and the exploration of its potential utility in other indications, populations and formulations. We will continue to invest in our GI-focused product candidates as we advance them through pre-clinical and clinical trials, in addition to funding research and development activities under our external collaboration and license agreements.
Acquired In-Process Research and Development
Asset acquisition costs, license fees and development milestone payments related to acquired and in-licensed products and technology are expensed as acquired in-process research and development at the point that they have no established alternative future use.
Through the VectivBio Acquisition, we are advancing apraglutide, a next-generation, long-acting synthetic peptide analog of GLP-2, as a differentiated therapeutic for a wide range of rare diseases, including SBS-IF and acute Graft versus Host Disease, or aGvHD.
Apraglutide for SBS-IF. We are conducting a Phase III clinical trial, STARS, to assess the safety and efficacy of apraglutide in adult patients with SBS-IF, and expect to report topline results in March 2024. In addition to the STARS trial, we are conducting the STARS Nutrition and Open Label Extension studies to evaluate the efficacy, safety and tolerability of apraglutide in SBS-IF further and to support potential submissions of marketing applications for apraglutide in the United States, European Union, and Japan. In October 2023, we presented positive final data from the STARS Nutrition Phase II study of apraglutide in patients with SBS-IF and colon-in-continuity.
Apraglutide for aGvHD: We are conducting a Phase II proof-of-concept clinical trial, STARGAZE, to evaluate apraglutide in patients with steroid-refractory gastrointestinal aGvHD and expect data in the first quarter of 2024.
CoMET Platform: We, through the VectivBio Acquisition, also added the CoMET Platform, a small molecule platform technology that exploits the central role of Co-enzyme A, in intermediary metabolism and the significant dysregulation of this essential cofactor across multiple disorders. Ironwood is in the process of evaluating this asset and will provide additional details on plans in the future.
Selling, General and Administrative Expense. Selling, general and administrative expense consists primarily of compensation, benefits and other employee-related expenses for personnel in our administrative, finance, legal, information technology, business development, commercial, sales, marketing, communications and human resource functions. Other costs include legal costs of pursuing patent protection of our intellectual property, general and administrative related facility costs, insurance costs and professional fees for accounting, tax, consulting, legal and other services. As we continue to invest in the commercialization of LINZESS, we expect our selling, general and administrative expenses will be substantial for the foreseeable future.
We include AbbVie’s selling, general and administrative cost-sharing payments in the calculation of the net profits and net losses from the sale of LINZESS in the U.S. and present the net payment to or from AbbVie as collaboration expense or collaborative arrangements revenue, respectively.
Restructuring Expenses. Restructuring expenses pertain to a workforce reduction in April 2023 and restructuring initiatives commencing in June 2023 in connection with the VectivBio Acquisition. The workforce reduction and restructuring initiatives are more fully described in Note 13, Workforce Reductions and Restructuring.
Interest Expense and Other Financing Costs. Interest expense consists primarily of cash and non-cash interest costs related to our convertible senior notes and Revolving Credit Facility. Non-cash interest expense consists of amortization of debt issuance costs.
Interest and Investment Income. Interest and investment income consists of interest earned on our cash and cash equivalents, as well as significant financing components of payments due from collaboration partners.
Gain on Derivatives. In June 2015, we issued 2.25% Convertible Senior Notes due June 15, 2022, or the 2022 Convertible Notes, and in August 2019, we issued 0.75% Convertible Senior Notes due 2024, or the 2024 Convertible Notes, and 1.50% Convertible Senior Notes due 2026, or the 2026 Convertible Notes (together with the 2024 Convertible Notes, the Convertible Senior Notes). In connection with the issuance of our 2022 Convertible Notes, we entered into convertible note hedge transactions, or the Convertible Note Hedges, and separate note hedge warrant transactions, or the Note Hedge Warrants, with certain financial institutions. Gain on derivatives consists of the change