SOFIE Launches Pivotal Phase 3 Trial for FAPI Cancer Imaging

DULLES, VA – December 29, 2025 – In a significant step forward for oncology and precision medicine, SOFIE Biosciences announced today that the first patient has been dosed in a pivotal Phase 3 clinical trial for its novel radiopharmaceutical, [18F]FAPI-74. The study marks a critical milestone in the development of a new class of diagnostic imaging agents that could fundamentally change how gastrointestinal (GI) cancers are detected and managed.

The first dose was administered at a RadNet facility in Los Angeles, a key partner in the trial alongside Helios Clinical and The Oncology Institute of Hope and Innovation. The event kicks off the FAPI-GO trial, one of two late-stage studies designed to validate the effectiveness of [18F]FAPI-74, a fluorine-18 labeled molecule that targets Fibroblast Activation Protein (FAP), a protein abundant in the environment surrounding tumors.

"We are proud of this milestone in the continuing clinical development of FAPI," said Patrick Phelps, President and CEO of SOFIE Biosciences, in a statement. "FAPI provides a different way to image and identify disease, by targeting cancer-associated fibroblasts in the tumor microenvironment. Dosing the first patient with [18F]FAPI-74 brings us one step closer to addressing vital areas of unmet need in gastric and esophageal cancers and realizing the promise of FAPI PET in precision medicine."

Targeting the Tumor's Support System

For decades, the workhorse of cancer imaging has been the FDG-PET scan, which uses a radioactive glucose analog to detect cells with high metabolic activity. While highly effective, this method has limitations. Some tumors are not highly metabolic, and inflammation can also light up on an FDG scan, leading to potential false positives. The development of FAPI-based imaging represents a paradigm shift, moving the focus from the cancer cells themselves to the complex ecosystem that supports their growth—the tumor microenvironment.

At the heart of this approach is the Fibroblast Activation Protein (FAP). FAP is a protein that is highly expressed on the surface of cancer-associated fibroblasts (CAFs), cells that play a crucial role in creating the structural and biochemical scaffolding for tumors. These fibroblasts are implicated in tumor growth, invasion, and metastasis. In healthy adult tissue, FAP is rarely present, making it an exceptionally clean and specific target for cancer imaging.

[18F]FAPI-74 is a PET tracer designed to bind specifically to FAP. When injected into a patient, it travels through the body and accumulates in areas with high FAP expression. A subsequent PET/CT scan can then generate a detailed, three-dimensional map showing precisely where these cancer-associated fibroblasts are located, effectively illuminating the tumor and any potential metastatic sites. This quinoline-based tracer technology, originally pioneered by researchers at Heidelberg University Hospital in Germany, has shown immense promise in earlier clinical studies across a wide variety of cancers, demonstrating a favorable safety profile and clear, high-contrast images.

The FAPI-GO and FAPI-PRO Trials

To bring this technology to patients, SOFIE has launched two ambitious Phase 3 trials. The first, named FAPI-GO (FAPI in Gastroesophageal Oncology), is now officially underway. This multi-site, open-label study will enroll approximately 200 adults with gastroesophageal cancer across 18 sites over a 24-month period. The primary goal is to assess the sensitivity and specificity of [18F]FAPI-74 PET/CT for detecting distant metastatic disease (M1), which is a critical factor in determining a patient's prognosis and treatment plan. The open-label, non-randomized design means both clinicians and patients will know the agent is being administered, and its performance will be compared against established standards of care for detecting metastases.

Following closely behind is the second Phase 3 study, FAPI-PRO (FAPI in Precision Imaging of Pancreatic Cancer), which began enrollment in December 2025. This trial will apply the same imaging technology to another challenging malignancy: Pancreatic Ductal Adenocarcinoma (PDAC). Like the FAPI-GO trial, FAPI-PRO is a multi-site, open-label study designed to evaluate the utility of [18F]FAPI-74 PET/CT in detecting metastatic disease. Pancreatic cancer is notoriously difficult to diagnose and stage accurately, and a more sensitive imaging tool could have a profound impact on patient outcomes.

Additional details for both the FAPI-GO (NCT07217704) and FAPI-PRO (NCT07217717) trials are publicly available on the ClinicalTrials.gov registry.

A Collaborative Effort in Precision Medicine

The complexity and scale of these trials necessitate a strong network of specialized partners. SOFIE, a developer and manufacturer of radiopharmaceuticals, is leveraging the extensive capabilities of RadNet, a leading national provider of outpatient diagnostic imaging services. RadNet's experience in managing PET/CT clinical trials and its vast network of advanced imaging centers are central to the study's execution.

"FAPI-74 is an exciting new advanced PET tracer," noted Judith Rose, MD, RadNet's Director of PET/CT and Research. "RadNet's experience in PET/CT clinical trials, combined with our national network of advanced imaging capabilities uniquely positions us to support oncology trials to transform cancer diagnosis and treatment. It is an honor to be in the position to have enrolled and imaged, in Los Angeles, the first patient in this important Phase 3 trial."

Clinical operations and patient recruitment are being managed through a partnership with Helios Clinical and The Oncology Institute of Hope and Innovation, a major community-based oncology care provider. This collaboration is designed to embed the clinical trial within real-world care settings, streamlining the process and expanding access for patients who might benefit from this cutting-edge technology.

The Promise of FAPI Beyond Diagnosis

While the immediate goal of the FAPI-GO and FAPI-PRO trials is to validate [18F]FAPI-74 as a superior diagnostic tool, the long-term vision for FAP-targeting agents extends into therapeutics. The high specificity of FAP as a cancer-associated target makes it an ideal candidate for a "theranostic" approach. Theranostics combines diagnosis and therapy by using the same molecular target for both.

In this model, an imaging agent like [18F]FAPI-74 first confirms the presence and location of FAP-expressing tumors. Subsequently, the targeting molecule can be attached to a therapeutic radioisotope instead of a diagnostic one. This therapeutic agent would then travel to the same tumor sites and deliver a payload of cell-killing radiation directly to the cancer microenvironment, minimizing damage to healthy tissue. This dual-purpose strategy represents one of the most exciting frontiers in radiopharmaceutical development, and the successful validation of FAPI imaging is the first essential step toward that future.