This adaptor comprises a tubular body having a proximal region and a distal region, the proximal region configured to engage a distal tip of said drug delivery device and the distal region being configured to be connected to the connector. The distal region has a distal end delimiting a distal opening so as to permit introduction of the connector inside the distal region. The distal end is configured to be clamped to the connector when said connector is introduced inside the tubular body. The distal end comprises a deformable element having a free end which is configured to deform towards the proximal region when the connector is introduced inside the tubular body.
