The primary target of FP802 dihydrochloride is the TwinF interface of the NMDAR/TRPM4 death complex. This complex consists of the N-methyl-D-aspartate receptor (NMDAR) and the transient receptor potential melastatin 4 (TRPM4) channel. Under pathological conditions, excessive NMDAR activation leads to excitotoxicity, which is mediated through interaction with TRPM4. FP802 dihydrochloride disrupts the physical interaction between NMDAR and TRPM4, thereby selectively eliminating eNMDAR-mediated toxicity without affecting physiological NMDAR functions. This unique selectivity profile distinguishes it from conventional NMDAR antagonists. No other primary targets have been identified.

FP802 (8 μM, 24–72 h) hydrochloride effectively disrupts the NMDAR/TRPM4 complex and provides neuroprotection in cell models, but it does not directly promote or inhibit neurite growth[1]. FP802 (10 μM, 30 min) hydrochloride exhibits strong neuroprotective effects, resisting glutamate (20 μM)-mediated toxicity (IC50 = 8.7 µM) and restoring NMDA-inhibited early gene expression to physiological levels[2]. FP802 hydrochloride did not show antagonistic activity against NMDAR in HEK293 cells (IC50 of GluN1/GluN2A and GluN1/GluN2B were both > 250 mM)[2]. FP802 (30 min) hydrochloride was able to dose-dependently block post-mitotic death of neurons in disease-specific induced pluripotent stem cell (iPSC)-derived forebrain organoids of sporadic ALS [2].

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In cell-free assays, FP802 dihydrochloride at 8 microM for 24-72 hours effectively dissociates the NMDAR/TRPM4 complex in cellular models. The compound demonstrates an IC50 of 8.7 microM against neurotoxicity induced by pennisetum glaucum (20 microM) in cell-based systems. FP802 dihydrochloride neither directly promotes nor inhibits neurite outgrowth at effective concentrations, indicating its selective action on pathological complex formation without affecting normal neuronal development. The compound restores NMDA-suppressed immediate early gene expression levels to physiological conditions, confirming its ability to normalize NMDAR signaling.

FP802 (10 and 40 mg/kg, epidermal, once daily for 4 months) dihydrochloride improved cognitive function, prevented neuronal structural damage, and reduced amyloid pathology in 5xFAD mice [1]. FP802 (40 mg/kg, subcutaneous injection, once daily for approximately 4 weeks starting from week 15) dihydrochloride safely prevented ALS motor neuron shortening and prolonged its survival via the NMDAR/TRPM4 complex [2].

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In cellular models, FP802 dihydrochloride (10 microM, 30 minutes) significantly counteracts neurotoxicity induced by pennisetum glaucum (20 microM), with an IC50 of 8.7 microM. The compound restores NMDA-suppressed immediate early gene expression levels to physiological conditions, confirming its ability to normalize NMDAR signaling without completely blocking the receptor. FP802 dihydrochloride (8 microM, 24-72 hours) effectively dissociates the NMDAR/TRPM4 complex and exerts neuroprotective effects while neither directly promoting nor inhibiting neurite outgrowth, indicating no adverse effects on normal neuronal development and differentiation.

In vivo, FP802 dihydrochloride was administered orally at doses of 10 mg/kg and 40 mg/kg once daily for 4 months in 5xFAD Alzheimer‘s disease mouse model. Treatment improved cognitive function, effectively prevented neuronal degeneration, and reduced amyloid pathology in the brain. In ALS model mice, FP802 dihydrochloride was administered subcutaneously at 40 mg/kg once daily starting at week 15 for 4 consecutive weeks. The compound safely delayed the progression of motor neuron degeneration and significantly extended survival time. These results demonstrate broad neuroprotective efficacy in two distinct neurodegenerative disease models.

Real Time qPCR[1]
Cell Types: mouse cortical neurons
Tested Concentrations: 10 μM
Incubation Duration: 30 min
Experimental Results: Eliminated the transcriptional shut-off induced by eNMDARs and boosted the NMDA bath application-induced expression of the immediate-early genes (IEGs) Atf3, Arc, Bdnf, cFos, Inhibin beta A, and Npas4 to reach levels that were comparable to those achieved by Bicuculline induced action potential bursting.

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Not specifically reported for FP802 dihydrochloride in the available literature. The compound‘s mechanism involves disrupting protein-protein interactions between NMDAR and TRPM4. Standard assays for such interactions could include co-immunoprecipitation (Co-IP) using specific antibodies against NMDAR subunits or TRPM4. Surface plasmon resonance (SPR) or biolayer interferometry (BLI) could measure direct binding affinity between purified NMDAR and TRPM4 fragments in the presence or absence of the compound. ELISA-based protein-protein interaction assays using recombinant TwinF domain fragments are also applicable.

