FTY720-d4 Hydrochloride

Target of Action

Fingolimod-d4 Hydrochloride, also known as FTY720-d4 Hydrochloride, primarily targets the sphingosine 1-phosphate receptors (S1PRs) found on lymphocytes and other organs . The modulation of these receptors is crucial in managing multiple sclerosis (MS) symptoms .

Mode of Action

Fingolimod-d4 Hydrochloride acts as a sphingosine 1-phosphate receptor modulator . It is metabolized to its active form, fingolimod-phosphate, which binds to sphingosine 1-phosphate receptors 1, 3, 4, and 5 .

Biochemical Pathways

Fingolimod-d4 Hydrochloride affects several biochemical pathways. It induces metabolic reprogramming in brain regions, upregulating oxidative phosphorylation while downregulating glycolysis and the pentose phosphate pathway . It also modulates neuroinflammation by upregulating retrograde endocannabinoid signaling and autophagy pathways, and downregulating neuroinflammation-related pathways including neutrophil degranulation and the IL-12 mediated signaling pathway .

Pharmacokinetics

It’s known that the compound is given orally . More research is needed to fully understand the ADME properties of Fingolimod-d4 Hydrochloride and their impact on bioavailability.

Result of Action

The molecular and cellular effects of Fingolimod-d4 Hydrochloride’s action are profound. It reduces the number of lymphocytes in the peripheral blood, which is believed to be effective in treating MS due to the reduced lymphocytes into the CNS . It also induces numerous biological effects, including endothelial cell-cell adhesion, angiogenesis, vascular integrity, and cardiovascular function .

Action Environment

The action environment of Fingolimod-d4 Hydrochloride is primarily within the immune system and the CNS . The interaction with s1p receptors in various tissues accounts for the reported adverse effects

Biochemical Properties

Fingolimod-d4 Hydrochloride interacts with sphingosine 1-phosphate receptors (S1PRs) to bring about an array of pharmacological effects . It exerts inhibitory effects on sphingolipid pathway enzymes, inhibits histone deacetylases, transient receptor potential cation channel subfamily M member 7 (TRMP7), cytosolic phospholipase A2α (cPLA2α), reduces lysophosphatidic acid (LPA) plasma levels, and activates protein phosphatase 2A (PP2A) .

Cellular Effects

Fingolimod-d4 Hydrochloride has profound effects on various types of cells and cellular processes. It can profoundly reduce T-cell numbers in circulation and the CNS, thereby suppressing inflammation and MS . It also induces apoptosis, autophagy, cell cycle arrest, epigenetic regulations, macrophages M1/M2 shift and enhances BDNF expression .

Molecular Mechanism

Fingolimod-d4 Hydrochloride exerts its effects at the molecular level through several mechanisms. It binds to S1P receptor4 (S1PR4) that is primarily expressed in lymphocytes and hematopoietic tissues . It can induce apoptotic pathways by activation of caspase cascades, enhancing PTEN which inhibits pAkt, and inducing (ROS-JNK-p53) loop-dependent autophagy .

Temporal Effects in Laboratory Settings

It has been shown that the drug has a significant therapeutic effect in immunodeficient mice, not in immunocompetent mice .

Dosage Effects in Animal Models

In an animal model of genetic absence epilepsy, Fingolimod (1 mg/kg) showed transient antiepileptic effects and longer-lasting anti-cognition decline . During the chronic epileptic phase of the mouse kainate model, 6 mg/kg of the drug also showed neuroprotective and anti-gliotic effects besides reducing seizure frequency .

Metabolic Pathways

Fingolimod-d4 Hydrochloride is involved in the sphingosine 1-phosphate (S1P) pathway . It is phosphorylated to Fingolimod-phosphate by two protein kinases, type-1 and type-2 sphingosine kinase (SphK1 and -2), enabling it to interact with sphingosine receptors .

Transport and Distribution

It is known that Fingolimod binds to S1P receptor4 (S1PR4) that is primarily expressed in lymphocytes and hematopoietic tissues .

Subcellular Localization

It is known that Fingolimod activates PP2A that plays a principal role as a regulator of cell cycle/division and growth .

FTY720-d4 Hydrochloride, a deuterated form of Fingolimod (FTY720), is a potent immunomodulatory compound primarily recognized for its role in treating multiple sclerosis (MS) and other autoimmune diseases. This article delves into the biological activity of FTY720-d4, including its mechanisms of action, effects on immune cell trafficking, and therapeutic implications based on diverse research findings.

