia, by targeting PML-RARα for degradation. Drug-triggered oncoprotein degradation may be a strategy that is applicable to many cancers.

Classification and risk stratification for acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) as a distinct clinical entity was first described only 50 years ago. The last twenty years are notable for rapid advances in understanding the molecular basis of the disease as well as dramatic improvements in treating APL. A new classification system that stratifies patients by risk has also lead to dramatic improvement in managing the disease. Molecular monitoring for minimal residual disease holds great promise for continued improvement in decreasing relapse risk. We are now able to tailor our therapy based on risk of relapse, and ongoing clinical trials use this risk-adapted framework in an attempt to further improve outcomes.

Treatment of patients with acute promyelocytic leukemia: a consensus statement on risk-adapted approaches to therapy

The integration of all-trans-retinoic acid (ATRA) with anthracycline chemotherapy into up-front regimens for acute promyelocytic leukemia (APL) has produced striking improvements in clinical outcomes, making APL one of the most curable forms of hematologic malignancies in adults. In addition, arsenic trioxide has proven efficacy in relapse and when combined with ATRA in frontline regimens has demonstrated high efficacy in a number of trials and the potential to replace chemotherapy, which would thereby reduce chemotherapy-related adverse events. Cure in APL is also largely dependent on timely and effective supportive care measures that counteract such life-threatening emergencies as coagulopathy and APL differentiation syndrome. The risk of mortality during induction and the risk of relapse following frontline therapy are related to the individual's initial clinical presentation and relapse-risk score at diagnosis; however, these risks are now quite low even in high-risk patients as long as appropriate therapy is initiated expeditiously. Multiple European and North American trials have investigated risk-adapted approaches to the treatment of APL and have reported high success rates. Further refinement of risk-adapted strategies is ongoing and will likely contribute to better patient care. A roundtable conference was conducted to discuss risk-adapted therapy for APL and to develop a consensus statement and approach for clinical oncologists. Expert opinions and evidence-based strategies presented during the roundtable are summarized herein.

Outcome of therapy-related acute promyelocytic leukemia with or without arsenic trioxide as a component of frontline therapy

BACKGROUND

Patients with therapy-related acute promyelocytic leukemia (t-APL) have been commonly exposed to topoisomerase inhibitors and may potentially benefit from induction regimens omitting anthracyclines.

METHODS

Retrospective analysis of the outcomes of 29 patients with t-APL who were either treated with arsenic trioxide (ATO) and all-trans-retinoic acid (ATRA) or with standard ATRA plus anthracycline-based chemotherapy was performed.

RESULTS

Prior therapy included chemotherapy alone, radiation alone, or a combination of the 2 in 19%, 33%, and 47% of patients, respectively. The combination of ATO and ATRA (n = 19) for induction resulted in a similar remission rate compared with ATRA plus chemotherapy (n = 10) (89% vs 70%; P = .35). The median overall survival for the patients treated with ATRA plus ATO was not reached compared with that for patients treated with ATRA plus chemotherapy (161 weeks; P = .79).

CONCLUSIONS

In this cohort of t-APL patients, outcomes with ATO and ATRA appeared to be comparable to anthracycline-containing induction regimens. This combination may be preferable in t-APL patients to avoid any risk of anthracycline-induced toxicities.

Arsenic trioxide improves event-free and overall survival for adults with acute promyelocytic leukemia: North American Leukemia Intergroup Study C9710

Arsenic trioxide (As(2)O(3)) is a highly effective treatment for patients with relapsed acute promyelocytic leukemia (APL); its role as consolidation treatment for patients in first remission has not been defined. We randomized 481 patients (age ≥ 15 years) with untreated APL to either a standard induction regimen of tretinoin, cytarabine, and daunorubicin, followed by 2 courses of consolidation therapy with tretinoin plus daunorubicin, or to the same induction and consolidation regimen plus two 25-day courses of As(2)O(3) consolidation immediately after induction. After consolidation, patients were randomly assigned to one year of maintenance therapy with either tretinoin alone or in combination with methotrexate and mercaptopurine. Ninety percent of patients on each arm achieved remission and were eligible to receive their assigned consolidation therapy. Event-free survival, the primary end point, was significantly better for patients assigned to receive As(2)O(3) consolidation, 80% compared with 63% at 3 years (stratified log-rank test, P < .0001). Survival, a secondary end point, was better in the As(2)O(3) arm, 86% compared with 81% at 3 years (P = .059). Disease-free survival, a secondary end point, was significantly better in the As(2)O(3) arm, 90% compared with 70% at 3 years (P < .0001). The addition of As(2)O(3) consolidation to standard induction and consolidation therapy significantly improves event-free and disease-free survival in adults with newly diagnosed APL. This trial was registered at clinicaltrials.gov (NCT00003934).

