What is galcanezumab (Emgality)?

Galcanezumab (Emgality): Overview

Galcanezumab is a humanized IgG4 monoclonal antibody that binds to the calcitonin gene-related peptide (CGRP) ligand, preventing it from binding to its receptor, and is FDA-approved for the preventive treatment of migraine and episodic cluster headache in adults. 1

Mechanism of Action

• Galcanezumab specifically targets and binds to the CGRP ligand, blocking its biological activity by preventing receptor binding 1
• CGRP is a potent vasodilator implicated in nociceptive transmission and plays a critical role in migraine pathophysiology and trigeminal nerve pain and inflammation 2, 3
• The drug is produced in Chinese Hamster Ovary (CHO) cells by recombinant DNA technology and has a molecular weight of approximately 147 kDa 1

FDA-Approved Indications

Migraine Prevention

• Approved for preventive treatment of both episodic and chronic migraine in adults 1
• For migraine prevention, the dosing regimen is a 240 mg loading dose (two 120 mg injections) followed by 120 mg monthly subcutaneous injections 1

Episodic Cluster Headache

• Approved for treatment of episodic cluster headache in adults 1
• For episodic cluster headache, the dose is 300 mg (three 100 mg injections) given monthly at the start of a cluster period and continued until the end of the cluster period 1

Clinical Guideline Positioning

American College of Physicians (2025)

• ACP recommends galcanezumab as second-line therapy for episodic migraine prevention in nonpregnant adults who do not tolerate or inadequately respond to first-line agents (beta-blockers, valproate, venlafaxine, or amitriptyline) 2
• This recommendation is based primarily on economic evidence and patient preferences, as CGRP monoclonal antibodies are substantially more costly than first-line alternatives, despite showing low-certainty evidence of small benefits in reducing migraine frequency compared to some alternatives 2
• CGRP-mAbs may reduce migraine frequency by 0.80 fewer days per month and acute medication intake by 1.02 fewer days per month compared to topiramate, with probably fewer discontinuations due to adverse events (162 fewer events per 1000 treated people) 2

VA/DoD Guidelines (2024)

• VA/DoD suggests galcanezumab for prevention of episodic cluster headache (weak recommendation) 2
• VA/DoD suggests against galcanezumab for prevention of chronic cluster headache (weak recommendation) 2
• The guidelines note that monoclonal antibodies targeting CGRP either block the peptide from binding to the receptor (galcanezumab, fremanezumab, eptinezumab) or block the receptor-binding site (erenumab) 2

Pharmacokinetics

• Subcutaneous administration with time to maximum concentration of approximately 5 days 1
• Elimination half-life of 27 days, allowing for monthly dosing 1
• Linear pharmacokinetics with exposure increasing proportionally between 1-600 mg doses 1
• A 240 mg loading dose achieves steady-state concentration after the first dose; a 300 mg monthly dose achieves steady-state after the fourth dose 1
• Apparent volume of distribution is 7.3 L, and apparent clearance is 0.008 L/h 1
• Pharmacokinetics are not affected by age, sex, race, weight, or migraine subtype 1

Efficacy Evidence

Migraine Prevention

• Phase 3 trials (EVOLVE-1, EVOLVE-2, REGAIN) demonstrated significant reduction in monthly migraine headache days in both episodic and chronic migraine over 3-6 months 4, 5
• Greater proportions of patients achieved ≥50%, ≥75%, and 100% response rates compared to placebo 4
• Benefits on reducing migraine days and improving quality of life were sustained for up to 12 months in open-label extension studies 4, 5
• A 2025 meta-analysis showed overall efficacy of 76.0% (95% CI 0.67-0.85) in reducing cluster headache attacks by at least 50% 6

Cluster Headache

• In episodic cluster headache, galcanezumab significantly reduced weekly frequency of attacks during weeks 1-3, though results converged with placebo during weeks 4-8 5
• Preclinical studies demonstrate that galcanezumab reduces trigeminal nociception by up to 73% and dampens both noxious and non-noxious sensory stimuli 7

Safety Profile

Common Adverse Events

• Treatment-emergent adverse events (TEAEs) occurred in 48% of patients overall, with most being mild 6
• Most common TEAEs include nasopharyngitis, local injection site pain, and local injection site swelling 2, 6
• TEAEs were considerably higher with 300 mg dosing (80%) compared to 240 mg dosing (28%) 6
• No serious adverse events or treatment discontinuations were reported in recent real-world dual-CGRP therapy studies 8

Warnings and Precautions

• Hypersensitivity reactions can occur; patients should seek immediate medical attention if symptoms develop 1
• Hypertension can develop or worsen; patients should contact their healthcare provider if blood pressure elevates 1
• Raynaud's phenomenon can develop or worsen; discontinue if signs or symptoms occur 1

Pregnancy and Lactation

• No adequate data in pregnant women; estimated background risk of major birth defects (2.2-2.9%) and miscarriage (17%) in women with migraine are similar to the general population 1
• No data on presence in human milk; developmental and health benefits of breastfeeding should be considered along with maternal clinical need 1
• A pregnancy exposure registry is available at 1-833-464-4724 or www.migrainepregnancyregistry.com 1

Administration and Storage

• Supplied as single-dose prefilled pen (120 mg) or prefilled syringe (100 mg or 120 mg) for subcutaneous injection 1
• Injection sites include abdomen, thigh, back of upper arm, or buttocks 1
• Store refrigerated at 2°C to 8°C (36°F to 46°F) in original carton to protect from light 1
• May be stored at room temperature up to 30°C (86°F) for up to 7 days; do not return to refrigerator once removed 1

Clinical Considerations

• Patients probably prefer oral treatments over injectables like CGRP monoclonal antibodies (moderate-certainty evidence) 2
• The median annual wholesale acquisition cost for CGRP-mAbs is substantially higher than first-line preventive agents like beta-blockers, amitriptyline, valproate, and topiramate 2
• Adherence is crucial as improvement may occur gradually, with effects becoming apparent after the first few weeks of treatment 2
• Dual-CGRP therapy (combining galcanezumab with small-molecule CGRP antagonists) may reduce headache severity by 20% compared to 10% with monotherapy, though this requires confirmation in larger trials 8