Overview of this compound

FTY720 is a sphingosine-1-phosphate (S1P) receptor modulator that exerts its effects by phosphorylating into FTY720-P, which acts as an agonist for S1P receptors. The deuterated version, FTY720-d4, is designed to enhance pharmacokinetic properties and reduce metabolic degradation, potentially leading to improved therapeutic efficacy and safety profiles.

The primary mechanism through which FTY720-d4 functions involves the modulation of lymphocyte trafficking. Upon phosphorylation, FTY720-P binds to S1P receptors on lymphocytes, leading to their internalization and subsequent sequestration in lymphoid organs. This action effectively reduces the number of circulating lymphocytes and inhibits their migration into inflamed tissues.

Table 1: Comparison of FTY720 and this compound

Multiple Sclerosis

FTY720 has demonstrated significant efficacy in reducing relapse rates in patients with relapsing forms of MS. A clinical trial showed that patients receiving 5 mg daily had a lower incidence of gadolinium-enhancing lesions compared to placebo groups .

In animal models of MS, such as the experimental autoimmune encephalomyelitis (EAE) model, FTY720 treatment resulted in reduced clinical severity and inflammatory cell infiltration into the central nervous system (CNS) . The application of FTY720-d4 could enhance these effects due to its altered pharmacokinetics.

Alzheimer's Disease

Recent studies have explored the potential neuroprotective effects of FTY720 in models of Alzheimer's disease (AD). In APP/PS1 transgenic mice, chronic administration of FTY720 improved long-term potentiation (LTP) deficits and reduced microglial activation, suggesting that it may ameliorate synaptic dysfunction associated with AD . The ability of FTY720-d4 to offer similar or enhanced benefits warrants further investigation.

Case Studies and Clinical Evidence

In a Phase II clinical trial involving renal transplantation, FTY720 was shown to be effective in preventing acute rejection. Patients receiving varying doses displayed a significant reduction in biopsy-confirmed acute rejection rates compared to those on standard therapies . The potential application of FTY720-d4 in this context could lead to improved outcomes due to its enhanced stability and efficacy.

Multiple Sclerosis Treatment

FTY720 (Fingolimod) has been widely studied for its efficacy in treating relapsing-remitting multiple sclerosis (RRMS). Clinical trials have demonstrated that FTY720 significantly reduces the frequency of relapses and the progression of disability in MS patients. For example:

• Phase II Trials : A study involving 281 patients showed that FTY720 at doses of 1.25 mg and 5.0 mg daily resulted in a significant reduction in gadolinium-enhancing lesions on MRI compared to placebo .
• Phase III FREEDOMS Study : This study confirmed that patients receiving FTY720 had lower annualized relapse rates (0.18 and 0.16) compared to the placebo group (0.40) .

Neuroprotective Effects

Recent investigations have explored the neuroprotective effects of FTY720 in models of Alzheimer's disease (AD). In APP/PS1 transgenic mice, chronic treatment with FTY720:

• Rescued synaptic pathology and improved spatial memory performance.
• Reduced microglial activation and astrogliosis, indicating a decrease in neuroinflammation .
• Decreased amyloid-beta plaque formation in the hippocampus, suggesting a potential role in mitigating AD pathology .

Organ Transplantation

FTY720 has shown promise in preventing acute rejection in renal transplantation:

• In a multicenter study, FTY720 was compared with mycophenolate mofetil (MMF) and demonstrated comparable efficacy in preventing acute rejection at a dose of 2.5 mg .
• The drug's unique mechanism allows it to enhance allograft survival without impairing T cell function, making it an attractive option for immunosuppression .

Case Studies

Basic Research Questions

Q. What is the primary mechanism of FTY720-d4 Hydrochloride in modulating immune responses?

FTY720-d4, a deuterium-labeled analog of FTY720, acts as a sphingosine 1-phosphate (S1P) receptor agonist. Its phosphorylated form (FTY-P) binds to S1P receptors (S1PR1, S1PR3, S1PR4, and S1PR5), inducing receptor internalization and sequestering lymphocytes in secondary lymphoid tissues, thereby reducing peripheral lymphocyte migration. This mechanism is critical in autoimmune and transplantation models, as demonstrated by its efficacy in experimental autoimmune encephalomyelitis (EAE) and graft rejection studies .

Q. Which experimental models are validated for studying FTY720-d4’s therapeutic effects?

• EAE in Lewis rats : Used to assess suppression of T-cell infiltration into the CNS, with outcomes measured via immunohistochemistry (T-cell receptor staining) and cytokine profiling (IL-2, IL-6, IFN-γ) .
• Corneal angiogenesis models : Evaluates antiangiogenic activity by quantifying VEGF- or S1P-induced vascular growth .
• Murine asthma models : Tests local administration effects on dendritic cell migration and Th2 responses via inhaled FTY720 .

