PROCYSBI® is Approved: New Product Supported by Cytel Adaptive Trial and Data Analytics, Medical Writing and CDISC Migration Services

Sponsor's Challenge

California-based specialty developer Raptor Pharmaceutical’s first drug to Phase 3 is for a rare, debilitating metabolic disease that severely affects 2,000 children: Nephropathic Cystinosis.  Raptor completes planning for six total pivotal studies at sites in North and France to support FDA and EMA NDAs.

Then the unexpected occurs. Shortly before was scheduled the FDA issues a Special Protocol Assessment (SPA).  This further complicates the final development of an already challenging orphan program.

In response, Raptor asks Cytel to create a non-inferiority design and analysis plan as the SPA specified.  The FDA allows the sponsor to proceed with the revised approach, with the added provision for a sample size re-estimation (SSR) adaptation.  The new Cytel design is intended to provide sufficient information to support a blinded interim analysis to determine if additional patients would be beneficial. The same approach is also deemed suitable for the EMA as well.


The FDA and the EMA submissions were made as their plan intended - their original plan, prior to receiving the SPA. In 2013, Raptor’s first product, PROCYSBI®, was approved and is marketed throughout the Americas and and Pan-Europe.

Raptor achieved orphan drug development success and is now realizing the benefits of extended patent.

Adaptive Trial Milestone

PROCYSBI® is among the very first treatments approved following an adaptive sample size re-estimation study.

Beyond Statistical Consulting

During the initial statistical consulting, Raptor becomes familiar with Cytel’s clinical data management capabilities, and further engages Cytel to help centralize their biometrics needs, including:

  • CDISC CRF Annotation
  • CDISC Migration
  • ADaM Development
  • ISS SAP & Programming
  • ISE Programming
  • Defining XML and PDFs
  • ISS/ISE Medical Writing
  • Final CSR for NDA

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