Exicure completes Phase 2 trial of GPC-100 for stem cell mobilization in multiple myeloma patients

Clinical-stage biotech company Exicure, Inc. (NASDAQ: XCUR) has achieved a key development milestone by completing the final patient visit in its ongoing Phase 2 trial of GPC-100 (burixafor), in combination with propranolol and G-CSF, for hematopoietic stem cell mobilization in patients with multiple myeloma undergoing autologous stem cell transplant (ASCT). The Redwood City-based company expects topline results from the randomized, open-label, multicenter trial in the fourth quarter of 2025, setting the stage for pivotal development and potential strategic expansion of its hematology platform.

The announcement comes as investor and clinical attention intensifies around hematopoietic stem cell mobilization innovations, a segment traditionally dominated by agents such as plerixafor and filgrastim. Exicure’s GPC-100 is a novel CXCR4 antagonist designed to address unmet needs in the stem cell mobilization process, which remains logistically complex and physiologically taxing for older or frail multiple myeloma patients—a key consideration in transplant-eligible populations.

What is GPC-100 and how does it aim to improve stem cell mobilization?

GPC-100 is a small molecule antagonist of the CXCR4 receptor, a well-known regulator of hematopoietic stem cell retention within the bone marrow niche. By antagonizing CXCR4, GPC-100 disrupts the stromal cell-derived factor-1 (SDF-1) signaling pathway, facilitating the migration of CD34+ hematopoietic stem cells into peripheral blood, where they can be harvested for autologous transplantation.

In Exicure’s Phase 2 trial (NCT05561751), GPC-100 was combined with propranolol and granulocyte colony-stimulating factor (G-CSF), aiming to enhance mobilization potency while simplifying the timing of administration. At the 2024 American Society of Hematology (ASH) meeting, preliminary data showed that GPC-100 mobilized stem cells with speed and efficacy comparable or superior to existing regimens, enabling a potential same-day collection process.

According to Dr. Muthalagu Ramanathan, Director of the Myeloma Program at U Mass Memorial Health, the rapid pharmacodynamic profile of GPC-100 significantly streamlines the patient experience. “GPC-100 needed to be administered just 45 minutes before stem cell collection and resulted in a successful mobilization, significantly improving the patient experience. This is a true blessing for our frail myeloma patients,” said Dr. Ramanathan in a statement shared by the company.

How does Exicure’s strategy align with stem cell transplant and gene therapy trends?

The development of GPC-100 reflects a broader industry trend toward optimizing conditioning and mobilization regimens to improve safety, timing, and patient convenience—especially in autologous transplant settings where chemotherapy-free mobilization is an emerging goal. Cell and gene therapy platforms also depend heavily on efficient collection of stem cells, and a fast-acting, well-tolerated mobilization agent like GPC-100 could have implications beyond multiple myeloma.

Exicure has indicated interest in leveraging GPC-100’s mechanism in other hematologic indications, including an upcoming Phase 1 trial in acute myeloid leukemia (AML). Moreover, the company has disclosed ongoing discussions for collaboration opportunities targeting the cell and gene therapy space—suggesting potential utility in ex vivo manufacturing processes where rapid mobilization of healthy donor stem cells is critical.

This pivot toward cell and gene therapy applications could position Exicure alongside players like Magenta Therapeutics, bluebird bio, and Rocket Pharmaceuticals, all of whom have explored novel mobilization and collection techniques for stem and progenitor cells used in engineered cell therapies.

What are the clinical trial design and upcoming milestones?

The Phase 2 study enrolled multiple myeloma patients eligible for ASCT and assessed the safety, tolerability, and efficacy of GPC-100 plus propranolol and G-CSF in mobilizing CD34+ cells. The study featured a randomized, open-label, multicenter design and was conducted at leading transplant centers across the U.S.

The primary endpoint focuses on the proportion of patients achieving successful stem cell collection (defined as >2 × 10⁶ CD34+ cells/kg) with minimal leukapheresis sessions. Secondary measures include total CD34+ yield, number of apheresis days, adverse events, and transplant engraftment outcomes.

With the last patient visit now completed, data cleaning, database lock, and statistical analyses are underway. Topline results are slated for release in Q4 2025, and if positive, may catalyze pivotal trial planning or fast-track discussions with the U.S. Food and Drug Administration (FDA).

How has the market responded to Exicure’s development progress?

While Exicure’s stock (NASDAQ: XCUR) has traded with volatility typical of early-stage biotech firms, the company’s continued progress in its clinical programs has drawn cautious optimism from niche investors. Its focus on a differentiated small molecule asset in a highly specific transplant mobilization niche may provide a clearer regulatory and commercial pathway than broader oncology therapeutics.

Institutional sentiment appears to be in a holding pattern as investors await data from the now-completed trial. The near-term share movement may depend on emerging preclinical partnership announcements or further updates around the AML and gene therapy use cases of GPC-100.

The company previously announced a strategic refocus from neuroscience to hematology and stem cell medicine in late 2023, which followed a period of cost-cutting and restructuring aimed at preserving cash runway. That move was generally viewed favorably by analysts tracking asset prioritization in small-cap biotech.

What comes next for Exicure’s hematology pipeline and business model?

With the Phase 2 study now complete, Exicure’s immediate priorities are threefold: deliver strong topline data from the multiple myeloma cohort, secure a clinical site footprint for the upcoming AML study, and formalize one or more industry collaborations that could validate GPC-100’s platform potential.

In parallel, the company is believed to be exploring non-dilutive financing options to sustain pipeline momentum, particularly if external partnerships materialize. Analysts expect any collaborations involving GPC-100 in gene therapy or donor mobilization to be milestone-structured, helping extend Exicure’s financial runway.

If GPC-100 secures regulatory traction, it could enter a global stem cell mobilization market projected to reach $875 million by 2030, according to analysts tracking hematologic transplant trends. The agent’s differentiated speed and patient-friendly administration profile could grant it competitive advantage over longer-acting or more cumbersome mobilization regimens.

Exicure’s repositioning strategy, supported by GPC-100’s data cadence and potential cross-sector utility, is viewed as a targeted bet on the convergence of stem cell transplantation and next-generation ex vivo therapies—a sector that continues to attract licensing interest, particularly from gene therapy developers in Europe, Japan, and North America.