International Consortium On Acute Promyelocytic Leukemia Research Articles

Cost-Effectiveness of the Regimen Proposed By the International Consortium on Acute Promyelocytic Leukemia in the Treatment of Newly Diagnosed Patients with Acute Promyelocytic Leukemia

Introduction Acute promyelocytic leukemia (APL) is distinguished by the presence of a translocation between chromosomes 15 and 17 [t(15;17)]. All-transretinoic acid (ATRA) plus arsenic trioxide (ATO) is considered as the first line treatment of APL, and can induce a complete remission (CR) in greater than 90% of patients, with a 2-year overall survival (OS) of 99% (Lo-Coco et al, N Eng J Med, 2013). Due to the high treatment costs of this regimen, the International Consortium on Acute Promyelocytic Leukemia (IC-APL) developed a protocol to diminish the economic burden associated with the treatment of APL (Ribeiro & Rego, Hematol Am Soc Hematol Educ Progr, 2006). We performed a cost-effectiveness analysis (CEA) and a cost-utility analysis (CUA) of the IC-APL protocol in Mexico, and compared it with the costs of the first line treatment of this disease in other countries.Methods We compared the patients in our institute, which were treated with the IC-APL protocol, with patients treated at other institutions with the first line treatment. For the CEA, the CR was compared with the cost of each protocol, and then compared by using the incremental cost-effectiveness ratio (ICER); for the CUA the quality-adjusted life years (QALY) were obtained and compared with the cost of each protocol, and then compared by using the incremental cost-utility ratio (ICUR).Results CR was achieved in 18 patients (90%) treated with the IC-APL protocol as a first line option; only 1 patient (5%) died in induction; of the patients that achieved CR, 1 relapsed (5.5%). The mean estimated OS was89 months (CI 95%; 86.619 - 101.515), with 89% of patients alive at 39 months; the mean estimated disease free survival (DFS) was 91 months (CI 95%; 83.711 - 99.818), with 94% of patients free of disease at 24 months. The median treatment cost of the IC-APL protocol was $ 21 369 USD. The median length of treatment was 29 months (range, 27 - 39 months), with a median of life without treatment of 41 months (0 - 68 months). The average number of years of life was 7.84 years, with the average QALY of 6.1 (table 1). The total cost of ATRA + ATO in Italy was $ 60 354 USD, in Canada $ 124 108 USD (QALY of 14.68) and in the USA $ 136 170 USD (QALY of 14.33). The CEA yielded $227, $603, $1241 and $1351 USD per % of CR in Mexico, Italy, Canada and the USA, respectively. When comparing the ICER between the IC-APL and the ATRA+ATO protocols, we found a difference of $6 497, $19 133 and $17 123 USD in Italy, the USA and Canada, respectively (table 2) In relation to the CUA, each QALY gained in Mexico costs $3 500 USD, in Canada $11 979 USD, and in the USA $13 955 USD. When comparing the ICUR between the IC-APL and the ATRA+ATO protocols, we founda difference of $13 955 and of $19 133 and of $11 979 USD in the USA and Canada, respectively (table 3).Conclusion Similar clinical endpoints were achieved with the IC-APL protocol when compared with first line treatment, with better outcomes in the cost-effectiveness and cost-utility analyses. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Stathmin 1 Is Highly Expressed in Acute Promyelocytic Leukemia and Microtubule Dynamics Is a Potential Target for ATRA-Resistant APL Cells