Front-line treatment of acute promyelocytic leukemia with AIDA induction followed by risk-adapted consolidation for adults younger than 61 years: results of the AIDA-2000 trial of the GIMEMA Group

After the identification of discrete relapse-risk categories in patients with acute promyelocytic leukemia (APL) receiving all-trans retinoic and idarubicin (AIDA)-like therapies, the Gruppo Italiano Malattie Ematologiche dell'Adulto (GIMEMA) designed a protocol for newly diagnosed APL (AIDA-2000) in which postremission treatment was risk-adapted. Patients with low/intermediate risk received remission at 3 anthracycline-based consolidation courses, whereas high-risk patients received the same schedule as in the previous, non-risk-adapted AIDA-0493 trial including cytarabine. In addition, all patients in the AIDA-2000 received all-trans retinoic acid (ATRA) for 15 days during each consolidation. After induction, 600 of 636 (94.3%) and 420 of 445 (94.4%) patients achieved complete remission in the AIDA-0493 and AIDA-2000, respectively. The 6-year overall survival and cumulative incidence of relapse (CIR) rates were 78.1% versus 87.4% (P = .001) and 27.7% versus 10.7% (P < .0001). Significantly lower CIR rates for patients in the AIDA-2000 were most evident in the high-risk group (49.7% vs 9.3%, respectively, P < .0001). Our data confirm that anthracycline-based consolidation is at least equally effective as cytarabine-containing regimens for low-/intermediate-risk patients and suggest that a risk-adapted strategy including ATRA for consolidation improves outcome in newly diagnosed APL. Furthermore, our results highlight the role of cytarabine coupled to anthracyclines and ATRA during consolidation in the high-risk group.

Single-agent arsenic trioxide in the treatment of newly diagnosed acute promyelocytic leukemia: long-term follow-up data

PURPOSE We previously reported our results with a single-agent arsenic trioxide (ATO) -based regimen in newly diagnosed cases of acute promyelocytic leukemia (APL). The concern remained about the long-term outcome of this well-tolerated regimen. We report our long-term follow-up data on the same cohort. PATIENTS AND METHODS From January 1998 to December 2004, 72 patients with PML/RARalpha+ APL were enrolled. All patients were treated with a single-agent ATO regimen. Results Overall 62 (86.1%) achieved a hematologic remission (complete remission). After the initial report, an additional seven patients have relapsed for a total of 13 relapses. There were no additional toxicities to report on follow-up. At a median follow-up 60 months, the 5-year Kaplan-Meier estimate (+/- SE) of event-free survival, disease-free survival, and overall survival (OS) was 69% +/- 5.5%, 80% +/- 5.2%, and 74.2% +/- 5.2%, respectively. The OS in the good risk group as defined by us remains 100% over this period. CONCLUSION Single-agent ATO as used in this study in the management of newly diagnosed cases of APL is safe and is associated with durable responses. Results in the low-risk group are comparable to that reported with conventional therapy while additional interventions would probably be required in high-risk cases.

