CGRPs: They’ve Been a Long Time Coming

Editors’ note: For the April edition of Expert Perspectives, we asked two leading neurologists to present differing views on the use of calcitonin gene-related peptide (CGRPs) monoclonal antibodies (mAbs) for the treatment of migraine. Here, Jack D. Schim, MD, of the Neurology Center of Southern California, discusses the observed benefits of the CGRP mAbs. To read a counter-argument in which Lawrence Robbins, MD, of the Robbins Headache Clinic in Riverwoods, IL, discusses potential safety concerns associated with this drug class, click here.

Dr. Schim is Co-Director of The Headache Center of Southern California, The Neurology Center.  He is Board Member and past President of the Headache Consortium of the Pacific, Board Member and past President, American Heart Association San Diego, a Past President of the California Neurologic Society, and an active member of the American Academy of Neurology, American Stroke Association, and American Headache Society.

The identification of CGRP as a crucial pain signaling molecule in the trigeminal pathway, thereby establishing its link to migraine pain, has transformed care for patients with episodic and chronic migraine. Since 2018, the FDA has approved 4 monoclonal antibodies (mAbs) that either block the CGRP receptor or bind its ligand to prevent attachment to the receptor. 

These medications are helping patients with medication overuse headache (MOH) and chronic migraine; one study involving 139 patients showed that half the patients saw their headache days per month cut by half, and migraine days per month cut by 62%. In another small study, 23 patients (47%) with medication overuse headache reported having no MOH issues after 3 months. Most of these patients had a history of medication overuse, but no specific diagnosis of MOH.

In a survey, 277 physicians said that nearly half of their patients had resistant migraine, and 29% had refractory migraine. For these patients, the mAbs have helped restore some normalcy in their lives.  

But are these medications safe? Some clinicians posed this question even before the 2018 approval.

It is a valid question. The CGRP neuropeptide is a powerful dilator, establishing vascular homeostasis, organ development in utero, wound healing, and more. It is expressed in the peripheral and central nervous system and found abundantly in neurons and the unmyelinated A-fibers of the peripheral trigeminovascular system and trigeminal ganglion.

So, would blocking CGRP function in one area affect its function in another? So far, I have to say the answer is no. Neither the literature nor my observations say otherwise. 

Trials vs the real world

Finding an answer to this question takes more than reading clinical trials data. Participants in these trials do not necessarily represent the real world – no complicated morbidities, no pregnant or lactating women. And trial lengths are generally short.

Thus, it is important to assess the safety of these medications in the real world.  

In the trials of the subcutaneous mAbs, local injection site reactions were the most common adverse event. More specifically, erenumab showed increased incidence of constipation, and  post-marketing surveillance has revealed some risk of hypertension; pooled analysis from 4 trial phases showed that across treatment groups, 20 people out of 2443 began treatment for hypertension. Some patients enrolled in trials for atogepant, an oral small molecule CGRP receptor agonist, also reported constipation and nausea, suggesting that receptor blockade may result in a higher incidence of GI disturbance. In addition, these medicines on occasion have caused alopecia, fatigue, or achiness. 

Eptinezumab is administered intravenously, every 3 months, and thus does not have injection site reactions as a safety concern. In clinical trials, the most common adverse event was nasopharyngitis and hypersensitivity; Datta et al have provided a summary of safety and efficacy.

Raynaud’s and cluster headaches

A retrospective chart review study from the Mayo Clinic looking at individuals with Raynaud’s disease who were treated with CGRP antagonists showed that 5.3% of 169 patients had microvascular complications such as gangrene or autoimmune necrosis. There was no significant difference in demographic characteristics or rheumatologic history among those with Raynaud's who did or did not experience complications. In addition, microvascular complications of migraine therapies have preceded the use of CGRP modulators, as this has been documented in the past with other vasoactive substances such as ergots, triptans, and beta blockers. 

In a tolerability and safety study of galcanezumab in patients with chronic cluster headache, with up to 15 months of treatment, the most common treatment emergent adverse events were nasopharyngitis and injection site pain. In this population with 11% to 12% of individuals having baseline hypertension and nearly 63% currently using tobacco, less than 2.5% had any abnormalities on ECG.  

Vascular complications including pulmonary embolism, TIA, myocardial infarction, and atrial fibrillation have been reported but with no apparent relation between galcanezumab dosing and onset, with onset following the second to up to the eleventh monthly dose. 

