Last reviewed 2026-04-23 · How we verify

Placebo to Baloxavir Marboxil

Placebo to Baloxavir Marboxil is a Cap-dependent endonuclease inhibitor Small molecule drug developed by Shionogi. It is currently in Phase 3 development for Acute uncomplicated influenza (treatment), Influenza prophylaxis (prevention).

Baloxavir marboxil is a cap-dependent endonuclease inhibitor that blocks influenza virus polymerase, preventing viral mRNA synthesis and replication.

Baloxavir marboxil is a cap-dependent endonuclease inhibitor that blocks influenza virus polymerase, preventing viral mRNA synthesis and replication. Used for Acute uncomplicated influenza (treatment), Influenza prophylaxis (prevention).

At a glance

Mechanism of action

Baloxavir marboxil is a prodrug that is converted to its active form, baloxavir, which selectively inhibits the influenza virus cap-dependent endonuclease (PA endonuclease). This enzyme is essential for the viral polymerase complex to cleave host pre-mRNA caps, which are then used to prime viral mRNA synthesis. By blocking this step, baloxavir prevents the generation of viral mRNA and halts influenza virus replication at an early stage of infection.

Approved indications

• Acute uncomplicated influenza (treatment)
• Influenza prophylaxis (prevention)

Common side effects

• Headache
• Diarrhea
• Nausea
• Nasopharyngitis

Key clinical trials

• Safety and Efficacy of ADC189 in Children 2-11 Years Old With Influenza (PHASE3)
• Study to Assess the Efficacy of Baloxavir Marboxil Versus Placebo to Reduce Onward Transmission of Influenza A or B in Households (PHASE3)
• Baloxavir in Combination With Oseltamivir in Allogenic Bone Marrow Transplant Recipients With Influenza (PHASE2, PHASE3)
• Efficacy of Baloxavir Against Influenza in Hospitalized Patients: the INFLUENT Study (INpatients InFLUENza Treatment) (PHASE3)
• Study to Assess Efficacy and Safety of Baloxavir Marboxil In Combination With Standard-of-Care Neuraminidase Inhibitor In Hospitalized Participants With Severe Influenza (PHASE3)
• Study to Assess the Safety, Pharmacokinetics, and Efficacy of Baloxavir Marboxil in Healthy Pediatric Participants With Influenza-Like Symptoms (PHASE3)
• Study of S-033188 (Baloxavir Marboxil) Compared With Placebo or Oseltamivir in Patients With Influenza at High Risk of Influenza Complications (PHASE3)
• A Study of S-033188 (Baloxavir Marboxil) Compared With Placebo or Oseltamivir in Otherwise Healthy Patients With Influenza (PHASE3)

Primary sources

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Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

• Placebo to Baloxavir Marboxil CI brief — competitive landscape report
• Placebo to Baloxavir Marboxil updates RSS · CI watch RSS
• Shionogi portfolio CI

Frequently asked questions about Placebo to Baloxavir Marboxil

Related

• Drug class: All Cap-dependent endonuclease inhibitor drugs
• Target: All drugs targeting Influenza virus PA endonuclease (cap-dependent endonuclease)
• Manufacturer: Shionogi — full pipeline
• Therapeutic area: All drugs in Infectious Disease / Virology
• Indication: Drugs for Acute uncomplicated influenza (treatment)
• Indication: Drugs for Influenza prophylaxis (prevention)
• Compare: Placebo to Baloxavir Marboxil vs similar drugs
• Pricing: Placebo to Baloxavir Marboxil cost, discount & access