Introduction : Stathmin 1 is a microtubule destabilizer protein involved in the proliferation and differentiation of early hematopoietic progenitors. Aberrant Stathmin 1 expression has been reported in hematological malignancies. Stathmin 1 silencing reduces cell proliferation and clonogenicity of leukemia cell lines. A previous study identified that the PML-RARα fusion protein, which is necessary to acute promyelocytic leukemia (APL) genesis, positively regulates Stathmin 1 at transcription and protein activity levels. However, Stathmin 1 expression and its impact on prognosis and leukemia cell biology have rarely been studied in APL. Objectives : To evaluate Stathmin 1 expression and its association with laboratory and clinical parameters in a cohort of APL patients. To investigate Stathmin 1 expression and activity upon all-trans retinoic acid (ATRA) treatment and during cell cycle in the PML-RARα cell lines. Finally, to phenocopy the effects of Stathmin 1 inhibition using the pharmacological microtubule stabilizing agent paclitaxel. Methods : Bone marrow samples from 121 APL patients enrolled in the International Consortium on Acute Promyelocytic Leukemia (IC-APL) at diagnosis and 22 healthy donors were included. Patients were treated with ATRA and chemotherapy as described elsewhere. Patients were dichotomized according to Stathmin 1 expression using the median as cut-off. The PML-RARα cell lines, NB4 (ATRA-sensible) and NB4-R2 (ATRA-resistant) were used for functional assays. Cell cycle was synchronized by double thymidine block. For dose-response curves (MTT), PML-RARα cells were treated with graded concentrations of paclitaxel and IC50 values were calculated using a nonlinear regression analysis. For apoptosis assay (annexin V/PI), PML-RARα cells were treated with ATRA (1 µM) and/or IC50 paclitaxel dose for 72 hours. Gene and protein expressions were evaluated by qPCR and Western blot, and microtubule networks by confocal microscopy. For statistical analyses, Fisher's exact test or Chi-square test were used to compare categorical variables. Mann-Whitney test, t Student test or ANOVA test and Bonferroni post-test were used to compare continuous variables. Log-rank test and Cox regression were used for survival analyzes. P -value <0.05 was considerate statistically significant. Results : Stathmin 1 transcripts were significantly increased in bone marrow samples from APL patients compared with healthy donors (median 1.21 [range 0.02-4.62] versus (vs.) 0.66 [0.01-1.71]; p <0.01). Stathmin 1 levels did not impact on disease-free survival, overall survival and complete remission rates of APL patients. No relevant association between Stathmin 1 expression and clinical and laboratory parameters were observed. In NB4 cells, but not in NB4-R2, ATRA induced granulocytic differentiation, associated with a prominent reduction of Stathmin 1 gene and protein expression (p <0.05). Paradoxically, ATRA-induced granulocytic differentiation strongly reduced α-tubulin acetylation (microtubule stability marker) in NB4 cells. Using thymidine-synchronized cells, we observed that Stathmin 1 phosphorylation at serine 16 (an inhibitory site) was predominant in pool of mitosis-enriched cells, and its phosphorylation was marked reduced in pool of G1-enriched cells. NB4 and NB4-R2 cells presented high sensibility to paclitaxel treatment (IC50 of 3.6 nM and 1.8 nM, respectively). In NB4-R2 cells, but not in NB4 cells, paclitaxel increased the number of apoptotic cells after 72 hours of ATRA treatment; increased annexin V and caspase 3 cleavage (p <0.05). Paclitaxel treatment increased acetyl-α-tubulin, y-H2AX and CDKN1A levels. Conclusions : Stathmin 1 is highly expressed, but does not impact clinical outcomes in APL patients. Stathmin 1 reduces during ATRA-induced cell differentiation. Stathmin 1 activity is reduced during mitosis (as demonstrate by increased p-Stathmin 1S16) and increases post-mitosis (reduced p-Stathmin 1S16), indicating that this protein participates in microtubule dynamics and cell cycle progression in PML-RARα cells. Paclitaxel was an efficient pharmacological agent in inducing microtubule stabilization, reducing cell viability, increasing mitotic catastrophe as monotherapy or in combination with ATRA, in PML-RARα cells, including ATRA-resistant cells. Our study provides new insights on Stathmin 1 and microtubule dynamics in APL. DisclosuresBittencourt:Janssen, Takeda: Honoraria.

