Products Liability Law Daily Wrap Up, PREEMPTION—DRUGS—1st Cir.: Seizure patient’s estate may amend complaint against Amgen about Aimovig biologic labeling, (Oct 19, 2026)

By Justin Marcus Smith, J.D.

The court affirmed dismissal for “impossibility” preemption; however, amendment was not certainly futile because the estate made a presentation of newly acquired information forming a basis for a label change.

A state law complaint about the labeling of Aimovig, an Amgen Inc. biologic drug, could not withstand Amgen’s affirmative defense of “impossibility” preemption, held the U.S. Court of Appeals for the First Circuit, in affirming dismissal. That Amgen could have proposed a different original label did not defeat impossibility preemption because Amgen could not have acted unilaterally in the context of a “pre-approval” claim, the FDA ultimately made the final labeling decision. It was also clear that the FDA would have rejected the type of labeling now proposed, but Amgen chose not to rely on this argument to sustain the district court’s Fed. R. Civ. P. 15(a) futility determination. The First Circuit held instead that amendment of the complaint was not necessarily futile. The court reasoned it could not exclude the possibility that certain study findings were newly acquired information that would have allowed Amgen to unilaterally change Aimovig’s approved label to add a warning under the Changes Being Effected (CBE) procedure. The First Circuit accordingly reversed the district court’s denial of leave to amend and remanded (Warner v. Amgen Inc., No. 25-1268 (1st Cir. Oct. 9, 2026)).

Background. According to a district court complaint, a patient who suffered from seizures and cerebrovascular complications died about 18 months after taking a single dose of the Amgen drug Aimovig, a biologic for the treatment of migraines. Aimovig is a calcitonin gene-related peptide (CGRP) receptor antagonist.

The patient’s mother, acting as the personal representative of the patient’s estate, brought a state law challenge to the adequacy of the drug’s label as originally approved by the FDA. After removal from state court, the district court dismissed the complaint with prejudice as preempted by the federal Food, Drug, and Cosmetic Act (FDC Act), 21 U.S.C. §§ 301 et seq. The district court concluded amendment of the complaint would have been futile, and the estate appealed.

Amgen had submitted a biologics license application (BLA) for Aimovig in 2017, and the FDA approved it in 2018. Section 14 of the Aimovig label, titled “Clinical Studies,” stated that patients with certain circulatory conditions, including transient strokes, were excluded from the drug’s clinical trials. The estate criticized that description because it failed to disclose that the Aimovig studies excluded anyone, like the decedent, who had ever suffered from seizures or neurological disorders. The patient’s death certificate allegedly stated that “complications from Aimovig” contributed to his death.

At the hearing on Amgen’s motion to dismiss, the estate introduced a new contention that a series of studies or articles not known to the FDA at time of approval would have allowed Amgen to employ the CBE procedure to change the label after it was approved and before the patient took the drug. However, the district court ruled the articles were not newly acquired information and that they failed to link Aimovig or similar drugs to an adverse event or risk that would have allowed Amgen to affect a CBE change to the Aimovig label (see Amgen migraine medicine wrongful death suit dismissed due to preemption, Feb. 19, 2025).

On the estate’s appeal of dismissal, Amgen argued the district court correctly found that Amgen’s federal preemption affirmative defense precluded the estate’s state-law claim. Amgen’s FDC Act “impossibility” preemption defense rested on the proposition that it was legally impossible to use a label other than the label the FDA originally approved. The First Circuit applied de novo review to both the district court’s decision to dismiss and the decision to deny amendment for futility.

Pre-approval theory. The court affirmed dismissal on the impossibility preemption defense insofar as it found two flaws in the estate’s “pre-approval” theory. The first was that, as a matter of law, a drug manufacturer’s freedom to ask the FDA for a label change did not mean the manufacturer had the unilateral power of action necessary to preclude impossibility preemption. In other words, the fact that a manufacturer could ask for a change did not mean it would get one. The FDA had a say, it could reject such a request, and that did not necessarily exclude the impossibility defense.

The second flaw was the fact that the record in this case made it clear that the FDA would have rejected a request to further describe exclusions from clinical trials on the Aimovig label. In approving a final label for a new drug or biologic, the FDA aims to warn of risks while at the same time preventing overwarning that may deter appropriate use of medical products. The final label the FDA approved here listed only certain common adverse reactions. While the clinical studies section made certain disclosures, it did not disclose the lifetime exclusion criterion the estate disputed here, and it included no warning of a theoretical risk allegedly left unresolved by the design of the clinical studies conducted for the approval.

The First Circuit analyzed that the only reason to change the label would have been to flag theoretical risks the agency had already decided did not warrant mentioning. The court said it must read the FDA’s decision not to include the lifetime exclusion as a final agency determination. In that context, the agency would have rejected an Amgen suggestion to include in the approved label the language that the patient’s estate argued state law required. In light of these circumstances, the estate could not overcome Amgen’s impossibility preemption affirmative defense. Dismissal was proper.

Amendment denial. Even if dismissal was proper, that did not mean amendment was necessarily futile, and the First Circuit concluded it did not have the certitude necessary to affirm denial of leave to amend. The estate made three key showings. First, it showed there was a reasonable basis for treating the content of four of nine studies or articles the estate presented during motion practice as newly acquired information. For example, the court said it could not determine at the dismissal stage that the FDA’s world-literature review included studies on how CGRP antagonism interacts with the blood-brain barrier. Viewed together, four studies the estate presented during dismissal motion practice plausibly suggested risks of CGRP antagonism outside of its effect on regulating blood flow in the body.

Next, the court found the estate was attempting to achieve one of the five permissible objectives under the CBE procedure. The discussion here was brief because the parties did not dispute that the change the estate proposed would have strengthened a warning on the Aimovig label.

Last, the court turned to the issue of causal association and treated it as a question of law. To add an adverse reaction to a drug label, a manufacturer need only have some basis to believe there is a causal relationship between the drug and the occurrence of an adverse event. Causation does not need to be established definitely for a warning to be required. The First Circuit found the four articles the estate submitted could be read as finding an association between CGRP antagonism and the circumstances the decedent allegedly experienced. The court could not exclude the possibility of a CBE procedure change to the Aimovig label with the certainty necessary to affirm the district court decision to deny amendment on the basis of futility.

The case is No. 25-1268.

Judge: Kayatta, W.

Attorneys: John Ferris Dow (Dow Law Group, LLC) for Elissa E. Warner. Johannah Cassel-Walker (Hogan Lovells Cadwalader US LLP) for Amgen Inc. and Amgen USA Inc. Kyle E. Bjornlund (Cetrulo LLP) for Novartis Institute for Biomedical Research, Inc.

Companies: Amgen Inc.; Amgen USA Inc.; Novartis Institute for Biomedical Research, Inc.

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