Animal/Disease Models: 5xFAD transgenic mice and wild-type littermates[1]
Doses: 10 and 40 mg/kg
Route of Administration: p.o., daily for 4 months
Experimental Results: Showed no apparent adverse effects on the liver, kidney, or heart. Reduced the complex formation of GluN2B with TRPM4 in the 5xFAD mice at both 10 and 40 mg/kg. Reduced complex formation of GluN2A with TRPM4 at 40 mg/kg. Significantly decreased the interaction between NMDAR and TRPM4 without affecting the total protein levels of GluN2A, GluN2B, or TRPM4. Led to a significant increase in the time 5xFAD mice spent in the target quadrant and the frequency with which they crossed the platform's prior location at the dose of 40 mg/kg, compared to vehicle. Increased the time 5xFAD mice spent exploring the novel object in the Novel Object Recognition (NOR) test and the displaced object in the Novel Location Recognition (NLR) test relative to vehicle treatment. Prevented the shift of mitochondrial morphologies from normal to pathological phenotypes in both CA1 and CA3. Effectively preserved dendritic trees in 5xFAD mice as compared to controls, as demonstrated by increased total dendritic length and numbers of crossings in the Sholl analysis. Prevented the increase in the density of 'apparent orphaned synapses' in both stratum oriens (CA1 basal dendrites) and stratum radiatum (CA1 apical dendrites) of 5xFAD mice. Prevented the loss of excitatory and inhibitory synapses and the associated structural deterioration of postsynaptic densities (PSD) in the basal and apical dendrites of CA1 neurons, thereby preserving synaptic integrity in 5xFAD mice. Led to a 25-40% reduction in Aβ plaque load, significantly limiting plaque development without completely preventing its formation.

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Animal/Disease Models: Male SOD1G93A transgenic mice and wild-type littermates[2]
Doses: 40 mg/kg
Route of Administration: s.c., daily from ~week 15 for 4 weeks
Experimental Results: Disrupted he interaction of TRPM4 with the NMDAR subunit GluN2B in mice spinal cord. Significantly better neurological scores and less body weight loss than vehicle-treated controls. Significantly improved motor performance (increased total distance traveled and rearing frequency in the open field). Significantly extended the lifespan of SOD1G93A mice (survival median increased from 151 to 164 days). Preserved larger soma sizes of lumbar spinal motor neurons compared to the control group at week 19. Significantly reduced serum NfL levels while showing no effect on spinal microglial response or EAAT2 expression. Showed no adverse effects on liver, kidney, heart, or blood counts.

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For FP802 dihydrochloride cell-based assays, cellular models include primary neurons or neuronal cell lines (e.g., SH-SY5Y, primary cortical neurons) expressing NMDAR and TRPM4. Cells are cultured in neurobasal medium with B27 supplement. Excitotoxicity is induced using NMDA (10-100 microM) or other neurotoxic insults. FP802 dihydrochloride is added at 1-20 microM for 30 minutes to 72 hours. Cell viability is measured by MTT, LDH release, or calcein-AM staining. NMDAR/TRPM4 complex formation is assessed by proximity ligation assay or co-immunoprecipitation. Immediate early gene expression (c-Fos, Arc) is measured by qRT-PCR or Western blotting.

For FP802 dihydrochloride, two in vivo models have been described. In the 5xFAD Alzheimer‘s disease mouse model, compound is administered orally (by gavage) at 10 or 40 mg/kg once daily for up to 4 months. Endpoints: cognitive function (Morris water maze, novel object recognition), neuronal degeneration (Nissl staining, NeuN immunohistochemistry), amyloid pathology (Abeta plaque burden by Thioflavin S or 6E10 staining). In the ALS mouse model (e.g., SOD1-G93A), FP802 dihydrochloride (40 mg/kg SC once daily, starting at week 15 for 4 weeks) delays motor neuron degeneration and extends survival time. Additional endpoints include motor function tests (rotarod, grip strength).

Not specifically reported for FP802 dihydrochloride in the available literature. The compound is described as orally active, indicating sufficient absorption following oral administration. As a small molecule inhibiting protein-protein interactions within a death complex, it likely exhibits characteristics suitable for central nervous system penetration given its efficacy in brain-related disease models. Detailed PK parameters such as oral bioavailability (%), half-life, volume of distribution, Cmax, Tmax, clearance, and AUC have not been reported in the available literature for this compound.

[1]. The NMDAR/TRPM4 death complex is a major promoter of disease progression in the 5xFAD mouse model of Alzheimer's disease. Mol Psychiatry. 2025 Aug 26.

[2]. TwinF interface inhibitor FP802 stops loss of motor neurons and mitigates disease progression in a mouse model of ALS. Cell Rep Med. 2024 Feb 20;5(2):101413.

Specific toxicity data for FP802 dihydrochloride are not extensively reported in the available literature. The compound is intended for research use only and not for human therapeutic applications. In animal studies, FP802 dihydrochloride administered at doses up to 40 mg/kg (oral or subcutaneous) for up to 4 months was described as safe and well-tolerated, with no significant adverse events reported. The compound demonstrated neuroprotective efficacy without apparent systemic toxicity at these doses. No acute or chronic toxicity studies beyond the efficacy studies have been described. Standard safety precautions for handling should be observed.

C11H19CL3N2

285.64

2490401-57-3

FP802

White to off-white solid powder

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O : ~116.67 mg/mL (~408.45 mM; with sonication)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)