Medicinal Chemistry of Multiple Sclerosis: Focus on Cladribine

Magnetic Multi-Enzymatic System for Cladribine Manufacturing

Enzyme-mediated processes have proven to be a valuable and sustainable alternative to traditional chemical methods. In this regard, the use of multi-enzymatic systems enables the realization of complex synthetic schemes, while also introducing a number of additional advantages, including the conversion of reversible reactions into irreversible processes, the partial or complete elimination of product inhibition problems, and the minimization of undesirable by-products. In addition, the immobilization of biocatalysts on magnetic supports allows for easy reusability and streamlines the downstream process. Herein we have developed a cascade system for cladribine synthesis based on the sequential action of two magnetic biocatalysts. For that purpose, purine 2′-deoxyribosyltransferase from Leishmania mexicana (LmPDT) and Escherichia coli hypoxanthine phosphoribosyltransferase (EcHPRT) were immobilized onto Ni2+-prechelated magnetic microspheres (MagReSyn®NTA). Among the resulting derivatives, MLmPDT3 (activity: 11,935 IU/gsupport, 63% retained activity, operational conditions: 40 °C and pH 5–7) and MEcHPRT3 (12,840 IU/gsupport, 45% retained activity, operational conditions: pH 5–8 and 40–60 °C) emerge as optimal catalysts for further synthetic application. Moreover, the MLmPDT3/MEcHPRT3 system was biochemically characterized and successfully applied to the one-pot synthesis of cladribine under various conditions. This methodology not only displayed a 1.67-fold improvement in cladribine synthesis (compared to MLmPDT3), but it also implied a practically complete transformation of the undesired by-product into a high-added-value product (90% conversion of Hyp into IMP). Finally, MLmPDT3/MEcHPRT3 was reused for 16 cycles, which displayed a 75% retained activity.

Cladribine Tablets for Relapsing-Remitting Multiple Sclerosis: A Clinician's Review

Multiple sclerosis (MS) is a chronic neurodegenerative disease characterized by inflammation and demyelination for which there is currently no cure; therefore, the aim of therapy is to reduce the risk of relapse and disability progression. The treatment options for MS have increased greatly in recent years with the development of several disease-modifying therapies (DMTs) and the advent of immune reconstitution therapy (IRT). IRTs are administered in short-dosing periods to produce long-term effects on the immune system. Treatment with an IRT is based on the 3Rs: reduction, repopulation, and reconstitution of lymphocytes, which leads to restoration of immune effector functions. Cladribine tablets represent a selective, high-efficacy, oral form of IRT for patients with MS that targets lymphocytes and spares innate immune cells. Patients require only two weekly treatment courses, with each course comprising two treatment weeks, in Years 1 and 2; therefore, cladribine tablets are associated with a lower monitoring burden than many other DMTs, while short dosing periods can help to improve adherence. This review provides an overview of IRT and offers the clinician's perspective on the current MS treatment landscape, with a focus on practical advice for the management of patients undergoing treatment with cladribine tablets based on the most recent evidence available, including risks associated with COVID-19 and recommendations for vaccination in patients with MS.

Green Production of Cladribine by Using Immobilized 2'-Deoxyribosyltransferase from Lactobacillus delbrueckii Stabilized through a Double Covalent/Entrapment Technology

Nowadays, enzyme-mediated processes offer an eco-friendly and efficient alternative to the traditional multistep and environmentally harmful chemical processes. Herein we report the enzymatic synthesis of cladribine by a novel 2'-deoxyribosyltransferase (NDT)-based combined biocatalyst. To this end, Lactobacillus delbrueckii NDT (LdNDT) was successfully immobilized through a two-step immobilization methodology, including a covalent immobilization onto glutaraldehyde-activated biomimetic silica nanoparticles followed by biocatalyst entrapment in calcium alginate. The resulting immobilized derivative, SiG_{PEI 25000}-LdNDT-Alg, displayed 98% retained activity and was shown to be active and stable in a broad range of pH (5-9) and temperature (30-60 °C), but also displayed an extremely high reusability (up to 2100 reuses without negligible loss of activity) in the enzymatic production of cladribine. Finally, as a proof of concept, SiG_{PEI 25000}-LdNDT-Alg was successfully employed in the green production of cladribine at mg scale.