Ocuvex Therapeutics, Inc. has resubmitted a complete response letter (CRL) to the FDA for its new drug application (NDA) of PDP-716 (brimonidine tartrate 0.35%).
The news was shared by Sun Pharma Advanced Research Company Ltd. (SPARC), which is collaborating with Ocuvex on the therapeutic’s clinical development.
Let’s begin with SPARC.
First: This clinical-stage bio-pharmaceuticals company is not the same as Sun Pharma.
- In fact, SPARC demerged from Sun Pharma in 2007 to focus on novel drug discovery and advanced drug delivery systems.
And in 2021, the company kicked off a partnership with then-Visiox Pharmaceuticals (before its 2024 merger with Ocuvex) to develop two ophthalmic drugs—one of which is PDP-716.
Tell me about that partnership.
Based on the company’s original license agreement with then-Visiox—and pending U.S. regulatory approval of PDP-716—SPARC would be eligible to receive:
- An upfront payment, milestone payments, and royalty on sales
- 10% equity in then-Visiox
Got it. Now to Ocuvex.
The privately-held, early-stage ophthalmic biotechnology is developing and commercializing a portfolio of therapeutics targeting diseases—specifically: glaucoma and ocular hypertension (OHT).
And as we mentioned: Ocuvex merged with Visiox in 2024 (as did Onconetix, Inc. earlier this year).
- Most notable in its portfolio: OMLONTI (omidenepag isopropyl ophthalmic solution) 0.002%, indicated for reducing intraocular pressure (IOP) in patients with open-angle glaucoma (OAG) or ocular hypertension (OHT).
- Though the drug was FDA approved in 2022, it was later discontinued and is currently marketed by Ocuvex as “coming soon.”
Let’s move on to PDP-716 …
Originally developed by SPARC, PDP-716 (brimonidine tartrate) 0.35% is under clinical development for the treatment of OAG and OHT as a once-daily eye drop.
Key to its formulation is SPARC’s patented TearAct technology:
- What this does: Utilizing resin microparticles in a complex suspension, this tech is designed to provide a slow, consistent, and sustained drug delivery by:
- Improving drug bioavailability and dosing frequency
- Prolonging drug release and exposure
What do we know about its NDA submission history?
Ocuvex originally submitted an NDA for PDP-716 to the FDA in October 2025, which the federal agency initially accepted that December.
However: Fast forward to July 2023, the FDA issued a CR in regards to unresolved facility inspection-related conditions identified at a third-party active pharmaceutical ingredient (API) manufacturing facility.
Now tell me about this resubmission.
Broadly speaking: A company resubmitting a CRL indicates a formal response to the FDA in an attempt to correct any deficiencies that were identified and used to support the federal agency’s rejection of a company’s submission for regulatory approval.
In this case: Ocuvex resubmitted its CRL to address those aforementioned July 2023 concerns.
Do we know what these conditions were?
Nope, not specifically.
So what does this have to do with PDP-716?
The conditions observed were identified at the manufacturing facility used to develop the ophthalmic solution.
- However, SPARC emphasized that “the FDA did not raise any concerns related to the efficacy or safety” of PDP-716 in that July 2023 letter.
… and yet the candidate has been on hold?
Indeed. But with Ocuvex’s new resubmission underway, it’s possible that regulatory movement for the ophthalmic solution may be on the horizon.
- SPARC shared that it will update investors on next steps (and potential developments) “after the FDA has determined that the response submission is complete.”
Translation: The waiting period begins—stay tuned!