CytoSite Bio announced a strategic collaboration agreement with Lantheus Holdings, Inc. for the clinical development and potential commercialization of an investigational granzyme B-targeted Positron Emission Tomography (PET) imaging radiotracer. The Phase 1-ready imaging technology represents a potential breakthrough in real-time immunotherapy monitoring, offering physicians the ability to assess treatment efficacy within days rather than months.
Novel Biomarker Technology for Immune Response Assessment
The investigational PET imaging radiotracer targets granzyme B, an enzyme released upon activation of immune cells to destroy harmful cells, including cancer. Early studies of the imaging tracer have demonstrated potential to evaluate whether immunotherapies are effectively activating the immune system, addressing a critical gap in current cancer treatment monitoring.
The technology could enable physicians to measure the early efficacy of immunotherapies within days of first dose and modify treatment accordingly, rather than waiting for months to fully understand if the treatment is working. This rapid assessment capability represents a significant advancement over current monitoring methods that rely on delayed imaging or clinical response indicators.
Collaboration Structure and Commercial Potential
Under the collaboration agreement, CytoSite will lead initial clinical development while Lantheus holds an exclusive option to acquire worldwide development and commercialization rights to the radiotracer. The partnership structure allows CytoSite to advance the technology through early clinical phases while providing a clear commercialization pathway through Lantheus' established radiopharmaceutical expertise.
CytoSite is eligible to receive payments for development, regulatory and commercial milestones, plus royalties on future product sales. The agreement provides Lantheus with an exclusive option to license worldwide rights to CytoSite's novel imaging technology.
Clinical Applications and Drug Development Impact
Beyond patient care applications, pharmaceutical developers can use the investigational imaging tracer to gain an early read-out of efficacy for new therapies, enabling faster decision-making and more efficient allocation of resources. This capability could accelerate drug development timelines by providing rapid biomarker feedback during clinical trials.
"The clinical data we have generated to date validates our belief that use of PET imaging to detect active Granzyme B has the potential to transform outcomes in immuno-oncology, autoimmune-mediated and inflammatory diseases," said Benjamin Larimer, PhD, Co-founder and CEO of CytoSite. "We are excited to be partnering with Lantheus to bring Granzyme B PET imaging to the forefront."
Broader Therapeutic Applications
The granzyme B biomarker technology extends beyond oncology applications. According to the companies, the imaging approach has potential applications in autoimmune-mediated and inflammatory diseases, where immune system activation plays a central role in disease progression and treatment response.
"If approved, CytoSite's proprietary Granzyme B biomarker could provide a valuable tool for oncologists, radiologists and medical professionals to enable improved outcomes for cancer patients and rapidly expand options for new immunotherapies," said Umar Mahmood, MD, PhD, Co-founder of CytoSite, Chief of Nuclear Medicine and Molecular Imaging in the Department of Radiology at Massachusetts General Hospital and Professor of Radiology at Harvard Medical School.
The collaboration creates a pathway for CytoSite to advance this promising technology in parallel with the company's own radiotherapeutic program, which focuses on developing novel radiopharmaceuticals that enable the quantification and modulation of immune activation to improve cancer immunotherapy.
