Generation Nucleoside Analogue Research Articles

Abstract IA20: PET imaging of the immune system using new nucleoside analog probes

Abstract Similar to other major metabolic networks, nucleotide metabolism consists of redundant and convergent biosynthetic pathways. Thus, nucleotides can be produced both de novo, from glucose and amino acids, and by salvage pathways, via scavenging and re-utilization of preformed nucleosides and nucleobases. The differential utilization of de novo and salvage nucleotide biosynthetic pathways in normal and malignant is poorly understood. We are studying this process in lymphocytes and cancer cells using newly developed mass spectrometry and positron emission tomography (PET) approaches. Deoxycytidine kinase (dCK), a rate-limiting enzyme in the cytosolic deoxyribonucleoside salvage pathway, is significantly upregulated following T cell activation and therefore represents a promising PET imaging target. PET probes for dCK have been previously developed by our group and shown to be effective in mice but their specificity and sensitivity in humans remained suboptimal. Recently we have identified [18F]CFA (2-chloro-2′-deoxy-2′-[18F]fluoro-9-β-D-arabinofuranosyl-adenine) as a suitable third generation nucleoside analog probe for clinical dCK PET imaging. First-in-human [18F]CFA PET/CT studies showed probe accumulation in tissues with high dCK expression: e.g., hematopoietic bone marrow and secondary lymphoid organs. The potential use of [18F]CFA PET for imaging systemic immune activation induced by various cancer immunotherapies will be discussed. Citation Format: Caius G. Radu. PET imaging of the immune system using new nucleoside analog probes. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr IA20.

Clofarabine Plus Low-Dose Cytarabine for the Treatment of Patients with Higher-Risk Myelodysplastic Syndrome (MDS) Who Have Been Relapsing after, or Are Refractory to, Hypomethylating Agent (HMA) Therapy

▪Background: HMA therapy is standard of care for patients with MDS. Outcome post HMA failure is poor with a median survival of 4-6 months. Clofarabine is a second generation nucleoside analog with single agent activity in MDS. The objective of this phase II trial is to evaluate the safety and activity of the combination of clofarabine and low dose cytarabine in the treatment of patients with high risk MDS who failed prior HMA therapy.Methods: Eligible patients were adults older than 18 years with MDS intermediate-1 and higher by the IPSS, who have had no response, progressed, or relapsed following at least 4 cycles of therapy with either azacitidine and/or decitabine. Patients were required to have an Eastern Cooperative Oncology Group performance status of </=2 at the time of study entry. Responses were defined according to International Working Group 2006 criteria. Induction therapy consisted of clofarabine 10-15 mg/m2 IV daily X 5 days (days 1-5) and cytarabine 20 mg SC twice daily X 7 days (days 1-7). Patients could receive up to 3 induction cycles as long as they tolerated the therapy and had stable disease. Responding patients proceeded with consolidation therapy with clofarabine 10-15 mg/m2IV daily X 3 days (days 1-3) and cytarabine 20 mg SC twice daily X 5 days (days 1-5) for a maximum of 12 cycles. Cycles were repeated every 4 to 8 weeks depending on hematopoietic recovery and resolution of toxicities.Results: From January 2012 to August 2015, 80 eligible patients were enrolled in this prospective study (NCT01444742) and received a median of 2 cycles (range, 1-12) (Table 1). The overall response rate (ORR) was 46% (16 [20%] achieved complete remission (CR), 17 [21%] marrow CR, 1 [1%] partial response (PR), 3 [4%] hematological improvement (HI)) with a median response duration of 7 months. The median time to response was 42 days (range, 9-191). By multivariate analysis, complex karyotype was the only independent factor predicting for response (hazard ratio [HR] 0.13; 95% confidence interval [CI]: 0.03- 0.62; p=0.01). Of the 37 patients with diploid karyotype, the overall response was 68% (7 [19%] achieved CR, 15 [41%] marrow CR, 1 [3%] PR, 3 [4%] HI). Nine of the responding patients received subsequent allogeneic stem cell transplant (ASCT). With a median follow-up of 24 months (range: 1-51 months), the median event-free survival (EFS) and overall survival (OS) times were 5 months (95% CI: 2.7-6.3) and 11 months (95% CI: 6.5-14.9), respectively (Figure 1). The median OS for responding and non-responding patients was 24 months (95% CI: 11.7-35.6) and 5 months (95% CI: 2.8-6.2), respectively (p<0.001). There was no difference in OS whether patients were censored or not at the time of ASCT (p=0.463). At last follow-up, 22 patients (28%) remained alive: 1 is receiving low-dose clofarabine and cytarabine, 5 are alive in response after ASCT, 9 are receiving salvage therapy, 1 went to hospice, and 6 were lost to follow-up. By multivariate analyses, complex karyotype, platelet count less than 30 x 109/L, and poor performance status were independently associated with poor survival. In addition, the response to the combination of low-dose clofarabine and cytarabine was independently associated with better OS (HR 0.17; 95% CI 0.09-0.36; p<0.001). Grade ≥ 3 therapy-related toxicity included infections (34%), increased liver functional tests (8%), acute renal failure (3%), skin rash (3%), syncope (1%), and rectal bleeding (1%). Twenty-two (28%) patients had clofarabine dose reduction after a median of 2 courses. After 47 patients were enrolled and several patients experienced infections during induction, the protocol was amended to reduce the dose of clofarabine to 10 mg/m2 per day for 5 and 3 days during the induction and consolidation phases, respectively. There was no difference in responses before and after the modification to the protocol’s dosing schedule (p=0.314).Conclusion: The combination of low-dose clofarabine and cytarabine in patients with higher-risk MDS after HMA failure resulted in an ORR of 46% and median OS of 11 months and may be particularly effective in patients with diploid karyotype. Our results also indicate that the combination of low-dose clofarabine and cytarabine may be useful as a bridge to ASCT in eligible patients. [Display omitted] [Display omitted] DisclosuresJabbour:ARIAD: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Research Funding; BMS: Consultancy. Cortes:ARIAD: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Teva: Research Funding. Jain:Abbvie: Research Funding; Infinity: Research Funding; Servier: Consultancy, Honoraria; Incyte: Research Funding; Genentech: Research Funding; Pharmacyclics: Consultancy, Honoraria, Research Funding; ADC Therapeutics: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Research Funding; Celgene: Research Funding; Seattle Genetics: Research Funding; Novimmune: Consultancy, Honoraria; BMS: Research Funding. DiNardo:Agios: Other: advisory board, Research Funding; Daiichi Sankyo: Other: advisory board, Research Funding; Novartis: Other: advisory board, Research Funding; Abbvie: Research Funding; Celgene: Research Funding. Konopleva:Cellectis: Research Funding; Calithera: Research Funding.

