Company: SION
Filing Date: 2025-02-07
Form Type: 424B4
Source: 0001193125-25-022709
Chunk: 326

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-07
Form: 424B4
Chunk 326
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 non-lease
components together with lease components. Variable lease payments, such as periodic adjustments for inflation, reimbursement of real estate taxes, and variable common area maintenance are expensed as incurred as variable lease costs and are not
recorded on the consolidated balance sheets.

Sublease income is recognized on a straight-line basis over the term of the sublease agreement and is
recorded within Other Income on the consolidated statements of operations and comprehensive loss.

Research and Development Expenses and Accruals

Research and development costs include (i) employee-related expenses, including salaries, benefits, and stock-based compensation expense;
(ii) external research and development expenses incurred under arrangements with third parties, such as contract research organizations (“CRO”) agreements, contract development and manufacturing organizations (“CDMOs”),
consultants and scientific advisors; (iii) costs associated with preclinical and clinical activities and (iv) lab supplies, lab expenses and an allocation of rent, depreciation, and infrastructure.

The Company enters into contracts in the normal course of business with CROs, CDMOs, and other vendors to assist in research and development activities.
These contracts generally provide for termination at any time upon a certain amount of prior notice and payment of costs incurred.

The Company
recognizes research and development costs in the periods in which they are incurred. Typically, external expenses are recognized based on an evaluation of the progress to completion of specific tasks using information provided to the Company by
their service providers as of each reporting date. Advance payments for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses, which are expensed as the related goods are
delivered or the services are performed, or when it is no longer expected that the goods will be delivered, or the services rendered. Significant judgments and estimates are made in determining the accrued, or prepaid expense balances at the end of
any reporting period.

Asset Acquisitions and Acquired In-ProcessResearch and Development Expense

The Company accounts for acquisitions of assets or a group of assets that do not meet the definition of a business as asset acquisitions based on the
cost to acquire the asset or group of assets, which include certain transaction costs. In an asset acquisition, the cost to acquire is allocated to the identifiable assets acquired and liabilities assumed based on their relative fair values as of
the acquisition date. No goodwill is recorded in an asset acquisition. Assets that are acquired in an asset acquisition for use in research and development activities that have an alternative future use are capitalized as in process