Results of a phase II trial of a combination of oral cytarabine ocfosfate (YNK01) and interferon alpha-2b for the treatment of chronic myelogenous leukemia patients in chronic phase

Oral cytarabine ocfosfate pharmacokinetics and assessment of leukocyte biomarkers in normal dogs

BACKGROUND

Cytosine arabinoside (Ara-C) is a nucleoside analog prodrug utilized for immunomodulatory effects mediated by its active metabolite Ara-CTP. Optimal dosing protocols for immunomodulation in dogs have not been defined. Cytarabine ocfosfate (CO) is a lipophilic prodrug of Ara-C that can be administered PO and provides prolonged serum concentrations of Ara-C.

OBJECTIVES

Provide pharmacokinetic data for orally administered CO and determine accumulation and functional consequences of Ara-CTP within peripheral blood leukocytes.

ANIMALS

Three healthy female hound dogs and 1 healthy male Beagle.

METHODS

Prospective study. Dogs received 200 mg/m2 of CO PO q24h for 7 doses. Serum and cerebrospinal fluid (CSF) CO and Ara-C concentrations were measured by liquid chromatography-tandem mass spectroscopy (LC-MS/MS). Complete blood counts, flow cytometry, and leukocyte activation assays were done up to 21 days. Incorporation of Ara-CTP within leukocyte DNA was determined by LC-MS/MS.

RESULTS

Maximum serum concentration (Cmax ) for Ara-C was 456.1-724.0 ng/mL (1.88-2.98 μM) and terminal half-life was 23.3 to 29.4 hours. Cerebrospinal fluid: serum Ara-C ratios ranged from 0.54 to 1.2. Peripheral blood lymphocyte concentrations remained within the reference range, but proliferation rates poststimulation were decreased at 6 days. Incorporation of Ara-CTP was not saturated and remained >25% of peak concentration at 13 days.

CONCLUSIONS AND CLINICAL IMPORTANCE

Oral CO may produce prolonged serum Ara-C half-lives at concentrations sufficient to induce functional changes in peripheral leukocytes and is associated with prolonged retention of DNA-incorporated Ara-CTP. Application of functional and active metabolite assessment is feasible and may provide more relevant data to determine optimal dosing regimens for Ara-C-based treatments.

Direct and indirect effects of IFN-α2b in malignancy treatment: not only an archer but also an arrow

Interferon-α2b (IFN-α2b) is a highly active cytokine that belongs to the interferon-α (IFN-α) family. IFN-α2b has beneficial antiviral, antitumour, antiparasitic and immunomodulatory activities. Direct and indirect antiproliferative effects of IFN-α2b have been found to occur via multiple pathways, mainly the JAK-STAT pathway, in certain cancers. This article reviews mechanistic studies and clinical trials on IFN-α2b. Potential regulators of the function of IFN-α2b were also reviewed, which could be utilized to relieve the poor response to IFN-α2b. IFN-α2b can function not only by enhancing the systematic immune response but also by directly killing tumour cells. Different parts of JAK-STAT pathway activated by IFN-α2b, such as interferon alpha and beta receptors (IFNARs), Janus kinases (JAKs) and IFN‐stimulated gene factor 3 (ISGF3), might serve as potential target for enhancing the pharmacological action of IFN-α2b. Despite some issues that remain to be solved, based on current evidence, IFN-α2b can inhibit disease progression and improve the survival of patients with certain types of malignant tumours. More efforts should be made to address potential adverse effects and complications.

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.

