LogicBio Therapeutics : January 2021 Corporate Presentation

Delivering differentiated genomic medicines to transform the lives of patients suffering from devastating diseases

January 2021

2

Forward-looking statements

This presentation contains "forward-looking statements" within the meaning of the federal securities laws. These forward-looking statements are not statements of historical facts and are based on management's beliefs and assumptions and on information currently available to management. Forward-looking statements include information concerning the Company's business strategy and the design, progression and timing of its preclinical trials and clinical trials, including information related to the Company's plans to initiate, advance and complete its planned SUNRISE Phase 1/2 clinical trial of LB-001 in methylmalonic acidemia ("MMA").

Forward-looking statements generally can be identified by terms such as "expects," "anticipates," "believes," "could," "seeks," "estimates," "intends," "may," "plans," "potential," "predicts," "projects," "should," "will," "would" or similar expressions and the negatives of those terms, and similar expressions and comparable terminology intended to identify forward-looking statements. The Company's operations involve risks and uncertainties, many of which are outside its control, and any one of which, or combination of which, could materially affect its results of operations and whether the forward-looking statements ultimately prove to be correct. Factors that may materially affect the Company's results of operations and whether these forward-looking statements prove to be correct include, among other things, that preclinical testing may not be predictive of the results or success of ongoing or later preclinical or clinical trials, that the development of the Company's product candidates and new platforms may take longer and/or cost more than planned and that the identification of new product candidates may take longer than planned, as well as those listed in the Company's Annual Report on Form 10-K filed on March 16, 2020 with the Securities and Exchange Commission ("SEC"), the Company's Quarterly Report on Form 10-Q filed on May 11, 2020, and the Company's subsequent Quarterly Reports on Form 10-Q and other filings with the SEC. In particular, the impact of the COVID-19 pandemic on the Company's ability to progress with its research,

development, manufacturing and regulatory efforts, including the Company's plans to initiate, advance and complete its Phase 1/2 clinical trial for LB-001 in MMA, and the value of and market for the Company's common stock, will depend on future developments that are highly uncertain and cannot be predicted with confidence at this time, such as the ultimate duration of the pandemic, travel restrictions, quarantines, social distancing and business closure requirements in the United States and in other countries, and the effectiveness of actions taken globally to contain and treat the disease. Except as required by law, the Company assumes no obligation to update these forward-looking statements publicly, or to update the reasons actual results could differ materially from those anticipated in the forward-looking statements, even if new information becomes available in the future.

This presentation also contains estimates, projections and other information concerning the Company's industry, business and the market for its products and services, as well as data regarding market research, estimates and forecasts prepared by the Company's management. Information that is based on estimates, forecasts, projections, market research or similar methodologies is inherently subject to uncertainties and actual events or circumstances may differ materially from events and circumstances reflected in this information. Certain data in this presentation was obtained from various external sources, and neither the Company nor its affiliates, advisers or representatives has verified such data with independent sources. Accordingly, neither the Company nor any of its affiliates, advisers or representatives makes any representations as to the accuracy or completeness of that data or to update such data after the date of this presentation. Such data involves risks and uncertainties and is subject to change based on various factors.

3 LogicBio overview

Clinical stage genomic medicine company aiming to deliver transformational therapies to patients with high unmet needs

Differentiated gene editing platform to provide a durable treatment through precise gene insertion

Innovative synthetic capsids to address limitations of current generation gene therapy approaches

Open IND for MMA program with initial clinical proof of concept data expected in 2021

Core technology platform with the potential to address a broad portfolio of genetic diseases

4 LogicBio overview

Pioneering a new class of genomic medicines

Combining two innovative platforms to tackle difficult to treat diseases

GeneRide™ : a differentiated gene editing

platform

• Nuclease free leveraging homologous recombination
• Durable therapeutic transgene expression driven by endogenous promoters
• Site-specificintegration
• Modular and broadly applicable

Next-Gen AAV capsid platform

• Tissue tropism assessed in clinically predictive models developed by CMRI*
• High functional transduction
• Low immunogenicity
• High manufacturing yield

* Children Medical Research Institute - Sydney, Australia