Relapsed Acute Promyelocytic Leukemia Research Articles

Abstract 2291: Arsenic trioxide induces cell cycle arrest, apoptosis and MAPKinase signaling cascade in acute promyelocytic leukemia cells

Abstract Arsenic trioxide (ATO) has recently been successfully used in the treatment of all-trans retinoic acid resistant relapsing acute promyelocytic leukemia (APL) patients both alone or combination with other drugs. Its use as induction and consolidation therapy has resulted in complete remission rate of both de novo and relapsed APL patients. However, the detailed molecular mechanisms of its therapeutic action are poorly known. We have used human leukemia (HL-60) cells as a model to elucidate the anti-cancer properties of arsenic trioxide. We hypothesized that ATO arrests cell cycle progression of HL-60 cells at G1 phase and leading to cell death by intrinsic pathway of apoptotic signaling. To test the hypothesis, we used western blotting, confocal imaging and spectrofluoremetric techniques to identify detailed cellular and molecular mechanisms of ATO action in HL-60 cells. We found that the expression levels of pro-apoptotic molecules (Bax) and cytochrome C were up-regulated, while that of anti-apoptotic Bcl2 protein was down-regulated at 4 and 6mg/mL ATO doses significantly. We also found that ATO stimulates signaling molecules like P38, JNK in a dose dependent manner in HL-60 cells. Oxidative stress and related imbalance of pro- and anti-apoptotic molecules lead to change of mitochondrial membrane potential and opening of the mitochondrial membrane transition pores. Our confocal imaging data shows a clear translocation of Bax from cytosol to mitochondria and of cytochrome c from mitochondria to cytosol in ATO-treated cells. A dose-dependent decrease/drop-down in mitochondrial membrane potential was also observed in ATO-treated cells, as evidenced by JC-1 leveling and spectrofluoremetric potential recording. On the basis of these findings, we conclude that mitochondrial pathway of apoptosis plays a key role in ATO pharmacology and should be further assessed as a drug target in APL chemotherapy. Citation Format: Sanjay Kumar, Clement Yedjou, Paul B. Tchounwou. Arsenic trioxide induces cell cycle arrest, apoptosis and MAPKinase signaling cascade in acute promyelocytic leukemia cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2291. doi:10.1158/1538-7445.AM2014-2291

"Tear drops" in the cerebrospinal fluid: correct by scatter, but pathognomonic by site.

Extramedullary relapse in acute promyelocytic leukemia (APL) is rare, but occurs most commonly in central nervous system (CNS), generally in high-risk cases (total leucocyte count ≥10,000/µL, atypical morphology or disseminated intravascular coagulation at presentation), and concomitant with bone marrow (BM) relapse. Here we describe a case of APL who except for CD56 positivity was low-risk, but had a CNS relapse without concomitant BM involvement. Diagnosis of isolated CNS relapse was based on characteristic tear-drop pattern for CD45/side scatter plot on flow cytometry, a full compatible immunophenotype and cytomorphology in the cerebrospinal fluid. The case illustrates the value of the latter and the importance of including CD56 in risk assessment of APL. © 2014 Clinical Cytometry Society.

Contemporary treatment of APL.

Acute promyelocytic leukemia (APL) is characterized by coagulopathy, leukopenic presentation and sensitivity to anthracyclines, all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). For the last 25years, APL has been treated with a combination of ATRA and chemotherapy for induction followed by consolidation and maintenance therapy. This general treatment approach has resulted in cure rates of 80-90%. ATO, originally approved in relapsed APL, has been incorporated into contemporary upfront treatment regimens with excellent response rates. Recent studies show that most patients with APL can be cured with ATRA and ATO alone, eliminating cytotoxic chemotherapy and resulting in superior outcomes compared to standard treatment. We will herein review historical treatment of APL, treatment considerations in specific patient populations, and therapeutic updates.

Treatment of an Acute Promyelocytic Leukemia Relapse Using Arsenic Trioxide and All-Trans-Retinoic in a 6-Year-Old Child

In adult therapy, arsenic trioxide (ATO) and all-trans-retinoic acid (ATRA) are recognized as active treatment of relapsed acute promyelocytic leukemia (APL). The efficacy of this combination in pediatric APL has not yet been well established. We report the case of a 6-year-old girl with relapsed APL, with a PML-RARα mutation, treated with a combination of ATO and ATRA. Over a period of 5 months, she received in total, 75 doses of intravenous ATO and 40 doses of oral ATRA. Currently, 22 months after relapse, she is still in complete remission. Here, we describe treatment of a relapsed APL in a child with limited treatment of ATO and ATRA and review the literature.

