Solid Biosciences Reports Third Quarter 2020 Financial Results and Provides Business Update IGNITE DMD clinical trial expected to resume dosing in the first quarter of 2021 -Collaboration with Ultragenyx creates opportun

Solid Biosciences Reports Third Quarter 2020 Financial Results and Provides Business Update

IGNITE DMD clinical trial expected to resume dosing in the first quarter of 2021

-Collaboration with Ultragenyx creates opportunities to develop additional gene therapies for Duchene muscular dystrophy-

Enhanced cash position resulting from Ultragenyx collaboration and fund-raising activity expected to provide financial runway into

the second half of 2021

Conference call and webcast scheduled for 8:30 AM ET

CAMBRIDGE, Mass., November 5, 2020 Solid Biosciences Inc. (Nasdaq: SLDB), a life sciences company focused on advancing

meaningful therapies for Duchenne muscular dystrophy (Duchenne), today reported financial results for the third quarter ended September 30, 2020 and provided a business update.

With the FDA s lifting of the clinical hold on the IGNITE DMD trial, we are well underway in completing the activities necessary to resume dosing,

which we expect will occur in the first quarter of 2021, said Ilan Ganot, Chief Executive Officer, President and Co-Founder of Solid Biosciences. This important event and establishing a

strategic collaboration with Ultragenyx to develop additional gene therapies for Duchenne mark important progress toward our goal of improving the lives of patients living with Duchenne. We are also increasing production of SGT-001 using our improved manufacturing process in support of dosing additional patients in 2021. Additionally, we strengthened our balance sheet with additional capital from the Ultragenyx collaboration and

our recent at-the-market, or ATM, equity financing, both of which will support our planned clinical advancement of

Financial Highlights

Research and development expenses

for the third quarter of 2020 were $16.0 million, compared to $22.8 million for the third quarter of 2019. Research and development expenses for the first nine months of 2020 were $49.2 million, compared

to $67.7 million for the first nine months of 2019. The decrease was primarily attributable to a reduction in personnel and facility related expenses as a result of the restructuring that occurred in January 2020, as well as lower

manufacturing costs and a decrease in costs related to other product candidates as the Company focuses on advancing SGT-001.

General and administrative expenses for the third quarter of 2020 were $5.2 million, compared

to $6.9 million for the third quarter of 2019. General and administrative expenses for the first nine months of 2020 were $16.0 million, compared to $19.3 million for the first nine months of 2019. The decrease was

primarily attributable to decreased personnel costs and corporate expenses partially due to the restructuring that occurred in January 2020.

the third quarter of 2020 was $21.2 million, compared to $29.3 million for the third quarter of 2019. Net loss for the first nine months of 2020 was $66.9 million, compared to $85.4 million for the first

nine months of 2019.

Solid had $24.8 million in cash and cash equivalents as of September 30, 2020. The Company expects that its cash and

cash equivalents, combined with proceeds of $40 million from the issuance and sale of shares of common stock to Ultragenyx and the net proceeds of $23.2 million from the ATM Sale will enable Solid to fund its operating expenses into the

second half of 2021.

will host a webcast and conference call to discuss Solid s third quarter 2020 financial results and business update today, November 5, 2020, at 8:30 AM ET.

A live webcast of the call will be available on the Company s website at www.solidbio.com under the News & Events tab in the

Investor Relations section, or by clicking here. Participants may also access the call, by dialing 866-763-0341 for domestic callers or 703-871-3818 for international callers.

The archived webcast will be available

for in the News and Events section of the Company s website.

Solid s SGT-001 is a novel adeno-associated viral (AAV) vector-mediated gene transfer therapy designed to address

the underlying genetic cause of Duchenne. Duchenne is caused by mutations in the dystrophin gene that result in the absence or near absence of dystrophin protein. SGT-001 is a systemically administered

candidate that delivers a synthetic dystrophin gene, called microdystrophin, to the body. This microdystrophin encodes for a functional protein surrogate that is expressed in muscles and stabilizes essential associated proteins, including neuronal

nitric oxide synthase nNOS. Data from Solid s preclinical program suggests that SGT-001 has the potential to slow or stop the progression of Duchenne, regardless of genetic mutation or disease stage.

SGT-001 is based on pioneering research in dystrophin biology by Dr. Jeffrey Chamberlain of the University of

Washington and Dr. Dongsheng Duan of the University of Missouri. SGT-001 has been granted Rare Pediatric Disease Designation, or RPDD, and Fast Track Designation in the United States and Orphan Drug

Designations in both the United States and European Union.

About Solid Biosciences

Solid Biosciences is a life sciences company focused on advancing transformative treatments to improve the lives of patients living with Duchenne.

Disease-focused and founded by a family directly impacted by Duchenne, our mandate is simple yet comprehensive work to address the disease at its core by correcting the underlying mutation that causes Duchenne with our lead gene therapy

candidate, SGT-001. For more information, please visit www.solidbio.com.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995,

including statements regarding the timing and ability of the Company to resume dosing and move the IGNITE DMD clinical trial forward, the safety or potential efficacy of SGT-001, the sufficiency of the

Company s cash and cash equivalents to fund its operations, potential milestone payments or royalty payments in connection with the Ultragenyx collaboration and other statements containing the words anticipate, believe,

continue, could, estimate, expect, intend, may, plan, potential, predict, project, should, target,

would, working and similar expressions. Any forward-looking statements are based on management s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual

results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. These risks and uncertainties include, but are not limited to, risks associated with the Company s ability to resume and/or

continue IGNITE DMD on the timeline expected or at all; obtain and maintain necessary approvals from the FDA and other regulatory authorities; obtain and maintain the necessary approvals from investigational review boards at IGNITE DMD clinical

trial sites and the IGNITE DMD independent data safety monitoring board; enroll patients in IGNITE DMD; continue to advance SGT-001 in clinical trials; replicate in clinical trials positive results found in

preclinical studies and earlier stages of clinical development; advance the development of its product candidates under the timelines it anticipates in current and future clinical trials; successfully optimize and scale its manufacturing process;

obtain, maintain or protect intellectual property rights related to its product candidates; compete successfully with other companies that are seeking to develop DMD/Duchenne treatments and gene therapies; manage expenses; and raise the substantial

additional capital needed, on the timeline necessary, to continue development of SGT-001, achieve its other business objectives and continue as a going concern. For a discussion of other risks and

uncertainties, and other important factors, any of which could cause the Company s actual results to differ from those contained in the forward-looking statements, see the Risk Factors section, as well as discussions of potential

risks, uncertainties and other important factors, in the Company s most recent filings with the Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent the Company s views as

of the date hereof and should not be relied upon as representing the Company s views as of any date subsequent to the date hereof. The Company anticipates that

subsequent events and developments will cause the Company s views to change. However, while the Company may elect to update these forward-looking statements at some point in the future, the

Company specifically disclaims any obligation to do so.

Solid Biosciences Inc.

Condensed Consolidated Statements of Operations

(unaudited, in thousands, except share and per share data)

Solid Biosciences Inc.

Condensed Consolidated Balance Sheets

(unaudited, in thousands, except share and per share data)