Safety, Tolerability and Pharmacokinetics of Benfo-Oxythiamine (B-OT) in Healthy Volunteers (BOOST)

Assessing the Safety, Tolerability and Pharmacokinetics of Benfo-Oxythiamine (B-OT) in Healthy Volunteers - An Open Label, Phase I Study

The goal of this clinical trial was to learn about the safety and tolerability of an investigational drug called Benfo-oxythiamine (B-OT) in healthy male volunteers. Researchers are studying B-OT to see if it might be used to treat infectious diseases and cancer. This study also looked at how the drug enters, moves through, and leaves the body.

The main questions it aimed to answer were:

• Is B-OT safe for humans to take?
• What medical problems do participants have when taking B-OT?
• How much of the drug gets into the blood?

Participants:

• Took B-OT capsules by mouth either once (single dose group) or once a day for 7 days (multiple dose group).
• Stayed in the clinic for several days (4 to 8 nights) for close monitoring.
• Gave blood and urine samples for laboratory tests;
• Had physical exams, heart rhythm checks (ECG), and vital sign checks (blood pressure, heart rate, breathing rate, and temperature).

Study Overview

• Status: Completed
• Conditions: Healthy Volunteers
• Intervention / Treatment: Drug: Benfo-oxythiamine

Detailed Description

• This Phase 1 study was originally designed and conducted in 2022 to assess the safety and pharmacokinetics of Benfo-Oxythiamine (B-OT) for the potential treatment of SARS-CoV-2 infection (COVID-19), as defined in the study protocol.
• B-OT targets the Transketolase (TKT)/Transketolase-like 1 (TKTL1) pathway. Inhibition of this pathway affects glucose metabolism, a mechanism relevant to both viral replication (such as SARS-CoV-2) and tumor cell proliferation (Oncology).
• Current Scientific Context (2026): While the study was conducted under a COVID-19 indication, the safety and PK data generated are now also supporting development in Oncology. Recent literature (>2022) has further validated TKT/TKTL1 as a key target in e.g., chemotherapy resistance and cell cycle control. This recent literature functions as supporting evidence for the drug target. The results of this clinical phase I study are therefore also directly relevant for future investigations in cancer indications.
• Detailed Description: Scientific Rationale, Mechanism of Action, and Preclinical Validation of Benfo-oxythiamine (B-OT)
• 1. General Introduction and Target Biology Benfo-oxythiamine (B-OT) is a novel, lipophilic S-benzoyl-O-monophosphate prodrug developed to target fundamental metabolic dependencies across multiple disease states. It is important to emphasize that all subsequent mechanisms are validated in in vitro and in vivo preclinical models, providing a robust biological basis for the potential observed clinical responses across different indications. Upon administration, B-OT crosses cellular membranes and is rapidly hydrolyzed by ecto-alkaline phosphatases and cytosolic esterases to release the thiamine antagonist oxythiamine (OT). Intracellularly, OT is metabolized by thiamine pyrophosphokinase (TPK) into its biologically active form, oxythiamine pyrophosphate (OTP). OTP functions as a potent, competitive inhibitor of thiamine diphosphate (ThDP)-dependent enzymes. Its primary therapeutic targets are Transketolase (TKT) and Transketolase-like 1 (TKTL1), which serve as critical "gatekeepers" in the non-oxidative branch of the pentose phosphate pathway (PPP). By inhibiting these enzymes, OTP disrupts the supply of Ribose-5-Phosphate (R5P) needed for nucleotide synthesis, Nicotinamide Adenine Dinucleotide Phosphate (NADPH) for redox defense, and Acetyl-CoA for lipid biosynthesis, collapsing the metabolic infrastructure required for rapid cellular proliferation and pathogen replication.
• 2. Scientific Rationale in Oncology The therapeutic rationale for targeting TKT and TKTL1 in cancer addresses cell cycle dysregulation, metabolic reprogramming, immune evasion, and therapy resistance.
• Cell Cycle Control and "Metabolic Sensing": TKTL1 acts as a direct regulator of the cell cycle. The TKTL1-TKT heterodimer generates R5P, which binds directly to TKTL1. This complex acts as a metabolic sensor, recruiting the SCF-β-TRCP ubiquitin ligase complex to the cell cycle inhibitor CDH1, triggering its proteasomal degradation and allowing the cell to transition from G1 to the S phase. Pharmacological inhibition by B-OT depletes R5P, stabilizing CDH1 and enforcing a profound G1 cell cycle arrest, which sensitizes tumor cells to apoptosis.
• Reversal of Chemoresistance and the Warburg Effect: TKT drives metabolic resistance via a physical interaction with Pyruvate Kinase M2 (PKM2), preventing its tetramerization and forcing the cell into aerobic glycolysis (the Warburg effect). This provides the ATP and lactate necessary to shield the tumor from DNA-damaging drugs. TKT inhibition dismantles this TKT-PKM2 interaction, restoring mitochondrial OXPHOS, reducing lactate, and overcoming resistance to agents like cisplatin in renal cell carcinoma. Additionally, standard genotoxic therapies (e.g., UVA irradiation, Adriamycin) induce TKTL1 and the Warburg effect as a survival mechanism against starvation and oxidative stress; inhibiting this pathway strips tumors of this acquired resistance.