Impact of the ICAL on the treatment of acute leukemia

The International Consortium on Acute Promyelocytic Leukemia (IC-APL) is an initiative of the International Members Committee of the American Society of Hematology, created in the spirit of international clinical and laboratory collaboration with the aim of reducing the difference in the outcomes of

High ΔNp73/TAp73 ratio is associated with poor prognosis in acute promyelocytic leukemia

AbstractThe TP73 gene transcript is alternatively spliced and translated into the transcriptionally active (TAp73) or inactive (ΔNp73) isoforms, with opposite effects on the expression of p53 target genes and on apoptosis induction. The imbalance between ΔNp73 and TAp73 may contribute to tumorigenesis and resistance to chemotherapy in human cancers, including hematologic malignancies. In acute promyelocytic leukemia (APL), both isoforms are expressed, but their relevance in determining response to therapy and contribution to leukemogenesis remains unknown. Here, we provide the first evidence that a higher ΔNp73/TAp73 RNA expression ratio is associated with lower survival, lower disease-free survival, and higher risk of relapse in patients with APL homogeneously treated with all-trans retinoic acid and anthracycline-based chemotherapy, according to the International Consortium on Acute Promyelocytic Leukemia (IC-APL) study. Cox proportional hazards modeling showed that a high ΔNp73/TAp73 ratio was independently associated with shorter overall survival (hazard ratio, 4.47; 95% confidence interval, 1.64-12.2; P = .0035). Our data support the hypothesis that the ΔNp73/TAp73 ratio is an important determinant of clinical response in APL and may offer a therapeutic target for enhancing chemosensitivity in blast cells.

Feasibility of Implementing Minimal Residual Disease Monitoring in Acute Promyelocytic Leukemia Patients Treated in Developing Countries

Minimal Residual Disease (MRD) monitoring is recognized as a clinically useful tool for the management of Acute Promyelocytic Leukemia (APL) and has been performed by reverse transcriptase Polymerase Chain Reaction (RT-PCR) and Real-Time Quantitative Polymerase Chain Reaction (RQ-PCR). The vast majority of the published studies were conducted in developed countries within well established clinical trials, but the feasibility of MRD monitoring in developing countries is controversial. Here we describe the experience of Brazilian centers that participated in the International Consortium on Acute Promyelocytic Leukemia (IC-APL). In the present study, the participating centers were located at distances up to 2.500 km of central national laboratory and delivery sample time is less than two days. The aim of this study was to determine the feasibility and compare the effectiveness of RQ-PCR and RT-PCR in the MRD research in the context of IC-APL. We analyzed 398 bone marrow (BM) samples from 74 Brazilians patients with de novo APL; mean follow-up of 18 months. Samples were collected at diagnosis (n=74), at post-induction (n=48) after the third consolidation (n=41), and at maintenance (n=235). Standardized assays developed by Europe Against Cancer (EAC) program were used. Clinical characteristics were similar among the full cohort (patients from Brazil [n=122], Mexico [n=30], Chile [n=23], Uruguay [n=8]). Thirty-nine (52%) patients were classified as intermediate risk. PML breakpoint was bcr1 (n=45), bcr2 (n=1), and bcr3 (n=27). The median NCN of transcripts at diagnosis was 0.5151 (n=41) and 0.4690 (n=27) for the bcr1 and bcr3 subtypes, respectively. At the end of induction, there was a reduction of about 3 logs (0.0004 for bcr1 and 0.0005 for bcr3). In this stage, six discrepant cases were observed, all positive by RQ-PCR. There were no relapsed cases. 66/74 (89%) patients completed induction phase and achieved complete remission, and 8/74 (10%) died of hemorrhagic causes. The rate of molecular remission in our study was 37.5% (18/48) by RQ-PCR and 50% (24/48) by RT-PCR. Considering samples obtained at the end of consolidation phase, one discrepant result was detected as negative by RT; however it was not confirmed by RQ-PCR. Both cases did not relapse. The analysis for RQ-PCR was performed in 64% (41/64) of samples. Two patients have died of infectious diseases during the consolidation phase. All patients achieved molecular remission based on the results of RT-PCR. One patient was positive by RQ-PCR (NCN: 0.00006), but all subsequent samples were negative for both techniques, and the patient is alive, in remission. The median NCN of all samples after the third consolidation phase was 0.00001 PML-RARA/104 copies of ABL copies, regardless of the breakpoint. Within 53 patients who have completed the third cycle of consolidation, only 48 started the maintenance. 235 samples were evaluated during maintenance; 87.6% (206/235) were negative by RQ-PCR technique and 94.4% (222/235) by RT-PCR. The median NCN of all samples in the maintenance was 0.00001 PML-RARA/104 copies of ABL copies. The RQ-PCR technique proved to be predictive of relapse in three out of four cases of molecular relapse. All three cases showed positive results for RT-PCR during the early stages of the maintenance cycle and were confirmed by a second sample taken within 15 days. These results are confirmed in literature, observing that most patients who had negative PCR after consolidation relapsed after few months. In one case of molecular relapse, the RQ-PCR analysis provided much earlier warning of recurring disease, testing positive 5 and 6 months, respectively, before documentation of molecular relapse by conventional RT-PCR assay. In two cases, the negative result was performed by RT-PCR post induction, and was not confirmed by RQ-PCR, which remained positive on subsequent samples, and was confirmed once by RT-PCR after long time. According to transcripts numbers at maintenance, there was a decrease of approximately 5 logs when compared to samples after third consolidation. RQ-PCR technique was more sensitive than RT-PCR, providing earlier warning of relapse, thereby allowing greater opportunity for successful delivery of pre-emptive therapy. In sum, the implementation of the IC-APL allowed the improvement of laboratory standards in parallel to advances in clinical management. DisclosuresNo relevant conflicts of interest to declare.

