Complex Clinical Trials

Complex Clinical Trials (e.g. Umbrella-, Basket- Platform design)

There are differences between complex clinical trials and conventional clinical trials, particularly with regards to clinical trial applications (CTAs) and requests for substantial amendments. The Clinical Trials Facilitation and Coordination Group (CTFG) highlights these differences in the Recommendation Paper on the Initiation and Conduct of Complex Clinical Trials published 12.02.2019. These recommendations should be read in conjunction with current legislation regulating clinical trials.
For the assessment of clinical trial applications of studies with complex designs, Swissmedic relies on the recommendation paper of the CTFG.

Swissmedic suggests you to read the publication of the CTFG and asks you to communicate with us according to the language used in this publication.

Before submitting a clinical trial with a complex design,

you can request a preliminary evaluation of the project. Swissmedic will decide on a case-by-case basis whether or not the project is suitable for a complex clinical trial and whether or not Swissmedic will accept the project as a single trial.

Here is what to do:

Please send us the following documents by email (to

a. E-mail subject or cover letter "Pre-assessment clinical trial with complex design".
b. Protocol overview
c. Study flow diagram showing elements of master protocol, sub-protocol, indication(s), IMPs, and trial design used. Select Umbrella, Basket, or Platform design options for this purpose.

Submission of a Clinical Trial Application (CTA) for a clinical trial with complex design

Scientific advice:

The Swissmedic Clinical Trials division cannot provide any scientific advice on study design, statistics or applications for marketing authorisation. It is, however, possible to discuss issues relating to the submission of a complex clinical trial in a conference call. If you would like a telephone conference, please already specify this in the above-mentioned "Pre-assessment – clinical trial with complex design" e-mail. You will then receive an invitation with various suggestions for calling times.

Questions regarding complex clinical trials with transplant products, gene therapy, and/or GMOs should be addressed directly to the ATMP department.

Last modification 03.05.2022

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