OS Therapies, Inc. is a clinical-stage biotechnology company developing advanced treatments for rare and difficult-to-treat cancers. By leveraging the body’s immune system through immunotherapy and employing precision medicine principles, OS Therapies aims to create therapies that are both highly effective and less toxic. Their approach combines cutting-edge scientific platforms with targeted delivery methods to improve patient outcomes, particularly for those with limited treatment options. This dual strategy activates and directs the immune system to identify and destroy cancer cells while minimizing damage to healthy tissue.

The company’s lead program, OST-HER2, reflects its focus on tackling high unmet medical needs. This innovative immunotherapeutic vaccine is designed to treat osteosarcoma, a rare and aggressive bone cancer, and has potential applications for HER2-positive breast cancer. OST-HER2 uses a bioengineered version of the bacteria Listeria monocytogenes to trigger a strong immune response, targeting HER2-positive cancer cells with precision. As an “ultra-orphan” program, OST-HER2 addresses conditions that affect small, underserved patient populations with limited treatment options.

In addition to OST-HER2, OS Therapies is advancing its tunable Antibody-Drug Conjugate (tADC) platform, a next-generation technology that represents a breakthrough in precision cancer treatment. The tADC platform features a patented silicone linker that allows for the targeted delivery of cancer-killing drugs directly to tumors. By releasing the drugs only in the acidic environment of cancer cells, the tADC platform improves safety and minimizes side effects associated with traditional chemotherapy. This modular technology is designed to be adaptable, supporting a wide range of therapeutic applications for cancers beyond osteosarcoma.

Source: Company Documents

What sets OS Therapies apart is its emphasis on innovative approaches to both human and veterinary oncology. With its flagship OST-HER2 program receiving recognition through regulatory designations like Rare Pediatric Disease and Orphan Drug status, the company is well-positioned to bring transformative therapies to market. Moreover, using a modular and adaptable platform, such as the tunable ADC, gives OS Therapies a technological edge by enabling customizable treatments for a wide array of cancers. This dual focus on immunotherapy and precision drug delivery underscores their mission to redefine cancer care for underserved patient populations.

OS Therapies is targeting large, unmet needs in oncology with its therapeutic pipeline, focusing on osteosarcoma and HER2-positive solid tumors. Osteosarcoma, a type of bone cancer, has a total addressable market (TAM) of $1.7 billion for human applications (adults and pediatrics) and $150 million for canines. HER2-positive solid tumors, which include breast, bladder, and esophageal cancers, represent a $55 billion market. Additionally, the company’s tunable ADC (tADC) platform is positioned to address the broader global cancer treatment market, encompassing both chemotherapy and immunotherapies.

Osteosarcoma, a rare and aggressive bone cancer, primarily affects adolescents and young adults, with most cases diagnosed between the ages of 15 and 20. Classified as a solid tumor (a cancer that forms a mass or lump), osteosarcoma has seen no new treatments in over 40 years. Recurrence occurs in approximately 50% of patients, and once the cancer returns, it spreads rapidly to organs such as the lungs and brain. The prognosis for recurrent osteosarcoma is grim, with an 80-90% mortality rate and a life expectancy of just 12 months following recurrence. The current standard of care for primary osteosarcoma typically involves surgery, such as amputation, combined with nine months of aggressive chemotherapy that carries a 10% treatment-related mortality rate. Unfortunately, there are no approved treatments for secondary or recurrent osteosarcoma, highlighting a significant unmet need.

Source: Company Documents

The company’s lead program, OST-HER2, is designed to address these challenges by preventing osteosarcoma recurrence and improving overall survival rates. This innovative immunotherapy uses a bioengineered Listeria monocytogenes bacterium to activate the immune system against HER2-positive cancer cells. HER2 (human epidermal growth factor receptor 2) is a protein found on the surface of some cancer cells, promoting their growth. OST-HER2 has demonstrated promise not only in treating osteosarcoma but also in a range of HER2-positive solid tumors, including breast, bladder, and esophageal cancers. By enhancing immune system activity, OST-HER2 aims to disrupt tumor progression and reduce the likelihood of recurrence.