Use of Clofarabine in Pediatric Multisystem Langerhans Cell Hystiocytosis

Langerhans cell hystiocytosis has been defined as an inflammatory and/or neoplasm of the hematopoietic system, mainly of myeloid precursors. There is recent evidence of mutations in the BRAFF V600 progenitor cells, which underline its neoplastic nature -myeloprolipherative condition.The diagnosis of LCH relies on a positive biopsy identifying characteristic LCH cells by morphology and immunohystochemistry (CD1a and Langherin). Genetic tests have been added to the diagnostic armamentarium, with prognostic value.Children younger than 2 years, and with risk organ involvement, have an unpredictable, often bad prognosis.There is no current international consensus on LCH treatment, and guidelines are based on the best currently known treatment approaches.Case #1:4 year old girl with MS-LCH with hematologic, bone and lung involvement. She presented early at 18 months of age with pancytopenia, became transfusion dependant of red blood cells and occasional platelets. She was started on LCH-III after a lymph node biopsy showed extramedullary hemopoiesis and positive for LCH (Langherin, Cd1a). She received 12 weeks of initial therapy with vinblastine and prednisolone, with no improvement. Disease progressed with additional bilateral pleural effusion and fever. She was given Clofarabine 25mg/m2/d x5 during 2 courses, with improvement of counts and symptoms. A PET FDG scan was pending to assess disease status.Case #2:18 month old girl with systemic manifestations of MS-LCH since age 3 months, with fever, splenomegaly and anemia. Multiple cranial lesions were found, and skull biopsy at age 13 months was positive for LCH (langherin, Cd1a). BRAFF V600 mutation by PCR of biopsy was negative. cerebral MRI was normal. She was started on LCH-III (vinlastine plus steroids) during 6 weeks. Due to disease progression, worsening splenomegaly, anemia, fever, she was given clofarabine 25mg/m2/d x5. Fever disappeared post 1st course of treatment. Rest of manifestations were gone after 2nd cycle. Treatment was administered as inpatient, with no significant side effects.Clofarabine is a second generation nucleoside analog with activity in refractory AML. It has been used with success as salvage therapy in LCH patients.There is growing optimism with the use of nucleoside analogs as effective treatment of LCH, with dose-dependent effects on therapeutic efficacy, as well as toxicity. DisclosuresOff Label Use: Clofarabine. Second generation nucleoside analog.

Longer Follow-Up Of The Combination Of Clofarabine, Idarubicin, and Cytarabine (CIA) As Frontline Therapy For Patients Younger Than 61 Years With Newly Diagnosed Acute Myeloid Leukemia (AML)

Abstract Background Clofarabine is a second generation nucleoside analogue with activity in adults with AML. In a phase II trial of clofarabine in combination with idarubicin and cytarabine in newly diagnosed patients (pts) with acute myeloid leukemia (AML) &lt;/= 60 years old, the overall response rate (ORR) was 79%. The combination was well tolerated with low induction mortality. Compared to historical pts who were treated with idarubicin and cyarabine (IA), the overall survival (OS) and event-free survival (EFS) were significantly longer for CIA treated pts and mainly for pts &lt;/= 40 years old. Aim To report a longer follow up of this study. Patients and Methods Eligible were adults between 18-60 years old with newly diagnosed AML with adequate renal (creatinine &lt;/= 1.0 mg/dL) and hepatic (bilirubin &lt;/= 1.5 x upper limit of normal, [SGPT and/or SGOT] &lt;/= 2.5 x ULN) functions. Ptswere excluded for ECOG PS &gt; 2, cardiac ejection fraction &lt; 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 x 5, Idarubicin 10 mg/m2 x 3, and Cytarabine 1 g/m2 x 5. Pts who did not achieve a complete remission (CR) following induction could receive one re-induction course. Pts in CR/CRp continued with up to 6 consolidation cycles with Clofarabine 22.5 mg/m2 x 3, Idarubicin 6 mg/m2 X 2, and Cytarabine 0.75 g/m2 x 3, subsequently amended to Clofarabine 15 mg/m2 x 3, Idarubicin 8 mg/m2 x 2, and Cytarabine 0.75 g/m2x 3. Results From April 2010 until February 2012, 57 pts were evaluable. With median follow up of 21.5 months (1.5-33.4), the median OS was 27.4 months, median relapse-free survival was not reached, and median EFS was 11.5 months. Patients &lt;/= 40 years who received CIA had a better OS (HR 0.43, CI 0.24-0.75, P = 0.007), and better EFS (HR 0.43, CI 0.24-0.75, P = 0.007) compared to pts &gt; 40 years. Compared to a historical cohort of pts treated with IA, CIA continued to show superior OS (HR 0.8, CI 0.51-1.27, P = 0.043). In multivariate analysis, CIA retained its prognostic value on OS even when transplant was added as time dependent covariate (HR 0.84, CI 0.53-1.33, P = 0.04). Pts &lt;/= 40 years had superior OS (HR 0.15, CI 0.03-0.65, P= 0.039) when they were treated with CIA compared to IA. Conclusion A longer follow up of the CIA combination in newly diagnosed pts with AML &lt;/= 60 continues to show OS benefit compared to IA alone. Patients &lt;/=40 years continue to benefit the most from this combination regardless of transplant. A randomized trial to compare this combination to standard therapy in AML is needed to further investigate the role of this combination in AML. Disclosures: Off Label Use: Clofarabine use in AML. Kantarjian:Sanofi-Aventis: Research Funding. Ravandi:Sanofi-Aventis: Research Funding. Faderl:Sanofi-Aventis: Membership on an entity’s Board of Directors or advisory committees, Research Funding.

Clofarabine Plus Low-Dose Cytarabine For The Treatment Of Patients Withhigher-Risk Myelodysplastic Syndrome (MDS) Who Have Been Relapsing After, Or Are Refractory To, Hypomethylator Agent Therapy

▪ BackgroundTreatment with hypomethylating agents (HMA) such as azacitidine and decitabine has changed the overall outcome of patients with MDS. Failure to responed to or relapse from treatment with HMA carries a poor outcome and no approved therapy for these patients exists. Clofarabine is a second generation nucleoside analog with single agent activity in MDS. AimThis is a phase II trial to evaluate the safety and activity of the combination of clofarabine and low dose cytarabine in the treatment of patients with high risk MDS who failed prior HMA therapy. Material and MethodEligible were adults older than 18 years with MDS who have had no response, progressed, or relapsed following at least 4 cycles of therapy with either azacitidine and/or decitabine. Patients were required to have an ECOG performance status of </=2 at the time of study entry. Responses were defined according to IWG 2006 criteria. Induction therapy consisted of clofarabine 15 mg/m2 IV daily X 5 days (days 1-5) and cytarabine 20 mg SC twice daily X 7 days (days 1-7). Patients could receive up to 3 induction cycles as long as they tolerated the therapy and had stable disease. Responding patients proceeded with consolidation therapy with clofarabine 15 mg/m2IV daily X 3 days (days 1-3) and cytarabine 20 mg SC twice daily X 5 days (days 1-5) for a maximum of 12 cycles. Cycles were repeated every 4 to 8 weeks depending on hematopoietic recovery and resolution of toxicities. ResultsBetween January 2012 and March 2013, 29 patients were enrolled. The clinical characteristics are summarized in Table 1. Twenty four patients were evaluable for response (5 patients were too early for response). The overall response rate (ORR) was 50% (8 [33%] achieved complete remission (CR)/ complete remission with incomplete platelets recovery (CRp)/marrow CR, and 4 [17%] had stable disease with hematological improvement). With a median follow up of 4.9 months (range, 1.9-16.7), the median overall survival (OS) was 4.8 months (range, 0.5-13.5). Most toxicities were grade </= 2 and included: elevated liver enzymes in 41% of the patients, elevated bilirubin (38%), rash (28%), nausea (31%), headache (24%), and febrile neutropenia (28%). Grade >/= 3 toxicities included: elevated liver enzymes (3%) and elevated bilirubin (3%). Four-week mortality was 12%.Table 1Patient characteristicsN(%) / [range]Total29Median age, year6959-78Age > 65GenderMale2069Female931Prior chemotherapy931Prior radiotherapy724Performance status0-125862414DiagnosisRAEB1448RAEB-T1139CMML413IPSS scoreIntermediate-127Intermediate-21448High1345Cytogenetic analysisDiploid1345-5/5q- and -7/7q-414-5/5q- (sole)27-7/7q- (sole)13+82711q abnormalities13Miscellaneous621Median WBC X 1093.00.6-81.0Median hemoglobin g/dL9.12.8-13.6Median platelets x 10947.04.0-187.0Median bone marrow blasts %16.07.0 - 28Median peripheral blood blasts %3.00 - 22 ConclusionThe combination of clofarabine and low-dose cytarabine has an ORR of 50% in patients with MDS who failed prior therapy with HMA. The study continues to accrue and updated results with longer follow up will be presented at the meeting. Disclosures:Off Label Use: Clofarabine use in MDS. Faderl:Sanofi-Aventis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Clofarabine, idarubicin, and cytarabine (CIA) as frontline therapy for patients ≤60 years with newly diagnosed acute myeloid leukemia

