Review of Transporter Substrate, Inhibitor, and Inducer Characteristics of Cladribine

Nucleoside-based anticancer drugs: Mechanism of action and drug resistance

Nucleoside-based drugs, recognized as purine or pyrimidine analogs, have been potent therapeutic agents since their introduction in 1950, deployed widely in the treatment of diverse diseases such as cancers, myelodysplastic syndromes, multiple sclerosis, and viral infections. These antimetabolites establish complex interactions with cellular molecular constituents, primarily via activation of phosphorylation cascades leading to consequential interactions with nucleic acids. However, the therapeutic efficacy of these agents is frequently compromised by the development of drug resistance, a continually emerging challenge in their clinical application. This comprehensive review explores the mechanisms of resistance to nucleoside-based drugs, encompassing a wide spectrum of phenomena from alterations in membrane transporters and activating kinases to changes in drug elimination strategies and DNA damage repair mechanisms. The critical analysis in this review underlines complex interactions of drug and cell and also guides towards novel therapeutic strategies to counteract resistance. The development of targeted therapies, novel nucleoside analogs, and synergistic drug combinations are promising approaches to restore tumor sensitivity and improve patient outcomes.

Combined analysis of bulk and single-cell RNA sequencing reveals novel natural killer cell-related prognostic biomarkers for predicting immunotherapeutic response in hepatocellular carcinoma

Introduction

Natural killer (NK) cells play an irreplaceable and important role as a subtype of innate immune cells in the contemporary setting of antitumor immunity.

Methods

We chose a total of 1,196 samples for this analysis from the public dataset’s six separate cohorts. To identify 42 NK cell marker genes, we first carried out a thorough study of single-cell RNA sequencing data from the GSE149614 cohort of hepatocellular carcinoma (HCC).

Results

Using the NK cell marker genes in the TCGA cohort, we next created a seven-gene prognostic signature, separating the patients into two categories with distinct survival patterns. This signature’s prognostic prediction ability was well verified across several validation cohorts. Patients with high scores had higher TIDE scores but lower immune cell infiltration percentages. Importantly, low-scoring patients had superior immunotherapy response and prognosis than high-scoring patients in an independent immunotherapy cohort (IMvigor210). Finally, we used CD56 and TUBA1B antibodies for immunohistochemical labeling of HCC tissue sections, and we discovered a lower number of CD56+ cells in the HCC tissue sections with high TUBA1B expression.

Discussion

In summary, our research created a unique prognostic profile based on NK cell marker genes that may accurately predict how well immunotherapy would work for HCC patients.

Cladribine treatment for highly active multiple sclerosis: Real-world clinical outcomes for years 3 and 4

INTRODUCTION

Cladribine is an effective immunomodulatory treatment used for relapsing forms of multiple sclerosis (MS).

OBJECTIVES

To describe the clinical outcomes and rates of no evidence of disease activity (NEDA) in patients with highly-active disease treated with 2 years cumulative dose of cladribine, for years 3 and 4.

METHODS

We used the Sheba Multiple Sclerosis computerized data registry to retrospectively evaluate year-3 and year-4 clinical outcomes and NEDA-2 rates in highly active RRMS patients who completed the 2-dose 2-year cladribine treatment protocol (3.5 mg/kg cumulative dose over 2 years). The first week of treatment in year 1 was considered as baseline. Data analyses were performed using Python (version 3.0) and SAS® (version 9.4 SAS Institute, Cary, NC).

RESULTS

Among 128 patients with highly-active MS that received cladribine treatment, 61 patients, 43 females, were studied for year-3 clinical outcomes, and 35 patients, 23 females, also for year-4. At the initiation of cladribine treatment, the mean ± SD age was 39.6 ± 10.74 years (45.9% of the patients were between 18 and 40 years), disease duration 12.7 ± 9.08 years, Expanded Disability Status Scale (EDSS) 3.7 ± 1.86 (54% had EDSS score > 3.0), and the annual relapse rate was 1.6 ± 0.9. The annual relapse rate decreased to 0.36 in year-3 and was 0.17 in year-4; 68.9% (42/61) of the patients were relapse-free in year-3, and 82.9% (29/35) were relapse-free in year-4. Disability at year-3 was 3.1 ± 2.07; 83.6% (51/61) of the patients remained neurologically stable (33, 54.1%) or improved (18, 29.5%). In year-4, EDSS was 3.2 ± 1.91, and 85.7% (30/35) of the patients remained stable (20, 57.1%) or improved (10, 28.6%). NEDA-2 was achieved for 59.0% (36/61) of patients in year-3, and for 74.3% (26/35) in year-4 of cladribine treatment.

CONCLUSIONS

In the real-world cladribine proved to be clinically effective in year-3 and year-4 of treatment in the majority of highly active RRMS patients.

Current Chemical, Biological, and Physiological Views in the Development of Successful Brain-Targeted Pharmaceutics

One of the greatest challenges with successful pharmaceutical treatments of central nervous system (CNS) diseases is the delivery of drugs into their target sites with appropriate concentrations. For example, the physically tight blood-brain barrier (BBB) effectively blocks compounds from penetrating into the brain, also by the action of metabolizing enzymes and efflux transport mechanisms. However, many endogenous compounds, including both smaller compounds and macromolecules, like amino acids, sugars, vitamins, nucleosides, hormones, steroids, and electrolytes, have their peculiar internalization routes across the BBB. These delivery mechanisms, namely carrier-mediated transport and receptor-mediated transcytosis have been utilized to some extent in brain-targeted drug development. The incomplete knowledge of the BBB and the smaller than a desirable number of chemical tools have hindered the development of successful brain-targeted pharmaceutics. This review discusses the recent advancements achieved in the field from the point of medicinal chemistry view and discusses how brain drug delivery can be improved in the future.

Cladribine as a Potential Object of Nucleoside Transporter-Based Drug Interactions

Cladribine is a nucleoside analog that is phosphorylated in its target cells (B and T-lymphocytes) to its active triphosphate form (2-chlorodeoxyadenosine triphosphate). Cladribine tablets 10 mg (Mavenclad^®), administered for up to 10 days per year in 2 consecutive years (3.5-mg/kg cumulative dose over 2 years), are used to treat patients with relapsing multiple sclerosis. Cladribine has been shown to be a substrate of various nucleoside transporters (NTs). Intestinal absorption and distribution of cladribine throughout the body appear to be essentially mediated by equilibrative NTs (ENTs) and concentrative NTs (CNTs), specifically by ENT1, ENT2, ENT4, CNT2 (low affinity), and CNT3. Other efficient transporters of cladribine are the ABC efflux transporters, specifically breast cancer resistance protein, which likely modulates the oral absorption and renal excretion of cladribine. A key transporter for the intracellular uptake of cladribine into B and T-lymphocytes is ENT1 with ancillary contributions of ENT2 and CNT2. Transporter-based drug interactions affecting absorption and target cellular uptake of a prodrug such as cladribine are likely to reduce systemic bioavailability and target cell exposure, thereby possibly hampering clinical efficacy. In order to manage optimized therapy, i.e., to ensure uncompromised target cell uptake to preserve the full therapeutic potential of cladribine, it is important that clinicians are aware of the existence of NT-inhibiting medicinal products, various lifestyle drugs, and food components. This article reviews the existing knowledge on inhibitors of NT, which may alter cladribine absorption, distribution, and uptake into target cells, thereby summarizing the existing knowledge on optimized methods of administration and concomitant drugs that should be avoided during cladribine treatment.