Aptone Begins U.S. Phase 3 Trial of FDA Orphan Drug GPC-100... "Aiming for Rapid Approval with Single 120-Patient Study"

Aptone, a subsidiary of Aprogen, is accelerating its efforts to conduct a Phase 3 clinical trial and pursue a New Drug Application (NDA) in the United States for its hematopoietic stem cell mobilizer 'Burixafor (GPC-100),' which has received orphan drug designation from the U.S. Food and Drug Administration (FDA). The company plans to shorten the development timeline and nurture the drug as a global blockbuster by leveraging precedents in which marketing approval was obtained through a single Phase 3 trial with a relatively small patient cohort.

On August 31, Aptone announced that it had finalized the Phase 3 protocol with the FDA based on the results of the U.S. Phase 2 trial for GPC-100, for which it recently secured global exclusive rights. The company stated it will soon begin the late-stage clinical study.

GPC-100 is a mobilizer that rapidly moves hematopoietic stem cells and immune cells into the peripheral blood in patients with blood cancers, including multiple myeloma. It works by binding to a complex of the CXCR4 and ADRB2 cell membrane proteins and has also been granted orphan drug designation by the FDA.

Aptone is focusing on the scalability of its clinical development. Motixafortide (brand name: Aphexda), another drug in the CXCR4 class, received FDA approval in September 2023 after a single Phase 3 trial involving 122 patients. Based on this precedent, Aptone aims to progress GPC-100 development with a single Phase 3 trial involving around 120 patients, rather than conducting a large-scale study, with the goal of obtaining clinical results within two years.

The company also expects to benefit from the advantages of orphan drug designation. By utilizing the FDA's Fast Track program, GPC-100 may qualify for expedited review and, after its launch in the United States, could secure seven years of orphan drug exclusivity independently of patent protection.

One of GPC-100’s distinguishing features is its rapid onset of action. While existing mobilizers typically take 10 to 14 hours to show effect, GPC-100 was observed to significantly increase hematopoietic stem cells and immune cells within one hour of administration in the U.S. Phase 2 study, according to the company.

The company believes that the expansion of the multiple myeloma treatment market will drive potential demand for GPC-100. Darzalex (active ingredient: daratumumab), which is widely used to treat multiple myeloma, binds not only to blood cancer cells but also to hematopoietic stem cells and white blood cells, potentially inhibiting the movement of these cells and thus necessitating the use of a stem cell mobilizer.

The global market for Darzalex is also growing rapidly. According to the company, the Darzalex market size reached $9.744 billion (about KRW 13 trillion) in 2025. GPC-100 also has the potential to expand its indications beyond multiple myeloma to acute myeloid leukemia (AML) and sickle cell disease (SCD).

The commercial value of the drug has already been validated through similar licensing deals. After receiving approval in 2023, Motixafortide transferred its rights for the Asian region to Guangzhou Gloria Biosciences in China and its rights for other regions to AerMed in Ireland. The combined upfront payment for both agreements amounted to $358 million (about KRW 500 billion), and included royalties of up to 23% of net sales.

Aptone plans to expand the application of GPC-100 into the cell and gene therapy field. In particular, the company sees potential to leverage GPC-100’s ability to rapidly amplify immune cells in 'in vivo CAR-T' therapies, which involve converting patients’ T cells into CAR-T cells within the body.

An Aptone official stated, "Unlike existing mobilizers, GPC-100 was confirmed to act within an hour in the U.S. Phase 2 trial. Leveraging the prospect of rapid FDA approval and expanded indications, we will develop GPC-100 as a key new drug asset to significantly enhance the company’s value."

This content was produced with the assistance of AI translation services.