Clofarabine is a second generation nucleoside analogue with activity in adults with acute myeloid leukemia (AML). A phase I trial of clofarabine, idarubicin, and cytarabine (CIA) in relapsed and refractory AML had shown an overall response rate (ORR) of 48%. To explore this combination further, we conducted a phase II study of (CIA) in patients with newly diagnosed AML ≤60 years. Patients ≥18-60 years with AML and adequate organ function were enrolled. Induction therapy consisted of clofarabine (C) 20 mg m⁻² IV daily (days 1-5), idarubicin (I) 10 mg m⁻² IV daily (days 1-3), and cytarabine (A) 1 g m⁻² IV daily (days 1-5). Patients in remission received up to six consolidation cycles (C 15 mg m⁻² × 3, I 8 mg m⁻² × 2, and A 0.75 g m⁻² × 3). Fifty-seven patients were evaluable. ORR was 79%. With a median follow up of 10.9 months, the median overall survival (OS) was not reached, the median event-free survival (EFS) was 13.5 months. Most toxicities were ≤grade 2. Four week mortality was 2%. In subgroup analysis, patients ≤40 years had better OS (P = 0.04) and EFS (P = 0.04) compared to patients >40 years. Compared to historical patients treated with idarubicin and cyarabine (IA), the OS and EFS were significantly longer for CIA treated patients. In multivariate analysis, CIA retained its favorable impact on OS compared to IA. Thus, CIA is an effective and safe therapy for patients ≤60 years with newly diagnosed AML.

Phase I Study of Oral Clofarabine Consolidation in Adults Aged 60 and Older With Acute Myeloid Leukemia

Abstract 3633 Background: Less than 16% of adults aged 60 and older diagnosed with acute myeloid leukemia (AML) will remain disease free after cytarabine consolidation. Clofarabine (clo) is a next generation nucleoside analogue whose IV formulation has shown considerable activity in older patients with AML considered unlikely to benefit from conventional therapy. This phase I trial is the first study of an oral formulation of clo for consolidation in patients >= 60 with AML who achieve a remission with cytotoxic induction regimens. Methods: The primary objective was to determine the maximum tolerated dose (MTD) and dose limiting toxicities (DLT) of oral clo on a 21 day dosing schedule for consolidation therapy. For safety reasons, the initial cohort was tested on a 14 day schedule. Tolerability of the regimen was a secondary objective. Six cohorts were tested (1 mg × 14 days, and 1 mg, 2 mg, 3 mg, 4 mg, and 6 mg × 21 days) with oral clo administered once daily for 14 or 21 days of a 28 day cycle, for up to 5 cycles. DLT were assessed during cycle 1 and defined as Grade 4 neutropenia lasting >=14 days or Grade 3–4 neutropenia with infection; Grade 4 thrombocytopenia >= 7 days or Grade 3–4 thrombocytopenia with bleeding; or Grade 3 or 4 non-hematologic toxicities with the exception of drug-related fever, alopecia, anorexia, or adequately treated nausea, vomiting and/or diarrhea. Results: Twenty patients were enrolled on the dose escalation phase of the study. Seventeen patients completed at least 1 cycle and were thus evaluable for response, while 3 patients were taken off study prior to completion of cycle 1 due to relapse. No DLTs were observed in any cohort. At the 1 mg dose, 3 patients completed all 5 cycles of therapy (2 on the 21 day schedule), 2 patients relapsed after 2 or 3 cycles, (21 day and 14 day schedule, respectively), and 1 patient withdrew after completion of cycle 1 (14 day schedule). At the 2 mg dose, 2 patients completed all 5 cycles and 1 patient relapsed after cycle 1. The 1 mg dose on both dosing schedules and the 2 mg dose were well-tolerated and did not require dose reductions. Of the 3 patients enrolled at the 3 mg dose, one completed 5 cycles with a dose reduction to 2 mg after the first cycle for intermittent grade 4 neutropenia, 1 patient completed 3 cycles with no evidence of disease, then received allogeneic transplant at the discretion of the treating physician, and the final patient completed 3 cycles with persistent grade 2–3 neutropenia and thrombocytopenia and was taken off study for evidence of minimal residual disease. In the 4 mg cohort, 2 patients completed 3 cycles and were subsequently taken off study, one to proceed to allogeneic transplant at the discretion of the treating physician and one for recurrent disease. A third patient completed 2 cycles and has proceeded to allogeneic transplant for recurrent disease. The fourth patient was dose reduced to 3 mg after the first cycle for grade 3 thrombocytopenia, completed a total of 3 cycles, and was subsequently taken off study for persistent cytopenias. One patient received the 6 mg dose and required 2 dose reductions (to 4mg and then 3 mg) for grade 3–4 neutropenia and thrombocytopenia. Therefore, enrollment at the 6 mg dose level was halted. Grade 1–2 non-hematologic toxicities occurring in >=30% of patients were fatigue, diarrhea, nausea, hyperbilirubinemia, elevated AST or ALT, infection, hyperglycemia, electrolyte abnormalities, hypoalbuminemia, dizziness, cough, SOB, and anxiety. Grade 3 non-hematologic toxicities included: fatigue (1), AST elevation (1), hyperglycemia (3), hyperbilirubinemia (1) and anxiety (1). These Grade 3 toxicities were transient and did not require dose reductions. No Grade 4 toxicities occurred. Conclusions: Oral clo consolidation is a well-tolerated regimen in adults aged 60 or older with acute myeloid leukemia in remission. Although the MTD is undefined as no DLTs occurred in any cohort, Grade 3–4 cytopenias halted enrollment at the 6 mg dose and patients in both the 3 and 4 mg cohorts required dose reductions subsequent to cycle 1 for cytopenias. Future studies investigating clo as a maintenance strategy appear feasible at 3 mg with an option to dose reduce in the setting of prolonged cytopenias. Disclosures: Off Label Use: Clofarabine is a purine nucleoside inhibitor indicated for the treatment of pediatric patients aged 1 to 21 with relapsed or refractory ALL. Cashen: Genzyme: Membership on an entity9s Board of Directors or advisory committees. Uy: Genzyme: Consultancy. Abboud: Genzyme: Membership on an entity9s Board of Directors or advisory committees, Research Funding.