Outcomes and prognostic factors of first relapsed acute promyelocytic leukemia patients undergoing salvage therapy with intravenous arsenic trioxide and chemotherapy

Arsenic trioxide (ATO) is an effective therapy for relapsed acute promyelocytic leukemia (APL) patients; however, the optimal treatment strategy remains unclear, and knowledge of the prognostic factors is still limited. We retrospectively analyzed the outcomes of 64 consecutive first relapsed APL patients (12 with molecular relapse and 52 with hematologic relapse). Patients received re-induction with intravenous ATO-based regimens. Patients who achieved a CR2 were offered further courses of alternating ATO/conventional chemotherapy with or without stem cell transplantation (SCT). With a median follow-up of 27 months (range, 6-57) in the molecular relapsed subgroup, the 3-year relapse-free survival (RFS) and overall survival (OS) rates were 81.5% and 100%, respectively. With a median follow-up of 38 months (range, 0-129) in the hematologic relapse group, the 3-year RFS and OS rates were 57.1% and 72.1%, respectively. Furthermore, in the hematologic relapse group, we compared the outcome between relapsed patients after previous ATO therapy (n = 20) with those who did not receive prior ATO therapy (n = 32). The CR2 rate was 80% (16/20) vs. 93.8% (30/32), (p = 0.189). However, the relapse rate was 68.8% (11/16) vs. 33.3% (10/30), (p = 0.03). The 4-year OS rate was 62.4% vs. 71.2%, (p = 0.816), and the 4-year RFS rate was 29.8% vs. 66.2% (p = 0.023). The results indicate that, irrespective of frontline therapy with ATO, salvage therapy with an ATO-based regimen remains effective. However, the long-term survival for those patients who received previous ATO-based treatment was inferior compared to those who did not receive prior ATO. In addition, the alternating ATO/chemotherapy strategy can be a post-remission treatment option in a subset of patients.

Delayed Hematopoietic Recovery After Autologous Stem Cell Transplantation In Patients Receiving Arsenic Trioxide-Based Therapy For Acute Promyelocytic Leukemia

Introduction Arsenic trioxide (ATO)-based therapy for acute promyelocytic leukemia (APL) is highly effective and has been incorporated into standard therapeutic algorithms for patients with newly diagnosed and relapsed disease. Therapy for patients with high-risk or relapsed APL also includes high-dose chemotherapy with autologous stem cell transplantation (autoSCT). Both treatments have independently been demonstrated to improve long-term disease-free survival; however, the use of ATO prior to autoSCT has not been well studied. We sought to determine whether use of ATO prior to autologous stem cell collection impacts hematopoietic recovery following autoSCT. Methods Clinical histories of 31 consecutive patients undergoing autoSCT for APL at our institution since 1994 were reviewed. Viable CD34-positive cell recovery from cryo-preserved autograft products was assessed by pre- and post-thaw 7-amino-actinomycin D (7-AAD) staining. Student's t-tests and chi-squared tests were used for statistical analyses. Results A total of 32 autoSCTs were performed in this population. Twenty-four transplants (75.0%) were performed for patients in first complete remission (CR1) versus 8 transplants (25.0%) for patients in second complete remission (CR2). Seven of the 32 transplants (21.8%) were performed for patients who received ATO therapy prior to autologous stem cell collection. One patient received ATO with initial induction and consolidation therapy, 1 patient received ATO with initial consolidation therapy only, and 5 patients received ATO with re-induction therapy for relapsed disease. A significantly higher proportion of patients who received ATO were transplanted in CR2 (71.5% vs 12.0%, p<0.01). There were otherwise no significant differences in clinical characteristics or risk features between the ATO pre-treated and the ATO-naïve transplant recipients, including: median age at diagnosis (45 years vs 44 years, p=0.62), median age at transplant (46 years vs 45 years, p=0.36), white blood cell count >10,000/uL at presentation (28.6% vs 45.8%, p=0.42), mean CD34-positive cells collected (94.5 x106/kg vs 69.9x106/kg, p=0.35), or mean CD34-positive cells infused (41.4x106/kg vs 39.7x106/kg, p=0.90). Four cases (12.5%) of delayed hematopoietic recovery were identified, defined as requiring >16 days after stem cell infusion to recover an absolute neutrophil count (ANC) >1,000/uL. Three of 7 patients (43%) who received prior ATO had delayed hematopoietic recovery, compared with 1 of 24 patients (4.2%) not previously treated with ATO (p<0.01). Compared to ATO-naïve patients, ATO-treated patients experienced significantly longer time to ANC recovery (mean 19.7 days vs 10.4 days, p<0.01; median 14 days vs 10 days). In addition, ATO-treated patients required significantly longer transplant hospitalizations (37.2 days vs 24.6 days, p<0.01). Platelet recovery, defined as a sustained platelet count >50,000/uL, was also significantly delayed in the ATO-treated group (198.8 days vs 36.5 days, p<0.01; median 81 vs 18 days). The only significant predictor of delayed hematopoietic recovery was prior treatment with ATO (75.0% vs 14.2%, p<0.01). Of 7 assessable APL patient samples, the mean viable CD34-positive cell recovery was 39 +/- 25.1%. This was significantly lower than the viable CD34-recovery (71.3 +/- 27.3%, p=0.02) evaluated in a random selection of 11 other cryo-preserved autologous stem cell products from patients with lymphoma (n=2) and multiple myeloma (n=9). Samples from 2 ATO-treated APL patients who experienced delayed hematopoietic recovery exhibited viable CD34-positive cell recoveries of only 3% and 26%. Conclusions There is an association between ATO exposure and delayed hematopoietic recovery after autoSCT for APL, but a causal relationship is not yet established. Because of the increasing frequency with which ATO is being used in the front-line treatment of APL, larger studies are warranted to validate these findings and to determine the potential mechanism of delayed hematopoietic recovery after autoSCT. Lower-than-expected viable CD34-positive cell recovery from APL patients suggests a possible detrimental contribution of prior ATO exposure. Our institution is now prospectively examining pre- and post-thaw CD34-positive cell recovery, viability, and colony-forming assays prior to autoSCT in patients who have previously received ATO. Disclosures: No relevant conflicts of interest to declare.

