Pimodivir Plus Standard Care in High-Risk Influenza A Patients: Phase 3 Results

Overview

Two phase 3 randomized controlled trials assessed pimodivir combined with standard of care (SoC) versus placebo plus SoC in hospitalized and high-risk outpatient adolescents and adults with influenza A. Pimodivir showed no clinical benefit in hospitalized patients but significantly shortened time to resolution of symptoms in high-risk outpatients.

Background

Influenza A causes substantial morbidity and mortality, with limited effective antiviral options especially in hospitalized patients. Resistance to existing antivirals like oseltamivir and baloxavir underscores the need for novel treatments. Pimodivir, a PB2 polymerase inhibitor, has shown promise in earlier phase studies for both hospitalized and outpatient influenza A patients. These phase 3 trials evaluated pimodivir's efficacy and safety when added to investigator-chosen SoC, primarily oseltamivir.

Data Highlights

Key Findings

• Pimodivir plus SoC did not improve Hospital Recovery Scale outcomes at day 6 in hospitalized influenza A patients.
• In high-risk outpatients, pimodivir plus SoC significantly shortened median time to resolution of influenza symptoms by approximately 12.5 hours compared to placebo plus SoC.
• Most patients received oseltamivir as part of SoC in both studies.
• Pimodivir was well tolerated with a safety profile consistent with previous studies.
• The hospital study enrolled patients with hypoxia (SpO2 <94%) and elevated NEWS2 scores, reflecting severe illness.
• Outpatients were enrolled within 72 hours of symptom onset and had moderate or worse respiratory and systemic symptoms.

Clinical Implications

Pimodivir added to standard antiviral therapy does not provide additional clinical benefit in hospitalized patients with influenza A. However, in high-risk outpatients, pimodivir may accelerate symptom resolution, potentially reducing disease burden. These findings support consideration of pimodivir use in outpatient settings but not in hospitalized patients.

Conclusion

Pimodivir combined with standard care failed to improve recovery in hospitalized influenza A patients but demonstrated a modest clinical benefit by shortening symptom duration in high-risk outpatients. Further research may clarify its role in outpatient influenza management.

References

1. Study NCT03376321 and NCT03381196 -- Pimodivir Phase 3 Trials