Clofarabine in the Treatment of Elderly Patients with Acute Myeloid Leukemia

Elderly patients with acute myeloid leukemia (AML) have a poor outcome because of co- morbidities, poor tolerance to intensive chemotherapy and inherently more resistant disease. Clofarabine is a second generation nucleoside analogue which has shown promising activity in elderly patients with AML. This study was conducted to review the outcome of treatment with clofarabine in a group of such patients. The records of 5 elderly patients who were diagnosed to have AML and treated with clofarabine over a 12 month period were reviewed retrospectively. There were 2 female and 3 male patients with a median age of 68 years (range 65-82). At the time of treatment, 2 patients had newly diagnosed AML not considered suitable for intensive therapy, while 3 patients had partial or no response to conventional chemotherapy. The overall response rate was 100%, all patients achieving a complete remission. Induction and consolidation were well tolerated. All patients developed neutropenia with a median duration of 20 days (range 17-42). One patient developed hand and foot syndrome and a generalized rash but recovered. There was no mortality and all patients remained in remission after a median follow-up of 5.2 months (Range 3-10). Clofarabine (alone or in combination) is active in elderly AML patients with an acceptable safety profile and should be considered a potential option in this group.

The Use of Clofarabine and Cytarabine Combination (CLARA) As Salvage Therapy for Relapsed and/or Refractory Acute Myeloid Leukemia (AML)

AbstractAbstract 1518▪▪This icon denotes a clinically relevant abstractPatients with relapsed and/or refractory acute myeloid leukemia (AML) have a very dismal outcome and treatments are largely unsatisfactory. Salvage therapy is often limited by drug resistance and organ toxicities in patients who have already been exposed to multiple lines of chemotherapy. Clofarabine is a second generation nucleoside analogue with multiple mechanisms of action including inhibition of ribonucleotide reductase, suppression of DNA polymerase, direct DNA incorporation and induction of apoptosis. In this study, we evaluated the clinical outcome of patients with relapsed and/or refractory AML who received combination treatment of clofarabine and cytarbine (acronym CLARA) at Queen Mary Hospital in Hong Kong.The treatment with CLARA comprised clofarabine 40 mg/m2 and cytarabine 2 gm/m2 given intravenously for five days. For patients who relapsed after allogeneic hematopoietic stem cell transplantation (HSCT), CLARA was followed by the infusion of either BM or mobilized peripheral blood stem cells (PBSC) from the original donor and immunosuppression (cyclosporine A at 1.5 mg/kg twice daily) was given from day 8 after HSC infusion. All patients received standard anti-microbial prophylaxes and G-CSF support during neutropenia. Remission status was confirmed by bone marrow examination.Since 2009, a total of 55 patients have been recruited of whom 19 received CLARA at relapse after allogeneic HSCT. The median age of the patients was 45 years (range 20–64) and cytogenetic categorizations were favorable (N=7); intermediate (N=29) and unfavorable (N=14) in 50 evaluable patients. There were a median of two regimens (range 1–4) and five courses (range 1–12) of chemotherapy before CLARA. All patients developed grade 4 hematologic toxicity and 20% (no. of patients: grade 1–2=8; grade 3= 3) and 60% (grade 1–2=23; grade 3–4=10) developed dermatologic and liver toxicities. Six patients including three who relapsed after HSCT (out of 19 patients=16%) and three non-transplant patients (out of 36 patients=8%) died of treatment related mortality after CLARA (overall 11%). Twenty-seven patients (49%) achieved complete remission (CR) or CR with insufficient hematologic recovery (CRi). Patients who received CLARA for relapse post-HSCT had a higher CR/CRi (12 out 19 patients=63%) than the non-transplant patients (15 out of 36 patients=42%). The respective median disease-free (DFS) and overall-survivals (OS) of the post-HSCT relapse and non-transplant patients were 9.6 and 5.0 months (DFS) and 11.5 and 8.0 months (OS). CLARA is an effective salvage regimen for both post-HSCT relapse and non-transplant patients with tolerable side-effects. The optimal consolidation and maintenance strategies after CLARA would have to be further defined. Acknowledgments:Clofarabine was provided by a compassionate program from Sanofi-aventis Hong Kong Ltd. Disclosures:Off Label Use: Clofarabine.