Arsenic trioxide - An old drug rediscovered

Over the last 17 years, clinical trials conducted worldwide have demonstrated the efficacy of arsenic trioxide (As(2)O(3)) in the treatment of relapsed acute promyelocytic leukemia (APL). Currently, the role of As(2)O(3) in front-line therapy is under investigation. Recent trials in the US have demonstrated that the addition of As(2)O(3) to standard treatment regimens improves survival outcomes in patients with APL and may allow a reduction in cytotoxic chemotherapy exposure. As(2)O(3) has also shown efficacy in other malignancies, particularly multiple myeloma and myelodysplastic syndromes. Therapeutic doses of As(2)O(3) are well tolerated, with no evidence of long-term toxicity. Adverse events include APL differentiation syndrome, electrocardiographic abnormalities, and mild elevations in liver enzymes. This review highlights trials investigating the role of As(2)O(3) in induction and consolidation for newly diagnosed APL, as well as its role in other hematologic malignancies. The chemistry, mechanisms of action, and clinical side effects of As(2)O(3) are also discussed.

Rapid and reliable confirmation of acute promyelocytic leukemia by immunofluorescence staining with an antipromyelocytic leukemia antibody: the M. D. Anderson Cancer Center experience of 349 patients

BACKGROUND

The authors evaluated the utility of immunofluorescence staining with an antipromyelocytic leukemia (anti-PML) antibody for patients with a suspected diagnosis of new or relapsed acute promyelocytic leukemia (APL) and correlated the findings with the results of other established diagnostic modalities.

METHODS

Bone marrow (BM) and/or peripheral blood (PB) smears from 349 patients in whom the diagnosis of APL was considered were assessed with the anti-PML antibody using immunofluorescence. The study group included 199 patients with confirmed APL and 150 with other conditions. The results of conventional cytogenetics, reverse transcription polymerase chain reaction (RT-PCR), and fluorescence in situ hybridization (FISH) performed on these patients were correlated with the PML results.

RESULTS

Among patients with confirmed APL, anti-PML antibody was positive in 182 of 184 BM and 32 of 33 PB smears. Conventional cytogenetics demonstrated t(15;17)(q22;q12) in 166 of 182 (91%) patients; 10 had a normal karyotype, 4 had insufficient mitoses to grow in culture, 1 was inconclusive, and 1 was 48, XX, +8, +8. Anti-PML staining was positive in 9 of 10 with a normal karyotype and in all 4 cases with insufficient mitoses. RT-PCR and FISH were positive for PML-retinoic acid receptor-alpha in 169 of 172 (98%) and 90 of 94 (96%) cases, respectively. Among the patients without APL, 148 of 150 (98.6%) were negative with anti-PML antibody. The sensitivity and specificity of the test were 98.9% and 98.7%, respectively.

CONCLUSIONS

PML immunofluorescence staining is a rapid (<4 hours turnaround time) and reliable frontline diagnostic approach that can facilitate initiation of targeted therapy, particularly in clinical settings where cytogenetic and molecular testing are not readily available.

The expression of p38, ERK1 and Bax proteins has increased during the treatment of newly diagnosed acute promyelocytic leukemia with arsenic trioxide

BACKGROUND

Promising reports exist regarding the use of arsenic trioxide (ATO) as first-line treatment in acute promyelocytic leukemia (APL). Although the in vitro effect of ATO is extensively studied, the in vivo mechanism(s) of ATO action is mostly unknown.

PATIENTS AND METHODS

Newly diagnosed APL patients were involved and received ATO (0.15 mg.kg/day) for 28 days as induction followed by consolidation therapy. Bone marrow (BM) aspirates were obtained on days 0, 14 and 28 of treatment for further molecular studies. Clinical findings and white blood cell counts were recorded as well.

RESULTS

Complete remission was observed in 17 (85%) patients with the median duration of 28 days (18-38) and cumulative dosage of median 280 mg (180-350). Hyperleukocytosis and APL differentiation syndrome (63%), gastrointestinal disorders (30%), liver enzyme elevation and night sweating (50%) were the most prevalent side-effects. The expression of Bax, ERK1 and p38 proteins and caspase-3 activity increased significantly in promyelocytes of BM aspirates at days 14 and 28 of induction therapy.

CONCLUSION(S)

These findings point toward the role of p38 and Bax in the induction of apoptosis, which was confirmed by increase in caspase-3 activity. However, the increase in ERK1 expression with regard to leukocytosis could translate to a proliferative/differentiation effect.