Prognostic Impact Of MLL5 transcript Levels On Outcome Of Patients With Acute Promyelocytic Leukemia Treated With All-Trans Retinoic Acid and Anthracycline-Based Chemotherapy: An International Consortium On Acute Promyelocytic Leukemia Study

BackgroundThe MLL5 gene encodes a histone methyltransferase implicated in positive control of several genes related to hematopoiesis. Its close relationship with retinoic acid–induced granulopoiesis suggests that the deregulated expression of MLL5 might lead acute promyelocytic leukemia (APL) blasts to become less susceptible to differentiation-inducing ATRA effects. Here, we retrospectively determined the MLL5 transcript levels in samples from APL patients enrolled in the International Consortium on Acute Promyelocytic Leukemia (IC-APL) trial and analyzed its relationship with clinical and laboratory features, hematologic recovery, relapse, and survival. The results of the IC-APL have been previously reported (Blood 2013, 121(11) pp: 1935). In brief, complete hematological remission (CR) was achieved by 153/180 patients enrolled in Brazil, Mexico, Chile and Uruguay and after a median follow up of 28 months, the 2-year cumulative incidence of relapse (CIR), overall survival (OS) and disease-free survival (DFS) were 4.5%, 80% and 91%, respectively.Design and MethodsOne hundred and twenty-one APL patients (age, 15-73y) from seven different Brazilian institutions and treated according to the IC-APL protocol were included. The treatment schedule was identical to that adopted in the PETHEMA/HOVON LPA2005 trial, except for the replacement of idarubicin by daunorubicin. ATRA treatment was initiated immediately in all cases in which the diagnosis of APL was suspected based on morphology. As normal controls, total bone marrow (BM, n=8) and peripheral blood (PB, n=101) cells from healthy donors (age, 18-60y) were collected and mononuclear cells were isolated by Ficoll-Hypaque density gradient centrifugation. Additionally, 28 CBF-leukemia samples were included. Gene expression profile was analyzed by real-time quantitative PCR using the ABL FusionQuant Standard Kit as an endogenous control. Based on the continuous distribution of MLL5/ABL expression on APL samples (Figure 1), we adopted the median value of MLL5/ABL expression as cut-off to dichotomize APL patients in “low” and “high” MLL5 transcript levels.ResultsMLL5 expression was not different between APL, CBF-leukemia and healthy donors samples (Figure 1; P=0.19). There was no relevant difference between APL patients with low (n=62) and high (n=59) MLL5 transcript levels with respect to clinical and laboratory features, although high MLL5 transcript levels were more likely to be present in female gender (P=0.029). Overall, 102 (84%) achieved CR. Patients with low MLL5 transcript levels had significantly lower CR rate than patients with high MLL5 transcript levels (74% vs 95%; P=0.002). Twelve patients (10%) experienced early mortality (i.e., death during induction therapy) due to hemorrhage (n=6; 50%), disease progression (n=1; 8.3%), thrombosis (n=1; 8.3%), therapy-related infection (n=3; 25%) and differentiation syndrome (n=1; 8.3%); MLL5 transcript levels had no impact on early mortality (P=0.155). With a follow-up of 33 months among survivors (range, 1-72 months), patients with low MLL5 transcript levels had significantly lower 2-year OS (P=0.005) and 2-year DFS rate (P=0.037) than patients with high MLL5 transcript levels. Up to January 2013, a total of six relapses (5%) had been recorded. The 2-year CIR among patients with low and high MLL5 transcript levels was 14% (95%CI: 5% to 27%) and 2% (95%CI: 0.1% to 11%), respectively (P=0.04). We have further evaluated the prognostic impact of MLL5 transcript levels in those patients who remain alive after induction therapy (107 patients). Low MLL5 transcript levels were