LeonaBio On Track to Complete Phase 3 ELAINE-3 Enrollment for Lasofoxifene in ESR1-Mutated Metastatic Breast Cancer in 4Q 2026
核心洞察
LeonaBio (搜索) has enrolled 495 patients and remains on track to complete enrollment of the Phase 3 ELAINE-3 trial of lasofoxifene in 4Q 2026, with topline data expected in 2H 2027.
ELAINE-3 evaluates lasofoxifene combined with abemaciclib in ER+, HER2-negative, ESR1 (搜索)-mutated metastatic breast cancer (搜索), with progression-free survival as the primary endpoint.
Prior Phase 2 data showed a median PFS of approximately 13 months and a 56% objective response rate for the lasofoxifene-abemaciclib combination in heavily pretreated patients.
LeonaBio (搜索), Inc. (NASDAQ: LONA), a clinical-stage biopharmaceutical company, reported its second quarter 2026 financial results and provided a business update, announcing that it has enrolled 495 patients and remains on track to complete enrollment of its Phase 3 ELAINE-3 clinical trial of lasofoxifene in the fourth quarter of 2026, with topline data expected in the second half of 2027.
"We enter the second half of 2026 with a clear focus on executing our Phase 3 ELAINE-3 trial and advancing lasofoxifene toward what we believe could be a transformative treatment option for patients with ESR1 (搜索)-mutated metastatic breast cancer (搜索)," said Mark Litton, Ph.D., President and Chief Executive Officer of LeonaBio (搜索). "We have enrolled 495 patients and remain on track to complete enrollment of ELAINE-3 in the fourth quarter of 2026 with topline data expected in the second half of 2027."
Lasofoxifene and the ELAINE-3 Registrational Trial
Lasofoxifene is a third-generation, novel, nonsteroidal selective estrogen receptor modulator (SERM) with a unique binding profile, designed to confer potent activity against both wild-type and mutant estrogen receptors, including the clinically significant ESR1 (搜索) mutations commonly associated with resistance to endocrine therapy in metastatic breast cancer (搜索).
The drug is being advanced in ELAINE-3, a Phase 3 clinical trial (NCT05696626), in combination with abemaciclib, a CDK4/6 (搜索) inhibitor, as a targeted therapy for estrogen receptor-positive (ER+), HER2-negative, ESR1 (搜索)-mutated metastatic breast cancer (搜索), following progression on aromatase inhibitors and CDK4/6 inhibitors. The primary endpoint of the study is a statistically significant improvement in progression-free survival (PFS), as determined by blinded, independent central review (BICR). ELAINE-3 aims to establish a new standard of care for this genetically defined patient group with limited treatment options.
The Company expects to complete enrollment of approximately 600 participants in the Phase 3 ELAINE-3 clinical trial in the fourth quarter of 2026 and to have topline data in the second half of 2027.
Prior Phase 2 Evidence
Lasofoxifene was previously evaluated in two Phase 2 studies in patients with ER+, HER2-negative locally advanced or metastatic breast cancer (搜索) expressing an ESR1 (搜索) mutation, ELAINE-1 and ELAINE-2.
ELAINE-1, an open-label, randomized trial comparing lasofoxifene to fulvestrant, showed improved outcomes for lasofoxifene as a potential monotherapy. Although the trial was not powered, results included longer median progression-free survival (5.6 vs. 3.7 months), higher objective response rates (13.3% vs. 2.9%), and a durable complete response lasting more than 2.5 years. The treatment was well-tolerated with patients reporting quality-of-life benefits.
ELAINE-2, an open-label study evaluating lasofoxifene in combination with abemaciclib, demonstrated clinical benefits in heavily pretreated patients, with a median progression-free survival of approximately 13 months, an objective response rate of 56%, and a clinical benefit rate of 65.5%. The combination was generally well-tolerated with most adverse events being low grade.
Licensing and Pipeline
In December 2025, LeonaBio (搜索) acquired an exclusive global license (excluding Asia and certain countries in the Middle East) from Sermonix Pharmaceuticals (搜索), Inc. for rights to develop and commercialize lasofoxifene.
Beyond lasofoxifene, LeonaBio (搜索) is advancing brelgometon (搜索) (ATH-1105), a novel, orally available, brain-penetrant, next-generation small molecule drug candidate designed to positively modulate the neurotrophic HGF system for potential treatment of neurodegenerative diseases, including amyotrophic lateral sclerosis (搜索) (ALS), Alzheimer's disease, and Parkinson's disease. Brelgometon is currently in clinical development for the potential treatment of ALS. LeonaBio's first-in-human Phase 1 double-blind, placebo-controlled clinical trial (NCT06432647) enrolled 80 healthy volunteers to evaluate single and multiple oral ascending doses of brelgometon, demonstrating a favorable safety and tolerability profile as well as dose-proportional pharmacokinetics and CNS penetration.
Financial Position
Cash, cash equivalents and investments were $51.1 million as of June 30, 2026, compared to $88.3 million as of December 31, 2025. Net cash used in operations was $37.9 million for the quarter ended June 30, 2026, compared to $21.7 million for the quarter ended June 30, 2025.
In conjunction with the December 2025 Sermonix license agreement, LeonaBio (搜索) announced a $90 million private placement financing of common stock and warrants, with the Series A warrants providing, if exercised in full, up to an additional $146 million to support development through key clinical and regulatory milestones.
Research and development expenses were $12.9 million for the quarter ended June 30, 2026, compared to $3.7 million for the quarter ended June 30, 2025, an increase driven primarily by clinical trial spend related to the ELAINE-3 trial for lasofoxifene. Net loss was $19.0 million, or $0.80 per share, for the quarter ended June 30, 2026, compared to a net loss of $7.0 million, or $1.78 per share, for the quarter ended June 30, 2025.
"As we approach the completion of enrollment in this Phase 3 registrational trial, we are investing today in critical CMC, regulatory, and commercial readiness activities to ensure we are well-positioned to bring this therapy to patients as quickly as possible, if approved," added Dr. Litton.