Q. What pharmacokinetic parameters are critical for in vivo study design?

Key parameters include:

• Tissue distribution : High partition coefficients in lymph nodes (RT = 22.9) and spleen (RT = 34.7), indicating tissue sequestration .
• Terminal half-life : ~23.4 hours in rats, requiring extended sampling periods in chronic studies .
• Bioavailability : 71% oral absorption in rats, necessitating dose adjustments for oral vs. intravenous administration .

Advanced Research Questions

Q. How does phosphorylation status influence FTY720-d4’s receptor selectivity and activity?

FTY720-d4 requires phosphorylation by sphingosine kinase to activate S1P receptors. Phosphorylated FTY720 (FTY-P) exhibits differential receptor agonism:

• S1P1 : Mediates lymphocyte sequestration via receptor internalization .
• S1P3 : Drives endothelial nitric oxide synthase (eNOS)-dependent vasodilation, complicating cardiovascular safety assessments .
  Methodologically, sphingosine kinase inhibitors (e.g., DMS) or kinase-deficient models can isolate phosphorylation-dependent effects .

Q. How to resolve contradictions between in vitro and in vivo data on S1P receptor subtype roles?

In vitro studies using transfected HEK293 cells show FTY-P internalizes S1P1 but not VEGF receptors , whereas in vivo models reveal S1P3-mediated vasodilation . To address discrepancies:

• Use receptor knockout mice (e.g., S1P3−/−) to isolate subtype-specific effects.
• Combine phosphoproteomics with tissue-specific pharmacokinetic modeling to contextualize receptor activation .

Q. What analytical methods quantify FTY720-d4 and metabolites in biological matrices?

• LC-MS/MS : Validated for blood and tissue samples, with sensitivity to distinguish deuterated FTY720-d4 from endogenous sphingolipids .
• Mass spectrometry : Detects rapid phosphorylation kinetics (≥90% conversion within 10 minutes in endothelial cells) .

Q. Can route of administration alter FTY720-d4’s efficacy-to-safety profile?

• Inhalation : Reduces eosinophilic inflammation in asthma models without systemic lymphopenia, suggesting localized DC modulation .
• Oral/IV : Induces dose-dependent lymphopenia (IC50 = 0.48 µg/L in monkeys), requiring careful monitoring of lymphocyte subsets .

Q. Does FTY720-d4 synergize with VEGF inhibitors in antiangiogenic therapy?

In melanoma models, FTY720 combined with PTK787/ZK222584 (VEGFR inhibitor) showed additive reduction in tumor angiogenesis. However, FTY720 alone inhibits S1P1-mediated endothelial migration, while VEGF inhibitors target proliferation. Co-administration studies should include dynamic contrast-enhanced MRI to assess vascular permeability .

Q. Methodological Considerations

• Dose-response modeling : Use indirect response models to link FTY720-d4 concentrations to lymphocyte trafficking dynamics (e.g., k_in = 6014 cells/µL/h for total lymphocytes) .
• Tissue-specific PK/PD modeling : Incorporate permeability-limited compartments for brain and lymph nodes to predict CNS efficacy .

FTY720 (Fingolimod Hydrochloride)

• Structure: Non-deuterated parent compound (C₁₉H₃₃NO₂·HCl) .
• Pharmacology: Binds to S1P receptors, inducing receptor internalization and immunosuppression .
• Applications : Clinically used for relapsing-remitting multiple sclerosis.
• Key Difference : Lacks deuterium, leading to faster metabolic clearance compared to FTY720-d4 .

FTY720 Phosphate (Active Metabolite)

• Structure: Phosphorylated form of FTY720 (C₁₉H₃₃NO₅P) .
• Pharmacology : Active metabolite responsible for S1P receptor modulation .
• Applications : Studied for enhanced bioavailability and prolonged receptor engagement.
• Key Difference : Requires phosphorylation for activity, unlike FTY720-d4, which is used primarily for tracking unmetabolized drug .

Structural Analogs with Modified Substituents

Several analogs from exhibit distinct pharmacological profiles:

Isotopic and Functional Derivatives

• Azido-FTY720 : Contains an azide group for click chemistry applications in target identification .
• FTY720-Mitoxy : Mitochondria-targeted derivative for studying localized effects .
• Deuterated Analogs (e.g., FTY720-d4) : Prioritize metabolic stability over altered receptor interaction .

Data Tables

Table 1: Key Properties of FTY720-d4 Hydrochloride vs. Select Analogs