predictive of lower CR rate (P=0.042) and 2-year OS rate (P=0.009), but had no impact on DFS (P=0.106).ConclusionOur results show that MLL5 transcript levels may predict lower remission rate, short survival and higher risk of relapse in APL patients treated with ATRA and anthracycline-based chemotherapy. This is the first report describing the MLL5 expression as a prognostic factor in APL; nevertheless, our results should be confirmed in an independent cohort. [Display omitted] [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Evaluation Of Seasonality In The Incidence Of Promyelocytic Leukemia In Brazil

Besides the known factors such as the presence of oncogenes, the macro-environment (pollution, infections) or organic microenvironment (dysregulation of the immune system) can be the triggering factor of the process of leukemogenesis. It is known that the amount of rainfall can affect the distribution (dilution) of pollutants in the air and water reserves. There is no description of the climate influence in the incidence of Acute Promyelocytic Leukemia (APL), which has its own clinical laboratory characteristics, and is defined by the presence of the PML-RARA rearrangement.The aim of this study was to investigate the impact of seasonality in the incidence of Promyelocytic Leukemia in Brazil, and its characteristics. Patients and methodswe analyzed the clinical laboratory data and origin of participant cases of the International Consortium on Acute Promyelocytic Leukemia (IC-APL), a group multicenter treatment of APL with standardized diagnosis and treatment. We included all patients diagnosed with APL of Brazilian centers between 2006 and 2011. We excluded patients without demographics. Patients were divided into macro-climate (Northeast, South and Southeast). Northeast: 49 cases of Pernambuco, Southeast: 16 cases of Minas Gerais, São Paulo 88 cases; South: 27 cases of Rio Grande do Sul and 19 cases of Paraná. Meteorological data were extracted from the database Meteorological Research and Education (BDMEP) of the National Institute of Meteorology (INMET), and grouped by quarter. We studied the mean maximum temperature, mean minimum temperature and rainfall. The relationship between the number of cases and meteorological data were analyzed by the Spearman test. ResultsWe included 149 patients with APL. In the South, there were 46 patients, 50% female and 50% male, mean age: 37 years, 16 cases occurred on the first quarter (January-March), 12 on the second quarter (April-June), 8 cases on third quarter (July-September) and 10 on the fourth quarter (October to December). In the Northeast, there were 49 cases, 25 female and 24 male, mean age 34 years with 11 cases on the first and second quarters, 12 cases on the third quarter and 15 cases on the fourth quarter. Southeast: 54 cases with 29 female cases and 25 male cases, mean age 25 years, with 12 cases on the first and second quarter, 11 cases on the third quarter and 19 cases on the fourth quarter. In the South, there was no statistically significant correlation between the weather and the number of registered cases of APL. In the Northeast, there was a negative correlation between the number of cases of APL and rainfall (r = -0.57, p = 0.004) and a trend with the maximum temperature (r = 0.34, p = .07). In the southeast, there was positive correlation between rainfall (r = 0.42, p = 0.02) but not with temperature. In the northeast, the smallest amount of rainfall is associated with higher temperatures (r = -0.49, p <0.0002), whereas in the Southeast, the greater amount of rainfall is associated with warmer temperatures. ConclusionThere is no known etiology of APL, but the correlations found between rainfall and number of cases could be related to the dispersion of pollutants into the environment. Disclosures:No relevant conflicts of interest to declare.

