Precision to Provide PBCAR0191 Update via Hosted Conference Call and Webcast on Friday, June 4, 2021

Precision BioSciences, Inc. (Nasdaq: DTIL), a clinical stage biotechnology company developing allogeneic CAR T and in vivo gene correction therapies, today announced that additional data from its Phase 1/2a study of PBCAR0191, the Company’s first generation, off-the-shelf allogeneic CAR T candidate targeting CD19 will be presented at the 2021 American Society of Clinical Oncology (ASCO) Meeting being held virtually June 4-8, 2021.

Abstracts are available and can be viewed on the ASCO web site at www.asco.org. Additional data including updated response rates, safety, and durability will be presented at the ASCO meeting.

Title: Preliminary safety and efficacy of PBCAR0191, an allogeneic, off-the-shelf CD19-targeting CAR T product, in relapsed/refractory (r/r) CD19+ NHL

Poster Session: Hematologic Malignancies—Lymphoma and Chronic Lymphocytic Leukemia, Abstract 7516

Date/Time: Friday, June 4, 2021 at 9:00 a.m. ET

Presenting Author: Bijal Shah, M.D., Moffitt Cancer Center

By February 1, 2021, 13 patients with R/R non-Hodgkin lymphoma (NHL) met study eligibility criteria and had received PBCAR0191 dose level 3 at 3x10⁶ or equivalent with either standard lymphodepletion (sLD) (n=6)¹ or enhanced lymphodepletion (eLD) (n=7)². Of these patients, 77% had aggressive lymphomas and 62% had four or more courses of prior treatment. PBCAR0191 continued to demonstrate an acceptable safety profile with no cases of graft versus host disease, no cases of Grade ≥ 3 cytokine release syndrome, and no cases of Grade ≥ 3 immune effector cell-associated neurotoxicity syndrome.

“These results continue to confirm the activity of PBCAR0191 with strategies that mitigate rejection, and we look forward to sharing additional data in the poster and on our hosted conference call on June 4,” said Alan List, M.D., Chief Medical Officer at Precision BioSciences. “While we continue to advance PBCAR0191 through its Phase 1/2a study, we eagerly await the clinical start of our next-generation, immune evading stealth cell technology with PBCAR19B, which includes modifications designed to enhance CAR T persistence and delay allogeneic immune rejection by T cells and natural killer cells.”

Company-Hosted Conference Call and Web Cast Information

Precision will host a conference call and webcast on Friday, June 4, 2021 at 8:00 a.m. ET to review the most recent interim clinical data for PBCAR0191. The dial-in conference call numbers for domestic and international callers are (866) 996-7202 and (270) 215-9609, respectively. The conference ID number for the call is 5647916. Participants may access the live webcast and the accompanying presentation materials on Precision’s website www.precisionbiosciences.com in the Investors and Media section under Events and Presentations. An archived replay of the webcast will be available on Precision’s website.

About Precision BioSciences, Inc.

Precision BioSciences, Inc. is a clinical stage biotechnology company dedicated to improving life (DTIL) with its wholly proprietary ARCUS^® genome editing platform. ARCUS is a highly specific and versatile genome editing platform that was designed with therapeutic safety, delivery, and control in mind. Using ARCUS, the Company’s pipeline consists of multiple “off-the-shelf” CAR T immunotherapy clinical candidates and several in vivo gene correction therapy candidates to cure genetic and infectious diseases where no adequate treatments exist. For more information about Precision BioSciences, please visit www.precisionbiosciences.com.

Forward Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including, without limitation, statements regarding our clinical development pipeline and interim data announcements. In some cases, you can identify forward-looking statements by terms such as “aim,” “anticipate,” “believe,” “could,” “eligible,” “expect,” “expected,” “should,” “plan,” “intend,” “estimate,” “target,” “mission,” “goal,” “may,” “will,” “would,” “should,” “could,” “target,” “potential,” “potentially,” “promising,” “project,” “predict,” “contemplate,” “potential,” or the negative thereof and similar words and expressions.

Forward-looking statements are based on management’s current expectations, beliefs and assumptions and on information currently available to us. Such statements are subject to a number of known and unknown risks, uncertainties and assumptions, and actual results may differ materially from those expressed or implied in the forward-looking statements due to various important factors, including, but not limited to: our ability to become profitable; our ability to procure sufficient funding and requirements under our current debt instruments and effects of restrictions thereunder; risks associated with raising additional capital; our operating expenses and our ability to predict what those expenses will be; our limited operating history; the success of our programs and product candidates in which we expend our resources; our limited ability or inability to assess the safety and efficacy of our product candidates; our dependence on our ARCUS technology; the initiation, cost, timing, progress, achievement of milestones and results of research and development activities, preclinical or greenhouse studies and clinical or field trials; public perception about genome editing technology and its applications; competition in the genome editing, biopharmaceutical, biotechnology and agricultural biotechnology fields; our or our collaborators’ ability to identify, develop and commercialize product candidates; pending and potential liability lawsuits and penalties against us or our collaborators related to our technology and our product candidates; the U.S. and foreign regulatory landscape applicable to our and our collaborators’ development of product candidates; our or our collaborators’ ability to obtain and maintain regulatory approval of our product candidates, and any related restrictions, limitations and/or warnings in the label of an approved product candidate; our or our collaborators’ ability to advance product candidates into, and successfully design, implement and complete, clinical or field trials; potential manufacturing problems associated with the development or commercialization of any of our product candidates; our ability to obtain an adequate supply of T cells from qualified donors; our ability to achieve our anticipated operating efficiencies at our manufacturing facility; delays or difficulties in our and our collaborators’ ability to enroll patients; changes in interim “top-line” and initial data that we announce or publish; if our product candidates do not work as intended or cause undesirable side effects; risks associated with applicable healthcare, data protection, privacy and security regulations and our compliance therewith; the rate and degree of market acceptance of any of our product candidates; the success of our existing collaboration agreements, and our ability to enter into new collaboration arrangements; our current and future relationships with and reliance on third parties including suppliers and manufacturers; our ability to obtain and maintain intellectual property protection for our technology and any of our product candidates; potential litigation relating to infringement or misappropriation of intellectual property rights; our ability to effectively manage the growth of our operations; our ability to attract, retain, and motivate key executives and personnel; market and economic conditions; effects of system failures and security breaches; effects of natural and manmade disasters, public health emergencies and other natural catastrophic events effects of the outbreak of COVID-19, or any pandemic, epidemic or outbreak of an infectious disease; insurance expenses and exposure to uninsured liabilities; effects of tax rules; risks related to ownership of our common stock and other important factors discussed under the caption “Risk Factors” in our Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2021, as any such risk factors may be updated from time to time in our other filings with the SEC. These filings are accessible on the SEC’s website at www.sec.gov and the Investors & Media page of our website at investor.precisionbiosciences.com.

All forward-looking statements speak only as of the date of this press release and, except as required by applicable law, we have no obligation to update or revise any forward-looking statements contained herein, whether as a result of any new information, future events, changed circumstances or otherwise.

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1</sup> Fludarabine (30 mg/m/day for 3 days) and Cyclophosphamide (500 mg/m²/day for 3 days)

² Fludarabine (30 mg/m/day for 4 days) and Cyclophosphamide (1000 mg/m²/day for 3 days)

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