• Nucleotide Stress and DNA Repair Impairment: Rapidly dividing cells require a continuous supply of R5P from the PPP to synthesize nucleotides for repairing double-strand DNA breaks. OT treatment induces severe "nucleotide stress," impairing homologous recombination and non-homologous end joining, evidenced by the accumulation of the DNA damage marker γ-H2AX. Consequently, B-OT serves as a potent radiosensitizer and chemosensitizer in highly aggressive tumors.
• Lipid Starvation and Epigenetic Disruption: TKTL1 utilizes a unique one-substrate phosphoketolase reaction to cleave xylulose-5-phosphate into glyceraldehyde-3-phosphate and Acetyl-CoA without CO2 loss. This provides cytosolic Acetyl-CoA essential for de novo lipid synthesis and histone acetylation, driving neurogenesis and rapid proliferation. As intracellular Acetyl-CoA is the absolute bottleneck for histone acetylation and growth gene activation, inhibiting TKTL1 starves the cancer cell of this crucial epigenetic and structural substrate.
• Growth Factor Independence: Ectopic TKTL1 expression renders tumors resistant to serum withdrawal, bypassing apoptotic triggers caused by growth factor deprivation. TKT/TKTL1 upregulation allows cancers to maintain redox homeostasis (NADPH) and survive independently of hormonal signaling, driving resistance to endocrine therapies.
• Metastasis and Tumor Microenvironment Acidification: High TKTL1/TKT expression accelerates lactic acid production, creating an acidic tumor microenvironment. This acidosis promotes extracellular matrix degradation via the dysregulation of matrix metalloproteinases (MMPs), driving tumor invasion. OT treatment downregulates AKT-mediated PFKFB3 signaling, suppresses MMP-2 and MMP-9, and restores Tissue Inhibitors of Metalloproteinases (TIMP-1 and TIMP-2), significantly inhibiting metastatic dissemination in vitro and in vivo.
• Immunosuppression and Macrophage Polarization: Tumor-derived lactic acid paralyzes the local immune response, inhibiting TNF secretion, blunting natural killer (NK) and T cell immunosurveillance, and inducing PD-L1 expression on cancer cells. Reversing this acidosis systematically reactivates NK cells to express IFN-gamma and control tumors. Furthermore, PPP activity in macrophages fuels the UDP-glucose-STAT1-IRG1-itaconate cascade, polarizing them into an immunosuppressive M2-like phenotype. B-OT through its metabolite OT downregulates this axis, reprogramming macrophages toward a pro-inflammatory M1-like state, boosting IL-6 while decreasing IL-10, and dramatically enhancing antibody-dependent cellular phagocytosis (ADCP).
• The Lactylation Axis in Cancer: Lactate drives the epigenetic "lactylation" of histone and non-histone proteins. Lactylation of the DNA repair protein MRE11 enhances homologous recombination, promoting chemoresistance. By halting TKT-driven lactate production, B-OT cuts off the substrate required for lactylation, dismantling these epigenetic defenses.
• 3. Scientific Rationale in Virology Viruses act as obligate intracellular parasites, completely dependent on the host's metabolic machinery. B-OT acts as a host-directed therapy, targeting the specific metabolic reprogramming induced by viral infections.
• Disruption of Viral Supply Lines: Viral infection redirects host glucose into the PPP via TKT and TKTL1 to meet extreme anabolic demands. This supplies ATP for assembly, Ribose-5-Phosphate for viral RNA/DNA genome synthesis, and Acetyl-CoA/NADPH for the lipid biosynthesis needed to form viral replication complexes and envelopes. For example, dengue viruses specifically require this Warburg-like glycolytic flux for optimal replication. By inhibiting TKT/TKTL1, B-OT triggers a targeted metabolic trap, causing nucleotide and lipid starvation.
• Reversal of Viral Immune Evasion via Lactylation: Viruses hijack glycolysis to cause an infection-induced lactate surge. This lactate is utilized to lactylate the host immune sensor IFI16 at lysine 90, preventing it from recruiting DNA-PK and suppressing the induction of antiviral cytokines like IFN-beta. Lactylation of histones (e.g., H3K18la) also upregulates HSPA6, a negative regulator that blocks TRAF3/IKKε to shut down the interferon response. Furthermore, hyperlactatemia drives macrophages into an M2 state, impairing viral clearance, and is clinically correlated with severe dengue mortality. By lowering lactate production, B-OT unmasks the virus and sustains the host's innate antiviral interferon response.
• Vascular Integrity: In dengue, viral-induced MMP overproduction degrades the endothelial glycocalyx, causing plasma leakage. As previously noted, B-OT through it metabolite OT suppresses MMPs and restores TIMPs, offering a protective effect against vascular permeability.
• Validation in Viral Models: Preclinical data confirms the antiviral capacity of B-OT and OT. Pharmacological thiamine deficiency with OT increased resistance to the Lansing strain of poliomyelitis in mice. OT reversibly inhibited the growth of the psittacosis virus in tissue culture and protected cells from cytopathic effects induced by myxoviruses, including influenza and mumps. B-OT specifically inhibited SARS-CoV-2 replication in human cells in a concentration-dependent manner, showing synergy with glycolysis inhibitors.
