Abstract: The introduction of all-trans-retinoic acid (ATRA) has significantly improved outcomes for acute promyelocytic leukemia (APL), although a subset of patients still suffer relapse. The purpose of this study was to evaluate the role of maintenance therapy with the synthetic retinoid tamibarotene in APL. Patients and Methods Patients with newly diagnosed APL in molecular remission at the end of consolidation therapy were randomly assigned to receive ATRA or tamibarotene, both orally, for 14 days every 3 months for up to 2 years. Results A total of 347 patients were enrolled. Of the 344 eligible patients, 319 (93%) achieved complete remission. After completing three courses of consolidation therapy, 269 patients underwent maintenance random assignment. The relapse-free survival (RFS) rate at 4 years was 84% for the ATRA arm and 91% for the tamibarotene arm (hazard ratio [HR], 0.54; 95% CI, 0.26 to 1.13). When the analysis was restricted to 52 high-risk patients with an initial WBC count ≥ 10.0 × 10 9 /L, the intergroup difference was statistically significant, with 4-year RFS rates of 58% for the ATRA arm and 87% for the tamibarotene arm (HR, 0.26; 95% CI, 0.07 to 0.95). For patients with non–high-risk disease, the HR was 0.82 (95% CI, 0.32 to 2.01). The test for interaction between treatment effects and these subgroups resulted in P = .075. Both treatments were generally well tolerated. Conclusion In this trial, no difference was detected between ATRA and tamibarotene for maintenance therapy. In an exploratory analysis, there was a suggestion of improved efficacy of tamibarotene in high-risk patients, but this requires further study.

Abstract: Imatinib mesylate (IM) given orally at a daily dose of 400 mg was the standard of care as initial therapy for patients with chronic myeloid leukemia (CML) in the chronic phase (CML-CP), before 2ndTKI era. Treatment guidelines by European Leukemia Net (ENL) propose dose escalation based on clinical assessments of disease response in 2006. Preclinical data and results of single-arm studies raised the suggestion that better results could be achieved with a higher dose. However, randomized study to compare high-dose IM (800 mg) with the standard dose (400 mg) as front-line in all CML high-risk patients did not support the extensive use of high-dose IM. To improve the results of CML therapy, another alternative strategy is a dose-escalation based on more aggressive clinical assessments of disease response in comparison with the standard ELN proposed. In 2007, we conducted a prospective randomized study to compare different dose escalation programs; the standard-dose escalation program proposed by ENL (Group A) and the aggressive dose escalation program (Group B) among newly diagnosed patients with CML-CP. The aggressive dose escalation program consisted of the following interventions. If the patients do not obtained a complete cytogenetic response at 3 months or do not reach a major molecular response (MR3, IS=0.1%), IM is increased from standard dose of 400mg daily to 600 mg daily. The primary endpoint is the rate of major molecular response at 12 months, which is a surrogate for long-term progression-free survival (PFS). It is also a surrogate for complete molecular response, which is pointed out recently to be the condition for treatment free survival. Total 248 patients entered to this study between June 16 2007 and June 15, 2011. Median age was 49 years old (range 15-69); 86 were female and 162 were male. Sokal score index was high-risk in 46 patients, intermediate-risk in 77 and low-risk in the remaining. White blood cell count at diagnosis was 43X10^9/L in median (10-881 in range). There was no significant difference between Group A (N=126) and Group B (N=127) according to these factors. Overall survival was 100%, 98% and 98% at 1, 2 and 3 years after treatment, respectively. Three patients developed blast crisis during 3 years (day 177, 272, 481) and all received hematopoietic stem cell transplantation (HSCT). Two other patients who had no cytogenetic response also received HSCT. Eleven patients (4.5%, Group A, N=8, Group B, N=3) failed to achieve complete hematological remission. The overall complete cytogenetic response (CCR) rate at 6 months after the treatment was better in Group B (89%) than in Group A (79%) with borderline significance (p=0.05, Fisher's exact test). However, the overall CCR rate at 12 months was 92% in both groups. At 12 months, MR3 was achieved in 61% and 64% of patients in Group A and Group B, respectively (p=0.69). Also, at 24 months, MR3 was achieved in 91% and 87% of patients in Group A and Group B, respectively. At 3 months, plans called for 8 and 45 patients to increase the dose of IM to 600 mg in Group A and B, respectively; however, only 4 and 27 patients followed