Acute promyelocytic leukemia relapsing into acute myeloid leukemia-M2 with normal cytogenetics

The use of all trans-retinoic acid (ATRA) and combination chemotherapy has made acute promyelocytic leukemia (APL) a potentially curable leukemia. Late sequelae of the treatment of APL have therefore become an important consideration in the overall treatment strategy. We report a patient with APL who achieved complete clinical and molecular remission after treatment with daunorubicin and ATRA. Three years later, she developed acute myeloid leukemia (AML), M2 subtype without any evidence of relapse of the APL clone. Karyotypic analysis showed a normal female karyotype.

Outcomes in Patients With Relapsed or Refractory Acute Promyelocytic Leukemia Treated With or Without Autologous or Allogeneic Hematopoietic Stem Cell Transplantation

Outcomes in patients with acute promyelocytic leukemia (APL) have improved; however, a significant number of patients still relapse despite receiving all-trans-retinoic acid (ATRA) and arsenic-based therapies. Outcomes of patients with relapsed APL who were treated at our institution (1980-2010) and who received HCT were compared with those who received chemotherapy (CT) only. Among 40 patients, 24 received HCT (autologous [auto] HCT, 7; allogeneic [allo] HCT, 14; both, 3); 16 received CT only. The median age at diagnosis was 36 years (range, 13-50 years), 31 years (range, 16-58 years), and 44 years (range, 24-79 years) for the auto-HCT, allo-HCT, and CT groups, respectively. Ten (100%) patients who received auto-HCT and 12 (71%) who received allo-HCT were in complete remission at the time of the HCT. The median follow-ups in the auto-HCT, allo-HCT, and CT groups were 74 months (range, 26-135 months), 118 months (range, 28-284 months), and 122 months (range, 32-216 months), respectively. Transplantation-related mortality (1 year) after auto-HCT and allo-HCT were 10% and 29%, respectively. The 7-year event-free survival after auto-HCT and allo-HCT was 68.6% and 40.6%, respectively (P= .45). The 7-year overall survival was 85.7%, 49.4%, and 40% in the auto-HCT, allo-HCT, and CT groups, respectively (P= .48). Both auto-HCT and allo-HCT are associated with durable remission and prolonged survival. All 3 strategies (auto-HCT, allo-HCT, CT) were found to be feasible in the relapsed APL setting and result in long-term disease control in selected patients. In this retrospective analysis, overall survival for patients who received HCT was not significantly better than patients who received CT only, but a trend toward better outcomes was seen in patients who underwent auto-HCT, although not statistically significant.

Phase 2 study of arsenic trioxide followed by autologous hematopoietic cell transplantation for relapsed acute promyelocytic leukemia

AbstractThe optimal treatments for relapsed acute promyelocytic leukemia (APL) remain equivocal. We conducted a phase 2 study to evaluate the efficacy and feasibility of a sequential treatment consisting of induction and consolidation with arsenic trioxide (ATO), peripheral blood stem cell (PBSC) harvest after high-dose cytarabine chemotherapy, and autologous hematopoietic cell transplantation (HCT). Between 2005 and 2009, 35 patients (26 with hematologic and 9 with molecular relapse) were enrolled. Induction therapy resulted in complete remission in 81% of those with hematologic relapse, and most patients became negative for PML-RARα after the first ATO consolidation course, but 4 remained positive. Administration of the second ATO consolidation course further decreased the transcript levels in 3 patients. In total, 25 patients proceeded to PBSC harvest, all of whom successfully achieved the target CD34+ cell doses, and 23 underwent autologous HCT with PML-RARα–negative PBSC graft. Posttransplant relapse occurred in 3 patients, and there was no transplant-related mortality. With a median follow-up of 4.9 years, the 5-year event-free and overall survival rates were 65% and 77%, respectively. These findings demonstrate the outstanding efficacy and feasibility of the sequential treatment featuring ATO and autologous HCT for relapsed APL. This study was registered at http://www.umin.ac.jp/ctr/ as #C000000302.

Multiple isolated extramedullary relapse of acute promyelocytic leukemia after allogeneic hematopoietic stem cell transplant: a case report and review of literature

Isolated extramedullary disease (EMD) is uncommon, especially in acute promyelocytic leukemia (APL) after allogeneic hematopoietic stem cell transplantation (HSCT). We review the literature and present a 32 year old woman with APL who developed multiple EMDs after allogeneic HSCT within the calvarium, and later found to have various isolated lesions including femur, humerus and thoraco lumbar vertebrae. She was treated with local radiotherapy (XRT) to EMD lesions, all-trans retinoic acid, arsenic trioxide and donor lymphocyte infusion at different time points in her clinical course, without success. Out of reported cases in clinical setting as ours, average onset of isolated EMD is 25 months and median survival 14 months. Effective treatment of isolated EMD after HSCT is not yet clear, but ATO in combination with local XRT, tamibarotene and second HSCT have shown good results in some reported cases, but accumulation of more cases is needed to elucidate optimal therapy in such setting.Electronic supplementary materialThe online version of this article (doi:10.1186/2193-1801-2-49) contains supplementary material, which is available to authorized users.

