LeonaBio reports first quarter 2026 results and ELAINE-3 amendment

LeonaBio, Inc. (NASDAQ: LONA) reported financial results for the quarter ended March 31, 2026 in a release dated May 7, and provided a business update. The company said it is advancing lasofoxifene in its Phase 3 ELAINE-3 trial and is on track to start a Phase 2 proof-of-concept study of ATH-1105 in patients with amyotrophic lateral sclerosis (ALS) in the second half of 2026. The release lists three board appointments among recent events.

ELAINE-3 and the amendment

The release describes lasofoxifene as a novel, nonsteroidal selective estrogen receptor modulator designed to act against wild-type and mutant breast estrogen receptors while preserving estrogen signaling in tissues such as bone. LeonaBio acquired an exclusive global license to develop and commercialize the drug from Sermonix Pharmaceuticals, Inc. in December 2025, excluding Asia and certain countries in the Middle East.

The company is amending the ELAINE-3 protocol to increase the sample size from 500 participants to up to 600 participants. The primary goal of the amendment is to help ensure the trial reaches the appropriate number of disease progression events. The company expects to complete enrollment in the fourth quarter of 2026 and to have topline data in the second half of 2027. The trial is testing lasofoxifene with abemaciclib in estrogen receptor-positive, HER2-negative, ESR1-mutated metastatic breast cancer that has progressed on aromatase inhibitors and CDK4/6 inhibitors.

The release also reports nonclinical data presented at AACR26 by independent researchers at Virginia Commonwealth University's Massey Comprehensive Cancer Center on lasofoxifene and its potential bone protective role in metastatic breast cancer. The release says the lasofoxifene studied came from an independent source for research use only.

The release also recaps two earlier Phase 2 studies. In ELAINE-1, median progression-free survival was 5.6 months for lasofoxifene against 3.7 months for fulvestrant, and the objective response rate was 13.3% against 2.9%. In ELAINE-2, a study of lasofoxifene with abemaciclib, median progression-free survival was approximately 13 months and the objective response rate was 56%.

ATH-1105 and the board

ATH-1105 is described as a novel, orally available, brain-penetrant small molecule designed to positively modulate the neurotrophic HGF system, with potential use in ALS, Alzheimer's disease and Parkinson's disease. The company presented Phase 1 results at the ALS Nexus 2025 conference in August 2025. The Phase 1 trial enrolled 80 healthy volunteers in a double-blind, placebo-controlled study that was completed in November 2024. The release says it showed a favorable safety and tolerability profile, dose-proportional pharmacokinetics and CNS penetration.

LeonaBio appointed Fred Callori, J.D., Natalie Holles and Peter B. Silverman, J.D. to its board of directors, effective May 5, 2026. John Fluke, Jr., who had served on the board since 2014, retired effective May 4, 2026.

Financial position

The annual report figures in SEC XBRL data show research and development expense of $17.5 million for 2025, compared with $70.7 million for 2024. The net loss was $105.6 million for 2025 and $96.9 million for 2024. Operations used $45.7 million of cash in 2025 and $97.2 million in 2024. At year-end 2024, the company reported cash and cash equivalents of $48.4 million and short-term investments of $2.8 million.

The release refers to a December 2025 financing of $90 million in common stock and warrants. It says the cash-exercisable warrants could bring up to an additional $146 million if exercised.

What the data do not show

The efficacy numbers come from earlier studies, not ELAINE-3. ELAINE-1 was open-label and, in the release's own words, not powered, and the release gives no p-values for its comparison with fulvestrant. ELAINE-2 was open-label and enrolled heavily pretreated patients, and the release quotes its results without a control arm. The AACR26 work was nonclinical and used lasofoxifene unrelated to LeonaBio's investigational product. Topline data are not expected until the second half of 2027.

ATH-1105 has only Phase 1 data from 80 healthy volunteers, with no efficacy reported in ALS. The latest annual figures show a net loss of $105.6 million in 2025, with operations using $45.7 million of cash. The cash-exercisable warrants could bring up to $146 million only if holders exercise them, and exercise would add shares.

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