The Scotland Leukaemia Registry Audit of Incidence, Diagnosis and Clinical Management of New Patients with Chronic Myeloid Leukaemia in 1999 and 2000

The management of CML has recently become increasingly complex. The Scotland Leukaemia Registry (SLR) sent questionnaires to all 26 Scottish haematology units, of which 18 (69%) responded. From January 1999 to December 2000, 64 new cases of CML were identified by the audit (incidence 0.64/100,00/yr), of which 46 were registered with the SLR. At diagnosis, all 18 units combined bone marrow examination with cytogenetics/FISH, but only 13 performed RT-PCR. Of four units that calculated the Hasford Score, only two used it to inform clinical decisions. 52% of patients entered clinical trials, 57% involving imatinib mesylate (IM). Of the 23 patients who were tissue typed, suitable donors were found for 18, 11 sibling, and 7 unrelated, representing 28% of the total patient population. Only 13/64 patients (20%) did not have a BMT donor identified or enter a clinical trial. Although 38% of units would consider reduced intensity allografting in patients > 60 years, no centres currently routinely tissue-type such patients. For first line therapy 56% of patients received hydroxyurea +/- interferon. Of the newer agents, 83% of units believed imatinib mesylate should be reserved for clinical trials, 83% would consider using oral ara-C and 89% pegylated-interferon.

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.

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.

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.

Interferon-alpha-2b and oral cytarabine ocfosfate for newly diagnosed chronic myeloid leukaemia

BACKGROUND

Treatment with interferon and subcutaneous cytarabine produces superior cytogenetic responses in chronic myeloid leukaemia (CML) than treatment with interferon alone, but at the expense of greater toxicity. Cytarabine ocfosfate (YNK01) is an oral precursor of cytarabine that may overcome some of the inconvenience and toxicities associated with subcutaneous cytarabine administration.

PATIENTS AND METHODS

We studied the efficacy and tolerability of combination therapy with interferon-alpha-2b and YNK01 in patients with newly diagnosed, untreated CML. Forty patients were treated with interferon-alpha-2b (5 MU/m2/day) plus monthly courses of YNK01 (600 mg/day for 10 days) for 1 year.

RESULTS

The 6-month complete haematological response rate was 63% and the 1-year major cytogenetic response rate was 30%, with 10% of cytogenetic responses being complete. With a median follow-up of 57 months, the estimated 5-year overall survival was 86% (95% confidence interval 70% to 94%). Treatment tolerability was poor, with toxicity leading to discontinuation of one or both drugs in 60% of cases. The median daily dose of interferon alpha-2b was 7.75 MU and the median dose of YNK01 was 600 mg/day for each 10-day treatment cycle.

CONCLUSIONS

Interferon-alpha-2b and YNK01 produce cytogenetic responses comparable to those achieved with interferon-alpha-2b and parenteral cytarabine, although toxicity was excessive. Alternate dosing strategies may enhance the tolerability of YNK01.

Interferon therapy in chronic myelogenous leukemia

Interferon (IFN)-alpha, the molecule used in the treatment of chronic myelogenous leukemia and initially prepared from human leucocytes,is now produced essentially by recombinant techniques. Polyethylene glycol (PEG) modifications of proteins could be more effective than the regular molecules; thus, pegylated IFNs more recently have been tested in chronic myelogenous leukemia. PEG modification of proteins reduces sensitivity to proteolysis. Moreover,administration of pegylated IFNs results in less antigenicity and immunogenicity, and prolongation of their plasma half-life has been assessed by pharmacokinetic studies. It is assumed, therefore, that this compound could be more effective and better tolerated. Given the results recently obtained with imatinib, however, whether IFN-alpha will still have a therapeutic role is questionable.

Results of a prospective phase 2 study combining imatinib mesylate and cytarabine for the treatment of Philadelphia-positive patients with chronic myelogenous leukemia in chronic phase