CNS Relapse in Acute Promyelocytic Leukemia: Incidence, Management and Outcome

Abstract 1489▪▪This icon denotes a clinically relevant abstract Background:A standardized approach to the diagnosis, prognosis and therapy of patients with APL and CNS involvement is limited by the rare nature of the complication. We report the incidence, risk factors, management and outcome of APL with CNS involvement at Stanford University and review the published cases in the literature during the prior three decades. Methods:Between 1983 and Jan 2012, 7 cases of APL with CNS involvement were identified at Stanford University and 65 in the literature during the same interval. All pts in the Stanford series received ATRA and anthracycline containing induction regimens followed by consolidation with anthracycline and cytarabine (7 pts), plus ATRA (5 pts), ATO (1 pt), or IT prophylaxis (1 pt). Five pts received maintenance with ATRA containing regimens in all cases (2 pts relapsed prior to starting maintenance). Median follow-up was 6 years. Results:Seventy-two relapses involving the CNS were seen after 1 to 50 months (median 8 months) and 61 (84.7%) occurred in CR1 with 8 (11.1%) in CR2, 2 (2.8%) in CR3 and 1 (1.4%) in CR4. Forty-seven (66.2%) were accompanied by bone marrow involvement, 14 (29.8%) molecular and 33 (70.2%) hematological. Median age was 35y with 9 pediatric pts (range 1.3 to 20y) and 63 adult pts (range 22 to 69y). Median WBC count was 28,100 cells/mm3 (range 1,100 to 162,000 cells/mm3) with 61.4% >10 and 6.8% >100 cells/mm3. PML/RARα isoform was reported in 29 pts with 37.9% bcr1, 3.4% bcr2, and 58.6% bcr3. Five pts presented with concurrent CNS-localized hemorrhage. Therapy included methotrexate (88.9%), cytarabine (80.6%), arsenic trioxide (ATO, 47.2%), and anthracycline (11.1%) containing regimens with 88.9% receiving intrathecal therapy. Eighty-six percent received cranial radiation with dose ranging 18 to 30 Gy. Autologous or allogeneic transplantation followed salvage therapy in 30.8% and 5.6% of pts, respectively. Fifty-four (75.0%) pts were salvaged successfully, including 88.2% of pts receiving ATO, however 18 (33.3%) pts later relapsed, 4 (22.2%) of which were salvaged with additional treatment. Conclusion:CNS relapse is a rare complications of APL with the majority of cases occurring in pts with WBC >10 cells/mm3, and in first CR. CNS relapse was frequently associated with concurrent bone marrow relapse and approximately one-third occurred with only molecular involvement. A preventative role of IT prophylaxis could not be determined due to only 1 pt receiving prophylaxis. A high percentage of pts salvaged with ATO achieved CR, supporting its therapeutic efficacy and ability to cross the blood brain barrier. Incorporation of ATO in first line therapy for APL may reduce the risk of CNS relapse. Disclosures:No relevant conflicts of interest to declare.

A Phase III Study of New Synthetic Retinoid Tamibarotene(Am80) Compared with ATRA in Maintenance Therapy for Newly Diagnosed Acute Promyelocytic Leukemia (APL): Japan Adult Leukemia Study Group (JALSG) APL204 Study