the protocol. At 6 months, 10 and 55 patients were to increase the dose of IM to 600 mg in Group A and B, respectively; however, only 2 and 24 patients followed this protocol. The main reason was intolerance of IM. Among the patients who were to increase the dose at 3 and 6 months, 53% of those who could do according to the protocol achieved MR3 at 12 months, while only 16% of patients failed to increase (p=0.08). Eighty patients experienced drug discontinuation during 1 year. The incidence of discontinuation was 37% in Group B, whereas it was 29% in Group B (p=0.18). A substantial part of patients withdrew from this study; however, there was no difference between Groups (A 20%, B 21%). This is the first randomized study to compare two different dose escalation programs. The aggressive dose escalation program showed a better early cytogenetic response than the standard-dose escalation program, but, failed to evidence a better molecular response in a later period. Higher efficacy of high dose IM might be cancelled by the more frequently discontinuation of IM in this group. This study concluded that aggressive dose escalation is not recommended and careful management of drug dose according to patients' condition (residual leukemia, adverse effect, emotion) might be the best way for better outcome, which is applicable to new generation TKIs. Disclosures Miyamura: Nippon Shinyaku CO, LT: Honoraria; Pfizer Inc: Honoraria; Novartis Pharmaceutical: Honoraria; Alexion Pharmaceutical Inc: Honoraria. Usui:Bristol-Myers Squibb: Consultancy, Honoraria, Speakers Bureau; Pfizer: Consultancy, Honoraria, Speakers Bureau; Novartis: Research Funding. Nakaseko:BMS: Honoraria, Research Funding; PFIZER: Honoraria, Research Funding; NOVARTIS: Honoraria. Fujita:Chugai Pharmaceutical Co.,LTD: Honoraria. Okumura:Novartis Pharma: Honoraria. Hatta:Novartis Pharma: Honoraria. Naoe:Astellas Pharma Inc.: Research Funding; Kyowa-Hakko Kirin Co.,Ltd.: Honoraria, Patents & Royalties, Research Funding; Celgene K.K.: Honoraria, Research Funding; Amgen Astellas BioPharma K.K.: Honoraria; Chugai Pharmaceutical Co.,LTD.: Honoraria, Patents & Royalties; TOYAMA CHEMICAL CO.,LTD.: Research Funding; Otsuka Pharmaceutical Co.,Ltd.: Honoraria, Research Funding; CMIC Co., Ltd.: Research Funding; Fujifilm Corporation: Honoraria, Patents & Royalties, Research Funding; Sumitomo Dainippon Pharma Co.,Ltd.: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria; Nippon Boehringer Ingelheim Co., Ltd.: Honoraria, Research Funding; Pfizer Inc.: Research Funding.

Abstract: Abstract 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.

Abstract: Abstract 4266 Introduction Imatinib, which is the most successful molecularly targeting drug, is the first-line agent for the treatment of chronic myeloid leukemia patients (CML) in chronic phase (CP). However, some patients show poor response against imatinib therapy, resulting in the progression to blastic phase. To date, several reports showed that imatinib trough plasma concentration (Cmin) was associated with the clinical response in CML patients, while it remains unclear whether Cmin reflects the actual inhibitory effect on the BCR-ABL kinase activity. In human plasma, imatinib binds to several plasma proteins, such as albumin (ALB) and alpha1-acid glycoprotein (AGP), and the protein-binding-imatinib lacks the kinase inhibitory activity. Especially, AGP is a major imatinib-binding protein, and the high plasma AGP concentration reportedly reduces the clinical efficacy of imatinib. These results indicate that the free-imatinib concentration is a more reliable surrogate marker for predicting the clinical efficacy than the total imatinib concentration. However, since routine measurements of the free-imatinib concentration is difficult, the inhibitory activity of the patient's plasma (PIA) against the BCR-ABL kinase is proposed to be a direct marker reflecting the actual inhibitory effects of the free-imatinib. In this study, we analyzed the association between Cmin of total imatinib and the clinical response in CML-CP patients in considering the AGP concentration. Furthermore, we evaluate the usefulness of PIA for predicting the clinical response in the CML patients treated with imatinib. Methods We measured Cmin of the total imatinib and AGP and ALB concentrations at the different two points in CML-CP patients who were treated with imatinib alone. The PIA was quantified by determining the de-phosphorylation levels of BCR-ABL and STAT5 in BCR-ABL-expressing Ba/F3 cells after the treatment with patients' plasma. We evaluated the association of these parameters with clinical response. Informed consent was obtained from all patients to use their samples for this study. This study was approved by the ethical committee of Nagoya university school of