Beyond osteosarcoma, OS Therapies is exploring OST-HER2’s potential in treating HER2-positive solid tumors more broadly. In these cancers, OST-HER2 could complement existing therapies like trastuzumab, a common antibody treatment for HER2-positive cancers, by potentially preventing resistance to these drugs. For example, in gastroesophageal cancers, OST-HER2 may extend the efficacy of trastuzumab after initial treatments fail. Similarly, OST-HER2 can potentially improve the response to colorectal cancer treatments by increasing immune cell activity in HER2-positive subtypes. These applications underscore OST-HER2’s versatility and ability to address a wide spectrum of HER2-driven malignancies.

Source: Company Documents

OS Therapies’ broader pipeline also includes the tunable ADC (tADC) platform, representing a next-generation approach to precision cancer treatment. Unlike traditional chemotherapy, which affects both healthy and cancerous cells, tADC technology delivers cancer-killing drugs directly to tumors using a patented silicone linker. This targeted delivery minimizes side effects and increases the therapeutic effect. Combined with OST-HER2’s potential for immunotherapy, OS Therapies’ pipeline offers an integrated approach to tackling some of the most challenging cancers across human and veterinary medicine.

OST-HER2's mechanism of action is designed to harness the body's immune system to target and destroy HER2-positive cancer cells, including micro-metastases (small, undetectable clusters of cancer cells that spread beyond the primary tumor). At the heart of this process is the use of antigen-presenting cells (APCs), specialized immune cells that identify and process harmful invaders. When OST-HER2 is administered intravenously, the immune system rapidly clears the bioengineered Listeria monocytogenes vector, allowing APCs to process and present HER2 antigens—markers found on cancer cells—to the immune system.

Once activated, these APCs generate powerful HER2-specific T-cells within the patient's body. T-cells, a critical component of the immune system, multiply and travel through the bloodstream to hunt and attack HER2-positive cancer cells, including micro-metastases. As the T-cells destroy the cancer cells, their contents spill out, revealing additional cancer-associated targets that amplify the immune response. This action creates a cycle of ongoing T-cell activation, progressively extending the therapy's ability to control or eliminate cancer cells.

Source: Company Documents

This dynamic immune response makes OST-HER2 uniquely effective in addressing both visible tumors and hidden metastases. By leveraging the immune system's natural ability to adapt and expand its targets, OST-HER2 aims to prevent recurrence and improve survival outcomes for patients with HER2-positive cancers. The OS Therapies' approach underscores the company's commitment to precision immunotherapy and to addressing the full spectrum of cancer progression.

OST-HER2, OS Therapies’ lead immunotherapy candidate, is designed to treat HER2-positive cancers by activating the immune system to identify and destroy HER2-expressing tumor cells. While its primary focus is osteosarcoma, OST-HER2 shows strong potential for broader applications in HER2-positive tumors, including breast, bladder, and esophageal cancers. HER2 (human epidermal growth factor receptor 2) is a protein that promotes the growth of cancer cells and is overexpressed in several tumor types, making it a significant target for treatment.

The therapy’s versatility is enhanced by its ability to complement existing treatments like trastuzumab, a widely used antibody therapy for HER2-positive cancers. By preventing resistance to trastuzumab, OST-HER2 may extend the effectiveness of this standard treatment in cancers such as gastroesophageal and bladder tumors. Additionally, OST-HER2 could play a role in improving outcomes for HER2-positive colorectal cancer, a subset of patients who often show limited response to immunotherapy. These expanded indications position OST-HER2 as a promising solution for a range of HER2-driven cancers.

The therapy’s clinical development is supported by its success in preclinical and veterinary studies and promising interim data from the ongoing Phase 2b trial in humans. Results to date include improved event-free survival (EFS) rates at one year (32.5% versus 20.5% for the comparator group) and an overall survival (OS) rate of 90.4% at 18 months. Notably, OST-HER2 has shown no severe treatment-related adverse effects (Grades 3, 4, or 5), highlighting its favorable safety profile. Regulatory designations such as Fast Track, Orphan Drug, and Rare Pediatric Disease further reinforce its potential for addressing high unmet medical needs.

