Clofarabine

PURPOSE: Ribonucleotide reductase (RR) enzymes (RR1 and RR2) play an important role in the reduction of ribonucleotides to deoxyribonucleotides which is involved in DNA replication and repair. Augmented RR activity has been ascribed to uncontrolled cell growth and tumorigenic transformation. METHODS: This review mainly focuses on several biological and chemical RR inhibitors (e.g., siRNA, GTI-2040, GTI-2501, triapine, gemcitabine, and clofarabine) that have been evaluated in clinical trials with promising anticancer activity from 1960's till 2016...

Clofarabine containing chemotherapeutic regimens have demonstrated efficacy in the treatment of relapsed refractory acute myeloid leukemia. Nonetheless, there are limited data on the use of clofarabine in patients with renal failure. The present report describes the use of clofarabine in a patient with renal failure undergoing intermittent dialysis. We describe our rationale for dosing, clofarabine plasma levels obtained, and discuss our findings in the context of other available literature. Consistent with previous findings, intermittent hemodialysis was not found to be a reliable method of removing clofarabine in patients with renal insufficiency...

In patients with relapsed or refractory (r/r) acute myeloid leukemia (AML), allogeneic hematopoietic stem cell transplantation (HSCT) is considered to be the only treatment providing long-term disease control. The BRIDGE trial studied the safety and efficacy of a clofarabine-based salvage therapy before HSCT in patients with r/r AML. Here, we report the long-term follow-up of this phase II multicenter trial and exploratory analyses on the impact of comorbidity on outcome. Eighty-four patients with a median age of 61 years (range, 40 to 75) were enrolled...

Common side effects of clofarabine (CFB) are liver toxicity, particularly a transient elevation of transaminases and skin toxicity. We studied the correlation of pharmacokinetic (PK) parameters with these toxicities and the efficacy of CFB in patients with relapsed or refractory acute myeloid leukemia. Clofarabine PK parameters showed large inter-individual variability. A higher CFB area under the curve was significantly associated with higher transaminase levels (p = .011 for aspartate aminotransferase (AST), adjusted for age, sex, cumulated CFB dosage, baseline AST, and glomerular filtration rate (GFR))...

Patients with high risk myelodysplastic syndromes (MDS) and acute myelogenous leukemia (AML) are commonly older with multiple co-morbidities, rendering them unsuitable for intensive induction chemotherapy or transplantation. We report preliminary cellular immune profiling of four cases receiving sequential clofarabine and lenalidomide for high risk MDS and AML in a phase I study. Our results highlight the potential of immune profiling for monitoring immune-modifying agents in high risk MDS and AML.

To date, over 100 small molecule oncology drugs have been approved by the US Food and Drug Administration.  Due to the inherent heterogeneity of tumors, these small molecules are often administered in combination to prevent emergence of resistant cell subpopulations.  Therefore, new combination strategies to overcome drug resistance in patients with advanced cancer are needed.  In this study, we performed a systematic evaluation of the therapeutic activity of over 5,000 pairs of FDA-approved cancer drugs against a panel of 60 well-characterized human tumor cell lines (NCI-60) to uncover combinations with greater than additive growth-inhibitory activity...

In allogeneic hematopoietic cell transplantation (HCT) it has been shown that over- or underexposure to conditioning agents have an impact on patient outcomes. Conditioning regimens combining busulfan (Bu) and fludarabine (Flu) with or without clofarabine (Clo) are gaining interest worldwide in HCT. To evaluate and possibly adjust full conditioning exposure a simultaneous analysis of Bu, F-ARA-A (active metabolite of Flu) and Clo in one analytical run would be of great interest. However, this is a chromatographical challenge due to the large structural differences of Bu compared to F-ARA-A and Clo...

Purpose: To investigate the biologic and clinical significance of ribonucleotide reductase (RR) in multiple myeloma (MM). <p>Experimental Design: We assessed the impact of RR expression on patient outcome in MM. We then characterized the effect of genetic and pharmacological inhibition of RRM1 on MM growth and survival using siRNA and clofarabine (CLO), respectively, both in vitro and in vivo mouse xenograft model.</p> <p>Results: Newly diagnosed MM patients with higher RRM1 expression have shortened survival...

Recently, we demonstrated that sterile α motif and HD domain containing protein 1 (SAMHD1) is a major barrier in acute myelogenous leukemia (AML) cells to the cytotoxicity of cytarabine (ara-C), the most important drug in AML treatment. Ara-C is intracellularly converted by the canonical dNTP synthesis pathway to ara-CTP, which serves as a substrate but not an allosteric activator of SAMHD1. Using an AML mouse model, we show here that wild type but not catalytically inactive SAMHD1 reduces ara-C treatment efficacy in vivo...

Purine nucleoside analogues are widely used in the treatment of haematological malignancies, and their biological activity is dependent on the intracellular accumulation of their triphosphorylated metabolites. In this context, we developed and validated a liquid chromatography tandem mass spectrometry (LC-MS/MS) method to study the formation of 5'-triphosphorylated derivatives of cladribine, fludarabine, clofarabine and 2'-deoxyadenosine in human cancer cells. Br-ATP was used as internal standard. Separation was achieved on a hypercarb column...