• 4. Scientific Rationale in Mycology Thiamine antivitamins demonstrate selective antifungal activity. OT exerts potent, selective fungistatic activity against Malassezia pachydermatis and other Malassezia species (e.g., M. restricta, M. globosa), likely due to their unique cell wall structure and specific thiamine-dependent enzyme expression profiles. OT also reduces the proliferation of yeast such as Saccharomyces cerevisiae. Importantly, OT acts synergistically with standard antifungals like ketoconazole, significantly lowering the effective concentration needed to clear fungal strains, presenting a viable avenue for combination adjuvant therapies. Conversely, Candida albicans and standard dermatophytes/molds showed resistance to OT.
• 5. Scientific Rationale in Bacteriology OT functions as a potent antimetabolite against multidrug-resistant (MDR) bacterial strains, specifically Pseudomonas aeruginosa. OT inhibits ThDP-dependent enzymes like pyruvate dehydrogenase, causing severe metabolic disruption. It exhibits a low minimal inhibitory concentration (MIC50 ≈ 1.4 µM) in minimal media, retaining activity against efflux-pump mutants. OT sensitizes P. aeruginosa to standard antibiotics (e.g., tetracyclines) and non-antibiotics (e.g., 5-fluorouracil), demonstrating dramatic synergy and load reduction in murine ocular infection models. Its ability to dismantle bacterial central carbon metabolism provides a strong rationale for combination of antibacterial strategies.
• 6. Scientific Rationale in Parasitology Vitamin B1 biosynthesis and utilization are critical for parasite survival. OT targets thiamine pyrophosphokinase (TPK) in Leishmania donovani, competitively inhibiting the conversion of thiamine to its active cofactor form. This significantly impairs energy production and oxidative stress defense, demonstrating potent antiparasitic activity against both intracellular amastigotes and promastigotes without macrophage cytotoxicity. Similarly, Plasmodium falciparum (malaria) relies on scavenged thiamine; parasites overexpressing TPK become 1,700-fold more sensitive to OT, confirming lethal intracellular bioactivation. In vivo murine models confirmed that OT significantly reduces parasitemia and prolongs survival.
• 7. Safety and Selectivity Profile The broad therapeutic applicability of B-OT relies on a unique kinetic selectivity. The human TKT enzyme binds its physiological cofactor, thiamine diphosphate (ThDP), with exceptionally high, quasi-irreversible affinity via specific residues (e.g., Gln189) that lock the cofactor into the active site. Consequently, the active B-OT metabolite OTP cannot displace ThDP from pre-existing, stable holo-enzymes found in healthy tissues. Instead, OTP preferentially targets and inhibits newly synthesized apo-enzymes. Because rapidly proliferating cancer cells and virus-infected cells have extremely high rates of de novo protein turnover compared to resting cells, they are selectively starved and inhibited. This mechanism safeguards healthy cells, providing a therapeutic window.
• 8. Study Design and Cohort Progression This First-in-Human (FIH) study was conducted in a single centre and was divided into two sequential parts.
• Part 1: Single Ascending Dose (SAD): In this part, subjects received a single oral dose of B-OT. Cohorts: Up to 5 cohorts were planned with escalating doses (starting at 0.5 mg). The first two cohorts included 3 subjects each; subsequent cohorts included 6 subjects each. Sentinel Dosing: To maximize safety, each cohort began with a single sentinel subject. The remaining subjects in the cohort were dosed only after a safety observation period of at least 48 hours for the sentinel subject. Confinement: Subjects were admitted to the clinical unit on Day -1 and discharged on Day 4 (72 hours post-dose).
• Part 2: Multiple Ascending Dose (MAD): In this part, subjects received oral B-OT once daily for 7 consecutive days. Cohorts: 4 cohorts were planned with escalating doses (starting at 1 mg). Each cohort included 6 subjects. Sentinel Dosing: Similar to the SAD part, each cohort began with a sentinel subject. The remaining subjects were dosed after a safety observation period of at least 72 hours for the sentinel subject. Confinement: Subjects were admitted on Day -1 and confined through Day 8 (24 hours after the final dose) for intensive monitoring.
• Dose Escalation and Safety Review: Dose escalation between cohorts was not automatic. A Safety Review Committee (SRC) consisting of the Principal Investigator and Sponsor representatives reviewed cumulative safety, tolerability, and pharmacokinetic data from the current cohort before approving escalation to the next dose level. Stopping rules were defined for both individual subjects (e.g., occurrence of drug-related Serious Adverse Events) and for whole cohorts (e.g., if clinically relevant signs of similar nature occur in 2 or more subjects in a group).
• Pharmacokinetic and Pharmacodynamic Assessments: Serial blood samples were collected throughout the confinement periods and at follow-up visits to characterize the pharmacokinetic profile of B-OT and its metabolite oxythiamine. In the MAD part, steady-state parameters were evaluated. As an exploratory pharmacodynamic assessment, transketolase activity was measured in erythrocytes (SAD part) or white blood cells (MAD part) to determine the biological effect of the drug on its target enzyme.

