Phase 3 clinical trial results for ST-100 (vezocolmitide) ophthalmic solution, a novel dry eye candidate

ST-100's ability to repair the ocular collagen restores the homeostatic function on the ocular surface, thus alleviating the effects of dry eye disease.

(Image credit: ©Sanhanat—stock.adobe.com)

Stuart Therapeutics, Inc. announced the initial results of its phase 3 clinical trial evaluating ST-100 (vezocolmitide) ophthalmic solution for treating dry eye disease.

The topline results enumerated in the company’s press release are as follows:

• The results highlight ST-100's potential for fast-acting healing of ocular surface damage caused by dry eye disease.
• The therapeutic effects were observed rapidly, with relief apparent within 2 to 4 days of treatment for both signs and symptoms.
• ST-100 is uniquely positioned to address unmet patient needs compared to currently approved treatments.
• The findings will help guide the design of a second phase 3 study.

The press release went on to describe that ST-100 is part of a novel drug class of collagen mimetic peptides derived from the company's patented and proprietary PolyCo technology platform, which have a unique mechanism of action. ST-100 works by targeting and repairing damaged collagen, which differs from other dry eye therapies. Collagen plays a key role in dry eye disease, and collagen damage during the development of dry eye disease is part of an inflammatory cycle and loss of tissue integrity that interferes with normal function and cell signaling, particularly in the corneal and conjunctival epithelium. ST-100's ability to repair the ocular collagen restores the homeostatic function on the ocular surface, thus alleviating the effects of dry eye disease.

Stuart Therapeutics President and CEO Eric Schlumpf commented, "We are very pleased with the outcome of the trial. While additional study is required, the underlying data and the clinically meaningful results from this trial strongly suggest that ST-100, as the first drug candidate in a novel therapeutic class, can address the critical unmet needs in dry eye disease: a fast, effective, and comfortable dry eye topical drop that gives patients rapid relief they can notice and appreciate."

Phase 3 study design and results

The study was a 29-day randomized, double-blind, vehicle-controlled trial. The primary endpoint was a significant increase in the proportion of patients with improvement that exceeded 10 mm over baseline in the Schirmer tear test score (Schirmer's Responder Rate [SRR]). ST-100's SRR performance exceeded that of its phase 2 outcome¹ but did not reach statistical significance, as vehicle performed better than in the phase 2 trial.

ST-100 achieved statistically significant improvement in fluorescein staining with onset at week 1 in multiple regions of the eyes of the study subjects. The investigators saw clinically meaningful (>20%) improvement on day 4. The magnitude of the stain improvement at week 1 vs. vehicle was greater than any reported result for any approved dry eye disease therapy or product.

The visual function improved significantly compared with placebo on day 2, further reinforcing ST-100's potential to provide fast-acting resolution of dry eye signs and symptoms, according to the press release.

According to Jodi Luchs, MD, Stuart Therapeutics chief medical officer, "As a practicing ophthalmologist, I am impressed by the clinical achievements and speed of onset of the therapeutic effects of ST-100 in Stuart's phase 3 trial, which suggest rapid ocular surface healing and treatment effects that appear to be considerably greater than those seen with currently approved dry eye disease therapeutics. Based on these study results, I believe ST-100 has the potential to greatly enhance the treatment of dry eye disease and has significant promise in treating other debilitating diseases affecting the cornea."

Stuart Therapeutics is finalizing a plan for an additional clinical trial using the results from the present phase 3 trial to help guide the trial design. The company also intends to engage with the FDA to confirm the design of this additional trial, and the regulatory path to approval of ST-100.

Reference

Baratta RO, Schlumpf E, Del Buono BJ, DeLorey S, Ousler G, Calkins DJ. A phase 2 trial to test safety and efficacy of ST-100, a unique collagen mimetic peptide ophthalmic solution for dry eye disease. Ophthalmol Sci. 2023;4:100451. doi:10.1016/j.xops.2023.100451