Improving acute promyelocytic leukemia (APL) outcome in developing countries through networking, results of the International Consortium on APL

AbstractThanks to modern treatment with all-trans retinoic acid and chemotherapy, acute promyelocytic leukemia (APL) is now the most curable type of leukemia. However, this progress has not yielded equivalent benefit in developing countries. The International Consortium on Acute Promyelocytic Leukemia (IC-APL) was established to create a network of institutions in developing countries that would exchange experience and data and receive support from well-established US and European cooperative groups. The IC-APL formulated expeditious diagnostic, treatment, and supportive guidelines that were adapted to local circumstances. APL was chosen as a model disease because of the potential impact on improved diagnosis and treatment. The project included 4 national coordinators and reference laboratories, common clinical record forms, 5 subcommittees, and laboratory and data management training programs. In addition, participating institutions held regular virtual and face-to-face meetings. Complete hematological remission was achieved in 153/180 (85%) patients and 27 (15%) died during induction. After a median follow-up of 28 months, the 2-year cumulative incidence of relapse, overall survival (OS), and disease-free survival (DFS) were 4.5%, 80%, and 91%, respectively. The establishment of the IC-APL network resulted in a decrease of almost 50% in early mortality and an improvement in OS of almost 30% compared with historical controls, resulting in OS and DFS similar to those reported in developed countries.

The results of the International Consortium on Acute Promyelocytic Leukemia: a 'proof of concept' of networking as a strategy to improve the outcome of treatment of hematological malignancies in developing countries.

The results of the International Consortium on Acute Promyelocytic Leukemia: a 'proof of concept' of networking as a strategy to improve the outcome of treatment of hematological malignancies in developing countries.

The impact of medical education and networking on the outcome of leukemia treatment in developing countries. The experience of International Consortium on Acute Promyelocytic Leukemia (IC-APL)

Objectives: Several clinical trials conducted in Europe and US reported favorable outcomes of patients with APL treated with the combination of all trans retinoic acid (ATRA) and anthracyclines. Nevertheless, the results observed in developing countries with the same regimen was poorer, mainly due to high early mortality mainly due bleeding. The International Consortium on Acute Promyelocytic Leukemia (IC-APL) is an initiative of the International Members Committee of the ASH and the project aims to reduce this gap through the establishment of international network, which was launched in Brazil, Mexico and Uruguay.Methods: The IC-APL treatment protocol is similar to the PETHEMA 2005, but changing idarubicin to daunorubicin. All patients with a suspected diagnosis of APL were immediately started on ATRA, while bone marrow samples were shipped to a national central lab where genetic verification of the diagnosis was performed. The immunofluorescence using an anti-PML antibody allowed a rapid confirmation of the diagnosis and, the importance of supportive measures was reinforced.Results: The interim analysis of 97 patients enrolled in the IC-APL protocol showed that complete remission (CR) rate was 83% and the 2-year overall survival and disease-free survival were 80% and 90%, respectively. Of note, the early mortality rate was reduced to 7.5%.Discussion: The results of IC-APL demonstrate the impact of educational programs and networking on the improvement of the leukemia treatment outcome in developing countries.

