Stephen Silberstein, MD: The first antibody on the market was an antibody against the CGRP receptor, erenumab, or Aimovig. The second antibody to be approved by the FDA was against CGRP, fremanezumab, or Ajovy. The third antibody to be approved by the FDA is galcanezumab, which is again against the CGRP receptor. The last antibody under development is an antibody against the CGRP itself, and it does not yet have a brand name.
The current CGRP antibodies are indicated for the treatment of migraine in adults. There are studies being done for cluster headache and for posttraumatic headache, but that’s the current indication. How do they differ? The antibody called Aimovig is against the CGRP receptor. That is where CGRP does its business. The other antibodies are against CGRP itself. All drugs are effective. The side effect profiles are slightly different, and the weights at which you can inject them are different. But we’re really excited we have 3, and possibly a fourth antibody, for the preventative treatment of migraine.
In this day and age, what we use in clinical practice more often than not depends on the insurance companies. If the insurance companies make the drug available, we’ll use it. If they don’t make it available, it becomes very difficult to use it. Since the first antibody, erenumab, came out, we used it first. And it was about 4 to 5 months until we got the second antibody. So we have the most experience with erenumab and the second antibody, fremanezumab. And the third antibody we have less experience with just because of the sequence. I believe we have over 1000 patients on the antibodies at this time. And here’s my bias: Just like in the trials, they work half the time. When they work, they’re really great, and many of these patients have failed everything else.
The dose of erenumab, or Aimovig, is either 70 or 140 units or mg per month. I pick the higher dose because the price is the same. And if you think about it, there’s no risk in giving a higher dose and there’s always chance you’ll get a better response with monthly 140. The second drug to be approved was fremanezumab, or Ajovy, and the doses are 225 mg every month or a triple dose every 3 months. Many patients don’t like to self-inject and prefer less-frequent dosing, so in most of our patients, we tend to be using the triple dose every 3 months. The third antibody is again galcanezumab, which is given on a monthly basis. These antibodies come in prefilled syringes, so they’re given at home by the patient.
If you’ve never used a monoclonal antibody before, there’s a lot of material available. There are papers that I and my colleagues have written. There’s information online. The biggest thing you need to know, regarding those things you hear about on television every night about monoclonal antibodies causing every bad disease known to mankind, is that antibodies against CGRP have minimal, if no, side effects. The only side effect we’ve seen is a little bit of constipation. That’s what you need to know. There are no other major issue except for constipation. There are no more side effects than there are with placebo injections. So they’re safe, they’re effective, they’re tolerated, and they’re easy to use.