Hi , are you sure they didn't mean using Ampyra with Kesimpta? You really wouldn't stop Kesimpta in order to take ampyra. Kesimpta is a disease-modifying drug used to slow MS progression whereas ampyra is used solely to help with walking (it won't help fight the disease as Kesimpta does). If they are adding it to use along Kesimpta, it is worth a try (I tried it, but it didn't help me, it does help others though).
You can learn a little more about Amypra here: https://multiplesclerosis.net/living-with-ms/medications-symptoms