The targeted anti-CGRP approach, which can be used by patients with liver or kidney disease,results in decreased toxicity and minimal drug interactions. Long half-lives allow for monthly or quarterly injections, possibly resulting in increased compliance.28 Dose titration is not needed, allowing for more rapid symptom management. The large molecular size of a mAb limits its transfer across the blood-brain barrier, making central nervous system adverse effects unlikely.28 Despite the compelling mAb pharmacologic properties, their use may be limited by a lack of long-term safety data and the need for parenteral administration. Although immunogenicity—the development of neutralizing antibodies—can limit long-term tolerability or efficacy of mAbs generally,26,28 anti-CGRP mAbs were engineered to minimally activate the immune system and have not been associated with immune suppression, opportunistic infections, malignancies, or decreased efficacy.28
Unlike triptans and ergotamine derivatives, gepants do not constrict blood vessels and may have a unique role in patients with contraindications to triptans.
A pooled meta-analysis including 4 trials (3166 patients) found that CGRP mAbs compared with placebo significantly improved patient response rates, defined as at least a 50% and 75% reduction in monthly headache/migraine days from baseline to Weeks 9 to 12.48 Another meta-analysis including 8 trials (2292 patients) found a significant reduction from baseline in monthly migraine days and monthly acute migraine medication consumption among patients taking CGRP mAbs compared with those taking placebo.49 Open-label extension studies have shown progressive and cumulative benefits in individuals who respond to anti-CGRP mAbs. Therefore, several treatment cycles may be necessary to determine overall efficacy of therapy.10,28
Cost initially can be a barrier.Insurance companies often require step therapy before agreeing to cover mAb therapy, which aligns with the 2019 AHS position statement.10 Due to differences in insurance coverage, out-of-pocket expenses can vary greatly. However, options are available through online manufacturer assistance to reduce cost, making it comparable to other migraine treatments. Safety and efficacy studies of anti-CGRP mAbs use in pregnant individuals are limited. At this time, they should not be prescribed for those who are pregnant, planning to become pregnant, or breastfeeding. Counsel nonpregnant patients on appropriate contraception while using a mAb due to possible teratogenicity and negative pregnancy outcomes.28,50
When combination treatment may be appropriate
Monotherapy is the usual approach to preventing migraine due to advantages of efficacy, simplified regimens, lower cost, and reduced adverse effects.51 However, if a patient does not benefit from monotherapy even after trying dose titrations as tolerated or switching therapies, trying complementary combination therapy is appropriate. Despite a shortage of clinical trials supporting the use of 2 or more preventive medications with different mechanisms of action, this strategy is used clinically.10 Consider combination therapy in those with refractory disease, partial responses, or intolerance to recommended doses.52 Articles reporting on case study reviewshave rationalized the combined use of onabotulinumtoxinA and anti-CGRP mAbs, noting better migraine control.51,53 The 2019 AHS position statement recommends adding a mAb to an existing preventive treatment regimen with no other changes until mAb effectiveness is determined, as the risk for drug interactions on dual therapy is low.10 Safety and efficacy also have been demonstrated with the combination of preventive anti-CGRP mAbs and acute treatment with gepants as needed.54
Monoclonal antibodies are highly efficacious options for those who cannot tolerate or achieve only minimal efficacy with traditional preventive therapies.
Overall, gepants and mAbs are as effective as traditional acute and preventive treatments for migraine, and they cause fewer adverse effects and often allow a more simplified regimen. Gepants and mAbs are viable options in the primary care setting. Due to limited long-term data and high cost, however, they routinely are used for refractory migraine rather than as first-line agents. These therapies are especially favorable options for patients when traditional migraine therapies yield inadequate efficacy, cause intolerable adverse effects, are contraindicated, or introduce the risk for medication interactions.
CORRESPONDENCE Emily Peterson, PharmD, BCACP, 3640 Middlebury Road, Iowa City, IA 52242; Emily-a-peterson@uiowa.edu
