Clinical Scorecard: Antibody Response Dynamics to SARS-CoV-2 and Clinical Outcomes Following Sotrovimab Prophylaxis in Early Post-Allogeneic Hematopoietic Stem Cell Transplantation

At a Glance

Key Highlights

• Sotrovimab administration early post-alloHCT increased and sustained anti-S/RBD total immunoglobulin levels and neutralizing antibody titers against SARS-CoV-2 variants including Omicron BA.1 and BA.2.
• Prior SARS-CoV-2 vaccination or infection before alloHCT correlated with higher baseline neutralizing antibody activity.
• Breakthrough SARS-CoV-2 infections occurred in 19.4% of patients despite sotrovimab prophylaxis, mostly asymptomatic; sotrovimab was well tolerated with minimal adverse events.

Guideline-Based Recommendations

Diagnosis

• Routine SARS-CoV-2 PCR testing on days 30 and 60 post-sotrovimab administration and upon symptom onset.

Management

• Administer sotrovimab 500 mg intravenously as pre-exposure prophylaxis within first 3 months after alloHCT to bridge period before effective vaccination.
• Consider repeat dosing if anti-S/RBD total Ig levels remain low.

Monitoring & Follow-up

• Monitor anti-S/RBD total immunoglobulin levels and neutralizing antibody titers at baseline, day 7, 30, and 60 post-sotrovimab.
• Observe patients clinically for breakthrough infections and adverse events.

Risks

• Potential for breakthrough SARS-CoV-2 infection despite prophylaxis, though mostly mild or asymptomatic.
• Low incidence of transient fever and rash as adverse events post-sotrovimab.

Patient & Prescribing Data

36 alloHCT recipients receiving sotrovimab within 17–80 days post-transplant, majority previously vaccinated or infected with SARS-CoV-2.

Sotrovimab induced rapid increase in neutralizing antibodies peaking at day 7, sustained through day 60; well tolerated with low adverse event rate; breakthrough infections occurred but were mostly asymptomatic.

Clinical Best Practices

• Administer monoclonal antibody prophylaxis early post-alloHCT to provide immediate passive immunity against SARS-CoV-2.
• Perform regular serologic and PCR monitoring to assess antibody dynamics and detect breakthrough infections.
• Recognize prior vaccination or infection history as beneficial for baseline neutralizing antibody levels.
• Maintain vigilant clinical follow-up given risk of breakthrough infections despite prophylaxis.

References

• Vaccination recommendations post-alloHCT
• PROVENT study on tixagevimab/cilgavimab prophylaxis
• In vitro neutralization activity of sotrovimab