Aldeyra Therapeutics Reaches Agreement with the US Food and Drug Administration for the Use of RASP as an Objective Sign for the Treatment of Dry Eye Disease

Aldeyra Therapeutics Reaches Agreement with the US Food and Drug Administration for the Use of RASP as an

Objective Sign for the Treatment of Dry Eye Disease

LEXINGTON, Mass., June 4, 2020 Aldeyra Therapeutics, Inc.

(Nasdaq: ALDX) (Aldeyra), a clinical-stage biotechnology company focused on the development of novel therapies with the potential to improve the lives of patients with immune-mediated diseases, today announced that, based on preliminary written

comments and meeting discussion, agreement has been reached with the US Food and Drug Administration (FDA) for the use of RASP (reactive aldehyde species) as an objective sign for the treatment of dry eye disease.

RASP are pre-cytokine pro-inflammatory mediators that are elevated in the

tears of patients with dry eye disease,1 and correlate with dry eye disease symptoms and signs.2 In a Phase 2a dry eye disease clinical trial,

Aldeyra s investigational first-in-class RASP inhibitor reproxalap demonstrated reduction in tear RASP levels following 28 days of treatment. In in vitro

studies, RASP were eliminated within 60 to 90 minutes when exposed to reproxalap at equimolar concentrations. Reproxalap, when administered topically to the eye, is thought to be more than 500-fold in excess

of tear RASP levels, and has demonstrated consistent statistically significant and clinically relevant activity in dry eye disease, allergic conjunctivitis, and other forms of ocular inflammation across numerous Phase 2 and Phase 3 clinical trials.

Representing the first novel objective sign for the treatment in dry eye disease in over a decade, RASP are critical mediators of

inflammation, stated Todd C. Brady, M.D., Ph.D., President and Chief Executive Officer of Aldeyra. We look forward to continuing to advance reproxalap, our novel RASP inhibitor in Phase 3 clinical trials for dry eye disease and allergic

conjunctivitis, toward NDA filing.

Aldeyra expects to provide an update on clinical development plans and remaining NDA requirements for

reproxalap in dry eye disease following receipt of FDA meeting minutes, which are anticipated in July 2020.

About Aldeyra Therapeutics

Aldeyra Therapeutics is a clinical-stage biotechnology company focused on the development of novel therapies with the potential to improve the lives of

patients with immune-mediated diseases. Two of the company s lead compounds, reproxalap and ADX-629, target reactive aldehyde species (RASP), which are elevated in ocular and systemic inflammatory

disease, leading to elevated levels of cytokine release via activation of a broad array of inflammatory factors, including NF-kB, inflammasomes, and Scavenger Receptor A. Reproxalap is being evaluated in Phase

3 clinical trials in patients with dry eye disease and allergic conjunctivitis. The company s clinical pipeline also includes ADX-2191, a dihydrofolate reductase inhibitor in Phase 3 testing for

proliferative vitreoretinopathy, and ADX-1612, a chaperome inhibitor in Phase 2 testing for COVID-19 and ovarian cancer. For more information, visit

Safe Harbor Statement

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

Aldeyra s strategy, future operations, prospects, plans, and objectives and Aldeyra s plans and expectations for its product candidates, including reproxalap in dry eye disease and allergic conjunctivitis. Aldeyra intends such

forward-looking statements to be covered by the safe harbor provisions for forward-looking statements contained in Section 21E of the Securities Exchange Act of 1934 and the Private Securities Litigation Reform Act of 1995. In some cases, you

can identify forward-looking statements by terms such as, but not limited to, may, might, will, objective, intend, should, could, can, would,

expect, believe, anticipate, project, on track, scheduled, target, design, estimate, predict, potential,

aim, plan or the negative of these terms, and similar expressions intended to identify forward-looking statements. Such forward-looking statements are based upon current expectations that involve risks, changes in

circumstances, assumptions and uncertainties. Aldeyra is at an early stage of development and may not ever have any products that generate significant revenue. All of Aldeyra s development timelines may be subject to adjustment depending on

recruitment rate, regulatory review, preclinical and clinical results, and other factors that could delay the initiation or completion of clinical trials. The FDA is not bound by written

FDA comments or meeting discussions and such comments and discussions do not necessarily reflect the FDA s final decision, which is expected to be set forth in the final meeting minutes. As

a result of the COVID-19 pandemic, clinical site availability, staffing, and patient recruitment have been negatively affected and the timelines to complete our clinical trials may be delayed. Important

factors that could cause actual results to differ materially from those reflected in Aldeyra s forward-looking statements include, among others, later developments with the FDA that may be inconsistent with Aldeyra s expectations and

beliefs, including inconsistent conclusions reflected in the final meeting minutes from the FDA, the timing of enrollment, commencement and completion of Aldeyra s clinical trials, the timing and success of preclinical studies and clinical

trials conducted by Aldeyra and its development partners; updated or refined data based on Aldeyra s continuing review and quality control analysis of clinical data, Aldeyra s ability to design clinical trials with protocols and endpoints

acceptable to applicable regulatory authorities; delay in or failure to obtain regulatory approval of Aldeyra s product candidates; the ability to maintain regulatory approval of Aldeyra s product candidates, and the labeling for any

approved products; the risk that prior results, such as signals of safety, activity or durability of effect, observed from preclinical or clinical trials, will not be replicated or will not continue in ongoing or future studies or trials involving

Aldeyra s product candidates; the scope, progress, expansion, and costs of developing and commercializing Aldeyra s product candidates; the current and potential future impact of the COVID-19

pandemic on our business, results of operations and financial position; uncertainty as to Aldeyra s ability to commercialize (alone or with others) Aldeyra s product candidates following regulatory approval, if any; the size and growth of

the potential markets and pricing for Aldeyra s product candidates and the ability to serve those markets; Aldeyra s expectations regarding Aldeyra s expenses and revenue, the sufficiency or use of Aldeyra s cash resources and

needs for additional financing; political, economic, legal, social and health risks, including the recent COVID-19 outbreak and subsequent public health measures, that may affect Aldeyra s business or the

global economy; the rate and degree of market acceptance of any of Aldeyra s product candidates; Aldeyra s expectations regarding competition; Aldeyra s anticipated growth strategies; Aldeyra s ability to attract or retain key

personnel; Aldeyra s limited sales and marketing infrastructure; Aldeyra s ability to establish and maintain development partnerships; Aldeyra s ability to successfully integrate acquisitions into its business; Aldeyra s

expectations regarding federal, state and foreign regulatory requirements; regulatory developments in the United States and foreign countries; Aldeyra s ability to obtain and maintain intellectual property

protection for its product candidates; the anticipated trends and challenges in Aldeyra s business and the market in which it operates; and other factors that are described in the Risk

Factors and Management s Discussion and Analysis of Financial Condition and Results of Operations sections of Aldeyra s Annual Report on Form 10-K for the year ended

December 31, 2019 and Aldeyra s Quarterly Report on Form 10-Q for the quarter ended March 31, 2020, which are on file with the Securities and Exchange Commission (SEC) and available on the

SEC s website at www.sec.gov.

In addition to the risks described above and in Aldeyra s other filings with the SEC, other unknown or

unpredictable factors also could affect Aldeyra s results. No forward-looking statements can be guaranteed, and actual results may differ materially from such statements. The information in this release is provided only as of the date of this

release, and Aldeyra undertakes no obligation to update any forward-looking statements contained in this release on account of new information, future events, or otherwise, except as required by law.