A Clinical Trial to Investigate Long-term Safety, Tolerability, and Efficacy of Weekly Subcutaneous Doses With TransCon CNP in Children and Adolescents With Achondroplasia

This study is specifically for children and teenagers aged 3 to 15 years old who have achondroplasia. Crucially, you must have already taken part in a previous clinical trial for TransCon CNP and completed it successfully. This means the researchers already have some information about how you responded to the treatment.

Your parent or legal guardian must agree in writing for you to take part, and they need to be able to give the weekly injections under the skin and follow the study rules. You should also be in good health, according to the doctors' checks, and not have any other medical conditions that would make it unsafe or difficult to take part.

There are also some reasons why someone might not be able to join. For example, if you are allergic to the medicine or its ingredients, or if you are taking other prescription medicines (apart from TransCon CNP). Female participants who could get pregnant must use effective contraception during and for a period after the study. Your vitamin D levels will also be checked to make sure they are not too low.

If you join this study, you will continue to receive the TransCon CNP medicine as a weekly injection under the skin. Your parent or guardian will be trained on how to give these injections at home. The dose will be 100 micrograms of CNP per kilogram of your body weight each week.

You will have regular check-ups at the clinic, usually every 12 to 14 weeks. These visits will involve various assessments, including physical examinations, blood tests, and X-rays to check your bone growth. The purpose of these tests is to monitor your health, look for any side effects, and see how well the treatment is working.

Your participation will continue until your leg bones (femur and tibia) have stopped growing and the growth plates have closed. This will be confirmed by X-rays. For girls, this is generally around 16 years of age, and for boys, around 18 years of age. If your bones haven't finished growing by these ages, you may continue treatment until they do. The total length of time you are in the study will therefore be different for everyone.