Efficacy and Safety of Ponesimod Compared with Teriflunomide in Female Patients with Relapsing Multiple Sclerosis: Findings from the Pivotal OPTIMUM Study.

Background: Multiple sclerosis (MS) is threefold more prevalent in women than men. However, sex-specific efficacy analysis for MS disease-modifying therapies is not typically performed. Methods: Post hoc analyses of data from female patients enrolled in the phase 3, double-blind OPTIMUM study of relapsing MS were carried out. Eligible adults were randomized to ponesimod 20 mg or teriflunomide 14 mg once daily for up to 108 weeks. The primary endpoint was annualized relapse rate (ARR); secondary endpoints included change in symptom domain of Fatigue Symptom and Impact Questionnaire-Relapsing Multiple Sclerosis (FSIQ-RMS) at week 108, number of combined unique active lesions (CUALs) per year on magnetic resonance imaging, and time to 12- and 24-week confirmed disability accumulation (CDA). Results: A total of 735 female patients (581 of childbearing potential) were randomized to ponesimod (n = 363, 49.4%) or teriflunomide (n = 372, 50.6%). Relative risk reduction in the ARR for ponesimod versus teriflunomide was 33.1% (mean, 0.192 vs. 0.286, respectively; p < 0.002). Mean difference in FSIQ-RMS for ponesimod versus teriflunomide was -4.34 (0.12 vs. 4.46; p = 0.002); rate ratio in CUALs per year, 0.601 (1.45 vs. 2.41; p < 0.0001), and hazard ratio for time to 12- and 24-week CDA risk estimates, 0.83 (10.7% vs. 12.9%; p = 0.38) and 0.91 (8.8% vs. 9.7%; p = 0.69), respectively. Incidence of treatment-emergent adverse events was similar between treatment groups (89.0% and 90.1%). Conclusions: Analyses demonstrate the efficacy and safety of ponesimod, versus active comparator, for women with relapsing MS, supporting data-informed decision-making for women with MS. Clinical Trial Registration Number: NCT02425644.

The sphingosine-1-phosphate receptor 1 modulator ponesimod repairs cuprizone-induced demyelination and induces oligodendrocyte differentiation.

Sphingosine-1-phosphate receptor (S1PR) modulators are clinically used to treat relapse-remitting multiple sclerosis (MS) and the early phase of progressive MS when inflammation still prevails. In the periphery, S1PR modulators prevent lymphocyte egress from lymph nodes, hence hampering neuroinflammation. Recent findings suggest a role for S1PR modulation in remyelination. As the Giα-coupled S1P1 subtype is the most prominently expressed S1PR in oligodendrocyte precursor cells (OPCs), selective modulation (functional antagonism) of S1P1 may have direct effects on OPC functionality. We hypothesized that functional antagonism of S1P1 by ponesimod induces remyelination by boosting OPC differentiation. In the cuprizone mouse model of demyelination, we found ponesimod to decrease the latency time of visual evoked potentials compared to vehicle conditions, which is indicative of functional remyelination. In addition, the Y maze spontaneous alternations test revealed that ponesimod reversed cuprizone-induced working memory deficits. Myelin basic protein (MBP) immunohistochemistry and transmission electron microscopy of the corpus callosum revealed an increase in myelination upon ponesimod treatment. Moreover, treatment with ponesimod alone or in combination with A971432, an S1P5 monoselective modulator, significantly increased primary mouse OPC differentiation based on O4 immunocytochemistry. In conclusion, S1P1 functional antagonism by ponesimod increases remyelination in the cuprizone model of demyelination and significantly increases OPC differentiation in vitro.

Severity and worsening of fatigue among individuals with multiple sclerosis.