AbstractAbstract 410 Background:ATRA with anthracycline-based chemotherapy markedly improved the prognosis of APL, leading to disease free survival rates 70–80%. But continuous relapse in post-remission period has been a major problem. The role of maintenance therapy for patients in molecular remission after consolidation therapy is uncertain and previous study showed ATRA with or without 6-MP/MTX for 1 to 2 years would be the choice. JALSG APL204 study was intended to decrease the relapse rate in post remission period and applied new synthetic retinoid Tamibarotene (Am80) for maintenance therapy. Am80 is an oral synthetic retinoid with benzoic acid and RARα specific agonist invented in Japan in 1984. High differentiation potential and low affinity to cytoplasmic retinoic acid binding protein may contribute to a superior anti-APL cell effect than ATRA. Early phase II study showed CR rate was 58% for relapsed APL previously treated with ATRA (Blood 90:967–973, 1997). Furthermore Am80 has lower incidence of muco-cutaneous side effects because of no binding affinity to RARγ. Methods:APL204 study was designed as prospective randomized phase III trial comparing Am80 with ATRA in maintenance therapy. Patients (pts) with untreated PML/RARA positive APL between the age of 15 to 69 are eligible. Induction therapy was stratified according to the initial WBC counts: WBC <3,000/μl (Group A: ATRA only), 3,000/μl ≦ WBC <10,000/μl (Group B: ATRA and IDA/Ara-C: 2+5), WBC <10,000/μl (Group C ATRA and IDA/Ara-C: 3+7) and pts who experienced leukocytosis in each group were added chemotherapy (group D). Consolidation chemotherapy consisted of 3 courses containing MIT/Ara-C, DNR/Ara-C and IDA/Ara-C. Patients who achieved molecular remission after consolidation chemotherapy were randomly assigned to 2 groups of maintenance therapy with Am80 at a daily dose of 6 mg/m2 divided in 2 doses for 14 days and ATRA at a daily dose of 45 mg/m2 divided in 3 doses for 14 days. Each cycle was repeated every 3 months for 2 years and MRD was monitored every 6 months for additional 2 years. Primary endpoint is hematological or molecular relapse-free survival (RFS) during maintenance and follow up period. Results:Between April 2004 to December 2010, 347 pts were enrolled and 345 pts were evaluable. Median age was 48 (range 16–68) years old, male : female = 183 : 162 and M3 : M3v = 322 : 23. Median WBC count at diagnosis was 700 (70–127,000)/μl and number of pts in each induction group were A=133, B=56, C=70, D=86 pts. In induction therapy, overall CR rate was 94.5% (326/345) and 95.5%(A), 92.9%(B), 88.6%(C), 98.8%(D) in each group. During consolidation therapy 11 pts (3.4%) were dead, including 9 pts (2.8%) for therapy related toxicity and 2 pts (0.6%) for resistant disease. Two hundred and seventy pts (85.7%) were evaluable for maintenance randomization, 134 pts in Am80 and 136 pts in ATRA. With median follow up of 51 (15–97) months, 5-year RFS was 90.9% (Am80) and 83.2% (ATRA) (P=0.1284), OS 92.4% and 98.1% (P=0.3543) in each group. In group C (WBC ≧10,000/μl), 5-year RFS was 87.7% (Am80) and 59.9% (ATRA) (P=0.0297), it was statistically significant, but in group A and B there was no significant differences. Overall relapse rate was 13.7% (37 pts) after randomization. The most frequent adverse effect of Am80 was a transient hyperglycemia. For all patients in APL204 study, 5-year EFS were 76.6%, RFS 82.9%, OS 87.5%. Conclusions:Maintenance therapy with Am80 has a moderate effect to decrease the relapse rate compared with ATRA but the difference was not statistically significant at 5 years. Both ATRA and Am80 maintenance seem to be effective compared to our previous APL97 study. Notably Am80 is significantly effective in high risk group as WBC ≧10,000/μl (Group C). These results may lead to new strategy for high risk APL. In the future study applying ATO in consolidation therapy and Am80 in maintenance therapy may be a promising strategy to improve the curability and decrease the toxicity of therapy for newly diagnosed APL. This trial was registered at University Hospital Medical Information Network (UMIN)-CTR ID C000000154 in Japan. Disclosures:No relevant conflicts of interest to declare.

ATRA and Arsenic Trioxide (ATO) Versus ATRA and Idarubicin (AIDA) for Newly Diagnosed, Non High-Risk Acute Promyelocytic Leukemia (APL): Results of the Phase III, Prospective, Randomized, Intergroup APL0406 Study by the Italian-German Cooperative Groups Gimema-SAL-AMLSG

