Quince Therapeutics said its experimental therapy that delivers steroids through patients’ own red blood cells did not demonstrate efficacy in a pivotal phase 3 study in ataxia-telangiectasia (A-T), a rare inherited disorder affecting the nervous and immune systems. The outcome of the trial led the company to discontinue further clinical development of the program and evaluate next steps.
The study assessed dexamethasone-containing eDSP, also known as EryDex, in patients with A-T. Quince reported that the placebo-controlled phase 3 Neat trial failed to meet both its primary and secondary endpoints. Following the announcement, the company’s shares dropped by more than 90% on Nasdaq, closing at $0.27 per share on Thursday. In a Jan. 29 release, Quince said it will stop clinical development of eDSP and intends to preserve cash while exploring available options.
As of the end of September, Quince reported cash, cash equivalents, and short-term investments totaling $26.3 million. According to its third-quarter report, the company expected those funds to support operations into the second quarter of 2026.
A-T, also known as Louis-Bar syndrome, is caused by mutations in the ATM gene and typically begins in early childhood. Initial symptoms include impaired balance and coordination, followed by the appearance of small clusters of dilated blood vessels on the eyes and skin. The condition affects both the nervous and immune systems, and many patients develop infections and cancer over time. Most individuals with A-T live up to about 30 years of age. Citing IQVIA data, Quince said approximately 4,600 patients in the United States have been diagnosed with the disease. There are currently no approved therapeutic treatments for A-T.
Corticosteroids such as dexamethasone have previously shown some benefit in improving neurological function in A-T, but long-term use has been limited by toxicity. Quince developed eDSP using its autologous intracellular drug encapsulation (AIDE) platform to address that issue.
The approach involves collecting a patient’s red blood cells, loading them with dexamethasone sodium phosphate through porous membranes, and reinfusing them so the drug is released gradually into circulation. The goal was to reduce toxicity associated with frequent high-dose steroid treatment while maintaining anti-inflammatory effects.
The Neat trial enrolled 105 patients, including 83 children between the ages of 6 and 9, in the primary analysis population. Participants received six infusions administered every 21 to 30 days. The primary endpoint measured the change from baseline to Month 6 using the Rescored modified International Cooperative Ataxia Rating Scale (RmICARS). The mean change was 0.94 in the eDSP group and 2.24 in the placebo group, resulting in a p-value of 0.0851. Higher RmICARS scores indicate greater disease severity.
The trial was powered at approximately 90% to detect a statistically significant difference between eDSP and placebo on the primary endpoint, according to comments made by Quince Chief Executive Officer and Chief Medical Officer Dirk Thye, M.D., in the company’s third-quarter report. At that time, Thye noted that an independent data monitoring committee had recommended continuation of the study following a safety analysis and that all trial participants had elected to enroll in an open-label extension study.
The secondary endpoint, which evaluated changes in the Clinical Global Impression of Severity from baseline to Month 6, also did not reach statistical significance, with a p-value of 0.522.
“eDSP was generally well tolerated, and there were no clinically meaningful safety concerns identified,” Quince said.
The Neat study followed a previous phase 3 trial, Attest, which also failed to demonstrate a benefit for the intra-erythrocyte delivery approach across a broad age range. A subgroup analysis from that trial indicated that children aged 6 to 9 years appeared to benefit from a higher dose of the drug. Study authors also cited the COVID-19 pandemic as a potential factor, noting that some patients experienced delayed or missed treatments.
Impact on Quince Therapeutics’ Development Strategy
Following the trial failure, Quince Therapeutics announced plans to discontinue further development of eDSP for Ataxia-Telangiectasia. The company stated it will evaluate strategic alternatives, including pipeline reassessment and cost-containment measures, as Quince Therapeutics works to preserve capital after the unsuccessful Phase 3 outcome.
