Elacytarabine has single-agent activity in patients with advanced acute myeloid leukaemia

Hyponatremia in Patients with Hematologic Diseases

Hyponatremia is the most common electrolyte disorder in clinical practice and is associated with increased morbidity and mortality. It is frequently encountered in hematologic patients with either benign or malignant diseases. Several underlying mechanisms, such as hypovolemia, infections, toxins, renal, endocrine, cardiac, and liver disorders, as well as the use of certain drugs appear to be involved in the development or the persistence of hyponatremia. This review describes the pathophysiology of hyponatremia and discusses thoroughly the contributing factors and mechanisms that may be encountered specifically in patients with hematologic disorders. The involvement of the syndrome of inappropriate antidiuretic hormone (SIADH) secretion and renal salt wasting syndrome (RSWS) in the development of hyponatremia in such patients, as well as their differential diagnosis and management, are also presented. Furthermore, the distinction between true hyponatremia and pseudohyponatremia is explained. Finally, a practical algorithm for the evaluation of hyponatremia in hematologic patients, as well as the principles of hyponatremia management, are included in this review.

Emerging insights on drug delivery by fatty acid mediated synthesis of lipophilic prodrugs as novel nanomedicines

Many drug molecules that are currently in the market suffer from short half-life, poor absorption, low specificity, rapid degradation, and resistance development. The design and development of lipophilic prodrugs can provide numerous benefits to overcome these challenges. Fatty acids (FAs), which are lipophilic biomolecules constituted of essential components of the living cells, carry out many necessary functions required for the development of efficient prodrugs. Chemical conjugation of FAs to drug molecules may change their pharmacodynamics/pharmacokinetics in vivo and even their toxicity profile. Well-designed FA-based prodrugs can also present other benefits, such as improved oral bioavailability, promoted tumor targeting efficiency, controlled drug release, and enhanced cellular penetration, leading to improved therapeutic efficacy. In this review, we discuss diverse drug molecules conjugated to various unsaturated FAs. Furthermore, various drug-FA conjugates loaded into various nanostructure delivery systems, including liposomes, solid lipid nanoparticles, emulsions, nano-assemblies, micelles, and polymeric nanoparticles, are reviewed. The present review aims to inspire readers to explore new avenues in prodrug design based on the various FAs with or without nanostructured delivery systems.

The Novel Phospholipid Mimetic KPC34 Is Highly Active Against Acute Myeloid Leukemia with Activated Protein Kinase C

Acute myeloid leukemia (AML) is an aggressive malignancy with poor outcomes. Nucleoside analogs are subject to resistance mechanisms including downregulation of equilibrative nucleoside transporter (ENT1) and deoxycytidine kinase (dCK). KPC34 is a novel phospholipid mimetic that when cleaved by phospholipase C (PLC) liberates gemcitabine monophosphate and a diacylglycerol mimetic that inhibits the classical isoforms of protein kinase C (PKC). KPC34 acts independently of ENT1 and dCK. KPC34 was active against all AML cell lines tested with IC₅₀s in the nanomolar range. Enforced expression of PLC increased response to KPC34 in vivo. In an orthotopic, xenograft model, KPC34 treatment resulted in a significant increase in survival compared to control animals and those treated with high-dose cytarabine. In a PDX model with activated PKC, there was a significant survival benefit with KPC34, and at progression, there was attenuation of PKC activation in the resistant cells. In contrast, KPC34 was ineffective against a syngeneic, orthotopic AML model without activated PKC. However, when cells from that model were forced to express PKC, there were significantly increased sensitivity in vitro and survival benefit in vivo. These data suggest that KPC34 is active against AML and that the presence of activated PKC can be a predictive biomarker.