Antidrug antibodies can also occur as a complication of exposure to therapeutic antibodies of this class and have been detected in up to 12% of individuals treated. This might lead to therapeutic failure but would not likely be a safety issue.

Anaphylaxis or serious hypersensitivity reactions are uncommon, and in general are the only contraindication to the use of these agents. 

Pregnancy registry information is just starting to become available. The number of reports on adverse drug reactions remains limited, and thus it is wise to avoid pregnancy and breastfeeding exposures as best as possible.

FAERS

The FDA adverse event reporting system (FAERS) database does contain reports on adverse events of approved medications. However, even the FDA website warns that the information provided regarding individual cases is unverified and wouldn’t establish causation, considering the confounding variables involved, and this information can be duplicated as well as incomplete. In addition, rates of occurrence cannot be established with reports, as the denominator of exposure is uncertain.  

With those caveats established, the most common reports in FAERS concern injection site reactions, more frequent migraine or headache, or drug ineffectiveness. While constipation has been the second most common AE for erenumab, it did not make the top 10 for fremanezumab or galcanezumab, and cardiovascular events have not ranked in the top 10 for any product. Reasons for discontinuing treatment included withdrawal by the patient (147 of 1,890 [8%]) and lack of efficacy (77 of 1,890 [4%]). 

As the reader can ascertain, different studies point out different reasons for discontinuing CGRP therapies. Other studies note that the most frequent reasons for discontinuation are lack of efficacy, constipation, and lack of insurance .

Conclusions

These medications have been well received; I believe. Fremanezumab, manufactured by Teva Pharmaceuticals, was approved in September 2018. According to Teva’s 2021 annual report, Ajovy, fremanezumab’s brand name, reached 21% market share in the US and 21% in Europe.

Aimovig, or erenumab, has been prescribed 620,000 times since its approval, according to the Novartis 2021 annual report. Galcanezumab, or Emgality, was approved in 2019, and had 65,300 prescriptions written in the since then. . Adherence to treatment has generally been very high in clinical practice, with the most common reason for a patient to switch being lack of effectiveness, rather than adverse events.

Of note, adverse events of other migraine therapeutics are not insignificant, and considering the pain that people with migraine endure, side effects must be hard to contend with for individuals to stop taking them. Case in point: A year before erenumab was approved, a study was published that looked at medical records for medication persistence in 8,700 chronic migraine patients, who all had been prescribed beta blockers, anti-seizure medications, or antidepressants. By 6 months, only 1 out of 4 patients were still taking the prescribed medicines. By 12 months, that  was down to 14%. And about one-third of patients who stopped treatment stayed untreated for at least a year. 

The presumed reasons these patients stopped their medications: side effects and-or lack of efficacy. 

Migraine is a disabling disorder, for which the mAb class of medications has been highly beneficial for large numbers of patients, with far greater tolerability than prior oral preventives. While no treatments have absolute safety, the overall safety of this class of medications has been very high, leading to much improved clinical outcomes.

Editors’ note: For the April edition of Expert Perspectives, we asked two leading neurologists to present differing views on the use of calcitonin gene-related peptide (CGRPs) monoclonal antibodies (mAbs) for the treatment of migraine. Here, Jack D. Schim, MD, of the Neurology Center of Southern California, discusses the observed benefits of the CGRP mAbs. To read a counter-argument in which Lawrence Robbins, MD, of the Robbins Headache Clinic in Riverwoods, IL, discusses potential safety concerns associated with this drug class, click here.

Dr. Schim is Co-Director of The Headache Center of Southern California, The Neurology Center.  He is Board Member and past President of the Headache Consortium of the Pacific, Board Member and past President, American Heart Association San Diego, a Past President of the California Neurologic Society, and an active member of the American Academy of Neurology, American Stroke Association, and American Headache Society.

The identification of CGRP as a crucial pain signaling molecule in the trigeminal pathway, thereby establishing its link to migraine pain, has transformed care for patients with episodic and chronic migraine. Since 2018, the FDA has approved 4 monoclonal antibodies (mAbs) that either block the CGRP receptor or bind its ligand to prevent attachment to the receptor. 

These medications are helping patients with medication overuse headache (MOH) and chronic migraine; one study involving 139 patients showed that half the patients saw their headache days per month cut by half, and migraine days per month cut by 62%. In another small study, 23 patients (47%) with medication overuse headache reported having no MOH issues after 3 months. Most of these patients had a history of medication overuse, but no specific diagnosis of MOH.

