Xenon Pharmaceuticals Inc. and Neurocrine Biosciences, Inc. announced that on January 13, 2021, entered into an amendment to the License and Collaboration Agreement originally entered into on December 2, 2019 pursuant to which the parties revised certain investigational new drug application acceptance criteria relating to Neurocrine's NBI-921352 product candidate for the potential treatment of SCN8A-DEE. Under the terms of the Amendment, a partial IND acceptance for the Product Candidate in the SCN8A-DEE indication will be deemed to have occurred upon the authorization of the U.S. Food and Drug Administration to initiate a Phase 2 randomized, double-blind, placebo-controlled study to evaluate the efficacy, safety, tolerability, and pharmacokinetics of the Product Candidate in subjects with SCN8A-DEE aged between 12 and 21 years. A full IND acceptance for the Product Candidate in the SCN8A-DEE indication will be deemed to have occurred upon FDA approval of a protocol amendment to the Study that expands the subject population to include subjects with SCN8A-DEE aged between 2 years and 11 years.

If the Product Candidate achieves Full IND Acceptance in SCN8A-DEE or IND or equivalent regulatory authority acceptance in a Major Indication (each of Full IND Acceptance for SCN8A-DEE or IND or equivalent regulatory acceptance in a Major Indication are referred to as an “IND Acceptance”), the Company will be entitled to a milestone cash payment of $11.25 million or $4.5 million, respectively. In addition to such cash payment, the Company will issue and sell either $13.75 million or $5.5 million of its common shares to Neurocrine, depending on whether the IND Acceptance is for SCN8A-DEE or a Major Indication, respectively (the “Milestone Equity Purchase”). The common shares sold to Neurocrine in the Milestone Equity Purchase will have a price equal to 115% of the Company's 30-day volume-weighted average price immediately prior to the public announcement of the IND Acceptance.

'Major Indication' means an indication that meets or exceeds a specified prevalence threshold, including without limitation, focal seizures. If the IND Acceptance first occurs for a Major Indication and subsequently Full IND Acceptance for the Product Candidate in SCN8A-DEE occurs, Neurocrine will pay to the Company an additional $6.75 million cash payment and an additional $8.25 million of common shares will be issued and sold to Neurocrine at a price equal to 115% of the Company's 30-day volume-weighted average price immediately prior to the public announcement of the subsequent IND Acceptance. If the aggregate number of common shares to be sold to Neurocrine pursuant to the terms of the Collaboration Agreement, as amended by the Amendment, would exceed 19.9% of the Company's common shares outstanding on the date of the Collaboration Agreement, then the number of shares to be purchased shall be reduced such that the percentage cap is not exceeded.