Fundamental Analysis Discussion Only (IXC Thread), page-13

Here are some thoughts:

The hypothesised Mechanism of Action for Exenatide is a reduction in ICP by way of a reduction of CSF production, with ICP the root cause of the symptoms experienced by IIH patients such as Headaches/Vision loss (Reducing these symptoms with Exenatide via aiding the underlying condition)

While the MOA for Erenumab is as a temporary reduction in migraines by blocking the CGRP protein that is associated with migraines, but the core root issue in the raised ICP persists/remains for IIH patients, alongside the overproduction of CSF, resulting in the reoccuring headaches/optical nerve pressure/vision loss etc. (Masking the symptoms, but not aiding the underlying condition).

Intentionally extreme example, but the way I see it is kind of like suppressing your appetite while you're starving by taking an injection to reduce hunger. Sure, the symptom of being hungry is alleviated, but the core root issue of hunger (of raised ICP) is progressively getting worse. Instead, you could have a meal (take an injection that reduces ICP; hypothesised MOA by taking Exenatide) and the core root issue of the symptoms of hunger (ICP) are reduced.

Furthermore, there has been no large randomised trials for Erenumab, and it isnt approved for IIH, so it wouldnt be subsidised by insurance plans. It seems to have data only for patients without vision issues (Optical nerve swelling; papilloedema) while ~90% of all IIH patients have this. Exenatide is targeting this group of IIH patients.

If I were a patient, and if approved with hypothesised MOA validated, I would prefer Exenatide.

Hope that helps.