Single cycle of arsenic trioxide-based consolidation chemotherapy spares anthracycline exposure in the primary management of acute promyelocytic leukemia

PURPOSE Event-free survival following all-trans-retinoic acid (ATRA) -based therapy for acute promyelocytic leukemia (APL) averages 70% at 5 years. While arsenic trioxide (ATO) can induce remissions in 95% of relapsed patients, few studies have addressed the integration of ATO into the primary management of APL. This study examines the efficacy of a single cycle of ATO-based consolidation therapy in a treatment regimen designed to decrease exposure to other cytotoxic agents. PATIENTS AND METHODS After induction with ATRA and daunorubicin (DRN), untreated patients with APL received 3 days of cytarabine and DRN followed by 30 doses of ATO beginning on day 8. Molecular remitters received 2 years of risk-based maintenance therapy. Results Forty-one of 45 patients receiving induction therapy achieved remission; four patients died (one before treatment was initiated). Thirty-seven patients received consolidation and maintenance; of these one patient relapsed (CNS) and one died in remission during maintenance therapy (hepatic sickle cell crisis). With a median follow-up of 2.7 years, estimated disease-free survival was 90%; overall survival for all patients was 88%. Despite a total anthracycline dose of only 360 mg/m(2), cardiac ejection fraction decreased by > or = 20% in 20% of patients. CONCLUSION These data, combined with other recent studies using ATO in the primary management of APL, demonstrate the important role that ATO can play in the primary management of this curable disease. Future studies should continue to focus on reducing the toxicity of treatment without increasing the relapse rate.

How I treat acute promyelocytic leukemia

Acute promyelocytic leukemia is the first malignant disease highly curable with targeted therapy directed at a unique molecular abnormality. The characteristic bleeding diathesis is the most notorious manifestation of the disease, which historically has accounted for a high mortality rate during induction. Acute promyelocytic leukemia is one of the few hematologic diseases that must be recognized under the microscope by the practicing hematologist because early institution of all-trans retinoic acid (ATRA) at the first suspicion of the disease before confirmation of the diagnosis and aggressive blood product support are critical to reduce early mortality. ATRA plus anthracycline-based chemotherapy for induction and consolidation followed by maintenance ATRA with low-dose chemotherapy is currently the standard of care. However, the combination of ATRA and arsenic trioxide, with minimal chemotherapy to control leukocytosis, is very effective therapy for newly diagnosed patients. This combination may replace conventional approaches for most, if not all, patients in the very near future. Acute promyelocytic leukemia should be considered in any patient with newly diagnosed acute myeloid leukemia because the treatment is urgent and different from all other subtypes.

Effects of arsenic trioxide, all-trans-retinoic acid and dexamethasone on NB4 cell line

BACKGROUND AND THE PURPOSE OF THE STUDY

Experimental and preclinical observations have indicated that combination therapy with all-trans-retinoic acid (ATRA) and arsenic trioxide (ATO) may strongly enhance their therapeutic effects in the treatment of acute promyelocytic leukemia (APL). Whilst dexamethasone (Dex) is routinely used for the control of APL- differentiation syndrome, its effect on the pharmacodynamics of ATO is not clear. Therefore, in this study, effects of therapeutic concentrations of ATO, ATRA and Dex and their sequential usages on the proliferation, differentiation and apoptosis in t(15;17)-positive NB4 cells was investigated.

METHODS

Cells were treated with therapeutic concentrations of ATO, ATRA and Dex either as single or in combination and cell proliferation was assessed by XTT assay. Expression of CD11b as an indicator of cell differentiation and the percentage of 7-AAD positive cells as a marker of apoptosis were determined by flow cytometry.

RESULTS

ATO, but not ATRA and Dex, decreased proliferation of the cells dose-dependently. Pre-treatment of the cells with any of the drugs did not alter the effects of other drugs on the proliferation. Pre-treatments with Dex blocked the apoptotic effect of ATO (1 µM).

CONCLUSION

No improvement or antagonistic effects was observed with the pretreatment/ combination of the ATO and ATRA on the differentiation and apoptosis of the cells. It is possible that concomitant usage of Dex with apoptotic doses of ATO in APL patients counteract therapeutic effects of ATO.