Electrolyte Disorders Induced by Antineoplastic Drugs

The use of antineoplastic drugs has a central role in treatment of patients affected by cancer but is often associated with numerous electrolyte derangements which, in many cases, could represent life-threatening conditions. In fact, while several anti-cancer agents can interfere with kidney function leading to acute kidney injury, proteinuria, and hypertension, in many cases alterations of electrolyte tubular handling and water balance occur. This review summarizes the mechanisms underlying the disturbances of sodium, potassium, magnesium, calcium, and phosphate metabolism during anti-cancer treatment. Platinum compounds are associated with sodium, potassium, and magnesium derangements while alkylating agents and Vinca alkaloids with hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion (SIADH). Novel anti-neoplastic agents, such as targeted therapies (monoclonal antibodies, tyrosine kinase inhibitors, immunomodulators, mammalian target of rapamycin), can induce SIADH-related hyponatremia and, less frequently, urinary sodium loss. The blockade of epidermal growth factor receptor (EGFR) by anti-EGFR antibodies can result in clinically significant magnesium and potassium losses. Finally, the tumor lysis syndrome is associated with hyperphosphatemia, hypocalcemia and hyperkalemia, all of which represent serious complications of chemotherapy. Thus, clinicians should be aware of these side effects of antineoplastic drugs, in order to set out preventive measures and start appropriate treatments.

Phase 1/2 study of DFP-10917 administered by continuous intravenous infusion in patients with recurrent or refractory acute myeloid leukemia

BACKGROUND

DFP-10917, a deoxycytidine nucleoside analogue, has a unique mechanism of action resulting in leukemic cell death when administered for prolonged periods at low doses. The current phase 1/2 study investigated the safety, maximum tolerated dose, and evidence of antileukemic activity for DFP-10917 administered by 7-day or 14-day continuous intravenous infusion in patients with recurrent or refractory acute myeloid leukemia (AML).

METHODS

In the phase 1 dose escalation portion of the study, patients were administered DFP-10917 by 7-day continuous intravenous infusion plus 21-day rest (stage 1) or 14-day continuous intravenous infusion plus 14-day rest (stage 2). The primary objectives of phase 1 were to determine the maximum tolerated dose, the phase 2 dose, and the dose-limiting toxicities (DLTs) of DFP-10917. The primary objectives of phase 2 were to evaluate the overall response rate of DFP-10917 using complete response (CR), CR without platelet recovery (CRp), CR with incomplete blood count recovery (CRi) or partial response.

RESULTS

In stage 1 of phase 1 (4-35 mg/m² /day as a 7-day continuous intravenous infusion), a DLT of grade 3 diarrhea occurred at a dose of 35 mg/m² /day. In stage 2 of phase 1, a dose of 10 mg/m² /day as a 14-day continuous intravenous infusion resulted in DLTs of prolonged hypocellularity, abdominal pain, diarrhea, and vomiting. The dose of 6 mg/m² /day as a 14-day continuous intravenous infusion was found to be well tolerated and was selected for phase 2. Response rates in patients in phase 2 (N = 29) were 20.7% CR, 3.4% CRp, and 24.1% CRi. The overall response rate was 48.3% (95% confidence interval, 29.4%-67.5%).

CONCLUSIONS

DFP-10917 as a 14-day continuous intravenous infusion at a dose of 6 mg/m² /day can be administered safely and appears to be effective in patients with recurrent or refractory AML. A phase 3 investigation comparing DFP-10917 monotherapy versus standard of care in an early recurrent or refractory AML setting is warranted.

Metabolism, Biochemical Actions, and Chemical Synthesis of Anticancer Nucleosides, Nucleotides, and Base Analogs

Nucleoside, nucleotide, and base analogs have been in the clinic for decades to treat both viral pathogens and neoplasms. More than 20% of patients on anticancer chemotherapy have been treated with one or more of these analogs. This review focuses on the chemical synthesis and biology of anticancer nucleoside, nucleotide, and base analogs that are FDA-approved and in clinical development since 2000. We highlight the cellular biology and clinical biology of analogs, drug resistance mechanisms, and compound specificity towards different cancer types. Furthermore, we explore analog syntheses as well as improved and scale-up syntheses. We conclude with a discussion on what might lie ahead for medicinal chemists, biologists, and physicians as they try to improve analog efficacy through prodrug strategies and drug combinations.