medicine. Results The study population included 65 CML-CP patients. The mean Cmin of imatinib was 1070 ± 362 ng/ml. Clinical response was evaluated by the achievement of the complete cytogenetic response (CCR) and major molecular response (MMR) at 12 months after the start of imatinib therapy. The CCR and MMR were achieved in 63 (96.9%) and 40 (61.5%) patients, respectively. The mean Cmin of the patients who achieved MMR was significantly higher than that of those who did not (1167 ± 386 ng/ml vs. 913 ± 257ng/ml, P=0.012). The differences of Cmin between the two different points (median interval 28 ± 20 days) in the same patient were not so little (median 123 ± 198 ng/ml, range 12 to 923 ng/ml), but were not associated with clinical outcomes. The PIA was statistically correlated with the Cmin (P=0.018). Although serum AGP level was within normal range (72.8 ± 13.9 mg/dl, range 44 to 106 mg/dl) in most patients, it was notable that the serum AGP level correlated with Cmin of imatinib and clinical outcomes. The Cmin of patients with high AGP level was significantly higher than that of low AGP level (1237 ± 379ng/ml vs. 907 ± 260ng/ml, P=0.0003) and the MMR rate was significantly higher in patients with high AGP level (78%) than in those with low AGP level (45%, P=0.007). Conclusions We demonstrate that the Cmin of imatinib predicts clinical response and reflects the actual kinase inhibitory effects in CML patients treated with imatinib. However, the Cmin is not necessarily stable during the treatment in a part of patients, suggesting that it is recommended to examine Cmin at more than two different points for evaluating its suitability. The serum AGP and ALB levels did not affect the relationship between Cmin and PIA. However, since the serum AGP level was correlated with Cmin and clinical response, the AGP level might influence the kinase inhibitory activity in the patients whose Cmin of imatinib were low. Disclosures: Kiyoi: Novartis Pharma : Research Funding; Kyowa Hakko Kirin Co., Ltd. : Consultancy. Naoe:Kyowa Hakko Kirin Co., Ltd. : Research Funding; Chugai Pharmaceutical Co.,Ltd.: Research Funding; Wyeth K.K.: Research Funding.

Abstract: One of the most critical issues to be solved in regard to cancer chemotherapy is the establishment of ways to predict the efficacy of anti‐cancer drugs for individual patients. To develop a prediction system based on expression of specific genes, we analyzed expression profiles of mononuclear cells from 18 chronic myeloid leukemia (CML) patients who were treated with the tyrosine kinase inhibitor STI571. cDNA microarrays representing 23 040 genes identified 79 genes that were expressed differentially between responders and non‐responders to STI571. On the basis of the expression patterns of 15 or 30 of these genes among the patients, we developed a “Prediction Score” system that could clearly separate the responder group from the non‐responder group. Verification of this system using four additional (“test”) cases succeeded in predicting the response of each of those four patients to the drug. These results provide the first evidence that gene‐expression profiles can predict sensitivity of CML cells to STI571, and may eventually lead to the achievement of “personalized therapy” for this disease.

Abstract: In 2007, we conducted a prospective randomized study to compare an aggressive dose escalation (group B, n = 123) with the standard dose escalation proposed by European LeukemiaNet (group A, n = 122). In group B, if patients did not achieve a complete cytogenetic response (CCyR) at 3 months or did not achieve a major molecular response (MR3) at 6 months, imatinib was increased to 600 mg. At 6 months CCyR was achieved in 69.4% and 78.7% of patients in groups A and B, respectively. The rate of MR3 at 12 months and 24 months were similar in group A (52.1% and 70.0%) and group B (58.7% and 68.3%). The cumulative incidence of withdrawal by failure without accelerated/blast phase was higher in group A than in group B (9.2% vs 2.5% at 24 months). At 3 and 6 months, the protocol called for the imatinib dose to increase to 600 mg in 90 patients (74.4%) in group B. Among the 42 patients who received increased dose according to the protocol, 25 (60.0%) achieved MR3 at 12 months, whereas only 14 (35.0%) of 40 patients who did not receive an increased dose achieved MR3 (P & lt; .05). The number of patients who withdrew from this study was similar (group A, 20%; group B, 21%). The early aggressive dose escalation failed to produce a better molecular response at 12 months. However, for patients who tolerate imatinib well, but show inadequate response at an early time point, aggressive dose escalation may contribute to achieving a better outcome. This study was registered at http://www.umin.ac.jp/ctr/ as #R000000965.