Chemokine induction by all-trans retinoic acid and arsenic trioxide in acute promyelocytic leukemia: triggering the differentiation syndrome

In acute promyelocytic leukemia (APL), differentiation therapy with all-trans retinoic acid (ATRA) and/or arsenic trioxide can induce a differentiation syndrome (DS) with massive pulmonary infiltration of differentiating leukemic cells. Because chemokines are implicated in migration and extravasation of leukemic cells, chemokines might play a role in DS. ATRA stimulation of the APL cell line NB4 induced expression of multiple CC-chemokines (CCLs) and their receptors (> 19-fold), resulting in increased chemokine levels and chemotaxis. Induction of CCL2 and CCL24 was directly mediated by ligand-activated retinoic acid receptors. In primary leukemia cells derived from APL patients at diagnosis, ATRA induced chemokine production as well. Furthermore, in plasma of an APL patient with DS, we observed chemokine induction, suggesting that chemokines might be important in DS. Dexamethasone, which efficiently reduces pulmonary chemokine production, did not inhibit chemokine induction in APL cells. Finally, chemokine production was also induced by arsenic trioxide as single agent or in combination with ATRA. We propose that differentiation therapy may induce chemokine production in the lung and in APL cells, which both trigger migration of leukemic cells. Because dexamethasone does not efficiently reduce leukemic chemokine production, pulmonary infiltration of leukemic cells may induce an uncontrollable hyperinflammatory reaction in the lung.

Therapy-induced PML/RARA proteolysis and acute promyelocytic leukemia cure

Acute promyelocytic leukemia (APL) is characterized by a specific t(15;17) chromosomal translocation that yields the PML/RARA fusion gene. Clinically, besides chemotherapy, two drugs induce clinical remissions: retinoic acid (RA) and arsenic trioxide (As). Both agents directly target PML/RARA-mediated transcriptional repression and protein stability, inducing to various extent promyelocyte differentiation and clinical remission of APL patients. RA targets the RARA moiety of the fusion, whereas arsenic targets its PML part. PML/RARA expression in the mouse is sufficient to initiate APL. The RA-As association, which synergizes for PML/RARA degradation but not for differentiation, rapidly clears leukemia initiating cells (LIC), resulting in APL eradication in murine APL models, but also in several APL clinical trials. Cyclic AMP triggered PML/RARA phosphorylation also enhances RA-induced APL regression, PML/RARA degradation, and LIC clearance, raising new options for therapy-resistant patients. Although differentiation has a major role in debulking of the tumor, PML/RARA degradation seems to be the primary basis for APL eradication by the RA-As association. Oncoprotein degradation could be a general therapeutic strategy that may be extended beyond APL.

Comparison of clinical outcomes of patients with relapsed acute promyelocytic leukemia induced with arsenic trioxide and consolidated with either an autologous stem cell transplant or an arsenic trioxide-based regimen

In patients with relapsed acute promyelocytic leukemia (APL), the best consolidation regimen following induction of remission with arsenic trioxide (ATO) remains to be defined. Since January 2000, 37 patients with relapsed APL were treated at our center. The median age was 34 years (range, 6-57 years), and there were 20 males (54.1%). The median duration of first remission was 20.3 months (range, 2.9-81.2 months). Relapse was treated with single-agent ATO in 22 patients (59.5%), ATO+ATRA in 5 patients (13.5%), and ATO+ATRA + anthracycline in 10 patients (27%). Thirty-three patients (89%) achieved molecular remission after induction and a consolidation course. Fourteen patients opted to undergo autologous stem cell transplantation (SCT), and the remaining 19 patients received monthly cycles of ATO as a single agent (n=13) or ATO+ATRA (n=6) for 6 months. At a median follow-up of 32 months, the 5-year Kaplan-Meier estimate of event-free survival (EFS) was 83.33% +/- 15.21% in those who underwent autologous SCT versus 34.45% +/- 11.24% in those who did not (P=.001; log-rank test). Following remission induction with ATO-based regimens in patients with relapsed APL, consolidation with autologous SCT is associated with a significantly superior clinical outcome compared with ATO- and ATO+ATRA-based maintenance regimens.