In chronic myelogenous leukemia (CML) imatinib mesylate has been shown to selectively inhibit the tyrosine kinase domain of the oncogenic bcr-abl fusion protein. Using this agent alone high rates of cytogenetic responses were recorded. However, several mechanisms of resistance have been described. In vitro studies examining the effects of imatinib mesylate plus cytarabine have shown synergistic antiproliferative effects of this combination. Thus, the CML French Group decided to perform a phase 2 trial testing a combination of imatinib mesylate and low-dose cytarabine in 30 previously untreated patients in chronic phase. Treatment was administered on 28-day cycles. Patients were treated continuously with imatinib mesylate orally at a dose of 400 mg daily. Cytarabine was given on days 15 to 28 of each cycle at an initial dose of 20 mg/m2/d via subcutaneous injection. Adverse events were frequently observed with grade 3 or 4 hematologic toxicities and nonhematologic toxicities in 53% (n = 16) and 23% (n = 7) of patients, respectively. The cumulative incidence of complete cytogenetic response (CCR) at 12 months was 83% and at 6 months 100% of the patients achieved complete hematologic response (CHR). We concluded that the combination was safe and promising given the rates of response.

Chronic myelogenous leukemia as a paradigm of early cancer and possible curative strategies

The chronological history of the important discoveries leading to our present understanding of the essential clinical, biological, biochemical, and molecular features of chronic myelogenous leukemia (CML) are first reviewed, focusing in particular on abnormalities that are responsible for the massive myeloid expansion. CML is an excellent target for the development of selective treatment because of its highly consistent genetic abnormality and qualitatively different fusion gene product, p210(bcr-abl). It is likely that the multiple signaling pathways dysregulated by p210(bcr-abl) are sufficient to explain all the initial manifestations of the chronic phase of the disease, although understanding of the circuitry is still very incomplete. Evidence is presented that the signaling pathways that are constitutively activated in CML stem cells and primitive progenitors cooperate with cytokines to increase the proportion of stem cells that are activated and thereby increase recruitment into the committed progenitor cell pool, and that this increased activation is probably the primary cause of the massive myeloid expansion in CML. The cooperative interactions between Bcr-Abl and cytokine-activated pathways interfere with the synergistic interactions between multiple cytokines that are normally required for the activation of stem cells, while at the same time causing numerous subtle biochemical and functional abnormalities in the later progenitors and precursor cells. The committed CML progenitors have discordant maturation and reduced proliferative capacity compared to normal committed progenitors, and like them, are destined to die after a limited number of divisions. Thus, the primary goal of any curative strategy must be to eliminate all Philadelphia positive (Ph+) primitive cells that are capable of symmetric division and thereby able to expand the Ph+ stem cell pool and recreate the disease. Several highly potent and moderately selective inhibitors of Bcr-Abl kinase have recently been discovered that are capable of killing the majority of actively proliferating early CML progenitors with minimal effects on normal progenitors. However, like their normal counterparts, most of the CML primitive stem cells are quiescent at any given time and are relatively invulnerable to the Bcr-Abl kinase inhibitors as well as other drugs. We propose that survival of dormant Ph+ stem cells may be the most important reason for the inability to cure the disease during initial treatment, while resistance to the inhibitors and other drugs becomes increasingly important later. An outline of a possible curative strategy is presented that attempts to take advantage of the subtle differences in the proliferative behavior of normal and Ph+ stem cells and the newly discovered selective inhibitors of Bcr-Abl. Leukemia (2003) 17, 1211-1262. doi:10.1038/sj.leu.2402912

Imatinib in combination with cytarabine for the treatment of Philadelphia-positive chronic myelogenous leukemia chronic-phase patients: rationale and design of phase I/II trials