In a survey, 277 physicians said that nearly half of their patients had resistant migraine, and 29% had refractory migraine. For these patients, the mAbs have helped restore some normalcy in their lives.  

But are these medications safe? Some clinicians posed this question even before the 2018 approval.

It is a valid question. The CGRP neuropeptide is a powerful dilator, establishing vascular homeostasis, organ development in utero, wound healing, and more. It is expressed in the peripheral and central nervous system and found abundantly in neurons and the unmyelinated A-fibers of the peripheral trigeminovascular system and trigeminal ganglion.

So, would blocking CGRP function in one area affect its function in another? So far, I have to say the answer is no. Neither the literature nor my observations say otherwise. 

Trials vs the real world

Finding an answer to this question takes more than reading clinical trials data. Participants in these trials do not necessarily represent the real world – no complicated morbidities, no pregnant or lactating women. And trial lengths are generally short.

Thus, it is important to assess the safety of these medications in the real world.  

In the trials of the subcutaneous mAbs, local injection site reactions were the most common adverse event. More specifically, erenumab showed increased incidence of constipation, and  post-marketing surveillance has revealed some risk of hypertension; pooled analysis from 4 trial phases showed that across treatment groups, 20 people out of 2443 began treatment for hypertension. Some patients enrolled in trials for atogepant, an oral small molecule CGRP receptor agonist, also reported constipation and nausea, suggesting that receptor blockade may result in a higher incidence of GI disturbance. In addition, these medicines on occasion have caused alopecia, fatigue, or achiness. 

Eptinezumab is administered intravenously, every 3 months, and thus does not have injection site reactions as a safety concern. In clinical trials, the most common adverse event was nasopharyngitis and hypersensitivity; Datta et al have provided a summary of safety and efficacy.

Raynaud’s and cluster headaches

A retrospective chart review study from the Mayo Clinic looking at individuals with Raynaud’s disease who were treated with CGRP antagonists showed that 5.3% of 169 patients had microvascular complications such as gangrene or autoimmune necrosis. There was no significant difference in demographic characteristics or rheumatologic history among those with Raynaud's who did or did not experience complications. In addition, microvascular complications of migraine therapies have preceded the use of CGRP modulators, as this has been documented in the past with other vasoactive substances such as ergots, triptans, and beta blockers. 

In a tolerability and safety study of galcanezumab in patients with chronic cluster headache, with up to 15 months of treatment, the most common treatment emergent adverse events were nasopharyngitis and injection site pain. In this population with 11% to 12% of individuals having baseline hypertension and nearly 63% currently using tobacco, less than 2.5% had any abnormalities on ECG.  

Vascular complications including pulmonary embolism, TIA, myocardial infarction, and atrial fibrillation have been reported but with no apparent relation between galcanezumab dosing and onset, with onset following the second to up to the eleventh monthly dose. 

Antidrug antibodies can also occur as a complication of exposure to therapeutic antibodies of this class and have been detected in up to 12% of individuals treated. This might lead to therapeutic failure but would not likely be a safety issue.

Anaphylaxis or serious hypersensitivity reactions are uncommon, and in general are the only contraindication to the use of these agents. 

Pregnancy registry information is just starting to become available. The number of reports on adverse drug reactions remains limited, and thus it is wise to avoid pregnancy and breastfeeding exposures as best as possible.

FAERS

The FDA adverse event reporting system (FAERS) database does contain reports on adverse events of approved medications. However, even the FDA website warns that the information provided regarding individual cases is unverified and wouldn’t establish causation, considering the confounding variables involved, and this information can be duplicated as well as incomplete. In addition, rates of occurrence cannot be established with reports, as the denominator of exposure is uncertain.  

With those caveats established, the most common reports in FAERS concern injection site reactions, more frequent migraine or headache, or drug ineffectiveness. While constipation has been the second most common AE for erenumab, it did not make the top 10 for fremanezumab or galcanezumab, and cardiovascular events have not ranked in the top 10 for any product. Reasons for discontinuing treatment included withdrawal by the patient (147 of 1,890 [8%]) and lack of efficacy (77 of 1,890 [4%]). 

As the reader can ascertain, different studies point out different reasons for discontinuing CGRP therapies. Other studies note that the most frequent reasons for discontinuation are lack of efficacy, constipation, and lack of insurance .