Background: Fatigue is associated with reduced quality of life and social participation, and poor employment outcomes. However, most studies examining fatigue are limited by small sample sizes or short follow-up periods. Objective: To characterize the natural history of fatigue. Methods: The North American Research Committee on Multiple Sclerosis Registry participants with ≥7 years of longitudinal data between 2004 and 2019 and a relapsing disease course were included. A subset of participants enrolled within 5 years of diagnosis was identified. The Fatigue Performance Scale assessed fatigue and ≥1-point increase in Fatigue Performance Scale sustained at the next survey defined fatigue worsening. Results: Of 3057 participants with longitudinal data, 944 were within 5 years of multiple sclerosis diagnosis. Most participants (52%) reported fatigue worsening during follow-up. Median time to fatigue worsening ranged from 3.5 to 5 years at lower levels of index fatigue. Fatigue worsening was associated with lower annual income, increasing disability, lower initial fatigue level, taking injectable disease-modifying therapies and increasing depression levels in the relapsing multiple sclerosis participants. Conclusion: Most multiple sclerosis participants early in their disease suffer from fatigue and at least half reported fatigue worsening over time. Understanding factors associated with fatigue may help to identify populations most at risk of fatigue worsening will be informative for the overall management of patients with multiple sclerosis.

The cystathionine-ß-synthase domains on the guanosine 5''-monophosphate reductase and inosine 5'-monophosphate dehydrogenase enzymes from Leishmania regulate enzymatic activity in response to guanylate and adenylate nucleotide levels.

The Leishmania guanosine 5'-monophosphate reductase (GMPR) and inosine 5'-monophosphate dehydrogenase (IMPDH) are purine metabolic enzymes that function maintaining the cellular adenylate and guanylate nucleotide. Interestingly, both enzymes contain a cystathionine-ß-synthase domain (CBS). To investigate this metabolic regulation, the Leishmania GMPR was cloned and shown to be sufficient to complement the guaC (GMPR), but not the guaB (IMPDH), mutation in Escherichia coli. Kinetic studies confirmed that the Leishmania GMPR catalyzed a strict NADPH-dependent reductive deamination of GMP to produce IMP. Addition of GTP or high levels of GMP induced a marked increase in activity without altering the Km values for the substrates. In contrast, the binding of ATP decreased the GMPR activity and increased the GMP Km value 10-fold. These kinetic changes were correlated with changes in the GMPR quaternary structure, induced by the binding of GMP, GTP, or ATP to the GMPR CBS domain. The capacity of these CBS domains to mediate the catalytic activity of the IMPDH and GMPR provides a regulatory mechanism for balancing the intracellular adenylate and guanylate pools.

Pilot study investigating the prognostic significance of thymidine phosphorylase expression in patients with metastatic breast cancer: a single institution retrospective analysis.

BACKGROUND: The thymidine phosphorylase (TP) enzyme is expressed in higher levels in cancer tissue when compared with normal tissue. It is involved in the intratumoral activation of widely prescribed pyrimidine-derived antimetabolites such as 5'-deoxy-5-fluorouridine and capecitabine (Xeloda(®)). The purpose of this study was to determine the clinical correlation between TP expression in tumor tissue and the clinical outcome of capecitabine-based therapy in patients with locally advanced (stage III) or metastatic breast cancer (stage IV). METHODS: The following variables were analyzed as potential determinants of benefit from a capecitabine-based therapy: TP expression, estrogen receptor (ER) and progesterone receptor (PR) status, human epidermal growth factor receptor-2 status, and Ki67 status. This was accomplished by immunohistochemical analysis of paraffin-embedded cancer tissues from 18 patients with breast cancer treated with at least one cycle of capecitabine. Clinical outcome was measured as time to progression. RESULTS: TP staining intensities in both the invasive and in situ components in patients with lobular and ductal carcinomas were reported. Higher levels of TP in the invasive component were expressed in ER-negative tumors when compared with ER-positive tumors (P<0.05). The ER-positive group expressing lower levels of TP had a median time to progression of 13 months compared with the ER-negative group expressing higher levels of TP which had a median time to progression of 7.5 months (P=0.14). CONCLUSION: Patients with ER-positive tumors expressing lower levels of TP exhibit a longer time to progression when compared with patients with ER-negative tumors. Consequently, tumor TP expression does not seem to predict the outcome of capecitabine-based chemotherapy.