• Study Type: Interventional
• Enrollment (Actual): 48
• Phase: Phase 1

Contacts and Locations

Study Locations

• Bulgaria
  • Sofia, Bulgaria
    • Diagnostics and Consultation Center (DCC) Convex EOOD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Signed and dated informed consent form.
• Subjects capable to understand the purposes and risks of the study.
• Male volunteers willing to comply with contraception requirements.
• Aged 18-60 years, inclusive.
• Healthy participants, as determined by screening assessments and Principal Investigator's judgment (absence of active/chronic disease).
• Body Mass Index (BMI) of 18-30 kg/m² inclusive.
• Male participants with female partners of childbearing potential must agree to be abstinent or use a male condom plus partner use of a contraceptive method.

Exclusion Criteria:

• Clinically relevant history of respiratory, gastrointestinal, renal, hepatic, hematological, lymphatic, neurological, cardiovascular, psychiatric, musculoskeletal, genitourinary, immunological, dermatological, endocrine, or connective tissue disorders.
• Fridericia's correction factor for QT (QTcF) > 450 ms or history of QT interval prolongation.
• Acute gastrointestinal symptoms at screening/admission.
• Any abnormal laboratory value of Grade 2 or higher considered clinically significant.
• Values ≥ 10% above upper limit of normal for ALT, AST, Alkaline Phosphatase, Creatinine, or Urea.
• Clinically relevant surgical history.
• History of relevant drug hypersensitivity, alcoholism, or drug abuse.
• Significant infection or known inflammatory process.
• Use of prescription/non-prescription medicines within 2 weeks of admission.
• Receipt of investigational drug within 30 days prior to screening.
• Use of tobacco/nicotine products within 3 months of screening.
• Positive alcohol or drug screen.
• Blood donation within 3 months prior to screening.
• Vaccinated with a Covid-19 vaccine within 2 weeks prior to screening.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Non-Randomized
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

