Organization and Description of Business

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Description of Business

1. Organization and Description of Business

Description of Business

PhaseBio Pharmaceuticals, Inc. (the “Company”) was incorporated as a Delaware corporation on January 10, 2002. The Company is a clinical-stage biopharmaceutical company focused on the development and commercialization of novel therapies to treat orphan diseases, with an initial focus on cardiopulmonary indications. The Company’s lead product candidate, PB2452, is a novel reversal agent for the antiplatelet drug ticagrelor, which the Company is developing for the treatment of patients on ticagrelor who are experiencing a major bleeding event or those who require urgent surgery. The Company recently completed a Phase 1 clinical trial of PB2452 in healthy subjects and intends to initiate a Phase 2a clinical trial in healthy older subjects in the first half of 2019. The Company’s second product candidate, PB1046, is a once-weekly fusion protein currently in a Phase 2b clinical trial for the treatment of pulmonary arterial hypertension. PB1046 utilizes the Company’s proprietary half-life extending elastin-like polypeptide (“ELP”), technology, which also serves as the engine for future product pipelinecandidates.

Initial Public Offering

On October 22, 2018, the Company completed an initial public offering (“IPO”) of its common stock, which resulted in the issuance and sale of an aggregate of 9,864,666 shares of common stock at a public offering price of $5.00 per share, generating net proceeds of approximately $43.0 million after deducting underwriting discounts and commissions and other offering costs. In connection with the completion of the IPO, all then-outstanding shares of the Company’s redeemable convertible preferred stock were converted into an aggregate of 13,200,115 shares of common stock.

Upon completion of the IPO, the Company’s certificate of incorporation was amended and restated. Under the amended and restated certificate of incorporation, the Company’s authorized capital stock consists of 200,000,000 shares of common stock with a par value of $0.001 per share and 10,000,000 shares of preferred stock with a par value of $0.001 per share.

Reverse Stock Split

In October 2018, the Company effected a 11.0634-for-1 reverse split of its outstanding common stock and redeemable convertible preferred stock. No fractional shares were issued in connection with the stock split, and the par value and other terms of the common stock were not affected by the stock split. All share and per share amounts, including stock options, have been retroactively adjusted in these financial statements for all periods presented to reflect the reverse stock split. Further, exercise prices of stock options have been retroactively adjusted in these financial statements for all periods presented to reflect the reverse stock split.

Liquidity

The Company has experienced net losses and negative cash flows from operations since its inception and, as of December 31, 2018, had an accumulated deficit of $122.9million. The Company expects to continue to incur net losses for at least the next several years. As of December 31, 2018, the Company had cash and cash equivalents of $61.0 million and working capital of $58.1 million. The Company believes that its existing cash and cash equivalents are sufficient to fund its operating expenses and capital requirements into the second quarter of 2020.

Basis of Presentation

The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and the rules and regulations of the Securities and Exchange Commission (“SEC”). Any reference in these notes to applicable guidance is meantto refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) promulgated by the Financial Accounting Standards Board (“FASB”). Certain non-significant reclassifications have been made to conform the prior period presentation.

The Company manages its operations as a single reportable segment for the purposes of assessing performance and making operating decisions.