Considerations and challenges for patients with refractory and relapsed acute myeloid leukaemia

Despite advances in understanding the complexities of acute myeloid leukaemia (AML), the treatment of refractory or relapsed AML (rrAML) remains a daunting clinical challenge. Numerous clinical trials have failed to identify new treatments or combinations of existing therapies that substantially improve outcomes and survival. This may be due, at least in part, to heterogeneity among study patients with respect to multiple inter-related factors that have been shown to affect treatment outcomes for patients with rrAML; such factors include age, cytogenetics, immunophenotypic changes, and (in the case of relapsed AML) duration of first complete remission, or if the patient has had a previous blood and marrow transplant (BMT). A clear understanding of disease characteristics and patient-related factors that influence treatment response, as well as expected outcomes with existing and emerging therapies, can aid clinicians in helping their patients navigate through this complex disease state.

Electrolyte disorders associated with the use of anticancer drugs

The use of anticancer drugs is beneficial for patients with malignancies but is frequently associated with the occurrence of electrolyte disorders, which can be hazardous and in many cases fatal. The review presents the electrolyte abnormalities that can occur with the use of anticancer drugs and provides the related mechanisms. Platinum-containing anticancer drugs induce hypomagnesemia, hypokalemia and hypocalcemia. Moreover, platinum-containing drugs are associated with hyponatremia, especially when combined with large volumes of hypotonic fluids aiming to prevent nephrotoxicity. Alkylating agents have been linked with the occurrence of hyponatremia [due to syndrome of inappropriate antidiuretic hormone secretion (SIADH)] and Fanconi's syndrome (hypophosphatemia, aminoaciduria, hypouricemia and/or glucosuria). Vinca alkaloids are associated with hyponatremia due to SIADH. Epidermal growth factor receptor monoclonal antibody inhibitors induce hypomagnesemia, hypokalemia and hypocalcemia. Other, monoclonal antibodies, such as cixutumumab, cause hyponatremia due to SIADH. Tyrosine kinase inhibitors are linked to hyponatremia and hypophosphatemia. Mammalian target of rapamycin inhibitors induce hyponatremia (due to aldosterone resistance), hypokalemia and hypophosphatemia. Other drugs such as immunomodulators or methotrexate have been also associated with hyponatremia. The administration of estrogens at high doses, streptozocin, azacitidine and suramin may induce hypophosphatemia. Finally, the drug-related tumor lysis syndrome is associated with hyperphosphatemia, hyperkalemia and hypocalcemia. The prevention of electrolyte derangements may lead to reduction of adverse events during the administration of anticancer drugs.

Improving nucleoside analogs via lipid conjugation: Is fatter any better?

In the past few decades, nucleoside analog drugs have been used to treat a large variety of cancers. These anti-metabolite drugs mimic nucleosides and interfere with chain lengthening upon incorporation into the DNA or RNA of actively replicating cells. However, efficient delivery of these drugs is limited due to their pharmacokinetic properties, and tumors often develop drug resistance. In addition, nucleoside analogs are generally hydrophilic, resulting in poor bioavailability and impaired blood-brain barrier penetration. Conjugating these drugs to lipids modifies their pharmacokinetic properties and may improve in vivo efficacy. This review will cover recent advances in the field of conjugation of phospholipids to nucleoside analogs. This includes conjugation of myristic acid, 12-thioethyldodecanoic acid, 5-elaidic acid esters, phosphoramidate, and self-emulsifying formulations. Relevant in vitro and in vivo data will be discussed for each drug, as well as any available data from clinical trials.