AbstractAbstract 6 BackgroundSimultaneous ATRA and chemotherapy (CHT) is the current gold standard for newly diagnosed APL resulting in ∼80% cure rates, while arsenic trioxide (ATO) is the treatment of choice for relapsed patients. ATO in variable combinations including ± ATRA ± CHT has also been tested as front-line therapy yielding encouraging results in several pilot studies as well as in two phase III studies conducted in China and the US. So far, no randomised studies have compared front-line CHT-free ATO+ATRA combination against the standard ATRA+CHT approach. Patients and MethodsThe phase III, randomised, prospective APL0406 trial was started in October 2007 by the Italian GIMEMA group and joined in November 2008 by the German SAL and AMLSG multicenter groups. Eligible patients were adults aged 18-<71 years with newly diagnosed, genetically confirmed, non-high-risk (WBC≤10×109/L) APL. Patients were randomized to receive the ATO+ATRA combination originally reported by the MD Anderson group (Estey et al. Blood 2006, arm A), or the Italian AIDA2000 risk-adapted protocol for non high-risk disease (arm B). Patients in arm A received ATO 0.15/kg plus ATRA 45 mg/m2 daily until CR, then ATO 5 days/week, 4 weeks on 4 weeks off, for a total of 4 courses and ATRA 2 weeks on and 2 weeks off for a total of 7 courses. Patients in arm B received the standard AIDA (ATRA+Idarubicin) induction followed by 3 cycles of anthracycline-based plus ATRA consolidation and low dose CHT and ATRA for maintenance as reported (Lo-Coco et al., Blood 2011). The primary study objective was EFS at 2 years. The study was designed to show that the rate of patients alive event-free at two years in the experimental treatment arm is at least 80%. Secondary objectives included OS, DFS, CIR rates, molecular response and toxicity profile. ResultsFrom October 2007 to September 2010, the required sample size of 162 enrolled patients was completed. Median age was 45.3 years (18.7–70.2 years) and median WBC 1.50 × 109/L. As to the Sanz’s risk score, 61.8% and 38.2% of patients were in the intermediate- and low-risk categories, respectively. The two treatment arms were well balanced for main baseline characteristics including age, sex, median WBC and Sanz’s score. Eight patients were not evaluable for induction due to ineligibility or protocol violation. Of 154 patients evaluable for response to induction, CR was achieved in 150 (97.4%): 75/75 (100%) in arm A vs 75/79 (95%) in arm B (P=0.12). After a median follow-up of 31 months (range 0.07–50.4) the 2 year EFS (primary objective) was 97% (C.I.95%: 93.1–100) and 86.7% (C.I.95%: 80.3–93.6) in arms A and B respectively (P=0.03). There were 1 death in CR and 2 relapses in arm A, and 7 deaths (4 in induction, 3 in CR) and 4 relapses in arm B. As to secondary objectives, OS, DFS, and CIR rates were 98.7% vs. 91.1% (P=0.03), 97% vs. 91.6% (P=0.19) and 1.6% vs. 4.3% (P=0.41) in arm A and B, respectively. Fever episodes, prolonged (>15 d) grade ≥ 3 neutropenia and thrombocytopenia were significantly more frequent in patients in arm B as compared to those in arm A (P <.001 for all comparisons). Other side effects including differentiation syndrome and increase of liver enzymes were recorded with similar frequency in the two study arms. Two patients in arm A had QTc prolongation requiring ATO discontinuation with final withdrawal in one case. PCR analysis of PML/RARA (sensitivity 10−4) was centrally performed in Rome (F. Lo-Coco) and Dresden (C. Thiede) and showed molecular CR in 141/142 (99%) of evaluable patients after completion of 3rd consolidation. One patient in arm B who tested PCR-positive at this time point was considered resistant and taken off protocol as per study design. ConclusionsFor patients with newly diagnosed non-high-risk APL, as compared to the standard AIDA regimen, the front-line CHT-free ATO+ATRA combination is at least not inferior for 2 year EFS. [Display omitted] [Display omitted] Disclosures:Lo-Coco:Boehringer Ingelheim: Membership on an entity's Board of Directors or advisory committees; Cephalon: Speakers Bureau. Off Label Use: Arsenic Trioxide (ATO) is currently approved for therapy of relapsed APL in the US and Europe. In this study the role of ATO in front-line therapy of APL is explored. Fiedler:Pfizer Inc.: Consultancy, Research Funding; Novartis: Consultancy, Research Funding. Breccia:Celgene: Honoraria; Novartis: Honoraria; BMS: Honoraria. Platzbecker:GlaxoSmithKline: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Amgen: Consultancy.

Feasibility of oral arsenic trioxide treatment for acute promyelocytic leukemia during hemodialysis

Dear Editor, Arsenic trioxide (As2O3) is a standard medication for relapsed acute promyelocytic leukemia (APL). However, high blood arsenic levels lead to potentially fatal arrhythmias. As2O3 is renal-excreted and considered contraindicated in renal failure. A 42-year-old man was referred for treatment of APL in first relapse, presenting with pancytopenia, impaired renal function, and septicemia. He was treated with all-trans retinoic acid (ATRA, 45 mg/m2/day) and oral As2O3 (10 mg/day) [1]. Progressive renal function derangement developed, necessitating reduction of oral As2O3 to 5 mg/day. On the third day, the leukocyte count increased to 8.9 × 109/L, associated with bilateral pulmonary infiltrates. Features were consistent with the APL differentiation syndrome, which with the underlying septicemia led to anuric acute renal failure. ATRA was stopped. Idarubicin (6 mg/m2/day × 5), dexamethasone (12 mg/day × 7), and alternate daily hemodialysis were administered. Oral As2O3 at 5 mg was given after each hemodialysis and was stopped after 9 days. At 4 weeks, marrow examination confirmed complete remission. He remained anuric, and hemodialysis was continued. Oral As2O3 was re-commenced at 2 mg after each hemodialysis. Two months later, continuous ambulatory peritoneal dialysis (CAPD) was started. A maintenance regimen for APL, comprising oral As2O3 (5 mg/day) and ATRA (20 mg twice daily) [2, 3], given 2 weeks every 2 months, was administered. At 6-month follow-up, he remained in remission and was negative for the PML-RARA fusion gene characteristic of APL. No cardiac arrhythmias were observed at any time. Serum elemental arsenic levels were assayed by inductively coupled plasma mass spectrometry [3, 4], on blood samples sent for creatinine measurement. At 4 days, there was a sudden increase of arsenic levels, as the cellular and third-space compartments became saturated and anuria prevented arsenic excretion (Fig. 1a). The arsenic level peaked at 4,240 nmol/L, outside the therapeutic range of 500–2,000 nmol/L typical of oral As2O3. The commencement of hemodialysis and cessation of oral As2O3 resulted in a fall of arsenic levels parallel to those of creatinine. After oral As2O3 was re-commenced, arsenic levels gradually increased to the therapeutic range (Fig. 1b). As arsenic clearance in oral As2O3 therapy during CAPD had been documented previously [3], arsenic assays were not performed after peritoneal dialysis was started. Fig. 1 a Blood arsenic levels during the first 3 weeks of hemodialysis. A rapid surge of arsenic levels occurred on day 5, in parallel with a rise in creatinine and further renal function deterioration. Oral arsenic trioxide was stopped on day 9, resulting ... As2O3 is a key medication for patients with relapsed APL. Intravenous (i.v.) As2O3, used in most reports, may lead to lethal arrhythmias due to QT prolongation, which is directly proportional to blood arsenic levels [5]. Because i.v. As2O3 leads to a rapid surge of blood arsenic levels, arrhythmia related to QT prolongation is an important adverse effect. Oral As2O3 is slowly absorbed and results in lower blood arsenic levels. Its bioavailability, estimated by area-under-the-curve pharmacokinetically, is comparable to that of i.v. As2O3 [6]. Hence, oral As2O3 has the same efficacy, but little risk of arrhythmia [5]. In one previous report, blood arsenic levels after i.v. As2O3 were measured in an APL patient on hemodialysis [7]. The peak level was 6,450 nmol/L, a toxic level that led to termination of i.v. As2O3 therapy. It was concluded that i.v. As2O3 was contraindicated in renal failure [7]. In our case, the sudden increase in blood arsenic levels was related to an unanticipated acute renal failure. Timely cessation of oral As2O3 and institution of hemodialysis prevented further increases in arsenic levels. Subsequently, with careful dose adjustment and meticulous monitoring, oral As2O3 was safely administered during hemodialysis. The blood arsenic levels were also kept within the therapeutic range. We have also previously demonstrated the safety of oral As2O3 during CAPD. Therefore, patients on renal replacement therapy are still eligible for oral As2O3 treatment.