Imatinib (Gleevec) (formerly STI571) has been shown to selectively inhibit the tyrosine kinase domain of the oncogenic BCR-ABL fusion protein of chronic myelogenous leukemia (CML) cells. In recent phase I and II studies testing this new compound in patients who had failed to respond to interferon (IFN), hematological and cytogenetic responses were reported in most of those with chronic-phase CML. However, in some patients resistance has been associated with a single amino acid substitution in a threonine residue of the Abl kinase domain. In vitro studies examining the effects of imatinib plus cytarabine (Ara-C) using CML cell lines and colony-forming assays of CML patient samples have shown synergistic antiproliferative effects of this combination. Thus several groups decided to investigate this new combination with the hypothesis that cell resistance would be less frequent. The CML French Group performed a phase II trial to determine the safety and tolerability of a combination of imatinib and Ara-C for previously untreated patients with chronic-phase CML. Treatment was administered on 28-day cycles for 12 months. Patients were treated continuously with imatinib orally at a dose of 400 mg daily. Ara-C was given on days 14 to 28 of each cycle at an initial dose of 20 mg/m(2)/d via subcutaneous injection, hydroxyurea (HU) being stopped at least 7 days before imatinib. Recently, the Dutch group decided to explore a combination of high-dose Ara-C with imatinib in patients in chronic-phase CML. Preliminary results are encouraging. However, a long follow-up is required before concluding that these strategies will overcome cell resistance.

A phase II study of alpha-interferon and oral arabinosyl cytosine (YNK01) in chronic myeloid leukemia

YNK01 (Starasid) is a prodrug that is adsorbed in the gut and is transformed in the liver in arabinosyl cytosine (AC). Low-dose AC (LDAC) is useful for the treatment of Philadelphia positive (Ph+) chronic myeloid leukemia (CML), especially in combination with alpha-interferon (alphaIFN). The use of YNK01 can avoid the daily s.c. injection of conventional AC. To assess the safety and the efficacy of alphaIFN and YNK01, we enrolled 86 consecutive previously untreated chronic phase Ph+ CML patients in a phase II study of alphaIFN (Intron-A) 5 MIU/m(2) daily and YNK01 600 mg daily 14 days a month. The 6-month complete hematologic response and the 12-month major cytogenetic response rates were 78 and 28%, respectively. In a prior study of alphaIFN and conventional LDAC, they were 62 and 22%, respectively. However, the compliance to the treatment was poor, with 25% of cases discontinuing the treatment within the first year. This was not because of the severity of the side effects but because of the frequency, duration and repetition of the side effects, for an overall frequency of 13.17 adverse events, mostly grade 1 and 2, per patient per year. Therefore, the study of this effective combination is being pursued, testing lower doses of alphaIFN and YNK01.

[Interferons and hematology]

BACKGROUND

IFN alpha are cytokines used for a number of years in the treatment of certain hemopathies, i.e. of a myeloid and lymphoid etiology. IFN alpha are a family of polypeptides produced by eukaryote cells in response to various stimulant agents. The first trials using this cytokine in humans were carried out by H. Strander in the years 1965-1970. IFN alpha contain anti-viral, anti-proliferative and immunomodulatory properties. The access of clinicians to IFN alpha molecules, in addition to elements produced by genetic engineering for approximately the past 20 years, has permitted a number of therapeutic trials to be carried out. In hematology the clinical interest of IFN alpha was primarily in chronic myeloid and lymphoid proliferating syndromes. Certain indications have to date been well demonstrated. However, the impact of IFN alpha on therapeutic care of certain hemopathies as compared to conventional treatment remains controversial. At the same time, the frequency of side effects from treatment with IFN alpha and its cost should be taken into consideration.

CURRENT POSITION AND MAJOR POINTS

The therapeutic trials carried out over the past ten years have proven the interest of IFN alpha in, essentially, two diseases: on one hand chronic myeloid leukemia with the acquisition of cytogenetic remission and on the other malignant non-Hodgkin's follicular type lymphoma. However, as regards other hemopathies the place of IFN alpha remains debatable.

PERSPECTIVES

The future of IFN alpha use in the treatment of hemopathies appears to be linked to its association with new treatments, an association, however, where its efficacy and superiority should be demonstrated. This is the case in chronic myeloid leukemia where IFN alpha could be associated with aracytine or the inhibitors of tyrosine kinase. Also, in the treatment of malignant non-Hodgkin's lymphomas as well as the studies concerning the association between IFN alpha and monoclonal antibodies, in particular antibody anti-CD 20.