1. Organization and Description of Business TCR 2 Therapeutics Inc. (the Company) is a clinical-stage immunotherapy company developing the next generation of novel T cell therapies for patients suffering from cancer. The Company was incorporated under the laws of the State of Delaware on May 29, 2015 under the name TCR 2 , Inc. In November 2016, the Company changed its name to TCR 2 Therapeutics Inc. The Companys principal operations are located in Cambridge, Massachusetts. Initial public offering In February 2019, the Company completed the initial public offering of its common stock (the IPO) pursuant to which it issued and sold 5,750,000 shares of its common stock at a price to the public of $15.00 per share. The shares began trading on The Nasdaq Global Select Market on February 14, 2019. The aggregate net proceeds received by the Company from the offering were approximately $77.1 million. Upon the closing of the IPO, all outstanding shares of redeemable convertible preferred stock converted into 17,275,299 shares of common stock. Additionally, as of the closing of the IPO, the Company is authorized to issue 150,000,000 shares of common stock and 10,000,000 shares of preferred stock. Reverse stock split On February 1, 2019, the Company effected a 1-for-6.1938 reverse stock split of its issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for each series of the Companys redeemable convertible preferred stock. Accordingly, all share and per share amounts for all periods presented in the accompanying unaudited consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this reverse stock split and adjustment of the redeemable convertible preferred stock conversion ratios. Shelf registration statement On March 6, 2020, the Company filed a shelf registration statement on Form S-3 (the Shelf), with the Securities and Exchange Commission (SEC), which covers the offering, issuance and sale of up to an aggregate of $300.0 million of the Companys common stock, preferred stock, debt securities, warrants and/or units of any combination thereof. The Company simultaneously entered into a sales agreement with Jefferies LLC, as sales agent, to provide for the issuance and sale by the Company of up to $75.0 million of its common stock from time to time in at-the-market offerings under the Shelf, which the Company refers to as the ATM Program. The Shelf was declared effective by the SEC on April 28, 2020. As of September 30, 2020, no sales have been made pursuant to the ATM Program. Equity offering On July 31, 2020, the Company closed a public offering of its common stock pursuant to which it issued and sold 9,200,000 shares of its common stock at a price to the public of $15.50 per share. The aggregate net proceeds received by the Company from the offering were approximately $133.6 million after deducting $9.0 million relating to underwriting discounts and commissions and offering expenses.