9

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: SAD Cohort 1; Participants receive a single oral dose of 0.5 mg Benfo-oxythiamine on Day 1	Drug: Benfo-oxythiamine; Benfo-oxythiamine (B-OT) is an orally bioavailable prodrug of the thiamine antagonist oxythiamine, formulated as hard gelatin capsules (0.5 mg or 3 mg strengths) containing powder-in-capsule. Upon ingestion, it releases oxythiamine to inhibit transketolase enzymes. In the Single Ascending Dose (SAD) part, B-OT is administered as a single oral dose on Day 1. Dose levels are 0.5 mg, 1 mg, 2 mg, 3 mg, and 5 mg. In the Multiple Ascending Dose (MAD) part, B-OT is administered orally once daily for 7 consecutive days. Dose levels are 1 mg, 2 mg, 3 mg, and 5 mg. Administration occurs after an overnight fast of at least 10 hours with 240 mL of water.; Other Names: B-OT; Benfo-oxythiamine phosphate monosodium
Experimental: SAD Cohort 2; Participants receive a single oral dose of 1 mg Benfo-oxythiamine on Day 1	Drug: Benfo-oxythiamine; Benfo-oxythiamine (B-OT) is an orally bioavailable prodrug of the thiamine antagonist oxythiamine, formulated as hard gelatin capsules (0.5 mg or 3 mg strengths) containing powder-in-capsule. Upon ingestion, it releases oxythiamine to inhibit transketolase enzymes. In the Single Ascending Dose (SAD) part, B-OT is administered as a single oral dose on Day 1. Dose levels are 0.5 mg, 1 mg, 2 mg, 3 mg, and 5 mg. In the Multiple Ascending Dose (MAD) part, B-OT is administered orally once daily for 7 consecutive days. Dose levels are 1 mg, 2 mg, 3 mg, and 5 mg. Administration occurs after an overnight fast of at least 10 hours with 240 mL of water.; Other Names: B-OT; Benfo-oxythiamine phosphate monosodium
Experimental: SAD Cohort 3; Participants receive a single oral dose of 2 mg Benfo-oxythiamine on Day 1	Drug: Benfo-oxythiamine; Benfo-oxythiamine (B-OT) is an orally bioavailable prodrug of the thiamine antagonist oxythiamine, formulated as hard gelatin capsules (0.5 mg or 3 mg strengths) containing powder-in-capsule. Upon ingestion, it releases oxythiamine to inhibit transketolase enzymes. In the Single Ascending Dose (SAD) part, B-OT is administered as a single oral dose on Day 1. Dose levels are 0.5 mg, 1 mg, 2 mg, 3 mg, and 5 mg. In the Multiple Ascending Dose (MAD) part, B-OT is administered orally once daily for 7 consecutive days. Dose levels are 1 mg, 2 mg, 3 mg, and 5 mg. Administration occurs after an overnight fast of at least 10 hours with 240 mL of water.; Other Names: B-OT; Benfo-oxythiamine phosphate monosodium
Experimental: SAD Cohort 4; Participants receive a single oral dose of 3 mg Benfo-oxythiamine on Day 1	Drug: Benfo-oxythiamine; Benfo-oxythiamine (B-OT) is an orally bioavailable prodrug of the thiamine antagonist oxythiamine, formulated as hard gelatin capsules (0.5 mg or 3 mg strengths) containing powder-in-capsule. Upon ingestion, it releases oxythiamine to inhibit transketolase enzymes. In the Single Ascending Dose (SAD) part, B-OT is administered as a single oral dose on Day 1. Dose levels are 0.5 mg, 1 mg, 2 mg, 3 mg, and 5 mg. In the Multiple Ascending Dose (MAD) part, B-OT is administered orally once daily for 7 consecutive days. Dose levels are 1 mg, 2 mg, 3 mg, and 5 mg. Administration occurs after an overnight fast of at least 10 hours with 240 mL of water.; Other Names: B-OT; Benfo-oxythiamine phosphate monosodium
Experimental: SAD Cohort 5; Participants receive a single oral dose of 5 mg Benfo-oxythiamine on Day 1	Drug: Benfo-oxythiamine; Benfo-oxythiamine (B-OT) is an orally bioavailable prodrug of the thiamine antagonist oxythiamine, formulated as hard gelatin capsules (0.5 mg or 3 mg strengths) containing powder-in-capsule. Upon ingestion, it releases oxythiamine to inhibit transketolase enzymes. In the Single Ascending Dose (SAD) part, B-OT is administered as a single oral dose on Day 1. Dose levels are 0.5 mg, 1 mg, 2 mg, 3 mg, and 5 mg. In the Multiple Ascending Dose (MAD) part, B-OT is administered orally once daily for 7 consecutive days. Dose levels are 1 mg, 2 mg, 3 mg, and 5 mg. Administration occurs after an overnight fast of at least 10 hours with 240 mL of water.; Other Names: B-OT; Benfo-oxythiamine phosphate monosodium
Experimental: MAD Group 1; Participants receive 1 mg Benfo-oxythiamine orally once daily for 7 consecutive days	Drug: Benfo-oxythiamine; Benfo-oxythiamine (B-OT) is an orally bioavailable prodrug of the thiamine antagonist oxythiamine, formulated as hard gelatin capsules (0.5 mg or 3 mg strengths) containing powder-in-capsule. Upon ingestion, it releases oxythiamine to inhibit transketolase enzymes. In the Single Ascending Dose (SAD) part, B-OT is administered as a single oral dose on Day 1. Dose levels are 0.5 mg, 1 mg, 2 mg, 3 mg, and 5 mg. In the Multiple Ascending Dose (MAD) part, B-OT is administered orally once daily for 7 consecutive days. Dose levels are 1 mg, 2 mg, 3 mg, and 5 mg. Administration occurs after an overnight fast of at least 10 hours with 240 mL of water.; Other Names: B-OT; Benfo-oxythiamine phosphate monosodium
Experimental: MAD Group 2; Participants receive 2 mg Benfo-oxythiamine orally once daily for 7 consecutive days	Drug: Benfo-oxythiamine; Benfo-oxythiamine (B-OT) is an orally bioavailable prodrug of the thiamine antagonist oxythiamine, formulated as hard gelatin capsules (0.5 mg or 3 mg strengths) containing powder-in-capsule. Upon ingestion, it releases oxythiamine to inhibit transketolase enzymes. In the Single Ascending Dose (SAD) part, B-OT is administered as a single oral dose on Day 1. Dose levels are 0.5 mg, 1 mg, 2 mg, 3 mg, and 5 mg. In the Multiple Ascending Dose (MAD) part, B-OT is administered orally once daily for 7 consecutive days. Dose levels are 1 mg, 2 mg, 3 mg, and 5 mg. Administration occurs after an overnight fast of at least 10 hours with 240 mL of water.; Other Names: B-OT; Benfo-oxythiamine phosphate monosodium
Experimental: MAD Group 3; Participants receive 3 mg Benfo-oxythiamine orally once daily for 7 consecutive days	Drug: Benfo-oxythiamine; Benfo-oxythiamine (B-OT) is an orally bioavailable prodrug of the thiamine antagonist oxythiamine, formulated as hard gelatin capsules (0.5 mg or 3 mg strengths) containing powder-in-capsule. Upon ingestion, it releases oxythiamine to inhibit transketolase enzymes. In the Single Ascending Dose (SAD) part, B-OT is administered as a single oral dose on Day 1. Dose levels are 0.5 mg, 1 mg, 2 mg, 3 mg, and 5 mg. In the Multiple Ascending Dose (MAD) part, B-OT is administered orally once daily for 7 consecutive days. Dose levels are 1 mg, 2 mg, 3 mg, and 5 mg. Administration occurs after an overnight fast of at least 10 hours with 240 mL of water.; Other Names: B-OT; Benfo-oxythiamine phosphate monosodium
Experimental: MAD Group 4; Participants receive 5 mg Benfo-oxythiamine orally once daily for 7 consecutive days	Drug: Benfo-oxythiamine; Benfo-oxythiamine (B-OT) is an orally bioavailable prodrug of the thiamine antagonist oxythiamine, formulated as hard gelatin capsules (0.5 mg or 3 mg strengths) containing powder-in-capsule. Upon ingestion, it releases oxythiamine to inhibit transketolase enzymes. In the Single Ascending Dose (SAD) part, B-OT is administered as a single oral dose on Day 1. Dose levels are 0.5 mg, 1 mg, 2 mg, 3 mg, and 5 mg. In the Multiple Ascending Dose (MAD) part, B-OT is administered orally once daily for 7 consecutive days. Dose levels are 1 mg, 2 mg, 3 mg, and 5 mg. Administration occurs after an overnight fast of at least 10 hours with 240 mL of water.; Other Names: B-OT; Benfo-oxythiamine phosphate monosodium

