Precision BioSciences : Statement on Safety of its Allogeneic CAR T Cells

Precision BioSciences, Inc. (Nasdaq: DTIL), a clinical stage biotechnology company using its ARCUS® genome editing platform to develop allogeneic CAR T and in vivo gene editing therapies, issued the following statement about the safety of its allogeneic CAR T cell therapies.

1) Precision BioSciences' allogeneic CAR T cells are made using its proprietary ARCUS genome editing platform designed for precision, specificity, and safety.

2) Precision BioSciences' CAR T cells are the only allogeneic CAR T cells in human clinical trials made with a single gene editing step to specifically avoid the potentially deleterious effects of making multiple edits to T cells.

• It is known in the field that making multiple edits in T cells can result in chromosomal abnormalities. Specifically, it has been shown to be an issue in TCR/CD52 edited cells. As published in Cancer Research[1], "Translocation frequencies ranged from 10^-4 to 2x10^-2 with translocations resulting in acentromeric or dicentromeric chromosomes occurring the least frequently."
• Precision's lymphodepletion strategy does not include an anti-CD52 monoclonal antibody, and therefore does not require editing CD52 in the CAR T cells.

3) In addition, Precision BioSciences believes the oligo-capture method is the most sensitive method available for off-target detection allowing for superior product characterization with respect to gene editing safety. Importantly, this method is used to engineer out off-target editing of the ARCUS nucleases during the research phase of product development.

4) As part of product release testing, Precision BioSciences evaluates chromosomal abnormalities and confirms that the CAR T cells are not transformed.

5) Across four clinical programs in more than 100 patients treated with PBCAR T cells, Precision BioSciences has seen no evidence of chromosomal abnormalities.

Precision BioSciences is actively recruiting patients in ongoing clinical studies of PBCAR0191 (NCT03666000) for patients with relapsed or refractory (R/R) non-Hodgkin lymphoma (NHL) and R/R B-cell acute lymphoblastic leukemia, PBCAR19B (NCT04649112) for patients with R/R NHL, and PBCAR269 (NCT04171843) for patients with R/R multiple myeloma.

Forward-Looking Statements

This statement contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this statement that do not relate to matters of historical fact should be considered forward-looking statements, including, without limitation, statements regarding the potential benefits of a single gene editing step, the sensitivity of off-target detection methods, the manufacture and clinical development of our allogeneic CAR T product candidates, the potential safety and clinical benefit of our allogeneic CAR T product candidates and the evaluation and incidence of chromosomal abnormalities. In some cases, you can identify forward-looking statements by terms such as "aim," "anticipate," "believe," "could," "expect," "should," "plan," "intend," "estimate," "target," "mission," "goal," "may," "will," "would," "should," "could," "target," "potential," "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 June 30, 2021, as any such factors may be updated from time to time in our other filings with the SEC, which 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 statement 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.

[1] Poirot et al, 2015 Cancer Research, 75(18) 3853-64.