Source: Company Documents

With data from the Phase 2b trial expected in late 2024, OS Therapies plans to pursue accelerated FDA approval if final results are positive. Approval could result in a Priority Review Voucher (PRV), an incentive that may hold significant financial value. These clinical and regulatory milestones reflect the company’s strategic approach to expanding OST-HER2’s impact across multiple cancers.

OST-HER2 – Expanding Applications to HER2-Positive Breast Cancer

OS Therapies is preparing to expand OST-HER2’s applications beyond osteosarcoma with a Phase 1 trial for HER2-positive breast cancer, anticipated in 2025. In preclinical studies, OST31-164, the foundational technology behind OST-HER2, caused significant tumor regression in mouse models of HER2-expressing metastatic breast cancer. This response was directly associated with the therapy’s ability to activate HER2-specific immune cells (CD8 T-cells).

Anecdotal human data also shows promise, with one late-stage breast cancer patient leaving hospice care following treatment with OST31-164. The Phase 1 trial will evaluate the therapy’s safety and explore potential efficacy signals in patients with advanced or metastatic HER2-positive tumors.

Source: Company Documents

OS Therapies is advancing a robust pipeline of immunotherapies and precision cancer treatments targeting rare and difficult-to-treat cancers. At the center of the company’s therapeutic strategy is OST-HER2, an immunotherapeutic cancer vaccine developed for both human and canine osteosarcoma and HER2-positive solid tumors. The company is also advancing its tunable ADC (tADC) platform, which has potential applications in various cancers, including ovarian and breast cancer. This diverse pipeline underscores OS Therapies’ commitment to addressing significant unmet needs across oncology.

The company’s flagship program, OST-HER2, is undergoing a Phase 2b clinical trial for osteosarcoma in adult and pediatric patients. This trial is fully enrolled, with final data expected in the fourth quarter of 2024. In addition, OS Therapies is conducting a pivotal study of OST-HER2 in canine osteosarcoma, with results also anticipated in Q4 2024. Positive outcomes from these studies could support regulatory approvals for both human and veterinary applications, marking a significant step forward for patients and their caregivers.

OS Therapies’ tunable ADC platform is also progressing rapidly, with proof-of-concept data expected in 2025. This next-generation precision medicine platform focuses on delivering cancer-killing drugs directly to tumor cells while minimizing side effects. The platform’s flexibility allows for customization across multiple cancer types, with ongoing development targeting ovarian cancer, breast cancer, and other solid tumors. The OST-HER2 program and the tADC platform represent complementary approaches to tackling some of the most challenging cancers.

Source: Company Documents

The company’s near-term milestones reflect its catalyst-rich pipeline. Key upcoming data readouts include the final results from the Phase 2b trial for human osteosarcoma and the pivotal canine osteosarcoma study, both expected in late 2024. Additionally, OS Therapies plans to initiate a Phase 3 trial for OST-HER2 in breast cancer and advance its tADC program in 2025, adding to established proof-of-concept data for the platform. These milestones highlight the company’s strategic focus on clinical progress and regulatory success.

With a strong focus on precision medicine and a favorable regulatory pathway, OS Therapies is positioned to bring transformative treatments to market. The company has already received Orphan Drug, Fast Track, and Rare Pediatric Disease designations for OST-HER2, reflecting its potential to address high unmet medical needs. These regulatory advantages, near-term data readouts, and ongoing pipeline expansion make OS Therapies an emerging leader in oncology innovation.

OS Therapies’ regulatory strategy underscores its focus on addressing significant unmet medical needs in oncology. The company’s lead program, OST-HER2, has received Orphan Drug, Fast Track, and Rare Pediatric Disease designations from the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA). These designations are granted to therapies targeting rare diseases with few or no existing treatment options and provide regulatory benefits such as expedited review and eligibility for additional incentives.

If OST-HER2 achieves FDA approval, OS Therapies will qualify for a Priority Review Voucher (PRV), a highly sought-after regulatory incentive with an estimated market value of approximately $80-120M and perhaps as high as ~$160M. PRVs are transferable and can significantly accelerate the review timeline for another drug, providing substantial financial and strategic value to the company.