Conclusions

These medications have been well received; I believe. Fremanezumab, manufactured by Teva Pharmaceuticals, was approved in September 2018. According to Teva’s 2021 annual report, Ajovy, fremanezumab’s brand name, reached 21% market share in the US and 21% in Europe.

Aimovig, or erenumab, has been prescribed 620,000 times since its approval, according to the Novartis 2021 annual report. Galcanezumab, or Emgality, was approved in 2019, and had 65,300 prescriptions written in the since then. . Adherence to treatment has generally been very high in clinical practice, with the most common reason for a patient to switch being lack of effectiveness, rather than adverse events.

Of note, adverse events of other migraine therapeutics are not insignificant, and considering the pain that people with migraine endure, side effects must be hard to contend with for individuals to stop taking them. Case in point: A year before erenumab was approved, a study was published that looked at medical records for medication persistence in 8,700 chronic migraine patients, who all had been prescribed beta blockers, anti-seizure medications, or antidepressants. By 6 months, only 1 out of 4 patients were still taking the prescribed medicines. By 12 months, that  was down to 14%. And about one-third of patients who stopped treatment stayed untreated for at least a year. 

The presumed reasons these patients stopped their medications: side effects and-or lack of efficacy. 

Migraine is a disabling disorder, for which the mAb class of medications has been highly beneficial for large numbers of patients, with far greater tolerability than prior oral preventives. While no treatments have absolute safety, the overall safety of this class of medications has been very high, leading to much improved clinical outcomes.

Editors’ note: For the April edition of Expert Perspectives, we asked two leading neurologists to present differing views on the use of calcitonin gene-related peptide (CGRPs) monoclonal antibodies (mAbs) for the treatment of migraine. Here, Jack D. Schim, MD, of the Neurology Center of Southern California, discusses the observed benefits of the CGRP mAbs. To read a counter-argument in which Lawrence Robbins, MD, of the Robbins Headache Clinic in Riverwoods, IL, discusses potential safety concerns associated with this drug class, click here.

Dr. Schim is Co-Director of The Headache Center of Southern California, The Neurology Center.  He is Board Member and past President of the Headache Consortium of the Pacific, Board Member and past President, American Heart Association San Diego, a Past President of the California Neurologic Society, and an active member of the American Academy of Neurology, American Stroke Association, and American Headache Society.

The identification of CGRP as a crucial pain signaling molecule in the trigeminal pathway, thereby establishing its link to migraine pain, has transformed care for patients with episodic and chronic migraine. Since 2018, the FDA has approved 4 monoclonal antibodies (mAbs) that either block the CGRP receptor or bind its ligand to prevent attachment to the receptor. 

These medications are helping patients with medication overuse headache (MOH) and chronic migraine; one study involving 139 patients showed that half the patients saw their headache days per month cut by half, and migraine days per month cut by 62%. In another small study, 23 patients (47%) with medication overuse headache reported having no MOH issues after 3 months. Most of these patients had a history of medication overuse, but no specific diagnosis of MOH.

In a survey, 277 physicians said that nearly half of their patients had resistant migraine, and 29% had refractory migraine. For these patients, the mAbs have helped restore some normalcy in their lives.  

But are these medications safe? Some clinicians posed this question even before the 2018 approval.

It is a valid question. The CGRP neuropeptide is a powerful dilator, establishing vascular homeostasis, organ development in utero, wound healing, and more. It is expressed in the peripheral and central nervous system and found abundantly in neurons and the unmyelinated A-fibers of the peripheral trigeminovascular system and trigeminal ganglion.

So, would blocking CGRP function in one area affect its function in another? So far, I have to say the answer is no. Neither the literature nor my observations say otherwise. 

Trials vs the real world

Finding an answer to this question takes more than reading clinical trials data. Participants in these trials do not necessarily represent the real world – no complicated morbidities, no pregnant or lactating women. And trial lengths are generally short.

Thus, it is important to assess the safety of these medications in the real world.  

In the trials of the subcutaneous mAbs, local injection site reactions were the most common adverse event. More specifically, erenumab showed increased incidence of constipation, and  post-marketing surveillance has revealed some risk of hypertension; pooled analysis from 4 trial phases showed that across treatment groups, 20 people out of 2443 began treatment for hypertension. Some patients enrolled in trials for atogepant, an oral small molecule CGRP receptor agonist, also reported constipation and nausea, suggesting that receptor blockade may result in a higher incidence of GI disturbance. In addition, these medicines on occasion have caused alopecia, fatigue, or achiness. 

