Bria-PROS+™: Immunotherapy for Prostate Cancer

About Bria-PROS+™

Prostate cancer presents unique biological and immunological challenges, and we’re developing Bria-PROS+™ to help address them through a personalized, off-the-shelf cellular immunotherapy approach. Bria-PROS+™ is an investigational candidate currently undergoing preclinical evaluation, designed to enhance targeted immune activity against prostate cancer cells.

The therapy originates from the scientific foundation of our Bria-OTS and Bria-OTS+™ platforms, which emphasize standardized, semi-allogeneic cell-based treatments that are tailored to the individual patient and yet designed to be accessible without the delays associated with patient-specific manufacturing. In creating Bria-PROS+™, we’re applying this modular platform to prostate cancer, aiming to support stronger antigen presentation and more coordinated T cell responses.

Prostate tumors often exhibit variable antigen expression and can create a suppressive microenvironment. We’re developing Bria-PROS+™ to overcome these barriers. It uses immune engagement strategies informed by our experience with Bria-IMT™ and next-generation OTS+™ constructs.

Latest Developments

Bria-PROS+ cell lines are being manufactured under Good Manufacturing Practice (GMP) conditions and projected to enter clinical testing in 1Q2026.

The latest data using the Bria-PROS+ cells were recently presented at the Society for Immunotherapy of Cancer Meeting in November.  The data showed that:
Bria-PROS+ (part of the Bria-OTS⁺ platform technology) demonstrates a multifaceted mechanism of action characterized by:
  • Broad antigenic coverage, expressing diverse Tumor-Associated Antigens (TAAs), Tumor specific Antigens (TSA) and Unconventional Cancer Antigens (UCAs). Smith C.C., Selitsky S.R., Chai S., Armistead P.M., Vincent B.G., Serody J.S. Alternative tumour-specific antigens. Nature Reviews Cancer. 2019;19(8): 509-525
  • Comprehensive immune engagement, activating both adaptive and innate immune compartments.
  • Enhanced tumor recognition and control, counteracting immune escape via Natural Killer (NK) cell activation, even in HLA-deficient contexts.
  • Durable immune memory formation, supporting long-lasting anti-tumor protection upon boosting.
  • Flexible applicability, suitable for both personalized and off-the-shelf vaccine formats with strong stability profiles.
  • Streamlined clinical use, featuring a simplified administration process.
  • Favorable safety expectations, with an anticipated low toxicity and good tolerability profile

Additional data and development updates can be reviewed in the latest SITC poster: 2025-SITC-Poster

What Makes Bria-PROS+™ Different and Why It Matters

Bria-PROS+™ is being engineered to incorporate several characteristics that distinguish it from existing investigational approaches:

  • Personalized with Standardized, off-the-shelf design intended to enable consistent product availability and avoid the logistical constraints of autologous therapies.
  • Enhanced immune-interface features, including components designed to stimulate T cell interaction with prostate cancer–associated antigens.
  • Potential combinability with checkpoint inhibitor strategies, subject to continued preclinical analysis and regulatory guidance.
  • Integration within the Bria-OTS+™ system, allowing for future exploration of HLA-based matching strategies that may help optimize immune activation.
  • Next-generation modifications informed by prior iterations to support more robust and targeted responses.

These design elements reflect our objective to create an investigational therapy that aligns with scientific needs in prostate cancer while supporting the broader goals of immunotherapy accessibility and consistency.

Who Might Benefit

The Bria-PROS+™ program is focused on prostate cancer populations with significant unmet needs. Potential future candidates may include individuals with:

  • Metastatic or advanced disease
  • Treatment-resistant or castrate-resistant prostate cancer
  • Disease progression following standard-of-care therapies
  • Biomarker or HLA characteristics that may support immunotherapy strategies

As development continues, we’ll evaluate Bria-PROS+™ across scenarios where additional immunotherapeutic approaches may be warranted. Preclinical analyses and biomarker assessments will guide the refinement of targeted patient populations.

Future Outlook & Key Milestones

Bria-PROS+™ is scheduled to enter the clinic in the first quarter of 2026.

Bria-PROS+™ and Our Mission

Our mission is to advance scientifically rigorous, off-the-shelf immunotherapy solutions for cancers with limited long-term treatment options. Bria-PROS+™ represents an expansion of this mission into prostate cancer, applying our platform-based approach to a disease area that needs new strategies. Through the continued development of Bria-PROS+™ within our Bria-OTS+™ ecosystem, we aim to help broaden the future landscape of accessible, precisely designed immunotherapies.