Clinical potential of elacytarabine in patients with acute myeloid leukemia

Acute myeloid leukemia (AML) has been treated for over four decades with standard induction chemotherapy including seven days of cytosine arabinoside (cytarabine, ara-C) infusion. Cytarabine, while effective in killing leukemic cells, is subject to development of several resistance mechanisms rendering the drug ineffective in many patients. Elacytarabine, a lipophilic 5'-elaidic acid ester or nucleoside analogue of cytosine arabinoside, was created with the intent of overcoming resistance mechanisms including reduced expression of the human equilibrative nucleoside transporter 1 (hENT1) required for cytarabine entry into cells, as well as increased activity of cytidine deaminase (CDA) which breaks down the active metabolite of cytarabine, ara-CTP. Elacytarabine enters cells independently of transporters, has a longer half life compared with cytarabine and is not subject to deactivation by CDA. Preclinical data were encouraging although subsequent clinical studies have failed to show superiority of elacytarabine compared with standard of care as monotherapy in patients with AML. Clinical trials utilizing elacytarabine in combination with anthracyclines are ongoing. Use of hENT1 expression as a predictive marker for cytarabine or elacytarabine response has been studied with no conclusive validation to date. Despite promising early results, the jury is still out in regards to this novel agent as an effective alternative to standard cytarabine therapy in acute leukemias, especially in combination with additional agents such as anthracyclines.

International Randomized Phase III Study of Elacytarabine Versus Investigator Choice in Patients With Relapsed/Refractory Acute Myeloid Leukemia

Purpose

Most patients with acute myeloid leukemia (AML) eventually experience relapse. Relapsed/refractory AML has a dismal prognosis and currently available treatment options are generally ineffective. The objective of this large, international, randomized clinical trial was to investigate the efficacy of elacytarabine, a novel elaidic acid ester of cytarabine, versus the investigator's choice of one of seven commonly used AML salvage regimens, including high-dose cytarabine, multiagent chemotherapy, hypomethylating agents, hydroxyurea, and supportive care.

Patients and Methods

A total of 381 patients with relapsed/refractory AML were treated in North America, Europe, and Australia. Investigators selected a control treatment for individual patients before random assignment. The primary end point was overall survival (OS).

Results

There were no significant differences in OS (3.5 v 3.3 months), response rate (23% v 21%), or relapse-free survival (5.1 v 3.7 months) between the elacytarabine and control arms, respectively. There was no significant difference in OS among any of the investigator's choice regimens. Prolonged survival was only achieved in a few patients in both study arms whose disease responded and who underwent allogeneic stem-cell transplantation.

Conclusion

Neither elacytarabine nor any of the seven alternative treatment regimens provided clinically meaningful benefit to these patients. OS in both study arms and for all treatments was extremely poor. Novel agents, novel clinical trial designs, and novel strategies of drug development are all desperately needed for this patient population.

Elacytarabine in relapsed/refractory acute myeloid leukaemia: an evaluation of clinical efficacy, pharmacokinetics, cardiac safety and effects on lipid profile

Elacytarabine is the elaidic acid ester derivative of cytarabine, designed to enter cells independently of nucleoside transporters. Effects of elacytarabine on QT interval, serum lipid profile and clinical activity were investigated in 43 relapsed/refractory AML patients. Mean maximum increase in corrected QT interval of 24( ± 29)ms occurred 48 h after elacytarabine infusion without associated arrhythmias or clinical symptoms. A non-clinically significant, elacytarabine exposure-dependent increase in cholesterol was caused by a cholesterol rich lipoprotein depleted of apolipoprotein B formed by infused phospholipids complexing cholesterol. Elacytarabine is clinically active in relapsed/refractory AML: overall response rate (CR + CRi) was 44% (16/36 with 7 non-evaluable patients) and adverse events were manageable. Clinical Trials.gov Identifier: NCT01258816.

Developmental therapeutics in acute myelogenous leukemia: are there any new effective cytotoxic chemotherapeutic agents out there?

Therapies for AML have remained mostly unchanged since the introduction of anthracyline- and cytarabine-based regimens in the 1970s. Though some changes have been made in the dosing of anthracylines, in the choice of consolidation regimens versus allogeneic stem cell transplant, and in supportive care, clinical outcomes remain poor for most patients. As we continue to strive for better treatment options to improve upon outcomes, different agents, both chemotherapeutic and targeted therapies, are being studied. Here we discuss new chemotherapeutic agents that show promise in recent clinical trials and attempt to answer the question if there are any new effective cytotoxic chemotherapy agents out there.

