1038 Poster Board I-60 Background: Outcome of patients (pts) with AML refractory to initial induction is assumed to be poor but the available data is limited. Furthermore, pts refractory to standard dose cytarabine-based regimens may be salvaged with high dose ara-C (HiDaC, defined as daily ara-C dose ≥ 1 g/m2). Information on the outcome of pts refractory to initial HiDaC - based induction is more limited. Aim To better characterize predictors of poor response to HiDaC-based induction and to evaluate the outcome of pts refractory to such induction regimens. Methods: We identified pts treated with induction regimens containing HiDaC at the University of Texas – M D Anderson Cancer Center who did not achieve a compete remission (CR) after one cycle of induction. We examined their pre-treatment characteristics and compared them with similar pts achieving a CR. We also examined their response to salvage chemotherapy and outcome. Results: Among 1179 pts treated with HiDaC-based induction therapy from 1995 to 2009, 285 were primary refractory to one course of induction. Their median age was 59 (range, 18 - 85). Median pretreatment WBC was 9.0 × 109/L (range, 0.3 – 394 × 109/L). Cytogenetics included-5/-7/complex 101 (35%), diploid 85 (30%), other intermediate 98 (34%), favorable 1 (<1%). 165 (58%) pts had antecedent hematological disorder. Induction regimens used included HiDaC with anthracyclines (n=181, 64%), HiDaC with non-anthracycline chemotherapy (fludarabine, clofarabine, topotecan, and troxacitabine) (n=104, 36%) Pts with primary refractory disease were older (Median age 59 vs. 56; p=000004), more likely to have chromosome 5/7 or complex cytogenetic abnormalities (P=0.0001), more likely to have AHD (p=0.0001), and had a higher presentation WBC (P=0.036), but not a higher incidence of FLT3 mutations (p=0.85) than those achieving CR. Primary refractory disease was not more likely with non-anthracycline containing regimens than those with anthracyclines (p=0.58). Salvage chemotherapy included combination chemotherapy in 111 (39%)(non-ara-C regimen in 40, containing ara-C in 71), single agent chemotherapy in 64 (22%), allogeneic stem cell transplant in 22 (8%) and none in 88 (31%). Forty-three (15%) pts responded to salvage including 35 CR and 8 CRp. 114 (58%) pts were resistant and 35 (18%) died; 5 (3%) were lost to follow-up. With a median follow-up of 115 weeks (range 8 – 347 weeks) in pts responding to salvage, 21 pts (7%) were alive and in CR, for at least 6 months including 14 who underwent an allogeneic stem cell transplant (median overall survival for these 21 pts, 30 months; range, 13 to 87 months). Conclusions: Outcome of pts with disease refractory to HiDaC-based induction is poor. Alternative strategies are needed in these pts who are likely to be resistant to standard chemotherapy. Disclosures: No relevant conflicts of interest to declare.
Background The combination of vorinostat, idarubicin and cytarabine (IA+vorinostat) is associated with high response rate in patients with newly diagnosed acute myelogenous leukemia (AML) or higher-risk myelodysplastic syndromes (MDS) (JCO 2012;30:2204). In that study, presence of FLT3-ITD was associated with 100% overall response rate (ORR) in 11 patients. To confirm the efficacy of this combination, we extended the phase II study to treat 2 additional cohorts: one for patients with newly diagnosed (untreated cohort) and the other with relapsed and refractory (R/R cohort) AML or higher-risk MDS with FLT3 alteration (both ITD and D835 mutation). Methods Patients with the above diagnosis, ages 15 to 65 years, with appropriate organ function (measured cardiac ejection fraction ≥ 50%, serum creatinine ≤ 2 mg/dl, total bilirubin ≤ 2 mg/dl, and GPT/GOT ≤ 2.5 x upper limit of normal) whose eastern cooperative group (ECOG) defined performance status ≤ 2 were eligible for the study. Study treatment comprised of vorinostat 500 mg orally three times a day (days 1 to 3), idarubicin 12 mg/m2 intravenously (IV) daily x 3 days (days 4 to 6), and cytarabine 1.5 g/m2 IV as a continuous infusion daily x 3 - 4 days (days 4 to 7). Patients in remission could be treated with five cycles of consolidation therapy with lower dose combination and up to 12 months of maintenance therapy with single-agent vorinostat. Result Untreated cohort included 26 patients, whereas 13 patients were treated in R/R cohort (total 39 patients). Thirty six patients had de novo AML, 1 had de novo MDS and 2 had therapy-related AML. For the R/R patients, the median number of prior therapies was 3 (range: 1-6). The median age of the entire study group was 49 (range: 19-64) and 17 (44%) were male. Among the patients whose cytogenetic result were available, 20 (51%) patients had normal and 15 (39%) had abnormal karyotype. By Medical Research Council (MRC) criteria, 30 (77%) patients had intermediate risk and 9 (23%) had poor risk karyotype. Thirty three (85%) patients had FLT3-ITD only, 4 (10%) had both FLT3-ITD and D835 mutation, and 2 (5%) had D835 mutation only. Seventeen (44%) patients had NPM1 mutation. In untreated cohort (N = 26), CR and CRp were documented in 21 (80%) and 2 (8%) patients, respectively (ORR = 88%). In R/R cohort (N = 13), overall response (OR) was observed in 4 (30%) patients (CR in 2 [15%] and CRp in 2[15%]). Of those 4 patients who had OR in R/R cohort, 2 patients were refractory to other high-dose cytarabine-based regimen. The median duration of CR or CRp was 9.2 months (range: 0.1-48.4) in untreated cohort and was 2.9 months (range: 1.6-4.7) in R/R cohort. Twelve (46%) patients in the untreated cohort were bridged to stem cell transplant (SCT) while they were in 1st CR. None of the patients in R/R cohort were bridged to SCT. No difference in response was observed in 1) younger (Age < 60) vs. older patients, 2) normal vs. abnormal karyotype, 3) intermediate vs. poor risk cytogenetics by MRC criteria, 4) presence of RAS mutation, 5) presence of NPM1 mutation, or 6) de novo vs. therapy-related disease. The median overall survival (OS) was 21.7 months (95% CI: 8.1-35.3) in the untreated cohort and was 4.9 months (95% CI: 0.1-10.4) in the R/R cohort. Early treatment related mortality (defined by the death within 4 weeks of the induction) was documented in 1 (4%) patient in the untreated cohort and 2 (15%) patients in the R/R cohort. Toxicity profiles were similar to that reported in the original phase II study (JCO 2012;30:2204). Discussion Vorinostat in combination with IA provides high response rate and durable remission in previously untreateed AML or higher risk MDS patients with FLT3 alteration but is less effective in patients with R/R disease. Phase III randomized study of IA+/- vorinostat in previously untreated AML patients is ongoing (SWOG S1203). Disclosures: Off Label Use: vorinostat in MDS and AML. Cortes:Ambit: Research Funding; Astellas: Research Funding; Argo: Research Funding; Novartis: Research Funding.