Clofarabine, Idarubicin, and Cytarabine (CIA) As Frontline Therapy for Patients

AbstractAbstract 43▪▪This icon denotes a clinically relevant abstract BackgroundClofarabine is a second generation nucleoside analogue with activity in adults with AML. A recent randomized phase III study in relapsed AML showed higher response rates and better event-free survival (EFS) with the combination of clofarabine and cytarabine (CA) compared to cytarabine alone. A phase I/II trial of CIA in patients with relapsed/refractory AML had shown an overall response rate (ORR) of 38% (21% CR; 11% CRp). To explore this combination further, we conducted a phase II study of CIA in patients </= 60 years with previously untreated AML. Patients and MethodsEligible were patients >18–60 years with newly diagnosed AML and adequate renal and hepatic function. Patients were excluded for ECOG PS > 2, cardiac ejection fraction < 45%, or active and uncontrolled infection. For the first 30 patients, induction therapy consisted of Clofarabine (C) 22.5 mg/m2 iv daily (days 1–5), Idarubicin (I) 6 mg/m2 daily (days 1–3), and Cytarabine (A) 0.75 g/m2 daily (days 1–5). From patients 31 onward, induction doses were amended to C 20 mg/m2 × 5, I 10 mg/m2 × 3, and A 1 g/m2 × 5. Patients who did not achieve CR following induction could receive one re-induction course. Patients in CR/CRp/CRi continued with up to 6 consolidation cycles (C 22.5 mg/m2 × 3, I 6 mg/m2 × 2, and A 0.75 g/m2 × 3, subsequently amended to C 15 mg/m2 × 3, I 8 mg/m2 × 2, and A 0.75 g/m2 × 3). ResultsFrom April 2010 until February 2012, 59 patients were enrolled (Table 1). Fifty-seven patients were evaluable. Forty-two patients (74%) achieved CR and 3 (5%) CRp for an overall response rate of 79%. Ten patients required a re-induction {4/10 (40%) patients achieved CR, 2/10 (20%) achieved CRp). All patients received a median of 2 cycles (1–8 cycles), 24 (42 %) patients proceeded with an allogeneic stem cell transplant in first remission. With a median follow up of 10.9 months (1.6 - 23.1), the median OS was not reached, the median EFS was 13.5 months, and the median relapse free survival was not reached.Most toxicities were < grade 2. Toxicities > grade 2 included nausea (47%), rash (39 %), diarrhea (25%), elevated transaminases (23%), and elevated bilirubin (12%). Myelosuppression was ubiquitous but prolonged myelosuppression > 42 days was infrequent. Four week mortality was 2%. The response rate and toxicity were similar in both dose schedules. In subgroup analysis, patients < 40 years had better OS (HR 0.12, 95%CI, 0.02–0.90, P = 0.04) and EFS (HR 0.12, 95%CI, 0.02–0.93, P = 0.04) compared to patients > 40 years old. Compared to a historical group of patients who were treated with IA combination (I 12 mg/m2 IV daily × 3 plus A 1.5 g/m2 IV daily × 4) and after controlling for age, cytogenetics and other important clinical factors, the OS and EFS were significantly higher (P = 0.005, 0.0001, respectively) for CIA treated patients. Furthermore, in multivariate analysis, CIA retained its superior impact on OS (HR 0.53, 95% CI, 0.29 to 0.97, P =0.03) and EFS (HR 0.40, 95% CI, 0.22 to 0.73, P =0.003) compared to IA. ConclusionCIA is an active combination for patients </= 60 years with newly diagnosed AML. Patients < 40 years had significantly better OS and EFS. Compared to IA alone, CIA achieved significantly longer OS and EFS. A randomized comparison with standard induction therapy will be needed to further assess the role of CIA in frontline AML therapy of younger patients.Table 1Patient's characteristicsParameterPatients No.59Median age, years, (range)48 (17–60)Median WBC X 109/L, (range)3.2 (6–100.2)Median hemoglobin g/dl, (range)9.3 (7.3–14.6)Median platelets 103/mL, (range)49 (6–270)Median peripheral blood blast %, (range)12 (0–94)Median bone marrow blast %, (range)42 (3–92)ECOG performance status > 2, No. (%)4 (7)AML history, No. (%)de novo40 (68)MDS-related10 (17)Therapy-related8 (13)Mixed phenotype1 (2)Cytogenetic abnormalities*, No. (%)Diploid21 (36)Intermediate14 (25)Unfavorable20 (34)Insufficient metaphases3 (5)Molecular abnormalities, No. (%)FLT3-ITD6 (10)NPM18 (14)RAS4 (7)CEBPa4 (7)Abbreviations: AML: acute myeloid leukemia, MDS: myelodysplastic syndrome, FLT3-ITD: FMS-like tyrosine kinase-3 internal tandem duplication, NPM1: nucleophosmin 1, CEBPa: CCAAT/enhancer-binding protein alpha.*Defined as per the MRC criteria Disclosures:Off Label Use: 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.

Clofarabine, Idarubicin, and Cytarabine (CIA) As Frontline Therapy for Patients Younger Than 61 Years with Newly Diagnosed Acute Myeloid Leukemia (AML)

Abstract 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.

Phase I Study of Oral Clofarabine Consolidation in Adults Aged 60 and Older with Acute Myeloid Leukemia,

Abstract 3633 Background:Less than 16% of adults aged 60 and older diagnosed with acute myeloid leukemia (AML) will remain disease free after cytarabine consolidation. Clofarabine (clo) is a next generation nucleoside analogue whose IV formulation has shown considerable activity in older patients with AML considered unlikely to benefit from conventional therapy. This phase I trial is the first study of an oral formulation of clo for consolidation in patients >= 60 with AML who achieve a remission with cytotoxic induction regimens. Methods:The primary objective was to determine the maximum tolerated dose (MTD) and dose limiting toxicities (DLT) of oral clo on a 21 day dosing schedule for consolidation therapy. For safety reasons, the initial cohort was tested on a 14 day schedule. Tolerability of the regimen was a secondary objective. Six cohorts were tested (1 mg × 14 days, and 1 mg, 2 mg, 3 mg, 4 mg, and 6 mg × 21 days) with oral clo administered once daily for 14 or 21 days of a 28 day cycle, for up to 5 cycles. DLT were assessed during cycle 1 and defined as Grade 4 neutropenia lasting >=14 days or Grade 3–4 neutropenia with infection; Grade 4 thrombocytopenia >= 7 days or Grade 3–4 thrombocytopenia with bleeding; or Grade 3 or 4 non-hematologic toxicities with the exception of drug-related fever, alopecia, anorexia, or adequately treated nausea, vomiting and/or diarrhea. Results:Twenty patients were enrolled on the dose escalation phase of the study. Seventeen patients completed at least 1 cycle and were thus evaluable for response, while 3 patients were taken off study prior to completion of cycle 1 due to relapse. No DLTs were observed in any cohort. At the 1 mg dose, 3 patients completed all 5 cycles of therapy (2 on the 21 day schedule), 2 patients relapsed after 2 or 3 cycles, (21 day and 14 day schedule, respectively), and 1 patient withdrew after completion of cycle 1 (14 day schedule). At the 2 mg dose, 2 patients completed all 5 cycles and 1 patient relapsed after cycle 1. The 1 mg dose on both dosing schedules and the 2 mg dose were well-tolerated and did not require dose reductions. Of the 3 patients enrolled at the 3 mg dose, one completed 5 cycles with a dose reduction to 2 mg after the first cycle for intermittent grade 4 neutropenia, 1 patient completed 3 cycles with no evidence of disease, then received allogeneic transplant at the discretion of the treating physician, and the final patient completed 3 cycles with persistent grade 2–3 neutropenia and thrombocytopenia and was taken off study for evidence of minimal residual disease. In the 4 mg cohort, 2 patients completed 3 cycles and were subsequently taken off study, one to proceed to allogeneic transplant at the discretion of the treating physician and one for recurrent disease. A third patient completed 2 cycles and has proceeded to allogeneic transplant for recurrent disease. The fourth patient was dose reduced to 3 mg after the first cycle for grade 3 thrombocytopenia, completed a total of 3 cycles, and was subsequently taken off study for persistent cytopenias. One patient received the 6 mg dose and required 2 dose reductions (to 4mg and then 3 mg) for grade 3–4 neutropenia and thrombocytopenia. Therefore, enrollment at the 6 mg dose level was halted. Grade 1–2 non-hematologic toxicities occurring in >=30% of patients were fatigue, diarrhea, nausea, hyperbilirubinemia, elevated AST or ALT, infection, hyperglycemia, electrolyte abnormalities, hypoalbuminemia, dizziness, cough, SOB, and anxiety. Grade 3 non-hematologic toxicities included: fatigue (1), AST elevation (1), hyperglycemia (3), hyperbilirubinemia (1) and anxiety (1). These Grade 3 toxicities were transient and did not require dose reductions. No Grade 4 toxicities occurred. Conclusions:Oral clo consolidation is a well-tolerated regimen in adults aged 60 or older with acute myeloid leukemia in remission. Although the MTD is undefined as no DLTs occurred in any cohort, Grade 3–4 cytopenias halted enrollment at the 6 mg dose and patients in both the 3 and 4 mg cohorts required dose reductions subsequent to cycle 1 for cytopenias. Future studies investigating clo as a maintenance strategy appear feasible at 3 mg with an option to dose reduce in the setting of prolonged cytopenias. Disclosures:Off Label Use: Clofarabine is a purine nucleoside inhibitor indicated for the treatment of pediatric patients aged 1 to 21 with relapsed or refractory ALL. Cashen:Genzyme: Membership on an entity's Board of Directors or advisory committees. Uy:Genzyme: Consultancy. Abboud:Genzyme: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Addition of Clofarabine to TLI/ATG Conditioning: Impact on Immune Reconstitution and Clinical Outcomes,

