By Gabriel Paijo 
Triple-negative breast cancer (TNBC) remains one of the most formidable challenges in modern oncology, characterized by its aggressive growth, high rate of early metastasis, and a systemic lack of the three most common receptors—estrogen, progesterone, and HER2—that typically serve as targets for hormone-based or HER2-directed therapies. For decades, the primary recourse for patients diagnosed with TNBC has been a combination of surgery, radiation, and cytotoxic chemotherapy. While many patients initially see a reduction in tumor size, the disease is notorious for its ability to develop resistance, leading to recurrences that are significantly more difficult to treat. However, a landmark study published in the journal Breast Cancer Research by a multidisciplinary team at the MUSC Hollings Cancer Center has unveiled a potential paradigm shift in the treatment of this lethal malignancy.
The research centers on the development of an experimental, humanized monoclonal antibody designed to inhibit a specific protein known as secreted frizzled-related protein 2 (SFRP2). This protein has been identified as a master regulator that tumors exploit to ensure their survival, facilitate their spread, and evade the body’s natural immune defenses. In preclinical models, the antibody not only slowed the progression of primary tumors but also dramatically reduced the incidence of lung metastasis—a common and often fatal complication of TNBC. Perhaps most significantly, the therapy demonstrated an ability to revive exhausted immune cells and kill cancer cells that had already become resistant to conventional chemotherapy drugs like doxorubicin.
The Evolution of SFRP2 Research: A Two-Decade Journey
The discovery of the SFRP2 antibody is the culmination of nearly 20 years of rigorous scientific inquiry led by Nancy Klauber-DeMore, M.D., a renowned breast surgical oncologist and co-leader of the Developmental Cancer Therapeutics Research Program at Hollings Cancer Center. The journey began in 2008 when Dr. Klauber-DeMore’s laboratory first identified SFRP2 as a key driver in breast cancer progression. Over the subsequent decade and a half, the research team—which included experts from MUSC’s departments of Surgery, Biochemistry and Molecular Biology, and Pathology and Laboratory Medicine—worked to decode the exact mechanisms through which this protein operates.
SFRP2 is a multifaceted enabler of malignancy. It promotes angiogenesis, the process by which tumors grow new blood vessels to supply themselves with nutrients and oxygen. It also acts as an anti-apoptotic factor, essentially preventing cancer cells from undergoing programmed cell death even when damaged by therapy. Furthermore, the protein plays a sinister role in the tumor microenvironment by "exhausting" immune cells, rendering them incapable of attacking the cancer. By developing a humanized monoclonal antibody specifically engineered to bind to SFRP2, the MUSC team has created a tool that can theoretically dismantle these survival strategies simultaneously.
Reprogramming the Tumor Microenvironment
One of the most innovative aspects of the study is its focus on the "immune microenvironment"—the ecosystem of cells surrounding a tumor. Traditionally, cancer treatment has focused almost exclusively on killing the cancer cells themselves. However, modern oncology increasingly recognizes that the surrounding environment, particularly immune cells known as macrophages, can either hinder or help a tumor’s growth.
Macrophages are generally categorized into two functional states: M1 and M2. M1 macrophages are "pro-inflammatory" and help the immune system identify and destroy cancer cells. Conversely, M2 macrophages are "anti-inflammatory" and are often co-opted by tumors to suppress the immune response and promote tissue repair, which inadvertently helps the cancer thrive. In the case of TNBC, the tumor microenvironment is typically dominated by M2 macrophages, creating an "immune desert" where the body’s natural defenses are silenced.
The MUSC research, which included contributions from surgical residents Lillian Hsu, M.D., and Julie Siegel, M.D., revealed that SFRP2 is expressed not just on the cancer cells, but also on these tumor-associated macrophages. This was a groundbreaking revelation. By administering the SFRP2 antibody, the researchers observed a dramatic shift in the macrophage population. The treatment triggered the release of interferon-gamma, a potent immune signaling molecule, which effectively "reprogrammed" the M2 macrophages back into the cancer-fighting M1 state.
"We discovered that it pushes macrophages toward the ‘good’ M1 state—without the toxic effects you’d see if you gave interferon-gamma directly," noted Dr. Hsu. This localized activation is a critical distinction, as systemic administration of interferon-gamma often leads to severe side effects that limit its clinical utility. By inducing its production specifically within the tumor site, the antibody achieves a therapeutic effect while maintaining a high safety profile.