1550 Background: Clofarabine is a second generation nucleoside analogue with activity in adults with AML. A recent randomized phase III study in AML relapse showed higher response rates and better event-free survival with the combination of clofarabine and cytarabine (CA) compared to cytarabine alone. We have also reported the feasibility and safety of the addition of idarubicin to CA (CIA) in a previous phase I and II study. To explore this combination further, we conducted a phase II study of CIA in pts</= 60 years with previously untreated AML. Patients and Methods: Patients (Pts) were eligible if they were </=60 yrs of age with newly diagnosed AML. Pts were excluded for ECOG PS > 2, cardiac ejection fraction < 45%, or active and uncontrolled infection. For the first 30 pts, induction therapy consisted of Clofarabine 22.5 mg/m2 iv daily (days 1–5), Idarubicin 6 mg/m2 daily (days 1–3), and Cytarabine 0.75 g/m2 daily (days 1–5). From pt 31 onward, induction doses were amended to Clofarabine 20 mg/m2 × 5, Idarubicin 10 mg/m2 × 3, and Cytarabine 1 g/m2 × 5. Pts who have not achieved a complete remission following the induction could receive one re-induction course. Pts in CR or CRp continued with up to 6 consolidation cycles with Clofarabine 22.5 mg/m2 × 3, Idarubicin 6 mg/m2 (days 1–2), and Cytarabine 0.75 g/m2 × 3, subsequently amended to Clofarabine 15 mg/m2 × 3, Idarubicin 8 mg/m2 × 2, and Cytarabine 0.75 g/m2 × 3. Supportive care was standard. Pts ≥ 50 yrs were admitted to a laminar air flow room for the duration of the induction. Results: From April 2010 until August 2011, 51 pts have been accrued with a median age of 49 yrs (range 19–59): 33 pts (65%) with de novo AML and 18 pts (35%) with secondary AML (18 related to MDS, 7 related to therapy). Three pts (5%) had a PS of 2. Median WBC at diagnosis was 3.4 × 109/L (0.6-92.3). Thirty-three (65%) pts had abnormal cytogenetics (21/33[64%] poor risk and 5/33 [15%] intermediate risk). Molecular profile: 6 pts (11%) had FLT3/ITD, 3 pts (6%) CEBPA, and 8 pts (16%) NPM1 mutations. Thirty-five pts (69%) achieved CR and 1 (2%) CRp for an overall response rate (ORR) of 71%. 61% pts (31/51) achieved CR following one induction cycle. 18% (9/51) pts required a re-induction and 44% (4/9) of them responded after the re-induction. Responding pts received a median of 2 courses (1–8) courses. With a median follow-up of 23 weeks (3–36+) median remission duration has not been reached with a 1-yr remission probability of 85%. Ten pts (19%) died on study including 2 (4%) who died < 28 days from treatment start (one from septic shock and multi-organ failure, and one from Steven Johnson syndrome). Median overall survival (OS) for responding pts has not been reached (2–36 weeks). One-yr survival probability is 65%. Sixteen pts (31%) proceeded with an allogenic stem cell transplant in CR1. Most toxicities were </= grade 2 and included rash (41 %), nausea (29%), diarrhea (23%), elevated transaminases (21%), and elevated bilirubin (17%). Toxicities > grade 2 included elevated bilirubin (4%), hypokalemia (4%), cellulitis (4%) and seizure (1%). Myelosuppression was ubiquitous but prolonged myelosuppression > 42 days was infrequent. 76 % (39/51) pts had neutropenic fever. Conclusion: Clofarabine, Idarubicin and Cytarabine achieve a response rate of 71% in patients </=60 yrs with previously untreated AML. Induction mortality was low and the toxicity profile was expected and manageable. Longer follow up and comparisons with standard induction therapy will be needed to further assess the role of this combination in AML therapy. Disclosures: Off Label Use: Clofarabine, use of Clofarabine in AML. Ravandi:Genzyme: Research Funding. Kantarjian:Genzyme: Research Funding. Faderl:Genzyme: Membership on an entity's Board of Directors or advisory committees, Research Funding.
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