Late Relapse of Acute Promyelocytic Leukemia: Literature Review and Results of Seven Years of Clinical and Laboratory Follow-Up of a Korean Patient

Among patients with acute promyelocytic leukemia (APL), 10% to 30% experience relapse. Most relapses occur within 2 years; only a few, known as late relapses, occur 4 years after achievement of the first complete remission (CR). We present a rare case of an ethnic Asian patient with APL who experienced late relapse, which has been continuously monitored by reverse transcription polymerase chain reaction (RT-PCR) for long-term molecular remission. Recently, the European APL Group published 2 large-scale studies related to laterelapse APL; however, only 2 Asian cases of late-relapse APL had previously been documented in the literature. We consider this case to be the first report of a patient with late-relapse APL in South Korea and believe that future studies of late-relapse APL for Asian and other ethnic groups are necessary.

Arsenic Trioxide (ATO) Influences the Gene Expression of Metallothioneins in Human Glioblastoma Cells

Arsenic trioxide (As(2)O(3); ATO, TRISENOX®) is used to treat patients with refractory or relapsed acute promyelocytic leukaemia while its application for treatment of solid cancers like glioblastoma is still under evaluation. In the present study, we investigated the interaction of arsenic trioxide with metallothionein (MT) isoforms as a possible (protective response) resistance of glioblastoma cells to arsenic-induced cytotoxicity. Special attention was focused on MT3, the isoform expressed mainly in the brain. MT3 has low metal inducibility, fast metal binding/releasing properties and outstanding neuronal inhibitory activity. The human astrocytoma (glioblastoma) cell line U87 MG was treated with 0.6, 2 and 6-7 μM arsenic (equivalent to 0.3, 1 and 3-3.5 μM As(2)O(3)) for 12, 24 or 48 h and gene expression for different MT isoforms, namely MT2A, MT1A, MT1F, MT1X, MT1E and MT3, was measured by real time qPCR using SYBR Green I and Taqman® gene expression assays. TfR, 18S rRNA, GAPDH and AB were tested as reference genes, and the last two evaluated to be appropriate in conditions of low (GAPDH) and high (AB) arsenic exposure. The gene expression of MT3 gene was additionally tested and confirmed by restriction enzyme analysis with PvuII. In the given conditions the mRNAs of six MT isoforms were identified in human glioblastoma cell line U87 MG. Depending on arsenic exposure conditions, an increase or decrease of MT gene expression was observed for each isoform, with the highest increase for isoforms MT1X, MT1F and MT2A mRNA (up to 13-fold) and more persistent decreases for MT1A, MT1E and MT3 mRNA. Despite the common assumption of the noninducibility of MT3, the evident MT3 mRNA increase was observed during high As exposure (up to 4-fold). In conclusion, our results clearly demonstrate the influence of As on MT isoform gene expression. The MT1X, MT1F and MT2A increase could represent brain tumour acquired resistance to As cytotoxicity while the MT3 increase is more enigmatic, with its possible involvement in arsenic-related induction of type II cell death.