Strengthening the T-Cell Response and Reducing Metastasis
The impact of the SFRP2 antibody extends beyond macrophages to include T-cells, the primary "soldiers" of the adaptive immune system. In many advanced cancers, T-cells become "exhausted" due to chronic exposure to tumor antigens and inhibitory signals within the microenvironment. These exhausted T-cells lose their ability to proliferate and kill cancer cells. The MUSC study found that the SFRP2 antibody restored the activity of these tumor-infiltrating lymphocytes, suggesting that the therapy could work synergistically with existing immunotherapies, such as checkpoint inhibitors, which often fail in TNBC patients because their T-cells are too depleted to respond.
The precision of the antibody was further demonstrated through imaging and distribution studies. When the antibody was introduced into the body, it selectively accumulated within tumor tissues rather than healthy organs. This level of specificity is the hallmark of precision medicine, contrasting sharply with traditional chemotherapy, which circulates through the entire body and damages healthy rapidly-dividing cells in the bone marrow, gut, and hair follicles.
This precision likely contributes to the antibody’s success in preventing metastasis. In two distinct models of advanced TNBC, mice treated with the antibody showed significantly fewer secondary tumors in the lungs. Since lung metastasis is a leading cause of mortality in breast cancer, the ability to contain the disease within the primary site or eliminate circulating tumor cells represents a major clinical milestone.
Overcoming the Hurdle of Chemotherapy Resistance
Perhaps the most encouraging finding for patients with recurrent disease is the antibody’s efficacy against chemotherapy-resistant cells. Resistance to doxorubicin, a cornerstone of TNBC treatment, is a frequent and devastating occurrence. The research team specifically tested the SFRP2 antibody on cancer cell lines that had been engineered to survive high doses of doxorubicin. Remarkably, the antibody remained highly effective at inducing cell death in these resistant populations.
This suggests that SFRP2-targeted therapy does not rely on the same pathways as traditional cytotoxic drugs. By targeting the survival infrastructure of the tumor rather than just its DNA replication process, the antibody offers a secondary line of defense for patients who have exhausted standard-of-care options. "That’s a very encouraging finding," Dr. Klauber-DeMore stated, "because it suggests the therapy may be effective even when standard treatments fail."
Path to Clinical Trials and Regulatory Status
The promising preclinical data has already paved the way for the next phase of development. The antibody has been licensed to Innova Therapeutics, a biotechnology company based in Charleston, South Carolina. Co-founded by Dr. Klauber-DeMore, the company is currently focused on securing the necessary funding and regulatory approvals to initiate a Phase I clinical trial, which would mark the first time the therapy is tested in humans.
The potential of SFRP2-targeted therapy has also caught the attention of the U.S. Food and Drug Administration (FDA). The agency has granted the antibody both Rare Pediatric Disease and Orphan Disease designations for the treatment of osteosarcoma, a type of bone cancer that also heavily expresses the SFRP2 protein. While these designations do not constitute an approval for general use, they provide significant financial and regulatory incentives to accelerate the drug’s development. This cross-application to other types of cancer underscores the fundamental role SFRP2 plays in various aggressive malignancies.
Broader Implications for Oncology
The implications of this research extend far beyond TNBC. The discovery that a single protein links tumor growth, immune evasion, and drug resistance provides a new "master key" for therapeutic intervention. If the clinical trials prove successful, this antibody could represent a new class of "microenvironment-normalizing" therapies. Rather than just attacking the tumor, these drugs would "re-engineer" the body’s own internal landscape to be hostile to cancer.
Furthermore, the study highlights the importance of long-term, multidisciplinary research in the academic setting. Dr. Klauber-DeMore’s 20-year commitment to studying SFRP2 illustrates how foundational biological discoveries can eventually translate into life-saving clinical tools. As the medical community moves toward more personalized and less toxic treatment regimens, the SFRP2 antibody stands as a testament to the power of targeted immunotherapy.
While the transition from mouse models to human patients is always a complex and uncertain process, the depth of the data provided by the MUSC Hollings Cancer Center team offers a robust foundation. For patients facing the daunting diagnosis of triple-negative breast cancer, the prospect of a treatment that can bypass chemotherapy resistance and mobilize the immune system offers a significant beacon of hope in a field where options have historically been limited. The upcoming years will be critical as researchers move from the laboratory bench to the patient’s bedside, potentially transforming TNBC from a feared diagnosis into a manageable, or even curable, condition.