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Participants With Treatment-Emergent Adverse Events (TEAEs)	Assessment of safety and tolerability through the collection of treatment-emergent adverse events (TEAEs). A TEAE is defined by its timing: it is any adverse event that occurs, or an existing condition that worsens in severity, after the start of study drug administration, regardless of its intensity. Unit of measure: Number of participants.	From informed consent through Day 8 (Single Ascending Dose) or Day 14 (Multiple Ascending Dose)
Number of Participants With Serious Adverse Events (SAEs)	Assessment of safety and tolerability through the collection of serious adverse events (SAEs). An SAE is defined by its severe clinical consequences: it is any event that results in death, is life-threatening, requires inpatient hospitalization, results in persistent disability, or requires medical intervention to prevent these outcomes. Unit of measure: Number of participants.	From informed consent through Day 8 (Single Ascending Dose) or Day 14 (Multiple Ascending Dose)
Number of Participants With Clinically Significant Abnormalities in Safety Laboratory Assessments	Evaluation of the number of participants experiencing clinically significant abnormal changes compared to baseline in Hematology, Biochemistry, Coagulation, and Urinalysis parameters. Unit of measure: Number of participants.	Baseline (Day -1) and up to Day 8 (Single Ascending Dose) or Day 14 (Multiple Ascending Dose)
Number of Participants With Clinically Significant Abnormalities in Vital Signs	Evaluation of the number of participants with clinically significant abnormal changes compared to baseline in vital sign measurements, including systolic and diastolic blood pressure, pulse rate, respiratory rate, and body temperature. Unit of measure: Number of participants.	Baseline (Day -1) and up to Day 8 (Single Ascending Dose) or Day 14 (Multiple Ascending Dose)
Number of Participants With Clinically Significant Abnormalities in 12-Lead Electrocardiogram (ECG)	Evaluation of the number of participants with clinically significant abnormal findings in 12-lead ECG measurements, including PR interval, QRS duration, QT interval, and QTcF (Fridericia correction) compared to baseline. Unit of measure: Number of participants.	Baseline (Day 1 pre-dose) and up to Day 8 (Single Ascending Dose) or Day 14 (Multiple Ascending Dose)
Number of Participants With Clinically Significant Abnormal Physical Examination Findings	Evaluation of the number of participants with clinically significant abnormal findings detected during physical body system assessments compared to baseline. Unit of measure: Number of participants.	Baseline (Screening) and up to Day 8 (Single Ascending Dose) or Day 14 (Multiple Ascending Dose)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Single Ascending Dose (SAD): Maximum Plasma Concentration (Cmax) of Oxythiamine	Maximum measured plasma concentration (Cmax) of the active metabolite Oxythiamine (OT) following a single oral dose administration. Unit of measure: ng/mL.	Pre-dose and at multiple time points up to 168 hours post-dose on Day 1
Single Ascending Dose (SAD): Area Under the Curve (AUC0-t) of Oxythiamine	Area under the plasma concentration-time curve from time zero to the last measurable concentration (AUC0-t) for the active metabolite Oxythiamine (OT) following a single oral dose. Unit of measure: h*ng/mL.	Pre-dose and at multiple time points up to 168 hours post-dose on Day 1
Single Ascending Dose (SAD): Area Under the Curve Infinity (AUC0-inf) of Oxythiamine	Area under the plasma concentration-time curve extrapolated to infinity (AUC0-inf) for the active metabolite Oxythiamine (OT) following a single oral dose. Unit of measure: h*ng/mL.	Pre-dose and at multiple time points up to 168 hours post-dose on Day 1
Single Ascending Dose (SAD): Terminal Elimination Half-Life (t1/2) of Oxythiamine	Apparent terminal elimination half-life (t1/2) of the active metabolite Oxythiamine (OT) following a single oral dose. Unit of measure: hours.	Pre-dose and at multiple time points up to 168 hours post-dose on Day 1
Single Ascending Dose (SAD): Apparent Body Clearance (CL/F) of Oxythiamine	Apparent total body clearance of the active metabolite Oxythiamine (OT) from plasma after single oral administration. Unit of measure: L/h.	Pre-dose and at multiple time points up to 168 hours post-dose on Day 1
Single Ascending Dose (SAD): Apparent Volume of Distribution (Vz/F) of Oxythiamine	Apparent volume of distribution of the active metabolite Oxythiamine (OT) during the terminal phase following single oral administration. Unit of measure: L.	Pre-dose and at multiple time points up to 168 hours post-dose on Day 1
Multiple Ascending Dose (MAD) Day 1: Maximum Plasma Concentration (Cmax) of Oxythiamine	Maximum measured plasma concentration (Cmax) of the active metabolite Oxythiamine (OT) following the first dose of the multiple dose regimen. Unit of measure: ng/mL.	Pre-dose and at multiple time points up to 12 hours post-dose on Day 1
Multiple Ascending Dose (MAD) Day 1: Area Under the Curve (AUC0-tau) of Oxythiamine	Area under the plasma concentration-time curve during the dosing interval (AUC0-tau) for the active metabolite Oxythiamine (OT) following the first dose. Unit of measure: h*ng/mL.	Pre-dose and at multiple time points up to 12 hours post-dose on Day 1