Promyelocytic leukemia nuclear bodies support a late step in DNA double‐strand break repair by homologous recombination

The PML protein and PML nuclear bodies (PML-NB) are implicated in multiple cellular functions relevant to tumor suppression, including DNA damage response. In most cases of acute promyelocytic leukemia, the PML and retinoic acid receptor alpha (RARA) genes are translocated, resulting in expression of oncogenic PML-RARα fusion proteins. PML-NB fail to form normally, and promyelocytes remain in an undifferentiated, abnormally proliferative state. We examined the involvement of PML protein and PML-NB in homologous recombinational repair (HRR) of chromosomal DNA double-strand breaks. Transient overexpression of wild-type PML protein isoforms produced hugely enlarged or aggregated PML-NB and reduced HRR by ~2-fold, suggesting that HRR depends to some extent upon normal PML-NB structure. Knockdown of PML by RNA interference sharply attenuated formation of PML-NB and reduced HRR by up to 20-fold. However, PML-knockdown cells showed apparently normal induction of H2AX phosphorylation and RAD51 foci after DNA damage by ionizing radiation. These findings indicate that early steps in HRR, including recognition of DNA double-strand breaks, initial processing of ends, and assembly of single-stranded DNA/RAD51 nucleoprotein filaments, do not depend upon PML-NB. The HRR deficit in PML-depleted cells thus reflects inhibition of later steps in the repair pathway. Expression of PML-RARα fusion proteins disrupted PML-NB structure and reduced HRR by up to 10-fold, raising the possibility that defective HRR and resulting genomic instability may figure in the pathogenesis, progression and relapse of acute promyelocytic leukemia.

Speciation of arsenic trioxide metabolites in peripheral blood and bone marrow from an acute promyelocytic leukemia patient

BackgroundSpeciation of arsenic trioxide (ATO) metabolites in clinical samples such as peripheral blood (PB) from acute promyelocytic leukemia (APL) patients has been conducted. However, speciation of arsenicals in bone marrow (BM) has not yet been performed. Profiles of arsenic speciation in plasma of BM were thus investigated and compared with those of PB plasma from a relapsed APL patient. The total arsenic concentrations in high molecular weight fraction (HMW-F) of BM and PB plasma were also determined.MethodsResponse assessment was evaluated by BM aspirate examination and fluorescence in situ hybridization analysis. The analyses of total arsenic concentrations and speciation were preformed by inductively coupled plasma mass spectrometry (ICP-MS), and high-performance liquid chromatography (HPLC)/ICP-MS, respectively.ResultsResponse assessment showed that the patient achieved complete remission. The total arsenic concentrations in BM plasma increased with time during the consecutive administration. The PB plasma concentrations of methylated arsenic metabolites substantially increased after the start of administration, while those of inorganic arsenic were still kept at a low level, followed by substantially increase from day-14 after administration. The arsenic speciation profiles of PB plasma were very similar to those of BM plasma. Furthermore, the total arsenic concentrations of HMW-F in BM plasma were much higher than those in PB plasma.ConclusionsThe behaviors of arsenic speciation suggested for the first time that arsenic speciation analysis of PB plasma could be predicative for BM speciation, and showed relatively higher efficiency of drug metabolism in the patient. These results may further provide not only significance of clinical application of ATO, but also a new insight into host defense mechanisms in APL patients undergoing ATO treatment, since HMW proteins-bound arsenic complex could be thought to protect BM from the attack of free arsenic species.

Extremely Late Extramedullary Relapse of Acute Promyelocytic Leukemia, Case Report and Review of the Literature

With the use of all-trans retinoic acid (ATRA) as frontline treatment for acute promyelocytic leukemia (APL), there has been an increase in overall remission rates and extended survival, but relapses still occur. While most cases of relapse are limited to the bone marrow and/or blood, APL can relapse in extramedullary sites as well. These relapses may develop several years after remission. While different reasons for extramedullary relapse have been presented in the literature, the exact mechanism and reason for late relapse still needs to be defined. Our case documents the longest interval from diagnosis to relapse of APL described in the literature to date. doi: http://dx.doi.org/10.4021/jh41e

TREATMENT OF ACUTE PROMYELOCYTIC LEUKEMIA WITH SINGLE-AGENT ARSENIC TRIOXIDE

It is well recognized that arsenic trioxide (ATO) is an efficacious agent for the treatment of acute promyelocytic leukemia (APL). Use of single agent ATO in the treatment of APL leads to remissions which are durable in the majority. ATO is probably the most effective single agent in the treatment of APL and there have been very few reports of primary resistance. It has been used both as a single agent and in combination with other conventional drugs to treat APL. Use of ATO is the accepted standard of care in the management of relapsed APL, where it is often used effectively as a bridge to a stem cell transplant. However, its role in newly diagnosed APL remains controversial. ATO probably has multiple mechanisms of action. Better understanding of its mechanisms of action/s is likely to lead to more rationale use of this agent or its derivatives either alone or in combination with other drugs. There is limited data on the kinetics of leukemia clearance and normal haematopoietic recovery after the administration of single agent ATO for the treatment of APL, preliminary data suggests that it is likely to be different from conventional therapy. There have been a number of concerns of the potential short and long term toxicity of this agent. Most such concerns arise from the toxicity profile noted in people exposed to long term arsenic exposure in the environment. With the therapeutic doses and schedules of administration of ATO in the treatment of malignancies the overall toxicity profile has been favorable. In a resource constrained environments the use of a single agent ATO based regimen is a realistic and acceptable option to treat almost all patients. In the developed world it has the potential in combination with other agents to improve the clinical outcome with reduction of dose intensity of chemotherapy and remains an option for patients who would not tolerate conventional therapy. In this review we focus on the use of single agent ATO for the treatment of APL and summarize our experience and review the literature.