Abstract 4066▪▪This icon denotes a clinically relevant abstractThe fundamental challenge in designing an effective conditioning regimen for allogeneic transplantation involves the prevention of disease relapse while minimizing the risk for Graft versus Host Disease (GVHD). Treatment with total lymphocyte irradiation (TLI) and anti-thymocyte globulin (ATG) has been shown to minimize the risk of GVHD through the biasing of the T cell reconstitution towards an inhibitory phenotype. However, disease relapse remains a significant concern. Clofarabine is a second generation nucleoside analog with potent cytoreductive capacity and demonstrates efficacy in hematological malignancies. In this study, we examined the combination of clofarabine, TLI and ATG with respect to T cell reconstitution, risk for GVHD and transplant outcome. Sequential cohorts of 5 patients were treated with TLI and ATG alone or in conjunction with 20 mg/m2, 30 mg/m2 or 40 mg/m2 of clofarabine for 5 days. Cyclosporine and mycophenolate mofetil were administered as GVHD prophylaxis. Twenty patients have been enrolled (5 AML/MDS, 2 ALL, 6 lymphoma, 2 CLL, 5 myeloma) and received HLA matched peripheral blood stem cells collected from related (N=11) and unrelated donors (N=9). Of 19 evaluable patients, 15 are alive with a median follow up of 665 days. Day 30 and 100 mortality was 0% for TLI and ATG and 0% and 10% for those receiving clofarabine. The maximum tolerated dose (MTD) of clofarabine was 30 mg/m2 as 2 patients experienced treatment related mortality at the 40 mg/m2 dose level. Grade 5 infections and multiorgan failure occurred in both patients. All patients demonstrated engraftment with mean bone marrow donor chimerism of 92.5% at Day 30. The first cohort’s ANC did not drop below 500 cells/uL, while median time to neutrophil engraftment in the patients who received clofarabine was 9 days. The median time to platelet recovery was 11 and 12 days for patients receiving TLI and ATG alone or with clofarabine, respectively (p=0.39). T cell reconstitution studies demonstrated a significant decrease in CD4+ cells to (<200 cells/uL) persisting for more than 6 months and a more than a two fold increase in circulating CD56+ NK cells. No significant decrease in CD8 T cells in the early post-transplant period was seen in either group. The mean percentage of regulatory T cells (CD4+/25+/FoxP3+) rose in the early post-transplant period following TLI and ATG (5.5 to 14.2% from baseline to day 30; p=0.015), but not in those receiving clofarabine (8.1 to 6%; p=0.15). Assessment of T cell polarization at these time points demonstrated a two fold increase in CD8+ T cells expressing IL-4 at Day 30 in patients receiving TLI and ATG alone (p=0.04); but not following clofarabine containing conditioning. Consistent with these findings, the incidence of grade II-IV GVHD was 0% and 42% in those receiving TLI and ATG alone or in conjunction with clofarabine, respectively. cGVHD was seen in 20% and 42% of patients, respectively. In contrast, disease progression was seen in 60% of patients receiving TLI and ATG alone as compared to 27% receiving clofarabine, TLI, and ATG. In summary, the addition of clofarabine to TLI and ATG conditioning resulted in a decrease in circulating regulatory T cells, decreased CD8+ T cell expression of IL-4, and was associated with an increased risk of GVHD and a potential for a decrease in the risk of relapse. Disclosures:Chen:Genzyme: Membership on an entity's Board of Directors or advisory committees. Avigan:Genzyme: Research Funding.

Phase II Study of the Combination of Clofarabine Plus Idarubicin and Cytarabine (CIA) In Patients with Relapsed/Refractory Acute Myeloid Leukemia (AML).

AbstractAbstract 1061Clofarabine is a second generation nucleoside analog with activity in patients with acute leukemias. Previous studies with the combination of clofarabine plus cytarabine have reported a complete remission rate (CR) of 24% in relapsed AML and 52% in previously untreated AML patients. To explore further combinations with drugs active in AML, we conducted a phase II study of CIA in patients with relapsed and primary refractory AML. Patients were treated at the maximum tolerated dose (MTD) determined from a preceding phase I study: clofarabine 22.5mg/m2 IV daily × 5, idarubicin 6 mg/m2 IV daily × 3, and cytarabine 0.75 g/m2 IV daily × 5 days. A total of 63 patients were enrolled. Patients with prior exposure to clofarabine were not eligible. The median age was 51years (18 - 80years). Twenty-four patients were primary refractory and 39 had relapsed disease. All the patients received CIA in 1st salvage. For patients with relapsed AML, the median duration of the first CR was 36 weeks (3 – 215 weeks). Three patients underwent stem cell transplant (SCT) prior to treatment with CIA and 28 patients had received at least intermediate doses of cytarabine prior to relapse. Fifteen patients had secondary AML following a preceding phase of MDS. Twenty-five percent of patients had -5/-7 and 6% had trisomy 8. Thirteen patients (21%) achieved CR, 7 (11%) CRp (complete remission without platelet recovery), and 4 (6%) a partial remission (PR) for an overall response rate of 38%. The response rate in patients with primary refractory disease was 33% while the response rate in patients with relapsed disease was 41%. Five patients (8%) died during induction (</= 28 days); 4 from septic shock and 1 from diffuse alveolar hemorrhage. Median duration of follow-up was 65 weeks (range 6–161). Median overall survival was 34 weeks (range 1–161). Disease free survival for those patients who achieved CR/CRp was 66 weeks (range 4–156). A total of 24 (38%) patients underwent SCT following CIA. The most common toxicity was nausea/vomiting in 49 (78%) patients followed by hepatic dysfunction in 43 (68%) patients and diarrhea in 42 (67%) patients. In summary, the CIA combination has activity in patients with relapsed/refractory AML. Further evaluation in better prognosis patients is ongoing. Disclosures:Ravandi:Genzyme: Honoraria, Membership on an entity's Board of Directors or advisory committees. Kantarjian:Genzyme: Research Funding. Faderl:Genzyme: Research Funding.

