Purple Biotech Secures Key Patent for Next-Gen Cancer Immunotherapy Platform

REHOVOT, Israel – September 02, 2026 – In a significant move that strengthens its competitive footing in the oncology space, clinical-stage company Purple Biotech Ltd. announced it has received a Notice of Allowance from the U.S. Patent and Trademark Office (USPTO). The notice covers key aspects of its CAPTN-3 platform, a technology designed to create a new generation of highly targeted, multi-specific antibodies to fight cancer.

This development provides a critical layer of intellectual property protection for the company’s modular approach to immunotherapy, potentially accelerating the development of novel treatments and enhancing its appeal for future strategic partnerships. For a clinical-stage company, where innovation is the primary currency, securing robust patent protection is a foundational milestone that can dictate its trajectory for years to come.

Decoding CAPTN-3's Modular Advantage

At the heart of the announcement is Purple Biotech's CAPTN-3 platform, an engine for creating conditionally activated, tri-specific antibodies. While the terminology is complex, the underlying concept represents a sophisticated attempt to solve two of the most persistent challenges in cancer therapy: treatment efficacy and patient safety.

Modern immunotherapy has been revolutionized by antibodies that can target cancer cells or modulate the immune system. Multispecific antibodies take this a step further by engaging two or more targets simultaneously. Purple Biotech’s platform advances this concept into tri-specific territory, but with several key innovations outlined in the newly allowed patent:

• Tri-Specific Targeting with Dual TAA Binders: CAPTN-3 antibodies are engineered to bind to three distinct targets. Crucially, this includes two different tumor-associated antigens (TAAs) on the cancer cell's surface, plus an activating receptor on an immune cell (like a T-cell or NK cell). Targeting two separate TAAs dramatically increases the antibody's specificity for cancer cells, reducing the risk of it attacking healthy tissue. This dual-lock system also provides a powerful strategy to overcome tumor heterogeneity, where cancer cells within the same tumor express different markers, a common reason for treatment failure.

• Conditional Activation: Perhaps the platform's most compelling feature is its “masking” or “capping” technology. The antibodies are designed to remain largely inert in the bloodstream and only become fully active within the unique biochemical environment of a tumor. This aims to confine the potent, immune-stimulating, and cancer-killing activity directly to the tumor site, thereby minimizing systemic side effects like cytokine release syndrome (CRS), a dangerous inflammatory response that has plagued many powerful immunotherapies.

• A Modular, 'Plug-and-Play' Architecture: The patent reinforces protection for the platform’s modular design. This allows scientists to efficiently swap out different TAA-binding domains while retaining the core antibody backbone and conditional activation mechanism. This 'plug-and-play' capability transforms the platform from a single-drug project into a rapid-development engine, enabling Purple Biotech to quickly generate new therapeutic candidates for a wide array of cancer indications.

Intellectual Property as a Strategic Cornerstone

For investors and potential partners, the distinction between a 'Notice of Allowance' and a fully issued patent is important. This notice signifies that the USPTO's patent examiners have completed their substantive review and have determined that the invention meets the stringent requirements for patentability—namely, that it is novel, useful, and non-obvious. While Purple Biotech must still pay the required issue fees before the patent is formally granted, this notice is the final and most significant hurdle in the prosecution process, making the grant of the patent highly probable.

This intellectual property fortress is more than just a legal shield; it is a critical business asset. In the high-stakes world of biopharmaceutical development, a strong patent estate is fundamental to a company's valuation and long-term strategy. It provides market exclusivity, preventing competitors from replicating the proprietary technology for the life of the patent, and secures the potential for future revenue streams from any successful drug candidates.

Gil Efron, CEO of Purple Biotech, underscored this strategic value in a statement. "This U.S. patent allowance is another important element in the evolution of the CAPTN-3 platform," he said. "Beyond expanding our intellectual property portfolio, it reinforces protection for the modular design that allows us to rapidly develop new multispecific antibody candidates." Efron’s emphasis on the platform's versatility and its "future development and partnering potential" signals a clear strategy: leveraging this strengthened IP position to attract the deep-pocketed pharmaceutical giants needed to bring these complex therapies through costly late-stage trials and to market.

Navigating a Crowded and Promising Field

The development of multispecific antibodies is one of the most dynamic and competitive areas in oncology. Pioneers like Amgen, with its BiTE (Bispecific T-cell Engager) platform, and major players such as Genmab, Roche, and Johnson & Johnson have already demonstrated the profound clinical impact of these therapies, particularly in treating hematological malignancies. Approved drugs like Blincyto and Tecvayli have offered new hope to patients with difficult-to-treat blood cancers.

However, the field is still grappling with significant challenges that next-generation platforms like CAPTN-3 aim to address. The severe toxicity associated with first-generation T-cell engagers remains a primary concern, often requiring intensive patient monitoring and hospitalization. Furthermore, translating the success seen in blood cancers to solid tumors has proven far more difficult, hindered by the complex and immunosuppressive tumor microenvironment that prevents immune cells from infiltrating and attacking the cancer.

Purple Biotech is positioning CAPTN-3 as a direct answer to these problems. Its conditional activation mechanism is explicitly designed to improve the safety profile, potentially allowing for higher dosing and outpatient administration. Simultaneously, the dual-TAA targeting strategy may provide the enhanced specificity and potency needed to effectively combat solid tumors and overcome their defense mechanisms.

The Clinical Path Forward

While a robust patent portfolio is essential, the ultimate validation of the CAPTN-3 platform will come from clinical data. The company is now focused on advancing its pipeline, led by its first CAPTN-3 candidate, IM1240, which is moving toward clinical trials. This first-in-human study will be a critical test of the platform's core principles—whether the promise of enhanced safety and efficacy seen in preclinical models translates to patients.

A second candidate, IM1305, is following in preclinical development, demonstrating the platform’s intended function as a pipeline generator. The company’s portfolio also includes other clinical-stage assets, such as CM24 for pancreatic cancer, whose future development is contingent on partnerships—further highlighting the strategic importance of making the CAPTN-3 platform as attractive as possible to external collaborators.

With this key U.S. patent allowance secured, Purple Biotech has solidified the foundation upon which its future is being built. The focus now shifts from the legal intricacies of patent law to the scientific rigor of clinical trials, where the true potential of the CAPTN-3 platform to redefine cancer immunotherapy will be revealed.