Osteosarcoma, the primary indication for OST-HER2, has seen no new FDA-approved treatments in over 40 years. This longstanding gap in innovation, combined with the therapy’s regulatory designations, positions OST-HER2 as a promising candidate for addressing critical unmet needs in human and veterinary oncology.

Source: Company Documents

OS Therapies’ pipeline is built on a foundation of robust intellectual property, with 21 issued patents across multiple countries and ten additional patents pending in key markets, including China, India, and South Korea. The company’s patented technologies span its OST-HER2 immunotherapy and its tunable Antibody-Drug Conjugate (tADC) platform, protecting core innovations that drive the effectiveness and uniqueness of its therapies.

For OST-HER2, patents focus on compositions and methods designed to prevent “escape mutations”—genetic changes in cancer cells that allow them to evade treatment. These include protections for using bioengineered Listeria monocytogenes bacteria in targeting HER2-positive tumors and methods combining immunotherapy and radiotherapy to enhance treatment outcomes. OST-HER2’s intellectual property portfolio includes issued patents in the U.S., Japan, and numerous European countries, providing coverage well into the 2030s. Notably, these patents support the therapy’s application across a range of HER2-driven cancers, from osteosarcoma to mammary tumors.

Source: Company Documents

The OST-tADC platform is equally well-protected, with patents covering its SiLinkers and Payload Cassettes—two essential components of its next-generation cancer drug delivery system. SiLinkers are specialized chemical linkers that attach cancer-killing drug payloads to targeting antibodies, ensuring the drugs are only released when they reach the tumor’s acidic environment. This precision reduces side effects and improves safety compared to traditional chemotherapy. Payload Cassettes refer to predesigned “building blocks” of cancer-killing agents that can be easily adapted for different types of cancer, offering flexibility in the platform’s application. Patents protecting these components extend the platform’s exclusivity into the mid-2030s, giving OS Therapies a strong competitive advantage.

Source: Company Documents

With such comprehensive intellectual property, OS Therapies is well-positioned to sustain long-term innovation and a competitive edge in the oncology space.

OS Therapies’ tunable Antibody-Drug Conjugate (tADC) platform is a next-generation technology designed to improve cancer treatment by delivering drugs directly to tumors. At the heart of this platform are patented silicon linkers (SiLinkers), which are advanced chemical connectors that attach cancer-killing drugs (payloads) to antibodies. These antibodies act as targeting agents, delivering the drugs to cancer cells while sparing healthy tissue. Unlike traditional linkers, which often cause side effects due to early drug release, SiLinkers are designed to release the payload only in the acidic environment of tumors, ensuring greater precision and safety.

The patented SiLinkers address several limitations of traditional linker technologies. For instance, they improve stability in circulation, meaning the drugs remain securely attached to their antibodies while traveling through the bloodstream. This strategy minimizes premature drug release, which can lead to harmful side effects like myelosuppression (a reduction in bone marrow activity that can weaken the immune system). Additionally, SiLinkers support multiple payloads per linker, allowing for the delivery of more than one cancer-killing agent at a time. This versatility makes the tADC platform highly adaptable, offering the potential to treat a wide range of cancers more effectively.

Another advantage of SiLinkers is their ability to unlock new intellectual property (IP) for existing drug payloads. Traditional linkers do not provide opportunities for new IP, but the unique properties of SiLinkers allow OS Therapies to patent combinations of older drugs with this advanced linker technology. By doing so, the company has enhanced the value of the tADC platform and extended its commercial potential. Moreover, SiLinkers avoid premature cleavage by enzymes like cathepsin, which are common in traditional systems, ensuring that the payloads reach their intended target with minimal degradation along the way.

Source: Company Documents

Overall, the tADC platform represents a significant leap forward in cancer treatment. By combining improved precision, stability, and versatility, OS Therapies’ patented linker technology positions the company to address a broad range of oncology needs while minimizing the side effects associated with traditional chemotherapy. This innovative approach to drug delivery underscores the company’s commitment to advancing precision medicine.

OS Therapies is advancing its therapeutic programs through strategic collaborations that support commercialization, advocacy, and research. A key partnership with Johnson & Johnson (J&J) provides access to cutting-edge laboratory resources and fosters collaboration within a global innovation network. This partnership enhances OS Therapies’ ability to accelerate the development of OST-HER2 and its tunable ADC platform, aligning the company with one of the healthcare industry’s leaders.