Comparison Between RT-PCR and RQ-PCR for Minimal Residual Disease Detection in Acute Promyelocytic Leukemia: The International Consortium on Acute Promyelocytic Leukemia (IC-APL) Experience,

Abstract 3552The International Consortium on Acute Promyelocytic Leukemia (IC-APL) is an initiative of the International Members Committee of the ASH that aims to improve the treatment outcome of acute promyelocytic leukemia (APL) patients in developing countries, which was launched in Mexico, Brazil, Chile and Uruguay. The protocol is identical to the PETHEMA-LPA2005, except for the replacement of idarubicin by daunorubicin. In our interim analysis, estimated 2-year overall and disease-free survivals are 80% and 90%, respectively. The 2-year cumulative incidence of relapse was 5.6%. The median follow-up among survivors was 23 months (range: 1 – 56 months). A secondary aim of IC-APL was to establish molecular monitoring for minimal residual disease (MRD) as a standard practice for APL patients in these countries and to use the results obtained to guide therapy. According to the IC-APL protocol, testing for the PML-RARA fusion transcript was to be performed at diagnosis, end of induction (optional), after the third cycle of consolidation, and every 3 months during maintenance. Considering that real-time quantitative polymerase chain reaction (RQ-PCR) provides a number of advantages compared to conventional non-quantitative reverse transcriptase PCR (RT-PCR), we retrospectively compared the results obtained by both techniques. We analyzed 400 bone marrow (BM) samples from 97 patients with de novo APL enrolled in the IC-APL protocol in Brazil. Of the 97 patients, 78 were considered eligible. The mean age was of 35.8 years with 46 males. Among eligible patients, 49 corresponded to bcr1 ; one to bcr2 and 28 to bcr3 subtype of PML breakpoint. To quantify the fusion transcript PML-RARA we used standardized assays developed in the Europe Against Cancer (EAC) program, normalized to the expression of the ABL gene. The results were compared to plasmid standards (Ipsogen, Marseille) and expressed as Normalized Copy Numbers (NCN). Follow-up samples were considered PCR positive when PML-RARA transcripts amplified with Cycle Threshold (Ct) values of ≤40 in at least 2 out of 3 replicates, according to EAC criteria. A total of 71 samples at diagnosis, 50 at the end of induction, 47 after the third consolidation, 202 during maintenance phase and 30 samples after completion of treatment were analyzed. The median NCN of PML-RARA transcripts at diagnosis was 0.5151 and 0.5092 for the bcr1 and bcr3 subtypes, respectively. At the end of induction there was a reduction of about 3 logs (0.0004 for bcr1 and 0.0005 for bcr3). In this phase, six discrepant cases were observed, all presenting positivity by RQ-PCR. None of these cases relapsed and presented consecutive negative results. Considering samples obtained at the end of consolidation, we detected one case of molecular persistence detected by both methods, and two discrepant results, one positive by RT and another by RQ-PCR. Both cases did not relapse. Among samples collected during maintenance and after the end of treatment, two patients (2.5%) relapsed. Both of them were molecular relapses, defined as the detection (in the context of morphological remission) of the PML-RARA transcript by RT-PCR in two consecutive samples collected 15 days apart. RQ-PCR analysis provided much earlier warning of recurring disease, testing positive 5 and 6 months, respectively, before documentation of molecular relapse by conventional RT-PCR assay. Figure 1 show the kinetics of NCN in these two cases. Our results reinforce that the PML-RARA transcript may be detected after induction but this finding was not of prognostic value. However, our study underlines the importance of sequential monitoring to distinguish patients likely to be cured following front-line therapy from those destined to relapse. The RQ-PCR technique was shown to be more sensitive than RT-PCR, providing earlier warning of impending relapse, thereby allowing greater opportunity for successful delivery of pre-emptive therapy. Finally, our results demonstrate that the implementation of the IC-APL allowed the improvement of laboratory standards in parallel to advances in clinical management. [Display omitted] Disclosures:Pasquini:Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bristol Myers Squibb: Speakers Bureau. Pagnano:Novartis: Speakers Bureau; Bristol Myers Squibb: Speakers Bureau.

