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

Advance of structural modification of nucleosides scaffold

With Remdesivir being approved by FDA as a drug for the treatment of Corona Virus Disease 2019 (COVID-19), nucleoside drugs have once again received widespread attention in the medical community. Herein, we summarized modification of traditional nucleoside framework (sugar + base), traizole nucleosides, nucleoside analogues assembled by other drugs, macromolecule-modified nucleosides, and their bioactivity rules. 2'-"Ara"-substituted by -F or -CN group, and 3'-"ara" substituted by acetylenyl group can greatly influence their anti-tumor activities. Dideoxy dehydrogenation of 2',3'-sites can enhance antiviral efficiencies. Acyclic nucleosides and L-type nucleosides mainly represented antiviral capabilities. 5-F Substituted uracil analogues exihibit anti-tumor effects, and the substrates substituted by -I, -CF3, bromovinyl group usually show antiviral activities. The sugar coupled with 1-N of triazolid usually displays anti-tumor efficiencies, while the sugar coupled with 2-N of triazolid mainly represents antiviral activities. The nucleoside analogues assembled by cholesterol, polyethylene glycol, fatty acid and phospholipid would improve their bioavailabilities and bioactivities, or reduce their toxicities.

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.

Novel dodecyl-containing azido and glucuronamide-based nucleosides exhibiting anticancer potential

The synthesis and anticancer evaluation of new series of nucleosides constructed on 5/6-azidoglycosyl or glucuronamide moieties and containing an O- or an N-dodecyl chain, respectively, are disclosed. Based on our previous results, their structures were planned to preclude them to act via a similar metabolic pathway than that of clinically used nucleoside antimetabolites, against which cancer cells frequently acquire resistance. Xylo and gluco-configured 5/6-azido-1,2-di-O-acetyl furanosyl and pyranosyl donors containing a 3-O-dodecyl group were synthesized from diacetone-d-glucose and were subsequently coupled with silylated uracil or 2-acetamido-6-chloropurine. N-Dodecyl glucuronamide-based nucleosides were accessed from acetonide-protected glucofuranurono-6,3-lactone, which was converted in few steps into O-benzylated 1,2-di-O-acetyl furanuronamide or pyranuronamide derivatives to undergo further N-glycosylation. Both types of nucleosides demonstrated notorious antiproliferative effects in chronic myeloid leukemia (K562) and in breast cancer (MCF-7) cells. The most potent molecules were a 6ʹ-azidoglucopyranosyl N7-linked purine nucleoside and glucofuranuronamide derivatives comprising N1-linked uracil and N7-linked purine units with activities in the single-digit micromolar order of concentration against both cell lines. Their GI50 values in MCF-7 cells were similar or ca. 3-fold lower than that of the standard drug 5-fluorouracil. Cell cycle studies and immunoblotting analysis of apoptosis-associated proteins in treated K562 cells indicated that the antiproliferative effect of the most effective nucleosides is based on apoptosis induction.

Nanomedicines for the treatment of hematological malignancies

Hematological malignancies (HM) are a collection of malignant transformations originating from cells in the primary or secondary lymphoid organs. Leukemia, lymphoma, and multiple myeloma comprise the three major types of HM. Current treatment consists of bone marrow transplantation, radiotherapy, immunotherapy and chemotherapy. Although, many chemotherapeutic drugs are clinically available for the treatment of HM, the use of these agents is limited due to dose-related toxicity and lack of specificity to tumor tissue. Moreover, the poor pharmacokinetic profile of most of the chemotherapeutics requires high dosage and frequent administration to maintain therapeutic levels at the target site, both increasing adverse effects. This underlines an urgent need for a suitable drug delivery system to improve efficacy, safety, and pharmacokinetic properties of conventional therapeutics. Nanomedicines have proven to enhance these properties for anticancer therapeutics. The most extensively studied nanomedicine systems are lipid-based nanoparticles and polymeric nanoparticles. Typically, nanomedicines are small sub-micron sized particles in the size range of 20-200 nm. The biocompatible and biodegradable nature of nanomedicines makes them attractive vehicles to improve drug delivery. Their small size allows them to extravasate and accumulate at malignant sites passively by means of the enhanced permeability and retention (EPR) effect, resulting from rapid angiogenesis and inflammation. Moreover, the specificity to the target tissue can be further enhanced by surface modification of nanoparticles. This review describes currently available therapies as well as limitations and potential advantages of nanomedicine formulations for treatment of various types of HM. Additionally, recent investigational and approved nanomedicine formulations and their limited applications in HM are discussed.