Elacytarabine (CP-4055) in the treatment of acute myeloid leukemia

Elacytarabine (formerly CP-4055) is a lipid-conjugated derivative of the nucleoside analog cytarabine. Elacytarabine was rationally designed to circumvent cytarabine resistance related to decreased cellular uptake, due to the ability of the lipophilic drug moiety to enter the cell without the requirement of specialized nuclear transport proteins, including the hENT1. In preclinical and clinical studies, elacytarabine has demonstrated both safety and efficacy in acute myeloid leukemia (AML), with noteworthy activity among the cytarabine-refractory AML population. Elacytarabine was granted orphan drug designation status from the European Commission in 2007 and from the US FDA in 2008, with a fast-track approval designation from the FDA in 2010. Results of a recent randomized Phase III clinical trial, however, failed to show superiority of elacytarabine over the investigator's choice of therapy for relapsed or refractory AML.

Advances in the development of nucleoside and nucleotide analogues for cancer and viral diseases

Nucleoside analogues have been in clinical use for almost 50 years and have become cornerstones of treatment for patients with cancer or viral infections. The approval of several additional drugs over the past decade demonstrates that this family still possesses strong potential. Here, we review new nucleoside analogues and associated compounds that are currently in preclinical or clinical development for the treatment of cancer and viral infections, and that aim to provide increased response rates and reduced side effects. We also highlight the different approaches used in the development of these drugs and the potential of personalized therapy.

The thorny issue of relapsed acute myeloid leukemia

PURPOSE OF REVIEW

Acute myeloid leukemia (AML) is a devastating disease, in which the majority of afflicted patients eventually experience relapse and die from their disease.

RECENT FINDINGS

Clinical and molecular characterization of the disease have greatly aided in prognostication in both primary and relapsed settings, which may broadly guide therapy, but truly effective standards of care for relapsed AML remain lacking. Traditional chemotherapeutic drugs have modest but limited efficacy in relapsed AML, whereas more novel and potent cytotoxic chemotherapeutic agents hold promise and are entering the advanced phases of testing. Targeted therapies for AML have demonstrated activity, often as single agents, generating enthusiasm for further development in subgroups of patients with appropriate molecular anomalies. Finally, allogeneic stem cell transplantation continues to evolve as an effective and potentially curative therapy for limited numbers of patients with relapsed AML.

SUMMARY

The complexity of relapsed AML will dictate the need for continued development of novel chemotherapeutic and targeted therapies that suit the molecular and clinical profiling of individual patients.

Advances in the development of nucleoside and nucleotide analogues for cancer and viral diseases

Nucleoside analogues have been in clinical use for almost 50 years and have become cornerstones of treatment for patients with cancer or viral infections. The approval of several additional drugs over the past decade demonstrates that this family still possesses strong potential. Here, we review new nucleoside analogues and associated compounds that are currently in preclinical or clinical development for the treatment of cancer and viral infections, and that aim to provide increased response rates and reduced side effects. We also highlight the different approaches used in the development of these drugs and the potential of personalized therapy.

High-risk acute myelogenous leukemia: treatment today ... and tomorrow

High-risk acute myelogenous leukemia (AML) constitutes a distinct subset of disease based on clinical and biological characteristics and comprises a significant percentage of all cases of adult AML. Biologic features such as distinct clonal cytogenetic and molecular abnormalities identify a subgroup of AML patients characterized by poor response to induction chemotherapy and poor long-term survival after treatment with consolidation chemotherapy. Clinical variables that predict for poor response include AML relapsed after less than 1 year of remission and AML characterized by resistance to conventional agents. We review here our understanding of the defining biologic subtypes of AML and discuss how adequate initial evaluation can be used to inform the choice of treatment. By defining high-risk biologic and clinical variables, a strong case can be made for treating patients with investigational agents, with treatment directed at distinct cytogenetic or molecular abnormalities. Allogeneic transplantation is the only form of therapy available outside of the setting of a clinical trial that may offer a chance for long-term survival for patients with high-risk AML.