Aldeyra Therapeutics · reproxalap · Apr 2025 → Mar 2026
What changed between the FDA's 2025 and 2026 letters on reproxalap?
From one study's analysis and a request for another study, to the “inconsistency of study results” and, by Aldeyra's account, no request for more. The finding's wording widened from symptoms to signs and symptoms.
EphemerisX Research · Published · 5 source documents · 2 min read
Short answer
The 2025 letter centred on Study 030 and asked for at least one more adequate and well-controlled study. The 2026 letter, as Aldeyra's 8-K quotes it, cited the inconsistency of study results and said the totality of evidence from the completed trials does not support effectiveness; by the company's account it recommended exploring the reasons for failure in certain trials and did not ask for more trials. Its finding refers to signs and symptoms of dry eye disease; the 2025 finding referred to ocular symptoms.
What the evidence shows
Page 1 of each letter, where the finding is stated, is a scanned image with no text layer. The wording below is Aldeyra's quotation of it, except where marked as the letter's own page 2 or 3.
2025, as the 8-K quotes it: the NDA failed to demonstrate efficacy in adequate and well controlled studies in treating ocular symptoms associated with dry eyes
8-K · Apr 3, 2025. The letter's page 2: You should conduct at least one additional adequate and well controlled study
FDA · Apr 2, 2025 · p. 2.
2026, as the 8-K quotes it: the application has failed to demonstrate efficacy in adequate and well controlled studies in the treatment of signs and symptoms of dry eye disease
8-K · Mar 17, 2026, and the inconsistency of study results raises serious concerns about the reliability and meaningfulness of the positive findings
8-K · Mar 17, 2026. The 8-K reports: The FDA recommended that the reasons for failure in certain trials be explored, and that populations or certain conditions in which reproxalap may be effective be identified
8-K · Mar 17, 2026, and The FDA did not recommend conducting additional trials or request submission of additional confirmatory evidence
8-K · Mar 17, 2026. The March 2026 8-K does not say which trials the FDA's recommendation about reasons for failure refers to. 8-K · searched
What changed
The scope of the finding: in treating ocular symptoms associated with dry eyes
8-K · Apr 3, 2025 in 2025; in the treatment of signs and symptoms of dry eye disease
8-K · Mar 17, 2026 in 2026. The NDA itself, Aldeyra said in 2024, was for the treatment of signs and symptoms of dry eye disease
8-K · Oct 3, 2024; its April 2025 release notes that under draft FDA guidance efficacy in dry eye disease may be demonstrated with two symptom trials and two sign trials
8-K · Apr 3, 2025.
What was asked: in 2025, at least one additional adequate and well controlled study
FDA · Apr 2, 2025 · p. 2; in 2026, by Aldeyra's account, no additional trials, and that the reasons for failure in certain trials be explored
8-K · Mar 17, 2026.
What was found: in 2025, one study's analysis (The Agency finds the Study 030 primary efficacy endpoint analysis problematic
FDA · Apr 2, 2025 · p. 2); in 2026, the evidence as a whole (totality of evidence from the completed clinical trials does not support the effectiveness of the product
8-K · Mar 17, 2026).
What stayed the same on the letters' readable pages: each says A resubmission must fully address the deficiency listed in this letter
FDA · Apr 2, 2025 · p. 3 (2025) and A resubmission must fully address the deficiency listed in this letter
FDA · Mar 16, 2026 · p. 2 (2026), and each reserves comment on labeling: We reserve comment on the proposed labeling until the application is otherwise adequate
FDA · Mar 16, 2026 · p. 2. Aldeyra reported no safety or manufacturing issues both times: no manufacturing or safety issues with reproxalap were identified
8-K · Apr 3, 2025 (2025); no safety or manufacturing concerns were identified
8-K · Mar 17, 2026 (2026).