Eptinezumab is administered intravenously, every 3 months, and thus does not have injection site reactions as a safety concern. In clinical trials, the most common adverse event was nasopharyngitis and hypersensitivity; Datta et al have provided a summary of safety and efficacy.

Raynaud’s and cluster headaches

A retrospective chart review study from the Mayo Clinic looking at individuals with Raynaud’s disease who were treated with CGRP antagonists showed that 5.3% of 169 patients had microvascular complications such as gangrene or autoimmune necrosis. There was no significant difference in demographic characteristics or rheumatologic history among those with Raynaud's who did or did not experience complications. In addition, microvascular complications of migraine therapies have preceded the use of CGRP modulators, as this has been documented in the past with other vasoactive substances such as ergots, triptans, and beta blockers. 

In a tolerability and safety study of galcanezumab in patients with chronic cluster headache, with up to 15 months of treatment, the most common treatment emergent adverse events were nasopharyngitis and injection site pain. In this population with 11% to 12% of individuals having baseline hypertension and nearly 63% currently using tobacco, less than 2.5% had any abnormalities on ECG.  

Vascular complications including pulmonary embolism, TIA, myocardial infarction, and atrial fibrillation have been reported but with no apparent relation between galcanezumab dosing and onset, with onset following the second to up to the eleventh monthly dose. 

Antidrug antibodies can also occur as a complication of exposure to therapeutic antibodies of this class and have been detected in up to 12% of individuals treated. This might lead to therapeutic failure but would not likely be a safety issue.

Anaphylaxis or serious hypersensitivity reactions are uncommon, and in general are the only contraindication to the use of these agents. 

Pregnancy registry information is just starting to become available. The number of reports on adverse drug reactions remains limited, and thus it is wise to avoid pregnancy and breastfeeding exposures as best as possible.

FAERS

The FDA adverse event reporting system (FAERS) database does contain reports on adverse events of approved medications. However, even the FDA website warns that the information provided regarding individual cases is unverified and wouldn’t establish causation, considering the confounding variables involved, and this information can be duplicated as well as incomplete. In addition, rates of occurrence cannot be established with reports, as the denominator of exposure is uncertain.  

With those caveats established, the most common reports in FAERS concern injection site reactions, more frequent migraine or headache, or drug ineffectiveness. While constipation has been the second most common AE for erenumab, it did not make the top 10 for fremanezumab or galcanezumab, and cardiovascular events have not ranked in the top 10 for any product. Reasons for discontinuing treatment included withdrawal by the patient (147 of 1,890 [8%]) and lack of efficacy (77 of 1,890 [4%]). 

As the reader can ascertain, different studies point out different reasons for discontinuing CGRP therapies. Other studies note that the most frequent reasons for discontinuation are lack of efficacy, constipation, and lack of insurance .

Conclusions

These medications have been well received; I believe. Fremanezumab, manufactured by Teva Pharmaceuticals, was approved in September 2018. According to Teva’s 2021 annual report, Ajovy, fremanezumab’s brand name, reached 21% market share in the US and 21% in Europe.

Aimovig, or erenumab, has been prescribed 620,000 times since its approval, according to the Novartis 2021 annual report. Galcanezumab, or Emgality, was approved in 2019, and had 65,300 prescriptions written in the since then. . Adherence to treatment has generally been very high in clinical practice, with the most common reason for a patient to switch being lack of effectiveness, rather than adverse events.

Of note, adverse events of other migraine therapeutics are not insignificant, and considering the pain that people with migraine endure, side effects must be hard to contend with for individuals to stop taking them. Case in point: A year before erenumab was approved, a study was published that looked at medical records for medication persistence in 8,700 chronic migraine patients, who all had been prescribed beta blockers, anti-seizure medications, or antidepressants. By 6 months, only 1 out of 4 patients were still taking the prescribed medicines. By 12 months, that  was down to 14%. And about one-third of patients who stopped treatment stayed untreated for at least a year. 

The presumed reasons these patients stopped their medications: side effects and-or lack of efficacy. 

Migraine is a disabling disorder, for which the mAb class of medications has been highly beneficial for large numbers of patients, with far greater tolerability than prior oral preventives. While no treatments have absolute safety, the overall safety of this class of medications has been very high, leading to much improved clinical outcomes.