Clofarabine is a purine nucleoside analog with immunosuppressive and antileukemic activity and its inclusion in reduced-intensity regimens could potentially improve outcomes. We performed a prospective phase I study of clofarabine combined with 2 Gy total body irradiation (TBI) as a nonmyeloablative preparative regimen for allogeneic stem cell transplantation in pediatric patients who were considered at high risk of mortality from standard myeloablative regimens. The main goal of the study was to delineate the maximum feasible dose (MFD) of clofarabine in combination with 2 Gy TBI...

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We describe a relapsed AML patient who had two prior severe reactions to clofarabine involving rigors, emesis, tachycardia, hypotension, and acute kidney injury. Given previous prolonged remission achieved with clofarabine and cytarabine therapy years prior, rechallenge was undertaken upon discovery of AML relapse. We designed a desensitization protocol performed with the first dose of clofarabine, leading to successful administration of the entire clofarabine/cytarabine treatment course. From this case we show promise for clofarabine rechallenge after prior hypersensitivity reactions in patients with few treatment options for relapsed AML...

Purpose To evaluate the efficacy and safety of a clofarabine-based combination (CLARA) versus conventional high-dose cytarabine (HDAC) as postremission chemotherapy in younger patients with acute myeloid leukemia (AML). Patients and Methods Patients age 18 to 59 years old with intermediate- or unfavorable-risk AML in first remission and no identified donor for allogeneic stem-cell transplantation (SCT) were eligible. Two hundred twenty-one patients were randomly assigned to receive three CLARA or three HDAC consolidation cycles...

SAMHD1 is an intracellular enzyme that specifically degrades deoxynucleoside triphosphates into component nucleoside and inorganic triphosphate. In myeloid-derived dendritic cells and macrophages as well as resting T-cells, SAMHD1 blocks HIV-1 infection through this dNTP triphosphohydrolase activity by reducing the cellular dNTP pool to a level that cannot support productive reverse transcription. We now show that, in addition to this direct effect on virus replication, manipulating cellular SAMHD1 activity can significantly enhance or decrease the anti-HIV-1 efficacy of nucleotide analogue reverse transcription inhibitors presumably as a result of modulating dNTP pools that compete for recruitment by viral polymerases...

For refractory or relapsed acute myeloid leukemia patients, allogeneic hematopoietic stem cell transplantation is the only curative treatment option, but the disease must be in remission before this can be attempted. "Salvage" therapy regimens containing high-dose cytarabine plus fludarabine or cladribine with or without anthracyclines or plus mitoxantrone and etoposide fail in 30-50% of cases. We report the outcome of 14 patients treated with a clofarabine-based treatment administered after at least one failed fludarabine-based "salvage" attempt in a "real life" (outside a clinical trial) context...

Haploidentical hematopoietic cell transplantation (HCT) conditioning with clofarabine and target area under the blood concentration-time curve (AUC)-based busulfan adjustment was performed in three patients with refractory pediatric leukemia. The target AUC for two patients who had already received multiple transplantations was 3600 and 4000 μmol min/L, and that for the patient with Down's syndrome was 3000 μmol min/L. Regimen-related toxicity was well tolerated in all cases. All three maintained cytological remission throughout the follow-up period (between 31 and 167 weeks)...

Clofarabine has demonstrated antileukemic activity in acute myeloid leukemia (AML) but has yet to be critically evaluated in younger adults in the frontline with standard chemotherapy. We compared two induction regimens in newly diagnosed patients aged 18-65 with AML/high risk MDS, i.e., idarubicine-cytarabine (cycle I) and amsacrine-cytarabine (cycle II) without or with clofarabine (10 mg/m(2) on days 1-5 of each of both cycles). Consolidation involved chemotherapy with or without hematopoietic stem cell transplantation...

The binding interaction between clofarabine, an important anticancer drug and two important carrier proteins found abundantly in human plasma, Human Serum Albumin (HSA) and α-1 acid glycoprotein (AAG) was investigated by spectroscopic and molecular modeling methods. The results obtained from fluorescence quenching experiments demonstrated that the fluorescence intensity of HSA and AAG is quenched by clofarabine and the static mode of fluorescence quenching is operative. UV-vis spectroscopy deciphered the formation of ground state complex between anticancer drug and the two studied proteins...

We investigated the long-term safety and disease control data obtained with i.v. busulfan (Bu) combined with clofarabine (Clo) in patients with acute lymphoblastic leukemia (ALL) undergoing allogeneic hematopoietic stem cell transplantation (HSCT). A total of 107 patients, median age 38 years (range, 19 to 64 years) received a matched sibling donor (n = 52) or matched unrelated donor (n = 55) transplant for ALL in first complete remission (n = 62), second complete remission (n = 28), or more advanced disease (n = 17)...