Follow the thread
- Did the FDA's 2025 letter ask Aldeyra for the same study as its 2023 letter?“At least one additional adequate and well controlled study”
- Did Aldeyra's second chamber trial answer the FDA's 2025 objections?“Inconsistency of study results”
- Was the FDA negotiating reproxalap's label when it issued the second letter?“We reserve comment on the proposed labeling”
- What is Aldeyra appealing, and what had the FDA's 2026 letter recommended?The FDA's 2026 recommendations
This investigation connects to
- When is one trial enough? How the FDA weighed the evidence in three programsCross-investigation · Comparable evidence · with Outlook Therapeutics, Replimune
The documents, by date
The passages quoted
Aldeyra Therapeutics Form 8-K, filed October 3, 2024
today announced the resubmission of a New Drug Application (NDA) to the U.S. Food and Drug Administration (FDA) for topical ocular reproxalap, an investigational new drug candidate, for the treatment of signs and symptoms of dry eye disease.Open at the source →
FDA Complete Response Letter, April 2, 2025 · page 2
You used Visit 2 and Visit 4 DEC results as the dependent variable and performed linear contrasts to obtain treatment differences between Visit 4 and Visit 2 results. The Agency finds the Study 030 primary efficacy endpoint analysis problematic, and we do not find the study results to be robust.Open at the source →
FDA Complete Response Letter, April 2, 2025 · page 2
You should conduct at least one additional adequate and well controlled study to demonstrate a positive effect on the treatment of ocular symptoms of dry eye. In the conduct of this study, you should not make changes to the protocol or the statistical analysis plan after the first subject is enrolled in the study without expressed agreement by the FDA.Open at the source →
FDA Complete Response Letter, April 2, 2025 · page 3
A resubmission must fully address the deficiency listed in this letter and should be clearly marked with "RESUBMISSION" in large font, bolded type at the beginning of the cover letter of the submission. The cover letter should clearly state that you consider this resubmission a complete response to the deficiency outlined in this letter. A partial response to this letter will not be processed as a resubmission and will not start a new review cycle.Open at the source →
Aldeyra Therapeutics Form 8-K, filed April 3, 2025
Per draft FDA dry eye disease guidance, to be considered for regulatory approval in the United States, efficacy in dry eye disease may be demonstrated with two symptom trials and two sign trials.Open at the source →
Aldeyra Therapeutics Form 8-K, filed April 3, 2025
Although no manufacturing or safety issues with reproxalap were identified, the FDA stated in the letter that the NDA “failed to demonstrate efficacy in adequate and well controlled studies in treating ocular symptoms associated with dry eyes” and that “at least one additional adequate and well controlled study to demonstrate a positive effect on the treatment of ocular symptoms of dry eye” should be conducted. The letter identified concerns with the data from the trial submitted to the NDA that may have affected interpretation of the results, which the FDA stated may be related to methodological issues, including a difference in baseline scores across treatment arms.Open at the source →
FDA Complete Response Letter, March 16, 2026 · page 2
CARTON AND CONTAINER LABELING We reserve comment on the proposed labeling until the application is otherwise adequate.Open at the source →
FDA Complete Response Letter, March 16, 2026 · page 2
A resubmission must fully address the deficiency listed in this letter and should be clearly marked with "RESUBMISSION" in large font, bolded type at the beginning of the cover letter of the submission. The cover letter should clearly state that you consider this resubmission a complete response to the deficiency outlined in this letter. A partial response to this letter will not be processed as a resubmission and will not start a new review cycle.Open at the source →
Aldeyra Therapeutics Form 8-K, filed March 17, 2026
The March 2026 8-K does not say which trials the FDA's recommendation about reasons for failure refers to.
Open the document →Aldeyra Therapeutics Form 8-K, filed March 17, 2026
The FDA recommended that the reasons for failure in certain trials be explored, and that populations or certain conditions in which reproxalap may be effective be identified. The FDA did not recommend conducting additional trials or request submission of additional confirmatory evidence. As such, Aldeyra does not currently expect to pursue additional clinical trials, and intends to expeditiously request a Type A meeting to understand the actions needed for NDA approval.Open at the source →
Aldeyra Therapeutics Form 8-K, filed March 17, 2026
Consistent with prior NDA reviews of reproxalap, no safety or manufacturing concerns were identified.Open at the source →
Aldeyra Therapeutics Form 8-K, filed March 17, 2026
The CRL stated that there is “a lack of substantial evidence consisting of adequate and well-controlled investigations … that the drug product will have the effect it purports or is represented to have under the conditions of use prescribed, recommended, or suggested in its proposed labeling” and that “the application has failed to demonstrate efficacy in adequate and well controlled studies in the treatment of signs and symptoms of dry eye disease.” The letter also stated that the “inconsistency of study results raises serious concerns about the reliability and meaningfulness of the positive findings” and that the “totality of evidence from the completed clinical trials does not support the effectiveness of the product.”Open at the source →