Description of Business	3 Months Ended
Description of Business	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business Alpine Immune Sciences, Inc. (the “Company”, “Alpine”, “we”, “us”, or “our”), together with its consolidated subsidiaries, is a clinical-stage biopharmaceutical company dedicated to discovering and developing innovative, protein-based immunotherapies to treat autoimmune and inflammatory diseases. Our approach includes a proprietary scientific platform that converts native immune system proteins into differentiated, multi-targeted therapeutics. We are seeking to create first- or best-in-class multifunctional immunotherapies via our unique protein engineering technologies to improve outcomes in patients with serious diseases. We were incorporated under the laws of the State of Delaware and are headquartered in Seattle, Washington. Merger Agreement In April 2024, we entered into an agreement and plan of merger (the “Merger Agreement”) with Vertex Pharmaceuticals Incorporated (“Vertex”) and their wholly owned subsidiary, Adams Merger Sub, Inc. (“Purchaser”). On April 22, 2024, Purchaser commenced a cash tender offer (the “Offer”) to acquire all of our issued and outstanding shares of common stock (the “Shares”) for $65.00 per share in cash (the “Offer Price”). Following consummation of the Offer and subject to the satisfaction or waiver of certain conditions, Purchaser will merge with and into Alpine, upon the terms and subject to the conditions set forth in the Merger Agreement, with Alpine surviving as a wholly owned subsidiary of Vertex (the “Merger”). As a result of the Merger, Alpine will cease to be a publicly traded company. The transaction is expected to close in the second quarter of 2024, subject to certain closing conditions, including the tender of the majority of our outstanding shares of common stock, the expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act, and other customary closing conditions. The Offer is described in a Tender Offer Statement on Schedule TO (as may be amended or supplemented from time to time, the “Schedule TO”), which was filed by Purchaser and Vertex with the Securities and Exchange Commission (the “SEC”) on April 22, 2024.

ALPINE IMMUNE SCIENCES, INC. 10-Q