Multiple Ascending Dose (MAD) Day 7: Steady State Maximum Plasma Concentration (Cmax,ss) of Oxythiamine	Maximum measured plasma concentration of the active metabolite Oxythiamine (OT) at steady state following multiple daily oral doses. Unit of measure: ng/mL.	Pre-dose and at multiple time points up to 24 hours post-dose on Day 7
Multiple Ascending Dose (MAD) Day 7: Steady State Minimum Plasma Concentration (Cmin,ss) of Oxythiamine	Minimum measured plasma concentration of the active metabolite Oxythiamine (OT) at steady state following multiple daily oral doses. Unit of measure: ng/mL.	Pre-dose and at multiple time points up to 24 hours post-dose on Day 7
Multiple Ascending Dose (MAD) Day 7: Steady State Average Plasma Concentration (Cav) of Oxythiamine	Average plasma concentration of the active metabolite Oxythiamine (OT) over a dosing interval at steady state. Unit of measure: ng/mL.	Pre-dose and at multiple time points up to 24 hours post-dose on Day 7
Multiple Ascending Dose (MAD) Day 7: Steady State Area Under the Curve (AUCtau) of Oxythiamine	Area under the plasma concentration-time curve during the dosing interval at steady state (AUCtau) for the active metabolite Oxythiamine (OT). Unit of measure: h*ng/mL.	Pre-dose and at multiple time points up to 24 hours post-dose on Day 7
Multiple Ascending Dose (MAD) Day 7: Area Under the Curve Infinity (AUC0-inf) of Oxythiamine	Area under the plasma concentration-time curve extrapolated to infinity (AUC0-inf) at Day 7 for the active metabolite Oxythiamine (OT). Unit of measure: h*ng/mL.	Pre-dose on Day 7 and multiple time points up to 168 hours post-last dose
Multiple Ascending Dose (MAD) Day 7: Terminal Elimination Half-Life (t1/2) of Oxythiamine	Apparent terminal elimination half-life (t1/2) of the active metabolite Oxythiamine (OT) following the final multiple dose. Unit of measure: hours.	Pre-dose on Day 7 and multiple time points up to 168 hours post-last dose
Multiple Ascending Dose (MAD) Day 7: Steady State Apparent Body Clearance (CLss/F) of Oxythiamine	Apparent total body clearance of the active metabolite Oxythiamine (OT) from plasma at steady state. Unit of measure: L/h.	Pre-dose and at multiple time points up to 24 hours post-dose on Day 7
Multiple Ascending Dose (MAD) Day 7: Steady State Apparent Volume of Distribution (Vss/F) of Oxythiamine	Apparent volume of distribution of the active metabolite Oxythiamine (OT) at steady state. Unit of measure: L.	Pre-dose and at multiple time points up to 24 hours post-dose on Day 7
Multiple Ascending Dose (MAD) Day 7: Steady State Fluctuation (Swing) of Oxythiamine	The degree of fluctuation of the active metabolite Oxythiamine (OT) over one dosing interval at steady state, calculated as the quotient of maximum minus minimum concentration over minimum concentration. Unit of measure: %.	: Pre-dose and at multiple time points up to 24 hours post-dose on Day 7
Multiple Ascending Dose (MAD): Accumulation Ratio for Maximum Concentration (Ra Cmax) of Oxythiamine	Accumulation ratio of the active metabolite Oxythiamine (OT) based on the maximum plasma concentration, comparing steady state parameters to first dose parameters. Unit of measure: Ratio.	Day 1 and Day 7
Multiple Ascending Dose (MAD): Accumulation Ratio for Area Under the Curve (Ra AUCtau) of Oxythiamine	Accumulation ratio of the active metabolite Oxythiamine (OT) based on the Area Under the Curve during the dosing interval, comparing steady state parameters to first dose parameters. Unit of measure: Ratio.	Day 1 and Day 7
Single Ascending Dose (SAD): Time to Maximum Concentration (Tmax) of Oxythiamine	Time to reach the maximum plasma concentration (tmax) of the active metabolite Oxythiamine (OT) following a single oral dose. Unit of measure: hours.	Pre-dose and at multiple time points up to 168 hours post-dose on Day 1
Multiple Ascending Dose (MAD) Day 1: Time to Maximum Concentration (Tmax) of Oxythiamine	Time to reach maximum plasma concentration (tmax) of the active metabolite Oxythiamine (OT) following the first dose. Unit of measure: hours.	Pre-dose and at multiple time points up to 12 hours post-dose on Day 1
Multiple Ascending Dose (MAD) Day 7: Steady State Time to Maximum Concentration (Tmax,ss) of Oxythiamine	Time to reach maximum plasma concentration (tmax,ss) of the active metabolite Oxythiamine (OT) at steady state. Unit of measure: hours.	Pre-dose and at multiple time points up to 24 hours post-dose on Day 7
Multiple Ascending Dose (MAD) Day 7: Trough Concentration (Ctrough) of Oxythiamine	Plasma concentration of the active metabolite Oxythiamine (OT) measured immediately before the next dose to assess steady state. Unit of measure: ng/mL.	Assessed at Pre-dose on Days 2, 3, 4, 5, 6, and 7, Day 7 reported.
Multiple Ascending Dose (MAD) Day 7: Peak-Trough Fluctuation (PTF) of Oxythiamine	Peak-trough fluctuation percentage of the active metabolite Oxythiamine (OT) at steady state, calculated over a complete dosing interval as the difference between maximum and minimum concentration divided by the average concentration. Unit of measure: %.	Pre-dose and at multiple time points up to 24 hours post-dose on Day 7

