Eos SENOLYTIX, Inc. filed a Form 425 on October 30, 2026, announcing early interim results from an aged-rat study of its lead geropeptide PTC-2105 conducted at the Albert Einstein College of Medicine's BIO-VITAL Program Preclinical Testing Core, filed by Pulmatrix, Inc. pursuant to Rule 425 under the Securities Act of 1933.

Key Highlights

  • Motor performance preserved: In super-aged male rats, Rotarod latency at Week 16 remained near baseline with PTC-2105 0.5 mg/kg once weekly, compared with an approximately -76% aging-related decline with vehicle (difference of 78.4 percentage points; p=0.012; n=3 and n=4, respectively).
  • Fat mass reduction: At Week 8, fat mass decreased 14.5% from baseline with PTC-2105 12.5 mg/kg once weekly, compared with 8.2% with vehicle (difference of 6.3 percentage points; p=0.018; n=8 per group).
  • Study scale: Of six planned cohorts, the oldest (n=39 rats enrolled) has reached the 16-week mid-study time point; 167 aged and 62 young rats remain enrolled and progressing through the study.
  • Tolerability: According to the company, PTC-2105 "has been well tolerated, and no adverse safety signals have been observed in any animals in these studies" to date.
  • IND-enabling work underway: Non-GLP dose-range-finding toxicology studies of PTC-2105 in rats and dogs have begun in preparation for GLP toxicology, with first-in-human trials targeted for 2027, subject to IND clearance.
  • Second-species context: The company described the results as "directionally consistent" with findings previously observed in naturally aged 75- to 80-week-old mice.

Interim Aged-Rat Data for PTC-2105 at Einstein's BIO-VITAL Facility

According to the filing, Eos SENOLYTIX is conducting a 32-week study at the BIO-VITAL Program Preclinical Testing Core of the Albert Einstein College of Medicine in the Bronx, New York, under a fee-for-service agreement. The study evaluates two once-weekly subcutaneous doses of PTC-2105 (0.5 and 12.5 mg/kg) against vehicle control across multiple age cohorts, with assessments at eight-week intervals across five time points. Endpoints include qMR (EchoMRI)-measured fat and lean mass, grip strength, rotarod, gait analysis, frailty indexing, and cognition, mirroring those used in prior mouse studies to enable direct cross-species comparison.

The filing reports that in the oldest cohort of super-aged male rats (approximately 24 to 26 months at enrollment), Rotarod distance at Week 16 showed a difference of 90.3 percentage points (p=0.008) between PTC-2105 at 0.5 mg/kg and vehicle. Grip strength at Week 16 increased by +30.7% with PTC-2105 at 0.5 mg/kg versus +7.3% in the vehicle group (difference of +23.4 percentage points; p=0.396; n=3 and n=4, respectively), a result the filing notes was not statistically significant. The company disclosed that results are "preliminary and based on small groups," and that additional cohorts, female rats, and later time points remain ongoing.

The filing also summarizes prior mouse study data, noting that in aged male mice with diet-induced obesity, weight loss with PTC-2105 alone exceeded that with semaglutide after approximately 30 weeks (-9.6% vs. -2.1% from baseline; n=6 vs. 5 surviving mice; p=0.18). Eos SENOLYTIX is planning a randomized, double-blind, placebo-controlled Phase 1b study in participants aged 60 or older with sarcopenia, with a primary endpoint of safety, to begin in 2027, subject to IND application submission and allowance. The filing was made by Pulmatrix, Inc. (NASDAQ:PULM) in connection with a transaction involving Eos SENOLYTIX, Inc., under Commission File No. 333-297342.

What Was Disclosed

Eos SENOLYTIX disclosed early interim results from a second-species aged-rat study of PTC-2105, reporting preserved motor performance and reduced fat mass in super-aged male rats, along with a summary of prior mouse data and plans for IND-enabling toxicology and first-in-human trials.