Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2024
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations Poseida Therapeutics, Inc. (the “Company” or “Poseida”) is a clinical-stage cell therapy and genetic medicines company advancing a new class of treatments for patients with cancer and rare diseases. The Company has discovered and is developing a broad portfolio of product candidates in a variety of indications based on its core proprietary platforms, including its non-viral piggyBac DNA Delivery System, Cas-CLOVER Site-specific Gene Editing System and nanoparticle-based gene delivery technologies. The Company is subject to risks and uncertainties common to development-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with government regulations and the ability to secure additional capital to fund operations. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s therapeutic development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales.
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying condensed consolidated financial statements reflect the Company’s financial position, results of operations and cash flows, in conformity with generally accepted accounting principles in the United States of America (“GAAP”), for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. The accompanying condensed consolidated financial statements include the accounts of Poseida Therapeutics, Inc. and its wholly owned subsidiary. All intercompany transactions and balances have been eliminated. These unaudited condensed consolidated financial statements reflect all adjustments that are, in the opinion of management, necessary to fairly state the financial position and the results of its operations and cash flows for interim periods presented. Interim-period results are not necessarily indicative of results of operations or cash flows for a full year or any subsequent interim period. The accompanying condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023, as filed with the Securities and Exchange Commission (“SEC”) on March 7, 2024 from which the Company derived its condensed consolidated balance sheet as of December 31, 2023. We have reclassified certain amounts previously reported in our financial statements to conform to the current presentation.
Risk and Uncertainties	Risk and Uncertainties Global events such as the conflict in the Middle East, Russia’s invasion of Ukraine and the retaliatory measures that have been taken, or could be taken in the future, by the United States, NATO, and other countries have created global security concerns that could result in a regional conflict and otherwise have a lasting impact on regional and global economies, any or all of which could disrupt the Company’s supply chain and adversely affect its ability to conduct ongoing and future clinical trials of the Company’s product candidates. The extent to which any such ongoing or future conflict ultimately impacts the Company’s business is highly uncertain and cannot be predicted with confidence at this time.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. On an ongoing basis, the Company evaluates its estimates, which include, but are not limited to, estimates related to revenue, accrued expenses, research and development expenses, stock-based compensation expense and deferred tax valuation allowances. The Company bases its estimates on historical experience and other market-specific or relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions.
Cash, Cash Equivalents and Short-term Investments	Cash, Cash Equivalents and Short-term Investments The Company considers all highly liquid investments purchased with original final maturities of 90 days or less from the date of purchase to be cash equivalents. Cash and cash equivalents consist of deposits with financial institutions and marketable securities. Investments with a remaining maturity when purchased of greater than three months are classified as short-term investments in the consolidated balance sheet and consist primarily of U.S. Treasury and other government agency obligations. As the Company’s entire investment portfolio is considered available for use in current operations, the Company classifies all investments as available-for-sale and as current assets, even though the stated maturity date may be one year or more beyond the current consolidated balance sheet date, which reflects management’s intention to use the proceeds from sales of these securities to fund its operations, as necessary.
Concentration of Business Risk	Concentration of Business Risk The Company operates in one reportable business segment and has two customers. The Company relies, and expects to continue to rely, on a small number of vendors to manufacture supplies and materials for its development programs. These programs could be adversely affected by a significant interruption in these manufacturing services.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments, which potentially subject the Company to a significant concentration of credit risk, consist primarily of cash and cash equivalents and short-term investments. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits and investments are held. The Company invests exclusively in securities issued by the U.S. government or U.S. government agencies, or in money-market funds. The Company maintains an investment policy with investment objectives to preserve principal, achieve liquidity requirements, and safeguard funds. For these reasons, management believes that the Company is not exposed to significant credit risk.
Revenue Recognition	Revenue Recognition The Company’s revenues to date have been generated primarily through collaboration and license agreements. The Company’s collaboration and license agreements may contain multiple elements including intellectual property licenses and research, and development services. Consideration the Company receives under these arrangements may include upfront payments, research and development funding, cost reimbursements, research, development, regulatory and commercial milestone payments, and royalty payments. The Company applies Accounting Standard Codification Topic 606, Revenue from Contracts with Customers (“ASC 606”), issued by the Financial Accounting Standards Board (“FASB”) to account for its contracts with customers. Under ASC 606, revenue is recognized when a customer obtains control of promised goods or services. The amount of revenue recognized reflects the consideration that the Company expects to be entitled to receive in exchange for these services. The Company analyzes the nature of these performance obligations in the context of individual collaboration and license agreements in order to assess the distinct performance obligations. The Company evaluates its contracts with customers for proper classification in the consolidated statements of operations and comprehensive loss based on the nature of the underlying activity. Transactions with customers recorded in the Company’s consolidated statements of operations and comprehensive loss are recorded on either a gross or net basis, depending on the characteristics of the collaborative relationship. To determine revenue recognition for arrangements within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price, including variable consideration, if any; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that it will collect the consideration to which it is entitled in exchange for the goods or services it transfers to the customer. The Company allocates the transaction price to individual performance obligations on their relative standalone selling price basis. Standalone selling prices are based on observable prices at which the Company separately sells the products or services. If a standalone selling price is not directly observable, then the Company estimates the standalone selling price considering market conditions and entity-specific factors including, but not limited to, features and functionality of the products and services. For each agreement entered into, including licenses granted upon the exercise of license options, the Company determines the contract term for purposes of applying the requirements of ASC 606. Generally, the Company’s agreements are terminable at the option of the licensee with advance notice. The Company evaluates these termination rights to determine the contract term and whether a substantive termination penalty would be incurred by the licensee upon termination. If the licensee incurs a substantive termination penalty upon termination, the contract term for revenue recognition purposes is generally equal to the stated term of the agreement, which many times is equal to the research term. Alternatively, if the licensee does not incur a substantive termination penalty upon termination, the contract term for revenue recognition purposes may be shorter than the stated term of the agreement, in which case the termination rights may be accounted for as contract renewal options. The determination of whether a substantive termination penalty is associated with the termination rights requires significant judgment. In making this determination, the Company considers, among other things, the nature of the rights that would be returned to the Company upon termination, exclusivity rights, stage of development of the licensed products, payment terms, including the amount and timing of non-refundable or guaranteed payments, and the business purpose of the termination rights granted. If the customer options are determined to represent a material right, the material right is recognized as a separate performance obligation at the outset of the arrangement. The Company allocates the transaction price to material rights based on the standalone selling price. As a practical alternative to estimating the standalone selling price when the goods or services are both (i) similar to the original goods and services in the contract and (ii) provided in accordance with the terms of the original contract, the Company allocates the total amount of consideration expected to be received from the customer to the total goods or services expected to be provided to the customer. The Company receives payments from its collaborators based on terms established in each contract. Upfront payments and other payments may require deferral of revenue recognition to a future period until the Company satisfies its performance obligations under the contract.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources, including unrealized gains and losses on short-term investments. Comprehensive gains (losses) have been reflected in the unaudited condensed consolidated statements of operations and comprehensive loss for all periods presented.
Emerging Growth Company Status	Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these condensed consolidated financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.

Poseida Therapeutics, Inc. 10-Q