Treatment of chronic hepatitis B with Telbivudine alone or in combination with nucleotide analogues

Introduction: Telbivudine is a new generation nucleoside analogue which was recently approved for treatment of chronic hepatitis B (CHB). Other than in clinical trials there has been only limited experience with this drug in clinical practice. Patients and study design: A total of 39 patients with CHB received Telbivudine as first line therapy (n=29) or as an add-on to a previously failed therapy with Adefovir (n=10). Patients who did not show virological response to the initial treatment with Telbivudine after 24 weeks were addionally treated with Tenofovir. Virological resistance was analyzed retrospectively. The serum levels of HBV-DNA were meassured at week 4, 12, 24, 28, 36, and 48. Results: Telbivudine was well tolerated. Of the 29 patients who received Telbivudine as first line therapy, 61% achieved complete virological response with undetectable HBV-DNA-levels at week 24. Of those, 15% showed detectable HBV-DNA at week 48. However, all patients had very low HBV-DNA-levels (&lt;357 IU/ml). Ten patients received Tenofovir as an add-on at week 24. Of those, only 20% achieved a complete virological response at week 48. Of the ten patients who received Telbivudine as an add-on to Adefovir, only 20% achieved a complete virological response at week 24. Patients who did not repond to a therapy containing Telbivudine had a significantly higher viral load at baseline than patients who achieved a complete virological response (250.289.000 vs. 2.077.500 IU/ml, p=0.007). Resistance analysis revealed only two patients with Lamivudine- and Entecavir-resistant mutations. Both failed to achieve a complete virological response. Conclusion: Telbivudine is a safe and efficient treatment alternative for patients with CHB with high response rates in patients with no resistant mutations and a moderate viral load. Only a minority of patients who failed to respond to either Telbivudine or Adefovir monotherapy seem to benefit from combining Telbivudine with nucleotide analogues.

Clofarabine (CLO) Has Single Agent Activity in Relapsed and Refractory Non-Hodgkin Lymphoma (NHL) Including Rituximab (R)-Refractory Patients (pts).

Abstract 921 Background:CLO is a second generation nucleoside analogue with known activity in acute leukemia and myelodysplasia. As there is no standard therapy for refractory and transplant-ineligible relapsed NHL, and given the activity that purine analogues have in lymphoid malignancies, we sought to investigate the activity of CLO in this pt population regardless of histology. Methods:Eligible pts had measurable disease by CT and/or PET, ECOG performance status ≤ 2, and adequate renal, cardiac, liver, and bone marrow function (unless cytopenias were disease-related). CLO was given in the outpatient setting intravenously over 1-hour days 1-5 every 28 days for 6 cycles maximum. All pts received anti-viral and anti-pneumocystis jiroveci prophylaxis. First, we initiated a phase I portion using a standard 3×3 study design. CLO was given at 4 mg/m2 in cohort 1 with subsequent cohorts to be escalated by 2 mg/m2 each. Once the maximum tolerated dose (MTD) was determined, the phase II portion of this study was initiated at the MTD. All pts were followed until disease progression. Results:Thirty-three pts (18 females, 15 males) have been enrolled (7 in the phase I portion and 26 in the phase II), of which 29 are evaluable for response and/or toxicity (2 just started therapy, 1 taken off due to persistent cytopenias, and 1 withdrew consent). Median age was 69 years (range 27-88), median number of prior therapies was 3 (range 1-8), with 21% failing prior stem cell transplantation and 74% being R-refractory. Median time from original diagnosis to first CLO treatment was 36 months (range 6-216). Histologies included 12 diffuse large cell, 5 follicular, 5 small lymphocytic, 4 anaplastic large T-cell, and 1 each for Richter, mantle cell, marginal zone, peripheral T-cell, transformed, non-specific T-cell, and mixed histology. Median number of CLO cycles was 4 (range 1-6). Thrombocytopenia was the dose-limiting toxicity at 6 mg/m2 in 2/6 pts. The MTD recommended for phase II was 4 mg/m2. With a median follow up of 8 months (range 1-33), 7 pts (24%) showed complete response (CR) and 8 (27%) had partial response (PR) for an overall response rate of 51%. Four pts (13%) demonstrated stable disease and 10 (34%) showed progression. Median duration of response was 7 months (range 2-33+) with 6 pts continuing in remission including a patient who is undergoing stem cell transplantation. Median time to progression (TTP) was 3.5 months with median overall survival of 8 months. sEVEN pts (24%) remain progression-free. Of patients who were followed for more than 12 months, 60% were alive at 1-year. Five of the CR pts were of low-grade histology while only 2 had large cell lymphoma. All pts required growth factor support. Toxicity was mainly hematologic with 63% experiencing grade 3/4 thrombocytopenia, 60% grade 3/4 neutropenia, and 39% grade3/4 anemia, and 63%. Grade 3 and/or 4 non-hematologic toxicity included 2 (6%) with tumor lysis syndrome, 2 (6%) infectious episodes (pneumonia and bilateral cellulitis), 2 (6%) renal insufficiency, 2 (6%) fatigue, 1 (3%) seizure activity, 1 (3%) pleural effusion, and 1 hypokalemia (3%). No treatment-related mortality. Conclusions:CLO is active in heavily pre-treated B-cell NHL including R-refractory pts. Activity appears more pronounced in low-grade histology. The drug is well-tolerated and can be administered as an outpatient. Reversible myelosuppression is the major toxicity. Future studies in front-line in combination with R are warranted. Disclosures:Nabhan:Bayer: Honoraria, Research Funding, Speakers Bureau; Genzyme: Research Funding; Genentech: Honoraria, Speakers Bureau. Venugopal:Genzyme: Honoraria, Research Funding; Genentech: Honoraria, Research Funding, Speakers Bureau.

Phase I-II Study of Clofarabine-Melphalan-Alemtuzumab (CMA) Conditioning for Allogeneic Hematopoietic Cell Transplantation (HCT) in Patients with Advanced Hematologic Malignancies: Determination of MTD and Outcomes.

Abstract 197Supported by an unrestricted grant from Genzyme Corporation.Fludarabine (Flu) melphalan-alemtuzumab is a well tolerated, reduced intensity conditioning regimen for HCT. Clofarabine (Clo), a second generation nucleoside analog with excellent activity in acute leukemia, might enhance disease control over Flu. We report outcomes of a completed phase I and ongoing phase II study of CMA conditioning for allogeneic peripheral blood HCT. Tacrolimus was administered as GVHD prophylaxis. For the phase I cohort, one pt was enrolled per dose level, until the first DLT or until 2 had grade 3 toxicity. Dose level 1 consisted of: clo 10 mg/m2/day on d −7 to −3 and melphalan 100 mg/m2 on day −2. Clo was increased by 10 mg/m2/day per cohort until 40 mg/m2/day. Then, melphalan was increased by 20 mg/m2 until 140 mg/m2. Alemtuzumab was given at a fixed dose of 20 mg/day on d −7 to −3. Twelve pts were accrued in the phase I portion of whom three remain in remission at 26, 22 and 21 months.Forty pts, median age 53 (24–69), have been accrued in the phase II study of whom 16 had related and 24 unrelated donors. 20 had AML/MDS (6 refractory, 4 CR2, 9 CR1, 1 untreated MDS), 16 NHL (6 refractory, 9 chemosensitive relapse, 1 CR1) 2 CLL, 2 MPD. ASBMT risk score was high in 14, intermediate in 14, and low in 12. Performance score was 0 in 19, 1 in 17, 2 in 2, and not documented in 2 patients. The phase II dose was initiated at Clo 40 mg/m2/day x 5 days and melphalan 140 mg/m2. Twenty-four pts received this dose. Grade 3 renal toxicity occurred between day −7 and day +7 in 4 of 24 (17%) pts receiving this dose. The phase II dose was then reduced to Clo 30 mg/m2/day x 5 days and melphalan 140 mg/m2, and used to treat 16 pts. One pt with preexisting cardiomyopathy and refractory AML died during conditioning from cardiovascular failure. No grade 3 renal toxicity has been observed in this cohort and 3 pts had reversible grade 2 renal failure. Other toxicities included: gr 2–3 reversible ALT elevation between day −2 and day +5 in 8 pts; gr 2 reversible bilirubin elevation in 1 pt. No grade 3–4 hand foot syndrome or VOD occurred in this cohort.All evaluable pts engrafted. Twenty of 24 pts had full donor CD3 chimerism on day 30 and 2 had mixed donor chimerism. 11 pts had gr II aGVHD, and 3 had gr IIII/IV aGVHD. 7 have cGVHD.With a median follow-up of 313 days (19–607), 24 of 40 pts (60%) in the phase II portion of the study remain in remission. Eight have relapsed, 4 of whom have died. Eight others have died of treatment-related causes (7 after Clo 40 and 1 after Clo 30). Estimated one year survival is 72% (95%CI, 56–88) and PFS is 63% (45–81%). Neither dose of Clo (40 vs 30), donor type (MUD vs related), age (< 50 vs >50) affected outcomes. One year PFS was 56% (28–84) for NHL and 68% (46–90) for AML/MDS (P=NS). One year PFS was 43% (15–71%) for ASBMT high risk pts vs 70% (50–90%) for ASBMT low/intermediate risk pts (P=0.01; Figure 1). Conclusions: Clofarabine - melphalan - alemtuzumab conditioning induces durable remissions in a substantial fraction of patients with advanced hematologic malignancies. Clo 30/Mel 140 has an excellent safety profile. [Display omitted] Disclosures:Off Label Use: clofarabine for transplant conditioning. Kline:Genzyme corporation: Membership on an entity's Board of Directors or advisory committees. Odenike:Genzyme corporation: Membership on an entity's Board of Directors or advisory committees. Stock:Genzyme: Research Funding.

