LOUISVILLE, Kentucky, and MENLO PARK, California, October 27, 2026
US WorldMeds Ventures, LLC has acquired Orbus Therapeutics, Inc., through a definitive merger agreement, expanding its commitment to rare diseases and strengthening its oncology development portfolio. The acquisition brings Orbus’ late-stage investigational eflornithine (DFMO) programme for recurrent Grade 3 astrocytoma into the US WorldMeds portfolio. The transaction represents an important development in the company’s strategy to advance treatments for patients affected by serious and underserved diseases, particularly rare brain tumours. Under the agreement, US WorldMeds made an undisclosed upfront payment to Orbus, which is also eligible to receive additional development, regulatory and sales-based milestone payments, together with tiered royalties on net U.S. sales. Following the completion of the acquisition, Orbus Therapeutics will operate as a wholly owned subsidiary of US WorldMeds.
US WorldMeds Expands Rare Disease and Oncology Portfolio
The acquisition strengthens US WorldMeds’ presence in rare-disease therapeutics by adding Orbus’ clinical-stage eflornithine programme for adult malignant glioma. US WorldMeds already commercializes IWILFIN® (eflornithine 192 mg tablets) for a separate rare oncology indication involving high-risk neuroblastoma. The company intends to leverage its existing development, regulatory and commercialization capabilities to evaluate the next steps for eflornithine in recurrent Grade 3 astrocytoma. The acquisition also provides an opportunity to explore additional potential applications in adult malignant glioma. According to the companies, the transaction builds on the scientific and clinical foundation established by Orbus through its Phase 3 STELLAR study. US WorldMeds leadership highlighted the importance of advancing medicines for underserved patient populations and evaluating the clinical potential of treatments that may address significant unmet medical needs. The financial terms also include potential future payments linked to development progress, regulatory milestones and commercial performance.
Phase 3 STELLAR Study Reports Survival Improvements
A key scientific foundation for the acquisition is the Phase 3 STELLAR clinical trial, which evaluated oral eflornithine in combination with lomustine compared with lomustine alone in 343 patients with recurrent Grade 3 astrocytoma under the 2016 World Health Organization (WHO) classification. Although the study did not demonstrate an overall survival difference between the treatment groups in the overall intent-to-treat population, a prespecified subgroup analysis evaluated patients classified as having IDH-mutant Grade 3 astrocytoma under the updated 2021 WHO classification. This subgroup included 196 patients and demonstrated clinically meaningful improvements in overall survival and progression-free survival with the combination treatment. Median overall survival reached 34.9 months with eflornithine plus lomustine, compared with 23.5 months with lomustine alone. The analysis also showed that median progression-free survival, based on investigator assessment, more than doubled, reaching 15.8 months compared with 7.2 months for lomustine alone. The reported hazard ratios were 0.64 for overall survival and 0.57 for progression-free survival. No benefit was observed in patients with Grade 4 tumours under the updated classification. These findings were subsequently published in the Journal of Clinical Oncology in 2026, providing peer-reviewed evidence for the reported subgroup outcomes.
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Eflornithine Targets Cancer Cell Growth Pathways
Eflornithine, also known as DFMO, is an oral investigational medicine that irreversibly inhibits ornithine decarboxylase (ODC), an enzyme involved in polyamine synthesis. Polyamines are essential molecules that support cellular growth and proliferation. Certain cancer cells, including glioma cells, depend on elevated polyamine levels to sustain their growth, making ODC an important therapeutic target under investigation. By inhibiting this enzyme, eflornithine is designed to interfere with a biological pathway associated with tumour cell proliferation. The STELLAR study evaluated an oral eflornithine solution developed by Orbus in combination with lomustine, an established chemotherapy agent. The reported safety findings included Grade 3 or higher treatment-emergent adverse events, particularly myelosuppression and hearing impairment. Myelosuppression occurred in 42% of patients receiving the combination compared with 29% receiving lomustine alone, while hearing impairment was reported in 24% compared with 0%, respectively. These findings highlight the importance of continued safety assessment during further clinical and regulatory development.
Following the acquisition, US WorldMeds plans to evaluate the development and regulatory pathway for eflornithine in recurrent IDH-mutant Grade 3 astrocytoma and other potential adult malignant glioma indications. The company also expects to engage with the U.S. Food and Drug Administration (FDA) regarding the most appropriate next steps for the programme. Eflornithine remains investigational for glioma treatment and is not FDA-approved for this indication. Its safety and efficacy for treating glioma have not been established. The acquisition nevertheless represents a strategic expansion of US WorldMeds’ rare-oncology activities and creates an opportunity to further investigate a potential treatment approach for patients with recurrent malignant brain tumours.
Source: US WorldMeds, Orbus Therapeutics press release
