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Agile CST-8


Seamless Phase I/IIa Platform for the Rapid Evaluation of Candidates for COVID-19 treatment

Candidate-Specific Trial 8 (CST-8): A Randomized, Multicentre, Seamless, Adaptive, Phase I Platform Study to Determine the Recommended Phase II dose and Evaluate the Safety and Efficacy of combination of Molnupiravir and Paxlovid® for the Treatment of COVID-19.


This study is an open-label, randomised, Phase I dose de-escalation trial to assess the safety and tolerability of drug combination of molnupiravir and Paxlovid® on SARS-CoV-2.


Primary Objectives:

  • To determine the safety and tolerability of dose combinations of molnupiravir and Paxlovid®

Secondary Objectives:

  • Establish feasibility for the combination to be trialed in a larger late phase platform
  • To evaluate preliminary evidence of virological efficacy
  • To characterise the pharmacology of each drug within the combination

 Exploratory Objectives:

  • To characterise pharmacology of Paxlovid® (i.e.nirmatrelvir and ritonavir) in tears, saliva and nasal secretions
  • To characterise genetic variability in SARS-CoV-2 before and during treatment
  • To evaluate changes in culturable virus on treatment

Trial Design

Open-label 2:1 randomised controlled Phase I de-escalation study of molnupiravir + Paxlovid® versus standard of care alone.

Phase I will be open label assessing de-escalating doses of molnupiravir with a fixed dose of Paxlovid® compared with Standard of Care (SoC). Patients in phase I will be recruited in cohorts of 6 (randomised to molnupiravir + Paxlovid®: SoC in 2:1 allocation ratio), with review of safety and tolerability between cohorts. 

Trial Status



Adult out-patients (≥18 years) with laboratory confirmed COVID-19, who are within 5 days of symptom onset

Senior Trial Manager:

Emma Knox        

Trial Manager:

Calley Middleton

Trial Coordinator:

Jan Dixon

Data Manager:

Emma Tilt

Clinical Data Coordinator:

Oliver Edwards

Contact Information:

Email: [email protected]

SAE reporting: 

Email: [email protected]

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