Clofarabine in the treatment of poor risk acute myeloid leukaemia

Clofarabine is a second generation nucleoside analogue. It inhibits DNA repair and activates the mitochondrial apoptotic pathway leading to cell death. In vitro clofarabine has demonstrated synergy with daunorubicin and Ara-C and in phase II clinical trials has shown promising activity in poor risk Acute myeloid leukaemia (AML) patients. In our institution over a 24 month period 22 AML patients (11 M, 11 F) with poor risk features, deemed unsuitable for standard therapy, were treated with clofarabine, alone (eight patients) or in combination (14 patients) for up to three cycles of treatment. The median age was 67.5 years (24-76) with 16 patients > 60 years. At the time of treatment 18 patients had active AML. Four patients intolerant of standard induction received clofarabine as consolidation. The overall response rate (ORR) for the 18 patients with active AML was 61%, nine patients (50%) achieving a complete response (CR). Induction and consolidation were well tolerated with no unexpected toxicities. Predictably, all patients developed grade 4 neutropenia but the median duration was only 20 days (17-120). Induction mortality was acceptable at 17%. In conclusion, clofarabine (alone or in combination) is active in poor risk AML with an acceptable safety profile and should be considered a potential option in poor risk AML patients.

Results of a phase I study of clofarabine (CLO) plus cyclophosphamide (CY) in adult patients (pts) with relapsed and/or refractory acute lymphoblastic leukemia (ALL)

7020 Background: CLO is a second generation nucleoside analog with FDA approval for children with ALL relapse. Single agent CLO in adult ALL was less active so that combinations of CLO with other active agents are pursued. As CLO inhibits DNA repair following exposure to DNA damaging agents, we designed a phase I study of the combination of CLO with CY. Methods: Pts ≥ 21 years (yrs) with primary refractory or relapsed ALL, NYHA class &lt; 3, and a cardiac ejection fraction ≥ 45% were eligible. The continual reassessment method (CRM) was used to determine the maximum tolerated dose (MTD) from 4 pre-defined dose levels. The starting dose level was CLO 40 mg/m2 i.v. daily x 3d and CY 200 mg/m2 i.v. q12h x 3d. For cohort 2, CY was 300 mg/m2 and cohorts 3 and 4 maintained these doses with the treatment duration extended to 4 and 5 days, respectively. Results: Thirty pts have been enrolled. Median age was 28 yrs (range 21–72). Twenty-one pts had pre-B ALL, 5 pts pre-T/T ALL, 1 pt mature B ALL, and 3 pts biphenotypic acute leukemias. Karyotype was diploid in 10 pts and 2 pts had Ph+ ALL. Median number of prior regimens was 2 (1–5). Seven (23%) pts were primary refractory. Among the remainder, preceding median remission duration was 8.6 mos (1–39 mos). Five pts were treated in cohort 1 and 25 in cohort 2. One (20%) pt in cohort 1 and 9 (36%) in cohort 2 experienced DLTs (≥ grade 3) including transaminase elevations, diarrhea, hyperbilirubinemia, and (1 pt each) elevation of creatinine/renal failure, lipase elevation, rash, nausea/vomiting. Evaluable for response were 28 pts: 3 CR (one pt in cohort 1) and 1 marrow CR (OR 14%). All pts had pre-B ALL. One pt had Ph+ ALL, and one was primary refractory to HCVAD. Three early deaths due to infectious complications occurred (all in cohort 2). Conclusions: The MTD for this combination is CLO 40 mg/m2 i.v. daily x 3d and CY 200 mg/m2 i.v. q12h x 3d. DLT are mainly GI-related. A phase II extension is ongoing and will focus on efficacy data. [Table: see text]

Bone marrow CFU-GM and human tumor xenograft efficacy of three antitumor nucleoside analogs

Nucleoside analogs are rationally designed anticancer agents that disrupt DNA and RNA synthesis. Fludarabine and cladribine have important roles in the treatment of hematologic malignancies. Clofarabine is a next generation nucleoside analog which is under clinical investigation. The bone marrow toxicity, tumor cell cytotoxicity and human tumor xenograft activity of fludarabine, cladribine and clofarabine were compared. Mouse and human bone marrow were subjected to colony forming (CFU-GM) assays over a 5-log concentration range in culture. NCI-60 cell line screening data were compared. In vivo, a range of clofarabine doses was compared with fludarabine for efficacy in several human tumor xenografts. The IC90 concentrations for fludarabine and cladribine for mouse CFU-GM were >30 and 0.93 microM, and for human CFU-GM were 8 and 0.11 microM, giving mouse to human differentials of >3.8- and 8.5-fold. Clofarabine produced IC90s of 1.7 microM in mouse and 0.51 microM in human CFU-GM, thus a 3.3-fold differential between species. In the NCI-60 cell line screen, fludarabine and cladribine showed selective cytotoxicity toward leukemia cell lines while for clofarabine there was no apparent selectivity based upon origin of the tumor cells. In vivo, clofarabine produced a dose-dependent increase in tumor growth delay in the RL lymphoma, the RPMI-8226 multiple myeloma, and HT-29 colon carcinoma models. The PC3 prostate carcinoma was equally responsive to clofarabine and fludarabine. Bringing together bone marrow toxicity data, tumor cell line cytotoxicity data, and human tumor xenograft efficacy provides valuable information for the translation of preclinical findings to the clinic.