#USA #Cambridge #Harbour BioMed #Porustobart #Solstice Oncology

Solstice Oncology Secures Major Funding for Porustobart

In a significant advance for cancer treatment, Solstice Oncology has completed a successful $225 million Series A financing. The financing, led by RA Capital Management with contributions from Canaan Partners, Forbion, and other investors, will be pivotal in developing Porustobart, a second-generation Fc-enhanced CTLA-4 antibody. Solstice aims to enhance cancer treatment by addressing it at earlier stages, specifically the neoadjuvant setting, where there is an opportunity to significantly improve patient outcomes.

Focus on Neoadjuvant Therapy

The company’s leading candidate, Porustobart, is being evaluated for its effectiveness in treating microsatellite-stable (MSS) stage II-III colon cancer. This indication remains largely underserved by current immunotherapies, and Solstice's Phase 2 trial is set to open for patient enrollment in early Q4 2026.

Porustobart represents a strategic evolution in immunotherapy, specifically designed to augment the immune system's ability to combat cancer at the neoadjuvant stage of treatment. This innovative approach aims to harness the potential of the immune system while the tumor is still present and the immune response is robust, preventing the disease from hardening into resistance against therapies.

Clinical Development and Previous Trial Success

Prior to this financing announcement, a Phase 2 clinical study conducted by Harbour BioMed demonstrated promising results for Porustobart in combination with tislelizumab (a PD-1 inhibitor) among late-line MSS metastatic colorectal cancer patients, achieving an objective response rate of 30%. With 7 out of 23 patients showing positive responses, the data entails a median duration of response lasting 8.4 months. These findings indicate a favorable safety profile, which encourages further clinical investigations in conjunction with PD-(L)1 blockade therapies.

Dr. Jingsong Wang, the Founder and CEO of Harbour BioMed, expressed excitement about the financing and the launch of Solstice, emphasizing their commitment to advancing Porustobart and exploring its global potential. “It is crucial to support the ongoing development of this differentiated CTLA-4 antibody to benefit patients worldwide,” he stated.

The Vision of Solstice Oncology

Caroline Loew, PhD, the CEO of Solstice Oncology, highlighted the company's vision to change the oncology landscape by focusing on early treatment interventions. “We believe that treating disease earlier in the neoadjuvant setting can allow the immune response to act systemically, targeting micrometastatic disease beyond the primary tumor, which is where we see the most significant opportunity to enhance cure rates and long-term survival,” she remarked.

Since its inception in February 2026, the Solstice team has demonstrated agility and focus. In addition to securing funding, they have successfully filed and cleared an Investigational New Drug (IND) application and are now primed to move into what is anticipated to be a ground-breaking Phase 2 trial, with results expected by the end of 2027.

The Future of Immunotherapy with Harbour BioMed

Harbour BioMed's dedication to novel antibody therapeutic discovery underscores its commitment to revolutionizing treatment protocols for conditions including immunological and oncological diseases. Through innovative technology platforms like Harbour Mice®, they contribute to the development of fully human monoclonal antibodies, further enhancing the prospects for impactful therapies.

As Solstice Oncology embarks on this critical journey supported by significant investment, the landscape of cancer treatment stands on the brink of transformative change. The culmination of discovery, robust clinical testing, and strategic investments signifies a hopeful future for countless patients facing cancer.

For additional information about Solstice Oncology and the development of Porustobart, visit www.solsticeoncology.com and for Harbour BioMed information, please visit www.harbourbiomed.com.