Abstract: Background: A combination of all-trans retinoic acid (ATRA) and chemotherapy (CT) has dramatically improved the prognosis of acute promyelocytic leukemia (APL). Nevertheless, considerable number of patients are either refractory to the treatment or relapse after an initial complete remission (CR). Although prognostic factors for APL have been studied, the influence of chromosomal variations in addition to t(15;17) remains controversial. One of the reasons is due to the numbers of cases studied were relatively small (47 to 513 cases). Here, we analyzed clinical features and outcomes of 775 APL caseswith or without additional chromosome abnormalities (ACAs) who were treated with ATRA and CT in the JALSG-APL studies including a large number of cases analyzed for karyotype. Methods: 1,024 cases aged between 15 and 70 yrs with newly diagnosed APL were enrolled in the JALSG APL92, 95, 97 and 204 studies and 775 patients were assessable for karyopypes. All protocols included induction therapy with ATRA and CT, following several courses of post-remission chemotherapy including anthracyclines. Arsenic trioxide (ATO) was not included. Clinical and biological characteristics such as age, gender, initial leukocyte count, platelet count, number of APL cells, DIC score, lack of Auer-rod and incidence of variant type were analyzed in relation to chromosomal abnormalities in 766 cases. CR rate, relapse rate (RR), overall survival (OS), event-free survival (EFS), and disease-free survival (DFS) were assessed and compared between patients with or without ACAs. Each variation of ACAs was also analyzed with clinical and biological features. This work was supported in part by the National Cancer Center Research and Development Fund (26-A-24), Grants-in-Aid from the Cancer Research from the Japanese Ministry of Health, Labor and Welfare (#23-004 and #25100501). These studies were approved by our IRB. Results: ACAswere noted in 235 patients (30%). Sanz score and the initial leukocyte count were significantly lower in patients with ACAs (p=0.027 and p=0.027, respectively). No other clinical or biological differences were found between patients with and without ACAs. The subgroups of ACAs were shown in Figure 1. Trisomy 8 was found in 76 cases (32%). Other ACAs were found involving chromosome 15 in 37 cases (16%), both chromosomes 15 and 17 in 31 cases (13%), chromosome 7 in 19 cases (8%), chromosome 9 in 12 cases (5%), chromosome 6 in 8 cases (3%), chromosome 21 in 7 cases (3%) and alternative ACAs in 43 cases (18%). A low initial leukocyte count ( 〈 3,000/µl) was significantly associated with an abnormality of chromosome 15 (p=0.039) and a high initial leukocyte count (≥10,000/µl) was associated with other unspecified chromosomal abnormalities (p=0.010). In all cases, CR rate, OS, EFS and DFS were not different between patients with and without ACA (p=0.341, p=0.694, p=0.414, p=0.852, respectively). However, in elderly patients (≥50 yrs) with ACAs, OS, EFS and DFS were significantly lower compared to younger patients ( 〈 50 yrs) (p=0.019, p=0,023 and p=0.030, respectively) (Figure 2). No such age related difference was observed for patients without ACAs (OS, p=0.068; EFS p=0.485; DFS, p=0.672). In each risk group divided by initial leukocyte count, clinical outcomes were not different between patients with and without ACAs. In patients without ACAs, OS, EFS and DFS of patients assigned to no maintenance or retinoid maintenance were significantly better than in those allocated to the maintenance CT (p 〈 0.001, for all). (Figure 3) The significance was not observed in patients with ACAs except DFS (OS, p=0.161; EFS p=0.293; DFS p=0.043). Conclusions: The present study is the largest to date to focus on the influence of ACAs on clinical outcomes of patients with APL treated with ATRA and CT. The analysis revealed exact variation and frequency of ACAs. We found that patients with ACAs were associated with the lower initial leukocyte count and the lower survival outcomes in elderly patents, suggesting a possible link to age and post-remission chemotherapy. Some promising agents, such as ATO, tamibarotene and gemtuzumab ozogamicin might change the prognostic factors, including ACAs. Careful chromosomal analyses, especially ACAs related to chromosome 15 and/or 17, need to be analyzed by molecular methods and performed in future prospective studies with alarge number of cases. Figure 1 Figure 1. Figure 2 Figure 2. Figure 3 Figure 3. Disclosures Kiyoi: Bristol-Myers Squibb: Research Funding; Chugai Pharmaceutical Co. LTD: Research Funding; Kyowa Hakko Kirin Co. LTD.: Research Funding; Dainippon Sumitomo Pharma: Research Funding; Zenyaku Kogyo: Research Funding; FUJIFILM Corporation: Research Funding. Kobayashi:Ohtsuka: Research Funding; Behringer: Research Funding; Simic: Research Funding. Asou:Chugai Pharmaceutical Co., Ltd.: Research Funding. Miyazaki:Nippon-Shinyaku: Honoraria.