Improving the Treatment Outcome of Acute Promyelocytic Leukemia in Developing Countries through International Cooperative Network. Report On the International Consortium On Acute Promyelocytic Leukemia Study Group.

Abstract 6▪▪This icon denotes an abstract that is clinically relevant.Acute promyelocytic leukemia (APL) is a curable disease, and contemporary treatment based on the combination of all-trans retinoic acid (ATRA) with anthracyclines results in overall survival (OS) rates of around 90% at five years. Unfortunately, the treatment outcome of patients with APL in developing countries is significantly less. A recent Brazilian study had reported an OS of 53% with a first 5-days mortality of 13.4%. The International Consortium on Acute Promyelocytic Leukemia (IC-APL) is an initiative of the International Members Committee of the ASH and the project aims to reduce this gap through the establishment of international network, which was launched in Brazil, México and Uruguay. All patients with a suspected diagnosis of APL were immediately started on ATRA, while bone marrow samples were shipped to a national central lab where genetic verification of the diagnosis was performed. Results of the immunofluorescence for PML was obtained within hours and upon confirmation of the diagnosis, patients were enrolled in a protocol identical to the PETHEMA-LPA 2005, except for the replacement of idarubicin by daunorubicin. Supportive care aimed at maintaining platelet counts above 30,000/μl and fibrinogen levels above 150 mg/dl. In each country, cases were discussed every other week through internet and whenever needed international experts were involved. As of June 2009, 102 (70 Brazil, 25 Mexico, 7 Uruguay) APL patients were enrolled. The median age was 34 y (range: 9–72y) with 55 males (54%).The median white blood cell counts (WBC) at baseline was 3.6×109 /L(range: 0.2–149.7). The distribution of the relapse risk score at diagnosis according to PETHEMA-GIMEMA criteria was 14 low (14%), 54 intermediate (53%) and 34 high risk(33%) respectively. The incidence of low risk APL appeared lower than the values reported in developed countries. Of 102, 97 patients have toxicity and response data available. Of these 97, 12 (12.3%)experienced at least three symptoms/signs of differentiation syndrome (DS) and 77 (79%) patients achieved a complete remission (CR). Twenty-three deaths occurred and the cause of deaths included 9 hemorrhage, 8 infection, 2 DS . The 7 and 30 day mortality rates were 8% and 19.6%, respectively, and the one- year overall survival was 75% (95%CI:68%–84%). The median follow-up time among survivors was 14 months (range: 1.3–35). Among 77 patients who achieved CR, the 1-year OS and disease-free survival from the date of CR was 95% (95% CI: 89%–100%). Only one patient relapsed. For patients surviving a minimum of 30 days the outcome was similar to that reported by the twin PETHEMA-LPA 2005 protocol in European patients. Prognostic factors for overall survival were examined using log-rank test as well as multivariate Cox models. Factors predicting OS were a high relapse risk score at baseline (1-year OS: 59% for high, 87% for intermediate, 91% for low, p=0.0007) and age. The 1-year OS was 85% for age<25, 83% for 25–40, and 58% for age≥40 (p=0.008 for age≥40 vs<40). In the Cox model, these two prognostic factors remain to be significantly associated with OS [HR=3.77, p=0.004 for high relapse risk score; HR=2.4, p=0.047 for age≥40]. In conclusion, the establishment of the IC-APL network resulted in a decrease of about 40% in early mortality and improvement of the outcome to levels similar to those reported in developed countries. Disclosures:Sanz:Amgen Inc.: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.