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Exploratory: Transketolase Activity	Transketolase activity measured in erythrocytes (for the Single Ascending Dose part) and white blood cells (for the Multiple Ascending Dose part) to evaluate the pharmacodynamics of the drug on its target enzyme. Data reported as not analyzed due to assay performance issues. Unit of measure: Not Applicable (Data not analyzed).	Pre-dose and multiple time points up to Day 8 (Single Ascending Dose) or Day 14 (Multiple Ascending Dose)

Collaborators and Investigators

• Sponsor: Benfovir AG

Publications and helpful links

General Publications

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Study record dates

Study Major Dates

• Study Start (Actual): March 1, 2022
• Primary Completion (Actual): November 21, 2022
• Study Completion (Actual): November 21, 2022

Study Registration Dates

• First Submitted: February 18, 2026
• First Submitted That Met QC Criteria: February 26, 2026
• First Posted (Actual): March 5, 2026

Study Record Updates

• Last Update Posted (Actual): April 20, 2026
• Last Update Submitted That Met QC Criteria: March 27, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: SARS-CoV-2; Healthy volunteers; Safety; Pharmacokinetics; COVID-19; Phase I; Oncology; Solid Tumors; Prodrug; Single Ascending Dose (SAD); Multiple Ascending Dose (MAD); First-in-human (FIH); Cancer metabolism; Benfo-oxythiamine (B-OT); Oxythiamine; Transketolase Inhibitor; Thiamine antagonist; Metabolic inhibitor; Metabolic Targets; TKTL1; Transketolase
• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Respiratory Tract Infections; Infections; RNA Virus Infections; Virus Diseases; Respiratory Tract Diseases; Neurobehavioral Manifestations; Lung Diseases; Pneumonia, Viral; Pneumonia; Coronavirus Infections; Coronaviridae Infections; Nidovirales Infections; Memory Disorders; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; COVID-19; Neoplasms; Korsakoff Syndrome
• Other Study ID Numbers: BV-01-101; 2021-005616-60 (EudraCT Number)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared. All records identifying the subject will be kept confidential and will not be made publicly available.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No