Xenon Pharmaceuticals Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-Q

(Mark One)

For the quarterly period ended June 30,2026

OR

For the transition period from__________ to__________

Commission File Number:001-36687

(Exact name of Registrant as Specified in its Charter)

Registrant’s telephone number, including area code: (604)484-3300

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes☐ No☒

As of August 3, 2026, the registrant had 96,840,432 common shares, without par value, outstanding.

QUARTERLY REPORT ON FORM 10-Q

FOR THE QUARTER ENDED JUNE 30, 2026

TABLE OF CONTENTS

In this Quarterly Report on Form 10-Q, “we,” “our,” “us,” “Xenon,” and “the Company” refer to Xenon Pharmaceuticals Inc. and its subsidiary. “Xenon” and the Xenon logo are the property of Xenon Pharmaceuticals Inc. and are registered in the United States and used or registered in various other jurisdictions. This report contains references to our trademarks and to trademarks belonging to other entities. Solely for convenience, trademarks and trade names referred to in this report may appear without the ® or ™ symbols, but such references are not intended to indicate, in any way, that their respective owners will not assert, to the fullest extent under applicable law, their rights thereto. We do not intend our use or display of other companies’ trade names or trademarks to imply a relationship with, or endorsement or sponsorship of us by, any other companies.

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Risk Factors Summary

Our business is subject to numerous risks and uncertainties, including those highlighted in the section of this report captioned “Risk Factors.” The following is a summary of the principal risks we face:

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We have incurred significant losses since our inception and anticipate that we will continue to incur significant losses for the foreseeable future.

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We will need to raise additional funding, which may not be available on acceptable terms, if at all. Failure to obtain capital when needed may force us to delay, limit or terminate our product discovery and development programs or commercialization efforts or other operations.

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Our business substantially depends upon the successful development of azetukalner. If we are unable to obtain regulatory approval for, and successfully commercialize, azetukalner, our business may be materially harmed.

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Clinical studies may fail to demonstrate adequately the safety and efficacy of our, or our collaborators’, product candidates at any stage of clinical development. Terminating the development of any of our, or our collaborators’, product candidates could materially harm our business and the market price of our common shares.

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We, or our collaborators, may find it difficult to enroll patients in our clinical studies which could delay or prevent the successful completion of clinical studies of our product candidates.

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We, or our collaborators, may incur unexpected costs or experience delays in completing, or ultimately be unable to complete, the development and commercialization of our, or our collaborators’, product candidates.

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The regulatory approval processes of the FDA, EMA and regulators in other foreign jurisdictions are lengthy, time-consuming and inherently unpredictable. If we, or our collaborators, are unable to obtain regulatory approval for our product candidates in a timely manner, or at all, our business may be substantially harmed.

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If we are unable to establish our own sales, marketing and distribution capabilities or enter into agreements for these purposes, we may not be successful in independently commercializing any future products.

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Our prospects for successful development and commercialization of our partnered products and product candidates are dependent upon the research, development and marketing efforts of our collaborators.

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Our reliance on third parties to manufacture our product candidates may increase the risk that we will not have sufficient quantities of our product candidates, raw materials, APIs or drug products when needed or at an acceptable cost.

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We rely on third parties to conduct our pre-clinical studies and clinical studies. If these third parties do not successfully carry out their contractual duties, including to comply with applicable laws and regulations or meet expected deadlines, our business could be substantially harmed.

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We could be unsuccessful in obtaining or maintaining adequate patent protection for one or more of our products, product candidates or future products.

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We may not be able to protect our intellectual property rights throughout the world.

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Our business and operations could suffer in the event of an actual or perceived information security incident such as a cybersecurity breach, system failure or other compromise of our systems and/or information, including information held by a third-party contractor or vendor.

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The market price of our common shares may be volatile, and purchasers of our common shares could incur substantial losses.

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Future sales and issuances of our common shares or securities convertible into or exchangeable for common shares would cause our shareholders to incur dilution and could cause the market price of our common shares to fall.

Our Risk Factors are not guarantees that no such conditions exist as of the date of this report and should not be interpreted as an affirmative statement that such risks or conditions have not materialized, in whole or in part.

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