Exploitation of new structurally diverse d-glucuronamide-containing N-glycosyl compounds: synthesis and anticancer potential

The synthesis and anticancer evaluation of novel N-glycosyl derivatives containing N-substituted glucuronamide moieties, as nucleoside analogs or as prospective mimetics of glycosyl phosphates or of nucleotides, is reported. These compounds comprise N-anomerically-linked nucleobases or motifs that are surrogates of a phosphate group, such as sulfonamide or phosphoramidate moieties. 1-Sulfonamido glucuronamides containing N-benzyl, N-propargyl or N-dodecyl carboxamide units were synthesized through glycosylation of methanesulfonamide with tetra-O-acetyl glucuronamides. 1-Azido glucuronamides were accessed by microwave-assisted reactions of tetra-O-acetyl glucuronamides with TMSN₃ and were further converted into N-glycosylphosphoramidates by treatment with trimethyl phosphite. Potential glucuronamide-based nucleotide mimetics comprising both an anomeric sulfonamide/phosphoramidate group and a benzyltriazolylmethyl amide system at C-5, as nucleobase mimetics, were synthesized via 'click' cycloaddition of N-propargyl glucuronamide derivatives with benzyl azide. N-Dodecyl tetra-O-acetyl glucuronamides were converted into uracil and purine nucleosides via N-glycosylation of the corresponding silylated nucleobases. Biological screening revealed significant antiproliferative activities of the N-dodecyl glucuronamide-containing sulfonamide, phosphoramidate and nucleosides in K562 and MCF-7 cells. The highest effect was exhibited by the N⁹-linked purine nucleoside in the breast cancer cell MCF-7 with a GI₅₀ value similar to that of clinically used 5-fluorouracil. Immunoblotting and cell cycle analysis of K562 cells treated with the most active compound as well as evaluation of the effect of this nucleoside on the activities of caspases 3 and 7 showed induction of apoptosis as the mechanism of cell death.

Facile Fabrication of Tumor Redox-Sensitive Nanoassemblies of Small-Molecule Oleate Prodrug as Potent Chemotherapeutic Nanomedicine

The conjugate of paclitaxel (PTX) and docosahexaenoic acid has entered into clinical trials. However, the most recent clinical outcomes fell short of expectations, due to the extremely slow drug release from the hydrophobic conjugates. Herein, a novel prodrug-based nanoplatform self-assembled by the disulfide bond linked conjugates of PTX and oleic acid for rapid and differential release of PTX in tumor cells is reported. This redox-responsive prodrug-nanosystem demonstrates multiple therapeutic advantages, including one-step facile fabrication, high drug-loading efficiency (56%, w/w), on-demand drug release responding to redox stimuli, as well as favorable cellular uptake and biodistribution. These advantages result in significantly enhanced antitumor efficacy in vivo, with the tumor almost completely disappearing in mice. Such a uniquely engineered prodrug-nanosystem has great potential to be used as potent chemotherapeutic nanomedicine in clinical cancer therapy.

The contributions of the European Medicines Agency and its pediatric committee to the fight against childhood leukemia

Background

Although the diagnosis of childhood leukemia is no longer a death sentence, too many patients still die, more with acute myeloid leukemia than with acute lymphoblastic leukemia. The European Union pediatric legislation was introduced to improve pharmaceutical treatment of children, but some question whether the European Medicines Agency (EMA) approach is helping children with leukemia. Some have even suggested that the decisions of EMA pediatric committee (PDCO) are counterproductive. This study was designed to investigate the impact of PDCO-issued pediatric investigation plans (PIPs) for leukemia drugs.

Methods

All PIPs listed under “oncology” were downloaded from the EMA website. Non-leukemia decisions including misclassifications, waivers (no PIP), and solid tumors were discarded. The leukemia decisions were analyzed, compared to pediatric leukemia trials in the database http://www.clinicaltrials.gov, and discussed in the light of current literature.

Results

The PDCO leukemia decisions demand clinical trials in pediatric leukemia for all new adult drugs without prioritization. However, because leukemia in children is different and much rarer than in adults, these decisions have resulted in proposed studies that are scientifically and ethically questionable. They are also unnecessary, since once promising new compounds are approved for adults, more appropriate, prioritized pediatric leukemia trials are initiated worldwide without PDCO involvement.

Conclusion

EMA/PDCO leukemia PIPs do little to advance the treatment of childhood leukemia. The unintended negative effects of the flawed EMA/PDCO’s standardized requesting of non-prioritized testing of every new adult leukemia drug in children with relapsed or refractory disease expose these children to questionable trials, and could undermine public trust in pediatric clinical research. Institutions, investigators, and ethics committees/institutional review boards need to be skeptical of trials triggered by PDCO. New, better ways to facilitate drug development for pediatric leukemia are needed.

New treatment for acute myelogenous leukemia

INTRODUCTION

Acute myelogenous leukemia (AML) is a genetically heterogeneous disease. Yet current therapy has changed little over the decades and includes the nucleoside analog cytarabine in combination with an anthracycline as primary therapy. With this approach, durable cures occur in the minority of patients. With the recent improved scientific understanding of the underlying genetic and epigenetic aberrations in AML, there is now the potential of individualized and targeted therapeutic approaches for the curative treatment of AML.

AREAS COVERED

The focus of this article is to review the therapeutic potential of many of the novel agents currently under investigation in the treatment of acute myeloid leukemia. The results of pivotal Phase III studies, as well as ongoing Phase II and III studies and selected Phase I studies with impact on the field of AML therapy will be discussed.

EXPERT OPINION

Advances in the scientific knowledge of the various genetic and epigenetic alterations in AML, in conjunction with more effective, rationally designed and/or novel targeted therapeutics, offers a real hope and expectation of improved AML outcomes in the future.