The company also works closely with osteosarcoma advocacy groups and patient organizations to build awareness and advance treatments for this rare and aggressive cancer. Contributors such as Miriam Cohen, Chair of the Osteosarcoma Collaborative, and Tony Trent, founder of the Tyler Trent Foundation, bring patient-focused insights to the company’s mission. Their involvement ensures that advocacy and community impact remain integral to OS Therapies’ approach.

Source: Company Documents

Importantly, in March 2023, OS Therapies’ work was featured on a 60 Minutes segment, highlighting a patient participating in an OST-HER2 trial. This national coverage underscores the potential impact of the company’s lead program and brings much-needed attention to osteosarcoma research and treatment innovation.

A seasoned team of biopharma experts leads OS Therapies with over 100 years of combined experience in oncology, immunology, and precision medicine. The leadership team brings a strong track record of developing and commercializing innovative therapies, launching more than 20 products, and securing over ten licensing deals. Their collective efforts have contributed to the success of some of the most recognizable therapies in the industry, including Revlimid, Herceptin, and Yervoy, which have generated billions in revenue.

Paul Romness, MHP, President and CEO, has more than 25 years of experience in the biopharma industry, including leadership roles at Johnson & Johnson, Amgen, and Boehringer Ingelheim. He has successfully launched nine major products in oncology, HIV, and chronic diseases. Paul holds a Master’s degree in Health Policy from George Washington University and a Bachelor’s in Finance from American University.

Robert Petit, PhD, Chief Medical and Scientific Officer, is the inventor and founding scientist of OS Therapies’ clinical-stage listeria cancer vaccine platform. With extensive experience at Bristol-Myers Squibb, MGI Pharma, and other biotech companies, Robert has a distinguished career in oncology and virology research. He earned his MD from Ohio State University and a BS in Life Science from Indiana State University.

Gerald Commissiong, Chief Business Officer, specializes in M&A, capital raising, and strategic planning, focusing on oncology, neurology, and regenerative medicine. Gerald has led initiatives at Amarantus Bioscience Holdings, Avant Diagnostics, and Todos Medical. He earned a BS in Management Science and Engineering from Stanford University.

Jutta Wanner, PhD, an advisor and founding scientist of the OST-tADC platform, has expertise in targeted drug conjugates, including tADC, tSMDC, and tmRNADC technologies. Jutta previously worked at Roche and co-founded BlinkBio. She holds a PhD from the University of Kansas and completed postdoctoral training at The Scripps Research Institute.

This leadership team’s deep pharmaceutical expertise and history of success position OS Therapies to effectively advance its innovative immunotherapy and precision medicine platforms. Their combined experience and proven track record provide confidence in the company’s ability to execute on its vision of redefining cancer care.

Source: Company Documents

OS Therapies offers a compelling investment opportunity through its focus on precision medicine, innovative technologies, and large, underserved markets.

Highlights include:

• Catalyst-Rich Pipeline: Multiple near-term data readouts, including Phase 2b trial results for OST-HER2 in human osteosarcoma and pivotal data for canine osteosarcoma, are expected in Q4 2024.

• Large Total Addressable Markets (TAM): The company is targeting significant oncology markets, including human HER2-positive solid tumors ($55 billion TAM), human osteosarcoma ($1.7 billion TAM), and canine osteosarcoma ($150 million TAM).

• Regulatory Advantages: OST-HER2 has received Orphan Drug, Fast Track, and Rare Pediatric Disease designations from the FDA and EMA. A Priority Review Voucher, valued at $80–120M (potentially as high as ~$160M), could further enhance the therapy’s financial impact upon approval.

• Innovative Technology Platforms: The tADC platform offers extensive flexibility through modular, “plug-and-play” designs for customizable drug delivery, with applications in ovarian, breast, and other solid tumors.

• Established Investment: Over $250 million has been invested in the Listeria platform to date, demonstrating significant prior validation and development.

These factors position OS Therapies as a significant player in precision oncology, with a near-term path to value creation through clinical and regulatory progress.