Beyond BCG: Breast Milk-Derived Drug Enters US Trials for Resistant Cancer

LUND, Sweden – June 22, 2026 – For thousands of patients diagnosed with high-risk bladder cancer, the standard treatment regimen offers a fighting chance. But for a significant and growing number, that treatment fails, leaving them with a devastating choice: surgically remove the bladder or risk a deadly spread of the disease. Now, a novel therapy derived from an unexpected source—human breast milk—is entering an expanded U.S. clinical trial, offering a potential bladder-sparing lifeline for this exact population.

Swedish biotech firm Hamlet BioPharma has announced a pivotal collaboration with the University of Iowa, a premier American cancer research center, to advance the clinical development of its drug, Alpha1H. The new study will target patients with Carcinoma In Situ (CIS), a severe and notoriously therapy-resistant form of non-muscle-invasive bladder cancer (NMIBC), bringing a promising new weapon to a front line where options have become perilously thin.

The Hidden Cost of a Last Resort

Bladder cancer is one of the world's most common urological malignancies, but its non-muscle-invasive form presents a unique challenge. While the tumors have not yet penetrated the bladder's muscle wall, high-risk variants like CIS are aggressive and prone to recurrence. For decades, the gold standard of care has been intravesical immunotherapy with Bacillus Calmette-Guérin (BCG), a weakened bacterium that stimulates a powerful local immune response to destroy cancer cells.

For many, BCG is effective. But for an estimated 30% to 50% of patients, the treatment eventually stops working, or never works at all. This condition, known as “BCG-unresponsive” disease, puts patients in a precarious position. With the primary defense neutralized, the risk of the cancer progressing to muscle-invasive disease escalates dramatically. At this point, the standard medical recommendation is often a radical cystectomy—the complete surgical removal of the bladder.

This procedure, while life-saving, represents a hidden cost of treatment failure that carries a lifelong burden. Patients require a urinary diversion, fundamentally altering their quality of life. As noted by Dr. Michael O’Donnell, a leading urologic oncologist at the University of Iowa, the unmet need is profound. “Many patients with CIS have exhausted all available treatments, without a cure, and are faced with the prospect of bladder removal,” he stated, highlighting the urgency for new therapeutic avenues.

A Targeted Attack from an Unlikely Source

Into this challenging landscape steps Alpha1H, a drug candidate with a remarkable origin story. It is a synthetic component of a natural complex first discovered in human breast milk called HAMLET (Human Alpha-lactalbumin Made LEthal to Tumor cells). Unlike conventional chemotherapies that cause widespread collateral damage, Alpha1H is engineered for precision. Administered directly into the bladder, the drug selectively enters tumor cells and triggers apoptosis, a form of programmed cell death, effectively compelling the cancer to self-destruct.

Previous clinical studies have shown that this process causes cancerous cells to shed into the urine, providing a real-time, non-invasive biomarker of the drug’s efficacy. The science behind this effect is increasingly clear. Advanced RNA sequencing has revealed that Alpha1H acts like a master switch, turning off more than 700 cancer-related genes, including critical drivers of tumor growth. Furthermore, it activates a local immune response that resembles the effects of BCG, but with a potentially faster onset and a more favorable safety profile, avoiding the persistent and sometimes severe side effects associated with the live bacterial therapy.

This dual mechanism—directly killing tumor cells while simultaneously recruiting the immune system—positions Alpha1H as a uniquely powerful candidate for a disease defined by its resistance to singular approaches.

A Strategic Alliance to Bridge the Atlantic

The new clinical trial is more than just a scientific endeavor; it is a strategic validation of Hamlet BioPharma’s technology on the global stage. The collaboration with the University of Iowa, and specifically with Dr. O’Donnell, a key opinion leader who has pioneered multiple therapies in the field, provides immense credibility. This partnership was initiated after O’Donnell’s team conducted an extensive evaluation of Alpha1H’s mechanism and existing clinical data, concluding that it warranted investigation in this high-need patient group.

This transatlantic alliance is built on a solid regulatory foundation. The new study will be conducted under Hamlet BioPharma’s existing Investigational New Drug (IND) application with the U.S. Food and Drug Administration (FDA). The company had already secured a “Fast Track” designation from the agency in late 2023, a status reserved for drugs that address serious conditions and fill an unmet medical need. This designation facilitates more frequent communication with the FDA and paves the way for a potentially accelerated approval process.

For a Swedish biotech, establishing such a strong clinical footprint in the U.S. with a top-tier academic institution represents a critical step in de-risking development and moving toward the world’s largest pharmaceutical market.

Promising Data Paves the Way for High-Risk Patients

This expansion into treating CIS is not a speculative leap but a calculated step based on compelling prior evidence. Hamlet BioPharma’s earlier Phase 2 study in NMIBC patients demonstrated a strong safety profile and significant anti-tumor effects. In that trial, 80% of patients showed a response to the treatment, with an average tumor size reduction of 59% in the high-dose group. Crucially, no serious drug-related adverse events were reported.

These results provided the confidence to target the more formidable challenge of BCG-unresponsive CIS. “Expanding the clinical indications to include CIS allows us to evaluate Alpha1H in a patient population with severe and resistant disease and a substantial unmet medical need,” said Catharina Svanborg, Chairman of Hamlet BioPharma. The goal is clear: to offer an effective, bladder-preserving therapy where none currently exists.

While the journey from an expanded clinical trial to a widely available therapy remains long and rigorous, this collaboration marks a significant inflection point. For patients staring down the life-altering prospect of a radical cystectomy, the targeted science of Alpha1H represents a tangible source of new hope.