ZRX1, the first EGFR inhibitor-capecitabine based combi-molecule, requires carboxylesterase-mediated hydrolysis for optimal activity.

Capecitabine, an orally available prodrug of 5-FU, requires activation by carboxylesterase (CES) enzymes present in the liver to generate 5'-deoxy-5-flurocytidine ribose (5'-DFCR). The deamination of the latter by cytidine deaminase gives 5'-deoxy-5-fluorouridine ribose (5'-DFUR). Finally, the conversion of 5'-DFUR to the cytotoxic drug 5-FU, occurs primarily in the tumour and is catalyzed by thymidine phosphorylase (TP). Accordingly, it was surmised that events associated with an increase of TP levels should enhance the potency of capecitabine and its metabolites. EGFR inhibition was found to be one such event. The observed synergy between gefitinib and 5'-DFUR has inspired the design of single molecules capable of acting as prodrugs of both an EGFR inhibitor and 5-FU. Here, we report on the synthesis and characterization of one such molecule, ZRX1, that consists of an acetylated 5'-DFCR moiety linked to a quinazoline inhibitor of EGFR through an alkyl dicarbamate spacer that requires CES activation to generate the two active metabolites. Our results showed that ZRX1 was ineffective as an intact molecule. However, when CES was present, ZRX1 induced an increase in EGFR inhibition, TP expression, DNA damage and apoptosis. ZRX1 was, at least, 3-fold more potent than capecitabine and 5'-DFUR and recapitulated the effects of the combination treatments. LC-MS analysis showed that in the presence of CES, ZRX1 is metabolized into a mixture of bioactive quinazoline derivatives and 5'-DFCR derived metabolites. Our results in toto, suggest that capecitabine-based EGFR targeting combi-molecules of the same type than ZRX1, have the potential to induce stronger growth inhibitory potency than capecitabine, 5'-DFUR or single EGFR inhibitors and equivalent potency when compared with combinations of EGFR inhibitors + 5'-DFUR.

Inhibition of EGFR phosphorylation in a panel of human breast cancer cells correlates with synergistic interactions between gefitinib and 5'-DFUR, the bioactive metabolite of Xeloda.

Capecitabine (Xeloda) is a prodrug of 5-FU used in the clinical management of advanced breast cancer. It is metabolized first in the liver by carboxylesterases to generate 5'-deoxy-5-flurocytidine ribose (5'-DFCR), which is subsequently converted to 5'-deoxy-5-fluorouridine ribose (5'-DFUR) by cytidine deaminase in tumour and normal tissues. The conversion of 5'-DFUR to the cytotoxic 5-FU, occurs primarily in the tumour and is catalyzed by thymidine phosphorylase (TP). Prior work in head and neck cancer showed that cell treatment with an inhibitor of the epidermal growth receptor (EGFR) gefitinib led to an increase in TP expression and sensitized them to 5'-DFUR. This work seeks to investigate the factors influencing the potency of gefitinib + 5'-DFUR combination. Here, we studied these factors in a panel of six human breast cancer cell lines, with varied levels of sensitivity to gefitinib. Our results first confirmed that 5'-DFUR potency linearly correlates with TP basal levels in the panel of cell lines. In contrast, the strength of the synergistic effect of the gefitinib + 5'-DFUR combination, as measured by their combination indices (CI) correlates with pEGFR percent inhibition and with the modulation of TP expression by gefitinib (as quantitated by TP fold change) rather than TP basal levels. The results, in toto, suggest that the extent of modulation of TP by gefitinib may be used as a predictor of tumour sensitivity to gefitinib + capecitabine/5'-DFUR combinations.