Analysis: 3 Months of Treatment Sufficient to Evaluate Erenumab Response

Findings of a post hoc analysis of a phase 3 trial support guidelines recommending at least 3 months following the initiation of erenumab for migraine prevention before the assessment of response. Results were published in The Journal of Head and Face Pain.

Erenumab is a fully human monoclonal antibody, approved in 2018, that is administered monthly via self-injection of a 70- or 140-mg dose. It works to block the calcitonin gene-related peptide (CGRP) receptor, which is believed to play a crucial role in the pathophysiology of migraine.

“When initiating long-term treatment for a chronic condition, patients and clinicians may question how quickly a patient can expect relief and whether relief will be sustained,” authors explained, while clinicians must also decide whether to continue treatment or switch to an alternative in those who do not report early robust responses.

Results of the phase 3 STRIVE trial showed erenumab was effective and well-tolerated in patients with episodic migraine. In the 6-month double-blind treatment phase, “many patients achieved significant reductions in monthly migraine days (MMDs) within the first month of treatment and some within the first week; however, some patients took longer to experience a response,” they noted.

In the current post hoc analyses, researchers assessed at least 50% reduction in MMD as a primary threshold for response for time to first monthly response and sustainability of response. Patients were assessed based on data they entered into an electronic diary, and all those included must have demonstrated at least 80% compliance in using the tool during the baseline phase.

A total of 312 and 318 patients enrolled in the erenumab 70- and 140-mg arms, respectively, were included in the analysis. The majority of participants were White females.

Data showed:

• During the 6-month treatment period, 73.7% (230/312) and 79.6% (253/318) of patients in the erenumab 70 mg and 140 mg groups, respectively, achieved a response in at least 1 month.
• In this group of responders, at least half reached first monthly response (first month with at least 50% reduction from baseline in MMDs) by month 2 and at least 75% of them by month 3.
• The remainder responded in months 4 to 6; of patients in the erenumab 70 and 140 mg groups, 35.3% (110/312) and 41.8% (133/318), respectively, responded over months 1 to 3 (mean response over first 3 months).
• Of these patients, 81.8% (90/110) and 81.9% (109/133) maintained this response over months 4 to 6 (mean response over last 3 months) in the 70 and 140 mg groups, respectively.

Researchers also found “many patients who did not achieve an initial response (≥50% reduction from baseline in MMDs during month 1) responded later with continued treatment, with approximately one-half or more of initial nonresponders responding by months 4–6.”

The American Headache Society and European Headache Federation recommend at least 3 months of treatment with erenumab prior to evaluating a patient’s response, they added. Results indicate that efficacy onset can occur rapidly following initiation and that improvement can be maintained during the 6-month treatment period.

However, headache and migraine days are also subject to fluctuation and individual pharmacokinetic differences among patients could contribute to variable response times. More research is warranted to better understand differential patient response.

Because the analysis was based on a 6-month window, investigators were unable to draw conclusions beyond that timeframe. Results are also limited to those with episodic migraine and severity and functional disability were mot measured.

“In this analysis, monthly response, once achieved, generally was maintained with continued treatment,” authors concluded. “In patients with less than robust early response to erenumab, a subsequent response may be possible, but the probability of response diminished with the length of time without a response and with lower levels of initial MMD reduction.”

Reference

McAllister PJ, Turner I, Reuter U, et al. Timing and durability of response to erenumab in patients with episodic migraine. Headache. Published online November 28, 2021. doi:10.1111/head.14233